TY - JOUR
T1 - An etoposide-resistant lung cancer subline overexpresses the multidrug resistance-associated protein
AU - Doyle, L. A.
AU - Ross, D. D.
AU - Ordonez, J. V.
AU - Yang, W.
AU - Gao, Y.
AU - Tong, Y.
AU - Belani, C. P.
AU - Gutheil, J. C.
N1 - Funding Information:
We would like to thank Drs SPC Cole and CE Grant for helpful suggestions and the gift of MRP cDNA. and Dr LF Liu for the gift of topoisomerase II antisera. We are indebted to Drs A Hindenberg. AF Gazdar and M Center for gifts of cell lines, and to Drs Center and N Krishnamachary for the gift of MRP antisera. We would also like to thank Ms F Wade and Ms H Spiker for help in preparing the manuscript. This study was supported by the Bristol-Myers-Squibb Corporation under a research grant programme for studies of tumour resistance to chemotherapy.
PY - 1995/9
Y1 - 1995/9
N2 - We have characterised an etoposide-resistant subline of the small-cell lung cancer cell line, UMCC-1, derived at our centre. Subline UMCC-1/VP was developed by culturing the parent line in increasing concentrations of etoposide over 16 months. UMCC-1/VP is 20-fold resistant to etoposide by MTT assays, relative to the parent line, and is cross-resistant to doxorubicin, vincristine and actinomycin D, but not to taxol, cisplatin, melphalan, thiotepa or idarubicin. Topoisomerase II immunoblotting demonstrates a 50% reduction of the protein in the resistant subline. The UMCC-1/VP subline demonstrates a marked decrease in the accumulation of [3H]etoposide relative to the parent line, as well as a modest reduction in the accumulation of daunorubicin. Reverse transcription-polymerase chain reaction assays demonstrate no detectable mdr1 expression but marked expression of the multidrug resistance-associated protein (MRP) gene in the resistant subline. Northern blotting with an MRP cDNA probe confirms marked overexpression of the MRP gene only in the UMCC-1/VP subline. Western blotting with antisera against MRP peptide confirms a 195 kDa protein band in the UMCC-1/VP subline. Southern blotting experiments demonstrate a 10-fold amplification of the MRP gene in the resistant subline. Depletion of glutathione with buthionine sulphoximine sensitised UMCC-1/VP cells to daunorubicin and etoposide. Our studies indicate that MRP gene expression may be induced by etoposide and may lead to reduced accumulation of the drug.
AB - We have characterised an etoposide-resistant subline of the small-cell lung cancer cell line, UMCC-1, derived at our centre. Subline UMCC-1/VP was developed by culturing the parent line in increasing concentrations of etoposide over 16 months. UMCC-1/VP is 20-fold resistant to etoposide by MTT assays, relative to the parent line, and is cross-resistant to doxorubicin, vincristine and actinomycin D, but not to taxol, cisplatin, melphalan, thiotepa or idarubicin. Topoisomerase II immunoblotting demonstrates a 50% reduction of the protein in the resistant subline. The UMCC-1/VP subline demonstrates a marked decrease in the accumulation of [3H]etoposide relative to the parent line, as well as a modest reduction in the accumulation of daunorubicin. Reverse transcription-polymerase chain reaction assays demonstrate no detectable mdr1 expression but marked expression of the multidrug resistance-associated protein (MRP) gene in the resistant subline. Northern blotting with an MRP cDNA probe confirms marked overexpression of the MRP gene only in the UMCC-1/VP subline. Western blotting with antisera against MRP peptide confirms a 195 kDa protein band in the UMCC-1/VP subline. Southern blotting experiments demonstrate a 10-fold amplification of the MRP gene in the resistant subline. Depletion of glutathione with buthionine sulphoximine sensitised UMCC-1/VP cells to daunorubicin and etoposide. Our studies indicate that MRP gene expression may be induced by etoposide and may lead to reduced accumulation of the drug.
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U2 - 10.1038/bjc.1995.370
DO - 10.1038/bjc.1995.370
M3 - Article
C2 - 7669558
AN - SCOPUS:0029098798
SN - 0007-0920
VL - 72
SP - 535
EP - 542
JO - British Journal of Cancer
JF - British Journal of Cancer
IS - 3
ER -