Abstract
Ovarian cancer is usually diagnosed in the advanced stages when the cancer has metastasised making it one of the most common gynaecological cancers with a high mortality rate. The development of drug resistance in such cancers is unfavourable. The aim of this study was to produce biomarkers of drug resistance in ovarian cancer, which can be used to identify a drug-resistant phenotype in patients allowing for alternative treatments besides the first-line choices of carboplatin and paclitaxel. Various methods were used in the study from western blotting to analyse protein expression, epithelial antigen staining to assess epithelial state of cell, scratch assays to determine drug-resistant phenotype, MTT assays to assess drug-inhibitor responses, Annexin V-FITC apoptosis detection assay for cell viability assessment, gene silencing assays to assess drug sensitivity on gene silencing and qPCR array led approach to identify genes upregulated in drug-resistant cell lines. Using an EMT-led approach, analysis of five common EMT markers led to the determination of SLUG as a probable biomarker with E-CADHERIN and β-CATENIN as possible biomarkers. Examination of the downstream signalling proteins of the MET receptor revealed RAC1 could be another possible biomarker. Using the qPCR-led approach, a list of upregulated genes in drug-resistant cell lines was produced with further protein analyses revealing ZEB1, STAT3 and WNT proteins as possible biomarkers. As EMT was used as a starting point to identify markers of drug resistance, to determine its association with drug resistance, a drug-resistant cell line model was produced through the induction of EMT. In conclusion, this study has produced a list of possible biomarkers of drug resistance in ovarian cancer fulfilling its aims. Further investigation of the biomarkers beyond the use of cell models could determine their reliability as biomarkers of drug resistance in ovarian cancer in the clinical setting.