Identification of genes regulating invasive behaviour in a model of human cancer

• Main Author: Arshad, Azeem
• Published: Cardiff University 2010
• Subjects: 616.994
• Online Access: http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.584797

For this project I aimed to identify and investigate genes which regulate an invasive phenotype in thyroid carcinomas. I utilised an established <italic> in vitro</italic> model system which involves the introduction of the oncogenes RASV12, BRAF<super>V600E</super> and RET/PTC1 by retroviral infection into normal primary thyrocytes to represent the in vivo tumour situation. I adopted Affymetrix microarray gene expression profiling of the oncogene infected primary thyrocytes on U133 PLUS 2.0 arrays to identify candidate genetic markers facilitating thyroid invasion. In parallel I performed a literature analysis to identify additional markers of invasion. The genes identified from this analysis were Slug and Osteopontin. Osteopontin is over-expressed and enhances papillary carcinoma invasion in a Fisher rat cell line model of thyroid carcinoma. In tissue samples, Slug is over-expressed in papillary carcinomas. Currently, there is limited research on how Slug and Osteopontin regulate thyroid invasion. I have investigated the role of Slug and Osteopontin in tumour invasion through the employment of RNA interference. I have analysed the role of Slug and Osteopontin in a number of invasive mechanisms. The mechanisms analysed included degradation of the extracellular matrix, cell motility, regulation of the actin cytoskeleton during cell migration, cell-matrix interactions and cell-cell interactions. The results indicate that Osteopontin influences the actin cytoskeleton by regulating the formation of contractile stress fibres required for forward movement. Slug mediates tumour invasion by regulating the membrane bound matrix metalloproteinase MT1-MMP, and deregulating the cell-cell interactions which is important for maintaining normal epithelial architecture.