Brodowska Katarzyna, Theodoropoulou Sofia, Meyer Zu Hörste Melissa, Paschalis Eleftherios I, Takeuchi Kimio, Scott Gordon, Ramsey David J, Kiernan Elizabeth, Hoang Mien, Cichy Joanna, Miller Joan W, Gragoudas Evangelos S, Vavvas Demetrios G
Retina Service, Angiogenesis Laboratory, Massachusetts Eye and Ear Infirmary, Department of Ophthalmology, Harvard Medical School, Boston, MA, USA.
Department of Immunology, Faculty of Biochemistry, Biophysics and Biotechnology, Jagiellonian University, Krakow, Poland.
Int J Oncol. 2014 Dec;45(6):2311-24. doi: 10.3892/ijo.2014.2650. Epub 2014 Sep 11.
Recent studies suggest that the anti-diabetic drug metformin may reduce the risk of cancer and have anti-proliferative effects for some but not all cancers. In this study, we examined the effects of metformin on human retinoblastoma cell proliferation in vitro and in vivo. Two different human retinoblastoma cell lines (Y79, WERI) were treated with metformin in vitro and xenografts of Y79 cells were established in nu/nu immune-deficient mice and used to assess the effects of pharmacological levels of metformin in vivo. Metformin inhibited proliferation of the retinoblastoma cells in vitro. Similar to other studies, high concentrations of metformin (mM) blocked the cell cycle in G0‑G1, indicated by a strong decrease of G1 cyclins, especially cyclin D, cyclin-dependent kinases (4 and 6), and flow cytometry assessment of the cell cycle. This was associated with activation of AMPK, inhibition of the mTOR pathways and autophagy marker LC3B. However, metformin failed to suppress growth of xenografted tumors of Y79 human retinoblastoma cells in nu/nu mice, even when treated with a maximally tolerated dose level achieved in human patients. In conclusion, suprapharmacological levels (mM) of metformin, well above those tolerated in vivo, inhibited the proliferation of retinoblastoma cells in vitro. However, physiological levels of metformin, such as seen in the clinical setting, did not affect the growth of retinoblastoma cells in vitro or in vivo. This suggests that the potential beneficial effects of metformin seen in epidemiological studies may be limited to specific tumor types or be related to indirect effects/mechanisms not observed under acute laboratory conditions.
近期研究表明，抗糖尿病药物二甲双胍可能降低癌症风险，且对某些（而非所有）癌症具有抗增殖作用。在本研究中，我们检测了二甲双胍对人视网膜母细胞瘤细胞在体外和体内增殖的影响。两种不同的人视网膜母细胞瘤细胞系（Y79、WERI）在体外接受二甲双胍处理，Y79细胞的异种移植瘤在无胸腺/无脾免疫缺陷小鼠中建立，用于评估二甲双胍药理水平在体内的作用。二甲双胍在体外抑制视网膜母细胞瘤细胞的增殖。与其他研究相似，高浓度的二甲双胍（毫摩尔）使细胞周期停滞在G0 - G1期，表现为G1期细胞周期蛋白尤其是细胞周期蛋白D、细胞周期蛋白依赖性激酶（4和6）显著减少，以及通过流式细胞术对细胞周期进行评估。这与AMPK的激活、mTOR通路的抑制以及自噬标志物LC3B有关。然而，即使给予在人类患者中所能达到的最大耐受剂量水平，二甲双胍仍未能抑制无胸腺/无脾小鼠中Y79人视网膜母细胞瘤细胞异种移植瘤的生长。总之，超药理水平（毫摩尔）的二甲双胍，远高于体内耐受水平，在体外抑制了视网膜母细胞瘤细胞的增殖。然而，临床环境中所见的生理水平的二甲双胍，在体外或体内均未影响视网膜母细胞瘤细胞的生长。这表明在流行病学研究中观察到的二甲双胍潜在有益作用可能仅限于特定肿瘤类型，或与在急性实验室条件下未观察到的间接效应/机制有关。
