The CXCL12/CXCR4 axis in breast cancer-associated fibroblasts: a transcriptome analysis and systematic literature review

Background Cancer-associated fibroblasts (CAFs) represent a pivotal component of the breast cancer microenvironment. In a paracrine model, CAFs secreted the chemokine CXCL12 (SDF-1α), which bound to CXCR4 and activated the PI3K/AKT and MAPK signaling pathways, stimulating their migration and invasion. TGF-β1 induces myofibroblast differentiation of CAFs by acting through the TGFBR2/ALK5 receptor complex and phosphorylating SMAD2/3, thereby increasing the expression of ACTA2 and FAP. An autocrine loop has been demonstrated in CAF, whereby TGF-β1, via SMAD3, induces the transcription of CXCR4, and subsequently, CXCR4, by binding to the same cell, maintains the myofibroblast phenotype. However, a systematic comparison of paracrine and autocrine variants has not yet been conducted in the context of CAF subtypes. Methods A secondary analysis of 101 bulk RNA-seq samples was performed, with classification into healthNF, riskNF, cancerNF, and CAF S1-S4 using correlation analysis (Spearman), differential expression (DESeq, FDR