Immunotherapy for orthotopic murine bladder cancer using bacillus Calmette-Guerin recombinant protein Mpt-64.
OBJECTIVE
We investigated the efficacy of the recombinant bacillus Calmette-Guerin subunit protein vaccine Mpt-64 for inducing cytokine production and suppressing orthotopic bladder tumor growth in mice.


METHODS
One mycobacteria candidate gene (Mpt-64) was cloned and ligated into eukaryotic expression vectors. The induction and efficiency of Mpt-64 protein expression were detected using Western blotting. Various doses of Mpt-64 proteins were instilled intravesically 6 times in 2 weeks after intravesical implantation of MBT-2 tumor cells in chemical injured urothelium. Systemic cytokine responses, tumor growth and cumulative survival rates were monitored.


RESULTS
In vitro expression of recombinant Mpt-64 subunit protein was efficient in our system. Mice treated with 100 and 200 microg Mpt-64 subunit proteins significantly inhibited orthotopic MBT-2 tumor growth in C3H/HeN mice compared with that in control and 50 microg treatment groups in terms of the tumor taking rate, bladder tumor burden and mortality rate. Meanwhile, marked increased serum interferon-gamma with a limited but significant increase in serum interleukin-2 was observed in mice treated with 100 and 200 microg Mpt-64 proteins compared with control and 50 microg treated groups.


CONCLUSIONS
A highly immunopotent recombinant Mpt-64 subunit protein of bacillus Calmette-Guerin was produced and it elicited immune responses with a high serum interferon-gamma level, inhibited orthotopic tumor growth and prolonged survival in tumor bearing mice. Thus, intravesical immunogenic therapy using recombinant Mpt-64 protein may be an alternative bacillus Calmette-Guerin regimen for superficial bladder cancer.
Yu
Dah-Shyong
DS
Uro-Oncology Laboratory, Division of Urology, Department of Surgery, Tri-Service General Hospital, Taipei, Taiwan, Republic of China. yuds@ms21.hinet.net
Lee
Chi-Feng
CF
Chang
Sun-Yran
SY
D000818:Animals; D000942:Antigens, Bacterial / Q000627:therapeutic use*; D005260:Female; D007167:Immunotherapy; D051379:Mice; D008809:Mice, Inbred C3H; D011994:Recombinant Proteins / Q000627:therapeutic use; D001749:Urinary Bladder Neoplasms / Q000188:drug therapy*
D000942:Antigens, Bacterial; C510537:MPT64 protein, Mycobacterium tuberculosis; D011994:Recombinant Proteins