title: Metformin represses self-renewal of the human breast carcinoma stem cells via inhibition of estrogen receptor-mediated OCT4 expression.
abstract: Metformin, a Type II diabetic treatment drug, which inhibits transcription of gluconeogenesis genes, has recently been shown to lower the risk of some diabetes-related tumors, including breast cancer. Recently, "cancer stem cells" have been demonstrated to sustain the growth of tumors and are resistant to therapy. To test the hypothesis that metformin might be reducing the risk to breast cancers, the human breast carcinoma cell line, MCF-7, grown in 3-dimensional mammospheres which represent human breast cancer stem cell population, were treated with various known and suspected breast cancer chemicals with and without non-cytotoxic concentrations of metformin. Using OCT4 expression as a marker for the cancer stem cells, the number and size were measured in these cells. Results demonstrated that TCDD (100 nM) and bisphenol A (10 µM) increased the number and size of the mammospheres, as did estrogen (10 nM E2). By monitoring a cancer stem cell marker, OCT4, the stimulation by these chemicals was correlated with the increased expression of OCT4. On the other hand, metformin at 1 and 10 mM concentration dramatically reduced the size and number of mammospheres. Results also demonstrated the metformin reduced the expression of OCT4 in E2 & TCDD mammospheres but not in the bisphenol A mammospheres, suggesting different mechanisms of action of the bisphenol A on human breast carcinoma cells. In addition, these results support the use of 3-dimensional human breast cancer stem cells as a means to screen for potential human breast tumor promoters and breast chemopreventive and chemotherapeutic agents.
authors: Department of Veterinary Public Health, College of Veterinary Medicine, Adult Stem Cell Research Center, Seoul National University, Seoul, Republic of Korea.
authors: Ji-Won
authors: JW
authors: Jung
authors: Sang-Bum
authors: SB
authors: Park
authors: Soo-Jin
authors: SJ
authors: Lee
authors: Min-Soo
authors: MS
authors: Seo
authors: James E
authors: JE
authors: Trosko
authors: Kyung-Sun
authors: KS
authors: Kang
mesh_terms: D000975:Antioxidants / Q000494:pharmacology; D001943:Breast Neoplasms / Q000235:genetics / Q000473:pathology*; D049109:Cell Proliferation / Q000187:drug effects; D004958:Estradiol / Q000494:pharmacology; D005260:Female; D005434:Flow Cytometry; D006801:Humans; D008687:Metformin / Q000494:pharmacology*; D014411:Neoplastic Stem Cells / Q000187:drug effects / Q000378:metabolism / Q000473:pathology*; D050814:Octamer Transcription Factor-3 / Q000235:genetics / Q000378:metabolism*; D010637:Phenolsulfonphthalein / Q000378:metabolism; D011401:Promoter Regions, Genetic / Q000235:genetics; D011960:Receptors, Estrogen / Q000037:antagonists & inhibitors* / Q000378:metabolism; D020218:Response Elements / Q000235:genetics; D018874:Spheroids, Cellular / Q000187:drug effects / Q000378:metabolism / Q000473:pathology; D014407:Tumor Cells, Cultured
chemical_list: D000975:Antioxidants; D050814:Octamer Transcription Factor-3; C494173:POU5F1 protein, human; D011960:Receptors, Estrogen; D004958:Estradiol; D008687:Metformin; D010637:Phenolsulfonphthalein