Department of Anatomy, Inje University College of Medicine, Busan 614-735, Republic of Korea.
T2B Infrastructure Center for Ocular Disease, Inje University Busan Paik Hospital, Busan, Republic of Korea.
J Diabetes Res. 2019 Jan 9;2019:2376512. doi: 10.1155/2019/2376512. eCollection 2019.
Metformin and pioglitazone are two commonly prescribed oral hypoglycemic agents for diabetes. Recent evidence suggests that these drugs may contribute to bladder cancer. This study investigated molecular mechanism underlying effects of metformin and pioglitazone in bladder epithelial carcinogenesis in type 2 diabetes. The cells derived from human bladder epithelial cells (HBlEpCs) were treated with metformin or pioglitazone with high glucose and insulin. Cell viability and proliferation were evaluated using the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay and a bromodeoxyuridine incorporation assay, respectively, while cell cycle regulatory factors and oncogene expression were analyzed using western blotting. Metformin or pioglitazone suppressed cell viability concentration and time dependently, which was reversed by exposure to high glucose with or without insulin. Prolonged exposure to high glucose and insulin enhanced cyclin D, cyclin-dependent kinase 4 (Cdk4), and Cdk2 expression and suppressed cyclin-dependent kinase inhibitors p21 and p15/16 in HBlEpC cotreated with pioglitazone and metformin. Levels of tumor suppressor proteins p53 and cav-1 were downregulated while those of the oncogenic protein as c-Myc were upregulated under high glucose and insulin supplementation in HBlEpC cotreated with pioglitazone and metformin. Prolonged exposure to high glucose with or without insulin downregulated B cell lymphoma 2-associated X (Bax) and failed to enhance the expression of extracellular signal-regulated kinase (ERK) and p38 mitogen-activated protein kinase (p38MAPK) in drug-treated cells. These results suggest that hyperglycemic and insulinemic conditions promote cell cycle progression and oncogenic signaling in drug-treated bladder epithelial cells and uncontrolled hyperglycemia and hyperinsulinemia are probably greater cancer risk factors than diabetes drugs.
二甲双胍和吡格列酮是两种常用于治疗糖尿病的口服降糖药。最近的证据表明，这些药物可能导致膀胱癌。本研究探讨了二甲双胍和吡格列酮在 2 型糖尿病膀胱上皮细胞癌变中的分子机制。用人膀胱上皮细胞（HBlEpC）来源的细胞，用高糖和胰岛素处理二甲双胍或吡格列酮。用 3-(4,5-二甲基噻唑-2-基)-2,5-二苯基四唑溴盐（MTT）法和溴脱氧尿苷掺入法分别评估细胞活力和增殖，用 Western blot 分析细胞周期调节因子和癌基因表达。二甲双胍或吡格列酮浓度和时间依赖性地抑制细胞活力，而高糖加或不加胰岛素则可逆转这一作用。长时间暴露于高糖和胰岛素增强了 cyclin D、cyclin-dependent kinase 4 (Cdk4) 和 Cdk2 的表达，并抑制了 HBlEpC 中 cyclin-dependent kinase 抑制剂 p21 和 p15/16 的表达，同时 HBlEpC 用吡格列酮和二甲双胍共处理后。高糖加胰岛素可下调肿瘤抑制蛋白 p53 和 cav-1 的表达，而上调致癌蛋白 c-Myc 的表达。高糖加或不加胰岛素延长暴露时间可下调 B 细胞淋巴瘤 2 相关 X（Bax），但不能增强药物处理细胞中细胞外信号调节激酶（ERK）和丝裂原活化蛋白激酶 p38（p38MAPK）的表达。这些结果表明，高糖和胰岛素环境促进了药物处理的膀胱上皮细胞中的细胞周期进程和致癌信号转导，不受控制的高血糖和高胰岛素血症可能是比糖尿病药物更大的癌症危险因素。
