Cdc25 phosphatases are important regulators of the cell cycle. Their abnormal expression detected in a number of tumors implies that their dysregulation is involved in malignant transformation. However, the role of Cdc25B in renal cell carcinomas remains unknown. To shed light on influence on renal cell carcinogenesis and subsequent progression, Cdc25B expression was examined by real-time RT-PCR and western blotting in renal cell carcinoma and normal tissues. 65 kDa Cdc25B expression was higher in carcinomas than in the adjacent normal tissues (P<0.05), positive correlations being noted with clinical stage and histopathologic grade (P<0.05). To additionally investigate the role of Cdc25B alteration in the development of renal cell carcinoma, Cdc25B siRNA was used to knockdown the expression of Cdc25B. Down-regulation resulted in slower growth, more G2/M cells, weaker capacity for migration and invasion, and induction of apoptosis in 769-P transfectants. Reduction of 14-3-3 protein expression appeared related to Cdc25B knockdown. These findings suggest an important role of Cdc25B in renal cell carcinoma development and provide a rationale for investigation of Cdc2B-based gene therapy.

No abstract

Acting via its receptor UNC5B, netrin-1, one of the major neuronal guidance cues, plays an important role in angiogenesis, neurogenesis, tissue morphogenesis, embryonic development, cancer, inflammation, and various pathologies. However, its role has not been reported in prostate carcinoma. To investigate the association of netrin-1 and UNC5B expression with prostate carcinoma, several human prostate carcinoma cell lines were cultured and the expression levels of netrin-1 and UNC5B were determined by real-time PCR and Western blot. Calphostin C, (the inhibitor of PKC α) and phorbol-12-myristate 13-acetate-PMA (the agonist of PKC α) were used to treat the prostate carcinoma cells, and the cell proliferation and invasion abilities were measured by CCK-8 and wound-healing assays. Proliferation of DU145 cells was affected by the recruitment of PMA and calphostin C in a dose-dependent manner. By immunofluorescence, we identified the localization of netrin-1 and UNC5B in prostate carcinoma cell lines (DU145, 22RV1, PC3, PC3M, and RWEP) and found that netrin-1 was highly expressed in the nucleolus but there was no expression of UNC5B. The co-localization expression of PKC α and UNC5B was confirmed by the confocal immunofluorescence. Higher netrin-1 and lower UNC5B expression in all prostate carcinoma cell lines indicated that netrin-1 and UNC5B could be used to predict metastasis.

With a special interest towards a better understanding of signal pathways, we attempted to discover a safer and more effective therapeutic strategy for kidney carcinoma. Recent studies had suggested a role mediated by PKCα for netrin-1 and its receptors in the initiation and progression of tumors. Real-time PCR and western blotting were used to determine the expression levels of netrin-1 and UNC5B. We made use of the agonist of PKCα (phorbol-12-myristate 13-acetate-PMA) and the inhibitor of PKCα (calphostin C) to treat renal cell carcinoma (RCC) cells, and MTT assays were used to measure cell proliferation. By immunofluorescence, we identified the localization of netrin-1 and UNC5B in RCC cell lines 769-P and ACHN. The expression of UNC5B in tumor tissues was significantly downregulated compared to the corresponding normal tissues in which netrin-1 was upregulated. In low grade tumors, UNC5B expression was more prominent while netrin-1 expression was the opposite when compared with high grade ones. Proliferation of ACHN cells was concentration dependent in the presence of PMA and calphostin C. Netrin-1 and UNC5B expressions were upregulated in cells treated with PMA while calphostin C reversed this upregulation. By immunofluorescence, we identified that netrin-1 was highly expressed in the nuclear but none of UNC5B. Our data highly suggested that PMA-induced upregulation and calphostin C-induced reversion of netrin-1 and UNC5B in kidney carcinoma were accompanied by the activation of the netrin-1/UNC5B pathways.