TRIM44 regulates tumor immunity in gastric cancer through LOXL2-dependent extracellular matrix remodeling.

PURPOSE: Gastric cancer is a gastrointestinal malignancy with high mortality and poor prognosis, and the molecular mechanism of gastric tumorigenesis remains unclear. TRIM44 has been reported to be involved in tumor development. However, the role of TRIM44 in tumor immunity is largely unknown. METHODS: We analyzed TRIM44 expression in clinical gastric cancer tissues and normal tissues by using western blot, quantitative real-time PCR and bioinformatics analyses. We further investigated the involvement of TRIM44 in tumor immunity in vivo and found that it was dependent on extracellular matrix remodeling. We detected the interaction between TRIM44 and LOXL2 by using immunofluorescence staining and coimmunoprecipitation assays. We observed that TRIM44 mediates the stability of LOXL2 by ubiquitination assays. RESULTS: TRIM44 expression is high and is correlated with T-cell infiltration in gastric cancer. TRIM44 inhibits gastric tumorigenicity by regulating T-cell-mediated antitumor immunity and modulating the protein level of LOXL2. Mechanistically, TRIM44 directly binds to LOXL2 and affects the stability of LOXL2 to change extracellular matrix remodeling and influence tumor immunity. CONCLUSION: These findings demonstrate that TRIM44 regulates the stability of LOXL2 to remodel the tumor extracellular matrix to modulate tumor immunity in gastric cancer and that the TRIM44/LOXL2 complex is a promising biomarker for gastric cancer prognosis and might be a novel immunotherapy target.