FBP1 Is Highly Expressed In Human Hypertrophic Scars And Increases Fibroblast Proliferation And Apoptosis

BackgroundHypertrophic scar is a common complication of skin wound healing,often occurs after human skin wound repair,especially in large areas of burn wounds.The proliferation of fibroblasts and the extracellular matrix,especially the abnormal deposition of collagen,play important roles in the development of hypertrophic scars.Hypertrophic scars affect not only the appearance of the skin but also its performance,as such scars lead to a lack of sweat production,as well as itching,paresthesias and other forms of discomfort.Furthermore,severe scars can cause joint spasms and limb deformities and can affect patient physical and mental health,as well as patient social functioning.Therefore,how to inhibit the growth of scar and reduce the formation of scar has been the focus of clinical treatment.Unfortunately,effective treatments for hypertrophic scars are still lacking.Clinical works intended to develop treatments for hypertrophic scars are urgently needed to solve this problem.In recent years,with the increasing number of studies regarding the mechanism of hypertrophic scar formation and the establishment of animal models and tissue engineering,we have a deeper understanding of its mechanism and treatment.The occurrence of hypertrophic scars may be related to the overexpression of proto-oncogenes(like Bcl-2,Smad,c-myc)that promote the proliferation of fibroblast and the mutation of tumor suppressor genes(like p53,Fas,RUNX3,p27,Rb exon 27 and P16)that induce the apoptosis of fibroblast.The proto-oncogene c-myc is associated with the development and progression of many types of tumors and regulates cell proliferation and differentiation.C-myc is highly expressed in proliferating cells and has low expression in resting or differentiated cells.FBP belongs to an ancient single-stranded DNA-binding protein family.Its activity requires the appropriate regulation of c-myc.Once c-myc is abolished,distal upstream regulatory elements are no longer supported.In contrast,the reduction in monotonicity of distal upstream regulatory elements in anti-FBP RNA is associated with the down-regulation of endogenous c-myc gene expression.It was also confirmed that an appropriate level of FBP expression is necessary to maintain c-myc because c-myc cannot be transcribed if there is no FBP.In histology,hypertrophic scars are manifested in the proliferation of fibroblasts and the abnormal deposition of extracellular matrix,especially collagen,to a certain extent similar to tumor development.Studies have shown that proto-oncogene c-myc promotes fibroblast proliferation in hypertrophic scars,and FBP1 is involved in the regulation of c-myc expression in fibroblasts.Studies on FBP1 have focused mainly on its expression in tumors,it was found to be highly expressed in tumor tissue.Fewer studies have focused on its expression in scars.In this study,we explored the difference in FBP1 expression between normal skin and hypertrophic scars and evaluated the effects of FBP 1 on fibroblasts to provide clinicians with more information that can be used in the treatment of hypertrophic scars.Material and methodsHuman normal skin and scar specimens were collected during clinical surgery.One portion of each tissue specimen was embedded in paraffin and sliced to observe differences in histological features and FBP1 expression by immunohistochemistry and western blotting.The other portion of each tissue specimen was cultured to obtain fibroblasts.Fibroblasts from the 2nd to the 6th passage were used for the experiments,which were divided into the following two groups:an experimental group,whose cells were transfected with an siRNA targeting FBP1,and a control group,whose cells where not transfected.MTT and TUNEL assays were performed respectively to assess fibroblast proliferation and apoptosis,flow cytometry(PI single staining)was performed assess cell cycle,and western blotting was performed to assess protein expression.ResultsWe obtained fibroblasts by primary tissue culture and found that FBP1 was highly expressed in hypertrophic scars.MTT assay showed that an siRNA targeting FBP1 significantly reduced fibroblast proliferation in siRNA-treated cells compared to control cells.Flow cytometry assay showed the cell cycle was arrested in S phase,TUNEL assay showed that there was no difference in apoptosis between the two groups but western blotting showed that collagen I,collagen III,c-myc,caspase-3 and caspase-9 expression levels were all decreased in the experimental group.ConclusionFBP1 is highly expressed in human hypertrophic scars,increases c-myc expression,increases fibroblast proliferation,apoptosis and collagen expression.