Abstract 99: Remodeling of calcium influx pathways in models of cancer associated fibroblasts in breast cancer

Calcium (Ca2+) influx pathways are remodelled in a variety of disease states, and alterations in the expression of specific Ca2+ permeable ion channels are a feature of some breast cancer subtypes. However, no studies have yet assessed possible alterations in Ca2+ influx pathways in the context of cancer-associated fibroblasts (CAFs), which are important in the tumor microenvironment and disease progression. The aim of this study was to identify possible changes in the nature of Ca2+ influx in CAFs and to define the role of Ca2+ signaling in the induction of breast CAFs. Levels of mRNA for voltage-gated and store-operated Ca2+ entry (SOCE) components were assessed in paired normal and CAF patient samples using qRT-PCR. The immortalised human mammary fibroblast cell line HMF3S, was treated with transforming growth factor beta (TGFβ) to induce a CAF phenotype (HMF3S-CAF) as confirmed by the expression of alpha smooth muscle actin (αSMA). HMF3S-CAF and HMF3S were also compared for expression of Ca2+ channels using qRT-PCR and functional store operated Ca2+ entry (SOCE) using a Fluorescence Imaging Plate Reader (FLIPR) Ca2+ assay. Specific Ca2+ channel subtypes were pharmacologically inhibited during TGFβ treatment to assess their role in CAF induction. Ca2+channel levels were altered in CAF patient samples compared to their paired controls and also in TGFβ-treated HMF3S cells. Voltage-gated Ca2+channel inhibitors significantly decreased TGFβ-mediated CAF activation. These data suggest that Ca2+ signaling is remodeled in CAFs and that the Ca2+ signal is important in breast CAF induction. Citation Format: Greg Monteith, Francisco Sadras, Teneale Stewart, Melanie Robitaille, Priyakshi Kalita-de Croft, Patsy Soon, Jodi Saunus, Sunil Lakhani, Sarah Roberts-Thomson. Remodeling of calcium influx pathways in models of cancer associated fibroblasts in breast cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 99.