Xu Xudong, Chen Da, Ye Bo, Zhong Fangming, Chen Gang
Department of Thoracic Surgery, Hangzhou Red Cross Hospital, Hangzhou, Zhejiang 310000, P.R. China.
Int J Mol Med. 2015 Jun;35(6):1610-6. doi: 10.3892/ijmm.2015.2167. Epub 2015 Apr 2.
Curcumin is known for its anti-proliferative effects in lung cancer cells. Studies have demonstrated that an increase in the levels of intracellular free calcium ([Ca2+]i) is involved in curcumin-induced apoptosis. In this study, we aimed to investigate the involvement of calcium overload in the anti-proliferative effects of curcumin on lung cancer cells and the possible mechanisms involved. A549 and H1299 lung cancer cells were incubated with serial diluted curcumin. MTT assay was used to assess the cytotoxic effects of curcumin on the lung cancer cells; the inositol 1,4,5-trisphosphate receptor (IP3R, a key regulator of [Ca2+]i signaling) was blocked by its specific inhibitor, xestospongin C (XSC). Hoechst 33342, Fura-2/AM and rhodamine 123 fluorescence staining was employed to detect the apoptosis, the [Ca2+]i level and mitochondrial potential in the lung cancer cells. The expression levels of B-cell lymphoma-2 (Bcl-2), cleaved caspase-3 and cleaved caspase-9, and the phosphorylation level of IP3R were evaluated by western blot analysis. Our results revealed that curcumin inhibited cell growth, increased the [Ca2+]i level and increased the apoptosis of the lung cancer cells in a concentration-dependent manner. However, XSC attenuated the increase in the [Ca2+]i level and apoptosis, and also reversed the curcumin-induced loss of mitochondrial potential potential. Treatment with curcumin downregulated the expression of Bcl-2, and elevated the phosphorylation level of IP3R in a concentration-dependent manner. However, this effect was not reversed by treatment with XSC. In conclusion, the cytotoxic effects of curcumin on lung cancer cells were induced by calcium overload, which involves Bcl-2 mediated IP3R phosphorylation.
姜黄素以其对肺癌细胞的抗增殖作用而闻名。研究表明，细胞内游离钙（[Ca2+]i）水平的升高参与了姜黄素诱导的细胞凋亡。在本研究中，我们旨在探讨钙超载在姜黄素对肺癌细胞抗增殖作用中的作用及可能的机制。将A549和H1299肺癌细胞与系列稀释的姜黄素孵育。采用MTT法评估姜黄素对肺癌细胞的细胞毒性作用；用其特异性抑制剂西司他汀C（XSC）阻断肌醇1,4,5-三磷酸受体（IP3R，[Ca2+]i信号的关键调节因子）。采用Hoechst 33342、Fura-2/AM和罗丹明123荧光染色检测肺癌细胞的凋亡、[Ca2+]i水平和线粒体电位。通过蛋白质印迹分析评估B细胞淋巴瘤-2（Bcl-2）、裂解的半胱天冬酶-3和裂解的半胱天冬酶-9的表达水平以及IP3R的磷酸化水平。我们的结果显示，姜黄素以浓度依赖的方式抑制细胞生长、增加[Ca2+]i水平并增加肺癌细胞的凋亡。然而，XSC减弱了[Ca2+]i水平和凋亡的增加，并且还逆转了姜黄素诱导的线粒体电位丧失。姜黄素处理下调了Bcl-2的表达，并以浓度依赖的方式提高了IP3R的磷酸化水平。然而，XSC处理并未逆转这种作用。总之，姜黄素对肺癌细胞的细胞毒性作用是由钙超载诱导的，这涉及Bcl-2介导的IP3R磷酸化。
