Abstract B22: Analysis of Lgr5-positive cells in mouse mammary gland

Abstract

Abstract Lgr5 has been identified as a stem cell marker in multiple adult tissues, and individual Lgr5+ mammary epithelial cells are capable of regenerating mouse mammary glands in transplantation assays. Here we investigated the proliferation and differentiation capabilities of murine mammary Lgr5+ cells in vitro, and their distribution in mouse mammary glands in vivo. Equal numbers of sorted Lgr5+ and Lgr5- epithelial cells were cultured in Matrigel to evaluate their stem-like properties in vitro. Compared with Lgr5- cells, Lgr5+ cells were more efficient at generating organoids in 3D culture, and the Lgr5+ cell-derived organoids grew to a larger size. Moreover, Lgr5+ cell-derived organoids survived repeated passaging and contained cells of both luminal and basal lineages, as indicated by keratin marker expression. Incidence of Lgr5+ cells in organoids was confirmed by in situ hybridization. These studies indicate that Lgr5+ cells retain the self-renewal and differentiation capabilities of stem cells ex vivo. The in vivo distribution of Lgr5+ cells was investigated using X-Gal-stained mammary glands from Lgr5-lacZ reporter mice ranging from 5 to 32 weeks old. In both adolescent and adult mice, we observed a graded distribution of Lgr5+ cells with greater abundance in the nipple-proximal (ventral) ducts than in the lymph-node proximal central region, and fewest Lgr5+ cells in the distal (dorsal) region of the glands. Lgr5+ cells from all mammary gland regions appeared capable of yielding organoids in culture. These results corroborate in organoid culture the known stem-like properties of Lgr5+ cells defined in intact mouse mammary gland. [Supported by NIH grant CA186981 and the China Scholarship Council] Citation Format: Lixing Zhang, Louise Howe, Richard Kolesnick, Anthony Brown. Analysis of Lgr5-positive cells in mouse mammary gland. [abstract]. In: Proceedings of the AACR Special Conference: Developmental Biology and Cancer; Nov 30-Dec 3, 2015; Boston, MA. Philadelphia (PA): AACR; Mol Cancer Res 2016;14(4_Suppl):Abstract nr B22.