TMED2 promotes thyroid cancer tumorigenesis by being involved in mTORC1-mediated fatty acid metabolism.

[BACKGROUND] TMED2, a p24 family member, has been implicated in the progression of multiple cancers. However, its function in thyroid cancer (THCA) is unclear and needs to be clarified.

[METHODS] TMED2 expression was first explored using single-cell datasets and the TCGA database, followed by validation in THCA tissues and cell lines by immunohistochemistry (IHC), western blot, and qRT-PCR. Survival analysis was performed to evaluate the correlation between TMED2 expression and patient survival. The impact of TMED2 on THCA cells was analyzed using CCK-8, EdU staining, wound healing, Transwell, and flow cytometry assays. The lipid droplet accumulation was detected using BODIPY staining. The expression of key enzymes involved in fatty acid (FA) synthesis was assessed using western blot assay. Rescue experiments were conducted to investigate the mechanism of TMED2. Finally, the role of TMED2 in vivo was assessed in a nude mouse model.

[RESULTS] TMED2 expression was significantly upregulated in THCA tissues and four cell lines and was closely related to worse outcomes. Functional experiments revealed that TMED2 enhanced proliferation, migration, invasion, and FA synthesis in THCA cells, while suppressing cell apoptosis. Mechanistically, TMED2 promoted tumor growth and FA synthesis in THCA by affecting the activation of mTORC1 signaling, which was also observed in a xenograft mouse model.

[CONCLUSIONS] Our results demonstrated that TMED2 may function as an oncogene to support THCA growth by affecting mTORC1-mediated FA synthesis. These findings suggest that TMED2 could serve as a potential target for THCA treatment.