Circadian gene Cry1 inhibits the tumorigenicity of hepatocellular carcinoma by the BAX/BCL2-mediated apoptosis pathway

Hepatocellular carcinoma (HCC) is a leading cause of cancer-related mortality worldwide, and emerging evidence implicates circadian rhythm disruption in its pathogenesis. Here, we identified the core circadian gene Cryptochrome1 ( Cry1 ) as a potential tumor suppressor in HCC. Clinical analysis revealed that low Cry1 expression correlated with poor prognosis, showing a median survival of 36 vs 47 months, and Cry1 expression was significantly reduced in HCC cell lines (0.6-fold in SMMC-7721 vs LO2). Functional studies demonstrated that Cry1 overexpression reduced proliferation by 30% with more cells in the G1 phase, as well as inhibited migration/invasion, while Cry1 knockdown increased proliferation by 50% with less cells in the G1 phase and increased migration/invasion. Finally, we found Cry1 depletion downregulated pro-apoptotic BAX and upregulated anti-apoptotic BCL2, while Cry1 overexpression produced the opposite effects, suggesting its role in apoptosis via the BCL2/BAX-mediated apoptosis pathway. These findings indicate that Cry1 acts as a tumor suppressor in HCC, providing insights into the circadian dysfunction-cancer pathogenesis connection and its potential as a diagnostic biomarker and therapeutic target requires further verification through preclinical and clinical investigations in the future.