The Significance Of Elevated Expression Of PAK2 In Castration-resistent Prostate Cancer

Objective: Detect the different expression of PAK2 and PAK2-S141 P in human different prostatic tissues,cell proliferation assay,cell invasion assay and animal experiment were used to explore the mechanism of PAK2 in the course of ADPC transformed to CRPC.Methods:1、We use immunohistochemistry(IHC) method to detect the protein expression of PAK2 and PAK2-S141 P in benign prostatic hyperplasia(BPH), androgen dependent prostate cancer(ADPC) and castrate-resistant prostate cancer(CRPC). ADPC group was divided to high-grade subgroup and low-grade subgroup according to the Gleason score.2 、 LNCaP cells were cultured in steroid depleted medium for 48 h and subsequently treated with DHT in the different time of 30 min,2h,4h,8h,24 h,48h,and 72h; MDV3100 treat LNCaP cells for 24 h,then western blot see the PAK2 expression,exploring the effect of AR passway to PAK2. Transfect C4-2 cells with specific small interfering RNAs(siRNAs) targeting PAK2, we use western blot to conform the effects of PAK2 knockout, then observe the clonogenic activity and invasion activity.3、In the animal experiment,we established subcutaneous xenograft tumor models from implanted PC3 cells, the mice were randomly divided into experimental group and control group,PAK2 inhibitor PF-3758309 was used in the experimental group, control group was treated with DMSO,then recorded the tumor growth curves and compared the tumor volume of the two groups,finally,we detected the expression of Ki67,Caspase-3 and PAK2-S141 P in the different groups through IHC.Results:1.The expression of PAK2 and PAK2-S141 P protein in the human prostate cancer tissues was higher than BPH tissues,statistical analysis showed significant difference. additionally, the expression of PAK2 and PAK2-S141 P in the CRPC tissues was higher than ADPC tissues, significant difference was also found through statistical analysis.2. DHT can upreulate the expression of PAK2 In LNCaP cells and AR inhibitor MDV3100 can up regulate the expression of PAK2. The effect of PAK2 knockout on the migration and proliferation in the prostate cancer C4-2 cell lines: The downregulation of PAK2 protein in C4-2 cells caused a reduction in the clonogenic activity in Matrigel and in the invasion activity. The proliferative activity and of the prostate cancer C4-2 cells which PAK2 was knockout was significantly decreased compared with control groups, there was significant difference(P <0.05).3.In the animal experiment, the xenograft of PC3 cells group treated with PAK2 inhibitor PF-3758309 had less tumor size compared to the control group,IHC showed control group had more Caspase-3 expression and less Ki67, PAK2-S141 P expression, significant difference was also showed after statistical analysis(P <0.05).Conclusions: The expression of PAK2 and its active form PAK2-S141 P in human ADPC tissues was higher than BPH tissues. The expression of PAK2 and PAK2-S141 P protein in the CRPC tissues was higher than ADPC tissues. PAK2 may play an important role in the progression of prostate cancer. The growth of prostate cancer C4-2 cell lines and xenografts in nude mice can be inhibited by PAK2 knockout, so PAK2 may be one of the therapeutic targets of prostate cancer, especially in CRPC.