Expressão da acido graxo sintase, ErbB-2, p27 E Skp2 na carinogenese bucal induzida por 1-oxido 4-nitroquinolina em camundongos e efeito antitumoral do Orlistat / Fatty Acid Sintase, ErbB-2, p27 E Skp2 expression in oral carcinogenesis induced by 4-nitroquinoline 1-oxide and antitumoral Orlistat effects

Eduardo Bauml Campagnoli

Squamous cell carcinoma of the oral cavity is one of the most common malignant epithelial neoplasms, and a better understanding of its molecular pathways could help the development of new treatment or preventive agents. Several proteins such as Fatty Acid Synthase (FAS), ErbB-2, p27 and Skp2 are involved in the tumorigenesis process. FAS has an enzyme with multiple functions, including the endogenous synthesis of saturated fatty acids. ErbB-2 is a transmembrane receptor that may have a role in cellular growth and differentiation. p27 is a cyclin-dependent kinase inhibitor and plays an important role on the negative regulation of the cell cycle. On the other hand, Skp2 is an ubiquitin ligase that targets p27 for ubiquitination and degradation. Studies have demonstrated that FAS inhibition induces apoptosis in various neoplastic cells and can suppress tumor cell proliferation. It has been demonstrated that Orlistat has anti-proliferative and anti-tumor properties through blocked FAS activity. Therefore, the aim of the present study was to investigate FAS, ErbB-2, p27 and Skp2 expression in the epithelium with chemically-induced dysplasia and squamous cell carcinoma, and to verify the effect of Orlistat on the carcinogenic process. Lesions were induced by 4NQO in the drinking water to C57BL/6 mice during 16 weeks. The animals were sacrificed after 16, 18, 20 and 25 weeks of treatment. One group also received intraperitonial injection of Orlistat, 240 mg/kg/day, during fifteen days. The tongues were removed and paraffin embedded tissues were cut and stained with hematoxylin and eosin. Dysplastic lesions and squamous cell carcinomas were analyzed in slides stained with hematoxylin and eosin. Immunohistochemistry assays were performed for Ki-67, FAS, ErbB-2, p27 and Skp2. The percentage of cells that reacted with the Ki-67 antibody was 26.57%, 22.85%, 26.12% and 23.86% in areas with mild, moderate, severe dysplasia and invasive carcinoma, respectively. The normal epithelium had low index of cellular proliferation, 4.31%. ErbB-2 showed increase in the expression in dysplastic and tumor areas, for both presented more 50% of positive cells. High expression of FAS was observed in areas with severe dysplasia and squamous cell carcinoma, although gradual increased was observed during all the carcinogenic process. Expression of p27 protein increased gradually during carcinogenesis and the biggest levels were detected in areas with severe dysplasia (57.50% of immunostaining cells) and invasive carcinoma (53.55% of positive cells). Skp2 immunoexpression was strictly cytoplasmic (Skp2-B), and it was increased in tumoral and dysplastic areas. Lesions of mice treated with Orlistat showed a 67.25% reduction when compared with non-treated animals. Moreover, cellular proliferation was reduced (2.58% of cellular immunostaining), and there were less cells immunostained for p27 and Skp2-B. Therefore dysplastic areas showed increased expression of Ki-67 and high expression of FAS, ErbB-2, p27 and Skp2-B, when compared with normal epithelium. ErbB-2 and Skp2-B had increased expression in the early stages of carcinogenesis. Moreover, Orlistat showed anti-tumoral and anti-proliferative effect in chemically-induced quamous cell carcinomas of the tongue

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