title: Overexpression of caveolin-1 induces alteration of multidrug resistance in Hs578T breast adenocarcinoma cells.
abstract: Caveolin-1 is a major caveolae-coat protein involved in a variety of cell signaling processes. Some studies have suggested that the level of caveolin-1 expression positively correlates with multi-drug resistance in cancer cells. We demonstrated for the first time that Hs578T doxorubicin resistant cells (Hs578T/Doxo), which contain low levels of endogenous caveolin-1 and high levels of P-glycoprotein, are rendered drug-sensitive by overexpression of exogenous caveolin-1. MTT assays showed that after overexpressing caveolin-1, the drug resistance of Hs578T/Doxo cells to doxorubicin and cisplatin was reduced from 25.4 +/- 1.5 and 65.3 +/- 2.5 microg/ml to 0.8 +/- 0.15 and 23.2 +/- 2.1 microg/ml, respectively (i.e. reduced by 97% and 64%, respectively). Furthermore, using rhodamine-123 efflux assays, we observed a significant decrease in P-glycoprotein activity in caveolin-1 overexpressing cells, similar to that observed with 5 microM cyclosporine A or 10 microM verapamil, 2 inhibitors of P-glycoprotein activity. Using confocal microscopy, subcellular fractionation and co-immunoprecipitation assays, a possible physical interaction between caveolin-1 and P-glycoprotein in the caveolae membrane was observed in Hs578T/Doxo cells overexpressing caveolin-1. These results suggest that overexpression of caveolin-1 changes the state of the cells from drug-resistant to drug-sensitive by inhibiting P-glycoprotein transport activity.
authors.affiliation: National Laboratory of Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing, China.
authors.forename: Chuanxi
authors.initials: C
authors.lastname: Cai
authors.forename: Jianwen
authors.initials: J
authors.lastname: Chen
mesh_terms: D020168:ATP Binding Cassette Transporter, Subfamily B, Member 1 / Q000378:metabolism*; D000230:Adenocarcinoma / Q000235:genetics* / Q000473:pathology; D000903:Antibiotics, Antineoplastic / Q000494:pharmacology; D001943:Breast Neoplasms / Q000235:genetics* / Q000473:pathology; D051242:Caveolin 1; D022461:Caveolins / Q000096:biosynthesis*; D004317:Doxorubicin / Q000494:pharmacology; D018432:Drug Resistance, Multiple / Q000235:genetics*; D005260:Female; D006801:Humans; D014407:Tumor Cells, Cultured; D015854:Up-Regulation
chemical_list: D020168:ATP Binding Cassette Transporter, Subfamily B, Member 1; D000903:Antibiotics, Antineoplastic; C495540:CAV1 protein, human; D051242:Caveolin 1; D022461:Caveolins; D004317:Doxorubicin