Thesis--Ph. D., University of Hong Kong, 1978. / Typescript.

published_or_final_version / Paediatrics and Adolescent Medicine / Doctoral / Doctor of Philosophy

published_or_final_version / Medical Sciences / Master / Master of Medical Sciences

published_or_final_version / abstract / toc / Botany / Master / Master of Philosophy

published_or_final_version / Zoology / Master / Master of Philosophy

published_or_final_version / Microbiology / Doctoral / Doctor of Philosophy

No description available.

No description available.

No description available.

Over-expression of either P-gp1 and/or MRP1 in tumor cell lines confers resistance to structurally diverse anti-cancer drugs. Although the role of these two proteins in clinical drug resistance remains to be confirmed, the use of Pgp1-specific inhibitors in combination with standard anti-cancer drugs have demonstrated significant improvement in clinical response. However, evidence exists that reversal of P-gp1 alone is not sufficient. Therefore, while no drugs are currently available that can efficiently reverse MRP1 drug efflux in tumor cells, there is an urgent need to develop MRP1-specific blockers. In an effort to gain a better understanding of MRP1-drug interactions and to identify sequences within MRP1 that interact directly with drugs, we developed two structurally diverse photosensitive drug analogues, a quinoline-based compound (IACI) and a xanthone-derivative (IAARh123). Both compounds photolabeled MRP1 and showed a direct and specific interaction with the protein at physiologically relevant sites. Initial mapping of photolabeled sequences in MRP1 (Chapters 2 and 3), identified multiple IACI- or IAARh123-photolabeled peptides (∼4--7 kDa) derived from both the N-terminal (MSD0+MSD1+NBD 1) and C-terminal (MSD2+NBD2) domains of MRP1. A subsequent study (Chapter 4), using MRP1 variants with hemagglutinin (HA) epitopes inserted at eight different locations, led to a higher resolution mapping of the previously identified IACI- or IAARh123-labeled peptides. Specifically, two photolabeled peptides (∼6--7 kDa), derived from variants with insertions at positions 574 and 1222, were immunoprecipitated with anti-HA monoclonal antibody. Based on the location of the HA epitopes in the latter variants together with molecular masses of the two peptides, the photolabeled amino acid residues were localized to MRP1 sequences encoding transmembranes 10 and 11 of MSD1 and transmembranes 16 and 17 of MSD 2. Interestingly, the same sequences were photolabeled with both