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Updated: Jun 25, 2026
Experimental Generation of Carcinoma-Associated Fibroblasts (CAFs) from Human Mammary Fibroblasts
Published on: October 25, 2011
Caveolin-1-/- null mammary stromal fibroblasts share characteristics with human breast cancer-associated fibroblasts
Federica Sotgia1, Francesco Del Galdo, Mathew C Casimiro
1Department of Cancer Biology, Kimmel Cancer Center, Thomas Jefferson University, 233 South 10 Street, Philadelphia, PA 19107, USA. federica.sotgia@jefferson.edu
Abstract:
Recently, we reported that human breast cancer-associated fibroblasts show functional inactivation of the retinoblastoma (RB) tumor suppressor and down-regulation of caveolin-1 (Cav-1) protein expression. However, it remains unknown whether loss of Cav-1 is sufficient to confer functional RB inactivation in mammary fibroblasts. To establish a direct cause-and-effect relationship, mammary stromal fibroblasts (MSFs) were prepared from Cav-1(-/-) null mice and subjected to phenotypic analysis. Here, we provide evidence that Cav-1(-/-) MSFs share many characteristics with human cancer-associated fibroblasts. The Cav-1(-/-) MSF transcriptome significantly overlaps with human cancer-associated fibroblasts; both show a nearly identical profile of RB/E2F-regulated genes that are up-regulated, which is consistent with RB inactivation. This Cav-1(-/-) MSF gene signature is predictive of poor clinical outcome in breast cancer patients treated with tamoxifen. Consistent with these findings, Cav-1(-/-) MSFs show RB hyperphosphorylation and the up-regulation of estrogen receptor co-activator genes. We also evaluated the paracrine effects of "conditioned media" prepared from Cav-1(-/-) MSFs on wild-type mammary epithelia. Our results indicate that Cav-1(-/-) MSF "conditioned media" is sufficient to induce an epithelial-mesenchymal transition, indicative of an invasive phenotype. Proteomic analysis of this "conditioned media" reveals increased levels of proliferative/angiogenic growth factors. Consistent with these findings, Cav-1(-/-) MSFs are able to undergo endothelial-like transdifferentiation. Thus, these results have important implications for understanding the role of cancer-associated fibroblasts and RB inactivation in promoting tumor angiogenesis.
Insights
Loss of caveolin-1 (Cav-1) in mammary fibroblasts causes functional retinoblastoma (RB) inactivation, mimicking cancer-associated fibroblasts. This Cav-1 loss promotes an invasive phenotype and predicts poor breast cancer outcomes.
Area of Science:
- Cancer Biology
- Cell Biology
- Tumor Microenvironment
Background:
- Human breast cancer-associated fibroblasts exhibit retinoblastoma (RB) tumor suppressor inactivation and reduced caveolin-1 (Cav-1) expression.
- The direct causal link between Cav-1 loss and RB inactivation in mammary fibroblasts is not established.
Purpose of the Study:
- To determine if Cav-1 deficiency is sufficient to cause functional RB inactivation in mammary fibroblasts.
- To investigate the phenotypic characteristics of Cav-1 null mammary stromal fibroblasts (MSFs) and their impact on mammary epithelia.
Main Methods:
- Phenotypic analysis of MSFs derived from Cav-1(-/-) mice.
- Transcriptome analysis comparing Cav-1(-/-) MSFs with human cancer-associated fibroblasts.
- Assessment of RB/E2F-regulated genes, RB hyperphosphorylation, and estrogen receptor co-activator gene expression.
- Evaluation of paracrine effects using conditioned media from Cav-1(-/-) MSFs on wild-type mammary epithelia.
- Proteomic analysis of conditioned media and assessment of MSF transdifferentiation.
Main Results:
- Cav-1(-/-) MSFs share transcriptional profiles with human cancer-associated fibroblasts, showing RB/E2F gene up-regulation consistent with RB inactivation.
- Cav-1(-/-) MSF gene signature predicts poor clinical outcomes in tamoxifen-treated breast cancer patients.
- Conditioned media from Cav-1(-/-) MSFs induces epithelial-mesenchymal transition in wild-type mammary epithelia, indicating invasiveness.
- Proteomic analysis revealed elevated proliferative/angiogenic factors in conditioned media, and Cav-1(-/-) MSFs exhibited endothelial-like transdifferentiation.
Conclusions:
- Loss of Cav-1 in mammary fibroblasts is sufficient to induce functional RB inactivation and confer a cancer-associated fibroblast phenotype.
- Cav-1 deficiency in the tumor microenvironment promotes an invasive epithelial phenotype and tumor angiogenesis.
- These findings highlight the critical role of Cav-1 in maintaining fibroblast function and suppressing tumor progression.
