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Introduction: Recessive dystrophic epidermolysis bullosa (RDEB) is a rare skin blistering disorder due to a loss of function mutation in the collagen 7 (C7) gene. C7 activity loss upregulates thrombospondin-1 (TSP1), stimulating tissue growth factor-ß (TGF-ß), which promotes the development of cutaneous squamous cell carcinoma (cSCC) in RDEB patients. This C7-TSP1 interaction has not been described in normal fibroblasts; therefore, in this study, we tested the hypothesis that the level of intracellular C7 negatively correlates with TSP1 expression in normal fibroblasts.

Methods: In this basic research cell study, C7, TSP1, and pSMAD3 (phosphorylated SMAD3), a marker of TGF-ß activation, were extracted from normal breast fibroblasts, cultured in 10% fetal bovine serum (FBS), and quantified via Western blot. Data was normalized relative to GAPDH (glyceraldehyde 3-phosphate dehydrogenase) expression, a housekeeping gene. Pearson’s correlation coefficients were calculated.

Results: 5 fibroblast cultures were studied. Analysis of C7 vs. TSP1 expression demonstrated a large positive correlation (r = 0.62, 95% CI: [-1.89, 4.74]) that was not statistically significant (p = 0.26). Analysis of TSP1 vs. pSMAD3 expression demonstrated a small positive correlation (r = 0.11, 95% CI: [-0.59, 0.66]) that was not statistically significant (p = 0.89).

Discussion: A negative and positive correlation was expected between C7 and TSP1 and TSP1 and pSMAD3 expression respectively. Current results do not support the hypothesis, but more data is needed to form a conclusion. The general impact of this research would be to determine the presence of a novel role for C7-TSP1 activity in normal tissue.