Abstract 4142: Proteomics analysis of breast cancer cell-specific proteins that are transferred to immune cells via trogocytosis

Abstract

Abstract We previously reported that HER2 is transferred from HER2 overexpressing breast cancer cells to CD14+ monocytes via trastuzumab dependent trogocytosis (Suzuki et al. BMC cancer 2015) and EGFR of MDA-MB-231 (triple negative human breast cancer cell line) is also transferred to immune cells via trogocytosis and those immune cells express EGFR on the cell surface without therapeutic antibody administration (AACR 2015 #2349). There are several reports that suggest that trogocytosis might act to stimulate immunological tolerance or immune effector cell activation, however its immunological roles still remain unclear. Therefore, in order to clarify the role of trogocytosis, we study the profile of proteins that potentially are transferred from cancer cell to immune cell via trogocytosis. Human triple negative breast cancer cell line, MDA-MB-231 that was cultured with the medium containing arginine labeled with 13C instead of normal 12C (SILAC method, ThermoFisher Scientific) was co-cultured with human peripheral blood mononuclear cell (PBMC) that was cultured with normal medium. The cell mixture was labeled with CD45+ magnetic beads and CD45+ cell (PBMC) and CD45- cell (MDA-MB-231) were separated by MACS cell separation kit (Miltenyi Biotec). Proteins of PBMC that were passed the trogocytosis were resolved on SDS-PAGE and LC-MS/MS was carried out to identify the cancer specific trogocytosed proteins in PBMC by SILAC method. We found that proteins with higher H/L ratio were included in many of cytoskeletal proteins and interestingly mitochondrial metabolism related proteins of cancer cells were also detected in PBMC. Those up-regulated proteins in PBMC were reduced in MDA-MB-231. The findings suggested that the role of trogocytosis of PBMC on breast cancer cell might be involved in metabolisms of both cancer cell and immune cell. Thus, we are exploring the effect of trogocytosis on cancer cell metabolisms especially on mitochondrial related metabolism that could be reduced by immune cell trogocytosis and also on metabolism of immune cells themselves that capture the cancer cell proteins via trogocytosis. Citation Format: Eiji Suzuki, Masashi Inoue, Shinji Ito, Junko Satoh, Kosuke Kawaguchi, Ayane Yamaguchi, Moe Tsuda, Masakazu Toi. Proteomics analysis of breast cancer cell-specific proteins that are transferred to immune cells via trogocytosis. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 4142.