C-Jun expression in lichen planus, psoriasis, and cutaneous squamous cell carcinoma, an immunohistochemical study

The AP-1 transcription factor complex is a key player in regulating inflammatory processes, cell proliferation, differentiation, and cell transformation. The aim of the present study is to investigate C-Jun (one of AP-1complex) expression and its proliferative role in skin samples of lichen planus, psoriasis as common inflammatory skin diseases and squamous cell carcinoma using immunohistochemical method. The present study was carried out on skin biopsies of 15 psoriatic patients, 15 lichen planus patients, 15 SCC, and 15 normal skin biopsies. Nuclear expression of C-Jun was detected in basal and few suprabasal layers of epidermis of normal skin. C-Jun was expressed in the whole epidermal layers of both psoriasis (14/15) and lichen planus (15/15) in addition to its expression in lymphocytic infiltrate in the latter in about half of cases (8/15). C-Jun was also expressed in 93.3% (14/15) of SCC in a percentage lower than that of psoriasis, lichen planus, and normal skin. The percentage of C-Jun expression in SCC was significantly associated with an early stage (p = 0.000), free surgical margins (p = 0.022), and small tumour size (p = 0.003).

The marked reduction of C-Jun in SCC in comparison to normal skin and inflammatory skin dermatoses may refer to its tumour suppressor activity. C-Jun expression in SCC carries favourable prognosis. Absence of significant association between C-Jun and Ki-67 either in SCC or inflammatory skin diseases indicates that it does not affect proliferative capacity of cells.