Objective To detect the expression intensity and distribution of minichromosome mainte-nance 2 protein (MCM-2) in normal skin and lesions of malignant and non-malignant hyperplasia. Methods Three groups of samples were collected, I.e., malignant group (including 15 cases of Bowen disease or highly differentiated squamous cell carcinoma of Grade Ⅰ or Ⅱ ), non-malignant group (including 4 cases of chro-momycosis, 2 cases of sporotrichosis, 5 cases of seborrheic keratosis, 4 cases of verruca vuigaris, 4 cases of chronic eczema, 4 cases of cutaneous fibroma), and normal group (10 cases of normal human control). The distribution and intensity of MCM-2 expression in the epidermis of these samples were assessed by immuno-histochemical SP method. Results The expression of MCM-2 was observed in basal and superbasal layer of epidermis in lesions of malignant and non-malignant hyperplasia, and only in epidermal basal layer in normal skin. A significant increment was observed in the density of MCM-2 positive cells in superbasal layer in malignant lesion compared with the non-malignant lesion. The epidermal expression level of MCM-2 in the non-malignant lesion was significantly lower than that in the malignant lesion, but higher than that in the normal skin (μ = -2.529, -3.705, respectively, both P < 0.05); the same was true for the proportion of MCM-2-postive basal cells. Conclusions The expression of MCM-2 protein varies with the proliferation status of epidermal cells, and may serve as an objective marker for epidermal cell proliferation.

Objective To study the expressions of keratin 10, 14 and 17 (KI0, K14, K17) in psoriatic lesions before and after the treatment with acitretin. Methods Thirty patients with moderate or severe plaque psoriasis were included in this study. The cohort consisted of 19 males and 11 females with an average age of 33.9 years, and disease course of 4 months to 30 years. Patients were treated with acitretin for 8 weeks which started with an initial dose of 20 mg per day for 1 week, then switched to 0.5-0.75 mg per kilogramme of body weight per day until symptom improvement, finally maintained at a dose of 10-30 mg per day. The expression of K10, K14 and K17 was detected by immunohistochemical technique before and after treatment with acitretin. The relationship between the disease severity and levels of keratins was evaluated. Results Prior to the treatment, increased expression of K14 and K17 was observed in lesions of patients along with the decreased expression of K10 compared with the normal controls. After treatment, the expression of K14 and KI7 significantly decreased (both P < 0.01), while that of K10 increased (P < 0.01), and there was still a statistical difference between the patients and normal controls (P < 0.01). A significant decrease was observed in the PASI score of patients (P < 0.01). The changes in the expression levels of K10, K14 and KI7 before and after treatment were somewhat correlated with the clinical course and severity of psoriasis. Conclusions Systemic aeitretin can affect the expression of K10, K14 and K17 in psoriatic lesions, but the extent of changes in their expression is not always consistent with the improvement of clinical manifestations.