miR-29a-SIRT1-Wnt/β-Catenin Axis Regulates Tumor Progression and Survival in Hepatocellular Carcinoma

Sirtuin 1 (SIRT1) participates in the initiation and evolution of hepatocellular carcinoma (HCC). However, the specific mechanism of SIRT1 in HCC remains unclear. The mRNA expression of miR-29a in HCC were identified by qRT-PCR. miR-29a mimic and inhibitor were employed. The alteration of biological behavior was evaluated by Cell Counting Kit-8 (CCK8), clone formation, transwell and wound-healing assay. SIRT1 was verified to be a target gene which directly regulated by miR-29a. Luciferase reporter assay and co-IP were employed to evaluate the direct binding of miR-29a and SIRT1. Animal model was used to evaluate its function on tumor growth and metastasis in vivo. The relationship between miR-29a/SIRT1 and prognosis of HCC patients was analyzed. SIRT1 overexpression accompanied by low expression of miR-29a were detected in HCC which was negatively correlated, and associated with overall survival, vascular invasion and TNM stage. Up-regulation of miR-29a suppressed cell growth and motility. Deprivation of miR-29a expression led to opposite effect. The direct binding of miR-29a to SIRT1 was confirmed by luciferase reporter assay and co-IP. miR-29a repressed SIRT1, DKK2 and β-catenin, but their expression was obviously elevated by miR-29a inhibitor. Animal model suggested miR-29a could reduce the expression of SIRT1, thereby inhibiting HCC growth and metastasis by inactivating Wnt/β-catenin pathway. Low expression of miR-29a and high expression of SIRT1 predicted shorter survival time in HCC patients. miR-29a had the function of tumor suppressor which directly inhibited oncogenic SIRT1. The loss of miR-29a led to up-regulation of SIRT1, aggravate malignant transformation and poor prognosis of HCC.