TRIM25 enhances EGFR stability and signaling activity to promote lung cancer progression

Mutation and amplification of epidermal growth factor receptor (EGFR), one of the most important driver gene, are both reported to participate in the regulation of lung cancer development and progression. Here we investigated the effect and molecular mechanism of tripartite motif 25 (TRIM25) in the regulation of development of lung cancer. CCK-8 and Transwell assays were used to explore the tumor-promoting effect of TRIM25. Results showed that knockdown of TRIM25 significantly inhibited cell proliferation (34% inhibition rate) and invasion (42% inhibition rate). Gene set enrichment analysis (GSEA), Western blot and immunohistochemistry were adopted to detect the effect of TRIM25 on EGFR expression and its downstream signal activity. The results explained that TRIM25 not only up-regulated the expression level of EGFR, but also promoted EGFR signal activation. Co-immunoprecipitation, real-time PCR and cycloheximide (CHX) inhibit protein degradation assays were employed to explore the molecular mechanism of TRIM25 in regulating EGFR stability. Preliminary exploration results indicate that TRIM25 increases the expression level of EGFR and activates its downstream signaling activity through promoting K63-linked ubiquitination of EGFR. Restoration of EGFR expression rescues the phenotype of TRIM25 depletion. In A549 cells, overexpression of EGFR increased cell proliferation rate 1.5-fold and invasion rate 1.6-fold compared with knockdown of TRIM25 cells. Similarly, in H1975 cells, cell proliferation rate was enhanced 2-fold and invasion rate was improved 1.7-fold. These data suggest that TRIM25 promotes lung cancer development via maintaining EGFR stability and continuous EGFR signaling activation. The human lung cancer tissues were obtained from lung cancer patients at Cancer Hospital Chinese Academy of Medical Sciences. Informed consent was obtained from all participants in accordance with the Declaration of Helsinki. The study was approved by the Ethics Committee of the Cancer Hospital Chinese Academy of Medical Sciences.