Role of caveolin-1 in etoposide resistance development in A549 lung cancer cells.
Caveolin 1 expression is downregulated in various cancer cell lines. Interestingly, in several drug-resistant cancer cells, a strong induction of caveolin 1 expression has been reported suggesting a role for caveolin 1 in the acquisition and/or the maintenance of multidrug resistance phenotype. In addition, it was reported that p-glycoprotein localized to caveolin-rich membrane domains in these cells. In this study, we progressively exposed A549 lung adenocarcinoma cells to increasing doses of etoposide. Both R1 and R2 cell lines had greatly increased levels of p-glycoprotein expression while mrp expression levels were moderately increased but only R2 cells had raised caveolin levels compared to control A549 cells. Both caveolin-1 and p-glycoprotein colocalize in Triton-insoluble membrane domains in all our cell lines but only caveolins-1 was solubilized by the addition of octylglucoside at 4C suggesting that these two proteins are located in different membrane domains. Using an anti-caveolin-1 antibody, we did not succeed to immunoprecipitate p-glycoprotein. Interestingly, total cellular cholesterol (the major lipid component of caveolae and triton-insoluble domains) was greatly increased in both R1 and R2 cell lines compared to naive A549 cells.
Unité de Recherche en Pneumologie, Institut Universitaire de Cardiologie et de Pneumologie, l'Université Laval, Centre de Recherche Hôpital Laval, Sainte-Foy, Québec, Canada.
Martin M
MM
Bélanger
Martin
M
Gaudreau
Elise
E
Roussel
Jacques
J
Couet
D020168:ATP Binding Cassette Transporter, Subfamily B, Member 1 / Q000235:genetics / Q000378:metabolism; D000230:Adenocarcinoma / Q000188:drug therapy* / Q000378:metabolism / Q000473:pathology; D000972:Antineoplastic Agents, Phytogenic / Q000494:pharmacology* / Q000627:therapeutic use*; D051242:Caveolin 1; D022461:Caveolins / Q000502:physiology*; D002462:Cell Membrane / Q000378:metabolism; D002784:Cholesterol / Q000378:metabolism; D019008:Drug Resistance, Neoplasm; D005047:Etoposide / Q000627:therapeutic use*; D015972:Gene Expression Regulation, Neoplastic; D006801:Humans; D008175:Lung Neoplasms / Q000188:drug therapy* / Q000378:metabolism / Q000473:pathology; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction; D014407:Tumor Cells, Cultured
D020168:ATP Binding Cassette Transporter, Subfamily B, Member 1; D000972:Antineoplastic Agents, Phytogenic; C495540:CAV1 protein, human; D051242:Caveolin 1; D022461:Caveolins; D012333:RNA, Messenger; D005047:Etoposide; D002784:Cholesterol