MCL-1 as a molecular switch between myofibroblastic and pro-angiogenic features of breast cancer-associated fibroblasts

ABSTRACT: Breast cancer-associated-fibroblasts (bCAFs) consist of two pro-tumoral populations: inflammatory CAFs (iCAF) releasing pro-inflammatory cytokines, and myofibroblastic CAFs (myCAF) known for their extensive production of extracellular matrix proteins and immunosuppressive features. We have previously shown that targeting the anti-apoptotic protein MCL-1 in primary culture of bCAFs directly derived from human samples reduces their myofibroblastic characteristics linked to actomyosin cytoskeleton disorganization and mitochondrial fragmentation. In this study, we explore the involvement of this protein in phenotypic differentiation and plasticity of bCAFs. Single-cell RNA-sequencing analysis reveals a shift from wound-myCAF to IL-iCAFs phenotype expressing genes involved in inflammation like IL-8, IL-1β, CXCL1, CXCL3, CCL2 and in angiogenesis like VEGF after MCL-1 gene silencing in bCAFs. In vitro, targeting of MCL-1 in bCAFs induces an increase of VEGF secretion associated with enhanced endothelial cell tubulogenesis. In ovo, using chicken chorioallantoic membrane model, we engrafted breast cancer cells and bCAFs to study vascularization. Our data suggest that a low level of MCL-1 expression in bCAF is associated with greater peritumoral vascular density in a VEGF-dependent manner. Furthermore, chemotherapy that downregulated MCL-1 expression in bCAFs is accompanied by the same pro-angiogenic effects. Mechanistically, pharmacological inhibition of MCL-1 promotes mitochondrial outer membrane permeabilization and NF-κB activation in cGAS-STING independent-manner. Blockage of NF-κB activity with an IKKβ inhibitor counteracts VEGF and pro-inflammatory factors transcription induced by MCL-1 inhibition in bCAFs. Our findings highlight a novel role for MCL-1 in regulating the pro-angiogenic properties of bCAFs, and provide new elements for characterizing the different bCAFs subpopulations.

INSTRUMENT(S):

ORGANISM(S): Homo Sapiens (human)

TISSUE(S): Cell Culture, Fibroblast

DISEASE(S): Breast Cancer

SUBMITTER: François Guillonneau  

LAB HEAD: Frédérique Souazé

PROVIDER: PXD058906 | Pride | 2025-08-14

REPOSITORIES: Pride