SDHA/B reduction promotes hepatocellular carcinoma proliferation by removing cullin1 NEDDylation and stabilizing YAP/TAZ

ABSTRACT: Background & Aims: Succinate dehydrogenase enzyme (SDH) is frequently found to be diminished in Hepatocellular carcinoma (HCC) patient samples, and SDH reduction is associated with elevated succinate level and poor prognosis in HCC patients. But the underlying mechanisms about how impaired SDH activity promotes HCC malignancy remain unclear. Approach & Results: In this study, we observed remarkable downregulations of SDH subunits A and B (SDHA/B) in chronic liver injury-induced murine HCC models and HCC patient samples. Subsequent RNA sequencing, hematoxylin & eosin (H&E) staining and immunohistochemistry (IHC) analyses of HCC samples revealed that Yes-associated protein (YAP) and transcriptional coactivator with PDZ-binding motif (TAZ) were significantly upregulated in HCC, with their levels inversely correlating with that of SDHA/B. The protein stability of YAP/TAZ was greatly enhanced in SDHA/B-depleted HCC cells along with accumulation of succinate. Further mechanistic analyses demonstrated that impaired activity of SDHA/B resulted in succinate accumulation which facilitated the removal of NEDDylation on cullin1, therefore disrupted the E3 ubiquitin ligase SCFβ-TrCP complex, consequently led to YAP/TAZ stabilization and activation in HCC cells. The accelerated in vitro cell proliferation and in vivo tumor growth caused by SDHA/B reduction or succinate exposure were largely dependent on the aberrant activation of YAP/TAZ. Conclusions: Our study demonstrated that SDHA/B reduction promotes HCC proliferation by preventing the proteasomal degradation of YAP/TAZ through modulating cullin1 NEDDylation, thus addicts SDH-deficient HCC cells to YAP/TAZ pathway and renders these cells vulnerable to YAP/TAZ inhibition. Our findings warrant further investigation on the therapeutic effects of targeting YAP/TAZ in HCC patients displaying reduced SDHA/B or elevated succinate levels.

ORGANISM(S): Mus musculus

PROVIDER: GSE207147 | GEO | 2023/05/31

REPOSITORIES: GEO