SPAG9 is overexpressed in human prostate cancer and promotes cancer cell proliferation.

Sperm-associated antigen 9 (SPAG9) was recently reported to be overexpressed in several cancers and associated with the malignant behavior of cancer cells. However, the expression pattern of SPAG9 and its clinical significance in human prostate cancer have not been reported. In the present study, we analyzed SPAG9 expression in human prostate cancer tissues by immunohistochemistry and found that SPAG9 was overexpressed in 36.5 % of prostate cancer specimens. There was a significant association between SPAG9 overexpression and tumor stage (p = 0.0020) and Gleason score (p = 0.0377). Transfection of SPAG9 plasmid was performed in PC-3 cell line and siRNA knockdown was carried out in DU145 cells. Colony formation and MTT showed that SPAG9 overexpression promoted while siRNA knockdown inhibited prostate cancer cell proliferation. In addition, we found that SPAG9 could regulate cyclin D1 and cyclin E protein expression. In conclusion, SPAG9 is overexpressed in human prostate cancers and contributes to prostate cancer cell growth, possibly through cyclin protein regulation.