Research IndicatorsGraph generated 01 September 2019 using data from PubMed using criteria.
Mouse over the terms for more detail; many indicate links which you can click for dedicated pages about the topic. Tag cloud generated 01 September, 2019 using data from PubMed, MeSH and CancerIndex
Specific Cancers (1)
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).
OMIM, Johns Hopkin University
Referenced article focusing on the relationship between phenotype and genotype.
International Cancer Genome Consortium.
Summary of gene and mutations by cancer type from ICGC
Cancer Genome Anatomy Project, NCI
COSMIC, Sanger Institute
Somatic mutation information and related details
GEO Profiles, NCBI
Search the gene expression profiles from curated DataSets in the Gene Expression Omnibus (GEO) repository.
Latest Publications: ABCC5 (cancer-related)
BACKGROUND: Oxaliplatin resistance is a major challenge for treatment of advanced colorectal cancer (CRC). Both acquisition of epithelial-mesenchymal transition (EMT) and suppressed drug accumulation in cancer cells contributes to development of oxaliplatin resistance. Aberrant expression of small noncoding RNA, miR-128-3p, has been shown to be a key regulator in tumorigenesis and cancer development. However, its roles in the progression of CRC and oxaliplatin-resistance are largely unknown.
METHODS: Oxaliplatin-resistant CRC and normal intestinal FHC cells were transfected with a miR-128-3p expression lentivirus. After transfection, FHC-derived exosomes were isolated and co-cultured with CRC cells. miR-128-3p expression in resistant CRC cells, FHC cells, and exosomes was quantified by quantitative real-time PCR (RT-qPCR). The mRNA and protein levels of miR-128-3p target genes in resistant CRC cells were quantified by RT-qPCR and western blot, respectively. The effects of miR-128-3p on CRC cell viability, apoptosis, EMT, motility and drug efflux were evaluated by CCK8, flow cytometry, Transwell and wound healing assays, immunofluorescence, and atomic absorption spectrophotometry. Xenograft models were used to determine whether miR-128-3p loaded exosomes can re-sensitize CRC cells to oxaliplatin in vivo.
RESULTS: In our established stable oxaliplatin-resistant CRC cell lines, in vitro and vivo studies revealed miR-128-3p suppressed EMT and increased intracellular oxaliplatin accumulation. Importantly, our results indicated that lower miR-128-3p expression was associated with poor oxaliplatin response in advanced human CRC patients. Moreover, data showed that miR-128-3p-transfected FHC cells effectively packaged miR-128-3p into secreted exosomes and mediated miR-128-3p delivery to oxaliplatin-resistant cells, improving oxaliplatin response in CRC cells both in vitro and in vivo. In addition, miR-128-3p overexpression up-regulated E-cadherin levels and inhibited oxaliplatin-induced EMT by suppressing Bmi1 expression in resistant cells. Meanwhile, it also decreased oxaliplatin efflux through suppressed expression of the drug transporter MRP5.
CONCLUSION: Our results demonstrate that miR-128-3p delivery via exosomes represents a novel strategy enhancing chemosensitivity in CRC through negative regulation of Bmi1 and MRP5. Moreover, miR-128-3p may be a promising diagnostic and prognostic marker for oxaliplatin-based chemotherapy.
Salvador-Martín S, García-González X, García MI, et al.Clinical utility of ABCB1 genotyping for preventing toxicity in treatment with irinotecan.
Pharmacol Res. 2018; 136:133-139 [PubMed
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Preventing severe irinotecan-induced adverse reactions would allow us to offer better treatment and improve patients' quality of life. Transporters, metabolizing enzymes, and genes involved in the folate pathway have been associated with irinotecan-induced toxicity. We analyzed 12 polymorphisms in UGT1A1, ABCB1, ABCG2, ABCC4, ABCC5, and MTHFR in 158 patients with metastatic colorectal cancer treated with irinotecan and studied the association with grade >2 adverse reactions (CTCAE). Among the most frequent ADRs, the SNPs rs1128503, rs2032582, and rs1045642 in ABCB1 and rs1801133 in MTHFR were associated with hematological toxicity and overall toxicity. The SNP rs11568678 in ABCC4 was also associated with overall toxicity. After correction of P values using a false discovery rate, only ABCB1 variants remained statistically significant. Haplotype analysis in ABCB1 showed an 11.3-fold and 4.6-fold increased risk of hematological toxicity (95% CI, 1.459-88.622) and overall toxicity (95% CI, 2.283-9.386), respectively. Consequently, genotyping of the three SNPs in ABCB1 can predict overall toxicity and hematological toxicity with a diagnostic odds ratio of 4.40 and 9.94, respectively. Genotyping of ABCB1 variants can help to prevent severe adverse reactions to irinotecan-based treatments in colorectal cancer.
Hu H, Yang L, Li L, Zeng CLong non-coding RNA KCNQ1OT1 modulates oxaliplatin resistance in hepatocellular carcinoma through miR-7-5p/ ABCC1 axis.
Biochem Biophys Res Commun. 2018; 503(4):2400-2406 [PubMed
] Related Publications
The underlying functions of long non-coding RNAs (lncRNAs) on chemoresistance in multiple cancers have been testified. However, the function and mechanism of lncRNAs on chemoresistance in hepatocellular carcinoma are still confused. In this study, we concentrated on the function and mechanism of KCNQ1OT1 on oxaliplatin resistance in hepatocellular carcinoma. Results showed that KCNQ1OT1 was significantly up-regulated in oxaliplatin-resistant HepG2 and Huh7 cells. Moreover, knockdown of KCNQ1OT1 inhibited the cell proliferation, migration, invasion and reduced the expression of drug-resistant gene (MRP5, MDR1, LRP1). Additionally, bioinformatics analysis and dual-luciferase reporter assay showed that miR-7-5p directly targeted the 3'-UTR of miR-7-5p and ABCC1 mRNA, indicating that KCNQ1OT1 regulated the expression of ABCC1 via endogenous sponging miR-7-5p. Conclusively, KCNQ1OT1 modulated oxaliplatin resistance in hepatocellular carcinoma through miR-7-5p/ABCC1 axis, indicating a novel approach for the treatment of hepatocellular carcinoma.
Han Z, Shi LLong non-coding RNA LUCAT1 modulates methotrexate resistance in osteosarcoma via miR-200c/ABCB1 axis.
Biochem Biophys Res Commun. 2018; 495(1):947-953 [PubMed
] Related Publications
Long non-coding RNAs (lncRNAs) have been verified to participate in the tumorigenesis of multiple cancers. Nevertheless, the deepgoing role molecular mechanisms of lncRNAs on osteosarcoma chemoresistance remain unclear. In present study, we investigate the function of lncRNA LUCAT1 on osteosarcoma methotrexate (MTX) resistant phenotype and discover the potential regulatory mechanism. Results showed that LUCAT1 was up-regulated in MTX-resistant cells (MG63/MTX, HOS/MTX) compared to that in parental cells. LncRNA LUCAT1 and ABCB1 protein expression levels were both up-regulated when induced by different concentration of methotrexate. In vitro and vivo, LUCAT1 knockdown decreased the expression levels drug resistance related genes (MDR1, MRP5, LRP1), proliferation, invasion and tumor growth of osteosarcoma cells. Bioinformatics tools and luciferase assay reveled that miR-200c both targeted the 3'-UTR of LUCAT1 and ABCB1 mRNA, suggesting the modulation of LUCAT1 on ABCB1 through sponging miR-200c. Rescue experiments confirmed the combined role of LUCAT1, miR-200c and ABCB1 on osteosarcoma proliferation, invasion and methotrexate resistance. Overall, results indicate the vital role of LUCAT1 in the methotrexate resistance regulation through miR-200c/ABCB1 pathway, providing a novel insight and treatment strategy for osteosarcoma drug resistance.
Burt BM, Lee HS, Lenge De Rosen V, et al.Soluble Mesothelin-Related Peptides to Monitor Recurrence After Resection of Pleural Mesothelioma.
Ann Thorac Surg. 2017; 104(5):1679-1687 [PubMed
] Related Publications
BACKGROUND: Most patients undergoing surgical resection of malignant pleural mesothelioma (MPM) will experience recurrence, and radiographic diagnosis of recurrence can be difficult in the postoperative chest. Our objective was to determine the utility of the serum biomarker soluble mesothelin-related peptide (SMRP; or mesothelin) in monitoring of the postoperative MPM patient.
METHODS: We retrospectively evaluated a prospectively maintained single institution clinical database. SMRP levels were evaluated preoperatively and postoperatively in patients undergoing surgical resection of MPM.
RESULTS: One hundred two patients underwent pleurectomy/decortication (58%), extrapleural pneumonectomy (20%), chest wall resection (2%), or exploratory thoracotomy (20%) for MPM of 81% epithelial histology. Sixty percent received heated intraoperative chemotherapy and 57% received perioperative systemic chemotherapy. Patients with epithelial histology had substantially greater mean (± SD) preoperative SMRP levels (4.5 ± 7.3 nmol/L) than did patients with biphasic (1.9 ± 2.5 nmol/L) or sarcomatoid (1.2 ± 1.0 nmol/L) histology. Radiologic 3-dimensional tumor volume and tumor mesothelin gene (MSLN) expression correlated with preoperative SMRP. In patients with epithelial histology undergoing complete resection (n = 66), preoperative SMRP (3.4 ± 4.9 nmol/L) dramatically decreased immediately after operation (0.8 ± 0.5 nmol/L), and preoperative SMRP was independently associated with poor disease-free survival. Percentage of change in serial postoperative SMRP values at the best statistical cutoff at 48% revealed high predictive capability of disease recurrence with 90% sensitivity and 93% specificity (area under the curve = 0.96, p < 0.001).
CONCLUSIONS: SMRP is a promising serum biomarker for the detection of recurrence after resection of epithelial MPM that may have value in clinical practice and should be studied in a prospective cohort.
Li H, Yuan X, Yan D, et al.Long Non-Coding RNA MALAT1 Decreases the Sensitivity of Resistant Glioblastoma Cell Lines to Temozolomide.
Cell Physiol Biochem. 2017; 42(3):1192-1201 [PubMed
] Related Publications
BACKGROUND/AIM: Multidrug resistance (MDR) is largely responsible for the failure of chemotherapy. The long non-coding RNA (lncRNA) metastasis-associated lung adenocarcinoma transcript (MALAT1) has been reported to be closely related to tumor biology. In the present study, whether MALAT1 contributes to the resistance of glioblastoma cell lines to temozolomide (TMZ) was investigated.
METHODS: The glioblastoma cell lines U251 and U87 were exposed to increasing concentrations of TMZ to generate TMZ-resistant colonies (the U251/TMZ and U87/TMZ cell lines). The expression levels of MALAT1 and proteins related to epithelial-mesenchymal transition (EMT) were detected by real-time PCR and western blot, respectively. After the transfection of si-MALAT1 or pcDNA-MALAT1, cell viability, mRNA expression of MDR-associated proteins (MDR1, MRP5 and LRP1), and protein expression of EMT related proteins (ZEB1, Snail and SLUG) were evaluated.
RESULTS: The expression of MALAT1 was upregulated in the U251/TMZ and U87/TMZ cell lines compared to that in U251 and U87 cell lines, respectively. The treatment of si-MALAT1 decreased MDR1, MRP5, and LRP1 expression, enhanced cell sensitivity to TMZ, and downregulated ZEB1 protein expression, whereas pcDNA-MALAT1 had the opposite effects. However, the effects of si-MALAT1 on MDR -associated protein expression, cell viability, and EMT status were reversed by the transfection of pcDNA-ZEB1, and the effects of pcDNA-MALAT1 were reversed by the transfection of si-ZEB1. In vivo, MALAT1 overexpression enhanced tumors' TMZ resistance and upregulated ZEB1 expression.
CONCLUSION: MALAT1 decreased the sensitivity of resistant glioma cell lines to TMZ by regulating ZEB1.
De Santi C, Pucci P, Bonotti A, et al.Mesothelin promoter variants are associated with increased soluble mesothelin-related peptide levels in asbestos-exposed individuals.
Occup Environ Med. 2017; 74(6):456-463 [PubMed
] Related Publications
BACKGROUND: Soluble mesothelin-related peptide (SMRP) is a promising diagnostic biomarker for malignant pleural mesothelioma (MPM), but various confounders hinder its usefulness in surveillance programmes. We previously showed that a single nucleotide polymorphism (SNP) within the 3'untranslated region (3'UTR) of the
OBJECTIVES: To focus on SNPs located within
METHODS: The association between SMRP and SNPs was tested in 689 non-MPM subjects and 70 patients with MPM. Reporter plasmids carrying the four most common haplotypes were compared in a dual luciferase assay, and in silico analyses were performed to investigate the putative biological role of the SNPs.
RESULTS: We found a strong association between serum SMRP and variant alleles of rs3764247, rs3764246 (in strong linkage disequilibrium with rs2235504) and rs2235503 in non-MPM subjects. Inclusion of the genotype information led to an increase in SMRP specificity from 79.9% to 85.5%. Although not statistically significant, the group with MPM showed the same trend of association. According to the in vitro luciferase study, rs3764247 itself had a functional role. In silico approaches showed that the binding sites for transcription factors such as Staf and ZNF143 could be affected by this SNP. The other SNPs were shown to interact with each other in a more complex way.
CONCLUSIONS: These data support the suggestion that SMRP performance is affected by individual (ie, genetic) variables and that
Battolla E, Canessa PA, Ferro P, et al.Comparison of the Diagnostic Performance of Fibulin-3 and Mesothelin in Patients with Pleural Effusions from Malignant Mesothelioma.
Anticancer Res. 2017; 37(3):1387-1391 [PubMed
] Related Publications
BACKGROUND: In the literature, there exist conflicting data on the value of fibulin-3 (FBLN3) for the diagnosis of pleural effusion (PE) in malignant pleural mesothelioma (MPM). Therefore we compared the diagnostic performance of FBLN3 against that of soluble mesothelin-related peptide (SMRP) in a cohort of Italian patients.
MATERIALS AND METHODS: FBLN3 and SMRP were detected in PE from 33 patients with MPM, 64 with pleural benign lesions and 23 with non-MPM pleural metastases using a commercial enzyme-linked-immunosorbent(ELISA)-assay kit according to manufacturers' instructions.
RESULTS: Levels of FBLN3 were similar in PE from MPM and PE from other pathologies (geometric mean=68.1 vs. 66.2 ng/ml; p=0.872) in contrast to SMRP levels, which were significantly higher in PE from MPM (geometric mean=14.6 vs. 3.2 nM; p<0.001). Receiver operating characteristic analysis confirmed that SMRP showed a good performance (area under the curve=0.79, p<0.001), whereas FBLN3 was not able to discriminate MPM from other pathologies (area under the curve=0.44, p=0.838).
CONCLUSION: FBLN3 detection in PE, in contrast to SMRP detection, is not useful as a biomarker for the diagnosis of PE from MPM.
Paclitaxel is clinically used as a first-line chemotherapeutic regimen for several cancer types, including head and neck cancers. However, acquired drug resistance results in the failure of therapy, metastasis and relapse. The drug efflux mediated by ATP-binding cassette (ABC) transporters and the survival signals activated by forkhead box (FOX) molecules are critical in the development of paclitaxel drug resistance. Whether FOX molecules promote paclitaxel resistance through drug efflux remains unknown. In this study, we developed several types of paclitaxel-resistant (TR) nasopharyngeal carcinoma (NPC) cells. These TR NPC cells acquired cancer stem cell (CSC) phenotypes and underwent epithelial to mesenchymal transition (EMT), and developed multidrug resistance. TR cells exhibited stronger drug efflux than parental NPC cells, leading to the reduction of intracellular drug concentrations and drug insensitivity. After screening the gene expression of ABC transporters and FOX molecules, we found that FOXM1 and ABCC5 were consistently overexpressed in the TR NPC cells and in patient tumor tissues. Further studies demonstrated that FOXM1 regulated abcc5 gene transcription by binding to the FHK consensus motifs at the promoter. The depletion of FOXM1 or ABCC5 with siRNA significantly blocked drug efflux and increased the intracellular concentrations of paclitaxel, thereby promoting paclitaxel-induced cell death. Siomycin A, a FOXM1 inhibitor, significantly enhanced in vitro cell killing by paclitaxel in drug-resistant NPC cells. This study is the first to identify the roles of FOXM1 in drug efflux and paclitaxel resistance by regulating the gene transcription of abcc5, one of the ABC transporters. Small molecular inhibitors of FOXM1 or ABCC5 have the potential to overcome paclitaxel chemoresistance in NPC patients.
Amponsah PS, Fan P, Bauer N, et al.microRNA-210 overexpression inhibits tumor growth and potentially reverses gemcitabine resistance in pancreatic cancer.
Cancer Lett. 2017; 388:107-117 [PubMed
] Related Publications
Resistance to first-line chemotherapies like gemcitabine contributes to high disease lethality in pancreatic cancer. By microarray and qRT-PCR, we observed significant downregulation of microRNA-210 in gemcitabine-resistant cells. The overexpression of microRNA-210 was toxic to gemcitabine-resistant cells and enhanced gemcitabine sensitivity. MicroRNA-210 overexpression induced caspase-3-mediated apoptosis, and inhibited colony formation. Computationally, ABCC5, a highly expressed gene in our array data, was identified as a potential target of microRNA-210 and the overexpression of ABCC5 in gemcitabine-resistant cells was confirmed by qRT-PCR. MicroRNA-210 overexpression reduced ABCC5 mRNA levels and inhibited a luciferase reporter expressing the ABCC5 3' UTR. The expression pattern of microRNA-210 and ABCC5 was mirrored in all of 5 pancreatic cancer cell lines used. Likewise, microRNA-210 transfection nearly totally inhibited tumor xenograft growth, proliferation and metastasis without obvious side effects in vivo. Also, an absence or low expression of microRNA-210 correlated to high ABCC5 expression in the majority of malignant patient tissues from a total of 101 patient tissues examined. Our observations provide at first glance, an important function for microRNA-210 in regulation of gemcitabine responsiveness by it's target gene ABCC5.
AIM: Metabolism and transport play major roles in life-long exposure to endogenous and exogenous carcinogens. We therefore explored associations between polymorphisms in absorption, distribution, metabolism and elimination genes and the risk and prognosis of castration-resistant prostate cancer (CRPC).
MATERIALS & METHODS: A total of 634 genotypes were tested in 74 patients using the Affymetrix DMETv1.0 platform.
RESULTS: No relation to risk was found. Three SNPs were associated with CRPC prognosis in Caucasians: ABCB11 rs7602171G>A (p = 0.003; n = 30; hazard ratio [HR]: 0.307), GSTP1 rs1799811C>T (p = 0.001; n = 38; HR: 0.254) and SLC5A6 rs1395 (p = 0.004; n = 35; HR: 3.15). Two other polymorphisms among Caucasians were associated with interesting trends: ABCB4 rs2302387C>T (p = 0.039) and ABCC5 rs939339A>G (p = 0.018).
CONCLUSION: This exploratory study is the first to show that polymorphisms in several absorption, distribution, metabolism and elimination genes may be associated with CRPC prognosis.
Kadioglu O, Cao J, Kosyakova N, et al.Genomic and transcriptomic profiling of resistant CEM/ADR-5000 and sensitive CCRF-CEM leukaemia cells for unravelling the full complexity of multi-factorial multidrug resistance.
Sci Rep. 2016; 6:36754 [PubMed
] Free Access to Full Article Related Publications
We systematically characterised multifactorial multidrug resistance (MDR) in CEM/ADR5000 cells, a doxorubicin-resistant sub-line derived from drug-sensitive, parental CCRF-CEM cells developed in vitro. RNA sequencing and network analyses (Ingenuity Pathway Analysis) were performed. Chromosomal aberrations were identified by array-comparative genomic hybridisation (aCGH) and multicolour fluorescence in situ hybridisation (mFISH). Fifteen ATP-binding cassette transporters and numerous new genes were overexpressed in CEM/ADR5000 cells. The basic karyotype in CCRF-CEM cells consisted of 47, XX, der(5)t(5;14) (q35.33;q32.3), del(9) (p14.1), +20. CEM/ADR5000 cells acquired additional aberrations, including X-chromosome loss, 4q and 14q deletion, chromosome 7 inversion, balanced and unbalanced two and three way translocations: t(3;10), der(3)t(3;13), der(5)t(18;5;14), t(10;16), der(18)t(7;18), der(18)t(21;18;5), der(21;21;18;5) and der(22)t(9;22). CCRF-CEM consisted of two and CEM/ADR5000 of five major sub-clones, indicating genetic tumor heterogeneity. Loss of 3q27.1 in CEM/ADR5000 caused down-regulation of ABCC5 and ABCF3 expression, Xq28 loss down-regulated ABCD1 expression. ABCB1, the most well-known MDR gene, was 448-fold up-regulated due to 7q21.12 amplification. In addition to well-known drug resistance genes, numerous novel genes and genomic aberrations were identified. Transcriptomics and genetics in CEM/AD5000 cells unravelled a range of MDR mechanisms, which is much more complex than estimated thus far. This may have important implications for future treatment strategies.
BACKGROUND: Oesophageal adenocarcinoma represents one of the fastest rising cancers in high-income countries. Barrett's oesophagus is the premalignant precursor of oesophageal adenocarcinoma. However, only a few patients with Barrett's oesophagus develop adenocarcinoma, which complicates clinical management in the absence of valid predictors. Within an international consortium investigating the genetics of Barrett's oesophagus and oesophageal adenocarcinoma, we aimed to identify novel genetic risk variants for the development of Barrett's oesophagus and oesophageal adenocarcinoma.
METHODS: We did a meta-analysis of all genome-wide association studies of Barrett's oesophagus and oesophageal adenocarcinoma available in PubMed up to Feb 29, 2016; all patients were of European ancestry and disease was confirmed histopathologically. All participants were from four separate studies within Europe, North America, and Australia and were genotyped on high-density single nucleotide polymorphism (SNP) arrays. Meta-analysis was done with a fixed-effects inverse variance-weighting approach and with a standard genome-wide significance threshold (p<5 × 10
FINDINGS: Our sample comprised 6167 patients with Barrett's oesophagus and 4112 individuals with oesophageal adenocarcinoma, in addition to 17 159 representative controls from four genome-wide association studies in Europe, North America, and Australia. We identified eight new risk loci associated with either Barrett's oesophagus or oesophageal adenocarcinoma, within or near the genes CFTR (rs17451754; p=4·8 × 10
INTERPRETATION: Our meta-analysis of genome-wide association studies doubled the number of known risk loci for Barrett's oesophagus and oesophageal adenocarcinoma and revealed new insights into causes of these diseases. Furthermore, the specific association between oesophageal adenocarcinoma and the locus near HTR3C and ABCC5 might constitute a novel genetic marker for prediction of the transition from Barrett's oesophagus to oesophageal adenocarcinoma. Fine-mapping and functional studies of new risk loci could lead to identification of key molecules in the development of Barrett's oesophagus and oesophageal adenocarcinoma, which might encourage development of advanced prevention and intervention strategies.
FUNDING: US National Cancer Institute, US National Institutes of Health, National Health and Medical Research Council of Australia, Swedish Cancer Society, Medical Research Council UK, Cambridge NIHR Biomedical Research Centre, Cambridge Experimental Cancer Medicine Centre, Else Kröner Fresenius Stiftung, Wellcome Trust, Cancer Research UK, AstraZeneca UK, University Hospitals of Leicester, University of Oxford, Australian Research Council.
Runt-related transcription factor 3 (RUNX3) is known to function as a tumor suppressor in gastric cancer and other types of cancers, including hepatocellular carcinoma (HCC). However, its role has not been fully elucidated. In the present study, we aimed to evaluate the role of RUNX3 in HCC. We used the human HCC cell lines Hep3B, Huh7 and HLF; RUNX3 cDNA was introduced into Hep3B and Huh7 cells, which were negative for endogenous RUNX3 expression, and RUNX3 siRNA was transfected into HLF cells, which were positive for endogenous RUNX3. We analyzed the expression of RUNX3 and multidrug resistance-associated protein (MRP) by immunoblotting. MTT assays were used to determine the effects of RUNX3 expression on 5-fluorouracil (5-FU) and cisplatin (CDDP) sensitivity. Finally, 23 HCC specimens resected from patients with HCC at Okayama University Hospital were analyzed, and correlations among immunohistochemical expression of RUNX3 protein and MRP protein were evaluated in these specimens. Exogenous RUNX3 expression reduced the expression of MRP1, MRP2, MRP3 and MRP5 in the RUNX3-negative cells, whereas knockdown of RUNX3 in the HLF cells stimulated the expression of these MRPs. An inverse correlation between RUNX3 and MRP expression was observed in the HCC tissues. Importantly, loss of RUNX3 expression contributed to 5-FU and CDDP resistance by inducing MRP expression. These data have important implications in the study of chemotherapy resistance in HCC.
Lal S, Sutiman N, Ooi LL, et al.Pharmacogenetics of ABCB5, ABCC5 and RLIP76 and doxorubicin pharmacokinetics in Asian breast cancer patients.
Pharmacogenomics J. 2017; 17(4):337-343 [PubMed
] Related Publications
This study investigated the impact of ABCB5, ABCC5 and RLIP76 polymorphisms on doxorubicin pharmacokinetics in Asian breast cancer patients (N=62). Direct sequencing was performed to screen for previously identified ABCC5 polymorphisms as well as polymorphisms in the exons and exon-intron boundaries of ABCB5 and RLIP76 genes. Genotype-phenotype correlations were analyzed using Mann-Whitney U-test. The homozygous variant allele at the ABCC5 g.+7161G>A (rs1533682) locus was significantly associated with higher doxorubicin clearance (g.+7161AA vs g.+7161GG, CL/BSA (Lh
Litviakov NV, Cherdyntseva NV, Tsyganov MM, et al.Deletions of multidrug resistance gene loci in breast cancer leads to the down-regulation of its expression and predict tumor response to neoadjuvant chemotherapy.
Oncotarget. 2016; 7(7):7829-41 [PubMed
] Free Access to Full Article Related Publications
Neoadjuvant chemotherapy (NAC) is intensively used for the treatment of primary breast cancer. In our previous studies, we reported that clinical tumor response to NAC is associated with the change of multidrug resistance (MDR) gene expression in tumors after chemotherapy. In this study we performed a combined analysis of MDR gene locus deletions in tumor DNA, MDR gene expression and clinical response to NAC in 73 BC patients. Copy number variations (CNVs) in biopsy specimens were tested using high-density microarray platform CytoScanTM HD Array (Affymetrix, USA). 75%-100% persons having deletions of MDR gene loci demonstrated the down-regulation of MDR gene expression. Expression of MDR genes was 2-8 times lower in patients with deletion than in patients having no deletion only in post-NAC tumors samples but not in tumor tissue before chemotherapy. All patients with deletions of ABCB1 ABCB 3 ABCC5 gene loci--7q21.1, 6p21.32, 3q27 correspondingly, and most patients having deletions in ABCC1 (16p13.1), ABCC2 (10q24), ABCG1 (21q22.3), ABCG2 (4q22.1), responded favorably to NAC. The analysis of all CNVs, including both amplification and deletion showed that the frequency of 13q14.2 deletion was 85% among patients bearing tumor with the deletion at least in one MDR gene locus versus 9% in patients with no deletions. Differences in the frequency of 13q14.2 deletions between the two groups were statistically significant (p = 2.03 × 10(-11), Fisher test, Bonferroni-adjusted p = 1.73 × 10(-8)). In conclusion, our study for the first time demonstrates that deletion MDR gene loci can be used as predictive marker for tumor response to NAC.
Shinozuka K, Tang H, Jones RB, et al.Impact of Polymorphic Variations of Gemcitabine Metabolism, DNA Damage Repair, and Drug-Resistance Genes on the Effect of High-Dose Chemotherapy for Relapsed or Refractory Lymphoid Malignancies.
Biol Blood Marrow Transplant. 2016; 22(5):843-9 [PubMed
] Free Access to Full Article Related Publications
The goal of this study was to determine whether single nucleotide polymorphisms (SNPs) in genes involved in gemcitabine metabolism, DNA damage repair, multidrug resistance, and alkylator detoxification influence the clinical outcome of patients with refractory/relapsed lymphoid malignancies receiving high-dose gemcitabine/busulfan/melphalan (Gem/Bu/Mel) with autologous stem cell support. We evaluated 21 germline SNPs of the gemcitabine metabolism genes CDA, deoxycytidine kinase, and hCNT3; DNA damage repair genes RECQL, X-ray repair complementing 1, RAD54L, ATM, ATR, MLH1, MSH2, MSH3, TREX1, EXO1, and TP73; and multidrug-resistance genes MRP2 and MRP5; as well as glutathione-S-transferase GSTP1 in 153 patients with relapsed or refractory lymphoma or myeloma receiving Gem/Bu/Mel. We studied the association of genotypes with overall survival (OS), progression-free survival (PFS), and nonhematological grade 3 or 4 toxicity. CDA C111T and TREX1 Ex14-460C>T genotypes had a significant effect on OS (P = .007 and P = .005, respectively), and CDA C111T, ATR C340T, and EXO1 P757L genotypes were significant predictors for severe toxicity (P = .037, P = .024, and P = .025, respectively) in multivariable models that adjusted for clinical variables. The multi-SNP risk score analysis identified the combined genotypes of TREX1 Ex14-460 TT and hCNT3 Ex5 +25A>G AA as significant predictors for OS and the combination of MRP2 Ex10 + 40GG/GA and MLH1 IVS12-169 TT as significant predictor for PFS. Polymorphic variants of certain genes involved in gemcitabine metabolism and DNA damage repair pathways may be potential biomarkers for clinical outcome in patients with refractory/relapsed lymphoid tumors receiving Gem/Bu/Mel.
Karatas OF, Guzel E, Duz MB, et al.The role of ATP-binding cassette transporter genes in the progression of prostate cancer.
Prostate. 2016; 76(5):434-44 [PubMed
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BACKGROUND: Prostate cancer (PCa) is the most commonly diagnosed neoplasm and the second leading cause of cancer-related death among men in developed countries. There is no clear evidence showing the success of current screening tests in reducing mortality of PCa. In this study, we aimed to profile expressions of nine ABC transporters, ABCA5, ABCB1, ABCB6, ABCC1, ABCC2, ABCC3, ABCC5, ABCC10, and ABCF2, in recurrent, non-recurrent PCa and normal prostate tissues.
METHODS: A total of 77 (39 recurrent, 38 non-recurrent) radical prostatectomy and 20 normal prostate samples, obtained from Baylor College of Medicine Prostate Cancer program, were included into the study and divided into two independent groups as test and validation sample sets. Differential expression of selected ABC transporters was assessed using quantitative real-time PCR (qRT-PCR). Pearson's correlation test, receiver operating characteristics (ROC) analysis and Kaplan-Meier test were used for statistical analysis.
RESULTS: QRT-PCR results demonstrated the elevated expression of ABCA5, ABCB1, ABCB6, ABCC1, and ABCC2 as well as reduced expression of ABCC3 in PCa samples compared to normal prostate tissues. In addition, we found deregulation of ABCB1, ABCB6, ABCC3, and ABCC10 in recurrent PCa samples and validated differential expression of ABCB6, ABCC3, and ABCC10 in recurrent PCa compared to non-recurrent PCa. Pearson's correlation, ROC and Kaplan-Meier analysis revealed the power of these three ABC transporters for estimating prognosis of PCa.
CONCLUSIONS: We demonstrated differential expression of ABC transporters both in tumor versus normal and recurrent versus non-recurrent comparisons. Our data suggest ABCB6, ABCC3, and ABCC10 as valuable predictors of PCa progression.
Ge G, Zhou C, Ren Y, et al.Enhanced SLC34A2 in breast cancer stem cell-like cells induces chemotherapeutic resistance to doxorubicin via SLC34A2-Bmi1-ABCC5 signaling.
Tumour Biol. 2016; 37(4):5049-62 [PubMed
] Related Publications
Even though early detection methods and treatment options are greatly improved, chemoresistance is still a tremendous challenge for breast cancer therapy. Breast cancer stem cells (BCSCs) represent a subpopulation that is central to chemoresistance. We aim to investigate the relationship between SLC34A2 and chemoresistance in BCSCs and identify the underlying mechanisms by which SLC34A2 regulates chemoresistance in BCSCs. Fluorescence Activated Cell Sorting (FACS) analysis showed the presence of a variable fraction of CD44(+)CD24(-) cells in 25 out of 25 breast cancer samples. We cultured primary breast cancer sample cells and breast cancer cell line cells to induce sphere formation in serum-free medium. Following sorting of CD44(+)CD24(-) cells from spheres, we showed that CD44(+)CD24(-) cells displayed stem cell-like features and were resistant to chemotherapy drug doxorubicin. Significantly, enhanced SLC34A2 expression correlated with chemoresponse and survival of breast cancer patients. We subsequently indicated that increased SLC34A2 expression in BCSCs directly contributed to their chemoresistance by a series of in vitro and in vivo experiments. Furthermore, we demonstrated that SLC34A2 induced chemoresistance in BCSCs via SLC34A2-Bmi1-ABCC5 signaling. Finally, we showed that ABCC5 was a direct transcriptional target of Bmi1 by chromatin immunoprecipitation (ChIP). In conclusion, our work indicated that decreased SLC34A2 expression sensitized BCSCs to doxorubicin via SLC34A2-Bmi1-ABCC5 signaling and shed new light on understanding the mechanism of chemoresistance in BCSCs. This study not only bridges the missing link between stem cell-related transcription factor (Bmi1) and ABC transporter (ABCC5) but also contributes to development of potential therapeutics against breast cancer.
Santarelli L, Staffolani S, Strafella E, et al.Combined circulating epigenetic markers to improve mesothelin performance in the diagnosis of malignant mesothelioma.
Lung Cancer. 2015; 90(3):457-64 [PubMed
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OBJECTIVES: Malignant mesothelioma (MM) is a highly aggressive tumor with poor prognosis. A major challenge is the development and application of early and highly reliable diagnostic marker(s). Serum biomarkers, such as 'soluble mesothelin-related proteins' (SMRPs), is the most studied and frequently used in MM. However, the low sensitivity of SMRPs for early MM limits its value; therefore, additional biomarkers are required. In this study, two epigenetically regulated markers in MM (microRNA-126, miR-126, and methylated thrombomodulin promoter, Met-TM) were combined with SMRPs and evaluated as a potential strategy to detect MM at an early stage.
MATERIALS AND METHODS: A total of 188 subjects, including 45 MM patients, 99 asbestos-exposed subjects, and 44 healthy controls were prospectively enrolled, serum samples collected, and serum levels of SMRPs, miR-126 and Met-TM evaluated. Logistic regression analysis was performed to evaluate the diagnostic value of the three biomarkers. Using this approach, the performance of the '3-biomarker classifier' was tested by calculating the overall probability score of the MM and control samples, respectively, and the ROC curve was generated.
RESULTS AND CONCLUSION: The combination of the three biomarkers was the best predictor to differentiate MM patients from asbestos-exposed subjects and healthy controls. The accuracy and cancer specificity was confirmed in a second validation cohort and lung cancer population. We propose that the combination of the two epigenetic biomarkers with SMRPs as a diagnosis for early MM overcomes the limitations of using SMRPs alone.
Zaruma-Torres F, Lares-Asseff I, Reyes-Espinoza A, et al.Association of ABCB1, ABCC5 and xanthine oxidase genetic polymorphisms with methotrexate adverse reactions in Mexican pediatric patients with ALL.
Drug Metab Pers Ther. 2015; 30(3):195-201 [PubMed
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BACKGROUND: Acute lymphoblastic leukemia (ALL) is one of the most frequent oncological disorders in pediatric populations. To date, the drug of choice for the treatment of ALL is methotrexate, a drug associated with a high risk of adverse reactions (ADRs). The xanthine oxidase (XO) polymorphisms, 1936A>G and 2107A>G, as well as the polymorphic variants derived from ATP-binding cassette transporter gene subfamilies, ABCB1 and ABCC5, of drug resistant codifying genes, are implicated as precursors of drug-related neurologic, hepatic, and renal toxicities. Our aim was to determine whether the mentioned polymorphisms are risk or protective factors for the development of adverse reactions by methotrexate in our pediatric population with ALL.
METHODS: A total of 35 Mexican children from Centro Estatal de Cancerología-Durango, Mexico, with ALL and the previously noted polymorphisms as determined qPCR were studied. At the same time, a 12-month drug monitoring program was conducted in accordance with WHO-PAHO guidelines for pharmacovigilance.
RESULTS: The ABCB11936A>G and 2107A>G and ABCC5 3414+434A>C polymorphisms were not associated with methotrexate ADRs. Single nucleotide polymorphisms (SNPs) of ABCB1 1236C>T (OR 0.19, 95% CI: 0.03-0.9, p<0.05) and ABCC5 3933+313T>C (OR 0.12, 95% CI: 0.027-0.58, p<0.05) were associated with methotrexate ADRs.
CONCLUSIONS: SNPs 1236C>T of ABCB1 and ABCC5 3933+313T>C are not associated with the development of typical ADRs by methotrexate, rather, they showed a protective factor for myelosuppression in the studied sick population.
Chen S, Villeneuve L, Jonker D, et al.ABCC5 and ABCG1 polymorphisms predict irinotecan-induced severe toxicity in metastatic colorectal cancer patients.
Pharmacogenet Genomics. 2015; 25(12):573-83 [PubMed
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OBJECTIVE: Irinotecan is a cytotoxic agent used widely for the treatment of solid tumors, particularly for metastatic colorectal cancers. Treatment with this drug frequently results in severe neutropenia and diarrhea that can markedly impact the course of treatment and patients' quality of life. Pharmacogenomic tailoring of irinotecan-based chemotherapy has been the subject of several investigations, but with limited data on ATP-binding cassette (ABC) and solute carrier (SLC) transporter genes.
MATERIALS AND METHODS: In this study, we aimed to discover toxicity-associated markers in seven transporter genes participating in irinotecan pharmacokinetics involving the ABC transporter genes ABCB1, ABCC1, ABCC2, ABCC5, ABCG1, and ABCG2 and the solute carrier organic anion transporter gene SLCO1B1 and using a haplotype-tagging single-nucleotide polymorphisms (n=210 htSNPs) strategy. The profiles of 167 metastatic colorectal cancer Canadian patients treated with FOLFIRI-based regimens were examined and the findings were replicated in an independent cohort of 250 Italian patients.
RESULTS: In combined cohorts, a two-marker ABCC5 rs3749438 and rs10937158 haplotype (T-C) predicted lower risk of severe diarrhea [odds ratio (OR) of 0.43; P=0.001]. The co-occurrence of ABCG1 rs225440T and ABCC5 rs2292997A predicted the risk of severe neutropenia (OR=5.93; P=0.0002), which was further improved when incorporating the well-known risk marker UGT1A1*28 rs8175347 (OR=7.68; P<0.0001). In contrast, carriers of one protective marker (UGT1 rs11563250G) but none of these risk alleles experienced significantly less severe neutropenia (8.2 vs. 34.0%; P<0.0001).
CONCLUSION: This combination of predictive genetic markers could potentially lead to better risk assessment and may thus improve personalized treatment.
Krajinovic M, Elbared J, Drouin S, et al.Polymorphisms of ABCC5 and NOS3 genes influence doxorubicin cardiotoxicity in survivors of childhood acute lymphoblastic leukemia.
Pharmacogenomics J. 2016; 16(6):530-535 [PubMed
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Anthracyclines are efficient chemotherapy agents. However, their use is limited by anthracycline-induced cardiotoxicity (CT). We investigated the influence of polymorphisms in doxorubicin metabolic and functional pathways on late-onset CT as estimated by echocardiography in 251 childhood acute lymphoblastic leukemia (cALL) patients. Association analyses revealed a modulating effect of two variants: A-1629 T in ABCC5, an ATP-binding cassette transporter, and G894T in the NOS3 endothelial nitric oxide synthase gene. Individuals with the ABCC5 TT-1629 genotype had an average of 8-12% reduction of ejection (EF) and shortening fractions (SF; EF: P<0.0001, and SF: P=0.001, respectively). A protective effect of the NOS3 TT894 genotype on EF was seen in high-risk patients (P=0.02), especially in those who did not receive dexrazoxane (P=0.002). Analysis of an additional cohort of 44 cALL patients replicated the ABCC5 association but was underpowered for NOS3. In summary, we identified two biomarkers that may contribute to cALL anthracycline CT risk stratification.
Hagleitner MM, Coenen MJ, Gelderblom H, et al.A First Step toward Personalized Medicine in Osteosarcoma: Pharmacogenetics as Predictive Marker of Outcome after Chemotherapy-Based Treatment.
Clin Cancer Res. 2015; 21(15):3436-41 [PubMed
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PURPOSE: Overall survival in patients with osteosarcoma is only 60%. Poor response to chemotherapy is the dominant risk factor for poor survival. Pharmacogenetic research can offer possibilities to optimize treatment and improve outcome. We applied a pathway-based approach to evaluate the cumulative effect of genes involved in the metabolism of cisplatin and doxorubicin in relationship to clinical outcome.
EXPERIMENTAL DESIGN: We included 126 patients with osteosarcoma. To comprehensively assess common genetic variation in the 54 genes selected, linkage disequilibrium (LD; r(2) = 0.8)-based tag-single nucleotide polymorphisms (SNP) strategy was used. A final set of 384 SNPs was typed using Illumina Beadarray platform. SNPs significantly associated with 5-year progression-free survival (PFS) were replicated in another 64 patients with osteosarcoma.
RESULTS: We identified five variants in FasL, MSH2, ABCC5, CASP3, and CYP3A4 that were associated with 5-year PFS. Risk stratification based on the combined effects of the risk alleles showed a significant improvement of 5-year PFS. Patients that carried no or only one risk allele had a 5-year PFS of 100% compared with a 5-year PFS of 84.4% for carriers of two or three risk alleles, 66.7% PFS if a patient carried four to five alleles, and a 5-year PFS of 41.8% for patients with >5 risk alleles (P < 0.001).
CONCLUSIONS: We identified several genes that showed association with PFS in patients with osteosarcoma. These pharmacogenetic risk factors might be useful to predict treatment outcome and to stratify patients immediately after diagnosis and offer the possibility to improve treatment and outcome.
MicroRNA-381 (miR-381) is a highly expressed onco-miRNA that is involved in malignant progression and has been suggested to be a good target for glioblastoma multiforme (GBM) therapy. In this study, we employed two-dimensional fluorescence differential gel electrophoresis (2-D DIGE) and MALDI-TOF/TOF-MS/MS to identify 27 differentially expressed proteins, including the significantly upregulated neurofilament light polypeptide (NEFL), in glioblastoma cells in which miR-381 expression was inhibited. We identified NEFL as a novel target molecule of miR-381 and a tumor suppressor gene. In human astrocytoma clinical specimens, NEFL was downregulated with increased levels of miR-381 expression. Either suppressing miR-381 or enforcing NEFL expression dramatically sensitized glioblastoma cells to temozolomide (TMZ), a promising chemotherapeutic agent for treating GBMs. The mechanism by which these cells were sensitized to TMZ was investigated by inhibiting various multidrug resistance factors (ABCG2, ABCC3, and ABCC5) and stemness factors (ALDH1, CD44, CKIT, KLF4, Nanog, Nestin, and SOX2). Our results further demonstrated that miR-381 overexpression reversed the viability of U251 cells exhibiting NEFL-mediated TMZ sensitivity. In addition, NEFL-siRNA also reversed the proliferation rate of U251 cells exhibiting locked nucleic acid (LNA)-anti-miR-381-mediated TMZ sensitivity. Overall, the miR-381-NEFL axis is important for TMZ resistance in GBM and may potentially serve as a novel therapeutic target for glioma.
Kohan HG, Boroujerdi MTime and concentration dependency of P-gp, MRP1 and MRP5 induction in response to gemcitabine uptake in Capan-2 pancreatic cancer cells.
Xenobiotica. 2015; 45(7):642-52 [PubMed
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1. Influx and efflux proteins play a major role in the overall uptake and efficacy of chemotherapeutic agents and cellular chemo-resistance. 2. The present study investigated the time course and dose dependency of the induction of three efflux proteins, P-gp, MRP1 and MRP5, in response to gemcitabine exposure in Capan-2 pancreatic cancer cell line at transcriptional and translational levels. The influence of exposure on the influx protein (ENT1), the net cellular uptake of the gemcitabine, the overall ATPase activity and the cell death rate were also measured. 3. The time course of the expression exhibited an initial rise, toward a plateau level. The estimated Km and Vmax confirmed that MRP5 and to a lesser extent MRP1 are the prominent proteins for efflux of gemcitabine. Both mRNA and protein expression demonstrated the time and concentration dependency of the induction; and the elevated ATPase activity validated that the induced efflux proteins are functionally active. 4. The results of the study revealed that the efficacy window of gemcitabine as it relates to the function of the efflux proteins is concentration and temporal dependent and is well correlated to the first 60 min of exposure.
Overexpression and/or activation of HER2 confers resistance of cancer cells to chemotherapeutic drugs. NRF2 also gives drug resistance of cancer cells through induction of detoxification and/or drug efflux proteins. Although several upstream effectors of NRF2 overlapped with the downstream molecules of HER2 pathway, no direct link between HER2 and NRF2 has ever been established. Here, we identified that co-expression of a constitutively active HER2 (HER2CA) and NRF2 increased the levels of NRF2 target proteins, HO-1 and MRP5. We also identified HER2CA activated the DNA-binding of NRF2 and the antioxidant response element (ARE)-mediated transcription in an NRF2-dependent manner. In addition, NRF2 and HER2CA cooperatively up-regulated the mRNA expression of various drug-resistant and detoxifying enzymes including GSTA2, GSTP1, CYP3A4, HO-1, MRP1, and MRP5. We also demonstrated that NRF2 binds to HER2 not only in transiently transfected HEK293T cells but also in HER2-amplified breast cancer cells. Functionally, overexpression of HER2CA gave resistance of MCF7 breast cancer cells to either paraquat or doxorubicin. Overexpression of dominant negative NRF2 (DN-NRF2) reduced the HER2CA-induced resistance of MCF7 cells to these agents. Taken together, these results suggest that active HER2 binds and regulates the NRF2-dependent transcriptional activation and induces drug resistance of cancer cells.
Garritano S, De Santi C, Silvestri R, et al.A common polymorphism within MSLN affects miR-611 binding site and soluble mesothelin levels in healthy people.
J Thorac Oncol. 2014; 9(11):1662-8 [PubMed
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INTRODUCTION: Soluble mesothelin related peptide (SMRP) was proposed as a promising diagnostic marker for malignant pleural mesothelioma (MPM). In a previous study, we found that rs1057147 within the 3' untranslated region of MSLN gene was associated with SMRP levels. Thus, we aimed to (1) confirm the previous association on a large series of volunteers and (2) test the hypothesis that the SNP could affect microRNA binding sites.
METHODS: The association analysis was verified in 759 subjects. Then, in silico predictions highlighted miR-611 and miR-887 as candidate miRNAs binding to the polymorphic site. Thus, chimeric constructs bearing the alternative alleles (G > A) were assayed alone or in cotransfection with the miRNA mimics, with dual luciferase reporter assay in non-MPM Met-5A cells. The miRNAs were also assayed by western blot analysis for their ability to down-regulate endogenous mesothelin in the MPM Mero-14 cell line.
RESULTS: We confirmed that, among non-MPM volunteers, GG homozygotes have the lowest SMRP levels. When the genotype is taken into account, the specificity of SMRP as biomarker improves from 79.7% to 85.3%. Dual-luciferase assays showed a significantly lower reporter activity when the vector harbored the G allele as compared to A allele. miR-887 mimic caused a reduced reporter activity of vectors harboring A or G alleles, while miR-611 was effective only on the vector harboring the G allele. Transfection of these miRNAs into Mero-14 cells significantly reduced endogenous MSLN protein.
CONCLUSION: SMRP performance as diagnostic biomarker improved by considering the genotype rs1057147. This polymorphism most likely affects a binding site for miR-611.
Mutations in genes encoding proteins involved in RNA splicing have been found to occur at relatively high frequencies in several tumour types including myelodysplastic syndromes, chronic lymphocytic leukaemia, uveal melanoma, and pancreatic cancer, and at lower frequencies in breast cancer. To investigate whether dysfunction in RNA splicing is implicated in the pathogenesis of breast cancer, we performed a re-analysis of published exome and whole genome sequencing data. This analysis revealed that mutations in spliceosomal component genes occurred in 5.6% of unselected breast cancers, including hotspot mutations in the SF3B1 gene, which were found in 1.8% of unselected breast cancers. SF3B1 mutations were significantly associated with ER-positive disease, AKT1 mutations, and distinct copy number alterations. Additional profiling of hotspot mutations in a panel of special histological subtypes of breast cancer showed that 16% and 6% of papillary and mucinous carcinomas of the breast harboured the SF3B1 K700E mutation. RNA sequencing identified differentially spliced events expressed in tumours with SF3B1 mutations including the protein coding genes TMEM14C, RPL31, DYNL11, UQCC, and ABCC5, and the long non-coding RNA CRNDE. Moreover, SF3B1 mutant cell lines were found to be sensitive to the SF3b complex inhibitor spliceostatin A and treatment resulted in perturbation of the splicing signature. Albeit rare, SF3B1 mutations result in alternative splicing events, and may constitute drivers and a novel therapeutic target in a subset of breast cancers.
Recent studies have reported that hyper-methylation in the promoter region of miRNAs could silence the expression of tumor suppressive miRNAs and might play significant roles in the process of tumor development. However, the potential mechanisms regarding how methylation of miRNA CpG Island could regulate cancer cell chemo-resistance have not yet been studied. Using microarray and BSP (Bisulfate Sequencing PCR) assays, we found that compared with the parent SGC7901/VCR cells, expression of miR-129-5p was restored in SGC7901/VCR gastric cancer multi-drug resistant cell line treated by de-methylation reagent (5-AZA-dC). Using gain or loss of function assays, we found the over-expressed miR-129-5p reduced the chemo-resistance of SGC7901/VCR and SGC7901/ADR cells, while down-regulation of miR-129-5p had an opposite effect. Furthermore, three members of multi-drug resistance (MDR) related ABC transporters (ABCB1, ABCC5 and ABCG1) were found to be direct targets of miR-129-5p using bioinformatics analysis and report gene assays. The present study indicated that hyper-methylation of miR-129-5p CpG island might play important roles in the development of gastric cancer chemo-resistance by targeting MDR related ABC transporters and might be used as a potential therapeutic target in preventing the chemo-resistance of gastric cancer.