Suppression of P-glycoprotein gene expression in Hs578T/Dox by the overexpression of caveolin-1.
Caveolin-1, the principal component of caveolae, is a 21-24 kDa integral membrane protein. The interaction of the caveolin-1 scaffolding domain with signaling molecules can functionally inhibit the activity of these signaling proteins. Little is known about how caveolin-1 influences the expression of P-glycoprotein (P-gp), an ABC transporter encoded by multi-drug resistance (MDR1) gene. To elucidate the possible mechanism between caveolin-1 and P-gp expression, in the present study, we overexpressed caveolin-1 in the Hs578T/Dox breast adenocarcinoma cells, a multidrug resistant line, and then selected single clone cells highly expressing caveolin-1 level. Both Western blot and confocal microscopy analyses showed that caveolin-1 was markedly overexpressed in the transfectants, while P-gp protein was almost abolished. Reverse transcription polymerase chain reaction also showed that the expression of P-gp mRNA was significantly suppressed in the transfectants. It was confirmed further by Northern blot analysis. Moreover, through measuring the changes of drug resistance and P-gp transport activity in the transfectants, we found that overexpression of caveolin-1 reversed drug resistance of transfectants and lowered their P-gp transport activity to the level of Hs578T/S. Taken together, our results indicate that such suppression of P-gp in the transfectants overexpressing caveolin-1 may occur at the transcriptional level.
Zhu
Hua
H
National Laboratory of Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Dantun Road 15, Chaoyang District, Beijing 100101, China.
Cai
Chuanxi
C
Chen
Jianwen
J
D020168:ATP Binding Cassette Transporter, Subfamily B, Member 1 / Q000235:genetics* / Q000378:metabolism; D000230:Adenocarcinoma; D001483:Base Sequence; D015152:Blotting, Northern; D001943:Breast Neoplasms; D051242:Caveolin 1; D022461:Caveolins / Q000235:genetics*; D045744:Cell Line, Tumor; D017931:DNA Primers; D018432:Drug Resistance, Multiple; D005260:Female; D015972:Gene Expression Regulation, Neoplastic / Q000235:genetics*; D006801:Humans; D012333:RNA, Messenger / Q000235:genetics; D020133:Reverse Transcriptase Polymerase Chain Reaction
D020168:ATP Binding Cassette Transporter, Subfamily B, Member 1; C495540:CAV1 protein, human; D051242:Caveolin 1; D022461:Caveolins; D017931:DNA Primers; D012333:RNA, Messenger