Selective activation of members of the signal transducers and activators of transcription family in prostate carcinoma

Purpose: Cytokines, hormones and growth factors use signal transducers and activators of transcription (STAT) signaling pathways to control various biological responses, including development, differentiation, cell proliferation and survival. Constitutive activation of STATs has been found in a wide variety of human tumors. In this study we examined the activity of STATs in primary human prostate tissues. Materials and Methods: STAT activity was determined in 104 human primary prostate tissues, including 42 tumors, 42 matched normal prostates adjacent to tumors and 20 normal prostates from donors without cancer by electromobility shift assay. Results: Significant levels of activated Stat4 and Stat6 were detected in primary prostate tissues. However, little or no expression of active Stat1, Stat2 or Stat5 was detected in primary prostate tissues. Significantly higher levels of constitutive Stat6 activity were found in prostate carcinomas compared with levels in normal tissue adjacent to tumors and normal prostates from donors without prostate cancer. There was no significant difference in Stat6 activity in normal prostate tissues adjacent to tumors and normal prostates from donors without prostate cancer. The levels of Stat4 activity varied but failed to yield statistically significant differences among tumors, matched normal prostates adjacent to tumors and normal prostates from donors without cancer. Conclusions: We have previously shown that Stat3 is activated in prostate cancer. The results of the current study demonstrate that in addition to Stat3, Stat6 is selectively activated in prostate cancer.