ADCY7 dictates N-cadherin stability to inhibit HCC metastasis

<h3>Background & Aims</h3> Hepatocellular carcinoma (HCC), the third leading cause of cancer-related mortality worldwide, remains a therapeutic challenge due to its propensity for early recurrence and metastasis. Our previous study has identified adenylate cyclase 7 (ADCY7), a member of the adenylate cyclase family, as a tumor suppressor in HCC through T cell-dependent immunity. Nevertheless, the exact role and underlying mechanisms of ADCY7 in HCC metastasis remain largely unknown. <h3>Methods</h3> Immunohistochemistry was employed to measure the expression levels of ADCY7 in HCC and its clinical relevance (n = 142). Transwell assay was conducted to examine cell migration and invasion. Tail-vein lung metastasis HCC model was utilized for in vivo experiments. Furthermore, the role of ADCY7 in regulating N-cadherin levels was investigated via qPCR, western blot, immunofluorescence, and co-immunoprecipitation. <h3>Results</h3> Our results demonstrated that ADCY7 functioned as a critical suppressor of HCC metastasis. Clinically, reduced ADCY7 expression correlated with metastatic progression and poor prognosis (<i>P</i> = 0.02) in HCC patients. Functional studies showed that ADCY7 re-expression potently inhibited HCC cell migration (<i>P</i> < 0.0001) and invasion (<i>P</i> < 0.0001) in vitro and attenuated pulmonary metastasis (<i>P</i> < 0.05) in vivo. Mechanistically, ADCY7 served as a molecular scaffold to enhance the interaction between N-cadherin and the E3 ubiquitin ligase SMURF2 (SMAD Specific E3 Ubiquitin Protein Ligase 2), facilitating N-cadherin's K48 linked polyubiquitination at lysine 896 (K896) and promoting its degradation through proteasomal and lysosomal pathways. Importantly, exosomes harboring ADCY7 could be internalized by other HCC cells, suppressing N-cadherin expression and thus reducing metastatic burden. <h3>Conclusions</h3> Collectively, our findings unveil ADCY7 as a metastasis suppressor and highlight its therapeutic potential as a molecular target for combating HCC. <h3>Impact and implications</h3> We have identified ADCY7 and exosomal ADCY7 as potential therapeutic targets for inhibiting HCC metastasis. Our experimental results indicated that ADCY7 could induce the ubiquitination and degradation of N-cadherin by act as a molecular scaffold to enhance the interaction between N-cadherin and the E3 ubiquitin ligase SMURF2, consequently impeding HCC metastasis. Therefore, ADCY7 holds great promise as a therapeutic target for HCC.