Figure 3.

Carcinoma associated fibroblasts. Two CAF populations were identified through differential expression of CD146 in human breast tumors. CD146 is a stromal surface marker that defines fibroblast subtypes in the hematopoietic stem cell niche. In the context of breast cancer, CD146⁻ CAFs were shown to suppress ERα expression in MCF-7 cells, decreased sensitivity to estrogen, and increase resistance to tamoxifen. On the other hand, the presence of CD146⁺ CAFs promoted ERα expression and sustained estrogen-dependent proliferation and sensitivity to tamoxifen. PDGF receptors and ligands have recently been shown to actually modulate whether a tumor is luminal or basal and thus whether it may or not respond to endocrine therapy [Permission obtained from Springer Nature (73)].