OCT4B1 down-regulates self-renewal genes in cancer cell lines

OCT4 is an important gene involved in stem cell (ESC, ASC and CSC) self-renewal and cell stemness states. The OCT4 gene encodes at least three variants, including OCT4A, B, and B1, each one has different biological activities. OCT4A acts as a silencing factor and downregulates cell differentiation. OCT4B is expressed in stem and somatic cells and does not play a role in cell stemness whereas OCT4B1 is expressed in stem cells, especially cancer stem cells, and has anti-apoptotic properties. The present study was carried out to investigate the relation between these variants and key genes in self-renewal pathways. Cancer cell lines from gastric adenocarcinoma (AGS), bladder tumor (5637), and brain tumor (132N1) were transfected by specific OCT4B1 siRNA using lipofection method and the gene was successfully suppressed in the test group after 48 hours. The expression of OCT4A, OCT4B, SOX2, NANOG and KLF4 genes were evaluated by qRT-PCR after this time. The results demonstrated that expression levels of OCT4A and stemness genes including SOX2, NANOG and KLF4 were decreased following OCT4B1 downregulation, while expression of OCT4B was increased. Our results suggest a direct relation between expression of OCT4B1 and genes that control self-renewal. The data suggests that in the presence of OCT4B1, stemness genes are expressed, while in its absence, these genes will be down-regulated, therefore, strategies that specifically target repression could be considered for future molecular cancer therapies.