Ishaq Mohammad, Khan Mohammad Aslam, Sharma Kapil, Sharma Gaurav, Dutta Rajesh Kumar, Majumdar Sekhar
Division of Cell Biology and Immunology, CSIR-Institute of Microbial Technology, Chandigarh 160 036, India.
Division of Cell Biology and Immunology, CSIR-Institute of Microbial Technology, Chandigarh 160 036, India.
Biochim Biophys Acta. 2014 Dec;1840(12):3374-84. doi: 10.1016/j.bbagen.2014.08.019. Epub 2014 Sep 12.
Gambogic acid is a potent anticancer agent and has been found effective against various types of cancer cells. The present study was addressed to explore the cytotoxic potential of Gambogic acid and the modulation of autophagy and apoptosis in bladder cancer cells T24 and UMUC3.
Bladder cancer cell lines T24 and UMUC3 were treated with Gambogic acid, apoptosis was checked by flow-cytometry and expression of various autophagy and apoptosis related proteins was monitored by Western blotting. Confocal microscope was used for colocalization of p62 and Beclin-1.
Gambogic acid induces reactive oxygen species, and elicits a strong autophagic response by activating JNK at earlier time points, which is inhibited at later time points with the activation of caspases. Reactive oxygen species mediated caspase activation causes degradation of autophagic proteins, cleavage of molecular chaperones (Hsp90 and GRP-78) and adaptor proteins (p62 and NBR1). Gambogic acid treatment results in mitochondrial hyperpolarization and cytochrome c release and activates caspases involved in both extrinsic and intrinsic apoptotic pathways. Gambogic acid abrogates NF-κB activation by ROS mediated inhibition of IκB-α phosphorylation. Functionally Gambogic acid induced autophagy acts as a strong cell survival response and delays caspase activation.
Our study provides the new insights about the mechanism of Gambogic acid induced modulation of autophagy and apoptosis in bladder cancer cells. All the molecular events responsible for Gambogic acid induced autophagy and apoptosis are mediated by reactive oxygen species.
Since Gambogic acid targets various cell survival molecules therefore, it may be considered as a potential anticancer agent against bladder cancer.
藤黄酸是一种有效的抗癌剂，已被发现对多种类型的癌细胞有效。本研究旨在探讨藤黄酸对膀胱癌细胞T24和UMUC3的细胞毒性潜力以及自噬和凋亡的调节作用。
用藤黄酸处理膀胱癌细胞系T24和UMUC3，通过流式细胞术检测凋亡情况，并通过蛋白质免疫印迹法监测各种自噬和凋亡相关蛋白的表达。使用共聚焦显微镜检测p62和Beclin-1的共定位。
藤黄酸诱导活性氧生成，并在早期通过激活JNK引发强烈的自噬反应，而在后期随着半胱天冬酶的激活而受到抑制。活性氧介导的半胱天冬酶激活导致自噬蛋白降解、分子伴侣（Hsp90和GRP-78）和衔接蛋白（p62和NBR1）的裂解。藤黄酸处理导致线粒体超极化和细胞色素c释放，并激活参与外源性和内源性凋亡途径的半胱天冬酶。藤黄酸通过活性氧介导的IκB-α磷酸化抑制作用消除NF-κB激活。在功能上，藤黄酸诱导的自噬起到强烈的细胞存活反应并延迟半胱天冬酶激活。
我们的研究为藤黄酸诱导膀胱癌细胞自噬和凋亡调节的机制提供了新的见解。藤黄酸诱导自噬和凋亡的所有分子事件均由活性氧介导。
由于藤黄酸靶向多种细胞存活分子，因此它可能被认为是一种潜在的抗膀胱癌药物。
