Expression of Oct4 in HCC and modulation to wnt/β-catenin and TGF-β signal pathways

Hepatocellular carcinoma (HCC) is considered as a disease of dysfunction of the stem cells. Studies on stem cells have demonstrated that Oct4 plays a pivotal role in embryo regulation. In order to understand the role of Oct4 in HCC and the relationship among Oct4 and wnt/beta-catenin and TGF-beta signal pathways, we have detected the expression of Oct4, Nanog, Sox2, STAT3 as well as the genes in wnt/beta-catenin, and TGF-beta families in HCC cell lines and in tumor specimens from HCC patients. The authors found that Oct4 was expressed in all of the four HCC cell lines and the tumor specimens from HCC patients. Some other genes were also expressed in them with different level including Nanog, Sox2, STAT3 and TCF3, wnt10b, beta-catenin, ELF, Smad3 and Smad4. The ability of the clone formation and migration of the HepG2 decreased after Oct4 was knockdowned. Silencing of Oct4 and TCF3 in HCC cell line HepG2 revealed that there were complicated relationships among Oct4, wnt/beta-catenin family and TGF-beta family genes. Knockdowning Oct4 reduced the expression of TGF-beta family genes ELF, Smad3, Smad4 and wnt/beta-catenin family genes, wnt10b, and beta-catenin but increased TCF3. In reverse, knockdowning TCF3 led to the increased expression of Oct4 and TGF-beta family genes. In conclusion, the expression of Oct4 in HCC may play an important role as in stem cell. Because Oct4 improves not only the function of wnt/beta-catenin, but also the TGF-beta signal pathways, the significance of its expression in HCC might be more complicated than we evinced before.