LAUSR

Calcium is a key regulator of a variety of pathways important in breast cancer progression, including those involved in cell proliferation and invasiveness. Calcium signaling is implicated in processes relevant to the breast cancer tumor microenvironment and altered calcium influx is a feature of cancer associated fibroblasts. In these studies, simultaneous use of genetically encoded calcium indicators with distinct fluorescence spectral properties (GCaMP6m or JRCaMP1b), were used to explore the cross-talk between breast cancer cells and fibroblasts via calcium signaling and changes in different cellular compartments. HMF3S human fibroblast cells co-cultured with breast cancer cells expressing GCaMP6m or JRCaMP1b were assessed in 2D and 3D co-culture using automated epi-fluorescence or confocal microscopy. Mitochondrial calcium levels were assessed using targeted GCaMP6m (2mtGCaMP6m) in HMF3S cells expressing JRCaMP1b. Results showed distinct spatial and temporal changes in free calcium levels between both fibroblasts and breast cancer cells and the mitochondria and cytosol during activation. These methodological advances provide an opportunity to better understand calcium signaling in cancer associated fibroblasts. These techniques will also help identify the calcium channels and pumps that could be targeted to manipulate the breast cancer tumor microenvironment to inhibit pathways important in breast cancer progression. Citation Format: Alice H. Bong, Krystyna A. Gieniec, Francisco Sadras, Mélanie Robitaille, Sarah J. Roberts-Thomson, Felicity M. Davis, Gregory R. Monteith. Calcium signalling and the breast cancer microenvironment. [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 3629.