The Experiment Study Of Expression Of RhoC And POCK-1 And Their Effects On MAPK And Akt Proteins In Prostate Carcinoma

Prostate cancer is one of common malignant tumors in men. Extensive bone metastasis is the main death cause in prostate cancer patients. Rho family is a kind of small molecule G protein discovered recently, RhoC is a member of the family involved in cell signal transduction and regulation of the actin cytoskeleton and other important biological processes. RhoC expression is related to tumor migration, invasion and metastasis and is considered to be the molecular switch of tumor metastasis. Rho kinase ROCK is one of the main effect molecules of Rho family. In this study we observed RhoC, ROCK-1 expression in prostate cancer and explored the mechansim of RhoC/ROCK-1 signal transduction pathway in metastasis of prostate cancer.Material and MethodsTissue specimens from 73 patients with prostate carcinoma and corresponding para-cancer tissues were obtained by prostate cancer biopsy (15 cases) or radical prostatectomy (58 cases). According to Jewett-Whitmore-Prout clinical staging system,28 cases were belong to A or B,45 cases were belong to C or D. Refer to Gleason histological grade standard,39 cases were well differentiated,34 cases were poorly differentiated.32 cases had bone metastasis. Expression of RhoC/ROCK-1 mRNA were detected by RT-PCR; Western blot and immunohistochemistry were performed on expression of RhoC/ROCK-1 protein; Eukaryotic expression plasmids of RhoC were constructed and transfected into non-metastatic prostate cancer cell line PC-3M-2B4; p-MAPK and p-Akt were detected by Western bolt.ResultsImmunohistochemical staining:RhoC and ROCK-1 positive rate in prostate cancer was 65.5% (38/58) and 69.0% (40/58), were significantly higher than the adjacent tissues 29.3% (17/58),34.5% (20/58). Correlation analysis showed that, RhoC and ROCK-1 expression was significantly correlated (rs=0.487, P<0.01).Western Blot Results:RhoC and ROCK-1 expression in 58 cases prostate cancer tissue was significantly higher than that of adjacent tissues. RhoC and ROCK-1 expression was significantly correlated with the expression of phosphorylated MAPK and Akt.RT-PCR Results:RhoC mRNA and ROCK-1 mRNA expression can be observed in 73 cases of prostate cancer tissue samples, but not in adjacent tissues. The average gray of RhoC mRNA and ROCK-1 mRNA in prostate cancer tissue were 0.61±0.18 and 0.65±0.21 respectively, significantly higher than that of adjacent tissues (0.29±0.09,0.33±0.12; both P<0.05). RhoC mRNA and ROCK-ⅠmRNA positive rates in prostate cancer tissues were 72.6%(53/73) and 68.5% (50/73), in the corresponding adjacent tissues were 34.2% (25/73) and 38.4%(28/73, P＜0.01).Correlation between RhoC/ROCK-1 expression and clinical pathologic parameters:RhoC and ROCK-1 protein expression increased as the malignancy and clinical stage increased. RhoC mRNA and ROCK-1 mRNA expression in the bone metastasis group was higher than that without metastasis (P<0.05). In well-differentiated prostate cancer, RhoC mRNA and ROCK-1 mRNA expression was higher than that of poorly differentiated group, the difference had no significance (P>0.05).Phosphorylated MAPK and Akt expression in PC-3M-2B4 cells transfected RhoC:Phosphorylated MAPK and Akt expression in empty vector transfected PC-3M-2B4 cells was 0.262±0.096 and 0.325±0.071, similar with that of control group 0.182±0.026 and 0.318±0.041. Expression level of phosphorylated MAPK and Akt was significantly elevated in RhoC transfected group (0.913±0.086,1.037±0.035)(P<0.01).Conclusions(1)Expression levels of RhoC and ROCK-1 in prostate carcinoma are higher than those in corresponding para-cancer tissues, and the expression of RhoC and ROCK-1 showed significant positive correlation with distant metastasis;(2) RhoC/ROCK-1 may be involved in the development, invasion and metastasis of prostate carcinoma.