Gene Summary

Gene:RARS1; arginyl-tRNA synthetase 1
Aliases: HLD9, RARS, ArgRS, DALRD1
Summary:Aminoacyl-tRNA synthetases catalyze the aminoacylation of tRNA by their cognate amino acid. Because of their central role in linking amino acids with nucleotide triplets contained in tRNAs, aminoacyl-tRNA synthetases are thought to be among the first proteins that appeared in evolution. Arginyl-tRNA synthetase belongs to the class-I aminoacyl-tRNA synthetase family. [provided by RefSeq, Jul 2008]
Databases:OMIM, HGNC, Ensembl, GeneCard, Gene
Protein:arginine--tRNA ligase, cytoplasmic
Source:NCBIAccessed: 01 September, 2019


What does this gene/protein do?
Show (14)
Pathways:What pathways are this gene/protein implicaed in?
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Cancer Overview

Research Indicators

Publications Per Year (1994-2019)
Graph generated 01 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.

  • Cancer Gene Expression Regulation
  • Myelodysplastic Syndromes
  • Adolescents
  • Anemia, Refractory
  • Messenger RNA
  • Vitamin D Response Element
  • Receptors, Retinoic Acid
  • Apoptosis
  • Neoplasm Proteins
  • Lung Cancer
  • Breast Cancer
  • Polymerase Chain Reaction
  • Chromosome 5
  • Transfection
  • Teratocarcinoma
  • Squamous Cell Carcinoma
  • Retinoids
  • Retinoic Acid
  • Zinc Fingers
  • Acute Myeloid Leukaemia
  • Transcription
  • Base Sequence
  • Leukemia, Promyelocytic, Acute
  • Transcription Factors
  • Biomarkers, Tumor
  • Antineoplastic Agents
  • Gene Expression
  • RARA
  • Up-Regulation
  • Nuclear Proteins
  • Cell Division
  • Signal Transduction
  • Neoplastic Cell Transformation
  • Molecular Sequence Data
  • Chromosome Aberrations
  • Cell Differentiation
  • Promoter Regions
  • Drug Resistance
  • Retinoid X Receptors
  • Translocation
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: RARS (cancer-related)

Zhong Q, Liu ZH, Lin ZR, et al.
Clin Cancer Res. 2018; 24(3):659-673 [PubMed] Free Access to Full Article Related Publications

Feng X, Matsuo K, Zhang T, et al.
MicroRNA Profiling and Target Genes Related to Metastasis of Salivary Adenoid Cystic Carcinoma.
Anticancer Res. 2017; 37(7):3473-3481 [PubMed] Related Publications
BACKGROUND/AIM: Perineural invasion and distant metastasis lead to a poor prognosis of adenoid cystic carcinoma and there is no effective therapy available. MicroRNAs (miRNAs) are small non-coding RNAs that regulate target gene expression, which can be biomarkers or therapeutic targets for certain cancer types. We aimed to identify miRNAs and their target genes possibly involved in metastasis of salivary gland adenoid cystic carcinoma (SACC).
MATERIALS AND METHODS: Using Nanostring nCounter analysis, we examined miRNA expression in two SACC cell lines: SACC-83 and SACC-LM, with low and high lung metastasis rates, respectively. We then verified the differentially expressed miRNAs with real-time polymerase chain reaction in the cell lines and in tumor samples from patients with SACC. miRNA target-gene expression was also analyzed.
RESULTS: SACC-83 showed higher gene expression of miR-130a, miR-342, and miR-205; SACC-LM showed higher gene expression of miR-99a and miR-155. In human tissue, miR-205 was highly expressed in the primary SACC, while miR-155 and miR-342 were highly expressed in recurrent SACC. Six predicted target genes of miRNA-155 and miR-99a linked to tumorigenesis were further analyzed and RNA expression of ubiquitin-like modifier activating enzyme 2 (UBA2) was higher in SACC than normal salivary gland tissue, and higher in primary compared to recurrent SACC (p<0.05). RNA expression of retinoic acid receptors (RARS) was higher in tissue from primary than recurrent SACC and normal salivary gland (p<0.05), but that in recurrent SACC was not significantly higher than normal salivary gland tissue. RNA expression of minichromosome maintenance 8 homologous recombination repair factor (MCM8) and 24-dehydrocholesterol reductase (DHCR24) was higher in primary SACC than normal salivary gland tissue (p<0.05).
CONCLUSION: miR-99a, miR-155, miR-130a, miR-342, and miR-205 may play a role in metastasis of SACC. MiR-155 may be involved in SACC metastasis through UBA2 pathways, and UBA2 may function as a biomarker/mediator of SACC metastasis.

Janik S, Nowak U, Łaszkiewicz A, et al.
Diverse Regulation of Vitamin D Receptor Gene Expression by 1,25-Dihydroxyvitamin D and ATRA in Murine and Human Blood Cells at Early Stages of Their Differentiation.
Int J Mol Sci. 2017; 18(6) [PubMed] Free Access to Full Article Related Publications
Vitamin D receptor (VDR) is present in multiple blood cells, and the hormonal form of vitamin D, 1,25-dihydroxyvitamin D (1,25D) is essential for the proper functioning of the immune system. The role of retinoic acid receptor α (RARα) in hematopoiesis is very important, as the fusion of RARα gene with PML gene initiates acute promyelocytic leukemia where differentiation of the myeloid lineage is blocked, followed by an uncontrolled proliferation of leukemic blasts. RARα takes part in regulation of

Perri M, Caroleo MC, Liu N, et al.
9-cis Retinoic acid modulates myotrophin expression and its miR in physiological and pathophysiological cell models.
Exp Cell Res. 2017; 354(1):25-30 [PubMed] Related Publications
Functional studies indicate that essential cellular processes are controlled by Vitamin A derivatives. Among these the retinoic acid isoforms, all-trans- and 9-cis (9cRA), regulate the expression of various genes in both physiological and pathological conditions. Using several in vitro experimental models such as pancreatic β-cells, pre-adipocytes and breast cancer cells with different phenotypes, we demonstrated the capability of 9cRA to modulate myotrophin (Mtpn) and miR-375 expressions. The 9cRA effect in pancreatic β-cells line INS-1 832/13 point out a decreased expression of Mptn at both mRNA and protein levels associated to a concomitant increase of miR-375. We also studied the effect of this molecule on 3T3-L1 pre-adipocytes cells demonstrating a down-regulation of Mtpn and a dramatic increase of miR-375. Moreover, in the in vitro breast cancer model such as MDA-MB-231 and MCF-7 cells, 9cRA showed different effect on both Mtpn and miR-375 expression. In INS-1 832/13, 3T3-L1 pre-adipocytes and MCF-7 but not in MDA-MB-231, the effect of 9cRA on Mptn gene expression and its miR was under the control of RARs and RXRs receptors, as revealed by the exposure of these cell line to LE540 or HX603 receptor antagonists. In our findings 9cRA emerges has a hormone with a regulatory action on miR-375 that in most cases interfere with Mtpn expression.

Cañete A, Cano E, Muñoz-Chápuli R, Carmona R
Role of Vitamin A/Retinoic Acid in Regulation of Embryonic and Adult Hematopoiesis.
Nutrients. 2017; 9(2) [PubMed] Free Access to Full Article Related Publications
Vitamin A is an essential micronutrient throughout life. Its physiologically active metabolite retinoic acid (RA), acting through nuclear retinoic acid receptors (RARs), is a potent regulator of patterning during embryonic development, as well as being necessary for adult tissue homeostasis. Vitamin A deficiency during pregnancy increases risk of maternal night blindness and anemia and may be a cause of congenital malformations. Childhood Vitamin A deficiency can cause xerophthalmia, lower resistance to infection and increased risk of mortality. RA signaling appears to be essential for expression of genes involved in developmental hematopoiesis, regulating the endothelial/blood cells balance in the yolk sac, promoting the hemogenic program in the aorta-gonad-mesonephros area and stimulating eryrthropoiesis in fetal liver by activating the expression of erythropoietin. In adults, RA signaling regulates differentiation of granulocytes and enhances erythropoiesis. Vitamin A may facilitate iron absorption and metabolism to prevent anemia and plays a key role in mucosal immune responses, modulating the function of regulatory T cells. Furthermore, defective RA/RARα signaling is involved in the pathogenesis of acute promyelocytic leukemia due to a failure in differentiation of promyelocytes. This review focuses on the different roles played by vitamin A/RA signaling in physiological and pathological mouse hematopoiesis duddurring both, embryonic and adult life, and the consequences of vitamin A deficiency for the blood system.

Kim YS, Kim E, Park YJ, Kim Y
Retinoic acid receptor β enhanced the anti-cancer stem cells effect of β-carotene by down-regulating expression of delta-like 1 homologue in human neuroblastoma cells.
Biochem Biophys Res Commun. 2016; 480(2):254-260 [PubMed] Related Publications
Neuroblastoma (NB) is childhood malignancy that retains characteristics of cancer stem cells (CSCs). Targeting the CSCs is one of the therapeutic strategies proposed to achieve complete remission of NB. β-carotene (BC), an active precursor of retinoids, is a well-known antioxidant reported to possess anti-CSCs effects. Here, we investigated the involvement of retinoic acid receptors (RARs) in the anti-CSCs effects of BC. Treatment with BC or retinoic acid (RA) upregulated RARβ mRNA expression in two NB cell lines. Inhibition of RARβ using siRNA up-regulated gene expression of delta-like 1 homologue (DLK1), a marker of CSCs. To understand the molecular mechanisms of RARβ-mediated inhibition of DLK1, four retinoic acid receptor elements (RAREs) were identified in the promoter of DLK1. Chromatin immunoprecipitation assays indicated that RARβ bound directly to a RARE in the DLK1 promoter region. Knock-down of RARβ also increased the self-renewal capacity of NB cells, which was suppressed by BC. Taken together, this study provided evidence that the therapeutic anti-CSC effects of BC depend on RARβ and its ability to interact with and down-regulate the CSCs marker, DLK1.

Muñiz-Hernández S, Huerta-Yepez S, Hernández-Pedro N, et al.
Association between nuclear expression of retinoic acid receptor alpha and beta and clinicopathological features and prognosis of advanced non-small cell lung cancer.
Int J Clin Oncol. 2016; 21(6):1051-1061 [PubMed] Related Publications
BACKGROUND: Transcription factors such as retinoic acid receptor alpha (RARα) and beta (RARβ) and Yin Yang 1 (YY1) are associated with the progression of non-small cell lung cancer (NSCLC). In particular, a lack of RARβ expression is associated with NSCLC development. The aim of this study was to analyze the expression of RARα, RARβ and YY1 and their relationship with prognosis in patients with advanced NSCLC.
METHODS: The expression of RARα, RARβ and YY1 was assessed by immunohistochemistry and quantitative computerized image software.
RESULTS: Eighty-five patients treated with platinum-based chemotherapy were included in the analysis. The mean and standard deviation of the nuclear expression of RARα, RARβ and YY1 were 184.5 ± 124.4, 18 ± 27 and 16.6 ± 20.5, respectively. The nuclear expression of RARβ was associated with the nuclear expression of YY1 (R
CONCLUSION: Our study suggests that the loss of RARs is associated with a worse prognosis and these receptors could be a potential molecular target for NSCLC.

Uray IP, Dmitrovsky E, Brown PH
Retinoids and rexinoids in cancer prevention: from laboratory to clinic.
Semin Oncol. 2016; 43(1):49-64 [PubMed] Free Access to Full Article Related Publications
Early in the age of modern medicine the consequences of vitamin A deficiency drew attention to the fundamental link between retinoid-dependent homeostatic regulation and malignant hyperproliferative diseases. The term "retinoid" includes a handful of endogenous and a large group of synthetic derivatives of vitamin A. These multifunctional lipid-soluble compounds directly regulate target genes of specific biological functions and critical signaling pathways to orchestrate complex functions from vision to development, metabolism, and inflammation. Many of the retinoid activities on the cellular level have been well characterized and translated to the regulation of processes like differentiation and cell death, which play critical roles in the outcome of malignant transformation of tissues. In fact, retinoid-based differentiation therapy of acute promyelocytic leukemia was one of the first successful examples of molecularly targeted treatment strategies. The selectivity, high receptor binding affinity and the ability of retinoids to directly modulate gene expression programs present a distinct pharmacological opportunity for cancer treatment and prevention. However, to fully exploit their potential, the adverse effects of retinoids must be averted. In this review we provide an overview of the biology of retinoid (activated by nuclear retinoic acid receptors [RARs]) and rexinoid (engaged by nuclear retinoid X receptors [RXRs]) action concluded from a long line of preclinical studies, in relation to normal and transformed states of cells. We will also discuss the past and current uses of retinoids in the treatment of malignancies, the potential of rexinoids in the cancer prevention setting, both as single agents and in combinations.

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.

Park SW, Joo YH, Jung SH, et al.
Chromosomal aberrations and prognosis in patients with concomitant chemoradiotherapy for resected head and neck cancer.
Oncol Rep. 2016; 35(4):2207-15 [PubMed] Related Publications
Although concomitant chemoradiotherapy (CCRT) has recently become a mainstay of a primary treatment modality in advanced head and neck squamous cell carcinoma (HNSCC), some of the patients experience CCRT failure. If we can predict the CCRT outcomes, we can reduce unnecessary CCRT avoiding risk of CCRT‑related complication. We aimed to identify genetic alteration markers related to treatment failure in HNSCC patients who underwent radical surgery and CCRT. Genome‑wide copy number alterations (CNAs) were analyzed in 18 HNSCC patients with (n=9) or without (n=9) recurrence using oligoarray‑comparative genomic hybridization and candidate CNAs were validated by quantitative RT‑PCR. A total of 15 recurrently altered regions (RARs) were identified in the 18 HNSCC cases. Among them, two RARs were significantly associated with CCRT‑failure: copy number gained RARs of 7p11.2 harboring EGFR (P=0.029) and 18p11.32 harboring TYMS gene (P=0.029). Three RARs (7p11.2, 9p21.3 and 18p11.32) were significantly associated with poor disease‑specific survival in univariate analysis, and 7p11.2 was consistently significant in the multivariate analysis (HR 40.68, P=0.003). In conclusion, we defined novel genomic alterations associated with CCRT‑failure: 7p11.2 (EGFR) and 18p11.32 (TYMS). Our results provide useful clues for the elucidation of the molecular pathogenesis of HNSCC and to predict CCRT‑failure.

Zhang W, Levi L, Banerjee P, et al.
Kruppel-like factor 2 suppresses mammary carcinoma growth by regulating retinoic acid signaling.
Oncotarget. 2015; 6(34):35830-42 [PubMed] Free Access to Full Article Related Publications
The transcription factor Kruppel-like factor 2 (KLF2) displays anticarcinogenic activities but the mechanism that underlies this activity is unknown. We show here that KLF2 is markedly downregulated in human breast cancers and that its expression positively correlates with breast cancer patient survival. We show further that KLF2 suppresses tumor development by controlling the transcriptional activity of the vitamin A metabolite retinoic acid (RA). RA regulates gene transcription by activating two types of nuclear receptors: RA receptors (RARs), which inhibit tumor development, and peroxisome proliferator-activated receptor β/δ (PPARβ/δ), which promotes tumorigenesis. The partitioning of RA between these receptors is regulated by two carrier proteins: cellular retinoic acid-binding protein 2 (CRABP2), which delivers RA to RARs, and fatty acid-binding protein 5 (FABP5), which shuttles ligands to PPARβ/δ. We show that KLF2 induces the expression of CRABP2 and RARγ and inhibits the expression FABP5 and PPARβ/δ thereby shifting RA signaling from the pro-carcinogenic FABP5/PPARβ/δ to the growth-suppressing CRABP2/RAR path. The data thus reveal that KLF2 suppresses tumor growth by controlling the transcriptional activities of RA.

Zaragozá R, García-Trevijano ER, Lluch A, et al.
Involvement of Different networks in mammary gland involution after the pregnancy/lactation cycle: Implications in breast cancer.
IUBMB Life. 2015; 67(4):227-38 [PubMed] Related Publications
Early pregnancy is associated with a reduction in a woman's lifetime risk for breast cancer. However, different studies have demonstrated an increase in breast cancer risk in the years immediately following pregnancy. Early and long-term risk is even higher if the mother age is above 35 years at the time of first parity. The proinflammatory microenvironment within the mammary gland after pregnancy renders an "ideal niche" for oncogenic events. Signaling pathways involved in programmed cell death and tissue remodeling during involution are also activated in breast cancer. Herein, the major signaling pathways involved in mammary gland involution, signal transducer and activator of transcription (STAT3), nuclear factor-kappa B (NF-κB), transforming growth factor beta (TGFβ), and retinoid acid receptors (RARs)/retinoid X receptors (RXRs), are reviewed as part of the complex network of signaling pathways that crosstalk in a contextual-dependent manner. These factors, also involved in breast cancer development, are important regulatory nodes for signaling amplification after weaning. Indeed, during involution, p65/p300 target genes such as MMP9, Capn1, and Capn2 are upregulated. Elevated expression and activities of these proteases in breast cancer have been extensively documented. The role of these proteases during mammary gland involution is further discussed. MMPs, calpains, and cathepsins exert their effect by modification of the extracellular matrix and intracellular proteins. Calpains, activated in the mammary gland during involution, cleave several proteins located in cell membrane, lysosomes, mitochondria, and nuclei favoring cell death. Besides, during this period, Capn1 is most probably involved in the modulation of preadipocyte differentiation through chromatin remodeling. Calpains can be implicated in cell anchoring loss, providing a proper microenvironment for tumor growth. A better understanding of the role of any of these proteases in tumorigenesis may yield novel therapeutic targets or prognostic markers for breast cancer.

Janesick A, Wu SC, Blumberg B
Retinoic acid signaling and neuronal differentiation.
Cell Mol Life Sci. 2015; 72(8):1559-76 [PubMed] Related Publications
The identification of neurological symptoms caused by vitamin A deficiency pointed to a critical, early developmental role of vitamin A and its metabolite, retinoic acid (RA). The ability of RA to induce post-mitotic, neural phenotypes in various stem cells, in vitro, served as early evidence that RA is involved in the switch between proliferation and differentiation. In vivo studies have expanded this "opposing signal" model, and the number of primary neurons an embryo develops is now known to depend critically on the levels and spatial distribution of RA. The proneural and neurogenic transcription factors that control the exit of neural progenitors from the cell cycle and allow primary neurons to develop are partly elucidated, but the downstream effectors of RA receptor (RAR) signaling (many of which are putative cell cycle regulators) remain largely unidentified. The molecular mechanisms underlying RA-induced primary neurogenesis in anamniote embryos are starting to be revealed; however, these data have been not been extended to amniote embryos. There is growing evidence that bona fide RARs are found in some mollusks and other invertebrates, but little is known about their necessity or functions in neurogenesis. One normal function of RA is to regulate the cell cycle to halt proliferation, and loss of RA signaling is associated with dedifferentiation and the development of cancer. Identifying the genes and pathways that mediate cell cycle exit downstream of RA will be critical for our understanding of how to target tumor differentiation. Overall, elucidating the molecular details of RAR-regulated neurogenesis will be decisive for developing and understanding neural proliferation-differentiation switches throughout development.

di Masi A, Leboffe L, De Marinis E, et al.
Retinoic acid receptors: from molecular mechanisms to cancer therapy.
Mol Aspects Med. 2015; 41:1-115 [PubMed] Related Publications
Retinoic acid (RA), the major bioactive metabolite of retinol or vitamin A, induces a spectrum of pleiotropic effects in cell growth and differentiation that are relevant for embryonic development and adult physiology. The RA activity is mediated primarily by members of the retinoic acid receptor (RAR) subfamily, namely RARα, RARβ and RARγ, which belong to the nuclear receptor (NR) superfamily of transcription factors. RARs form heterodimers with members of the retinoid X receptor (RXR) subfamily and act as ligand-regulated transcription factors through binding specific RA response elements (RAREs) located in target genes promoters. RARs also have non-genomic effects and activate kinase signaling pathways, which fine-tune the transcription of the RA target genes. The disruption of RA signaling pathways is thought to underlie the etiology of a number of hematological and non-hematological malignancies, including leukemias, skin cancer, head/neck cancer, lung cancer, breast cancer, ovarian cancer, prostate cancer, renal cell carcinoma, pancreatic cancer, liver cancer, glioblastoma and neuroblastoma. Of note, RA and its derivatives (retinoids) are employed as potential chemotherapeutic or chemopreventive agents because of their differentiation, anti-proliferative, pro-apoptotic, and anti-oxidant effects. In humans, retinoids reverse premalignant epithelial lesions, induce the differentiation of myeloid normal and leukemic cells, and prevent lung, liver, and breast cancer. Here, we provide an overview of the biochemical and molecular mechanisms that regulate the RA and retinoid signaling pathways. Moreover, mechanisms through which deregulation of RA signaling pathways ultimately impact on cancer are examined. Finally, the therapeutic effects of retinoids are reported.

Zoi K, Cross NC
Molecular pathogenesis of atypical CML, CMML and MDS/MPN-unclassifiable.
Int J Hematol. 2015; 101(3):229-42 [PubMed] Related Publications
According to the 2008 WHO classification, the category of myelodysplastic/myeloproliferative neoplasms (MDS/MPN) includes atypical chronic myeloid leukaemia (aCML), chronic myelomonocytic leukaemia (CMML), MDS/MPN-unclassifiable (MDS/MPN-U), juvenile myelomonocytic leukaemia (JMML) and a "provisional" entity, refractory anaemia with ring sideroblasts and thrombocytosis (RARS-T). The remarkable progress in our understanding of the somatic pathogenesis of MDS/MPN has made it clear that there is considerable overlap among these diseases at the molecular level, as well as layers of unexpected complexity. Deregulation of signalling plays an important role in many cases, and is clearly linked to more highly proliferative disease. Other mutations affect a range of other essential, interrelated cellular mechanisms, including epigenetic regulation, RNA splicing, transcription, and DNA damage response. The various combinations of mutations indicate a multi-step pathogenesis, which likely contributes to the marked clinical heterogeneity of these disorders. The delineation of complex clonal architectures may serve as the cornerstone for the identification of novel therapeutic targets and lead to better patient outcomes. This review summarizes some of the current knowledge of molecular pathogenetic lesions in the MDS/MPN subtypes that are seen in adults: atypical CML, CMML and MDS/MPN-U.

Nervi C, Grignani F
RARs and microRNAs.
Subcell Biochem. 2014; 70:151-79 [PubMed] Related Publications
MicroRNA MicroRNA s (miRNAs) are small noncoding RNAs acting as endogenous regulators of gene expression. Their discovery is one of the major recent breakthroughs in molecular biology. miRNAs establish a multiplicity of relationships with target mRNAs and exert pleiotropic biological effects in many cell physiological pathways during development and adult life. The dynamic nature of gene expression regulation by Retinoic Acid Retinoic acid (RA) is consistent with an extensive functional interplay with miRNA activities. In fact, RA regulates the expression of many different miRNAs, thus suggesting a relevant function of miRNAs in RA-controlled gene expression programmes. miRNAs have been extensively studied as targets and mediators of the biological activity of RA during embryonic development as well as in normal and neoplastic cells. However, relatively few studies have experimentally explored the direct contribution of miRNA function to the RA signalling pathway. Here, we provide an overview of the mechanistic aspects that allow miRNA biogenesis, functional activation and regulation, focusing on recent evidence that highlights a functional interplay between miRNAs and RA-regulated molecular networks. We report examples of tissue-specific roles of miRNAs modulated by RA in stem cell pluripotency maintenance and regeneration, embryonic development, hematopoietic and neural differentiation, and other biological model systems, underlining their role in disease pathogenesis. We also address novel areas of research linking the RA signalling pathway to the nuclear activity of miRNAs.

Li M, Sun Y, Guan X, et al.
Advanced progress on the relationship between RA and its receptors and malignant tumors.
Crit Rev Oncol Hematol. 2014; 91(3):271-82 [PubMed] Related Publications
Retinoic acid (RA) is an active derivative of vitamin A, and it has different isomers, including ATRA (all-trans-retinoic acid), 13-cRA (13-cis-retinoic acid) and 9-cRA (9-cis-retinoic acid), etc. Combining with RARs and RXRs, RA plays important roles not only in embryonic development but also in cellular growth and differentiation through transcriptional regulation of its target genes. Following the successful application in the differentiation therapy of acute promyelocytic leukemia (APL) in clinical, recent studies have found that the disturbance of RA signal transduction was also related to differentiation, proliferation or apoptosis of tumor cells. To develop novel mechanisms-based differentiation therapy for other tumors, the relationship between RA or its receptors and tumors will be summarized in this review.

Orfali N, McKenna SL, Cahill MR, et al.
Retinoid receptor signaling and autophagy in acute promyelocytic leukemia.
Exp Cell Res. 2014; 324(1):1-12 [PubMed] Free Access to Full Article Related Publications
Retinoids are a family of signaling molecules derived from vitamin A with well established roles in cellular differentiation. Physiologically active retinoids mediate transcriptional effects on cells through interactions with retinoic acid (RARs) and retinoid-X (RXR) receptors. Chromosomal translocations involving the RARα gene, which lead to impaired retinoid signaling, are implicated in acute promyelocytic leukemia (APL). All-trans-retinoic acid (ATRA), alone and in combination with arsenic trioxide (ATO), restores differentiation in APL cells and promotes degradation of the abnormal oncogenic fusion protein through several proteolytic mechanisms. RARα fusion-protein elimination is emerging as critical to obtaining sustained remission and long-term cure in APL. Autophagy is a degradative cellular pathway involved in protein turnover. Both ATRA and ATO also induce autophagy in APL cells. Enhancing autophagy may therefore be of therapeutic benefit in resistant APL and could broaden the application of differentiation therapy to other cancers. Here we discuss retinoid signaling in hematopoiesis, leukemogenesis, and APL treatment. We highlight autophagy as a potential important regulator in anti-leukemic strategies.

He Y, Gong J, Wang Y, et al.
Potentially functional polymorphisms in aminoacyl-tRNA synthetases genes are associated with breast cancer risk in a Chinese population.
Mol Carcinog. 2015; 54(7):577-83 [PubMed] Related Publications
Aminoacyl-tRNA synthetases (ARSs) are responsible for cellular protein synthesis and cell viability involving in various process of tumorigenesis. We hypothesized that genetic variants in core ARSs genes may play an important role in the development of breast cancer. Thus, we conducted a case-control study including 1064 breast cancer cases and 1073 cancer-free controls to evaluate the associations of 28 potentially functional polymorphisms in 12 core ARSs genes (AARS, CARS, EPRS, HARS, KARS, LARS, MARS, QARS, RARS, VARS, WARS, and YARS) with breast cancer risk. We found significant associations with the risk of breast cancer for rs34087264 in AARS [odds ratio (OR) = 1.15, 95% confidence interval (CI) = 1.01-1.31], rs801186 in HARS (OR = 1.29, 95% CI = 1.08-1.54), rs193466 in RARS (OR = 1.17, 95% CI = 1.02-1.35), and rs2273802 in WARS (OR = 1.14, 95% CI = 1.01-1.30). We further observed significant interactions between rs2273802 and age at the first live birth (P = 0.041), and between rs801186 and age on breast cancer risk (P = 0.018). Combined analysis of these four SNPs showed a significant allele-dosage association between the number of risk alleles and breast cancer risk (Ptrend  = 2.00 × 10(-4) ). Compared with individuals with "0-2" risk alleles, those carrying "3," "4," or "5 or more" risk alleles had a 1.32 (95% CI = 1.07-1.64), 1.48 (95% CI = 1.45-1.91), or 1.60 folds (95% CI = 1.06-2.41) risk of breast cancer, respectively. These findings indicate that genetic variants in core ARSs genes may modify the individual susceptibility to breast cancer in Chinese population.

Malcovati L, Cazzola M
Refractory anemia with ring sideroblasts.
Best Pract Res Clin Haematol. 2013; 26(4):377-85 [PubMed] Related Publications
Refractory anemia with ring sideroblasts (RARS) is a subtype of myelodysplastic syndrome (MDS) characterized by 15% or more ring sideroblasts in the bone marrow according to the WHO classification. After Perls staining, ring sideroblasts are defined as erythroblasts in which there are 5 or more siderotic granules covering at least a third of the nuclear circumference. The iron deposited in perinuclear mitochondria of ring sideroblasts is present in the form of mitochondrial ferritin. The molecular basis of MDS with ring sideroblasts has remained unknown until recently. In 2011, whole exome sequencing studies revealed somatic mutations of SF3B1, a gene encoding a core component of RNA splicing machinery, in myelodysplasia with ring sideroblasts. The close relationship between SF3B1 mutation and ring sideroblasts is consistent with a causal relationship, and makes SF3B1 the first gene to be associated with a specific morphological feature in MDS. RARS is mainly characterized by isolated anemia due to ineffective erythropoiesis, and its clinical course is generally benign, although there is a tendency to worsening of anemia in most patients over time. By contrast, refractory cytopenia with multilineage dysplasia and ring sideroblasts (RCMD-RS) is characterized by pancytopenia and dysplasia in two or more myeloid cell lineages. More importantly, patients with RCMD-RS have a higher risk of developing bone marrow failure or progressing to acute myeloid leukemia (AML). Refractory anemia with ring sideroblasts (RARS-T) associated with marked thrombocytosis is a myelodysplastic/myeloproliferative neoplasm associated with both SF3B1 and JAK2 or MPL mutations. RARS-T may develop from an SF3B1 mutated RARS through the acquisition of a JAK2 or MPL mutations in a subclone of hematopoietic cells.

Qi LN, Li LQ, Chen YY, et al.
Genome-wide and differential proteomic analysis of hepatitis B virus and aflatoxin B1 related hepatocellular carcinoma in Guangxi, China.
PLoS One. 2013; 8(12):e83465 [PubMed] Free Access to Full Article Related Publications
Both hepatitis B virus (HBV) and aflatoxin B1 (AFB1) exposure can cause liver damage as well as increase the probability of hepatocellular carcinoma (HCC). To investigate the underlying genetic changes that may influence development of HCC associated with HBV infection and AFB1 exposure, HCC patients were subdivided into 4 groups depending upon HBV and AFB1 exposure status: (HBV(+)/AFB1(+), HBV(+)/AFB1(-), HBV(-)/AFB1(+), HBV(-)/AFB1(-)). Genetic abnormalities and protein expression profiles were analyzed by array-based comparative genomic hybridization and isobaric tagging for quantitation. A total of 573 chromosomal aberrations (CNAs) including 184 increased and 389 decreased were detected in our study population. Twenty-five recurrently altered regions (RARs; chromosomal alterations observed in ≥10 patients) in chromosomes were identified. Loss of 4q13.3-q35.2, 13q12.1-q21.2 and gain of 7q11.2-q35 were observed with a higher frequency in the HBV(+)/AFB1(+), HBV(+)/AFB1(-) and HBV(-)/AFB1(+) groups compared to the HBV(-)/AFB(-) group. Loss of 8p12-p23.2 was associated with high TNM stage tumors (P = 0.038) and was an unfavorable prognostic factor for tumor-free survival (P =0.045). A total of 133 differentially expressed proteins were identified in iTRAQ proteomics analysis, 69 (51.8%) of which mapped within identified RARs. The most common biological processes affected by HBV and AFB1 status in HCC tumorigenesis were detoxification and drug metabolism pathways, antigen processing and anti-apoptosis pathways. Expression of AKR1B10 was increased significantly in the HBV(+)/AFB1(+) and HBV(-)/AFB1(+) groups. A significant correlation between the expression of AKR1B10 mRNA and protein levels as well as AKR1B10 copy number was observered, which suggest that AKR1B10 may play a role in AFB1-related hepatocarcinogenesis. In summary, a number of genetic and gene expression alterations were found to be associated with HBV and AFB1- related HCC. The possible synergistic effects of HBV and AFB1 in hepatocarcinogenesis warrant further investigations.

Joo YH, Park SW, Jung SH, et al.
Recurrent loss of the FHIT gene and its impact on lymphatic metastasis in early oral squamous cell carcinoma.
Acta Otolaryngol. 2013; 133(9):992-9 [PubMed] Related Publications
CONCLUSION: Our findings show that copy number loss of FHIT is associated with lymph node metastasis (LNM) and suggest that the down-regulation of Fhit indicates poor prognosis in early oral squamous cell carcinoma (OSCC).
OBJECTIVES: The purpose of this study was to identify alterations in genetic markers related to LNM in early OSCC.
METHODS: Genome-wide copy number alterations were analyzed in 14 early OSCCs with (n = 7) or without (n = 7) cervical LNM using 180K array-comparative genomic hybridization. To explore the prognostic implications of the most significantly associated genetic alteration with cervical LNM, immunohistochemical analysis was conducted in 30 OSCCs.
RESULTS: A total of 11 recurrently altered regions (RARs) were identified in the 14 OSCC cases. Six RARs on chromosomes 3p26-3p14, 5q22, and 9p21 were found to be significantly more common in early OSCC with LNM (p < 0.05). Among these, loss of 3p14.2 (where the FHIT gene is located) was the most frequent (five of seven patients with LNM, and none of seven without LNM), and most significantly associated with cervical LNM (p = 0.005). Fhit immunohistochemical staining of 30 OSCCs showed that Fhit negativity was associated with cervical LNM (p = 0.032) and poor disease-specific survival (p = 0.045).

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.

Wang S, Wang Z, Lin S, et al.
Revealing a natural marine product as a novel agonist for retinoic acid receptors with a unique binding mode and inhibitory effects on cancer cells.
Biochem J. 2012; 446(1):79-87 [PubMed] Related Publications
Retinoids display anti-tumour activity on various cancer cells and therefore have been used as important therapeutic agents. However, adverse side effects and RA (retinoic acid) resistance limit further development and clinical application of retinoid-based therapeutic agents. We report in the present paper the identification of a natural marine product that activates RARs (RA receptors) with a chemical structure distinct from retinoids by high-throughput compound library screening. Luffariellolide was uncovered as a novel RAR agonist by inducing co-activator binding to these receptors in vitro, further inhibiting cell growth and regulating RAR target genes in various cancer cells. Structural and molecular studies unravelled a unique binding mode of this natural ligand to RARs with an unexpected covalent modification on the RAR. Functional characterization further revealed that luffariellolide displays chemotherapeutic potentials for overcoming RA resistance in colon cancer cells, suggesting that luffariellolide may represent a unique template for designing novel non-retinoid compounds with advantages over current RA drugs.

Cras A, Politis B, Balitrand N, et al.
Bexarotene via CBP/p300 induces suppression of NF-κB-dependent cell growth and invasion in thyroid cancer.
Clin Cancer Res. 2012; 18(2):442-53 [PubMed] Related Publications
PURPOSE: Retinoic acid (RA) treatment has been used for redifferentiation of metastatic thyroid cancer with loss of radioiodine uptake. The aim of this study was to improve the understanding of RA resistance and investigate the role of bexarotene in thyroid cancer cells.
EXPERIMENTAL DESIGN: A model of thyroid cancer cell lines with differential response to RA was used to evaluate the biological effects of retinoid and rexinoid and to correlate this with RA receptor levels. Subsequently, thyroid cancer patients were treated with 13-cis RA and bexarotene and response evaluated on radioiodine uptake reinduction on posttherapy scan and conventional imaging.
RESULTS: In thyroid cancer patients, 13-cis RA resistance can be bypassed in some tumors by bexarotene. A decreased tumor growth without differentiation was observed confirming our in vitro data. Indeed, we show that ligands of RARs or RXRs exert different effects in thyroid cancer cell lines through either differentiation or inhibition of cell growth and invasion. These effects are associated with restoration of RARβ and RXRγ levels and downregulation of NF-κB targets genes. We show that bexarotene inhibits the transactivation potential of NF-κB in an RXR-dependent manner through decreased promoter permissiveness without interfering with NF-κB nuclear translocation and binding to its responsive elements. Inhibition of transcription results from the release of p300 coactivator from NF-κB target gene promoters and subsequent histone deacetylation.
CONCLUSION: This study highlights dual mechanisms by which retinoids and rexinoids may target cell tumorigenicity, not only via RARs and RXRs, as expected, but also via NF-κB pathway.

Ocadiz-Delgado R, Castañeda-Saucedo E, Indra AK, et al.
RXRα deletion and E6E7 oncogene expression are sufficient to induce cervical malignant lesions in vivo.
Cancer Lett. 2012; 317(2):226-36 [PubMed] Related Publications
Cervical cancer is the second leading cause of cancer deaths among women worldwide. High-Risk-Human Papillomaviruses (HR-HPVs) play an important etiologic role in the development of carcinoma of the uterine cervix. However, host factors are important in determining the outcome of genital HPV infection as most cervical precancerous lesions containing HR-HPVs do not progress to invasive carcinomas. Retinoids, acting through nuclear receptors (RARs, RXRs), play a crucial role in cervix development and homeostasis regulating growth and differentiation of a wide variety of cell types; indeed, they can inhibit cell proliferation, and induce cell differentiation or apoptotic cell death. Here we introduce a mouse model that develops spontaneously malignant cervical lesions allowing the study of the cooperative effect between HPV16E6E7 expression and the lack of RXRα in cervical cancer development. This model could be useful to study multistep carcinogenesis of uterine cervix tissue and might improve chemopreventive and chemotherapeutic strategies for this neoplasia.

Cassinat B, Zassadowski F, Ferry C, et al.
New role for granulocyte colony-stimulating factor-induced extracellular signal-regulated kinase 1/2 in histone modification and retinoic acid receptor α recruitment to gene promoters: relevance to acute promyelocytic leukemia cell differentiation.
Mol Cell Biol. 2011; 31(7):1409-18 [PubMed] Free Access to Full Article Related Publications
The induction of the granulocytic differentiation of leukemic cells by all-trans retinoic acid (RA) has been a major breakthrough in terms of survival for acute promyelocytic leukemia (APL) patients. Here we highlight the synergism and the underlying novel mechanism between RA and the granulocyte colony-stimulating factor (G-CSF) to restore differentiation of RA-refractory APL blasts. First, we show that in RA-refractory APL cells (UF-1 cell line), PML-RA receptor alpha (RARα) is not released from target promoters in response to RA, resulting in the maintenance of chromatin repression. Consequently, RARα cannot be recruited, and the RA target genes are not activated. We then deciphered how the combination of G-CSF and RA successfully restored the activation of RA target genes to levels achieved in RA-sensitive APL cells. We demonstrate that G-CSF restores RARα recruitment to target gene promoters through the activation of the extracellular signal-regulated kinase (ERK)/mitogen-activated protein kinase (MAPK) pathway and the subsequent derepression of chromatin. Thus, combinatorial activation of cytokines and RARs potentiates transcriptional activity through epigenetic modifications induced by specific signaling pathways.

Duong V, Rochette-Egly C
The molecular physiology of nuclear retinoic acid receptors. From health to disease.
Biochim Biophys Acta. 2011; 1812(8):1023-31 [PubMed] Related Publications
The nuclear retinoic acid (RA) receptors (RARα, β and γ) are transcriptional transregulators, which control the expression of specific gene subsets subsequently to ligand binding and to strictly controlled phosphorylation processes. Consequently RARs maintain homeostasis through the control of cell proliferation and differentiation. Today, it is admitted that, analogous to the paradigm established by the hematopoietic system, most adult tissues depict a differentiation hierarchy starting from rare stem cells. Here we highlight that the integrity of RARs is absolutely required for homeostasis in adults. Indeed, strictly controlled levels of RARs are necessary for the correct balance between self-renewal and differentiation of tissue stem cells. In addition, loss, accumulation, mutations or aberrant modifications of a specific RAR lead to uncontrolled proliferation and/or to differentiation block and thereby to cancer. This article is part of a Special Issue entitled: Translating nuclear receptors from health to disease.

Hua S, Kittler R, White KP
Genomic antagonism between retinoic acid and estrogen signaling in breast cancer.
Cell. 2009; 137(7):1259-71 [PubMed] Free Access to Full Article Related Publications
Retinoic acid (RA) triggers antiproliferative effects in tumor cells, and therefore RA and its synthetic analogs have great potential as anticarcinogenic agents. Retinoic acid receptors (RARs) mediate RA effects by directly regulating gene expression. To define the genetic network regulated by RARs in breast cancer, we identified RAR genomic targets using chromatin immunoprecipitation and expression analysis. We found that RAR binding throughout the genome is highly coincident with estrogen receptor alpha (ERalpha) binding, resulting in a widespread crosstalk of RA and estrogen signaling to antagonistically regulate breast cancer-associated genes. ERalpha- and RAR-binding sites appear to be coevolved on a large scale throughout the human genome, often resulting in competitive binding activity at nearby or overlapping cis-regulatory elements. The highly coordinated intersection between these two critical nuclear hormone receptor signaling pathways provides a global mechanism for balancing gene expression output via local regulatory interactions dispersed throughout the genome.

Luo P, Lin M, Lin M, et al.
Function of retinoid acid receptor alpha and p21 in all-trans-retinoic acid-induced acute T-lymphoblastic leukemia apoptosis.
Leuk Lymphoma. 2009; 50(7):1183-9 [PubMed] Related Publications
All-trans-retinoic acid (ATRA) is a morphogenetic signalling molecule derived from vitamin A and is used clinically to target acute promyelocytic leukemia by inducing differentiation of immature blood cells. Retinoid signals are mediated by retinoic acid (RA) receptors (RARs) and retinoid X receptors (RXRs). Retinoic acid receptors consist of RARalpha, RARbeta and RARgamma isotypes. Among these components, RARalpha is preferentially bound to ATRA, which is used to treat acute T-lymphoblastic leukemia, yet the conditions and mechanisms remain unknown. In this study, we have demonstrated that, in human acute T-lymphoblastic leukemia Molt3 cells, inhibition of RA-induced proliferation results from massive cell death characterised by apoptosis. The effect of ATRA:RARalpha binding on apoptosis in Molt3 cells has been investigated. Consequently, it has been shown that, in RA-treated Molt3 cells, upregulation of p21 due to RA accompanies caspase 3/PARP activation which precedes the occurrence of apoptosis.

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