Oct-4 Expression In Hepatocellular Carcinoma Tissue And Its Role In The Malignant Biological Behavior

BackgroundThe incidence of hepatocellular carcinoma is increasing worldwide year by year, but the prognosis of the patients with hepatocellular carcinoma is poor. Despite substantial progress in fundamental and clinical research, there is still lack of effective measure to improve the prognosis of these patients. Recurrence and metastasis after postoperation of those patients with HCC is the most important factor affecting the prognosis. So investigation of the invasive and metastasizing mechanism in hepatocellular carcinoma exists very important significance to improve the prognosis of hepatocellular carcinoma. Oct-4 is one of the nuclear transcription factors, expressed with embryonic stem cells, also shows high expression in a variety of tumors. Abnormally high expression of Oct-4 can increase the potential of stem cells into malignant cells. Epithelial-to-mesenchymal transition (EMT) exists in the progress of various cancers, including hepatocellular carcinoma. But whether the expression of Oct-4 is associated with the prognosis of patients with HCC and whether the expression of Oct-4 is related to the processes of EMT in HCC are still unclear.ObjectiveThe purpose of this study was to investigate the expression of Oct-4 in HCC tissues and the matched adjacent non-tumor tissues, to determine the correlation between expression of Oct-4 and the prognosis of patients with HCC, and to explore the role in the manner of HCC cells via in vitro experiments.Methods1 In the present study, IHC, western blot analysis, and qRT-PCR were performed to identify differentially OCT4 expression in HCC tissues and adjacent non-cancerous tissues.2 By qRT-PCR and Western-blot analysis, the expression of Oct-4 in four hepatocellular carcinoma cell lines (SMMC-7721, Huh-7, Bel-7404, HepG2 and liver cell liine HL-7702) were examined. Then the cell lines with Oct-4 high expressed were selected.3 In addition, the functions of Oct-4 on HCC progression were studied in vitro. Silencing of Oct-4 with siRNA was performed in HCC cell lines, and the impact on proliferation, migration, and the EMT markers of HCC was analyzed.Results1 Compared with the matched adjacent non-tumor tissues, Oct-4 is highly expressed in HCC tissues. In 44 cases of HCC tissues,35 cases present Oct-4 positive expressions (79.55%,35/44), while in 44 cases of the non-tumor tissues, Oct-4 positive expression is 47.72%(21/44). By chi-square test, Oct-4 expressions in HCC tissues were significantly higher than in adjacent non-tumor (P<0.01).2 The expression of Oct-4 mRNA correlated with tumor size, vascular invasion and TNM staging (P<0.05). Single factor analyses showed that Oct-4 genes associated with postoperative outcomes for patients with hepatocellular carcinoma. Multiple factors analysis presents that Oct-4 mRNA expression is not an independent prognosis factor.3 In liver cancer cell SMMC-7721 and HepG2, OCT4 has high expression of Oct-4, while in normal liver cell line HL-7702 the expression of Oct-4 was low.4 Cell counting kit showed that the decresed expression of Oct-4 can inhibit the proliferation of tumor cell lines, i.e. SMMC-7721 and HepG2. Transwell experiments show that transfected cells can obviously inhibit liver cancer cell migration and invasive ability. Western-blot experiments show the expression of Oct-4 was decreased after transfection, also EMT related expressions alterated with E-calcium up-regulation and vimentin and N-calcium down-regulation.Conclusions1 The high expression of Oct-4 mRNA and protein levels were found in the hepatocellular carcinoma tissue and human liver cancer cell lines. Its high expression corelate with larger tumor size, more vascular invasion and high TNM staging. It implies that Oct-4 may play an important role in the invasion, metastasis and prognosis of tumor.2 Single factor analyses show that Oct-4 genes associated with postoperative outcomes for patients with hepatocellular carcinoma. The patients with positive expression of Oct-4 had lower overall survival rates and disease-free survival rates. Multiple factors analyses present that Oct-4 mRNA expression is not an independent prognosis factors. Oct-4 mRNA expressions in hepatocellular carcinoma (HCC) can be taken as a reference index to imply the prognosis of postoperative patients with hepatocellular carcinoma.3 Our study established 2 strains of stabilizing hepatocellular carcinoma cells with the expression Oct-4 knocked down. Studies in vitro proved the Oct-4 genes promoted the proliferation, migration, invasion of cancer cells.4 The expression Oct-4 gene exists the positive relation with EMT markers, laying a foundation for molecular mechanisms of HCC. And it is helpful to find and block specific targets in the metastasis and recurrence of HCC.