Lack of correlation between mdr-1 expression and volume-activation of cloride-currents in rat colon cancer cells.
Correlation between expression of the mdr-1 genes (a and b) at the mRNA and protein level and volume-activation of chloride-channels was studied in rat colon cancer CC531 cells by means of RT-PCR, Western blotting and patch clamp, respectively. Three different kinds of cell lines were used: CC531-PAR, CC531-COL and CC531-REV. At the mRNA level, the parental cell line CC531-PAR showed significantly less mdr-1a expression in comparison with CC531-COL, a drug-resistant cell line induced from the parental CC531 cells by growth in the presence of colchicin. The third cell line, CC531-REV, was a spontaneous revertant of the drug-resistant cell line to a drug-sensitive one, but with a maintained level of mdr-1a mRNA. In none of the three cell lines, mdr-1b mRNA could be detected. At the protein level, a clear difference in mdr1 expression between CC531-PAR/REV and CC531-COL was observed. Although the amount of mdr-1a mRNA detected in CC531-REV was comparable to that found in CC531-COL, the amount of mdr-1 encoded protein in CC531-REV was remarkably reduced. In all three cell types, cell swelling activated chloride-currents which could be blocked by NPPB.(ABSTRACT TRUNCATED AT 250 WORDS)
De Greef
C
C
Laboratorium voor Fysiologie, Leuven, België.
van der Heyden
S
S
Viana
F
F
Eggermont
J
J
De Bruijn
E A
EA
Raeymaekers
L
L
Droogmans
G
G
Nilius
B
B
D020168:ATP Binding Cassette Transporter, Subfamily B, Member 1 / Q000235:genetics* / Q000378:metabolism; D000230:Adenocarcinoma / Q000235:genetics / Q000503:physiopathology*; D000818:Animals; D001483:Base Sequence; D018118:Chloride Channels / Q000502:physiology*; D003110:Colonic Neoplasms / Q000235:genetics / Q000503:physiopathology*; D018432:Drug Resistance, Multiple / Q000235:genetics*; D015870:Gene Expression; D007700:Kinetics; D008969:Molecular Sequence Data; D016133:Polymerase Chain Reaction; D012333:RNA, Messenger / Q000378:metabolism; D051381:Rats; D014407:Tumor Cells, Cultured
D020168:ATP Binding Cassette Transporter, Subfamily B, Member 1; D018118:Chloride Channels; D012333:RNA, Messenger