Epidermal Tumor Cell Signal Transduction Molecules In The Abnormal Expression And Regulation Of Retinoic Acid To Its

Objective First, the aim of this study was to explore the role of the expression of some important signal transduction molecules in the development of human epidermal non-melanoma tumors. Then with the establishment of an experimental model in vitro in which inhibition of the growth of epidermoid carcinoma cells was tested with retinoids of three generations, respectively, and retinoids induced-apoptosis was investigated. The relationships among retinoids-induced growth inhibition, apoptotic cell death and regulation of some important molecules in signaling transduction in epidermoid carcinoma cells were also analyzed. These researches would provide a scientific evidence for clinically choosing adequate retinoids therapy in suitable patients with epidermal tumors .Methods The paraffin-embedded samples were retrieved from files of department of pathology in the Second Affiliated Hospital of Zhejiang University, including 30 cases of skin squamous cell carcinomas(SCC), 20 cases of basal cell carcinomas(BCC), 20 cases of seborrhoeic keratosis(SK) and 20 cases of normal skin(from head,face,trunk,extremities and the like). Signal tranducer and activator of transcription 3 (STAT3) andmitogen-activated protein kinases (MAPK) are two important signal cascade molecules, the expression of their activation types phosphorylated STAT3 (P-STAT3), phosphorylated MAPK(p-MAPK) , expression of the down stream gene CyclinD1 , E-cadherin and p53 protein in human epidermal tumors were investigated by EnVision immunohistochemical staining technique. After treatment with three different generation retinoids including all-trans retinoic acid, acitretin and arotinoid , inhibition of cellular growth of A431 cells and HaCat cells was determined by MTT method. Morphological changes of apoptosis induced by retinoids were evaluated by light microscopy and electron microscopy, and further were corroborated with flow cytometry through measuring DNA content and Annexin-V binding staining. The mRNA expression of STAT3, CyclinDI and p42/p44MAPK induced by retinoid in A431 cells were investigated by reverse transcriptase polymerase chain reaction(RT-PCR). The expression level of p-STAT3 and CyclinD protein was detected by Western blot.Results ① The positive rate of p-STAT3 protein expression was abnormally increased in SCC and BCC as compared to normal skin and SK (p < 0.01). Expression of p-STAT3 protein in SCC was also significantly higher than that in BCC (p < 0.05). However there were no significant difference of p-MAPK protein expression among the normal skin .benign and malignant epidermal tumors. The positive rate of p-STAT3 expression was correlated with both the tumor differentiation degree and the depth of tumor invasion in SCC(p<0.05), whereas there was no correlation between the positive rate and the tumor size. ② There existed positive correlation between the positive rate of P-STAT3 expression and cyclinD1,as well as between the p-STAT3 expression and p53 in SCC, both p< 0.05, rs being 0.624 and 0.641 .respectively. However a negative correlation between the positive rate of p-STAT3 expression and the expression of tumor metastasis suppressorgene E-cadherin was found in SCC (rs= - 0.372, p< 0.05).③ The inhibitary rate of acitretin on A431 cells growth was higher than that of all-trans retinoic acid in the same cultured concentration and time. However, the third generation retinoid arotinoid could not inhibit the growth of A431 cells. The Acitretin could significantly inhibit the growth of A431 cells in vitro in a dose dependent manner ,with the following four concentrations, 5 × 10-5 mol/L 10-5 mol/L 5×10-6 mol/L and 10-6 mol/L. And there existed a time dependent manner in the effect of inhibition proliferation on A431 cells by acitretin. The inhibitary rate was higher in A431 cells than that in HaCat cells treated with the same concentratin of acitretin for the same times. ④ By light and electron microscopy, morphological changes revealed characteristics of cell apoptosis including condensed blebbed chromatin and apoptotic bodies.