Y-box binding protein 1 augments sorafenib resistance via the PI3K/Akt signaling pathway in hepatocellular carcinoma

BACKGROUND Sorafenib is the first-line treatment for patients with advanced hepatocellular carcinoma(HCC).Y-box binding protein 1(YB-1)is closely correlated with tumors and drug resistance.However,the relationship between YB-1 and sorafenib resistance and the underlying mechanism in HCC remain unknown.AIM To explore the role and related mechanisms of YB-1 in mediating sorafenib resistance in HCC.METHODS The protein expression levels of YB-1 were assessed in human HCC tissues and adjacent nontumor tissues.Next,we constructed YB-1 overexpression and knockdown hepatocarcinoma cell lines with lentiviruses and stimulated these cell lines with different concentrations of sorafenib.Then,we detected the proliferation and apoptosis in these cells by terminal deoxynucleotidyl transferase dUTP nick end labeling,flow cytometry and Western blotting assays.We also constructed a xenograft tumor model to explore the effect of YB-1 on the efficacy of sorafenib in vivo.Moreover,we studied and verified the specific molecular mechanism of YB-1 mediating sorafenib resistance in hepatoma cells by digital gene expression sequencing(DGE-seq).RESULTS YB-1 protein levels were found to be higher in HCC tissues than in corresponding nontumor tissues.YB-1 suppressed the effect of sorafenib on cell proliferation and apoptosis.Consistently,the efficacy of sorafenib in vivo was enhanced after YB-1 was knocked down.Furthermore,KEGG pathway enrichment analysis of DGEseq demonstrated that the phosphoinositide-3-kinase(PI3K)/protein kinase B(Akt)signaling pathway was essential for the sorafenib resistance induced by YB-1.Subsequently,YB-1 interacted with two key proteins of the PI3K/Akt signaling pathway(Akt1 and PIK3R1)as shown by searching the BioGRID and HitPredict websites.Finally,YB-1 suppressed the inactivation of the PI3K/Akt signaling pathway induced by sorafenib,and the blockade of the PI3K/Akt signaling pathway by LY294002 mitigated YB-1-induced sorafenib resistance.CONCLUSION Overall,we concluded that YB-1 augments sorafenib resistance through the PI3K/Akt signaling pathway in HCC and suggest that YB-1 is a key drug resistance-related gene,which is of great significance for the application of sorafenib in advanced-stage HCC.

Serum Y-Box Binding Protein 1 (YBX-1) and Interleukin 6 (IL-6) Are Associated with Metastasis in Breast Cancer Patients

Objectives: The aim of this study was to assess the levels of Y-box binding protein 1 (YBX-1) and interleukin 6 (IL-6) in the sera of metastatic and non-metastatic breast cancer patients (BC), investigate their clinicopathological significance and to analyze their potential use as biomarkers of breast cancer metastasis. Methods: The study included ninety subjects sub-grouped equally into metastatic BC, non-metastatic BC and healthy volunteers. Serum YBX-1 and IL-6 were quantified using ELISA technique while CA 15-3 was quantified using IRMA kit. Clinical data were collected from patients’ records. Results: YBX-1 (p < 0.001), IL-6 (p < 0.001) and CA15-3 (p = 0.017, 0.001) were significantly elevated in metastatic and non-metastatic BC patients compared to healthy controls, however, only YBX-1 (p 0.001) showed a significant difference with cancer metastasis. Generally, YBX-1 and IL-6 were correlated with worse histological grade and late clinical stage in breast cancer patients and they were also associated with axillary lymph nodes involvement and positive vascular invasion in metastatic BC patients. Serum YBX-1 and IL-6 levels were positively correlated to each other (rs = 0.615, p < 0.001) and they showed high sensitivity and specificity compared to CA 15-3 (p < 0.001 and p = 0.004 for YBX-1 and IL-6 respectively) for predicting cancer metastasis. Conclusions: Serum YBX-1 and IL-6 are potential biomarkers of breast cancer patients with significant correlation with bad clinicopathological characteristics. Serum YBX-1 and IL-6 have superior sensitivity and specificity compared to CA15-3 and can serve as potential follow up and prognostic markers.

Effect of TRAF6 gene silencing on hepatocellular carcinoma cell line SMCC7721 and its possible mechanism

Objective:To explore the effect of TRAF6 gene silencing on the function of hepatocellular carcinoma SMCC7721 and its possible mechanism.Method:Cell lines were constructed by cell transfection technology and verified by quantitative real-time PCR.Cell functional changes were observed by CCK8 method,Transwell test and Method of EdU.Western blotting was used to explore the possible mechanism of action.Result:TRAF6 RNA was abnormally up-regulated in HCC,and TRAF6 levels were detected in both HCC cell lines and L02 cells.SMCC7721 was selected as TRAF6 high expression cell.The results of CCK8 assay and EdU method showed that the decrease of TRAF6 expression significantly inhibited the proliferation of SMCC7721 cells.The results of CCK8 assay and EdU method showed that the decrease of TRAF6 expression significantly inhibited the proliferation of SMCC7721 cells.Overexpression of TRAF6 in TRAF6 knockdown cells can restore and enhance cell proliferation.Transwell assay confirmed that the invasiveness of SMCC 7721 cells treated with siRNA was significantly reduced.After treatment with LV-Rescue plasmid,the cell invasion was restored and enhanced.Western blotting showed that the protein levels of YB-1,Wnt,β-catenin,c-myc and Cyclin D1 were significantly down-regulated in siRNA group.On the contrary,the expression level of CYLD protein increased.Conclusion:As an important intracellular junctive protein in tumor cells,TRAF6 may improve the expression of pro-cancer factors C-myc and Cyclin D1 by modifying(ubiquitination)YB-1,thus improving the proliferation ability of cells.This process may be closely positively correlated with the Wnt/β-catenin pathway,and negatively correlated with the expression of CYLD protein.

YB-1对肿瘤发生的影响及其研究进展

YB-1(Y-box binding protein1,YB-1)是Y-盒蛋白家族成员之一,是能够特异性结合目的基因启动子和增强子内部Y-box序列(CTGATTGGCCAA)的一类转录因子,也是一类高度保守的顺式作用元件,普遍存在于原核和真核生物细胞中。YB-1在转录调节、翻译调控、mRNA选择性剪接、DNA的修复、细胞增殖和再生等过程中发挥多种重要的生物学功能。研究表明,YB-1蛋白在肿瘤的发生、演进、转移、肿瘤细胞耐药性、肿瘤治疗及预后中都发挥着极为重要的作用,已证实YB-1异常表达的肿瘤类型有前列腺癌、乳腺癌、肺癌、卵巢癌等多种肿瘤,并且在多种人类肿瘤中,YB-1在细胞核表达常常提示预后不良,YB-1蛋白在细胞核中的定位被认为是肿瘤疾病诊断的一种新的标志物,YB-1有望成为肿瘤防治的新的分子靶点。

YB-1 stabilizes HIV-1 genomic RNA and enhances viral production

HIV-1 utilizes cellular factors for effi cient replication.The viral RNA is different from cellular mRNAs in many aspects,and is prone to attacks by cellular RNA quality control systems.To establish effective infection,the virus has evolved multiple mechanisms to protect its RNA.Here,we show that expression of the Y-box binding protein 1(YB-1)enhanced the production of HIV-1.Downregulation of endogenous YB-1 in producer cells decreased viral production.YB-1 increased viral protein expression by stabilizing HIV-1 RNAs.The stem loop 2 in the HIV-1 RNA packaging signal was mapped to be the YB-1-responsive element.Taken together,these results indicate that YB-1 stabilizes HIV-1 genomic RNA and thereby enhances HIV-1 gene expression and viral production.

Expression of YB-1 enhances production of murine leukemia virus vectors by stabilizing genomic viral RNA

Murine leukemia virus(MLV)-based retroviral vectors is widely used for gene transfer and basic research,and production of high-titer retroviral vectors is very important.Here we report that expression of the Y-box binding protein 1(YB-1)enhanced the production of infectious MLV vectors.YB-1 specifically increased the stability of viral genomic RNA in virus-producing cells,and thus increasing viral RNA levels in both producer cells and virion particles.The viral element responsive to YB-1 was mapped to the repeat sequence(R region)in MLV genomic RNA.These results identified YB-1 as a MLV mRNA stabilizer,which can be used for improving production of MLV vectors.

Genomics of hepatitis B virus-related hepatocellular carcinoma and adjacent noncancerous tissues with cDNA microarray

Background Hepatocellular carcinoma （HCC） is a common primary cancer frequently associated with hepatitis B virus （HBV） infection. However, whether these identified genes are particularly associated with HBV-related HCC remains unknown. The aim of this study was to investigate the differential gene expression between HBV-related HCC tissues and adjacent noncancerous tissues. Methods cDNA microarray was used to detect the differential gene expression profile in the HBV-related HCC tissues and adjacent noncancerous tissues, and reverse transcription-polymerase chain reaction （RT-PCR） was performed to verify the differential expression of candidate genes obtained from cDNA microarray experiment. Results In this study, 1369 genes or expressed sequence tags （ESTs） including 121 genes or ESTs with at least two-fold expression alterations between cancerous and noncancerous tissues were identified. Special AT-rich sequence binding protein 1 （SATB-1） expression was positive in 73% （16/22） of cancerous tissues and negative （0/22） in all noncancerous tissues of HBV-related HCC patients. Transmembrane 4 superfamily member 1 （TM4SF-1） expression was positive in 86% （19/22） of cancerous tissues and negative （0/22） in all noncancerous tissues. Suppression of tumorigenicity 14 （ST-14） expression was positive in 73% （16/22） of noncancerous tissues in patients with HBV-related HCC and negative in all HCC tissues （0/22）. Conclusion This study provided the gene expression profile of HBV-related HCC and presented differential expression patterns of SATB-1, TM4SF-1 and ST-14 between cancerous and noncancerous tissues in patients with HBV-related HCC.