Introduction: Pyroptosis induced by lipopolysaccharide (LPS) is a dissolved form of cell death. The molecular marker gasdermin D, specifically GSDMD-N, is critically required for the induction of pyroptosis. Recently, there have been studies showing that LPS is closely related to tumor biology.
Methods: Specimens from 40 patients with colorectal cancer (CRC) were collected. Eight- to twelve-week-old C57BL6 male mice (n=30) were raised. Immunohistochemistry and Western blot were performed to test the expression of GSDMD. Moreover, cytotoxicity assay, IL-18 and IL-1β ELISA, Annexin V and PI stain, and wound healing assay were also made. Gene Expression Profiling Interactive Analysis (GEPIA) was used to verify the expression of GSDMD and overall survival of CRC patients with a high/low expression of GSDMD.
Results: In the research, we showed that the poor prognosis in CRC patients was significantly related to the GSDMD expression and significantly down-regulated in human colorectal cancer (CRC) tissues. Treatment with LPS, but not TNF-α, induced pyroptosis via promoting the expression of GSDMD and GSDMD-N membrane translocation and enhanced chemosensitivity in response to L-OHP in HT29 cells. Furthermore, the enforced expression of GSDMD in HT29 cells reduced cell survival and induced cell death.
Discussion: These results of studies suggest that the low expression of GSDMD correlates with a poor CRC prognosis, and that pyroptosis induced by LPS may improve the anti-cancer effect of L-OHP, inhibiting the tumorigenesis of CRC by activating GSDMD. Our findings lay the foundation for further development of GSDMD serving as an important prognostic biomarker and a valid CRC therapeutic target.
Keywords: colorectal cancer, lipopolysaccharide, chemotherapy, pyroptosis, HT29 cells