Cancers may arise from rare self-renewing tumor-initiating cells (T-IC). However, how T-IC self renewal, multipotent differentiation, and tumorigenicity are maintained remains obscure. Because miRNAs can regulate cell-fate decisions, we compared miRNA expression in self-renewing and differentiated cells from breast cancer lines and in breast T-IC (BT-IC) and non-BT-IC from 1 degrees breast cancers. let-7 miRNAs were markedly reduced in BT-IC and increased with differentiation. Infecting BT-IC with let-7-lentivirus reduced proliferation, mammosphere formation, and the proportion of undifferentiated cells in vitro and tumor formation and metastasis in NOD/SCID mice, while antagonizing let-7 by antisense oligonucleotides enhanced in vitro self renewal of non-T-IC. Increased let-7 paralleled reduced H-RAS and HMGA2, known let-7 targets. Silencing H-RAS in a BT-IC-enriched cell line reduced self renewal but had no effect on differentiation, while silencing HMGA2 enhanced differentiation but did not affect self renewal. Therefore let-7 regulates multiple BT-IC stem cell-like properties by silencing more than one target.
let-7 regulates self renewal and tumorigenicity of breast cancer cells.
F. Yu,H. Yao,Pengcheng Zhu,Xiaoqin Zhang,Qiuhui Pan,C. Gong,Yijun Huang,Xiaoqu Hu,F. Su,J. Lieberman,E. Song
Published 2007 in Cell
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- Publication year
2007
- Venue
Cell
- Publication date
2007-12-14
- Fields of study
Biology, Medicine
- Identifiers
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Semantic Scholar, PubMed
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