A plausible anti-apoptotic role of up-regulated OCT4B1 in bladder tumors.

PURPOSE: To investigate and compare the expression of OCT4B1 between tumor and non-tumor bladder tissues. MATERIALS AND METHODS: We investigated the expression of OCT4B1 in 30 tumor and non-tumor surgical specimens of the bladder, using the TaqMan real-time polymerase chain reaction approach and by carefully designing primers and probes specific for the amplification of the variant. RESULTS: Most tumor and non-tumor samples of the bladder showed OCT4B1 expression, but its expression level was significantly higher in the tumors (P < .002). Moreover, the up-regulation of OCT4B1 was more significant in high-grade tumors compared to the low-grade ones (P < .05). We have also employed the RNA interference strategy to evaluate the functional role of OCT4B1 in a bladder cancer cell line, 5637. Suppression of OCT4B1 caused some changes in cell cycle distribution, and significantly elevated the rate of apoptosis in the cells. CONCLUSION: Our findings suggest that OCT4B1 plays a potential role in tumor initiation and/or progression of the bladder cancer. Additionally, OCT4B1 can be regarded as a new tumor marker for detection, classification, and treatment of the bladder cancer. However, more experimental studies are needed to replicate our findings.

OCT4B1, a novel spliced variant of OCT4, is highly expressed in gastric cancer and acts as an antiapoptotic factor.

The octamer-binding transcription factor 4 (OCT4) is involved in regulating pluripotency and self-renewal maintenance of embryonic stem cells. Recently, misexpression of OCT4 has been also reported in some adult stem as well as cancer cells; a finding which is still controversial. In addition to the previously described spliced variants of the gene (e.g., OCT4A and OCT4B), we have recently identified a novel variant of the gene, designated as OCT4-B1. In this study, we investigated a potential expression and function of OCT4B1 in a series of gastric cancer tissues and a gastric adenocarcinoma cell line, AGS. Using the Taqman real-time PCR approach, we have detected the expression of OCT4B1 in tumors with no or much lower expression in marginal samples of the same patients (p < 0.002). We have also analyzed the effects of OCT4B1 knock-down in AGS cell line treated with specific siRNA directed toward OCT4B1. Our data revealed that interfering with the expression of OCT4B1 caused profound changes in the morphology and cell cycle distribution of the cells. Furthermore, down-regulation of OCT4B1 significantly elevated the relative activity of caspase-3/caspase-7 and the rate of apoptosis in the cells (more than 30%). All together, our findings suggest that OCT4B1 has a potential role in tumorigenesis of gastric cancer and candidates the variant as a new tumor marker with potential value in diagnosis and treatment of gastric cancer.