Pim-2 Cooperates with Downstream Factor XIAP to Inhibit Apoptosis and Intensify Malignant Grade in Prostate Cancer.

To find the exact downstream effector of Pim-2 pathway in prostate cancer cells, and to determine the means by which it affects prostate cancer. XIAP, Pim-2 and p-eIF4B expressions were detected in PCA and BPH tissues. Then the Pim-2 and XIAP expressions were manipulated using transfection or RNAi in prostatic cells. Finally, Pim-2/eIF4B/XIAP levels were examined in PCA tissues with different clinicopathologic features. XIAP was significantly higher in PCA than in BPH tissues. When Pim-2 was transfected into noncancerous prostate epithelial cells RWPE-1, Pim-2, p-eIF4B and XIAP were all significantly increased and the apoptosis rate was significantly decreased. When XIAP was transfected into RWPE-1 cells, XIAP was significantly increased with no impact on Pim-2, p-eIF4B and the apoptosis rate. When Pim-2 SiRNA was transfected into prostate cancer cells PC-3, Pim-2, p-eIF4B and XIAP were significantly decreased and the apoptosis rate was significantly increased. When XIAP SiRNA was transfected into PC-3 cells, XIAP was significantly decreased with no impact on Pim-2, p-eIF4B and apoptosis rate. Pim-2, p-eIF4B and XIAP were all significantly higher in PCA tissues with GS ≥8 than those with GS ≤7. XIAP is the downstream factor of Pim-2 pathway in prostate cancer cells. Pim-2 and XIAP cooperate in inhibiting the apoptosis of prostate cancer cells. The activation of Pim-2 pathway may predict higher GS in prostate cancer.