Obovatol inhibits proliferation, invasion and immune escape of hepatocellular carcinoma cells through modulating the JAK/STST3/PD-L1 pathway.

Background: Hepatocellular carcinoma (HCC) is a common cancer that is fatal and has a dismal prognosis. Obovatol (Ob), a novel lignan derived from the leaf and stem bark of Magnolia obovata Thunb, has exhibited anti-tumor effect on diverse tumors. However, its effect and mechanisms on HCC remain to be further explored.

Methods: Huh7 and Hep3B cells, as well as BALB/c nude mice were used to determine the function and mechanisms of Ob on growth, invasion and immune escape by cell counting kit-8, transwell, enzyme-linked immunosorbent assay (ELISA) and western blot experiments.

Results: Ob reduced the cell viability of Huh7 and Hep3B cells, with a IC50 value of 57.41 µM and 62.86 µM, respectively. Ob declined the invasion ability, the protein expression of N-cadherin and the concentrations of IL-10 and TGF-β, whereas increased the E-cadherin expression and the contents of IFN-γ and IL-2 in Hep3B and Huh7 cells. Mechanically, Ob decreased the protein level of p-JAK/JAK, p-STAT3/STAT3 and PD-L1, which was partly restored with the treatment of RO8191, an activator of JAK/STAT3 axis. The effect of Ob on the cell viability, the invasion ability, the protein level of N-cadherin and E-cadherin, and the concentrations of IL-10, TGF-β, IFN-γ and IL-2 in both Hep3B and Huh7 cells was reversed with the management of RO8191. In vivo, Ob reduced tumor volume and weight, the level of N-cadherin, PD-L1, p-JAK/JAK, and p-STAT3/STAT3, with an elevated expression of E-cadherin and IFN-γ.

Conclusion: Ob downregulated the JAK/STST3/PD-L1 pathway to attenuate the growth, invasion and immune escape of HCC.