Introduction of 65 kDa antigen of Mycobacterium tuberculosis to cancer cells enhances anti-tumor effect of BCG therapy.
Bacillus Calmette Guerin (BCG) immunotherapy has anti-tumorigenic effects against bladder cancer. To improve the efficacy of BCG therapy, we introduced the gene encoding the 65 kDa heat shock protein (hsp) of Mycobacterium tuberculosis into a mouse malignant melanoma cell line (B16). An expression vector harboring the 65 kDa antigen gene was transfected into B16 using Lipofectamine, then expression of the antigen was confirmed by RT-PCR and Western blotting. Several cell lines expressing 65 kDa antigen were established (B16/65 kDa). We also established a control cell line transfected with the vector alone (B16/con). All cell lines (B16, B16/con, B16/65 kDa) were injected intraperitoneally into syngeneic mice with or without BCG prior immunization and the development of tumor ascites was examined. To analyze the mechanism of the anti-tumor effect, CD4 T cells or CD8 T cells were depleted in vivo by administering the corresponding monoclonal antibody. B16/65k Da expressed the 65 kDa hsp of M. tuberculosis. The tumor growth of B16/65 kDa was slightly retarded in naive mice, but significantly inhibited by BCG. The anti-tumor effect was totally abrogated in mice deficient in CD4 T cells, suggesting that CD4 T cells are involved in this process. The 65 kDa hsp of M. tuberculosis was expressed after gene transduction in a malignant melanoma cell line and significantly enhanced the anti-tumor effect of BCG immunotherapy. CD4 T cells play an important role in this anti-tumor effect.
Hara
Isao
I
Divisiont of Urology, Kobe University Graduate School of Medicine, Japan. hara@med.kobe-u.ac.jp
Sato
Noriyuki
N
Miyake
Hideaki
H
Muramaki
Mototsugu
M
Hikosaka
Satoko
S
Kamidono
Sadao
S
D000818:Animals; D001500:BCG Vaccine / Q000008:administration & dosage* / Q000276:immunology; D001426:Bacterial Proteins / Q000235:genetics / Q000276:immunology* / Q000378:metabolism; D045744:Cell Line, Tumor; D018834:Chaperonin 60; D018833:Chaperonins / Q000235:genetics / Q000276:immunology* / Q000378:metabolism; D007167:Immunotherapy / Q000379:methods*; D007274:Injections, Intraperitoneal; D008545:Melanoma / Q000473:pathology / Q000517:prevention & control*; D051379:Mice; D008810:Mice, Inbred C57BL; D009169:Mycobacterium tuberculosis / Q000276:immunology; D009368:Neoplasm Transplantation / Q000473:pathology; D009374:Neoplasms, Experimental / Q000503:physiopathology / Q000517:prevention & control*; D014162:Transfection; D014185:Transplantation, Isogeneic / Q000473:pathology
D001500:BCG Vaccine; D001426:Bacterial Proteins; D018834:Chaperonin 60; C074119:heat-shock protein 65, Mycobacterium; D018833:Chaperonins