MicroRNA expression patterns are often characteristic of specific cell types. The mouse mammary epithelial cell line, Comma-1D, contains a sub-population of self-renewing stem cells which can reconstitute the mammary gland. Hannon has purified this population and determined its microRNA signature. Several microRNAs, including miR-205 and miR-22, are highly expressed in mammary stem cells, while others, including let-7 and miR-93, are depleted. Let-7 sensors can be used to prospectively enrich self-renewing populations, and enforced let-7 expression induces loss of self-renewing cells from mixed cultures. Remarkably, tumor-initiating cells, purified from human cancer cell lines, share the microRNA signature of mammary stem cells.
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Czech B, Malone CD, Zhou R, Stark A, Schlingeheyde C, Dus M, Perrimon N, Kellis M, Wohlschlegel JA, Sachidanandam R, Hannon GJ, Brennecke J. An endogenous small interfering RNA pathway in Drosophila. Nature. 2008 Jun 5;453(7196):798-802. Epub 2008 May 7.
Ibarra I, Erlich Y, Muthuswamy SK, Sachidanandam R, Hannon GJ. A role for microRNAs in maintenance of mouse mammary epithelial progenitor cells. Genes Dev. 2007 Dec 15;21(24):3238-43.