Immunotherapeutic effects of recombinant Bacillus Calmette–Guérin containing sic gene in ex vivo and in vivo bladder cancer models

Abstract

Purpose: The recombinant Bacillus Calmette–Guérin (BCG) containing the streptococcal inhibitor of the complement gene (rBCG-sic) may be more resistant to antimicrobial peptides and improve internalization; therefore, it can enhance the immunotherapeutic effect of the BCG. Here we determined the optimal dose of rBCG-sic and compared its effectiveness with that of BCG. Materials and Methods: We fabricated a high-throughput 3D-bioprinted bladder cancer-on-a-chip (BCOC) and used it to evaluate the effectiveness of the rBCG-sic in terms of cell viability, cell migration, and cytokine concentrations. Using an orthotopic mouse model, we evaluated its anticancer effect and toxicity via bioluminescence imaging. Results: T24 cell viability was decreased after treatment with rBCG-sic 30 multiplicities of infection (MOI) versus the same dosage of mock BCG (42.8%±6.4% vs. 75.7%±6.6%, p<0.05). THP-1 cell migration was positively correlated with rBCG-sic concentration (2.42-fold at 30MOI, p<0.01). The interleukin-6 concentration of rBCG-sic 30MOI was significantly higher than that of mock BCG 30MOI (11.2±1.3 pg/mL vs. 6.7±0.6 pg/mL, p<0.05). In the orthotopic bladder cancer mouse model, lower tumor volume was observed in the rBCG-sic 30MOI group than in the BCG 30MOI group after 10 days of treatment (p<0.05). Conclusions: We concluded that rBCG-sic is a useful tool for overcoming BCG unresponsiveness in non-muscle invasive bladder cancer. Additionally, high-throughput BCOC with a microfluidic system can successfully reflect the bladder cancer microenvironment.

Keywords

• antimicrobial peptide
• bacillus calmette–guérin
• bladder cancer
• genetic recombination