NUP37 accumulation mediated by TRIM28 enhances lipid synthesis to accelerate HCC progression

Elevated intracellular lipid synthesis is important for hepatocellular carcinoma (HCC) progression. Our study aimed to identify the role of nucleoporin 37 (NUP37) in lipid synthesis and HCC progression. The expression of NUP37 was significantly upregulated in HCC and associated with a poor prognosis. NUP37 silencing suppressed lipid synthesis, proliferation, migration, and invasion of HCC cells in vitro, and restrained tumor growth in xenograft mouse models in vivo. Next, we found the high expression of NUP37 in HCC was related to post-translational modifications. Tripartite motif-containing 28 (TRIM28) was identified as an interacting protein of NUP37 and upregulated its protein level. The subsequent analysis revealed that TRIM28-mediated SUMOylation of NUP37 at Lys114/118/246 inhibited K27-linked polyubiquitination of NUP37, which is one reason for its high expression level in HCC. In conclusion, TRIM28 SUMOylates NUP37 to prevent its ubiquitination and proteasomal degradation, increasing the stability of the NUP37 protein, thereby promoting lipid synthesis and the progression of HCC.