This study aimed to examine the roles of reactive oxygen species (ROS) in cisplatin treatment of human prostate cancer cells; hormone-sensitive LNCaP and hormone-refractory PC3 and DU145 cells. Intracellular levels of ROS and H(2)O(2) were measured and visualized using specific fluorescent probes. NADPH oxidase (NOX) activity was detected by lucigenin chemiluminescence assay. Expression levels of NOX isoforms were determined by semi-quantitative RT-PCR. Cisplatin treatment increased the intracellular levels of ROS and H(2)O(2) in three prostate cancer cell lines. The increase was transient and robust in hormone-sensitive LNCaP cells compared with hormone-refractory PC3 and DU145 cells. Consistent with these findings, the NOX activity induced by cisplatin was higher in LNCaP cells than in PC3 and DU145 cells. Expression pattern of NOX isoforms varied among three cell lines and the NOX activity was independent of NOX expression. Taken together, we have shown that cisplatin induces production of ROS and H(2)O(2) via NOX activation in human prostate cancer cell lines, which is most prominent in hormone-sensitive LNCaP cells.
Abbreviations & AcronymsArp2/3 = actin-related protein 2/3 DAPI = 4′,6-diamidino-2-phenylindole ECM = extracellular matrix GAPDH = glyceraldehyde 3-phosphate dehydrogenase MMP = matrix metallopeptidase N-WASP = neuronal Wiskott-Aldrich syndrome protein siRNA = small interfering RNA SIRT1 = silent mating type information regulation 2 homolog 1 TSA = trichostatin A Objectives: Cortactin is overexpressed in various types of cancer and enhances cell motility. It has been recently reported that silent mating type information regulation 2 homolog 1 interacts with cortactin and promotes cell migration. Here, we examined the role of cortactin and silent mating type information regulation 2 homolog 1 in migration and invasion of prostate cancer cells.
Methods:The cortactin expression levels in DU145, LNCaP and PC3 prostate cancer cells, and in PrEC normal human prostate epithelial cells were evaluated by western blot analysis. In DU145 cells, the expression of cortactin or silent mating type information regulation 2 homolog 1 was inhibited by small interfering RNA, and the effects of their knockdown on migration and invasion were examined by cell migration and invasion assays. To determine the localization of cortactin and silent mating type information regulation 2 homolog 1, western blot and immunofluorescence microscopic analyses were carried out. The functional interaction between silent mating type information regulation 2 homolog 1 and cortactin was also studied by in vivo acetylation assay. Results: The protein expression of cortactin was significantly higher in DU145 cells than in other cell lines. Knockdown of cortactin or silent mating type information regulation 2 homolog 1 expression inhibited both migration and invasion of DU145 cells. Similarly to cortactin, silent mating type information regulation 2 homolog 1 was found to be predominantly expressed in the cytoplasm. Finally, the knockdown of silent mating type information regulation 2 homolog 1 expression increased the acetylation level of cortactin. Conclusions: Our findings suggest that inhibition of cortactin or silent mating type information regulation 2 homolog 1 expression attenuates migration and invasion of DU145 cells and this could represent a promising strategy to regulate metastasis of prostate cancer.
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