βKlotho, a direct target of miR-206, contributes to the growth of hepatoblastoma through augmenting PI3K/Akt/mTOR signaling.

Hepatoblastoma (HB) is the most frequent pediatric liver malignancy. However, the treatment outcome for patients with advanced-stage HB remains unsatisfactory. Accumulating evidence indicates that βKlotho (KLB) acts as an oncogene or a tumor-suppressor gene in a context-dependent manner. Despite this, the expression profile and effects of KLB on the growth of HB are still elusive. This study aimed to explore the effect of miR-206/KLB axis on HB growth. The expression of KLB was explored in HB cells (HepG2 and HuH6) and tissues using quantitative polymerase chain reaction (qPCR), Western blot analysis, and immunohistochemistry. Besides, miR-206 expression was determined in HB cells and tissues using qPCR and fluorescence in situ hybridization. The prognostic value of KLB or miR-206 in our patients with HB was investigated using the Kaplan-Meier method. The biological effects of KLB or miR-206 on HB cells were identified in vitro. The proliferative effects of KLB on HuH6 cells were also investigated in vivo. Moreover, the mechanical signaling of KLB in HB was determined through bioinformatics analysis followed by experimental validation. The results showed a significant upregulation of KLB in HB tissues and cells. Elevated level of KLB was found to be significantly correlated with the aggressive phenotype and poor overall survival for children with HB. The in vitro function assay demonstrated that KLB knockdown promoted apoptosis and suppressed the proliferation, migration, and invasion of HB cells. Besides, KLB knockdown inhibited the proliferation of HuH6 cells in vivo, while KLB overexpression had the opposite effect. Furthermore, KLB was proved to be the direct target of miR-206. Low level of miR-206 served as an independent risk factor for poor prognosis in children with HB. The overexpression of miR-206 negatively regulated the aggressive biological behaviors of HB cells, which was partially rescued by KLB overexpression. Mechanically, the miR-206/KLB axis played a vital role in HB growth through augmenting the phosphatidylinositol 3-kinase (PI3K)/Akt/mammalian target of rapamycin (mTOR) signaling. In conclusion, the data demonstrated that the miR-206/KLB axis might serve as an important biomarker/therapeutic target for HB.