MGr1-Ag is associated with multidrug-resistant phenotype of gastric cancer cells.
BACKGROUND
MGr1-antigen (Ag) was previously reported as an upregulated protein in multidrug-resistant (MDR) gastric cancer cells. The aim of this study was to characterize the role of MGr1-Ag in the multidrug resistance of gastric cancer cells.


METHODS
Laser scanning confocal microscopy (LSCM), two-dimensional electrophoresis, and Western blot were used to detect MGr1-Ag in gastric cancer cells. The 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl-tetrazolium bromide (MTT) assay was used to determine the sensitivity of the MDR gastric cancer cells, SGC7901/VCR, to chemotherapeutic drugs. Adriamycin accumulation and retention in SGC7901/VCR cells were analyzed using flow cytometry.


RESULTS
LSCM showed that MGr1-Ag localized mainly on the membrane and partly in the cytoplasm of SGC7901/VCR cells. Western blot showed that the expression level of MGr1-Ag in SGC7901/VCR cells was higher than that in its parental cells, SGC7901, and that the apparent molecular weight and isoelectric point of MGr1-Ag were 42 kDa and pH 4.8, respectively. After incubation with MGr1 antibody, SGC7901/VCR cells showed significantly decreased IC(50) values for adriamycin (from 0.887 +/- 0.081 mg/l to 0.607 +/- 0.084 mg/l; P, 0.05), vincristine (from 0.707 +/- 0.055 mg/l to 0.557 +/- 0.042 mg/l; P, 0.05), and 5-fluorouracil (from 4.367 +/- 0.407 mg/l to 2.630 +/- 0.644 mg/l; P, 0.05), as well as slightly increased IC(50) values for mitomycin (from 0.183 +/- 0.045 mg/l to 0.198 +/- 0.048 mg/l; P. 0.05). In addition, incubation with MGr1 significantly enhanced adriamycin accumulation and retention in SGC7901/VCR cells.


CONCLUSIONS
Overexpression of MGr1-Ag is associated with the MDR phenotype of gastric cancer cells.
Shi
Yongquan
Y
Institute of Digestive Diseases, Xijing Hospital, Fourth Military Medical University, Xi'an 710032, Shaanxi Province, People's Republic of China.
Han
Ying
Y
Wang
Xin
X
Zhao
Yanqiu
Y
Ning
Xiaoxuan
X
Xiao
Bing
B
Fan
Daiming
D
D000911:Antibodies, Monoclonal / Q000378:metabolism / Q000627:therapeutic use*; D000941:Antigens / Q000276:immunology; D000951:Antigens, Neoplasm / Q000235:genetics* / Q000276:immunology; D000970:Antineoplastic Agents / Q000378:metabolism / Q000627:therapeutic use; D015153:Blotting, Western; D004317:Doxorubicin / Q000378:metabolism / Q000627:therapeutic use; D018432:Drug Resistance, Multiple / Q000235:genetics* / Q000276:immunology; D019008:Drug Resistance, Neoplasm / Q000235:genetics* / Q000276:immunology; D015180:Electrophoresis, Gel, Two-Dimensional; D004591:Electrophoresis, Polyacrylamide Gel; D005453:Fluorescence; D006801:Humans; D008826:Microbial Sensitivity Tests; D018613:Microscopy, Confocal; D010641:Phenotype; D013274:Stomach Neoplasms / Q000188:drug therapy* / Q000235:genetics* / Q000401:mortality; D015996:Survival Rate; D014407:Tumor Cells, Cultured
D000911:Antibodies, Monoclonal; D000941:Antigens; D000951:Antigens, Neoplasm; D000970:Antineoplastic Agents; C470229:MGr1-antigen, human; D004317:Doxorubicin