Cell cycle regulation and proliferation in lichen sclerosus

Genital lichen sclerosus (LS) is considered a potential precursor lesion of squamous cell carcinoma. We aimed to investigate the expression pattern of cell cycle regulators, tumour suppressor proteins and proliferation markers in genital LS as compared to extragenital LS (ELS) and healthy controls (HC).

In order to assess the expression of minichromosome maintenance protein 3 (MCM3), MCM7, Ki-67, cyclin D1, cyclin E, p16, p21, and p53, immunohistochemistry and immunofluorescence were performed on skin specimens obtained from the genital region of LS patients (short-standing LS, n=19; long-standing LS, n=15), patients with ELS (n=10), and HC (n=8).

Median protein expression of MCM3 and Ki-67 was significantly higher in LS when compared to ELS and HC. In patients with long-standing LS, the expression profiles of MCM3 and Ki-67 significantly correlated. Moreover, long-standing LS lesions showed significantly increased expression of p53 when compared to short-standing LS, ELS, and HS. Immunoreactivity of MCM7, p16, p21, cyclin D1 and cyclin E did not significantly differ between the groups.

Tumour suppressor proteins such as p53 are significantly overexpressed in genital LS when compared to extragenital disease and healthy skin. The significant p53 overexpression, particularly in long-standing genital lesions, may reflect the increased risk of malignant transformation and/or oxidative stress associated with LS. Moreover, we have demonstrated that proliferation markers such as Ki-67 and MCM3 are significantly up-regulated in genital LS as compared to controls. With regard to cell cycle regulation and proliferation rates, ELS significantly differs from its genital counterpart.