Abstract 1896: Soluble lung-derived selectins promote breast cancer cell migration

Ninety percent of all breast cancer-related deaths are attributed to metastasis, as current therapies are largely non-curative in the metastatic setting. One of the most common sites of breast cancer metastasis is the lung. Previous work from our lab has demonstrated that there are over 70 soluble factors produced by murine lung tissue, many of which have been associated with cancer cell growth, migration, invasion and metastasis. However, the relative contribution of each individual factor in enhancing the metastatic behavior of breast cancer cells has not been examined in detail. Three of the identified soluble lung-derived proteins are E-, L- and P-selectin, and these were the focus of the current study. The selectins are a family of glycoproteins with known physiological roles in vascular/immune cell migration, and soluble selectins have been clinically observed to be elevated in the sera of cancer patients. We hypothesized that soluble lung-derived selectins enhance the metastatic behavior of breast cancer cells. We used a 2D ex vivo model of the soluble lung microenvironment, generated by isolating conditioned media from dissociated healthy murine lung. E-, L- and P-selectin were then individually immunodepleted from the lung-conditioned media (lung-CM) and the subsequent functional effect on breast cancer cell migration and proliferation was assessed using transwell migration and BrdU incorporation assays, respectively. MDA-MB-231 and SUM149PT human breast cancer cells demonstrated significantly enhanced cell migration toward lung-CM relative to basal media, and this migration was significantly reduced when E-, L- or P-selectin were depleted (p 0.05). Ongoing studies are aimed at elucidating the pathways through which soluble lung-derived selectins exert their pro-migratory function. If these results implicate a common receptor and downstream signalling pathways for all three selectins, these ligand-receptor interactions may have value as potential therapeutic targets for the prevention of pulmonary metastasis in breast cancer patients. Citation Format: Sami U. Khan, Jenny E. Chu, Ying Xia, Alison L. Allan. Soluble lung-derived selectins promote breast cancer cell migration [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 1896. doi:10.1158/1538-7445.AM2017-1896