MP01: Bladder Cancer: Basic Research & Pathophysiology I
MP01-02: Sulfasalazine could modulate the CD44v9-xCT system and enhance CDDP-induced cytotoxic effects in metastatic bladder cancer; A novel therapeutic strategy for metastatic bladder cancer
Introduction: The development of a new therapeutic strategy against cisplatin (CDDP) resistant metastatic bladder cancer is strongly warranted. Recently, sulfasalazine (SSZ), widely used for the treatment of ulcerative colitis, has been reported to regulate CD44v9, a variant isoform of CD44 which is thought to be a cancer stem cell modulator and thereby to induce intracellular reactive oxygen species (ROS) production. We examined whether SSZ could enhance CDDP-induced cytotoxicity through increased ROS production using a lung metastatic bladder cancer model.
Methods: Cytotoxic effects, intracellular ROS production, and CD44v9 as well as phosho-p38MAPK protein expression after exposure to SSZ with or without CDDP were assessed in MBT-2V cells, which is murine bladder cancer cell line and have a high lung metastatic potential. In an in vivo study, lung tumors were generated by injecting MBT-2V cells into the tail vein of C3H/HeN mice on day 0. Intraperitoneal administration of SSZ (500 mg/kg, 2-days on/1-days off) or saline with or without CDDP (2 mg/kg, 1-day on/ 4-days off) was started on day 3.
Results: SSZ (100µM-800µM) was observed to have dose-dependent cytotoxic effects in MBT-2V cells. The relative cell viability of combination of SSZ (300µM) and CDDP (10µM) was 40.7±3.1%, which was significantly lower than SSZ alone (83.1±5.4%, p<0.001), CDDP alone (69.8±3.0%, p<0.001), or vehicle control (100%, p<0.001). The ROS production in MBT-2V cells treated with combination of SSZ (300µM) and CDDP (10µM) was 16669.9±450.1 arbitrary units, which was significantly higher than that in cells treated with SSZ alone (10244.6±1902.7 arbitrary units, p=0.021), CDDP alone (6306.1±1081.2 arbitrary units, p=0.007), or vehicle control (3787±229.1 arbitrary units, p<0.001). Lower protein expression of CD44v9 and higher protein expression of phosho-p38MAPK were observed after the combination of SSZ with CDDP as compared to SSZ or CDDP alone. In the MBT-2V murine lung metastatic BC model (n=10 in each group), the number of metastatic lung nodules in mice treated with the combination of SSZ with CDDP was 15.5±10.8, which was significantly lower than that in mice treated with vehicle control (114.3±37.9, p<0.001), SSZ alone (50.6±19.1, p<0.01), or CDDP alone (69.2±30.9, p<0.01).
Conclusions: SSZ could induce ROS production and enhance CDDP-induced cytotoxic effects. The combination of SSZ with CDDP might be a novel therapeutic modality against metastatic bladder cancer. Source of
