Gene Summary

Gene:YBX1; Y box binding protein 1
Aliases: YB1, BP-8, CSDB, DBPB, YB-1, CSDA2, NSEP1, NSEP-1, MDR-NF1
Databases:OMIM, VEGA, HGNC, Ensembl, GeneCard, Gene
Protein:nuclease-sensitive element-binding protein 1
Source:NCBIAccessed: 17 August, 2015


What does this gene/protein do?
Show (27)
Pathways:What pathways are this gene/protein implicaed in?
Show (1)

Cancer Overview

Research Indicators

Publications Per Year (1990-2015)
Graph generated 17 August 2015 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.

  • RNA Interference
  • CCAAT-Enhancer-Binding Proteins
  • Transcription
  • Nuclear Proteins
  • DNA-Binding Proteins
  • Breast Cancer
  • RNA-Binding Proteins
  • Transcription Factors
  • Biological Models
  • Prostate Cancer
  • Phosphorylation
  • Antineoplastic Agents
  • MAP Kinase Signaling System
  • Neoplasm Proteins
  • siRNA
  • Tumor Markers
  • Base Sequence
  • Chromosome 1
  • Brain Tumours
  • Cancer Gene Expression Regulation
  • Melanoma
  • Binding Sites
  • NFI Transcription Factors
  • Brain Tumours
  • Promoter Regions
  • Neoplastic Cell Transformation
  • Gene Expression Profiling
  • AKT1
  • Signal Transduction
  • Messenger RNA
  • Immunohistochemistry
  • Drug Resistance
  • Western Blotting
  • Molecular Sequence Data
  • TOR Serine-Threonine Kinases
  • Transfection
  • P-Glycoprotein
  • Protein Binding
  • Cell Proliferation
  • Apoptosis
Tag cloud generated 17 August, 2015 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: YBX1 (cancer-related)

Liu TT, Arango-Argoty G, Li Z, et al.
Noncoding RNAs that associate with YB-1 alter proliferation in prostate cancer cells.
RNA. 2015; 21(6):1159-72 [PubMed] Article available free on PMC after 01/06/2016 Related Publications
The highly conserved, multifunctional YB-1 is a powerful breast cancer prognostic indicator. We report on a pervasive role for YB-1 in which it associates with thousands of nonpolyadenylated short RNAs (shyRNAs) that are further processed into small RNAs (smyRNAs). Many of these RNAs have previously been identified as functional noncoding RNAs (http://www.johnlab.org/YB1). We identified a novel, abundant, 3'-modified short RNA antisense to Dicer1 (Shad1) that colocalizes with YB-1 to P-bodies and stress granules. The expression of Shad1 was shown to correlate with that of YB-1 and whose inhibition leads to an increase in cell proliferation. Additionally, Shad1 influences the expression of additional prognostic markers of cancer progression such as DLX2 and IGFBP2. We propose that the examination of these noncoding RNAs could lead to better understanding of prostate cancer progression.

Somasekharan SP, El-Naggar A, Leprivier G, et al.
YB-1 regulates stress granule formation and tumor progression by translationally activating G3BP1.
J Cell Biol. 2015; 208(7):913-29 [PubMed] Article available free on PMC after 30/09/2015 Related Publications
Under cell stress, global protein synthesis is inhibited to preserve energy. One mechanism is to sequester and silence mRNAs in ribonucleoprotein complexes known as stress granules (SGs), which contain translationally silent mRNAs, preinitiation factors, and RNA-binding proteins. Y-box binding protein 1 (YB-1) localizes to SGs, but its role in SG biology is unknown. We now report that YB-1 directly binds to and translationally activates the 5' untranslated region (UTR) of G3BP1 mRNAs, thereby controlling the availability of the G3BP1 SG nucleator for SG assembly. YB-1 inactivation in human sarcoma cells dramatically reduces G3BP1 and SG formation in vitro. YB-1 and G3BP1 expression are highly correlated in human sarcomas, and elevated G3BP1 expression correlates with poor survival. Finally, G3BP1 down-regulation in sarcoma xenografts prevents in vivo SG formation and tumor invasion, and completely blocks lung metastasis in mouse models. Together, these findings demonstrate a critical role for YB-1 in SG formation through translational activation of G3BP1, and highlight novel functions for SGs in tumor progression.

Cybulski M, Jarosz B, Nowakowski A, et al.
Cyclin A correlates with YB1, progression and resistance to chemotherapy in human epithelial ovarian cancer.
Anticancer Res. 2015; 35(3):1715-21 [PubMed] Related Publications
BACKGROUND: Cyclin A is a cell-cycle regulatory gene and its overexpression promotes tumor cell growth. Y-Box-binding protein 1 (YB1) is a transcription/translation factor involved in tumor growth, invasion, and drug resistance. We investigated whether an association exists between protein products of these genes in epithelial ovarian cancer (EOC) specimens and clinicopathological parameters, patient response and EOC sensitivity to platinum-based first-line chemotherapy.
PATIENTS AND METHODS: Cyclin A and YB1 expression were analyzed by immunohistochemistry in 54 human primary EOC tissues. Immunolabeling of both proteins was graded according to their staining intensity (scale 0-3) and the proportion of immunostained cancer cells (scale 0-4) to obtain a staining index (SI; value=0-12).
RESULTS: Significantly higher cyclin A immunostaining (SI≥4) in EOC specimens was discovered in patients with advanced (International Federation of Gynaecology and Obstetrics (FIGO) III and IV, p=0.003), poorly differentiated (G3, p<0.001) tumors, and tumors of those with residual disease>1 cm (p=0.001). YB1 immunostaining was significantly higher in EOCs from patients with suboptimal debulking (p=0.025). Over-expression of cyclin A (SI≥9) in EOCs was significantly linked with poorer patient response (p=0.001) and higher resistance of tumors to platinum-based first-line chemotherapy (p=0.007), while immunolabeling of YB1 in EOCs was not significantly associated with either of these variables (p>0.05). Cyclin A expression was significantly and positively correlated with that of YB1 (R=0.588, p<0.001).
CONCLUSION: Increased cyclin A expression in EOC is related to a more aggressive tumor behavior and predicts the response of patients to first-line platinum-based chemotherapy.

Troiano A, Lomoriello IS, di Martino O, et al.
Y-box Binding Protein-1 Is Part of a Complex Molecular Network Linking ΔNp63α to the PI3K/akt Pathway in Cutaneous Squamous Cell Carcinoma.
J Cell Physiol. 2015; 230(9):2067-74 [PubMed] Related Publications
Cutaneous squamous cell carcinomas (SCCs) typically lack somatic oncogene-activating mutations and most of them contain p53 mutations. However, the presence of p53 mutations in skin premalignant lesions suggests that these represent early events during tumor progression and additional alterations may be required for SCC development. SCC cells frequently express high levels of ΔNp63α and Y-box binding 1 (YB-1 or YBX1) oncoproteins. Here, we show that knockdown of YB-1 in spontaneously immortalized HaCaT and non-metastatic SCC011 cells led to a dramatic decrease of ΔNp63α, cell detachment and death. In highly metastatic SCC022 cells, instead, YB-1 silencing induces PI3K/AKT signaling hyperactivation which counteracts the effect of YB-1 depletion and promotes cell survival. In summary, our results unveil a functional cross-talk between YB-1, ΔNp63α and the PI3K/AKT pathway critically governing survival of squamous carcinoma cells.

Feng T, Dzieran J, Gu X, et al.
Smad7 regulates compensatory hepatocyte proliferation in damaged mouse liver and positively relates to better clinical outcome in human hepatocellular carcinoma.
Clin Sci (Lond). 2015; 128(11):761-74 [PubMed] Related Publications
Transforming growth factor β (TGF-β) is cytostatic towards damage-induced compensatory hepatocyte proliferation. This function is frequently lost during hepatocarcinogenesis, thereby switching the TGF-β role from tumour suppressor to tumour promoter. In the present study, we investigate Smad7 overexpression as a pathophysiological mechanism for cytostatic TGF-β inhibition in liver damage and hepatocellular carcinoma (HCC). Transgenic hepatocyte-specific Smad7 overexpression in damaged liver of fumarylacetoacetate hydrolase (FAH)-deficient mice increased compensatory proliferation of hepatocytes. Similarly, modulation of Smad7 expression changed the sensitivity of Huh7, FLC-4, HLE and HLF HCC cell lines for cytostatic TGF-β effects. In our cohort of 140 HCC patients, Smad7 transcripts were elevated in 41.4% of HCC samples as compared with adjacent tissue, with significant positive correlation to tumour size, whereas low Smad7 expression levels were significantly associated with worse clinical outcome. Univariate and multivariate analyses indicate Smad7 levels as an independent predictor for overall (P<0.001) and disease-free survival (P=0.0123). Delineating a mechanism for Smad7 transcriptional regulation in HCC, we identified cold-shock Y-box protein-1 (YB-1), a multifunctional transcription factor. YB-1 RNAi reduced TGF-β-induced and endogenous Smad7 expression in Huh7 and FLC-4 cells respectively. YB-1 and Smad7 mRNA expression levels correlated positively (P<0.0001). Furthermore, nuclear co-localization of Smad7 and YB-1 proteins was present in cancer cells of those patients. In summary, the present study provides a YB-1/Smad7-mediated mechanism that interferes with anti-proliferative/tumour-suppressive TGF-β actions in a subgroup of HCC cells that may facilitate aspects of tumour progression.

Li AM, Dunham C, Tabori U, et al.
EZH2 expression is a prognostic factor in childhood intracranial ependymoma: a Canadian Pediatric Brain Tumor Consortium study.
Cancer. 2015; 121(9):1499-507 [PubMed] Related Publications
BACKGROUND: The cure rate for childhood intracranial ependymoma is approximately 70% in the setting of a gross total resection followed by radiation, but management remains challenging in patients with residual disease. Therefore, robust biomarkers are needed to guide the development of new targeted therapy. The authors evaluated the expression of several biomarkers in pediatric intracranial ependymoma and observed that the expression of enhancer of zeste homolog 2 (EZH2), a polycomb complex protein involved in epigenetic regulation of gene expression, was independently associated with poor survival.
METHODS: Tissue microarray immunostaining was performed on 180 ependymoma samples from 12 of 16 Canadian pediatric centers. Expression levels of EZH2, Ki-67, B lymphoma Moloney-murine leukemia virus insertion region 1 homolog, tumor protein 16 (P16), Y-box binding protein 1, phosphorylated protein kinase B (pAKT), and epidermal growth factor receptor were evaluated. Cox regression analyses were performed, and the Kaplan-Meier method was used to construct survival curves.
RESULTS: EZH2 expressed in 16% of tumors was associated with inferior 5-year overall survival. Ki-67 and pAKT levels were associated with a poor outcome in patients with posterior fossa ependymoma, and the absence of P16 was associated with a poor outcome in patients with supratentorial ependymoma. Multivariate analysis revealed that younger age and EZH2 expression (95% confidence interval, 1.1-36.0) were independent markers of a poor prognosis.
CONCLUSIONS: EZH2 is a novel, independent marker of a poor prognosis in patients with ependymoma, especially in those who have tumors located in the posterior fossa. EZH2, pAKT, and P16 are potential therapeutic targets, particularly for patients who have tumors in which standard gross total resection plus fractionated radiotherapy is not feasible.

Chen DB, Yang HJ
Comparison of gene regulatory networks of benign and malignant breast cancer samples with normal samples.
Genet Mol Res. 2014; 13(4):9453-62 [PubMed] Related Publications
The aim of this study was to explain the pathogenesis and deterioration process of breast cancer. Breast cancer expression profile data GSE27567 was downloaded from the Gene Expression Omnibus (GEO) database, and breast cancer-related genes were extracted from databases, including Cancer-Resource and Online Mendelian Inheritance In Man (OMIM). Next, h17 transcription factor data were obtained from the University of California, Santa Cruz. Database for Annotation, Visualization, and Integrated Discovery (DAVID)-enrichment analysis was applied and gene-regulatory networks were constructed by double-two-way t-tests in 3 states, including normal, benign, and malignant. Furthermore, network topological properties were compared between 2 states, and breast cancer-related bub genes were ranked according to their different degrees between each of the two states. A total of 2380 breast cancer-related genes and 215 transcription factors were screened by exploring databases; the genes were mainly enriched in their functions, such as cell apoptosis and proliferation, and pathways, such as p53 signaling and apoptosis, which were related with carcinogenesis. In addition, gene-regulatory networks in the 3 conditions were constructed. By comparing their network topological properties, we found that there is a larger transition of differences between malignant and benign breast cancer. Moreover, 8 hub genes (YBX1, ZFP36, YY1, XRCC5, XRCC4, ZFHX3, ZMAT3, and XPC) were identified in the top 10 genes ranked by different degrees. Through comparative analysis of gene-regulation networks, we identified the link between related genes and the pathogenesis of breast cancer. However, further experiments are needed to confirm our results.

Zhang YW, Zhao XX, Tan C, et al.
Epstein-Barr virus latent membrane protein 2A suppresses the expression of HER2 via a pathway involving TWIST and YB-1 in Epstein-Barr virus-associated gastric carcinomas.
Oncotarget. 2015; 6(1):207-20 [PubMed] Article available free on PMC after 30/09/2015 Related Publications
To explore HER2 expression in Epstein-Barr virus-associated gastric carcinoma (EBVaGC) and the possible mechanisms causing down-regulation of HER2 expression in EBVaGC, we first evaluated HER2 and LMP2A expression on a clinicopathological-features matched cohort including 78 EBVaGC and 216 EBV-negative gastric carcinoma (EBVnGC) cases by immunohistochemistry. Cases with high HER2 expression in EBVaGC were significantly less than in EBVnGC (5.1% versus 23.7%; p<0.001), and none of the 34 LMP2A+ EBVaGC showed high HER2 expression. Further, overexpressing LMP2A in EBV-negative SGC7901 cells significantly decreased HER2, TWIST and YB-1 mRNA by 36.1%±8.1%, 87.6%±14.0% and 83.8%±5.7%, and protein by 44%, 57% and 49%, respectively. Additionally, the nucleus/cytoplasm ratios of TWIST and YB-1 were also decreased by 85% and 80%, respectively. Silencing LMP2A by siRNA in EBV-positive SNU719 cells for 48 h significantly increased HER2, TWIST and YB-1 mRNA to 276.7%±14.6%, 1284.8%±38.2% and 332.0%±15.5% and protein to 212%, 457% and 232%, respectively. The nucleus/cytoplasm ratios of TWIST and YB-1 were up-regulated by 4.00- and 3.57-fold, respectively, following LMP2A down-regulation. Moreover, LMP2A+/HER2low EBVaGC cases presented the best overall survival compared with LMP2A-/HER2low and LMP2A-/HER2high cases (p=0.003, log-rank test). These results suggest that LMP2A may suppress the HER2 expression through the TWIST/YB-1 axis in EBVaGC.

Liu D, Zhao ZG, Jiao ZL, Li HJ
Identifying differential expression genes and single nucleotide variations using RNA-seq in metastatic melanoma.
Genet Mol Res. 2014; 13(4):8153-62 [PubMed] Related Publications
Melanoma is a malignant tumor and one of the most frequent metastatic cancers. This study was conducted to identify differential expression genes (DEGs) and single nucleotide variations (SNVs) in metastatic melanoma. We analyzed microarray data of GSE23056 downloaded from the Gene Expression Omnibus, including two normal samples (skinN1 and skinN2) and 2 metastatic melanoma samples (skinT and lymphT). We not only compared DEGs in metastatic melanoma samples with normal samples (lymphT_skinN and skinT_skinN), but also compared DEGs between two metastatic melanoma types (lymphT_skinT). SNVs were identified by using Burrows-Wheeler Aligner and Cufflinks in metastatic melanoma samples using RNA-seq. Sequence Alignment/Map tools and the ANNOVAR software were used to analyze and annotate SNVs. We identified 18 significantly common DEGs in lymphT_skinN and skinT_skinN and one common gene, YBX1, in lymphT_skinN, skinT_skinN, and lymphT_skinT. We identified 49,534, 48,118, 63,812, and 33,096 SNVs in skinN1, skinN2, skinT, and lymphT, respectively. Twenty-nine SNVs were located in exonic regions of two DEGs, HLA-B and TSPAN10. SNVs that exist only in tumors were located in MARVELD1, SLC16A3, and VAV3. The DEGs screened in our study are potential biomarkers for metastatic melanoma therapy.

Yan XB, Zhu QC, Chen HQ, et al.
Knockdown of Y‑box‑binding protein‑1 inhibits the malignant progression of HT‑29 colorectal adenocarcinoma cells by reversing epithelial‑mesenchymal transition.
Mol Med Rep. 2014; 10(5):2720-8 [PubMed] Related Publications
Y‑box binding protein‑1 (YB‑1) has been identified as an oncoprotein in various malignancies. The aim of this study was to investigate the biological role of YB‑1 and its association with epithelial‑to‑mesenchymal transition (EMT) in colorectal cancer (CRC). The expression of YB‑1 and three EMT‑related proteins (E‑cadherin, N‑cadherin and vimentin) was analyzed in 80 CRC and matched normal tissue samples, by immunohistochemistry. The results indicated that the expression of YB‑1 was higher in CRC tissue samples than that in matched normal controls and was significantly correlated with tumor differentiation, tumor invasion, lymph node metastasis and distant metastases. Furthermore, analysis showed that YB‑1 expression was negatively correlated with E‑cadherin and positively correlated with N‑cadherin and vimentin expression. In vitro assays showed that knockdown of YB‑1 inhibited the proliferation, apoptosis resistance, invasion and migration of the HT‑29 CRC cell line. Of note, following knockdown of YB‑1, E‑cadherin expression was elevated whereas N‑cadherin and vimentin expression was reduced. Taken together, these results suggest that YB‑1 promotes the malignant progression of CRC in part through the induction of EMT, and YB‑1 may therefore be a potential novel target for CRC treatment.

Jung K, Wu F, Wang P, et al.
YB-1 regulates Sox2 to coordinately sustain stemness and tumorigenic properties in a phenotypically distinct subset of breast cancer cells.
BMC Cancer. 2014; 14:328 [PubMed] Article available free on PMC after 30/09/2015 Related Publications
BACKGROUND: Sox2, a transcription factor and an embryonic stem cell marker, has been implicated in the pathogenesis of breast cancer (BC). YB-1 is another transcription factor that has been shown to promote stemness in BC cells.
METHODS: Western blotting, quantitative PCR, and siRNAs were used to query the regulatory relationships between YB-1, Sox2, and their downstream targets. Chromatin immunoprecipitation was used to detect YB-1 interactions at the Sox2 promoter. Mammosphere and soft agar assays were used to assess the phenotypic consequences of YB-1 knockdown.
RESULTS: Here, we report that YB-1 regulates Sox2. YB-1 was found to bind to the SOX2 promoter and down-regulate its expression in MCF7 and ZR751. The regulatory interaction between YB-1 and Sox2 was drastically different between the two phenotypically distinct cell subsets, purified based on their differential response to a Sox2 reporter. They are referred to as the reporter unresponsive (RU) cells and the reporter responsive (RR) cells. Upon siRNA knockdown of YB-1, RU cells showed an increase in Sox2 expression but no change in Sox2 reporter activity; in contrast, RR cells exhibited increased expression and reporter activity of Sox2. Correlating with these findings, YB-1 knockdown induced a differential response in the expression of genes known to be regulated by both Sox2 and YB-1 (e.g. CCND1 and ITGA6). For instance, in response to YB-1 knockdown, CCND1 and ITGA6 expression were decreased or unchanged in RU cells but paradoxically increased in RR cells. Compared to RU cells, RR cells were significantly more resistant to the suppression of mammosphere formation due to YB-1 knockdown. Importantly, mammospheres derived from parental MCF7 cells treated with YB-1 siRNA knockdown exhibited higher expression levels of SOX2 and its downstream targets.
CONCLUSIONS: To conclude, in a subset of BC cells, namely RR cells, YB-1 regulates Sox2 to coordinately maintain stemness and tumorigenic properties.

Harada M, Kotake Y, Ohhata T, et al.
YB-1 promotes transcription of cyclin D1 in human non-small-cell lung cancers.
Genes Cells. 2014; 19(6):504-16 [PubMed] Related Publications
Cyclin D1, an oncogenic G1 cyclin, and YB-1, a transcription factor involved in cell growth, are both over-expressed in several human cancers. In human lung cancer, the functional association between YB-1 and cyclin D1 has never been elucidated. In this study, we show YB-1 is involved in the transcription of cyclin D1 in human lung cancer. Depletion of endogenous YB-1 by siRNA inhibited progression of G1 phase and down-regulated both the protein and mRNA levels of cyclin D1 in human lung cancer cells. Forced over-expression of YB-1 with a cyclin D1 reporter plasmid increased luciferase activity, and ChIP assay results showed YB-1 bound to the cyclin D1 promoter. Moreover, the amount of YB-1 mRNA positively correlated with cyclin D1 mRNA levels in clinical non-small-cell lung cancer (NSCLC) specimens. Immunohistochemical analysis also indicated YB-1 expression correlated with cyclin D1 expression in NSCLC specimens. In addition, most of the cases expressing both cyclin D1 and CDC6, another molecule controlled by YB-1, had co-existing YB-1 over-expression. Together, our results suggest that aberrant expression of both cyclin D1 and CDC6 by YB-1 over-expression may collaboratively participate in lung carcinogenesis.

Shiota M, Itsumi M, Yokomizo A, et al.
Targeting ribosomal S6 kinases/Y-box binding protein-1 signaling improves cellular sensitivity to taxane in prostate cancer.
Prostate. 2014; 74(8):829-38 [PubMed] Related Publications
BACKGROUND: Taxanes are the only cytotoxic chemotherapeutic agents proved to prolong the survival in patients with castration-resistant prostate cancer. However, because of intrinsic and acquired resistances to taxanes, their therapeutical efficiencies are modest, bringing only a few months of survival benefit. Y-box binding protein-1 (YB-1) promotes cancer cell resistance to various anticancer treatments, including taxanes. Here, we aimed to elucidate the mechanism of taxane resistance by YB-1 and examined overcoming resistance by targeting YB-1 signaling.
METHODS: Gene and protein expression levels were evaluated by quantitative real-time polymerase chain reaction and Western blot analysis, respectively. We evaluated the sensitivity of prostate cancer cells to taxanes using cytotoxicity assays.
RESULTS: Natural taxane paclitaxel from Taxus brevifolia activated the Raf-1/extracellular signal-regulated kinase (ERK) pathway, leading to an activation of ribosomal S6 kinases (RSK)/YB-1 signaling. Activated Raf-1/ERK pathway was blunted by YB-1 knockdown in prostate cancer cells, indicating regulation between Raf-1/ERK signaling and YB-1. In addition, ERK or RSK was activated in taxane-resistant prostate cancer cells, resulting in YB-1 activation. YB-1 knockdown as well as RSK inhibition using RSK-specific siRNA or the small molecule inhibitor SL0101 successfully blocked activation of YB-1, leading to suppression of prostate cancer growth and sensitization to paclitaxel.
CONCLUSIONS: Taken together, these findings indicate that RSK/YB-1 signaling contributes to taxane resistance, and implicate the therapeutics targeting RSK/YB-1 signaling such as RSK inhibitor as a promising novel therapy against prostate cancer, especially in combination with taxane.

Fitzgerald KA, Evans JC, McCarthy J, et al.
The role of transcription factors in prostate cancer and potential for future RNA interference therapy.
Expert Opin Ther Targets. 2014; 18(6):633-49 [PubMed] Related Publications
INTRODUCTION: Prostate cancer is a leading cause of cancer-related death in men and current treatments offer only a modest survival benefit in advanced stages of the disease. RNA interference (RNAi) is a therapeutic option that has received great attention in recent years with the potential to treat a variety of disorders, including prostate cancer. Transcription factors are cellular proteins that can up-regulate or down-regulate the transcription of genes and offer promising therapeutic targets.
AREAS COVERED: This review will focus on transcription factors that have been identified as key molecules in drug resistance, disease progression and metastases in prostate cancer, which may offer potential as therapeutic targets for RNAi in the future.
EXPERT OPINION: By identifying therapeutically viable transcription factor targets in prostate cancer, it is hoped that treatment strategies using RNAi will augment the effect of current chemotherapy regimens, slow disease progression and reduce metastases in prostate cancer, resulting in disease regression.

Davies AH, Reipas KM, Pambid MR, et al.
YB-1 transforms human mammary epithelial cells through chromatin remodeling leading to the development of basal-like breast cancer.
Stem Cells. 2014; 32(6):1437-50 [PubMed] Article available free on PMC after 30/09/2015 Related Publications
There is growing evidence that cancer-initiation could result from epigenetic changes. Y-box binding protein-1 (YB-1) is a transcription/translation factor that promotes the formation of tumors in transgenic mice; however, the underlying molecular events are not understood. To explore this in a human model system, YB-1 was expressed in mammary epithelial cells under the control of a tetracycline-inducible promoter. The induction of YB-1 promoted phenotypes associated with malignancy in three-dimensional breast acini cultures. This was attributed to YB-1 enhancing the expression and activity of the histone acetyltransferase p300 leading to chromatin remodeling. Specifically, this relaxation of chromatin allowed YB-1 to bind to the BMI1 promoter. The induction of BMI1 engaged the Polycomb complex resulting in histone H2A ubiquitylation and repression of the CDKN2A locus. These events manifested functionally as enhanced self-renewal capacity that occurred in a BMI1-dependent manner. Conversely, p300 inhibition with anacardic acid prevented YB-1 from binding to the BMI1 promoter and thereby subverted self-renewal. Despite these early changes, full malignant transformation was not achieved until RSK2 became overexpressed concomitant with elevated human telomerase reverse transcriptase (hTERT) activity. The YB-1/RSK2/hTERT expressing cells formed tumors in mice that were molecularly subtyped as basal-like breast cancer. We conclude that YB-1 cooperates with p300 to allow BMI1 to over-ride p16(INK4a) -mediated cell cycle arrest enabling self-renewal and the development of aggressive breast tumors.

Tamim S, Vo DT, Uren PJ, et al.
Genomic analyses reveal broad impact of miR-137 on genes associated with malignant transformation and neuronal differentiation in glioblastoma cells.
PLoS One. 2014; 9(1):e85591 [PubMed] Article available free on PMC after 30/09/2015 Related Publications
miR-137 plays critical roles in the nervous system and tumor development; an increase in its expression is required for neuronal differentiation while its reduction is implicated in gliomagenesis. To evaluate the potential of miR-137 in glioblastoma therapy, we conducted genome-wide target mapping in glioblastoma cells by measuring the level of association between PABP and mRNAs in cells transfected with miR-137 mimics vs. controls via RIPSeq. Impact on mRNA levels was also measured by RNASeq. By combining the results of both experimental approaches, 1468 genes were found to be negatively impacted by miR-137--among them, 595 (40%) contain miR-137 predicted sites. The most relevant targets include oncogenic proteins and key players in neurogenesis like c-KIT, YBX1, AKT2, CDC42, CDK6 and TGFβ2. Interestingly, we observed that several identified miR-137 targets are also predicted to be regulated by miR-124, miR-128 and miR-7, which are equally implicated in neuronal differentiation and gliomagenesis. We suggest that the concomitant increase of these four miRNAs in neuronal stem cells or their repression in tumor cells could produce a robust regulatory effect with major consequences to neuronal differentiation and tumorigenesis.

Győrffy B, Bottai G, Lehmann-Che J, et al.
TP53 mutation-correlated genes predict the risk of tumor relapse and identify MPS1 as a potential therapeutic kinase in TP53-mutated breast cancers.
Mol Oncol. 2014; 8(3):508-19 [PubMed] Related Publications
Breast cancers (BC) carry a complex set of gene mutations that can influence their gene expression and clinical behavior. We aimed to identify genes driven by the TP53 mutation status and assess their clinical relevance in estrogen receptor (ER)-positive and ER-negative BC, and their potential as targets for patients with TP53 mutated tumors. Separate ROC analyses of each gene expression according to TP53 mutation status were performed. The prognostic value of genes with the highest AUC were assessed in a large dataset of untreated, and neoadjuvant chemotherapy treated patients. The mitotic checkpoint gene MPS1 was the most significant gene correlated with TP53 status, and the most significant prognostic marker in all ER-positive BC datasets. MPS1 retained its prognostic value independently from the type of treatment administered. The biological functions of MPS1 were investigated in different BC cell lines. We also assessed the effects of a potent small molecule inhibitor of MPS1, SP600125, alone and in combination with chemotherapy. Consistent with the gene expression profiling and siRNA assays, the inhibition of MPS1 by SP600125 led to a reduction in cell viability and a significant increase in cell death, selectively in TP53-mutated BC cells. Furthermore, the chemical inhibition of MPS1 sensitized BC cells to conventional chemotherapy, particularly taxanes. Our results collectively demonstrate that TP53-correlated kinase MPS1, is a potential therapeutic target in BC patients with TP53 mutated tumors, and that SP600125 warrant further development in future clinical trials.

Kosnopfel C, Sinnberg T, Schittek B
Y-box binding protein 1--a prognostic marker and target in tumour therapy.
Eur J Cell Biol. 2014 Jan-Feb; 93(1-2):61-70 [PubMed] Related Publications
Y-box binding protein 1 (YB-1) is a multifunctional protein involved in various cellular processes including both transcriptional and translational regulation of target gene expression. Significantly increased YB-1 levels have been reported in a number of human malignancies and shown to be associated with poor prognosis and disease recurrence. Indeed, YB-1 can act as a versatile oncoprotein playing an important role in tumour cell proliferation and progression. Consequently, YB-1 not only proves to be a good prognostic tumour marker, but also may be a promising emerging molecular target for the development of new therapeutical strategies. In this review, we discuss both the role of YB-1 in cancer and specifically in malignant melanoma as well as possible translations into the clinics derived thereof.

Zhang H, Cheng S, Zhang M, et al.
Prostaglandin E2 promotes hepatocellular carcinoma cell invasion through upregulation of YB-1 protein expression.
Int J Oncol. 2014; 44(3):769-80 [PubMed] Related Publications
Prostaglandin E2 (PGE2) has been implicated in hepatocellular carcinoma cell invasion. Recently, it was reported that Y box-binding protein 1 (YB-1) is closely correlated with malignancy. This study was designed to examine the mechanisms by which PGE2 increases YB-1 expression and promotes HCC cell invasion. PGE2 greatly enhanced HCC cell invasion through upregulation of the YB-1 protein, and the EP1 receptor is mainly responsible for this regulation. Src and EGFR were both activated by PGE2, which in turn increased the phosphorylation levels of p44/42 MAPK. Src, EGFR and p44/42 MAPK were all involved in PGE2-induced YB-1 expression. Chemical inhibitors and RNAi analysis all confirmed the role of mTOR complex 1 in YB-1 expression induced by PGE2. Furthermore, YB-1 was able to regulate the expression of a series of EMT-associated genes, which indicated that YB-1 could have the potential to control the epithelial-mesenchymal transition process in HCC cells. These findings reveal that PGE2 upregulated YB-1 expression through the EP1/Src/EGFR/p44/42 MAPK/mTOR pathway, which greatly enhanced HCC cell invasion. This study for the first time describes the mechanisms through which PGE2 regulates YB-1 expression and promotes HCC cell invasion.

Wu K, Chen K, Wang C, et al.
Cell fate factor DACH1 represses YB-1-mediated oncogenic transcription and translation.
Cancer Res. 2014; 74(3):829-39 [PubMed] Article available free on PMC after 30/09/2015 Related Publications
The epithelial-mesenchymal transition (EMT) enhances cellular invasiveness and confers tumor cells with cancer stem cell-like characteristics, through transcriptional and translational mechanisms. The mechanisms maintaining transcriptional and translational repression of EMT and cellular invasion are poorly understood. Herein, the cell fate determination factor Dachshund (DACH1), suppressed EMT via repression of cytoplasmic translational induction of Snail by inactivating the Y box-binding protein (YB-1). In the nucleus, DACH1 antagonized YB-1-mediated oncogenic transcriptional modules governing cell invasion. DACH1 blocked YB-1-induced mammary tumor growth and EMT in mice. In basal-like breast cancer, the reduced expression of DACH1 and increased YB-1 correlated with poor metastasis-free survival. The loss of DACH1 suppression of both cytoplasmic translational and nuclear transcriptional events governing EMT and tumor invasion may contribute to poor prognosis in basal-like forms of breast cancer, a relatively aggressive disease subtype.

Liu X, Su L, Liu X
Loss of CDH1 up-regulates epidermal growth factor receptor via phosphorylation of YBX1 in non-small cell lung cancer cells.
FEBS Lett. 2013; 587(24):3995-4000 [PubMed] Related Publications
Although loss of CDH1 promotes cancer metastasis by disrupting cell-cell adhesion and inducing transcriptional changes, the functional pathways involved in the loss of CDH1 affecting EGFR expression in lung cancer cells still remain largely unknown. In this study, we report that down-regulation of CDH1 promoted EGFR transcription through activation of YBX1. Furthermore, knockdown of CDH1 activated the AKT signaling pathway, and inhibition of AKT suppressed the phosphorylation of YBX1 and the up-regulation of EGFR induced by CDH1 loss. These data demonstrate that loss of CDH1 induces EGFR expression via phospho-YBX1, which is activated through the AKT signaling pathway.

Yuan L, Xiao Y, Zhou Q, et al.
Proteomic analysis reveals that MAEL, a component of nuage, interacts with stress granule proteins in cancer cells.
Oncol Rep. 2014; 31(1):342-50 [PubMed] Related Publications
The Maelstrom (MAEL) gene is a cancer-testis (or cancer-germline) gene, which is predominantly expressed in germline cells under normal conditions, but is aberrantly expressed in a range of human cancer cells. In germline cells, MAEL is found predominantly in the nuage, where it plays an essential role in piRNA biogenesis and piRNA-mediated silencing of transposons. However, the role of MAEL in cancer has not been elucidated. We performed immunoprecipitation and Nano-LC-MS/MS analysis to investigate the interactome of MAEL, and identified 14 components of stress granules (SGs) as potential binding partners of MAEL in MDA-MB-231 human breast cancer and SW480 colorectal cancer cells. The interactions between MAEL and 8 of these SG components (PABPC1, YBX1, KHSRP, SYNCRIP, DDX39, ELAV1, EIF4A1 and EIF3F) were confirmed by anti-tag immunoprecipitation. Immunofluorescence analysis showed that MAEL co-localizes with the SG marker PABPC1 in SGs during oxidative stress. Nuages and SGs are the cytoplasmic RNA granules of germline cells and stressed somatic cells, respectively, and both serve as a platform for small RNA-mediated gene silencing. It is, therefore, suggested that MAEL may be involved in miRNA-mediated gene silencing in SGs, as it does in the nuage. This finding should be valuable toward understanding the function of MAEL in carcinogenesis.

Mylona E, Melissaris S, Giannopoulou I, et al.
Y-box-binding protein 1 (YB1) in breast carcinomas: relation to aggressive tumor phenotype and identification of patients at high risk for relapse.
Eur J Surg Oncol. 2014; 40(3):289-96 [PubMed] Related Publications
AIMS: To investigate the expression pattern of Y-box-binding protein 1 (YB1) in breast carcinomas, its clinicopathological and prognostic value, and its association with the breast cancer stem cell phenotype [CD44(+)/CD24(-/low)].
METHODS AND RESULTS: Immunohistochemistry was performed on 225 paraffin embedded specimens of invasive breast carcinomas to detect the expression of the proteins YB1, ER, PR, HER2, p53, Ki67, bcl-2, CD44 and CD24. YB1 protein was detected in the nuclei, the cytoplasm and the stroma of the tumor cells. Cytoplasmic YB1 was detected more often in carcinomas of ductal type (p = 0.002), of higher nuclear grade (p < 0.001), with lack of ER expression (p = 0.002), positive expression of p53 and Ki67 (p = 0.002 and p = 022, respectively), and with present CD44(+)/CD24(-/low) breast cancer stem cells (p = 0.001), while its association with bcl-2 was found to be inverse (p = 0.042). Nuclear YB1 was found to exert unfavorable impact on the disease-free survival of the unselected patients (p = 0.05) and the patients having been subjected to adjuvant chemotherapy and radiotherapy (p = 0.036 and p = 0.05, respectively).
CONCLUSIONS: Cytoplasmic YB1 is associated with an aggressive and "stem cell-like" tumor phenotype, while nuclear localization discriminates patients at high risk for recurrence, especially those who are subjected to chemo- and radiotherapy.

Imada K, Shiota M, Kohashi K, et al.
Mutual regulation between Raf/MEK/ERK signaling and Y-box-binding protein-1 promotes prostate cancer progression.
Clin Cancer Res. 2013; 19(17):4638-50 [PubMed] Related Publications
PURPOSE: Y-box-binding protein-1 (YB-1) is known to conduct various functions related to cell proliferation, anti-apoptosis, epithelial-mesenchymal transition, and castration resistance in prostate cancer. However, it is still unknown how YB-1 affects cancer biology, especially its correlations with the mitogen-activated protein kinase (MAPK) signaling pathway. Therefore, we aimed to examine the interaction between YB-1 and the MAPK pathway in prostate cancer.
EXPERIMENTAL DESIGN: Quantitative real-time PCR, Western blotting, and co-immunoprecipitation assay were conducted in prostate cancer cells. YB-1, phosphorylated YB-1 (p-YB-1), and ERK2 protein expressions in 165 clinical specimens of prostate cancer were investigated by immunohistochemistry. YB-1, p-YB-1, and ERK2 nuclear expressions were compared with clinicopathologic characteristics and patient prognoses.
RESULTS: EGF upregulated p-YB-1, whereas MEK inhibitor (U0126, PD98059) decreased p-YB-1. Inversely, silencing of YB-1 using siRNA decreased the expression of ERK2 and phosphorylated MEK, ERK1/2, and RSK. Furthermore, YB-1 interacted with ERK2 and Raf-1 and regulated their expressions, through the proteasomal pathway. Immunohistochemical staining showed a significant correlation among the nuclear expressions of YB-1, p-YB-1, and ERK2. The Cox proportional hazards model revealed that high ERK2 expression was an independent prognostic factor [HR, 7.947; 95% confidence interval (CI), 3.527-20.508; P<0.0001].
CONCLUSION: We revealed the functional relationship between YB-1 and MAPK signaling and its biochemical relevance to the progression of prostate cancer. In addition, ERK2 expression was an independent prognostic factor. These findings suggest that both the ERK pathway and YB-1 may be promising molecular targets for prostate cancer diagnosis and therapeutics.

Matsumoto H, Yamamoto Y, Shiota M, et al.
Cotargeting Androgen Receptor and Clusterin Delays Castrate-Resistant Prostate Cancer Progression by Inhibiting Adaptive Stress Response and AR Stability.
Cancer Res. 2013; 73(16):5206-17 [PubMed] Related Publications
Although androgen receptor (AR) pathway inhibitors prolong survival in castrate-resistant prostate cancer (CRPC), resistance rapidly develops and is often associated with increased stress-activated molecular chaperones like clusterin (CLU) and continued AR signaling. Because adaptive pathways activated by treatment facilitate development of acquired resistance, cotargeting the stress response, activated by AR inhibition and mediated through CLU, may create conditional lethality and improve outcomes. Here, we report that CLU is induced by AR antagonism and silencing using MDV3100 and antisense, respectively, to become highly expressed in castrate- and MDV3100-resistant tumors and cell lines. CLU, as well as AKT and mitogen-activated protein kinase (MAPK) signalosomes, increase in response to MDV3100-induced stress. Mechanistically, this stress response is coordinated by a feed-forward loop involving p90rsk (RPS6KA)-mediated phosphoactivation of YB-1 with subsequent induction of CLU. CLU inhibition repressed MDV3100-induced activation of AKT and MAPK pathways. In addition, when combined with MDV3100, CLU knockdown accelerated AR degradation and repressed AR transcriptional activity through mechanisms involving decreased YB-1-regulated expression of the AR cochaperone, FKBP52. Cotargeting the AR (with MDV3100) and CLU (with OGX-011) synergistically enhanced apoptotic rates over that seen with MDV3100 or OGX-011 monotherapy and delayed CRPC LNCaP tumor and prostate-specific antigen (PSA) progression in vivo. These data indicate that cotargeting adaptive stress pathways activated by AR pathway inhibitors, and mediated through CLU, creates conditional lethality and provides mechanistic and preclinical proof-of-principle to guide biologically rational combinatorial clinical trial design.

Shiota M, Kashiwagi E, Yokomizo A, et al.
Interaction between docetaxel resistance and castration resistance in prostate cancer: implications of Twist1, YB-1, and androgen receptor.
Prostate. 2013; 73(12):1336-44 [PubMed] Related Publications
BACKGROUND: Taxanes, including docetaxel, are currently the only cytotoxic chemotherapeutic agents proven to confer survival benefit in patients with castration-resistant prostate cancer (CRPC). However, the merits of taxanes remain modest, and efforts are needed to improve their therapeutic efficacy.
METHODS: We evaluated the sensitivity of prostate cancer cells to various agents using cytotoxicity assays. Gene and protein expression levels were evaluated by quantitative real-time polymerase chain reaction and Western blotting analysis, respectively.
RESULTS: Hydrogen peroxide-resistant and castration-resistant cells that overexpressed Twist1 and Y-box binding protein-1 (YB-1) were cross-resistant to cytotoxic agents, including docetaxel. Twist1 regulated YB-1 expression in prostate cancer cells, supported by the induction of Twist1 and YB-1 by transforming-growth factor-β, which is critical for taxane resistance. Twist1 and/or YB-1 were activated in docetaxel-resistant prostate cancer cells, and YB-1 was activated by docetaxel treatment. Conversely, Twist1 and YB-1 knockdown sensitized prostate cancer cells to cytotoxic agents, including docetaxel. In addition, androgen receptor (AR) knockdown increased cellular sensitivity to docetaxel, though AR expression in docetaxel-resistant LNCaP cells was paradoxically lower than in parental cells. Intriguingly, androgen deprivation treatment was more effective in docetaxel-resistant LNCaP cells compared with parental cells.
CONCLUSIONS: Twist1/YB-1 and AR signaling promote docetaxel resistance in CRPC cells. However, docetaxel-resistant cells were collaterally sensitive to androgen deprivation because of down-regulation of AR expression, suggesting that the therapeutic effect of initial taxane treatment in hormone-naïve prostate cancer may be superior to that of salvage taxane treatment in CRPC.

Popp SL, Joffroy C, Stope MB, et al.
Antiestrogens suppress effects of transforming growth factor-β in breast cancer cells via the signaling axis estrogen receptor-α and Y-box Binding Protein-1.
Anticancer Res. 2013; 33(6):2473-80 [PubMed] Related Publications
BACKGROUND: Multifunctional Y-box Binding Protein-1 (YB1) is correlated with a poor outcome in breast cancer. We found YB1 expression to be regulated by antiestrogens commonly used in the hormonal therapy of breast cancer and known as activators of Transforming Growth Factor-β (TGFβ). Thus, a putative influence of YB1 on TGFβ signaling should be investigated.
MATERIALS AND METHODS: The effect of YB1 on TGFβ signaling was monitored by expression analysis and reporter gene assays in breast cancer cells overexpressing YB1 and treated with antiestrogens.
RESULTS: Antiestrogen-mediated inhibition of estrogen receptor-α led to a suppression of YB1 protein synthesis. On the other hand, YB1 was found to be an enhancer of TGFβ signaling.
CONCLUSION: High levels of YB1 expression lead to a stimulation of TGFβ pathways, thereby counteracting antihormonal breast cancer therapy and representing a putative resistance mechanism.

Iborra S, Hirschfeld M, Jaeger M, et al.
Alterations in expression pattern of splicing factors in epithelial ovarian cancer and its clinical impact.
Int J Gynecol Cancer. 2013; 23(6):990-6 [PubMed] Related Publications
OBJECTIVE: Alternative splicing represents an important nuclear mechanism in the posttranscriptional regulation of gene expression, which is frequently altered during tumorigenesis. Previously, we described marked changes in alternative splicing of the CD44 gene in ovarian and breast cancer as well as specific induction of distinct splicing factors during tumor development. The present study was focused on the expression profiles of different splicing factors, including classical serine-arginine (SR) proteins including ASF/SF2, hTra2β1, hTra2α, and Y-box-binding protein (YB-1) in physiological and malignant epithelial ovarian tissue to evaluate their expression pattern with regard to tumor development and disease progression.
MATERIALS AND METHODS: Expression levels of the different splicing factors were analyzed in physiological epithelial ovarian tissue samples, primary tumors, and metastatic samples of patients with a diagnosis of epithelial ovarian cancer using quantified reverse transcription polymerase chain reaction analysis. We examined more closely the splicing factor hTra2β1 using Western blot analysis and immunohistochemistry.
RESULTS: The analysis revealed a marked and specific induction of ASF/SF2, SRp20, hTra2β1, and YB-1 in primary tumors as well as in their metastatic sites. However, in our patient cohort, no induction was seen for the other investigated splicing factors SRp55, SRp40, and hTra2α.
CONCLUSIONS: Our results suggest a specific induction of distinct splicing factors in ovarian cancer tumorigenesis. The involvement of hTra2β1, YB-1, SRp20, and ASF/SF2 in exon recognition and alternative splicing may be important for gene regulation of alternatively spliced genes like CD44 with potential functional consequences in this tumor type leading to progression and metastasis.

Schmid R, Meyer K, Spang R, et al.
Melanoma inhibitory activity promotes melanoma development through activation of YBX1.
Pigment Cell Melanoma Res. 2013; 26(5):685-96 [PubMed] Related Publications
Melanoma inhibitory activity (MIA), a small soluble secreted protein, is functionally important for progression of malignant melanoma. We recently revealed that p54(nrb) acts as a mediator of MIA action. In this study, we characterize the transcriptional regulation of p54(nrb) by MIA to explain MIA's molecular action. We identified one highly conserved region in the p54(nrb) promoter that is necessary and sufficient for MIA-dependent activation. Functional promoter analysis identified the transcription factor YBX1 as the mediator of MIA activation of p54(nrb) transcription. We screened the genome for further potential MIA-regulated genes carrying the element in their promoter regions. Integrating our sequence data with expression data from human melanomas identified a list of 23 potential MIA-YBX1 targets in melanomas. In summary, we present for the first time effects of MIA on transcriptional regulation. Uncovering new potential downstream effectors working via activation of YBX1 supports the important role of MIA in melanoma.

Shushanov SS, Mar'ina LG, Kravtsova TA, et al.
Coexpression of two mRNA isoforms of insulin-like growth factor-1 gene and mRNA of YB-1 gene in patients with multiple myeloma.
Bull Exp Biol Med. 2013; 154(5):654-7 [PubMed] Related Publications
Coexpression of two mRNA isoforms for insulin-like growth factor-1 (IGF-1A and IGF-1B) and expression of YB-1 mRNA were analyzed in the bone marrow aspirates from 19 patients with multiple myeloma. It was shown that mRNA isoforms for IGF-1A and IGF-1B were mainly expressed in samples with hyperexpression of YB-1 mRNA, and, on the contrary, practically were not expressed (except sporadic cases) in samples with low level of YB-1 mRNA expression. Coexpression of mRNA isoforms for IGF-1A and IGF-1B were observed in 80% patients with multiple myeloma.

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