ABSTRACT
Background and purpose:Numerous researches indicated that the expression of pituitary tumor transforming gene1 (PTTG1) was correlated with the severity of glioma tumors. However the specific mechanism of PTTG1 is not clear in glioma. In this study, we explored the role and significance of PTTG1 in the invasion of glioma cells. Methods:Western blot was used to detect the expression of PTTG1 protein in various glioma cell lines. siRNA plasmid was used to transfect U87 cells. Western blot was used to analyze the expression of PTTG1 protein in transfected U87 cells. Matrigel invasion assay was used to detect the invasive ability in the cells being transfected in vitro. Western blot was used to analyze epithelial growth factor (EGF) induced protein phosphorylation of ARK5 and Akt in the cells being transfected PTTG1 plasmid (siPTTG1/U87) and scrambled siRNA (Scr/U87). Results:The expression of PTTG1 protein was higher in all glioma cell lines. After transfection, the invasion of siPTTG1/U87 was obviously decreased after 5 min with EGF stimulation than the Scr/U87, the phosphorylation of ARK5 and Akt was significantly enhanced. However, whether or not the existence of EGF, the phosphorylation of ARK5 and Akt had no differences in siPTTG1/U87. Conclusion:In glioma cells, PTTG1 protein is high expressed and maybe have an important function in glioma cells invasion through Akt-ARK5 signaling pathway.
ABSTRACT
Pituitary tumor-transforming gene-1 (PTTG1) is a proto-oncogene that promotes tumorigenesis and metastasis in numerous cell types and is overexpressed in a variety of human tumors. We have demonstrated that PTTG1 expression was up-regulated in both human prostate cancer specimens and prostate cancer cell lines. For a more direct assessment of the function of PTTG1 in prostate tumorigenesis, RNAi-mediated knockdown was used to selectively decrease PTTG1 expression in PC3 human prostate tumor cells. After three weeks of selection, colonies stably transfected with PTTG1-targeted RNAi (the knockdown PC3 cell line) or empty vector (the control PC3 cell line) were selected and expanded to investigate the role of PTTG1 expression in PC3 cell growth and invasion. Cell proliferation rate was significantly slower (28%) in the PTTG1 knockdown line after 6 days of growth as indicated by an MTT cell viability assay (P < 0.05). Similarly, a soft agar colony formation assay revealed significantly fewer (66.7%) PTTG1 knockdown PC3 cell colonies than control colonies after three weeks of growth. In addition, PTTG1 knockdown resulted in cell cycle arrest at G1 as indicated by fluorescence-activated cell sorting. The PTTG1 knockdown PC3 cell line also exhibited significantly reduced migration through Matrigel in a transwell assay of invasive potential, and down-regulation of PTTG1 could lead to increased sensitivity of these prostate cancer cells to a commonly used anticancer drug, taxol. Thus, PTTG1 expression is crucial for PC3 cell proliferation and invasion, and could be a promising new target for prostate cancer therapy.