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3. MEDICAL AND HEALTH SCIENCES
Cervical cancer is the second most common cancer in women and is caused by a persistent infection of the cervical epithelium by the Human Papilloma Virus (HPV). Adherens (AJ) and tight junctions (TJ) play a key role in maintaining the apical-basolateral polarity and cohesive structure of epithelial cells. These junctions are maintained by the interaction of several key proteins including, claudins, catenins, cadherins and SNAIL. This study aims to identify the expression profile of several AJ and TJ proteins and to identify and genotype HPV DNA in several cases of cervical neoplasia. This study also aims to investigate the pathogenesis of aberrant AJ and TJ expression using cell based models. This study utilised a PCR based method to detect and genotype HPV DNA in 126 formalin-fixed paraffin embedded tissue samples. In tandem, tissue microarrays were produced from cervical biopsy samples and utilised to immunohistochemically examine the expression of several AJ and TJ proteins. The HeLa cervical cancer cell line was transfected with plasmids containing claudin-1 and claudin-7 genes to generate cell lines stably expressing claudin-1 claudin-7 respectively. Knockdown of SNAIL expression was performed in the SiHa cervical cancer cell line. An aberrant expression profile of AJ and TJ proteins was observed in cases of cervical neoplasia with increased expression of claudin-1, claudin-7, N-cadherin p120-catenin, SNAIL and decreased expression of E-cadherin compared to normal cervical epithelium. HPV DNA was detected and genotyped in 60 cervical tissue samples. HPV-16 was the most prevalent subtype, and was the subtype most associated with aberrant AJ and TJ expression. Knockdown of SNAIL expression had no effect on E-cadherin expression in SiHa cells while overexpression of claudin-1 and claudin-7 suppressed cellular motility in vitro, and decreased permeability in HeLa cells. This study identified aberrant expression of several AJ and TJ proteins which may be of potential use as biomarkers in the identification of pre-invasive cervical lesions. This study also identified that claudin-1 and claudin-7 overexpression in HeLa cells reduced cell migration and increased TEER values. This indicates the acquisition of invasive and metastatic properties in malignant cells is likely reliant on the synergistic interaction of several AJ and TJ proteins.
Cunniffe, C. The Role of Tight and Adherens Junctions in Cervical Neoplasia.. Doctoral Thesis. Technological University Dublin. doi:10.21427/D72P47