Abstract 173: Adipocytes-derived collagen reorganization in microenvironment promotes breast cancer progression

Abstract Purposes Breast cancer cells recruit surrounding stromal cells, such as cancer-associated fibroblasts (CAFs), to reorganize collagen and promote tumor metastasis. Adipocytes are the most abundant stromal partners in breast tissue, whether cancer-associated adipocytes (CAAs) involve in the collagen reorganization and ultimately promoting metastasis of breast cancer is still unknown. In this study, we seek to understand whether adipocytes involve in the extracellular matrix collagen reorganization in breast cancer and its underline mechanism. Methodology In vitro mature adipocytes and breast cancer transwell co-culture model and orthotopic xenograft mouse model of human breast tumor formation in vivo were used to study the crosstalk between adipocytes and breast cancer cells, and then using a combination of proteomics, database analysis and clinical breast cancer samples analysis to study the mechanism mediated adipocytes-derived collagen reorganization. Results Here, we found that CAAs co-cultured with breast cancer cells increased the linearly aligned type I collagen fibers deposition in vitro and in vivo, which accompanied with increasing collagen lysyl hydroxylation 2 (LH2) and lysyl oxidase (LOX) expression. Breast cancer cells migrated orderly along the CAAs-derived collagen, while randomly migrated through the mature adipocyte-derived collagen. Simultaneously, clinical breast cancer samples analysis showed LH2 was high expression in the areas where cancer cells infiltrated into fatty tissue, which accompanied with poor prognosis. It is well-known that interaction between adipocytes and cancer altered the secretion of cytokines. In the present study, proteomics analysis showed that IL-6, MIF-1, TECK, MCP-1, PAI-1, IGFBP-1, TIMP1 and TIMP2 are highly secreted in adipocytes-breast cancer system. And using agonist or antagonist of these cytokines showed that these cytokines might involve in the reorganization of adipocyte-derived collagen. Mechanistic investigations demonstrated PI3K/AKT pathway and JAK/STAT3 signaling pathway involved in the rearrangement of adipocyte-derived collagen, which mediated by promoting forkhead-box(FOX) and phosphorylation STAT3(p-STAT3) translocate to the nucleus, respectively. Moreover, FOX and STAT3-dependent induction of LH2 expression further potentiated the adipocytes-derived collagen reorganization, which thus promoting breast cancer metastasis. Conclusion Collectively, our findings reveal new insights underlying increased breast cancer progression and offer new opportunities for stromal-targeted therapies in breast cancer. Citation Format: Wei Xiaohui, He Jinyong, Li Sijing, Yuan Shengtao, Sun Li. Adipocytes-derived collagen reorganization in microenvironment promotes breast cancer progression [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 173.