Role of insulin-like growth factor-1 in skin tags: a clinical, genetic and immunohistochemical study in a sample of Egyptian patients

Background: Skin tags (STs) are benign connective tissue neoplasms, in which insulin-like growth factor −1 (IGF-1) has a mitogenic and antiapoptotic activity. Purpose: We aimed to study for the first time, the possible role of IGF-1 (CA) 19 and rs6214 gene polymorphisms, and its tissue immunoreactivity in the pathogenesis of STs. Patients and methods: This case–control study included 40 ST patients and 20 controls. We searched for (CA) 19 single-nucleotide polymorphism (SNP) using conversional PCR and for rs6214 gene polymorphism using real-time PCR. IGF-1 tissue immunoreactivity was investigated using polyclonal IGF-1 antibody. Results: IGF-1 immunoreactivity showed significantly strong upregulation in epidermis (p=0.002) and dermal components (endothelial cells [p=0.038] and fibroblasts [p=0.004]) of excised STs than control skin. TT and CT rs6214 genotypes and its T allele were significantly associated with STs (p=0.006 and P=0.002, respectively). Also (<192 bp) and 192–194 bp (CA) 19 genotypes were significantly predominant in ST patients than controls (p=0.013). These 4 genotypes were significantly associated with development of multiple STs and epidermal IGF-1 tissue immunoreactivity in studied patients. Conclusions: IGF-1 (CA) 19 and rs6214 gene polymorphisms may contribute to a predisposition of STs in Egyptian patients, the role of which could be mediated through local upregulation of IGF-1 in cutaneous tissues.