MMP9 Knockout by CRISPR-Cas9 Reduces Bladder Cancer Malignancy But Does Not Synergize With BCG and Anti-PD-L1 in an Orthotopic Mouse Model.

Bladder cancer (BC) is the 10th most common cancer worldwide, accounting for approximately 5% of new cases. Several factors contribute to tumor progression, including increased MMP9. Recently, CRISPR-Cas9 and immunotherapy have offered high specificity for treatments; therefore, we edited MMP9 using CRISPR-Cas9 methodology to inhibit metastatic mechanisms and evaluated potential synergy with BCG and anti-PD-L1 therapy. We performed CRISPR-Cas9 gene editing using an RNP complex in the MB49 murine BC cell line. Gene expression of MMPs, integrins, and BAX was analyzed, along with protein expression. Cells were divided into a Scramble control group and CRISPR-Cas9 for the MMP9 edited group (MMP9-/-). Female C57BL/6 mice received orthotopic BC cells (scramble and MMP9-/- groups) treated with BCG and anti-PD-L1. Statistical analyses were performed using t test or ANOVA. MMP9 gene and protein expression were reduced in the MMP9-/- group compared with the scramble group. No differences were observed in other MMPs. Decreased ITGB3, increased BAX gene expression, as well as reduced migration and adhesion to ECM were observed in the MMP9-/- group. Animals in the scramble group showed greater weight loss and lower survival than treated groups. Overall, MMP9 modulated key cellular mechanisms, but did not show synergistic effects with BCG and anti-PD-L1 in vivo.