Diphyllin, a SPP1/DKK1 inhibitor, restricts hepatocellular carcinoma growth by modulating sugar and bile acid metabolism

Background: Hepatocellular carcinoma (HCC) is a prevalent solid tumor with high global incidence and mortality rates. The overexpression of tumor-derived SPP1 and DKK1 is implicated in the malignant progression of HCC, poor prognosis and resistance to chemotherapy. Inhibitors targeting tumor-derived SPP1 and DKK1 thus represents a promising strategy for cancer therapy.

Methods: Molecular docking was used to screened out the inhibitors of SPP1/DKK1 from herbal databases. In vitro and in vivo experiments were performed to determine the anticancer effect of diphyllin on HCC. To further elucidate the underlying mechanism of diphyllin against HCC, RNA-Sequencing and metabolomics were performed to analyse the alteration of genes and meatbolic pathways.

Results: We discovered a natural molecule, diphyllin, can suppress the expression of both SPP1 and DKK1. Diphyllin was found to induce apoptosis in HepG2 and Hepa1-6 while suppressing cell proliferation, migration, and invasion. Mechanistically, diphyllin appears to reprogram sugar metabolism and inhibit bile acid synthesis by regulating the HIF-1 pathway in liver cancer cells, leading to the enhancement of the cellular stress response. These mechanisms collectively promote apoptotic cell death and reduce cell proliferation. Furthermore, the combination of diphyllin with sorafenib demonstrated significant synergistic anti-tumor activity in vitro.

Conclusions:  In summary, our findings highlight diphyllin as a promising natural inhibitor of SPP1/DKK1, effectuating robust anti-tumor effects potentially through the inhibition of bile acid synthesis and the reprogramming sugar metabolism, which enhances the cellular stress response and promotes apoptotic cell death, leading to the suppression of growth on HCC.