Study On The Expression And Mutation Of PTEN In Nasopharyngeal Carcinoma

AIM PTEN gene at chromosome 10q23.3 was recently identified as the first tumor suppressor that has dual-specificity phosphatase with lipid and protein phoshpatase activation. PTEN has been showed to play an important role in the regulation of cellular differentiation, proliferation, reproduction, apoptosis, adhesion, invasion, mobility and migration, as well as signaling conduction and other's biological actions. The tumorigenesis and progression of nasopharyngeal carcinoma was involved in the interaction of tumor suppression and carcinogenesis which the incident in Guangdong province was high familial and regional. In this experiment, we investigated the expression and mutation of PTEN in nasopharyngeal carcinoma tissue and two types of cell line at the protein and gene level and discussed the mechanism of PTEN as well as the relationship between PTEN and tumorigenesis of nasopharyngeal carcinoma. So this study will do help to reveal the function of PTEN in tumor suppression and carcinogenesis and provide new method for gene diagnosis and therapy.Methods By using the immunohistochemistry (SABC method) flow cytometry laser confocal scanning microscope Western blotting and PCR-SSCP to detect and analyze the expression and mutation of PTEN at the protein and gene level in nasopharyngeal carcinomas tissue and adjacent squamous epithelial cells of different histological types and pathological grade, as well as in two types of nasopharyngeal carcinomas squamous epithelial cell line. Results Positive staining for PTEN in nasopharyngeal carcinoma and normal nasopharyngeal epithelial cells was observed in both the cytoplasm and nucleus. The positive expression of PTEN in squamous cell carcinoma showed lower than that of in other types including undifferentiated no-keratinizing and differentiated no-keratinizing carcinoma. The positive rates of PTEN expression decreased from normal nasopharyngeal epithelium to low differentiated nasopharyngeal carcinoma with significant difference (P0.05). The expression of PTEN in carcinoma had correlation with clinical stage that PTEN expression in early clinical stage showed higher than that of in late stage(P<0.05). The result of cell lines was that the positive signals were also found in cytoplasm and nucleus. The date of the percent of positive expression mean fluorescent intensity of cell line in CNE1 cell line was at higher level than that of in CNE2 cell line (PO.05), but the rate of fluorescent intensity of cell line in CNE1 by LCSM and Western blotting was lower than that of in CNE2 cell line(P<0.05). And the rate of PTENmutation by PCR-SSCP was low in nasopharyngeal carcinoma, only 6.67%. And there was rarely mutated in cell lines.Conclusions The PTEN protein was localized in the cytoplasm and nucleus in normal nasopharyngeal epitheliunu nasopharyngeal carcinoma and two types of cell line. The expression and location of PTEN was related to differentiation degree of two types of cell line that the rate of PTEN expression decreased but the positive expression of PTEN in nucleus increased in malignant transformation of the nasopharyngeal squamous epithelial cell. The loss of PTEN in malignant transformation of the nasopharyngeal carcinoma was not uniform and mainly occurred in late clinical stage. The level of PTEN expression was related to differentiation degree histological types and clinical stage of nasopharyngeal carcinoma. It is presumed that PTEN gene deletion may be involved in carcinogenesis and progression of nasopharyngeal carcinoma in late stage. PTEN was rarely mutated in nasopharyngeal carcinoma and cell lines.