Ailanthone Enhances Gastric Cancer Cell Apoptosis Through Inducing DNA Damage and Repressing Base Excision Repair Via Downregulating P23

Abstract Background: Chemotherapy plays an irreplaceable role in the treatment of gastric cancer (GC), but currently available chemotherapeutic drugs are not ideal. Medicinal plants are an important direction for new drug discovery. Methods: We combined literature collection, organoid drug screening and PDX verification to search for new, effective drugs. The effect of AIL on the GC cells was investigated by CCK-8 assays, Colony Formation Assay and Cell Viability, Cell migration and invasion assay and PDX mice model. The expression of indicated RNA and proteins were measured by qRT-PCR ,IHC and western blotting. The proteins HSP90 binding to P23 or XRCC1 were identified by Co-IP. Results: Through drug screening of GC organoids, we had determined that ailanthone (AIL) has an anticancer effect on GC cells in vitro and in vivo. We also found that AIL promoted apoptosis of GC cells through flow cytometry analysis and the expression of caspase 3 and H2AX were significantly enhanced by AIL in GC cells and tumor tissues, suggesting that AIL can induce DNA damage and apoptosis of GC cells. Further transcriptome sequencing of the PDX tissue indicated that AIL inhibited the expression of XRCC1 which plays an important role in DNA damage repair, and the results were also confirmed by western blotting. In addition, we found that AIL inhibited the expression of P23 and inhibition of P23 decreased the expression of XRCC1 through western blotting analysis, indicating that AIL can regulate XRCC1 via P23. The results of co-immunoprecipitation showed that AIL can inhibit the binding of P23 and XRCC1 to HSP90 respectively.Conclusion: These findings indicate that AIL can induce DNA damage and apoptosis of GC cells. Meanwhile, AIL can decrease XRCC1 by downregulating P23 to inhibit DNA damage repair. The present study shed light to the new drug isolated from natural medicinal plants for GC therapy.