Investigation of active Bacillus Calmette-Guérin (BCG) component on bladder cancer cell line

Abstract

AIM: Intravesical Bacillus Calmette-Guérin (BCG) therapy is an effective treatment for superficial bladder cancer. However, its frequent and severe side-effects were major obstacles for clinical setting. In this study, BCG was fractionized with simple methods to find an active component.
METHODS: Sonicated or autoclaved Tokyo 172 BCG strain was fractionated to supernatant and precipitate. These fractions were co-cultured with 5637 human bladder cancer cell line (5637 cell). The growth inhibitory effect on 5637 cell was analyzed by dye exclusion test. ³H-thymidine incorporation, cytologic examination with Giemsa staining, and cell cycle analysis using flowcytometry.
RESULTS: Live BCG and supernatant fractions obtained by sonication or autoclave suppressed the growth of 5637 cell. The dark-stained spots suggesting early phase apoptosis were found in nuclei of 5637 cells by co-cultured with live BCG or supernatant fractions. In these cells, the ratios of apoptotic cells were increased compared with non­ treated cells.
CONCLUSION: These results suggest that BCG has a direct anti-tumor effect to induce apoptosis on 5637 cell. Supernatant fractions obtained by sonication or autoclave maintained the direct anti-tumor effects as well as live BCG. Further purification of these fractions may provide a new BCG derivatives which has higher efficacy with reduced toxicity.