Abstract 3371: Periostin secreted by breast cancer cells inhibits macrophage phagocytosis and adhesion to fibronectin

Abstract

Abstract Interactions between cancer cells and immune cells are critical to the development of breast cancer metastases. We have previously shown that breast cancer cells secrete periostin, an extracellular matrix protein implicated in tumor progression. Here we evaluated 1) the effect of macrophage secretions on 4T1 breast cancer cell production of periostin and 2) the effect of periostin on key macrophage functions. In vitro, periostin secretion by highly metastastic 4T1 mammary cancer cells was investigated by ELISA. Following a 48-hour incubation with conditioned media obtained from J774A-1 monocyte cells, 4T1 cells secreted significantly higher periostin concentrations (p<0.05). Next, the effect of prolonged incubation with periostin on proliferation, adhesion and phagocytosis of macrophages was investigated using mouse J774A-1 and RAW264.7 monocyte cells and mouse primary bone marrow macrophages. In the conditions tested, periostin did not affect macrophage proliferation. Incubation with periostin significantly decreased macrophage adhesion to fibronectin-coated vessels (p<0.05). Incubation with periostin also significantly inhibited macrophage phagocytosis of polymer beads (p<0.05). Together, these observations indicate that the secretion of periostin by 4T1 cells is, in part, stimulated through paracrine communication with macrophages, and that periostin inhibits both macrophage adhesion and phagocytosis. Citation Format: Michelle M. Coleman, Rachel S. Helms, Didier Dreau. Periostin secreted by breast cancer cells inhibits macrophage phagocytosis and adhesion to fibronectin. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 3371. doi:10.1158/1538-7445.AM2015-3371