Reprogramming ovarian and breast cancer cells into non-cancerous cells by low-dose metformin or SN-38 through FOXO3 activation

• Published in: Scientific reports Vol. 4; no. 1; p. 5810
• Main Authors: Hu, Theodore, Chung, Young Min, Guan, Michelle, Ma, Michael, Ma, Jessica, Berek, Jonathan S., Hu, Mickey C-T.
• Format: Journal Article
• Language: English
• Published: London Nature Publishing Group UK 24.07.2014; Nature Publishing Group
• Subjects: 13/1; 13/106; 13/31; 13/89; 13/95; 14/19; 631/67/1347; 631/67/1517/1709; 64/60; 692/699/67/1059/99; 82/80; 96/109; 96/34; 96/63; Active Transport, Cell Nucleus; Animals; Antidiabetics; Antineoplastic Agents, Phytogenic - pharmacology; Breast cancer; Breast Neoplasms - drug therapy; Breast Neoplasms - metabolism; Breast Neoplasms - pathology; c-Myc protein; Camptothecin - analogs & derivatives; Camptothecin - pharmacology; CD44 antigen; Cell culture; Cell Line, Tumor; Cell Proliferation - drug effects; Cell survival; Cell Survival - drug effects; Chemotherapy; Cytotoxicity; DNA Damage; Female; Forkhead Box Protein O3; Forkhead Transcription Factors - physiology; FOXO3 protein; Gene Expression Regulation, Neoplastic - drug effects; Gene Knockdown Techniques; Histones - metabolism; Humanities and Social Sciences; Irinotecan; Localization; Metformin; Metformin - pharmacology; Mice, Nude; multidisciplinary; Myc protein; Neoplastic Stem Cells - drug effects; Neoplastic Stem Cells - physiology; Oct-4 protein; Ovarian cancer; Ovarian Neoplasms - drug therapy; Ovarian Neoplasms - metabolism; Ovarian Neoplasms - pathology; Phosphorylation; Protein Processing, Post-Translational; Science; Side effects; Tumor Burden - drug effects; Xenograft Model Antitumor Assays
• ISSN: 2045-2322; 2045-2322
• DOI: 10.1038/srep05810

Cancer is a leading cause of death worldwide. Because the cytotoxic effects of conventional chemotherapies often harm normal tissue cells along with cancer cells, conventional chemotherapies cause many unwanted or intolerable side effects. Thus, there is an unmet medical need to establish a paradigm of chemotherapy-induced differentiation of cancer cells with tolerable side effects. Here we show that low-dose metformin or SN-38 inhibits cell growth or survival in ovarian and breast cancer cells and suppresses their tumor growth in vivo . Low-dose metformin or SN-38 increases FOXO3 nuclear localization as well as the amount of DNA damage markers and downregulates the expression of a cancer-stemness marker CD44 and other stemness markers, including Nanog, Oct-4 and c-Myc, in these cancer cells. This treatment also inhibits spheroid body-formation in 3-dimensional culture. In contrast, silencing FOXO3 diminishes all these cellular events when ovarian/breast cancer cells are treated with the mentioned drugs. These results suggest that low-dose metformin or SN-38 may reprogram these cancer cells into non-cancerous cells in a FOXO3-dependent manner and may allow patients to overcome these cancers with minimal side effects.