Saguyod Sofia Jade U, Alhallak Iad, Simmen Rosalia C M, Velarde Michael C
Institute of Biology, College of Science, University of the Philippines Diliman, Quezon City, PH 1101, Philippines.
Department of Physiology and Biophysics, University of Arkansas for Medical Sciences, Little Rock, AR 72205, USA.
Oncol Lett. 2020 Nov;20(5):249. doi: 10.3892/ol.2020.12112. Epub 2020 Sep 17.
Metformin (MET) constitutes the first-line treatment against type 2 diabetes. Growing evidence linking insulin resistance and cancer risk has expanded the therapeutic potential of MET to several cancer types. However, the oncostatic mechanisms of MET are not well understood. MET has been shown to promote the expression of progesterone receptor (PGR) and other antitumor biomarkers in patients with non-diabetic endometrial cancer (EC) and in Ishikawa EC cells cultured in normal glucose (5.5 mM) media. Therefore, the present study aimed to assess the effects of MET on EC cells under conditions simulating diabetes. Ishikawa cells treated with 10 nM 17β-estradiol (E2) and/or 100 µM MET and exposed to normal and high (17.5 mM) concentrations of glucose were evaluated for proliferative and expression status. Under normal glucose conditions, MET attenuated E2-induced cell proliferation and cyclin D1 gene expression, and increased total and transcript levels. MET inhibited Ishikawa cell spheroid formation only in the absence of E2 treatment. In E2-treated cells under high glucose conditions, MET showed no effects on cell proliferation and spheroid formation, and increased total but not transcript levels. Transfection with Krüppel-like factor 9 small interfering RNA increased transcript levels, irrespective of glucose environment. Medroxyprogesterone acetate downregulated expression more effectively with metformin under high compared with normal glucose conditions. To evaluate the potential mechanisms underlying the targeting of PGR by MET, E2-treated cells were incubated with MET and the AMPK inhibitor Compound C, or with the AMPK activator 5-aminoimidazole-4-carboxamide ribonucleotide (AICAR), under normal glucose conditions. Compound C abrogated the effects of MET on while AICAR increased transcript levels, albeit less effectively compared with MET. The present results demonstrate the glucose-dependent effects of MET on isoform expression, which may inform the response to progestin therapy in diabetic women with EC.
二甲双胍（MET）是2型糖尿病的一线治疗药物。越来越多的证据表明胰岛素抵抗与癌症风险相关，这使得MET在多种癌症类型中的治疗潜力得到了扩展。然而，MET的抑癌机制尚未完全明确。在非糖尿病子宫内膜癌（EC）患者以及在正常葡萄糖（5.5 mM）培养基中培养的 Ishikawa EC 细胞中，MET已被证明可促进孕激素受体（PGR）和其他抗肿瘤生物标志物的表达。因此，本研究旨在评估MET在模拟糖尿病条件下对EC细胞的影响。对用10 nM 17β-雌二醇（E2）和/或100 µM MET处理并暴露于正常和高（17.5 mM）葡萄糖浓度的 Ishikawa 细胞进行增殖和表达状态评估。在正常葡萄糖条件下，MET可减弱E2诱导的细胞增殖和细胞周期蛋白D1基因表达，并增加总量和转录水平。MET仅在未进行E2处理的情况下抑制 Ishikawa 细胞球体形成。在高葡萄糖条件下经E2处理的细胞中，MET对细胞增殖和球体形成无影响，且增加了总量但未增加转录水平。用Krüppel样因子9小干扰RNA转染可增加转录水平，而与葡萄糖环境无关。与正常葡萄糖条件相比，在高葡萄糖条件下醋酸甲羟孕酮与二甲双胍联合使用时能更有效地下调表达。为了评估MET靶向PGR的潜在机制，在正常葡萄糖条件下，将经E2处理的细胞与MET和AMPK抑制剂化合物C或与AMPK激活剂5-氨基咪唑-4-甲酰胺核糖核苷酸（AICAR）一起孵育。化合物C消除了MET对的影响，而AICAR增加了转录水平，尽管与MET相比效果较差。本研究结果证明了MET对异构体表达的葡萄糖依赖性影响，这可能为患有EC的糖尿病女性对孕激素治疗的反应提供参考。
