An investigation of the role of the ErbB receptor family in chemotherapeutic drug resistance and invasion in human breast cancer
Glynn, Sharon (2002) An investigation of the role of the ErbB receptor family in chemotherapeutic drug resistance and invasion in human breast cancer. PhD thesis, Dublin City University.
Full text available as:
The purpose of the work described in this thesis was to investigate the effects of upregulation of c-erbB-2 by cDNA transfection and the downregulation by ribozyme transfection on chemotherapeutic drug sensitivity, in vitro invasion, and expression of a range of mRNA and proteins.
Four novel multidrug resistant variants of the human breast carcinoma cell line, MDAMB- 435S-F, were established by pulse selection with taxol or adriamycin. In vitro toxicity tests revealed that the taxol resistant variants, MDA-MB-435S-F/Taxol-10p and MDA-MB-435S-F/Taxol-10p4p were significantly more resistant to taxol, with crossresistance to vincristine and taxotere, but not to adriamycin, carboplatin, etoposide or 5-fluorouracil. Adriamycin accumulation studies revealed that both variants displayed increased adriamycin efflux. P-glycoprotein and possibly topoisomerases, but not mrpl, mrp2, mrp4, mrp5, DHFR, thymidylate synthase or GST n, were found to play a role in taxol resistance.
MDA-MB-435S-F cells were resistant to adriamycin selection. MDA-MB-435S-F/AdrlOp gained no significant increase in resistance to adriamycin following 10 rounds of exposure to adriamycin, although it did become resistant to VP-16 and was sensitised to vincristine and 5-fluorouracil. MDA-MB-435S-F/Adr-10pl0p was slightly resistant to adriamycin, VP-16, taxotere and vincristine. It was sensitised to taxol, 5-fluorouracil and carboplatin. P-glycoprotein, mrpl, mrp2, mrp4 and mrp5 were not altered at the mRNA level in the adriamycin selected variants. Reduced adriamycin accumulation appears to be the mechanism by which MDA-MB-435S-F/Adr-10pl0p became slightly resistant to adriamycin.
Drug selection induced c-erbB-1 expression at protein but not mRNA level in MDAMB-435S-F. C-erbB-3 protein levels fell dramatically after drug selection. Drug selection of MDA-MB-435S-F induced more aggressively invasive cell lines, as defined by the gain of an ability to invade and relocate. This is a novel discovery for this thesis. The aggressive two-staged invasive phenotype appears to be linked to decreased adhesion and motility and perhaps c-erbB-1 induction and c-erbB-3 repression, but not to increased secretion of a range of proteases. C-erbB-2 was not found to play a role.
Archive Staff Only: edit this record