TY - JOUR
T1 - Intracellular P-glycoprotein expression is associated with the intrinsic multidrug resistance phenotype in human colon adenocarcinoma cells
AU - Meschini, Stefania
AU - Calcabrini, Annarica
AU - Monti, Elena
AU - Del Bufalo, Donatella
AU - Stringaro, Annarita
AU - Dolfini, Ersilia
AU - Arancia, Giuseppe
PY - 2000
Y1 - 2000
N2 - The 2 clones, LoVo 5 and LoVo 7, derived from untreated LoVo WT human colon adenocarcinoma cells and exhibiting different sensitivity to doxorubicin (DOX), were compared in order to identify possible determinants of intrinsic drug resistance. A multidrug resistant variant cell line, selected from LoVo WT cells by continuous exposure to DOX (LoVo DX), was also included in the study. Analysis of the expression and organization of cytoskeletal elements by flow cytometry and fluorescence microscopy evidenced a positive correlation between vimentin expression and DOX resistance in LoVo 7 and LoVo DX cells, whereas differences in actin, tubulin or cytokeratin did not seem to relate to drug response. The expression and localization of different drug transporters commonly implicated in drug resistance, i.e., the MDRI gene product P-glycoprotein (P-gp), the multidrug resistance-related protein MRP and the lung resistance-related protein LRP were also investigated by means of flow cytometry and fluorescence microscopy, following labeling with specific monoclonal antibodies. Surface expression of P-gp was only detected in LoVo DX cells, which also exhibited increased MRP and LRP protein levels. However, significant amounts of P-gp were found at intracellular sites in the intrinsically resistant LoVo 7 clone. Modulation of P-gp function by cyclosporin A was found to alter DOX accumulation and efflux in LoVo 7 cells, indicating that intracellular P-gp plays a functional role in drug trafficking and suggesting possible implications in determining the intrinsic resistance displayecl by this clone. (C) 2000 Wiley-Liss, Inc.
AB - The 2 clones, LoVo 5 and LoVo 7, derived from untreated LoVo WT human colon adenocarcinoma cells and exhibiting different sensitivity to doxorubicin (DOX), were compared in order to identify possible determinants of intrinsic drug resistance. A multidrug resistant variant cell line, selected from LoVo WT cells by continuous exposure to DOX (LoVo DX), was also included in the study. Analysis of the expression and organization of cytoskeletal elements by flow cytometry and fluorescence microscopy evidenced a positive correlation between vimentin expression and DOX resistance in LoVo 7 and LoVo DX cells, whereas differences in actin, tubulin or cytokeratin did not seem to relate to drug response. The expression and localization of different drug transporters commonly implicated in drug resistance, i.e., the MDRI gene product P-glycoprotein (P-gp), the multidrug resistance-related protein MRP and the lung resistance-related protein LRP were also investigated by means of flow cytometry and fluorescence microscopy, following labeling with specific monoclonal antibodies. Surface expression of P-gp was only detected in LoVo DX cells, which also exhibited increased MRP and LRP protein levels. However, significant amounts of P-gp were found at intracellular sites in the intrinsically resistant LoVo 7 clone. Modulation of P-gp function by cyclosporin A was found to alter DOX accumulation and efflux in LoVo 7 cells, indicating that intracellular P-gp plays a functional role in drug trafficking and suggesting possible implications in determining the intrinsic resistance displayecl by this clone. (C) 2000 Wiley-Liss, Inc.
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U2 - 10.1002/1097-0215(20000901)87:5<615::AID-IJC1>3.0.CO;2-4
DO - 10.1002/1097-0215(20000901)87:5<615::AID-IJC1>3.0.CO;2-4
M3 - Article
C2 - 10925353
AN - SCOPUS:0033868625
VL - 87
SP - 615
EP - 628
JO - International Journal of Cancer
JF - International Journal of Cancer
SN - 0020-7136
IS - 5
ER -