DPEP1 is a direct target of miR-193a-5p and promotes hepatoblastoma progression by PI3K/Akt/mTOR pathway

Hepatoblastoma (HB) is the most common hepatic neoplasm in childhood and the therapeutic outcomes remain undesirable due to its recurrence and metastasis. Increasing evidence shows that dipeptidase 1 (DPEP1) has pivotal function in tumorigenesis in multiple tumors. However, the expression pattern, biological function, and underlying mechanism of DPEP1 in HB have not been reported. Here we showed that DPEP1 was significantly upregulated and was associated with poor prognosis in HB patients. In vitro and in vivo assays indicated that silencing DPEP1 significantly suppressed HB cell proliferation, migration, and invasion, while DPEP1 overexpression exhibited the opposite effect. In addition, we identified that DPEP1 was a direct target of microRNA-193a-5p (miR-193a-5p). Functional experiments demonstrated that overexpression of miR-193a-5p significantly inhibited cell proliferation and invasion of HB cells, while the inhibitory effect could be reversed by DPEP1 overexpression. Moreover, miR-193a-5p was decreased in HB tumor tissues and associated with a poor clinical prognosis. Mechanistically, our results indicated that the miR-193a-5p/DPEP1 axis participated to the progression of HB via regulating the PI3K/Akt/mTOR (phosphatidylinositol-3-kinase/Akt/mammalian target of rapamycin) signaling. In conclusion, our findings suggest that the miR-193a-5p /DPEP1 axis might be a good prognostic predictor and therapeutic target in HB.