Heat Shock Proteins And P53 Play A Critical Role In BK Channel-mediated Tumor Cell Proliferation Inhibition And Apoptosis

The effects of K⁺ channels blockers on the proliferation in human cervix carcinoma cell LinesOBJECTIVE: Variant types of K⁺ channels are known to be involved in the proliferation of a number of malignant cell lines. To explore the role of different subtypes of K⁺ channels, especially the maxi-conductance Ca²⁺-activated K⁺ channels, in the proliferation of human cervix carcinoma HeLa cells, and to establish the foundation of the research about mechanism of proliferation regulating by K⁺ channels, the effects of several K⁺ channels blockers on the proliferation were observed in HeLa cells in vitro.METHODS: The effects of various dosages of tetraethylammonium, tetrandrine and glibenclamide on proliferation of human cervix carcinoma cells HeLa were observed by MTT assay. Detection of apoptosis and cell cycle analysis were performed with flow cytometry, and apoptosis was verified by agarose electrophoresis of cell DNA. To explore the mechanism of inhibitory effect on the proliferation in cancer cells by K⁺ channels blockers, the expressions of p53, p21 and Bax were analyzed by immunobloting.RESULTS: Tetraethylammonium and tetrandrine inhibited the proliferation of human cervix carcinoma cells HeLa in dosage and time dependent manner, and both of them induced apoptosis of the cancer cells. The cell cycle was arrested in G₀/G₁ phase in HeLa cells treated with tetraethylammonium or tetrandrine. Glibenclamide did not affect the growth of HeLa cells. The expressions of p53, p21 and Bax were up-regulated in human cervix carcinoma cells treated with Tetraethylammonium and tetrandrine.CONCLUSIONS: Voltage-gated K⁺ channels, especially maxi-conductive calcium-activated K⁺ channels might play an important role in regulating of proliferation of cervix carcinoma cells HeLa. The anti-tumor effect of tetrandrine may be due to up-regulating the expressions of p53, p21 and Bax. Maybe maxi-conductive calcium-activated K⁺ channels will become a potential therapeutic target in cervical cancer. Heat shock proteins and p53 play a critical role in K⁺ channel-mediated tumor cell proliferation and apoptosisOBJECTIVE: Variant types of K⁺ channels are known to be involved in the proliferation of a number of malignant cell lines. To explore the mechanisms involved in the proliferation of cancer cells by maxi-conductance Ca²⁺-activated K⁺ channels, and establish the foundation of the research about mechanism of proliferation regulating by K⁺ channels, the effects of several K⁺ channels blockers on the proliferation were observed in HeLa cells and A2780 cells in vitro.METHODS: The effects of various dosages of tetraethylammonium, tetrandrine and glibenclamide on proliferation of cancerious cell lines HeLa and A2780 were observed by MTT assay. Detection of apoptosis and cell cycle analysis were performed with flow cytometry, and apoptosis was verified by agarose electrophoresis of cell DNA and Hoechst 33258 staining. To explore the mechanism of inhibitory effects on the proliferation in cancer cells by K⁺ channels blockers, the expressions of p53, p21, Bax, HPV 18 E6, HSP70, HSP90α and HSP90β were analyzed by immunobloting. And the outward K⁺ currents of HeLa and A2780 were recorded by whole cell mode patch clamp technique to verify wether BK channels exist in the membrane of cancer cells.RESULTS: Tetraethylammonium and tetrandrine inhibited the proliferation of cancer cell line HeLa and A2780 in dosage dependent manner, and both of them induced apoptosis of the cancer cells. The cell cycle was arrested in G₀/G₁ phase in both cell lines treated with tetraethylammonium or tetrandrine. Glibenclamide did not affect the growth of HeLa and A2780 cells. The expressions of p53, p21 and Bax were up-regulated, and HSP70, but expressions of HSP90α and HSP90β were down-regulated in HeLa and A2780 cells treated with Tetraethylammonium and tetrandrine. The epression of HPV 18 E6 was not affected by K⁺ blockers. The tetraethylammonium- and tetrandrine-sensitive outward K⁺ currents were recorded in both cancer cells.CONCLUSIONS: Maxi-conductance calcium-activated K⁺ channels might play an important role in regulating of proliferation of cancer cells. The anti-tumor effect of tetrandrine may be due to up-regulating the expressions of p53, p21 and Bax and down-regulating the expressions of HSP70, HSP90α and HSP90β. Maybe maxi-conductive calcium-activated K⁺ channels will become a potential therapeutic target in cervical cancer.