Angiopoietin-like protein 8 (betatrophin) may inhibit hepatocellular carcinoma through suppressing of the Wnt signaling pathway.

Objectives: Hepatocellular carcinoma (HCC) is one of the leading fatal neoplasms and the most common primary liver malignancy worldwide. Peptide hormone ANGPTL8 (betatrophin) may act as an important regulator in HCC development through the Wnt/β-catenin pathway. We aimed to evaluate the effects of recombinant ANGPTL8 on Wnt/β-catenin signaling in human liver carcinoma cells (HepG2) and their viability.

Materials And Methods: The expression of ANGPTL8 was conducted in the pET-21b-E. coli Bl21 (DE3) system and the produced peptide was purified. HepG2 cells were treated with different concentrations of ANGPTL8 (25, 50, 100, 150, 200, and 250 ng/ml) for 24, 48, and 72 hr. MTT assay was performed to detect the viability of treated cells, and apoptotic induction by ANGPTL8 was measured by flow cytometry assay. Finally, using qRT-PCR the mRNA levels of Wnt signaling modulators WIF-1 and β-catenin were evaluated in treated cells.

Results: MTT assay showed that ANGPTL8 inhibits proliferation of HepG2 cells moderately in a time-independent manner. The highest concentration of the ANGPTL8, 250 ng/ml, reduced cell proliferation after 24, 48, and 72 hr similarly about 30%. In the same concentration of ANGPTL8, after 24 hr of treatment flow cytometry assay revealed a mild increase in early and late apoptosis up to 7.7 and 14.3%, respectively. The qRT-PCR showed that in a concentration-dependent and time-independent fashion, the expression of WIF-1 and β-catenin genes respectively increased and decreased significantly (<0.05).

Conclusion: Our findings suggest that ANGPTL8 may act as a moderate suppressor against HCC cell proliferation possibly via affecting Wnt signaling modulators.