Abstract 4802: Human breast carcinoma-associated mesenchymal stem cells from primary breast cancer metastasis promote proliferation, invasion and mammosphere formation in breast cancer

Abstract

Abstract Background: Accumulating evidence suggests that mesenchymal stem cells (MSCs) are recruited to the tumor microenvironment; however controversy exists regarding their role in solid tumors. In this study, we identified the presence of carcinoma-associated MSCs (CA-MSCs) isolated from breast cancer metastasis to a human lymph node (LNM) and liver (LM). Methods: Tissue harvesting and culture: CA-MSCs were isolated from fresh samples of lymph nodes and liver breast cancer metastasis obtained from the operating room. A portion of each specimen was mechanically dissected and digested with collagenase. Red cells were lysed with ACK buffer and cell suspensions were cultured in Human Epithelial Medium and isolated adherent CA-MSCs were subculture in MSC medium for up to 12 passages for each experiment. Another portion of the tumor samples were subjected to IHC for H&E staining. Differentiation assays: For bone differentiation cells were plated in StemPro Osteogenesis differentiation or control medium and allowed to grow for 14 days, and then washed and stained with Alizarin Red S. For cartilage differentiation cells were pelleted and grown in 15 ml tubes for 21 days, immobilized in histogel and stained with Alizarin Blue. For adipose differentiation cells were plated in StemCell differentiation and control medium, after 21 days the cells were stained with 0.3% Oil Red O. Proliferation, invasion, mammosphere assays, cytokine array and RT-PCR for EMT signature were performed seeding the same number of cells and comparing the single culture of CA-MSCs with co-culture of CA-MSCs and a panel of breast cancer cells lines Results: CA-MSCs had spindle morphology, normal karyotype, were nontumorigenic, and possessed tri-lineage differentiation ability (osteoblast, adipocyte, and chondrocyte). When co-cultured with breast cancer cells, CA-MSCs promoted proliferation, invasion, and mammosphere formation, increased IL6 and IL8 secretion into the media, and induced a gene expression profile of EMT when compared to the single cultures. Conclusion: We successfully isolated and characterized CA-MSCs, confirming their presence in human breast metastasis. We found that they provide a favorable microenvironment for tumor cell growth, enhance mammosphere formation, and promote an EMT signature and invasion in breast cancer cells. Citation Format: Maria E. Gonzalez, Kathy A. Toy, Celina G. Kleer. Human breast carcinoma-associated mesenchymal stem cells from primary breast cancer metastasis promote proliferation, invasion and mammosphere formation in breast cancer. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 4802. doi:10.1158/1538-7445.AM2014-4802