Resibufogenin and Oxaliplatin Synergistically Inhibit Diffuse Gastric Cancer by Inactivating the FAK/AKT/GSK3β/β-Catenin Signaling Pathway.

Background: Diffuse Gastric Cancer (DGC) is a highly aggressive form of gastric cancer with a poor prognosis. Oxaliplatin (OX) is one of the first-line chemotherapeutic agents for the treatment of gastric cancer. However, some patients with DGC do not benefit from OX therapy. Resibufogenin (RBF), one of the main active components of the Chinese medicine Huachansu, has demonstrated significant anti-cancer effects. Nevertheless, the potential of RBF to enhance the sensitivity of OX treatment in DGC and its underlying mechanisms have not been reported.

Objective: The aim of this study is to investigate the sensitizing effect of RBF on OX therapy for DGC, as well as to elucidate the potential targets and mechanisms of action. This exploration is of significant importance for the development of sensitizers that can improve the therapeutic efficacy of OX and for the advancement of patentable innovations in this field.

Methods: MTT assay, flow cytometry, Western blotting, and immunofluorescence assays were employed to assess the inhibitory effects of Resibufogenin (RBF) in combination with OX on DGC in vitro. Human DGC cell xenografts were established in a mouse model to evaluate the efficacy and safety of RBF and OX for treating DGC in vivo.

Results: It was found that RBF inhibited the proliferation of DGC cells in a time- and dose-dependent manner. When RBF was used in combination with OX, the sensitivity of DGC cells to OX was improved. Significantly, the combination of OX and RBF acts synergistically to induce apoptosis and autophagy while inhibiting migration and invasion of DGC cells in vitro. In vivo, the combination of OX and RBF dramatically inhibited the progression of DGC in the subcutaneous xenograft model without observable toxicity. Mechanistically, RBF significantly inhibited the expression and activation of FAK. OX and RBF synergistically inhibited the phosphorylation of FAK, AKT, and GSK3β to abrogate the entry of β-catenin into the cell nucleus.

Conclusion: RBF exhibits a pronounced suppressive effect on FAK, and its combination with OX synergistically blocks the FAK/AKT/GSK3β/β-catenin signaling cascade, thereby inhibiting the growth and metastasis of DGC. This study provides a novel avenue for future research and patent development of FAK inhibitors, with the potential to enhance the therapeutic efficacy of DGC treatment and overcome drug resistance.