Altered Calcium Influx Pathways in Cancer-Associated Fibroblasts.

Patsy S Soon,Priyakshi Kalita-De Croft,Jodi M Saunus,Mélanie Robitaille,Teneale A Stewart,Sunil R Lakhani,Francisco Sadras,Sarah J Roberts-Thomson,Amelia A Peters,Gregory R Monteith

doi:10.3390/biomedicines9060680

Abstract

Cancer-associated fibroblasts (CAFs) represent an important component of the tumour microenvironment and are implicated in disease progression. Two outstanding questions in cancer biology are how CAFs arise and how they might be targeted therapeutically. The calcium signal also has an important role in tumorigenesis. To date, the role of calcium signalling pathways in the induction of the CAF phenotype remains unexplored. A CAF model was generated through exogenous transforming growth factor beta 1 (TGFβ1) stimulation of the normal human mammary fibroblast cell line, HMF3S (HMF3S-CAF), and changes in calcium signalling were investigated. Functional changes in HMF3S-CAF calcium signalling pathways were assessed using a fluorescent indicator, gene expression, gene-silencing and pharmacological approaches. HMF3S-CAF cells demonstrated functionally altered calcium influx pathways with reduced store-operated calcium entry. In support of a calcium signalling switch, two voltage-gated calcium channel (VGCC) family members, CaV1.2 and CaV3.2, were upregulated in HMF3S-CAFs and a subset of patient-derived breast CAFs. Both siRNA-mediated silencing and pharmacological inhibition of CaV1.2 or CaV3.2 significantly impaired CAF activation in HMF3S cells. Our findings show that VGCCs contribute to TGFβ1-mediated induction of HMF3S-CAF cells and both transcriptional interference and pharmacological antagonism of CaV1.2 and CaV3.2 inhibit CAF induction. This suggests a potential therapeutic role for targeting calcium signalling in breast CAFs.

Highlights

We show that two voltage-gated calcium channel (VGCC) family members, CaV 1.2 and CaV 3.2, are upregulated in our in vitro cancer-associated fibroblasts (CAFs) model as well as in a subset of patient-derived breast
Vancauwenberghe et al [44] showed that overexpression of a mutant isoform of the Ca2+ permeable ion channel transient receptor potential cation channel subfamily A member 1 (TRPA1) in CAFs promotes resistance to resveratrol-mediated apoptosis in prostate cancer cells, and that this occurs in a calciumdependent manner
Our studies focused on identifying whether breast CAFs display alterations in store-operated calcium entry (SOCE) in vitro, and if inhibition of specific Ca2+ influx pathways can modify the induction of a CAF phenotype

Summary

Introduction

It is increasingly appreciated that the tumour microenvironment (TME) is an active player in carcinogenesis [1]. Fibroblasts are the major cell type of the breast TME and are highly plastic [2]. Normal fibroblasts (NFs) are typically tumour-suppressive but can be transformed into tumour-promoting cancer-associated fibroblasts (CAFs) through a series of phenotypic changes [3]. CAFs are a highly diverse population that can be derived from adipocytes, immune, and endothelial cells. In all of these scenarios there are significant cellular and gene expression changes [4]. A variety of CAF inducers such as Biomedicines 2021, 9, 680.

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