Multidrug-resistance-associated protein MGr1-Ag is identical to the human 37-kDa laminin receptor precursor.
We report the isolation and functional characterization of the gene encoding MGr1-Ag, a multidrug-resistance-associated protein. A lambdagt11 cDNA library derived from colorectal carcinoma SW480 cells was screened with monoclonal antibody MGr1. DNA homology analysis of 22 positive clones (designated R1-R22) suggested human 37-kDa laminin receptor precursor (37LRP, R7/R9/R15/R16/R19/R20) and a novel gene (R22) as candidate genes encoding MGr1-Ag. Western blot analysis showed that anti-R20 serum reacted with a unique protein band that was consistent with MGr1-Ag, while anti-R22 serum could not react with MGr1-Ag. The coding gene for MGr1-Ag was amplified using reverse transcription-PCR. Sequence analysis revealed that the MGr1-Ag and 37LRP genes shared the same coding sequence. An in vitro drug sensitivity assay indicated that down-regulation of 37LRP by an antisense technique could significantly enhance the cytotoxicity of anticancer drugs to gastric cancer cells. Thus we draw the conclusion that MGr1-Ag is identical to 37LRP.
Shi
Y
Y
Institute of Digestive Diseases, Xijing Hospital, Fourth Military Medical University, Shaanxi Province, PR China.
Zhai
H
H
Wang
X
X
Wu
H
H
Ning
X
X
Han
Y
Y
Zhang
D
D
Xiao
B
B
Wu
K
K
Fan
D
D
D002277:Carcinoma; D015179:Colorectal Neoplasms; D015536:Down-Regulation / Q000502:physiology; D018432:Drug Resistance, Multiple / Q000502:physiology*; D006801:Humans; D008970:Molecular Weight; D027425:ATP-Binding Cassette, Sub-Family C Proteins / Q000235:genetics / Q000378:metabolism*; D011498:Protein Precursors / Q000235:genetics / Q000378:metabolism*; D017474:Receptors, Laminin / Q000235:genetics / Q000378:metabolism*; D013274:Stomach Neoplasms; D014407:Tumor Cells, Cultured
D027425:ATP-Binding Cassette, Sub-Family C Proteins; D011498:Protein Precursors; D017474:Receptors, Laminin