1.
Effects of Intermediate-Conductance Ca(2+)-Activated K(+) Channels on Human Endometrial Carcinoma Cells.
Zhang, Y, Feng, Y, Chen, L, Zhu, J
Cell biochemistry and biophysics. 2015;(2):515-25
Abstract
The objective of this study was to investigate the effect of intermediate-conductance Ca(2+)-activated K(+) (KCa3.1) channels on the cell proliferation, cell cycle, apoptosis, migration, and invasion in endometrial cancer (EC) cells. Human EC cell lines HEC-1-A and Ishikawa were cultured in vitro and transfected with recombinant plasmid containing KCa3.1-targeting shRNA. RT-qPCR and Western blot were used to examine the mRNA and protein expression levels of KCa3.1 channels in transfected cells. In addition, the specific inhibitor of KCa3.1, TRAM-34, was used to examine the effect of KCa3.1 blockage on migration capacity and invasiveness of EC cells using transwell assay. Proliferation and apoptotic rates of EC cells transfected with KCa3.1 shRNA or treated with TRAM-34 were analyzed using MTT, BrdU incorporation assay, and flow cytometry. Expression of cell cycle proteins and metalloproteinase-2 (MMP-2) was evaluated by RT-qPCR and Western blotting. TRAM-34 treatment and KCa3.1 silencing using shRNA dramatically suppressed both the mRNA and protein expression of KCa3.1 channels (P < 0.01) compared with control groups. Blockage of KCa3.1 by TRAM-34 treatment and KCa3.1 shRNA transfection exerted inhibitory effect on cell growth of both EC cell lines, as demonstrated by increased cell population at G0-G1 phase and decreased cell population at S phase. However, both the treatments did not result in significant changes in the apoptotic rate (P > 0.05) compared to controls. Protein expressions of cyclin D1, cyclin E, and survivin were significantly decreased in the experimental groups comparing to control. We showed that TRAM-34 treatment led to significantly inhibited migration, invasion, and MMP-2 expression in HEC-1-A and Ishikawa cells, compared with the control group (P < 0.01). Blockage of KCa3.1 channel activity or expression inhibits cell proliferation and cell cycle progression without inducing apoptosis in EC cells. Moreover, TRAM-34 could reduce the ability of EC cells to migrate and invade, which might be related to reduced expression of MMP-2.
2.
A novel calmodulin antagonist O-(4-ethoxyl-butyl)-berbamine overcomes multidrug resistance in drug-resistant MCF-7/ADR breast carcinoma cells.
Liu, R, Zhang, Y, Chen, Y, Qi, J, Ren, S, Xushi, MY, Yang, C, Zhu, H, Xiong, D
Journal of pharmaceutical sciences. 2010;(7):3266-75
Abstract
Multidrug resistance (MDR) mediated by the overexpression of the drug efflux protein P-glycoprotein is one of the major obstacles to successful cancer chemotherapy. The development of safe and effective MDR-reversing agents is an important approach to addressing this problem clinically. In this study, we evaluated the P-gp-modulatory potential of O-(4-ethoxyl-butyl)-berbamine (EBB), a novel calmodulin antagonist and derivative of bisbenzylisoquinoline alkaloid, which significantly improved the chemosensitivity of P-glycoprotein-mediated multidrug-resistant cells to doxorubicin compared with the efficacy of a conventional P-glycoprotein inhibitor, verapamil. EBB not only blocked the function of P-glycoprotein confirmed by the fact that EBB increased intracellular accumulation of rhodamine 123 and doxorubicin but also inhibited the expression of P-glycoprotein actualized by downregulating P-glycoprotein. Furthermore, our results showed that cotreatment with EBB and doxorubicin resulted in marked G(2)/M arrest and apoptosis of MCF-7/ADR cells, accompanied by down-regulation of the proteins cdc2/p34 and cyclin B1 and increased the levels of calcium ions. Taken together, these results suggest that cotreatment with EBB and doxorubicin could strongly potentiate the antitumor activity of doxorubicin, thus may have significant clinical application in cancer chemotherapy.