Department of Clinical Laboratory, The First Affiliated Hospital of Zhengzhou University, Zhengzhou, 450000, Henan, China.
Department of Neurosurgery, The First Affiliated Hospital of Zhengzhou University, Zhengzhou, 450000, Henan, China.
J Exp Clin Cancer Res. 2019 Feb 13;38(1):77. doi: 10.1186/s13046-019-1090-6.
Metformin, a first-line drug for type 2 diabetes, could induce apoptosis in cancer cells. However, the concentration of glucose affects the effect of metformin, especially low glucose in the culture medium can enhance the cytotoxicity of metformin on cancer cells. Since mitochondria and endoplasmic reticulum is vital for maintaining cell homeostasis, we speculate that low glucose and metformin-induced cell apoptosis may be associated with mitochondria and endoplasmic reticulum. ASK1, as apoptosis signaling regulating kinase 1, is associated with cell apoptosis and mitochondrial damage. This study was designed to investigate the functional significance of ASK1, mitochondria and endoplasmic reticulum and underlying mechanism in low glucose and metformin-induced cell apoptosis.
An MTT assay was used to evaluate cell viability in SKOV3, OVCAR3 and HO8910 human ovarian cancer cells. Cell apoptosis was analyzed by flow cytometry. The expression of ASK1 was inhibited using a specific pharmacological inhibitor or ASK1-siRNA. Immunofluorescence was used to detect mitochondrial damage and ER stress. Nude mouse xenograft models were given metformin or/and NQDI-1, and ASK1 expression was detected using immunoblotting. In addition, subcellular fractionation of mitochondria was performed to assay the internal connection between ASK1 and mitochondria.
The present study found that low glucose in culture medium enhanced the anticancer effect of metformin in human ovarian cancer cells. Utilization of a specific pharmacological inhibitor or ASK1-siRNA identified a potential role for ASK1 as an apoptotic protein in the regulation of low glucose and metformin-induced cell apoptosis via ASK1-mediated mitochondrial damage through the ASK1/Noxa pathway and via ER stress through the ROS/ASK1/JNK pathway. Moreover, ASK1 inhibition weakened the antitumor activity of metformin in vivo. Thus, mitochondrial damage and ER stress play a crucial role in low glucose-enhanced metformin cytotoxicity in human ovarian cancer cells.
These data suggested that low glucose and metformin induce cell apoptosis via ASK1-mediated mitochondrial damage and ER stress. These findings indicated that the effect of metformin in anticancer treatment may be related to cell culture conditions.
二甲双胍是治疗 2 型糖尿病的一线药物，它可以诱导癌细胞凋亡。然而，葡萄糖浓度会影响二甲双胍的效果，特别是培养基中的低糖可以增强二甲双胍对癌细胞的细胞毒性。由于线粒体和内质网对于维持细胞内环境稳定至关重要，我们推测低糖和二甲双胍诱导的细胞凋亡可能与线粒体和内质网有关。ASK1（凋亡信号调节激酶 1）作为一种凋亡信号调节激酶，与细胞凋亡和线粒体损伤有关。本研究旨在探讨 ASK1、线粒体和内质网在低糖和二甲双胍诱导的细胞凋亡中的功能意义及其潜在机制。
用 MTT 法检测 SKOV3、OVCAR3 和 HO8910 人卵巢癌细胞的细胞活力。用流式细胞术分析细胞凋亡。用特定的药理学抑制剂或 ASK1-siRNA 抑制 ASK1 的表达。用免疫荧光法检测线粒体损伤和内质网应激。用免疫印迹法检测裸鼠异种移植模型中 metformin 或/和 NQDI-1 给药后的 ASK1 表达。此外，进行亚细胞线粒体分离以检测 ASK1 与线粒体之间的内在联系。
本研究发现，培养基中的低糖增强了二甲双胍在人卵巢癌细胞中的抗癌作用。利用特定的药理学抑制剂或 ASK1-siRNA，发现 ASK1 作为一种凋亡蛋白，通过 ASK1 介导的线粒体损伤通过 ASK1/Noxa 途径，以及通过 ROS/ASK1/JNK 途径通过内质网应激，在调节低糖和二甲双胍诱导的细胞凋亡中发挥潜在作用。此外，ASK1 抑制减弱了 metformin 在体内的抗肿瘤活性。因此，线粒体损伤和内质网应激在低糖增强人卵巢癌细胞中二甲双胍细胞毒性中起关键作用。
这些数据表明，低糖和二甲双胍通过 ASK1 介导的线粒体损伤和内质网应激诱导细胞凋亡。这些发现表明，二甲双胍在抗癌治疗中的作用可能与细胞培养条件有关。
