Targeting cell adhesion as a method of sensitising metastatic tumour cells to TRAIL-induced apoptosis

Due to its selectivity in killing cancer cells, Tumour necrosis factor-related apoptosis-inducing ligand (TRAIL) has provided a potential new agent for cancer treatment. However, despite promising pre-clinical results, it appears that TRAIL therapies will be most effective when used in combination with a sensitizing agent. In light of previous evidence suggesting that cell adhesion could influence sensitivity to Tumour necrosis factor family ligands, this thesis presents a study of the effects of disrupting matrix adhesion on the sensitivity of human MDA-MB-231 breast and 1205Lu melanoma cell lines to TRAIL-induced apoptosis. This was investigated using a number of models including i) culturing cells on normal and low attachment plates; ii) disrupting the transcription of genes involved in cell attachment and spreading in MDA-MB-231 cells using shRNA to Myocardin-related transcription factors-A and B (MRTF-A/B); iii) disrupting the integrin signalling pathway using inhibitors or siRNA to β integrin subunits, talin, integrin-linked kinase (ILK), focal adhesion kinase (FAK) and SRC. With the exception of ILK depletion, disruption of cell adhesion and spreading in all models resulted in sensitisation to TRAIL-induced apoptosis. Cells under these conditions also showed alterations in death receptor signalling and amplification of intrinsic apoptosis pathway signalling through caspase-9. Both MRTF-A/B depleted cells and those treated with the SRC family kinase inhibitor PP2 showed alterations in signalling through ERK1/2. When investigated in an experimental model of metastasis in mice, FAK and SRC inhibitors increased the clearance of MDA-MB-231 cells from the mouse lung when used in combination with recombinant human TRAIL therapy. By utilizing these models, the work in this thesis has shown that disrupting cell adhesion could provide a new combination strategy to sensitise tumour cells to TRAIL therapy.EThOS - Electronic Theses Online ServiceGBUnited Kingdo