Mutations in the tumour suppressor gene Adenomatous polyposis coli (APC) are found in 80 % of sporadic colorectal cancer (CRC) tumours and are also responsible for the inherited form of CRC, Familial adenomatous polyposis (FAP). In order to identify novel therapeutic targets for the treatment of APC mutated CRC, we have generated an in vitro model of APC mutant CRC using CRISPR-cas9 gene editing. Using the APC wildtype colorectal carcinoma cell line RKO, we targeted the cells with guide RNA (gRNA) targeting exon 2 or exon 15 (encodes 80 % of APC) of the APC gene. We generated isogenic cell lines which differed in the expression of APC, the controls were APC wildtype and the APC mutant (APC Lys736fs) cell lines expressed a truncated ~80 kDa APC protein. We used these cell lines to perform an siRNA screen against 720 kinases and kinase-related genes. We selected seven genes to investigate further, unfortunately none of the potential hits validated. Additionally, we performed an FDA-approved compound screen targeting over 1000 compounds. From this, we identified a group of HMG-CoA reductase (HMGCR) inhibitors known as statins, which selectively cause a greater loss in cell viability in the APC mutated cell lines, compared to the APC wildtype cells. Mechanistically, our data suggests this synthetic lethal relationship is due to a greater decrease in the anti-apoptotic protein survivin. We propose this is due to statins altering the localisation of Rac1, reducing Pak1 activation and reducing the level of Wnt signalling. This results in the reduction of the Wnt target gene survivin. We have successfully identified an FDA-approved family of compounds, which show synthetic lethality with the APC mutation in our in vitro model.
| Identifer | oai:union.ndltd.org:bl.uk/oai:ethos.bl.uk:766274 |
| Date | January 2018 |
| Creators | Shailes, Hannah |
| Publisher | Queen Mary, University of London |
| Source Sets | Ethos UK |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
| Source | http://qmro.qmul.ac.uk/xmlui/handle/123456789/43996 |
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