Identification of the heterogeneous nuclear ribonucleoprotein A2/B1 as the antigen for the gastrointestinal cancer specific monoclonal antibody MG7.
MG7 is an early gastrointestinal cancer specific monoclonal antibody. It can detect gastric cancer with high sensitivity and specificity. However, the target antigen for MG7 has not been identified. Western blot analysis revealed that the MG7 antibody reproducibly recognized two approximately 35 kDa proteins in the total cell lysates of human gastric carcinoma cell lines KATO III and MKN-45. Using a proteomic approach, we identified these MG7 immunoreactive proteins as the human heterogeneous nuclear ribonucleoprotein A2/B1 (hnRNP A2/B1). Western blot analysis of nuclear and cytosolic fraction of KATO III cells using either MG7 or hnRNP A2/B1 antibodies confirmed that the target antigen is located exclusively in the nucleus. With the use of archival samples, we also found that the level of hnRNP A2/B1 protein was increased in gastric cancer tissues (4 out of 5 patients), when compared to their corresponding matching normal stomach tissue.
Lee
Chi-ho
CH
The Proteomic Task Force, Department of Applied Biology and Chemical Technology, The Hong Kong Polytechnic University, Hong Kong, China.
Lum
John Hon-kei
JH
Cheung
Belinda Pik-yuen
BP
Wong
Man-sau
MS
Butt
Yoki Kwok-chu
YK
Tam
Ming F
MF
Chan
Wing Y
WY
Chow
Chit
C
Hui
Pak-kwan
PK
Kwok
Francis S L
FS
Lo
Samuel Chun-lap
SC
Fan
D M
DM
D000328:Adult; D000911:Antibodies, Monoclonal / Q000737:chemistry* / Q000378:metabolism; D000912:Antibodies, Neoplasm / Q000737:chemistry*; D000951:Antigens, Neoplasm / Q000737:chemistry*; D015153:Blotting, Western; D045744:Cell Line, Tumor; D002467:Cell Nucleus / Q000378:metabolism; D003600:Cytosol / Q000378:metabolism; D030562:Databases, Protein; D004591:Electrophoresis, Polyacrylamide Gel; D005260:Female; D005753:Gastric Mucosa / Q000378:metabolism; D005770:Gastrointestinal Neoplasms / Q000276:immunology / Q000378:metabolism*; D015972:Gene Expression Regulation, Neoplastic; D034481:Heterogeneous-Nuclear Ribonucleoprotein Group A-B / Q000096:biosynthesis* / Q000737:chemistry*; D006801:Humans; D008297:Male; D008875:Middle Aged; D010455:Peptides / Q000737:chemistry; D016133:Polymerase Chain Reaction; D040901:Proteomics / Q000379:methods*; D012984:Software; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization; D015854:Up-Regulation
D000911:Antibodies, Monoclonal; D000912:Antibodies, Neoplasm; D000951:Antigens, Neoplasm; D034481:Heterogeneous-Nuclear Ribonucleoprotein Group A-B; C503210:MG7 monoclonal antibody; D010455:Peptides