Identification of ATP synthase beta subunit (ATPB) on the cell surface as a non-small cell lung cancer (NSCLC) associated antigen.
BACKGROUND
Antibody-based immunotherapy has achieved some success for cancer. But the main problem is that only a few tumor-associated antigens or therapeutic targets have been known to us so far. It is essential to identify more immunogenic antigens (especially cellular membrane markers) for tumor diagnosis and therapy.


METHODS
The membrane proteins of lung adenocarcinoma cell line A549 were used to immunize the BALB/c mice. A monoclonal antibody 4E7 (McAb4E7) was produced with hybridoma technique. MTT cell proliferation assay was carried out to evaluate the inhibitory effect of McAb4E7 on A549 cells. Flow cytometric assay, immunohistochemistry, western blot and proteomic technologies based on 2-DE and mass spectrometry were employed to detect and identify the corresponding antigen of McAb4E7.


RESULTS
The monoclonal antibody 4E7 (McAb4E7) specific against A549 cells was produced, which exhibited inhibitory effect on the proliferation of A549 cells. By the proteomic technologies, we identified that ATP synthase beta subunit (ATPB) was the corresponding antigen of McAb4E7. Then, flow cytometric analysis demonstrated the localization of the targeting antigen of McAb4E7 was on the A549 cells surface. Furthermore, immunohistochemistry showed that the antigen of McAb4E7 mainly aberrantly expressed in tumor cellular membrane in non-small cell lung cancer (NSCLC), but not in small cell lung cancer (SCLC). The rate of ectopic expressed ATPB in the cellular membrane in lung adenocarcinoma, squamous carcinoma and their adjacent nontumourous lung tissues was 71.88%, 66.67% and 25.81% respectively.


CONCLUSIONS
In the present study, we identified that the ectopic ATPB in tumor cellular membrane was the non-small cell lung cancer (NSCLC) associated antigen. ATPB may be a potential biomarker and therapeutic target for the immunotherapy of NSCLC.
Lu
Ze-jun
ZJ
Cancer Center and State Key Laboratory of Biotherapy, West China Hospital, West China Medical School, Sichuan University, 37 Guoxue Xiang Street, Chengdu 610041, Sichuan, PR China. luzejun.01@163.com
Song
Qi-fang
QF
Jiang
Sa-sa
SS
Song
Qi
Q
Wang
Wei
W
Zhang
Gao-hua
GH
Kan
Bin
B
Chen
Li-juan
LJ
Yang
Jin-liang
JL
Luo
Feng
F
Qian
Zhi Yong
ZY
Wei
Yu Quan
YQ
Gou
Lan-tu
LT
D000818:Animals; D000911:Antibodies, Monoclonal / Q000096:biosynthesis / Q000737:chemistry / Q000276:immunology; D000918:Antibody Specificity; D014408:Biomarkers, Tumor / Q000032:analysis* / Q000276:immunology; D015153:Blotting, Western; D002289:Carcinoma, Non-Small-Cell Lung / Q000201:enzymology* / Q000276:immunology; D005260:Female; D006801:Humans; D007150:Immunohistochemistry; D008175:Lung Neoplasms / Q000201:enzymology* / Q000276:immunology; D051379:Mice; D008807:Mice, Inbred BALB C; D025261:Mitochondrial Proton-Translocating ATPases / Q000032:analysis* / Q000276:immunology; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization
C506526:ATP5F1B protein, human; D000911:Antibodies, Monoclonal; D014408:Biomarkers, Tumor; D025261:Mitochondrial Proton-Translocating ATPases