Disrupting CCDC137-mediated LZTS2 and β-TrCP interaction in the nucleus inhibits hepatocellular carcinoma development via β-catenin and AKT.

Hepatocellular carcinoma (HCC) is a highly heterogeneous solid tumor, with its biological characteristics intricately linked to the activation of oncogenes. This research specifically explored CCDC137, a molecule within the CCDC family exhibiting the closest association with HCC. Our investigation aimed to unravel the role, underlying mechanisms, and potential therapeutic implications of CCDC137 in the context of HCC. We observed a close correlation between elevated CCDC137 expression and poor prognosis in HCC patients, along with a promotive effect on HCC progression in vitro and in vivo. Mechanistically, we identified LZTS2, a negative regulator of β-catenin, as the binding protein of CCDC137. CCDC137 facilitated K48-linked poly-ubiquitination of LZTS2 at lysine 467 via recruiting E3 ubiquitin ligase β-TrCP in the nucleus, triggering AKT phosphorylation and activation of β-catenin pathway. Moreover, the 1-75 domain of CCDC137 was responsible for the formation of the CCDC137-LZTS2-β-TrCP complex. Subsequently, designed peptides targeting the 1-75 domain of CCDC137 to disrupt CCDC137-LZTS2 interaction demonstrated efficacy in inhibiting HCC progression. This promising outcome was further supported by HCC organoids and patient-derived xenograft (PDX) models, underscoring the potential clinical utility of the peptides. This study elucidated the mechanism of the CCDC137-LZTS2-β-TrCP protein complex in HCC and offered clinically significant therapeutic strategies targeting this complex.