Chloride channel involved in the regulation of curcumin-induced apoptosis of human breast cancer cells

Objective:To investigate the role of ClC-3 chloride channel in the proliferation of breast cancer cell line Mcf-7 treated with curcumin and its specific mechanism.Methods:MTT assay was used to detect the effect of chloride channel blocker (DIDS) and curcumin on Mcf-7 and human normal cell viability. Patch-clamp technique was used to determine the current density before and after drug treatment. Apoptosis assay by flow cytometry was performed for further examination of cell apoptosis.Results:Curcumin had toxicity on Mcf-7 and HUVEC cells and DIDS reduced the survival rate of Mcf-7 cells by inhibiting proliferation. Curcumin could activate the chloride ion current on MCF-7 cell membrane, which would be inhibited by DIDS. Finally, curcumin in low concentration combined with DIDS could significantly promote the MCF-7 cells apoptosis.Conclusions:Our results suggest that ClC-3 protein is involved in the regulation of curcumin induced proliferation inhibiting in breast cancer cells through inducing cell apoptosis. ClC-3 may be a potential target of tumor therapy.

Chloride channel involved in the regulation of curcumin-induced apoptosis of human breast cancer cells

Objective: To investigate the role of ClC-3 chloride channel in the proliferation of breast cancer cell line Mcf-7 treated with curcumin and its specific mechanism. Methods: MTT assay was used to detect the effect of chloride channel blocker (DIDS) and curcumin on Mcf-7 and human normal cell viability. Patch-clamp technique was used to determine the current density before and after drug treatment. Apoptosis assay by flow cytometry was performed for further examination of cell apoptosis. Results: Curcumin had toxicity on Mcf-7 and HUVEC cells and DIDS reduced the survival rate of Mcf-7 cells by inhibiting proliferation. Curcumin could activate the chloride ion current on MCF-7 cell membrane, which would be inhibited by DIDS. Finally, curcumin in low concentration combined with DIDS could significantly promote the MCF-7 cells apoptosis. Conclusions: Our results suggest that ClC-3 protein is involved in the regulation of curcumin induced proliferation inhibiting in breast cancer cells through inducing cell apoptosis. ClC-3 may be a potential target of tumor therapy.

Effects of Cl- channel blockers on the cardiac ATP-sensitive K+ channel

To explore whether Cl- channel blockers interact with the ATP-sensitive K+ (KATP) channel, I have examined the effect of two common Cl- channel blockers on the KATP channel activity in isolated rat ventricular myocytes using patch clamp techniques. In inside-out patches, 4,4'-diisothio-cyanatostilbene-2,2'-disulfonic acid (DIDS) and niflumic acid applied to bath solution inhibited the KATP channel activity in a concentration-dependent manner with IC50 of 0.24 and 927 muM, respectively. The inhibitory action of DIDS was irreversible whereas that of niflumic acid was reversible. Furthermore, DIDS-induced block was not recovered despite exposure to ATP (1 mM). In cell-attached and inside-out patches, DIDS blocked the pinacidil- or 2,4-dinitrophenol (DNP)-induced KATP channel openings. In contrast, niflumic acid did not block the pinacidil-induced KATP channel openings in inside-out patches, but inhibited it in cell-attached patches. DIDS and niflumic acid produced additional block in the presence of ATP and did not affect current-voltage relationship and channel kinetics. All these results indicate that DIDS among Cl- channel blockers specifically blocks the cardiac KATP channel.

The Effect of Choloride Channel on Aqueous Humor Production

Regulating the cell volume is an important factorin secretory function of epithelial cells and regulatory volume decrease (RVD) phenomenon is involved in response to the changes of cell volume and osmolarity. RVD of epithelial cells reflects cellular release of K+ and C1- through channels and K+ and C1- channels were verified in the basal membrane of the non pigmented ciliary epithelial cells. Therefore, we attempted to observe the involvement of C1- channel in aqueous humor production by performing the fluorophotometry after administration of the DIDS(4.4-diisothiocyanatostilbene-2-2-disulfonic acid), the C1 channel blocker. Ten white New Zealand rabbits, 5 for tonometry and 5 for fluorophotometry, were used. One eye was injected 2x10-4M DIDS intravitreally using microsyringe and the other eye was injected normalsaline as a control in each rabbits. Tonometry was performed before the injection and every hour after dosing for 5 hours. Fluorophotometry was performed every 30 minutes for 3 hours starting 2 hours after injection. Wilcoxon`s signed rank test was used for statistical analysis. DIDS decreased intraocular pressure by 12.5%(P<0.05) and reduced aqueous humor flow rate by 28.5%(P0.05). In conclusion, it was observed.