Focused ultrasound restrains the growth of orthotopic colon cancer via promoting pyroptosis.

Introduction: Focused ultrasound (FUS) is a non-invasive tumor therapy technology emerging in recent years, which can treat various solid tumors. However, it is unclear whether FUS can affect the pyroptosis of colon cancer (CC) cells. Here, we analyzed the effect of FUS on pyroptosis in the orthotopic CC model.

Material and methods: After an orthotopic CC mouse model was constructed by injecting CT26-Luc cells, BABL/C mice were allocated to the normal, tumor, FUS, and FUS + BAY11-7082 (pyroptosis inhibitor) groups. We monitored the tumor status of the mice through in vivo fluorescence image analysis. The histopathological injury of the intestinal tissue and the expression of IL-1β, IL-18, caspase-recruitment domain (ASC), cleaved caspase-1, gasdermin D (GSDMD), and NLRP3 of the CC tumors were examined utilizing hematoxylin and eosin staining, immunohistochemical assay, and Western blot.

Results: FUS restrained the fluorescence intensity of the tumors in orthotopic CC mice, while FUS-mediated suppression of the bioluminescent signal of the tumors was alleviated by BAY11-7082. FUS was found to relieve the injury of the intestinal tissues in CC mice as revealed by morphology. Furthermore, the expressions of IL-1β, IL-18, GSDMD, ASC, cleaved caspase-1, and NLRP3 of the CC tumors in the FUS group were higher than those in the tumor group, while BAY11-7082 addition partly reversed the FUS's effects on orthotopic CC model mice.

Conclusions: Our results pointed out that FUS presented anti-tumor activity in experimental CC, and its mechanism was correlated with the promotion of pyroptosis.