Institute of Microbiology and Immunology, University of Belgrade, 11000 Belgrade, Serbia.
Eur J Pharmacol. 2011 Jan 25;651(1-3):41-50. doi: 10.1016/j.ejphar.2010.11.005. Epub 2010 Nov 27.
Metformin is an antidiabetic drug with anticancer properties, which mainly acts through induction of AMP-activated protein kinase (AMPK). In the present study we investigated the influence of metformin on the in vitro anticancer activity of the well-known chemotherapeutic agent cisplatin. Cell viability was determined by MTT and LDH release assay, oxidative stress and apoptosis (caspase activation, DNA fragmentation, and phosphatidylserine exposure) were assessed by flow cytometry, while activation of AMPK and Akt was analyzed by immunoblotting. Although metformin reduced the number of tumour cells when applied alone, it surprisingly antagonized the cytotoxicity of cisplatin towards U251 human glioma, C6 rat glioma, SHSY5Y human neuroblastoma, L929 mouse fibrosarcoma and HL-60 human leukemia cell lines. Only in B16 mouse melanoma cells metformin augmented the cytotoxicity of cisplatin. In U251 glioma cells metformin suppressed cisplatin-induced apoptotic cell death through inhibition of oxidative stress and caspase activation. The observed cytoprotection was apparently AMPK-independent, as metformin did not further increase cisplatin-induced AMPK activation in U251 cells and other pharmacological AMPK activators failed to block cisplatin-mediated apoptosis. On the other hand, metformin induced Akt activation in cisplatin-treated cells and Akt inhibitor 10-DEBC hydrochloride or phosphoinositide 3-kinase/Akt inhibitor LY294002 abolished metformin-mediated antioxidant and antiapoptotic effects. In conclusion, the antidiabetic drug metformin reduces cisplatin in vitro anticancer activity through AMPK-independent upregulation of Akt survival pathway. These data warrant caution when considering metformin for treatment of diabetic cancer patients receiving cisplatin or as a potential adjuvant in cisplatin-based chemotherapeutic regimens.
二甲双胍是一种具有抗癌特性的抗糖尿病药物，主要通过诱导 AMP 激活的蛋白激酶（AMPK）起作用。在本研究中，我们研究了二甲双胍对众所周知的化疗药物顺铂的体外抗癌活性的影响。通过 MTT 和 LDH 释放测定法测定细胞活力，通过流式细胞术评估氧化应激和细胞凋亡（半胱天冬酶激活、DNA 片段化和磷脂酰丝氨酸暴露），通过免疫印迹分析 AMPK 和 Akt 的激活。尽管二甲双胍单独应用时会减少肿瘤细胞的数量，但它出人意料地拮抗了顺铂对 U251 人神经胶质瘤、C6 大鼠神经胶质瘤、SHSY5Y 人神经母细胞瘤、L929 小鼠纤维肉瘤和 HL-60 人白血病细胞系的细胞毒性。只有在 B16 小鼠黑色素瘤细胞中，二甲双胍才增强了顺铂的细胞毒性。在 U251 神经胶质瘤细胞中，二甲双胍通过抑制氧化应激和半胱天冬酶激活来抑制顺铂诱导的细胞凋亡。观察到的细胞保护显然与 AMPK 无关，因为二甲双胍不会进一步增加 U251 细胞中顺铂诱导的 AMPK 激活，并且其他药理学 AMPK 激活剂不能阻断顺铂介导的细胞凋亡。另一方面，二甲双胍在顺铂处理的细胞中诱导 Akt 激活，Akt 抑制剂 10-DEBC 盐酸盐或磷脂酰肌醇 3-激酶/Akt 抑制剂 LY294002 消除了二甲双胍介导的抗氧化和抗凋亡作用。总之，抗糖尿病药物二甲双胍通过 AMPK 独立的 Akt 存活途径上调减少了顺铂的体外抗癌活性。当考虑将二甲双胍用于接受顺铂治疗的糖尿病癌症患者或作为基于顺铂的化疗方案的潜在辅助药物时，这些数据需要谨慎。
