SOX2 promotes tumorigenesis and increases the anti-apoptotic property of human prostate cancer cell

SRY-related HMG-box gene 2 (SOX2) is one of the key regulatory genes that maintain the pluripotency and self-renewal properties in embryonic stem cells. Here we used immunohistochemistry to analyze the expression of SOX2 in human prostate tissues and found it contributed to tumorigenesis and correlated with histologic grade and Gleason score. We further investigated SOX2's function in cell growth and apoptosis process by using a human prostate cancer cell line DU145 with SOX2 overexpression or down-regulation. Cell cycle assay revealed that SOX2 promoted cell growth and increased the percentage of cells in S phase. In vitro and in vivo xenograft experiments in NOD/SCID mice further demonstrated that SOX2 increased the apoptosis-resistant properties of DU145 cells with decreased function of store-operated Ca(2+) entry and reduced expression of Orai1 at both mRNA and protein levels, suggesting a potential mechanism that contributes to the anti-apoptotic property of SOX2. To our knowledge, this study is the first to investigate SOX2's function in tumorigenesis and apoptosis of human prostate cancer and to elucidate its regulatory effect on the activity of store-operated Ca(2+) channels. Our results support the concept that SOX2 has the potential to be a significant marker to evaluate the progression of prostate cancer and serve as a potentially useful target for prostate cancer therapy.