ISSN:
1434-0879
Keywords:
Prostate cancer
;
Dunning tumor Androgen-independent
;
Multidrug resistancemdr1b gene
Source:
Springer Online Journal Archives 1860-2000
Topics:
Medicine
Notes:
Abstract Prostate carcinomas are in general resistant against virtually all cytotoxic drugs. Up to now it has not been thoroughly evaluated whether specific resistance factors, such as the expression of theMDR1 gene, play a role in this multi-agent resistance and whether there is a link between drug resistance and hormone-independent growth. We investigated the resistance patterns of a hormone-sensitive and four hormone-independent Dunning rat carcinoma sublines against four drugs which are substrates of P-glycoprotein (vinblastine, taxol, doxorubicin, and etoposide) and two agents (methotrexate and cis-platinum) which are not transported by this efflux pump. All hormone-insensitive sublines, AT.1, AT. 3.1., MatLu and Mat LyLu, continuously showed a clearly enhanced resistance (3- to 26-fold) against the P-glycoprotein substrates, compared to the hormone-sensitive subline G. Only two of the androgen-independent sublines displayed enhanced resistance against methotrexate, whereas all of them were more sensitive against cisplatin than the androgen-sensitive G cells. By addition of verapamil the resistance against vinblastine (9- to 10-fold) and taxol (6.7- to 26.7-fold) in the hormone-insensitive cells could be almost totally reversed. Furthermore, the fluorescent P-glycoprotein substrate rhodamine-123 was effectively pumped out of the four tested hormone-independent cell lines, whereas the hormone-sensitive G cells were unable to extrude the dye. By reverse transcriptase polymerase chain reaction (RT-PCR) with primers specific for the ratmdr1b gene, the homologue to the humanMDR1 gene, we could easily detectmdr1b expression in the androgen independent cell lines, but not in the G cells. Our results suggest that the product of the ratmdr1b gene is involved in the multidrug resistance of androgen-independent Dunning prostate carcinoma cells.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF00941904
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