Zordoky Beshay N M, Bark Diana, Soltys Carrie L, Sung Miranda M, Dyck Jason R B
Cardiovascular Research Centre, Faculty of Medicine and Dentistry, University of Alberta, Edmonton, Alberta, Canada.
Cardiovascular Research Centre, Faculty of Medicine and Dentistry, University of Alberta, Edmonton, Alberta, Canada.
Biochim Biophys Acta. 2014 Jun;1840(6):1943-57. doi: 10.1016/j.bbagen.2014.01.023. Epub 2014 Jan 23.
Metformin has been shown to have a strong anti-proliferative effect in many breast cancer cell lines, mainly due to the activation of the energy sensing kinase, AMP-activated protein kinase (AMPK). MDA-MB-231 cells are aggressive and invasive breast cancer cells that are known to be resistant to several anti-cancer agents as well as to the anti-proliferative effect of metformin. As metformin is a glucose lowering drug, we hypothesized that normoglycemia will sensitize MDA-MB-231 cells to the anti-proliferative effect of metformin.
MDA-MB-231 cells were treated with increasing metformin concentrations in hyperglycemic or normoglycemic conditions. The growth inhibitory effect of metformin was assessed by MTT assay. The expression of several proteins involved in cell proliferation was measured by Western blotting.
In agreement with previous studies, treatment with metformin did not inhibit the growth of MDA-MB-231 cells cultured in hyperglycemic conditions. However, metformin significantly inhibited MDA-MB-231 growth when the cells were cultured in normoglycemic conditions. In addition, we show that metformin-treatment of MDA-MB-231 cells cultured in normoglycemic conditions and not in hyperglycemic conditions caused a striking activation of AMPK, and an AMPK-dependent inhibition of multiple molecular signaling pathways known to control protein synthesis and cell proliferation.
Our data show that normoglycemia sensitizes the triple negative MDA-MB-231 breast cancer cells to the anti-proliferative effect of metformin through an AMPK-dependent mechanism.
These findings suggest that tight normoglycemic control may enhance the anti-proliferative effect of metformin in diabetic cancer patients.
二甲双胍已被证明在许多乳腺癌细胞系中具有强大的抗增殖作用，主要是由于能量感应激酶——AMP激活的蛋白激酶（AMPK）的激活。MDA-MB-231细胞是侵袭性乳腺癌细胞，已知对多种抗癌药物以及二甲双胍的抗增殖作用具有抗性。由于二甲双胍是一种降血糖药物，我们推测正常血糖水平会使MDA-MB-231细胞对二甲双胍的抗增殖作用敏感。
在高血糖或正常血糖条件下，用递增浓度的二甲双胍处理MDA-MB-231细胞。通过MTT法评估二甲双胍的生长抑制作用。通过蛋白质印迹法检测参与细胞增殖的几种蛋白质的表达。
与先前的研究一致，在高血糖条件下培养的MDA-MB-231细胞用二甲双胍处理并未抑制其生长。然而，当细胞在正常血糖条件下培养时，二甲双胍显著抑制了MDA-MB-231细胞的生长。此外，我们发现，在正常血糖而非高血糖条件下培养的MDA-MB-231细胞用二甲双胍处理会导致AMPK显著激活，以及对已知控制蛋白质合成和细胞增殖的多种分子信号通路的AMPK依赖性抑制。
我们的数据表明，正常血糖通过AMPK依赖性机制使三阴性MDA-MB-231乳腺癌细胞对二甲双胍的抗增殖作用敏感。
这些发现表明，严格控制正常血糖水平可能会增强二甲双胍对糖尿病癌症患者的抗增殖作用。
