Gene Summary

Gene:RBP1; retinol binding protein 1
Summary:This gene encodes the carrier protein involved in the transport of retinol (vitamin A alcohol) from the liver storage site to peripheral tissue. Vitamin A is a fat-soluble vitamin necessary for growth, reproduction, differentiation of epithelial tissues, and vision. Multiple transcript variants encoding different isoforms have been found for this gene. [provided by RefSeq, Aug 2008]
Databases:OMIM, HGNC, Ensembl, GeneCard, Gene
Protein:retinol-binding protein 1
Source:NCBIAccessed: 01 September, 2019


What does this gene/protein do?
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Cancer Overview

Research Indicators

Publications Per Year (1994-2019)
Graph generated 02 September 2019 using data from PubMed using criteria.

Literature Analysis

Mouse over the terms for more detail; many indicate links which you can click for dedicated pages about the topic.

  • Tumor Suppressor Gene
  • Chromosome 3
  • Oligonucleotide Array Sequence Analysis
  • Breast Cancer
  • Membrane Proteins
  • Brain Tumours
  • Cervical Cancer
  • Neoplasm Proteins
  • Messenger RNA
  • Retinoids
  • Retinol-Binding Proteins, Plasma
  • Neoplastic Cell Transformation
  • Epigenetics
  • Tissue Array Analysis
  • HeLa Cells
  • Signal Transduction
  • Biomarkers, Tumor
  • Transfection
  • DNA-Binding Proteins
  • CpG Islands
  • Retinol-Binding Proteins
  • RBP1
  • Receptors, Retinoic Acid
  • SOXC Transcription Factors
  • Polymerase Chain Reaction
  • Epithelial Cells
  • DNA Methylation
  • Gene Expression
  • Cancer Gene Expression Regulation
  • DNA Mutational Analysis
  • Immunohistochemistry
  • Adenocarcinoma
  • Retinoic Acid
  • Gene Expression Profiling
  • Gene Silencing
  • Promoter Regions
  • Uterine Cancer
  • Brain Tumours
  • Retinol-Binding Proteins, Cellular
  • Transcription
  • Squamous Cell Carcinoma
Tag cloud generated 01 September, 2019 using data from PubMed, MeSH and CancerIndex

Specific Cancers (4)

Data table showing topics related to specific cancers and associated disorders. Scope includes mutations and abnormal protein expression.

Note: list is not exhaustive. Number of papers are based on searches of PubMed (click on topic title for arbitrary criteria used).

Latest Publications: RBP1 (cancer-related)

Celestino R, Nome T, Pestana A, et al.
CRABP1, C1QL1 and LCN2 are biomarkers of differentiated thyroid carcinoma, and predict extrathyroidal extension.
BMC Cancer. 2018; 18(1):68 [PubMed] Free Access to Full Article Related Publications
BACKGROUND: The prognostic variability of thyroid carcinomas has led to the search for accurate biomarkers at the molecular level. Follicular thyroid carcinoma (FTC) is a typical example of differentiated thyroid carcinomas (DTC) in which challenges are faced in the differential diagnosis.
METHODS: We used high-throughput paired-end RNA sequencing technology to study four cases of FTC with different degree of capsular invasion: two minimally invasive (mFTC) and two widely invasive FTC (wFTC). We searched by genes differentially expressed between mFTC and wFTC, in an attempt to find biomarkers of thyroid cancer diagnosis and/or progression. Selected biomarkers were validated by real-time quantitative PCR in 137 frozen thyroid samples and in an independent dataset (TCGA), evaluating the diagnostic and the prognostic performance of the candidate biomarkers.
RESULTS: We identified 17 genes significantly differentially expressed between mFTC and wFTC. C1QL1, LCN2, CRABP1 and CILP were differentially expressed in DTC in comparison with normal thyroid tissues. LCN2 and CRABP1 were also differentially expressed in DTC when compared with follicular thyroid adenoma. Additionally, overexpression of LCN2 and C1QL1 were found to be independent predictors of extrathyroidal extension in DTC.
CONCLUSIONS: We conclude that the underexpression of CRABP1 and the overexpression of LCN2 may be useful diagnostic biomarkers in thyroid tumours with questionable malignity, and the overexpression of LCN2 and C1QL1 may be useful for prognostic purposes.

Koensgen D, Stope MB, Tuerbachova I, et al.
Expression, Intracellular Localization, and Prognostic Value of Plasminogen Activator Inhibitor 1 and PAI-1 RNA-Binding Protein 1 in Primary and Recurrent Ovarian Cancer: A Study of the Tumor Bank Ovarian Cancer Network.
Gynecol Obstet Invest. 2018; 83(5):508-514 [PubMed] Related Publications
BACKGROUND: The plasminogen activator system plays a key role in ovarian cancer (OC) tumor progression. The plasminogen activator inhibitor type 1 (PAI-1) and the recently identified PAI-1 RNA binding protein 1 (PAI-RBP1) are primary regulators of plasminogen activation and thus are putative biomarkers for OC progression.
METHODS: One hundred fifty six OC patients were analyzed to identify the presence of PAI-1 and PAI-RBP1 and subsequently correlated to clinicopathological parameters. Primary cells obtained from OC patient samples were applied in fluorescence microscopy analysis for examination of PAI-1 and PAI-RBP1 distribution.
RESULTS: PAI-1 and PAI-RBP1 have been found to be predictive markers for OC patients' outcome. PAI-1 levels significantly correlated with volume of ascites, FIGO staging, and lymph node status. PAI-RBP1 expression significantly correlated with age at first diagnosis, histological tumor type, presence of distant metastasis (pM), and recurrence. PAI-1 showed a trend toward association and PAI-RBP1 was significantly associated with progression-free survival. Notably, PAI-1 protein in recurrent OC tissues was exclusively localized in the nucleus.
CONCLUSION: This study has shown that a combination of PAI-1 and PAI-RBP1 may represent novel prognostic factor for OC. Prospective trials are needed.

Remacha L, Comino-Méndez I, Richter S, et al.
Targeted Exome Sequencing of Krebs Cycle Genes Reveals Candidate Cancer-Predisposing Mutations in Pheochromocytomas and Paragangliomas.
Clin Cancer Res. 2017; 23(20):6315-6324 [PubMed] Related Publications

Yokoi K, Yamashita K, Ishii S, et al.
Comprehensive molecular exploration identified promoter DNA methylation of the CRBP1 gene as a determinant of radiation sensitivity in rectal cancer.
Br J Cancer. 2017; 116(8):1046-1056 [PubMed] Free Access to Full Article Related Publications
BACKGROUND: Neoadjuvant chemoradiotherapy (NCRT) for advanced rectal cancer (RC) is a well-evidenced therapy; however, some RC patients have no therapeutic response. Patient selection for NCRT so that non-responsive patients are excluded has been subjective. To date, no molecular markers indicating radiation sensitivity have been reported.
METHODS: We irradiated six colorectal cancer (CRC) cell lines and identified HCT116 cells as radiation-sensitive and HCT15 and DLD-1 cells as radiation resistant. Using a microarray, we selected candidate radiation sensitivity marker genes by choosing genes whose expression was consistent with a radiation-resistant or sensitive cell phenotype.
RESULTS: Among candidate genes, cellular retinol binding protein 1 (CRBP1) was of particular interest because it was not only induced in HCT116 cells by tentative 10 Gy radiation treatments, but also its expression was increased in HCT116-derived radiation-resistant cells vs parental cells. Forced expression of CRBP1 decreased the viability of both HCT15 and DLD-1 cells in response to radiation therapy. We also confirmed that CRBP1 was epigenetically silenced by hypermethylation of its promoter DNA, and that the quantitative methylation value of CRBP1 significantly correlated with histological response in RC patients with NCRT (P=0.031).
CONCLUSIONS: Our study identified CRBP1 as a radiation-sensitive predictor in RC.

Iida T, Iwanami A, Sanosaka T, et al.
Whole-Genome DNA Methylation Analyses Revealed Epigenetic Instability in Tumorigenic Human iPS Cell-Derived Neural Stem/Progenitor Cells.
Stem Cells. 2017; 35(5):1316-1327 [PubMed] Related Publications
Although human induced pluripotent stem cell (hiPSC) derivatives are considered promising cellular resources for regenerative medicine, their tumorigenicity potentially limits their clinical application in hiPSC technologies. We previously demonstrated that oncogenic hiPSC-derived neural stem/progenitor cells (hiPSC-NS/PCs) produced tumor-like tissues that were distinct from teratomas. To gain insight into the mechanisms underlying the regulation of tumorigenicity in hiPSC-NS/PCs, we performed an integrated analysis using the Infinium HumanMethylation450 BeadChip array and the HumanHT-12 v4.0 Expression BeadChip array to compare the comprehensive DNA methylation and gene expression profiles of tumorigenic hiPSC-NS/PCs (253G1-NS/PCs) and non-tumorigenic cells (201B7-NS/PCs). Although the DNA methylation profiles of 253G1-hiPSCs and 201B7-hiPSCs were similar regardless of passage number, the methylation status of the global DNA methylation profiles of 253G1-NS/PCs and 201B7-NS/PCs differed; the genomic regions surrounding the transcriptional start site of the CAT and PSMD5 genes were hypermethylated in 253G1-NS/PCs but not in 201B7-NS/PCs. Interestingly, the aberrant DNA methylation profile was more pronounced in 253G1-NS/PCs that had been passaged more than 15 times. In addition, we identified aberrations in DNA methylation at the RBP1 gene locus; the DNA methylation frequency in RBP1 changed as 253G1-NS/PCs were sequentially passaged. These results indicate that different NS/PC clones have different DNA methylomes and that DNA methylation patterns are unstable as cells are passaged. Therefore, DNA methylation profiles should be included in the criteria used to evaluate the tumorigenicity of hiPSC-NS/PCs in the clinical setting. Stem Cells 2017;35:1316-1327.

Napoli JL
Cellular retinoid binding-proteins, CRBP, CRABP, FABP5: Effects on retinoid metabolism, function and related diseases.
Pharmacol Ther. 2017; 173:19-33 [PubMed] Free Access to Full Article Related Publications
Cellular binding-proteins (BP), including CRBP1, CRBP2, CRABP1, CRABP2, and FABP5, shepherd the poorly aqueous soluble retinoids during uptake, metabolism and function. Holo-BP promote efficient use of retinol, a scarce but essential nutrient throughout evolution, by sheltering it and its major metabolite all-trans-retinoic acid from adventitious interactions with the cellular milieu, and by imposing specificity of delivery to enzymes, nuclear receptors and other partners. Apo-BP reflect cellular retinoid status and modify activities of retinoid metabolon enzymes, or exert non-canonical actions. High ligand binding affinities and the nature of ligand sequestration necessitate external factors to prompt retinoid release from holo-BP. One or more of cross-linking, kinetics, and colocalization have identified these factors as RDH, RALDH, CYP26, LRAT, RAR and PPARβ/δ. Michaelis-Menten and other kinetic approaches verify that BP channel retinoids to select enzymes and receptors by protein-protein interactions. Function of the BP and enzymes that constitute the retinoid metabolon depends in part on retinoid exchanges unique to specific pairings. The complexity of these exchanges configure retinol metabolism to meet the diverse functions of all-trans-retinoic acid and its ability to foster contrary outcomes in different cell types, such as inducing apoptosis, differentiation or proliferation. Altered BP expression affects retinoid function, for example, by impairing pancreas development resulting in abnormal glucose and energy metabolism, promoting predisposition to breast cancer, and fostering more severe outcomes in prostate cancer, ovarian adenocarcinoma, and glioblastoma. Yet, the extent of BP interactions with retinoid metabolon enzymes and their impact on retinoid physiology remains incompletely understood.

Liu RZ, Li S, Garcia E, et al.
Association between cytoplasmic CRABP2, altered retinoic acid signaling, and poor prognosis in glioblastoma.
Glia. 2016; 64(6):963-76 [PubMed] Free Access to Full Article Related Publications
Retinoic acid (RA), a metabolite of vitamin A, is required for the regulation of growth and development. Aberrant expression of molecules involved in RA signaling has been reported in various cancer types including glioblastoma multiforme (GBM). Cellular retinoic acid-binding protein 2 (CRABP2) has previously been shown to play a key role in the transport of RA to retinoic acid receptors (RARs) to activate their transcription regulatory activity. Here, we demonstrate that CRABP2 is predominantly located in the cytoplasm of GBM tumors. Cytoplasmic, but not nuclear, CRABP2 levels in GBM tumors are associated with poor patient survival. Treatment of malignant glioma cell lines with RA results in a dose-dependent increase in accumulation of CRABP2 in the cytoplasm. CRABP2 knockdown reduces proliferation rates of malignant glioma cells, and enhances RA-induced RAR activation. Levels of CRYAB, a small heat shock protein with anti-apoptotic activity, and GFAP, an astrocyte-specific intermediate filament protein, are greatly reduced in CRABP2-depleted cells. Restoration of CRYAB expression partially but significantly reversed the effect of CRABP2 depletion on RAR activation. Our combined in vivo and in vitro data indicate that: (i) CRABP2 is an important determinant of clinical outcome in GBM patients, and (ii) the mechanism of action of CRABP2 in GBM involves sequestration of RA in the cytoplasm and activation of an anti-apoptotic pathway, thereby enhancing proliferation and preventing RA-mediated cell death and differentiation. We propose that reducing CRABP2 levels may enhance the therapeutic index of RA in GBM patients.

Yang YP, Wang S, Li X, Schor NF
Cell Line-Dependent Variability of Coordinate Expression of p75NTR and CRABP1 and Modulation of Effects of Fenretinide on Neuroblastoma Cells.
Oxid Med Cell Longev. 2016; 2016:7568287 [PubMed] Free Access to Full Article Related Publications
Neuroblastoma is a childhood neural crest tumor. Fenretinide, a retinoic acid analogue, induces accumulation of mitochondrial reactive oxygen species and consequent apoptosis in neuroblastoma cells. The p75 neurotrophin receptor (p75NTR) enhances the antineuroblastoma cell efficacy of fenretinide in vitro. We examined the role of the retinoid binding protein, CRABP1, in p75NTR-mediated potentiation of the efficacy of fenretinide. Knockdown and overexpression, respectively, of either p75NTR or CRABP1 were effected in neuroblastoma cell lines using standard techniques. Expression was determined by qRT-PCR and confirmed at the protein level by Western blot. Metabolic viability was determined by Alamar blue assay. While protein content of CRABP1 correlated roughly with that of p75NTR in the three neuroblastoid or epithelioid human neuroblastoma cell lines studied, manipulation of p75NTR expression resulted in cell line-dependent, variable change in CRABP1 expression. Furthermore, in some cell lines, induced expression of CRABP1 in the absence of p75NTR did not alter cell sensitivity to fenretinide treatment. The effects of manipulation of p75NTR expression on CRABP1 expression and the effects of CRABP1 expression on fenretinide efficacy are therefore neuroblastoma cell line-dependent. Potentiation of the antineuroblastoma cell effects of fenretinide by p75NTR is not mediated solely through CRABP1.

Liu RZ, Garcia E, Glubrecht DD, et al.
CRABP1 is associated with a poor prognosis in breast cancer: adding to the complexity of breast cancer cell response to retinoic acid.
Mol Cancer. 2015; 14:129 [PubMed] Free Access to Full Article Related Publications
BACKGROUND: Clinical trials designed to test the efficacy of retinoic acid (RA) as an adjuvant for the treatment of solid cancers have been disappointing, primarily due to RA resistance. Estrogen receptor (ER)-negative breast cancer cells are more resistant to RA than ER-positive cells. The expression and subcellular distribution of two RA-binding proteins, FABP5 and CRABP2, has already been shown to play critical roles in breast cancer cell response to RA. CRABP1, a third member of the RA-binding protein family, has not previously been investigated as a possible mediator of RA action in breast cancer.
METHODS: CRABP1 and CRABP2 expression in primary breast tumor tissues was analyzed using gene expression and tissue microarrays. CRABP1 levels were manipulated using siRNAs and by transient overexpression. RA-induced subcellular translocation of CRABPs was examined by immunofluorescence microscopy and immunoblotting. RA-induced transactivation of RAR was analyzed using a RA response element (RARE)-driven luciferase reporter system. Effects of CRABP1 expression and RA treatment on downstream gene expression were investigated by semi-quantitative RT-PCR analysis.
RESULTS: Compared to normal mammary tissues, CRABP1 expression is significantly down-regulated in ER+ breast tumors, but maintained in triple-negative breast cancers. Elevated CRABP1 levels are associated with poor patient prognosis, high Ki67 immunoreactivity and high tumor grade in breast cancer. The prognostic significance of CRABP1 is attributed to its cytoplasmic localization. We demonstrate that CRABP1 expression attenuates RA-induced cell growth arrest and inhibits RA signalling in breast cancer cells by sequestering RA in the cytoplasm. We also show that CRABP1 affects the expression of genes involved in RA biosynthesis, trafficking and metabolism.
CONCLUSIONS: CRABP1 is an adverse factor for clinical outcome in triple-negative breast cancer and a potent inhibitor of RA signalling in breast cancer cells. Our data indicate that CRABP1, in conjunction with previously identified CRABP2 and FABP5, plays a key role in breast cancer cell response to RA. We propose that these three RA-binding proteins can serve as biomarkers for predicting triple-negative breast cancer response to RA, with elevated levels of either cytoplasmic CRABP1 or FABP5 associated with RA resistance, and elevated levels of nuclear CRABP2 associated with sensitivity to RA.

Choi N, Park J, Lee JS, et al.
miR-93/miR-106b/miR-375-CIC-CRABP1: a novel regulatory axis in prostate cancer progression.
Oncotarget. 2015; 6(27):23533-47 [PubMed] Free Access to Full Article Related Publications
Capicua (CIC) has been implicated in pathogenesis of spinocerebellar ataxia type-1 (SCA1) neurodegenerative disease and some types of cancer; however, the role of CIC in prostate cancer remains unknown. Here we show that CIC suppresses prostate cancer progression. CIC expression was markedly decreased in human prostatic carcinoma. CIC overexpression suppressed prostate cancer cell proliferation, invasion, and migration, whereas CIC RNAi exerted opposite effects. We found that knock-down of CIC derepresses expression of ETV5 and CRABP1 in LNCaP and PC-3 cells, respectively, thereby promoting cell proliferation and invasion. We also discovered that miR-93, miR-106b, and miR-375, which are known to be frequently overexpressed in prostate cancer patients, cooperatively down-regulate CIC levels to promote cancer progression. Altogether, we suggest miR-93/miR-106b/miR-375-CIC-CRABP1 as a novel key regulatory axis in prostate cancer progression.

Doldo E, Costanza G, Agostinelli S, et al.
Vitamin A, cancer treatment and prevention: the new role of cellular retinol binding proteins.
Biomed Res Int. 2015; 2015:624627 [PubMed] Free Access to Full Article Related Publications
Retinol and vitamin A derivatives influence cell differentiation, proliferation, and apoptosis and play an important physiologic role in a wide range of biological processes. Retinol is obtained from foods of animal origin. Retinol derivatives are fundamental for vision, while retinoic acid is essential for skin and bone growth. Intracellular retinoid bioavailability is regulated by the presence of specific cytoplasmic retinol and retinoic acid binding proteins (CRBPs and CRABPs). CRBP-1, the most diffuse CRBP isoform, is a small 15 KDa cytosolic protein widely expressed and evolutionarily conserved in many tissues. CRBP-1 acts as chaperone and regulates the uptake, subsequent esterification, and bioavailability of retinol. CRBP-1 plays a major role in wound healing and arterial tissue remodelling processes. In the last years, the role of CRBP-1-related retinoid signalling during cancer progression became object of several studies. CRBP-1 downregulation associates with a more malignant phenotype in breast, ovarian, and nasopharyngeal cancers. Reexpression of CRBP-1 increased retinol sensitivity and reduced viability of ovarian cancer cells in vitro. Further studies are needed to explore new therapeutic strategies aimed at restoring CRBP-1-mediated intracellular retinol trafficking and the meaning of CRBP-1 expression in cancer patients' screening for a more personalized and efficacy retinoid therapy.

Guo M, Alumkal J, Drachova T, et al.
CHFR methylation strongly correlates with methylation of DNA damage repair and apoptotic pathway genes in non-small cell lung cancer.
Discov Med. 2015; 19(104):151-8 [PubMed] Related Publications
DNA methylation occurs commonly in non-small cell lung cancer (NSCLC). We sought to determine the frequency and relationship of methylation of key genes involved in the pathways of mitotic checkpoint control, DNA damage repair, apoptosis, and growth factor signaling in these patients. We analyzed the DNA methylation status of eight genes (CHFR, FANCF, MGMT, p16, DAPK, ASC or TMS-1, RAR-B, and CRBP1) using nested methylation-specific PCR (MSP) on over 314 paraffin-embedded, human non-small cell lung cancer samples. We determined the methylation frequency of each gene in addition to the association of the methylation of each gene with other members of the panel. Methylation was a common event in these samples. Our methylation analysis showed frequencies of methylation of 10% for CHFR, 14% for FANCF, 30% for MGMT, 29% for p16, 17% for DAPK, 33% for ASC, 38% for RAR-B, and 7% for CRBP1. There was a strong correlation between methylation of the mitotic G2-M checkpoint gene, CHFR, and methylation of other genes in our panel involved in DNA damage repair (FANCF and MGMT) and apoptosis (DAPK and ASC) but not with other genes in our panel, including p16 (the G1-S checkpoint gene), CRBP1, or RAR-B. In addition, MGMT methylation strongly correlated with the pro-apoptotic gene, ASC. There are distinct associations of methylated genes in non-small cell lung cancer involving DNA damage repair, apoptosis, and the G2-M mitotic checkpoint control. Further studies are warranted to determine whether these methylation patterns have implications for prognosis in addition to prediction of response to chemotherapeutic agents commonly used in the treatment of non-small cell lung cancer, such as radiotherapy and platinum- or taxane-based chemotherapy.

Walter RF, Mairinger FD, Werner R, et al.
SOX4, SOX11 and PAX6 mRNA expression was identified as a (prognostic) marker for the aggressiveness of neuroendocrine tumors of the lung by using next-generation expression analysis (NanoString).
Future Oncol. 2015; 11(7):1027-36 [PubMed] Related Publications
BACKGROUND: Neuroendocrine tumors of the lung (NELC) account for 25% of all lung cancer cases and transcription factors may drive dedifferentiation of these tumors. This study was conducted to identify supportive diagnostic and prognostic biomarkers.
MATERIALS & METHODS: A total of 16 TC, 13 AC, 16 large cell neuroendocrine carcinomas and 15 small cell lung cancer were investigated for the mRNA expression of 11 transcription factors and related genes (MYB, MYBBP1A, OCT4, PAX6, PCDHB, RBP1, SDCBP, SOX2, SOX4, SOX11, TEAD2).
RESULTS: SOX4 (p = 0.0002), SOX11 (p < 0.0001) and PAX6 (p = 0.0002) were significant for tumor type. Elevated PAX6 and SOX11 expression correlated with poor outcome in large cell neuroendocrine carcinomas and small cell lung cancer (p < 0.0001 and p = 0.0232, respectively) based on survival data of 34 patients (57%).
CONCLUSION: Aggressiveness of NELC correlated with increasing expression of transcription factors. SOX11 seems to be a highly valuable diagnostic and prognostic marker for aggressive NELC.

He D, Zhang YW, Zhang NN, et al.
Aberrant gene promoter methylation of p16, FHIT, CRBP1, WWOX, and DLC-1 in Epstein-Barr virus-associated gastric carcinomas.
Med Oncol. 2015; 32(4):92 [PubMed] Related Publications
Alterations in global DNA methylation and specific regulatory gene methylation are frequently found in cancer, but the significance of these epigenetic changes in EBV-associated gastric carcinoma (EBVaGC) remains unclear. We evaluated global DNA methylation status in 49 EBVaGC and 45 EBV-negative gastric carcinoma (EBVnGC) tissue samples and cell lines by 5-methylcytosine immunohistochemical staining and methylation quantification. We determined promoter methylation status and protein expression for the p16, FHIT, CRBP1, WWOX, and DLC-1 genes in tissues and studied the correlation between CpG island methylator phenotype (CIMP) class and clinicopathological characteristics. Changes in gene methylation and mRNA expression in EBVaGC cell line SNU-719 and in EBVnGC cell lines SGC-7901, BGC-823, and AGS were assessed after treatment with 5-aza-2'-deoxycytidine (5-aza-dC), trichostatin A (TSA), or a combination of both, by methylation-specific PCR and quantitative real-time RT-PCR. Global genomic DNA hypomethylation was more pronounced in EBVnGC than in EBVaGC. Promoter methylation of all five genes was more frequent in EBVaGC than in EBVnGC (p < 0.05). p16 and FHIT methylation was reversely correlated with protein expression in EBVaGC. Most (41/49) EBVaGC exhibited CIMP-high (CIMP-H), and the prognosis of CIMP-H patients was significantly worse than that of CIMP-low (p = 0.027) and CIMP-none (p = 0.003) patients. Treatment with 5-aza-dC and/or TSA induced upregulation of RNA expression of all five genes in SNU-719; meanwhile, individual gene expression increased in EBVnGC cell lines. In summary, EBV-induced hypermethylation of p16, FHIT, CRBP1, WWOX, and DLC-1 may contribute to EBVaGC development. Demethylation therapy may represent a novel therapeutic strategy for EBVaGC.

Conway K, Edmiston SN, May R, et al.
DNA methylation profiling in the Carolina Breast Cancer Study defines cancer subclasses differing in clinicopathologic characteristics and survival.
Breast Cancer Res. 2014; 16(5):450 [PubMed] Free Access to Full Article Related Publications
INTRODUCTION: Breast cancer is a heterogeneous disease, with several intrinsic subtypes differing by hormone receptor (HR) status, molecular profiles, and prognosis. However, the role of DNA methylation in breast cancer development and progression and its relationship with the intrinsic tumor subtypes are not fully understood.
METHODS: A microarray targeting promoters of cancer-related genes was used to evaluate DNA methylation at 935 CpG sites in 517 breast tumors from the Carolina Breast Cancer Study, a population-based study of invasive breast cancer.
RESULTS: Consensus clustering using methylation (β) values for the 167 most variant CpG loci defined four clusters differing most distinctly in HR status, intrinsic subtype (luminal versus basal-like), and p53 mutation status. Supervised analyses for HR status, subtype, and p53 status identified 266 differentially methylated CpG loci with considerable overlap. Genes relatively hypermethylated in HR+, luminal A, or p53 wild-type breast cancers included FABP3, FGF2, FZD9, GAS7, HDAC9, HOXA11, MME, PAX6, POMC, PTGS2, RASSF1, RBP1, and SCGB3A1, whereas those more highly methylated in HR-, basal-like, or p53 mutant tumors included BCR, C4B, DAB2IP, MEST, RARA, SEPT5, TFF1, THY1, and SERPINA5. Clustering also defined a hypermethylated luminal-enriched tumor cluster 3 that gene ontology analysis revealed to be enriched for homeobox and other developmental genes (ASCL2, DLK1, EYA4, GAS7, HOXA5, HOXA9, HOXB13, IHH, IPF1, ISL1, PAX6, TBX1, SOX1, and SOX17). Although basal-enriched cluster 2 showed worse short-term survival, the luminal-enriched cluster 3 showed worse long-term survival but was not independently prognostic in multivariate Cox proportional hazard analysis, likely due to the mostly early stage cases in this dataset.
CONCLUSIONS: This study demonstrates that epigenetic patterns are strongly associated with HR status, subtype, and p53 mutation status and may show heterogeneity within tumor subclass. Among HR+ breast tumors, a subset exhibiting a gene signature characterized by hypermethylation of developmental genes and poorer clinicopathologic features may have prognostic value and requires further study. Genes differentially methylated between clinically important tumor subsets have roles in differentiation, development, and tumor growth and may be critical to establishing and maintaining tumor phenotypes and clinical outcomes.

Doldo E, Costanza G, Ferlosio A, et al.
CRBP-1 expression in ovarian cancer: a potential therapeutic target.
Anticancer Res. 2014; 34(7):3303-12 [PubMed] Related Publications
BACKGROUND/AIM: Cellular retinol binding protein-1 regulates retinol bioavailability and contributes to cell differentiation maintenance, but its role in ovarian carcinogenesis remains uncertain. We investigated CRBP-1 expression in ovarian tumors and CRBP-1 signaling-regulated pathways.
MATERIALS AND METHODS: We performed immunohistochemistry, methylation-specific PCR, gene copy number analysis in ovarian tumors and proliferation/apoptosis evaluation, gene array, blot and real-time PCR in CRBP-1-transfected A2780 ovarian cancer cells.
RESULTS: CRBP-1 expression was reduced or absent in G2 and G3 ovarian carcinomas. CRBP-1 silencing in 60% of G2 and 66.7% of G3 carcinomas was due to CRBP-1 promoter methylation. A2780 CRBP-1-transfected cells showed increased retinol-induced apoptosis, retinoid-induced reduced clonogenicity and down-regulation of proliferation and transcription genes, including AKT1, AKT3, EGFR, FOS, JUN, STAT1 and STAT5A.
CONCLUSION: CRBP-1 loss in G2/G3 ovarian carcinomas and increased apoptotic susceptibility to retinoids in CRBP-1-transfected-A2780 cells suggest CRBP-1 screening as a target to ensure efficacy of an adjuvant retinoid therapy.

Chan AW, Tong JH, Sung MY, et al.
Epstein-Barr virus-associated lymphoepithelioma-like cholangiocarcinoma: a rare variant of intrahepatic cholangiocarcinoma with favourable outcome.
Histopathology. 2014; 65(5):674-83 [PubMed] Related Publications
AIMS: Lymphoepithelioma-like cholangiocarcinoma (LELCC) is a rare variant of intrahepatic cholangiocarcinoma (IHCC). Only 16 cases have reported previously in the literature, and about 62.5% of these cases were associated with Epstein-Barr virus (EBV).
METHODS AND RESULTS: We present the largest series (seven cases) of LELCC with descriptions of clinical and pathological characteristics, investigations of aberrant DNA methylation and mutation analyses of EGFR and KRAS. The evaluation also included 11 cases of stage-matched conventional IHCC for comparison.
RESULTS: All seven patients of LELCC were female and had stage I disease. LELCC had significantly better 2- and 5-year overall survival than IHCC (100% versus 52.8%, and 100% versus 13.2%, respectively, P = 0.003). All seven LELCCs were EBV-associated and composed exclusively of adenocarcinoma with varied glandular differentiation, dense lymphoplasmacytic infiltrate, and variable expression of biliary-type cytokeratins (CK7 and CK19) and stemness markers (CD133 and EpCAM). Gene hypermethylation was more frequent in LELCC than IHCC. CRBPI (85.7% versus 9.1%, P < 0.003) and CRBPIV (85.7% versus 0%, P < 0.001) showed statistically higher methylation frequencies in LELCC than IHCC. No LELCC harboured any EGFR or KRAS mutation.
CONCLUSION: Epstein-Barr virus-associated LELCC is a variant of IHCC, characterized by marked female predominance, favourable overall survival and distinctively frequent DNA hypermethylation.

Kainov Y, Favorskaya I, Delektorskaya V, et al.
CRABP1 provides high malignancy of transformed mesenchymal cells and contributes to the pathogenesis of mesenchymal and neuroendocrine tumors.
Cell Cycle. 2014; 13(10):1530-9 [PubMed] Free Access to Full Article Related Publications
CRABP1 (cellular retinoic acid binding protein 1) belongs to the family of fatty acid binding proteins. Retinoic acid binding is the only known functional activity of this protein. The role of CRABP1 in human carcinogenesis remains poorly understood. Here, for the first time we demonstrated pro-metastatic and pro-tumorigenic activity of CRABP1 in mesenchymal tumors. Further functional analysis revealed that the pro-tumorigenic effect of CRABP1 does not depend on retinoic acid binding activity. These results suggest that CRABP1 could have an alternative intracellular functional activity that contributes to the high malignancy of transformed mesenchymal cells. Microarray analysis detected CRABP1-mediated alterations in the expression of about 100 genes, including those encoding key regulatory proteins. CRABP1 is ubiquitously expressed in monophasic synovial sarcomas, while in biphasic synovial sarcomas it is expressed uniquely by the spindle cells of the aggressive mesenchymal component. High level of CRABP1 expression is associated with lymph node metastasis and poor differentiation/high grade of pancreatic neuroendocrine tumors (pNETs). Presented data suggest CRABP1 as a promising biomarker of pNETs' clinical behavior. Our results give the first evidence of pro-tumorigenic and pro-metastatic activity of CRABP1 in mesenchymal and neuroendocrine tumors.

McCready J, Arendt LM, Glover E, et al.
Pregnancy-associated breast cancers are driven by differences in adipose stromal cells present during lactation.
Breast Cancer Res. 2014; 16(1):R2 [PubMed] Free Access to Full Article Related Publications
INTRODUCTION: The prognosis of breast cancer is strongly influenced by the developmental stage of the breast when the tumor is diagnosed. Pregnancy-associated breast cancers (PABCs), cancers diagnosed during pregnancy, lactation, or in the first postpartum year, are typically found at an advanced stage, are more aggressive and have a poorer prognosis. Although the systemic and microenvironmental changes that occur during post-partum involution have been best recognized for their role in the pathogenesis of PABCs, epidemiological data indicate that PABCs diagnosed during lactation have an overall poorer prognosis than those diagnosed during involution. Thus, the physiologic and/or biological events during lactation may have a significant and unrecognized role in the pathobiology of PABCs.
METHODS: Syngeneic in vivo mouse models of PABC were used to examine the effects of system and stromal factors during pregnancy, lactation and involution on mammary tumorigenesis. Mammary adipose stromal cell (ASC) populations were isolated from mammary glands and examined by using a combination of in vitro and in vivo functional assays, gene expression analysis, and molecular and cellular assays. Specific findings were further investigated by immunohistochemistry in mammary glands of mice as well as in functional studies using ASCs from lactating mammary glands. Additional findings were further investigated using human clinical samples, human stromal cells and using in vivo xenograft assays.
RESULTS: ASCs present during lactation (ASC-Ls), but not during other mammary developmental stages, promote the growth of carcinoma cells and angiogenesis. ASCs-Ls are distinguished by their elevated expression of cellular retinoic acid binding protein-1 (crabp1), which regulates their ability to retain lipid. Human breast carcinoma-associated fibroblasts (CAFs) exhibit traits of ASC-Ls and express crabp1. Inhibition of crabp1in CAFs or in ASC-Ls abolished their tumor-promoting activity and also restored their ability to accumulate lipid.
CONCLUSIONS: These findings imply that (1) PABC is a complex disease, which likely has different etiologies when diagnosed during different stages of pregnancy; (2) both systemic and local factors are important for the pathobiology of PABCs; and (3) the stromal changes during lactation play a distinct and important role in the etiology and pathogenesis of PABCs that differ from those during post-lactational involution.

Jiao TT, Zhang YM, Yao L, et al.
Importance of spondin 1 and cellular retinoic acid binding protein 1 in the clinical diagnosis of ovarian cancer.
Int J Clin Exp Pathol. 2013; 6(12):3036-41 [PubMed] Free Access to Full Article Related Publications
BACKGROUND: Diagnosis of ovarian cancer is often delayed because of subtle symptoms and a lack of a specific, sensitive test useful for the general population. The majority of cases are diagnosed at late stages, after the tumor has metastasized and implanted on many other abdominal organs and cavity surfaces. A paucity of prognostic markers makes it difficult to define which tumors will act aggressively and shorten survival. Hence, it is imperative to have new screening tests for diagnosis of ovarian cancer at earlier stages, prior to metastatic progression. Diagnosis at these early stages will dramatically increase the overall survival of women with ovarian cancer.
MATERIAL AND METHODS: Based on previously published literature on proposed molecular cell markers in ovarian carcinoma, we sought to validate the overexpression of two genes (cellular retinoic acid Binding Protein, CRABP-1, and spondin 1) through immunohistochemistry.
RESULTS: We verified the overexpression of spondin 1 in ovarian cancer. Expression of cellular retinoic acid Binding Protein, CRABP-1 in whole ovarian cancer tissue sections was higher than in the TMA tissue cores.
CONCLUSION: Our results thus demonstrate that spondin 1 is a useful marker for ovarian cancer; additionally, the high percentages of tumors that are positive for spondin 1 make it an ideal target for therapy. CRABP-1 was not expressed at high levels in any subtype of ovarian cancer, making it a poor marker.

Honecker F, Rohlfing T, Harder S, et al.
Proteome analysis of the effects of all-trans retinoic acid on human germ cell tumor cell lines.
J Proteomics. 2014; 96:300-13 [PubMed] Related Publications
UNLABELLED: We analysed the effects of all-trans retinoic acid (ATRA) on proliferation and changes in the global proteome of the nullipotent human embryonal carcinoma cell line 2102Ep and the pluripotent cell line NTERA2 cl.D1 (NT2). Differentially expressed proteins were assessed by 2D-PAGE and mass spectrometry, followed by verification and analysis of protein modifications of proteins of the retinoid pathway. We established a proteome map of the germ cell tumor (GCT) cell line NT2 showing neuronal differentiation under ATRA treatment for 7days. Using bioinformatic analyses, we identified functional groups of altered proteins and potentially involved pathways, of which changes to the organization of the cytoskeleton and anti-apoptotic effects were the most prominent. Changes observed in the expression of factors involved in the retinoid pathway under ATRA, namely an upregulation of CRBP and CRABP2, were also reflected in GCT tissues of different histologies, providing further insight into factors involved in the differentiation of these pluripotent tumors.
BIOLOGICAL SIGNIFICANCE: Treatment of NT2 germ cell tumor cells with all-trans retinoic acid (ATRA) is a model to investigate differentiation. We analysed differentially expressed proteins by 2D-PAGE and mass spectrometry and provide a proteome map of NT2 cells under 7days of ATRA. By bioinformatic analyses, functional groups of proteins and involved pathways like changes to the cytoskeleton and anti-apoptotic effects were identified. Factors involved in the retinoid pathway, in particular upregulation of CRBP, CRABP1 and CRABP2, also showed differential expression in tumors with different histological subtypes, which provides insight into gene regulation under induced and spontaneous differentiation in germ cell tumors.

Mendoza-Rodriguez M, Arreola H, Valdivia A, et al.
Cellular retinol binding protein 1 could be a tumor suppressor gene in cervical cancer.
Int J Clin Exp Pathol. 2013; 6(9):1817-25 [PubMed] Free Access to Full Article Related Publications
AIMS: Cervical Cancer (CC) is one of the most important health problems in women. It frequently presents genetic changes at chromosome region 3q21. This region contains the Cellular Retinol Binding Protein 1 gene (CRBP1) which has been implicated as an important element in the development of other types of cancer. The main goal of the present work was to determine the molecular alterations of CRBP1 and its relationship to CC.
METHODS: To determine the molecular alterations of CRBP1 gene in CC; twenty-six CC and twenty-six healthy cervix samples were evaluated for: 1) Copy number gain by real-time PCR analysis, 2) expression levels by an immunohistochemistry assay on tissue microarray, and 3) the methylation status of the CRBP1 promoter region.
RESULTS: The increase in CRBP1 copy number was observed in 10 out of the 26 CC samples analyzed, while healthy cervices samples showed no changes in the copy number. In addition, there was a lack of expression of the CRBP1 gene in an important number of the CC samples (17/26), and the CRBP1 gene promoter was methylated in 15/26 of the CC samples. Interestingly, there was a significant association between the lack of expression of the CRBP1 gene and its methylation status.
CONCLUSIONS: The data indicates that, both activating and inactivating changes in the CRBP1 gene could be significant events in the development and progression of CC, and the lack of expression of the CRBP1 protein could be related with to the development of CC. We believe that there is enough evidence to consider to CRBP1 gene as a tumor suppressor gene for CC.

Kim SJ, Sohn I, Do IG, et al.
Gene expression profiles for the prediction of progression-free survival in diffuse large B cell lymphoma: results of a DASL assay.
Ann Hematol. 2014; 93(3):437-47 [PubMed] Related Publications
We performed the whole genome cDNA-mediated annealing, selection and ligation assay with 164 formalin-fixed paraffin-embedded (FFPE) tumor samples to develop robust prognostic gene expression profiles in patients with diffuse large B cell lymphoma. The prognostic gene expression profiles were developed and validated by a gradient lasso and leave-one-out cross-validation process. We identified a set of genes whose expression provided prognostic indicators from whole data set (PRKCDBP, CASP10, FAM3C, KCNK12, MAN1A2, PRND, RAB1A, TMEM39B, SLC6A6, MMP12, FEM1B, C3orh37, RBP1, HK1, LOC400464, KIAA0746, and SLC25A23). This gene expression profile-based risk model could classify patients into two cross-validated risk groups with a significant difference in 5-year progression-free survival rates (71.1 vs. 45.5 %) and with a hazard ratio for recurrence of 2.45 (95 % CI, 1.44-4.16, P = 0.001). This model provided prognostic information independent of the International Prognostic Index (IPI), and discriminated high-risk group from patients belong to high/high-intermediate risk of IPI and activated B cell-like type. Thus, gene expression profiling from FFPE could provide additional prognostic information for diffuse large B cell lymphoma and our data underscore the need for development of risk-adapted treatment strategies based on gene expression profiles.

Sintupisut N, Liu PL, Yeang CH
An integrative characterization of recurrent molecular aberrations in glioblastoma genomes.
Nucleic Acids Res. 2013; 41(19):8803-21 [PubMed] Free Access to Full Article Related Publications
Glioblastoma multiforme (GBM) is the most common and malignant primary brain tumor in adults. Decades of investigations and the recent effort of the Cancer Genome Atlas (TCGA) project have mapped many molecular alterations in GBM cells. Alterations on DNAs may dysregulate gene expressions and drive malignancy of tumors. It is thus important to uncover causal and statistical dependency between 'effector' molecular aberrations and 'target' gene expressions in GBMs. A rich collection of prior studies attempted to combine copy number variation (CNV) and mRNA expression data. However, systematic methods to integrate multiple types of cancer genomic data-gene mutations, single nucleotide polymorphisms, CNVs, DNA methylations, mRNA and microRNA expressions and clinical information-are relatively scarce. We proposed an algorithm to build 'association modules' linking effector molecular aberrations and target gene expressions and applied the module-finding algorithm to the integrated TCGA GBM data sets. The inferred association modules were validated by six tests using external information and datasets of central nervous system tumors: (i) indication of prognostic effects among patients; (ii) coherence of target gene expressions; (iii) retention of effector-target associations in external data sets; (iv) recurrence of effector molecular aberrations in GBM; (v) functional enrichment of target genes; and (vi) co-citations between effectors and targets. Modules associated with well-known molecular aberrations of GBM-such as chromosome 7 amplifications, chromosome 10 deletions, EGFR and NF1 mutations-passed the majority of the validation tests. Furthermore, several modules associated with less well-reported molecular aberrations-such as chromosome 11 CNVs, CD40, PLXNB1 and GSTM1 methylations, and mir-21 expressions-were also validated by external information. In particular, modules constituting trans-acting effects with chromosome 11 CNVs and cis-acting effects with chromosome 10 CNVs manifested strong negative and positive associations with survival times in brain tumors. By aligning the information of association modules with the established GBM subclasses based on transcription or methylation levels, we found each subclass possessed multiple concurrent molecular aberrations. Furthermore, the joint molecular characteristics derived from 16 association modules had prognostic power not explained away by the strong biomarker of CpG island methylator phenotypes. Functional and survival analyses indicated that immune/inflammatory responses and epithelial-mesenchymal transitions were among the most important determining processes of prognosis. Finally, we demonstrated that certain molecular aberrations uniquely recurred in GBM but were relatively rare in non-GBM glioma cells. These results justify the utility of an integrative analysis on cancer genomes and provide testable characterizations of driver aberration events in GBM.

Kaiser MF, Johnson DC, Wu P, et al.
Global methylation analysis identifies prognostically important epigenetically inactivated tumor suppressor genes in multiple myeloma.
Blood. 2013; 122(2):219-26 [PubMed] Free Access to Full Article Related Publications
Outcome in multiple myeloma is highly variable and a better understanding of the factors that influence disease biology is essential to understand and predict behavior in individual patients. In the present study, we analyzed combined genomewide DNA methylation and gene expression data of patients treated in the Medical Research Council Myeloma IX trial. We used these data to identify epigenetically repressed tumor suppressor genes with prognostic relevance in myeloma. We identified 195 genes with changes in methylation status that were significantly associated with prognosis. Combining DNA methylation and gene expression data led to the identification of the epigenetically regulated tumor modulating genes GPX3, RBP1, SPARC, and TGFBI. Hypermethylation of these genes was associated with significantly shorter overall survival, independent of age, International Staging System score, and adverse cytogenetics. The 4 differentially methylated and expressed genes are known to mediate important tumor suppressive functions including response to chemotherapy (TGFBI), interaction with the microenvironment (SPARC), retinoic acid signaling (RBP1), and the response to oxidative stress (GPX3), which could explain the prognostic impact of their differential methylation. Assessment of the DNA methylation status of the identified genes could contribute to the molecular characterization of myeloma, which is prerequisite for an individualized treatment approach.

Qu Y, Dang S, Hou P
Gene methylation in gastric cancer.
Clin Chim Acta. 2013; 424:53-65 [PubMed] Related Publications
Gastric cancer is one of the most common malignancies and remains the second leading cause of cancer-related death worldwide. Over 70% of new cases and deaths occur in developing countries. In the early years of the molecular biology revolution, cancer research mainly focuses on genetic alterations, including gastric cancer. Epigenetic mechanisms are essential for normal development and maintenance of tissue-specific gene expression patterns in mammals. Disruption of epigenetic processes can lead to altered gene function and malignant cellular transformation. Recent advancements in the rapidly evolving field of cancer epigenetics have shown extensive reprogramming of every component of the epigenetic machinery in cancer, including DNA methylation, histone modifications, nucleosome positioning, noncoding RNAs, and microRNAs. Aberrant DNA methylation in the promoter regions of gene, which leads to inactivation of tumor suppressor and other cancer-related genes in cancer cells, is the most well-defined epigenetic hallmark in gastric cancer. The advantages of gene methylation as a target for detection and diagnosis of cancer in biopsy specimens and non-invasive body fluids such as serum and gastric washes have led to many studies of application in gastric cancer. This review focuses on the most common and important phenomenon of epigenetics, DNA methylation, in gastric cancer and illustrates the impact epigenetics has had on this field.

Gauchotte G, Lacomme S, Brochin L, et al.
Retinoid acid receptor expression is helpful to distinguish between adenoma and well-differentiated carcinoma in the thyroid.
Virchows Arch. 2013; 462(6):619-32 [PubMed] Related Publications
Retinoid receptors (RRs) play a key role in cell proliferation and differentiation. We characterized the expression of RA receptors and retinoid X receptors (RARs and RXRs) in a series of 111 thyroid tumors and investigated the mechanisms responsible for their deregulation: hypermethylation of the RARB2 promoter, loss of heterozygosity (LOH) in the regions of RARB and RXRA, and altered expression of CRBP1 and enzymes involved in RA biosynthesis (RDH10 and RALDH2). Expression of RALDH2 and RDH10 was conserved in 100 % of adenomas and in 90 and 98 %, respectively, of carcinomas, whereas staining for CRBP1 was decreased in 9 % of FAs and 28 % of carcinomas, mainly anaplastic carcinomas (55 %). We found an abnormal expression of RARA, RARB, RXRA, and RXRB in 67, 69, 66, and 73 %, respectively, of thyroid carcinomas (n = 78) and in 9, 9, 9, and 33 % of follicular adenomas (n = 33) (p < 0.001). An abnormal staining pattern of at least two of these markers had 90 % sensitivity and 91 % specificity for a diagnosis of malignancy. Promoter hypermethylation of RARB2 was observed in some anaplastic carcinomas (14 %). LOH was found to be common at the RARB locus (3p24-3p25) and the RXRA locus (9q34), respectively, in 44 and 55 % of carcinomas and in 27 and 43 % of adenomas. In conclusion, immunohistochemical staining for RARs and RXRs may help in the differential diagnosis between well-differentiated carcinoma and follicular adenoma. Further investigation should be carried out to determine whether the characterization of RR expression might identify patients who could benefit from therapy with RA derivatives.

Honda M, Yamashita T, Yamashita T, et al.
Peretinoin, an acyclic retinoid, improves the hepatic gene signature of chronic hepatitis C following curative therapy of hepatocellular carcinoma.
BMC Cancer. 2013; 13:191 [PubMed] Free Access to Full Article Related Publications
BACKGROUND: The acyclic retinoid, peretinoin, has been shown to be effective for suppressing hepatocellular carcinoma (HCC) recurrence after definitive treatment in a small-scale randomized clinical trial. However, little has been documented about the mechanism by which peretinoin exerts its inhibitory effects against recurrent HCC in humans in vivo.
METHODS: Twelve hepatitis C virus-positive patients whose HCC had been eradicated through curative resection or ablation underwent liver biopsy at baseline and week 8 of treatment with either a daily dose of 300 or 600 mg peretinoin. RNA isolated from biopsy samples was subjected to gene expression profile analysis.
RESULTS: Peretinoin treatment elevated the expression levels of IGFBP6, RBP1, PRB4, CEBPA, G0S2, TGM2, GPRC5A, CYP26B1, and many other retinoid target genes. Elevated expression was also observed for interferon-, Wnt-, and tumor suppressor-related genes. By contrast, decreased expression levels were found for mTOR- and tumor progression-related genes. Interestingly, gene expression profiles for week 8 of peretinoin treatment could be classified into two groups of recurrence and non-recurrence with a prediction accuracy rate of 79.6% (P<0.05). In the liver of patients with non-recurrence, expression of PDGFC and other angiogenesis genes, cancer stem cell marker genes, and genes related to tumor progression was down-regulated, while expression of genes related to hepatocyte differentiation, tumor suppression genes, and other genes related to apoptosis induction was up-regulated.
CONCLUSIONS: Gene expression profiling at week 8 of peretinoin treatment could successfully predict HCC recurrence within 2 years. This study is the first to show the effect of peretinoin in suppressing HCC recurrence in vivo based on gene expression profiles and provides a molecular basis for understanding the efficacy of peretinoin.

Chou AP, Chowdhury R, Li S, et al.
Identification of retinol binding protein 1 promoter hypermethylation in isocitrate dehydrogenase 1 and 2 mutant gliomas.
J Natl Cancer Inst. 2012; 104(19):1458-69 [PubMed] Free Access to Full Article Related Publications
BACKGROUND: Mutations in isocitrate dehydrogenase 1 (IDH1) and associated CpG island hypermethylation represent early events in the development of low-grade gliomas and secondary glioblastomas. To identify candidate tumor suppressor genes whose promoter methylation may contribute to gliomagenesis, we compared methylation profiles of IDH1 mutant (MUT) and IDH1 wild-type (WT) tumors using massively parallel reduced representation bisulfite sequencing.
METHODS: Reduced representation bisulfite sequencing was performed on ten pathologically matched WT and MUT glioma samples and compared with data from a methylation-sensitive restriction enzyme technique and data from The Cancer Genome Atlas (TCGA). Methylation in the gene retinol-binding protein 1 (RBP1) was identified in IDH1 mutant tumors and further analyzed with primer-based bisulfite sequencing. Correlation between IDH1/IDH2 mutation status and RBP1 methylation was evaluated with Spearman correlation. Survival data were collected retrospectively and analyzed with Kaplan-Meier and Cox proportional hazards analysis. All statistical tests were two-sided.
RESULTS: Methylome analysis identified coordinated CpG island hypermethylation in IDH1 MUT gliomas, consistent with previous reports. RBP1, important in retinoic acid metabolism, was found to be hypermethylated in 76 of 79 IDH1 MUT, 3 of 3 IDH2 MUT, and 0 of 116 IDH1/IDH2 WT tumors. IDH1/IDH2 mutation was highly correlated with RBP1 hypermethylation (n = 198; Spearman R = 0.94, 95% confidence interval = 0.92 to 0.95, P < .001). The Cancer Genome Atlas showed IDH1 MUT tumors (n = 23) to be RBP1-hypermethylated with decreased RBP1 expression compared with WT tumors (n = 124). Among patients with primary glioblastoma, patients with RBP1-unmethylated tumors (n = 102) had decreased median overall survival compared with patients with RBP1-methylated tumors (n = 22) (20.3 months vs 36.8 months, respectively; hazard ratio of death = 2.48, 95% confidence interval = 1.30 to 4.75, P = .006).
CONCLUSION: RBP1 promoter hypermethylation is found in nearly all IDH1 and IDH2 mutant gliomas and is associated with improved patient survival. Because RBP1 is involved in retinoic acid synthesis, our results suggest that dysregulation of retinoic acid metabolism may contribute to glioma formation along the IDH1/IDH2-mutant pathway.

Manzo SG, Zhou ZL, Wang YQ, et al.
Natural product triptolide mediates cancer cell death by triggering CDK7-dependent degradation of RNA polymerase II.
Cancer Res. 2012; 72(20):5363-73 [PubMed] Related Publications
Triptolide is a bioactive ingredient in traditional Chinese medicine that exhibits diverse biologic properties, including anticancer properties. Among its many putative targets, this compound has been reported to bind to XPB, the largest subunit of general transcription factor TFIIH, and to cause degradation of the largest subunit Rpb1 of RNA polymerase II (RNAPII). In this study, we clarify multiple important questions concerning the significance and basis for triptolide action at this core target. Triptolide decreased Rpb1 levels in cancer cells in a manner that was correlated tightly with its cytotoxic activity. Compound exposure blocked RNAPII at promoters and decreased chromatin-bound RNAPII, both upstream and within all genes that were examined, also leading to Ser-5 hyperphosphorylation and increased ubiqutination within the Rbp1 carboxy-terminal domain. Notably, cotreatment with inhibitors of the proteasome or the cyclin-dependent kinase CDK7 inhibitors abolished the ability of triptolide to ablate Rpb1. Together, our results show that triptolide triggers a CDK7-mediated degradation of RNAPII that may offer an explanation to many of its therapeutic properties, including its robust and promising anticancer properties.

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