The role of PRP4 kinase in breast cancer chemotherapy resistance

Even with early diagnosis and treatment, 15-20% of breast cancer patients will develop recurrent or metastatic disease. For these patients chemotherapy resistance is a major hurdle in curing their disease. In this proposal we will investigate the role of a protein called the pre-mRNA splicing factor 4 kinase (PRP4K) in chemotherapy resistance to the microtubule poison paclitaxel, one of the front line drugs used to battle breast cancer. Paclitaxel kills cancer cells by binding microtubules, the wires that help cells pull-apart and divide, and PRP4K has been recently shown to control how the cell responds to microtubule poisons. Using breast cancer cells grown in the lab, and human breast tumours implanted in zebrafish this research project aims to determine how changes in PRP4K protein levels affect the paclitaxel sensitivity of breast cancer cells. This study will also identify the protein targets of PRP4K using state-of-the-art protein microchips, which may uncover new cellular pathways to target drug-resistant tumours. The knowledge gained by these studies will be important in devising new therapies that target chemotherapy-resistant breast cancer, with the ultimate goal of improving the survival of breast cancer patients. AIM 1: To determine the impact of altered PRP4K protein levels on taxane resistance in breast cancer cells a) in vitro and b) in vivo using the zebrafish animal tumour model.In this aim we will determine if manipulation of PRP4K protein levels can alter the taxane sensitivity of breast cancer cells in vitro or in vivo using a novel zebrafish tumour animal model we have developed. Changes in PRP4K protein levels will then be correlated with changes in mitotic checkpoint activity in response to taxanes.AIM 2: To identify the protein substrates of PRP4K and potentially new signaling pathways involved in taxane resistance.To aid our understand of the function of PRP4K in the breast cancer taxane resistance, we will determine substrates of PRP4K, which will provide new insight into the signaling pathways that regulate chemotherapy resistance and provide new targets to deal with resistance. Both directed kinase assays against known mitotic checkpoint proteins and an unbiased high-throughput protein-chip kinase assays will be performed.