TRIM26 inhibits clear cell renal cell carcinoma progression through destabilizing ETK and thus inactivation of AKT/mTOR signaling.

ABSTRACT

BACKGROUND: Tripartite motif-containing 26 (TRIM26), a member of the TRIM protein family, exerts dual function in several types of cancer. Nevertheless, the precise role of TRIM26 in clear cell renal cell carcinoma (ccRCC) has not been investigated. METHODS: The expression of TRIM26 in ccRCC tissues and cell lines were examined through the use of public resources and experimental validation. The impacts of TRIM26 on cell proliferation, migration, invasion, and epithelial-mesenchymal transition (EMT) process were determined via CCK-8, colony formation, EdU incorporation, wound healing, Transwell invasion, Western blot, and Immunofluorescence assays. RNA-seq followed by bioinformatic analyses were used to identify the downstream pathway of TRIM26. The interaction between TRIM26 and ETK was assessed by co-immunoprecipitation, qRT-PCR, Western blot, cycloheximide (CHX) chase, and in vivo ubiquitination assays. RESULTS: We have shown that TRIM26 exhibits a downregulation in both ccRCC tissues and cell lines. Furthermore, this decreased expression of TRIM26 is closely linked to unfavorable overall survival and diseases-free survival outcomes among ccRCC patients. Gain- and loss-of-function experiments demonstrated that increasing the expression of TRIM26 suppressed the proliferation, migration, invasion, and EMT process of ccRCC cells. Conversely, reducing the expression of TRIM26 had the opposite effects. RNA sequencing, coupled with bioinformatic analysis, revealed a significant enrichment of the mTOR signaling pathway in the control group compared to the group with TRIM26 overexpression. This finding was then confirmed by a western blot assay. Subsequent examination revealed that TRMI26 had a direct interaction with ETK, a non-receptor tyrosine kinase. This interaction facilitated the ubiquitination and degradation of ETK, resulting in the deactivation of the AKT/mTOR signaling pathway in ccRCC. ETK overexpression counteracted the inhibitory effects of TRIM26 overexpression on cell proliferation, migration, and invasion. CONCLUSION: Our results have shown a novel mechanism by which TRIM26 hinders the advancement of ccRCC by binding to and destabilizing ETK, thus leading to the deactivation of AKT/mTOR signaling. TRIM26 shows promise as both a therapeutic target and prognostic biomarker for ccRCC patients.