Protein And MRNA Expressions Of EphA2 And EphrinA1 In Squamous Cervical Carcinomas And Experimental Inhibition Of EphA2 In Vitro

The Eph receptor family is the largest subfamily of receptor protein tyrosine kinases (RTK). Signal conduction mediated by Eph receptors and their ligands Ephrins is involved in many processes of the life, including signal conduction of nervous system, angiogenesis and the regulation of cell-cell attachment. Recently, more and more investigators have focused on the roles of Eph family in tumours, it will be important to understand the potential mechanisms of signal conduction in carcinomas.Globally, cervical carcinoma is one of the most common gynaecological carcinomas. It is the second most frequent cause of cancer-related death in women, accounting 15% death cases in European countries. At present, mechanisms of carcinogenesis and methods toimprove prognosis and survival of patients with cervical carcinoma have been hotspots. Classical clinicalpathological factors such as age, stage of disease, volume, lymphatic spread and microvascular intensity have been confirmed to have a close relationship with prognosis. However, it is still mandatory to find better survival prognostic markers to better understand the biological behavior of cervical carcinoma, supply with better clinical management of cervical carcinoma.Compared with other members of Eph family, EphA2 has been shown frequently overexpressed in multiple types of carcinoma tissues and cell lines, such as, breast, protate, melanoma and esphageal carcinomas, et al. EphA2 is supposed to be involved in tumorigenesis and development of tumours, where it functions as a powerful oncoprotein. Experimentally it is sufficient to confer malignant transformation, invasiveness and metastasis on nontransformed mammary epithelial cells in vivo and in vitro when it is overexpressed. Interestingly, antisense-based targeting of EphA2 negatively regulates tumour cell growth in vitro, down-regulates expression of EphA2 and inhibits malignant cell behavior. EphrinAl(B16) is the major ligand for EphA2. However, little is known about its expression pattern in tumours. Miao et al have reported that activation of endogenous EphA2 kinase stimulated by EphrinAl ligand in PC-3 cells suppresses integrin-regulated cell adhesion, decreasing cell-cell attachment, endows tumour cells with more aggressive ability. Meanwhile, they found that cell adhesion mediated by integrin is mainly determined by density of EphrinAl ligand. All of these studies indicate that EphA2 and EphrinAl may be involved in the process of tumorigenesis and development of tumours, this will contribute to abetter understanding of cervical carcinogenesis. So far, no report concerned with the expressions of EphA2 and EphrinAl in cervical carcinoma in literature is available.Recent investigations have indicated that the relationships between overexpression of EphA2 and all sorts of clinicopathological features were different in different typies of turmour. For example, high levels of EphA2 protein in lung cancer predict a high risk of brain metastasis of patients, however, high levels of EphA2 protein did not relate to metastasis in prostaic carcinomas. In the present, many studies have focused on EphA2 expression in many tumours, most of them were involved in a relative small sample size, the results therefore might be influenced. For better understanding of cervical carcinogenesis and searching for alternatively effective therapy of cervical carcinoma, we systematically analysed the expression patterns of EphA2 and ephriAl in a series of Norwegian cervical carcinomas by immunohistochemistry and LCM (laser capture microdissection)-assisted RT-PCR, explored the relationship between protein expressions of EphA2 and EphrinAl and clinicopathological features and survival of cervical carcinoma patients. In addition, suppression the expression of EphA2 in Hela cells by using retrovirus-mediated RNAi method was also conducted, in order to study the possibility of gene therapy in vitro. This study is divided into two parts as listed below:First part: Protein and mRNA expressions of EphA2 and EphrinAl in squamous ce...