Human dermal fibrotic disease
keloid has been a clinical challenge because of its tumour-like growth and the lack of effective
therapy. Dysregulated alternative splicing events have been demonstrated in tumours and
fibrosis. In the current study, for the first time, it was demonstrated that the splicing regulator
polypyrimidine tract-binding protein (PTB), which plays a pivotal role in tumour proliferation, invasion and
metastasis, is overexpressed in
keloid tissues and fibroblasts. Additionally, TGF-β1 upregulated the expressions of PTB and its upstream regulator, C-MYC, in
keloid fibroblasts. Furthermore, we suppressed PTB using
siRNA in
keloid fibroblasts and in a
keloid xenograft nude mouse model. PTB knockdown significantly slowed the proliferation of
keloid fibroblasts and accelerated the regression of transplanted
keloid tissues, which was accompanied by a shift in the alternative splicing of USP5 and RTN4. Moreover, when PTB was suppressed, there was a reduction in excessive deposition of FN1 and COL3A1 in transplanted
keloid tissues. However, only FN1 was downregulated in
keloid fibroblasts that were cultured in media supplemented with TGF-β1. Our study provides evidence for the role of PTB in
keloid pathophysiology and offers a novel therapeutic target for
keloids. Most importantly, the role TGF-β1 regulation of PTB may provide new insights into the mechanisms underlying inflammatory
cytokine-induced
fibrosis.