Abstract B45: De novo generation of highly aggressive human breast tumors by rapid serial passaging of oncogene-transduced starting populations of purified normal cells

Abstract

Abstract Human breast cancers are clonal outgrowths that have diversified genetically and biologically by the time they are clinically evident. However, early events that predicate malignant transformation of normal human mammary epithelial cells and the importance of the specific cell type to first be altered has remained elusive. We have developed an in vivo system that allows analysis of the initial steps of tumorigenesis from defined subsets of normal human mammary cells within 8 weeks using a single (KRASG12D) or multiple oncogenes. Using a protocol in which we first isolate biologically, transcriptionally and phenotypically different human mammary cell types by FACS using EpCAM and CD49f or CD10 as distinguishing markers, and then transduce the cells with lentiviral constructs, and immediately transplant them into highly immunodeficient NOD/RAG1-/-IL2rγ-/- (NRG) female mice, we have found that invasive ductal carcinomas expressing a variety of basal and luminal-associated markers (such as CK5, CK8/18, EGFR and MUC1) can be obtained at high frequency from purified starting populations of both basal cells and luminal progenitors within 8 weeks. Many tumours could be passaged both in vivo and under multiple conditions in vitro (on collagen, in suspension “mammopshere” culture or 3D matrigel cultures). After only 4passages in vivo, an aggressive tumor cell line that is tumorigenic within 6 weeks in vivo at unit efficiency has emerged. Intravenous injections shown that these cells can colonize multiple organs including the lung, kidney and spleen. Molecular characterization of these aggressive tumors has established that they are EpCAM+ and CD44+. Additional examples of de novo tumors able to be serially passaged are now being characterized. This new tumorigenesis model will allow us to compare the sequential changes that accompany and underlie the full process of malignant progression and should thus enable key molecular determinants that drive cancer initiation and progression to be identified. Citation Format: Sylvain Lefort, Davide Pellacani, Long Nguyen, Connie J. Eaves. De novo generation of highly aggressive human breast tumors by rapid serial passaging of oncogene-transduced starting populations of purified normal cells. [abstract]. In: Proceedings of the AACR Special Conference on Advances in Breast Cancer Research; Oct 17-20, 2015; Bellevue, WA. Philadelphia (PA): AACR; Mol Cancer Res 2016;14(2_Suppl):Abstract nr B45.