Objective: Xiaotan Sanjie recipe (XTSJ), a Chinese herbal compound, exerts a significant inhibitory effect on the GC metastasis. Nevertheless, the mechanism underlying the XTSJ-mediated inhibition of GC metastasis is unknown. Our study demonstrated the regulation of XTSJ on the GnT-V-mediated addition of β1,6 GlcNAc branches to E-cadherin and affected GC metastasis in vitro and in vivo.
Methods: The effect (and associated mechanism) of XTSJ on GC metastasis was evaluated in vitro (using GC cell lines) and in vivo (using a GC mouse model) by focusing on the expression of GnT-V (encoded by MGAT5).
Results: We demonstrated that the migration and invasion ability of GC cells decreased significantly after XTSJ administration, which confirmed the efficacy of XTSJ in treating GC in vitro. Moreover, we showed that XTSJ increased the accumulation of E-cadherins at junctions between GC cells, an effect which was reversed by MGAT5 overexpression. XTSJ administration and MGAT5 knockdown alleviated the structural abnormality of the cell-cell junctions, while MGAT5 overexpression had the opposite effect. MGAT5 knockdown and XTSJ treatment also significantly increased the accumulation of proteins associated with the E-cadherin-mediated adherens junction complex. Furthermore, the expression of MGAT5 was significantly lower in the lungs of BGC-823-MGAT5+XTSJ mice than in those of BGC-823-MGAT5+solvent mice, indicating that the ability of gastric tumors to metastasize to the lung was decreased in vivo following XTSJ treatment.
Conclusion: Our study confirmed that XTSJ prevented GC metastasis by inhibiting the GnT-V-mediated E-cadherin glycosylation and promoting E-cadherin accumulation at cell-cell junctions.