ZHX1 Is Down-regulated In Gastric Cancer And Regulates Cell Proliferation

Background and aims: Gastric cancer(GC)is one of the most common cancers in China,its incidence and mortality rates are both higher in all cancers.The carcinogenesis of GC is thought to be a complex multistep process that involves the inactivation of tumor suppressor genes ? the activation of oncogenes and epigenetic alteration.However,the underlying molecular mechanisms still be poorly understood.Moreover,it remains difficult to predict early GC using existing biomarkers.Therefore,achieving a better understanding of the mechanism will be helpful in detecting specific and sensitive biomarkers to predict early GC.As a novel transcription repressor ZHX1(Zinc-fingers and homeoboxes protein 1),wildly exists in the nucleus of various tissues and play the role of transcription inhibition.Recently many studies indicate that ZHX1 may involve in the regulation of cell proliferation,differentiation and metastasis.However,the role of ZHX1 in GC has not been explored.Therefore,the aim of this study is to investigate the expression of ZHX1 protein in GC tissues and its biological functions in GC cell.Methods: ZHX1 expression in GC tissues and paired non-tumor tissues was detected by immunohistochemical staining,and the association between ZHX1 protein expression and clinicopathological features were analyzed.We established a stable ZHX1 up-regulated NCI-N87 cell clone and a ZHX1 down-regulated SGC-7901 cell clone.Changes in ZHX1 levels were confirmed by qRT-PCR and Western blotting analysis.CCK-8 assay and Soft agar colony formation assay were employed to detect cell proliferation change.Transwell assay were used to test migration.Xenograft tumor models were generated to assess the inhibitory properties of ZHX1 in vivo.Flow cytometry was performed to analyze cell cycle and apoptosis.The markers of apoptosis and cell cycle were analyzed by Western blotting analysis.Results: Immunohistochemistry indicated that ZHX1 was down-regulated in GC tissues compared with pared non-tumor tissues.Lower expression of ZHX1 was correlated with larger tumor size(P=0.037),poorer differentiation(P=0.023),more advanced TMN stage(P=0.008)and deeper invasion depth(P=0.016).CCK-8 assay and Soft agar colony formation assay showed that ectopic expression of ZHX1 can inhibit cell growth;reduction of ZHX1 level had the opposite effects.Xenograft tumor models verified that ZHX1 could inhibit cell growth in vivo.ZHX1 induced cell apoptosis by Bcl2 downregulation and Bax and cleaved Caspase-3 upregulation.Morever,ZHX1 induced G1/S arrest by decreasing cyclin D1 and cyclin E expression.Conclusions: ZHX1 protein is down-regulated in GC tissues,and the loss of ZHX1 protein in GC tissues is correlation with adverse clinicopathological features.Moreover,ZHX1 inhibits GC cell growth through inducing apoptosis and cell cycle arrest.