cancer-associated fibroblast
cancer-associated fibroblast
Overview
Cancer-associated fibroblasts (CAFs) are a heterogeneous population of activated stromal cells that constitute a major non-malignant component of the tumor microenvironment (TME). Derived from normal tissue fibroblasts, mesenchymal stem cell, and other precursor populations, CAFs undergo phenotypic reprogramming in response to signals from neighboring tumor cells, leading to a persistently activated state characterized by the expression of markers such as alpha-smooth muscle actin (α-SMA), fibroblast activation protein (Fap), and periostin (POSTN). Unlike quiescent fibroblasts, CAFs are metabolically and secretorily hyperactive, producing abundant extracellular matrix (ECM) components—including collagen and fibronectin—as well as a wide repertoire of growth factors, cytokines, and exosomes that collectively remodel the tumor stroma into a biochemically and physically hostile microenvironment. This dense, desmoplastic stroma is a hallmark of several solid tumor types and serves as a major barrier to drug delivery, immune infiltration, and therapeutic efficacy.
The biological significance of CAFs extends well beyond passive structural support. CAFs are central architects of immunosuppression, actively excluding cytotoxic T cells and natural killer (NK) cells from tumor nests while promoting the accumulation of immunosuppressive cell types such as tumor-associated macrophages. Through paracrine signaling—including secretion of fibroblast growth factors (FGFs), transforming growth factor-beta (TGF-β), and metabolic intermediates such as DL-lactic acid—CAFs reprogram both malignant and immune cells to favor tumor progression, metastasis, and resistance to therapy. Their functional and transcriptional heterogeneity, now increasingly resolved at single-cell resolution, has revealed distinct CAF subtypes with divergent roles in ECM remodeling, immune regulation, and epithelial-mesenchymal transition (EMT), making them a compelling and multifaceted target in oncology.
Focus of Latest Publications
Recent publications have focused on cancer-associated fibroblasts (CAFs) as dynamic components of the tumor microenvironment and as therapeutic targets in multiple solid tumors. Several studies examined how CAF depletion or reprogramming alters stromal and immune contexts, including single-cell RNA-sequencing analysis after Fap+ fibroblast depletion and a Fap-CD3 T-cell engager study that reported emergence of a mixed CAF population associated with limited therapeutic efficacy. Other work integrated ligand-receptor interactions, multi-omics data, and histopathological imaging to better characterize the CAF microenvironment in pancreatic adenocarcinoma, underscoring the importance of CAF-centered signaling networks in prognostic modeling and tumor ecology.
A recurring theme is that CAFs can promote treatment resistance and immune evasion through metabolic and signaling reprogramming. In hepatocellular carcinoma, WNK4 was transferred from tumor cells to CAFs via extracellular exosomes, where it reprogrammed cysteine metabolism through a WNK4-HMGB1-p53 axis and increased cystathionine gamma-lyase expression, contributing to tumor progression and anti-PD-1 resistance. In triple-negative breast cancer, SDC1 in CAFs stabilized ENO1, promoted aerobic glycolysis and lactate accumulation, and generated a lactate-rich microenvironment that enhanced tumor stemness while impairing natural killer cell and cytotoxic T cell function, thereby driving radioresistance. In colorectal cancer, a multi-omics study specifically investigated INHBA+ CAFs and their role in epithelial-mesenchymal transition and immune suppression.
Other studies explored strategies to therapeutically target CAFs or their stromal effects. A microwave ablation sensitizer that combined a biomimetic cancer cell-CAF membrane with a nitric oxide donor was designed to inhibit CAF activation, degrade dense extracellular matrix, improve immune cell infiltration, and reverse CAF-mediated immunosuppression in liver cancer. A carrier-free nanoreshaper using quercetin, manganese ions, and the Indoleamine 2,3-dioxygenase 1 inhibitor NLG919 was reported to normalize CAFs, reduce extracellular matrix deposition, and enhance anti-PD-L1 therapy. Biomimetic lipid nanoparticles were also shown to preferentially interact with functionally validated CAFs, supporting dual targeting of tumor and stromal cells in desmoplastic breast cancer.
Clinical and translational studies further linked CAF abundance or CAF-directed interventions to outcome and metastasis. In oral squamous cell carcinoma, high CAF infiltration at the invasion front was associated with poor overall survival and was identified as one of the most useful immuno-oncology markers for prognosis. In lung squamous cell carcinoma, the PI3Kα inhibitor CYH33 reduced CAF infiltration, suppressed CAF trans-differentiation and proliferation, lowered hepatocyte growth factor secretion, and attenuated metastasis. Together, these publications portray CAFs as both prognostic indicators and mechanistic drivers of tumor progression, immune suppression, and resistance to radiotherapy, immunotherapy, and metastatic control.