Anticancer Drug Discovery And Activity Evaluation Targeting 3-Phosphoglycerate Dehydrogenase(PHGDH)

Recent studies in understanding the relationship between cancer and metabolism have highlighted the importance of the serine synthesis pathway(SSP)consisting of three consecutive enzymatic reactions.Homo sapiens 3-phosphoglycerate dehydrogenase(PHGDH)catalyzes the first committed step for the synthesis of glucose-derived serine via the SSP and has been associated with a wide variety of cancers,including breast cancer,melanoma,colon cancer,glioma,nasopharyngeal carcinoma,cervical adenocarcinoma,etc.In this study,a high-throughput screening based on enzyme activity was used to screen lead compounds and candidate drugs targeting PHGDH from natural products of different origins,and their activity was further determined at cellular and animal levels.The screening and activity evaluation system for natural small molecule inhibitors targeting at PHGDH was established.Azacoccone E,an aza-epicoccone derivative from the culture of Aspergillus flavipes,exhibited effective inhibitory activity against PHGDH in vitro.The microscale thermophoresis(MST)method and the cellular thermal shift assay(CETSA)confirmed that azacoccone E directly bound to PHGDH.And the cell-based experiments showed that this compound was selectively toxic to PHGDH-dependent cancer cells and could cause apoptosis.Further biochemical assays revealed that it was a noncompetitive inhibitor with respect to the substrate of 3-PG and exhibited a time-dependent inhibition.Furthermore,molecular docking demonstrated that azacoccone E coordinated in an allosteric site of PHGDH with low binding energy.Therefore,azacoccone E can be developed as a potential inhibitor of PHGDH for treatment of cancers.Inspired by the homology of medicine and food,the in vitro enzymatic activity of Ixocarpalactone A(IoxA)from dietary tomatillo was shown to be a potent PHGDH non-competitive inhibitor,and molecular docking predicted that IoxA bound to the allosteric site of the enzyme.The MST assay,drug affinity response target protein stability(DARTS)assay and siRNA knockdown PHGDH assay were applied to demonstrate that IoxA inhibited pancreatic cancer cell growth by targeting PHGDH.Further in vivo experiments demonstrated that the compounds exhibited potent inhibition of tumor cell growth in mice at dose of 50 mg/kg and 100 mg/kg.Thus,IoxA is a kind of effective natural small molecule inhibitor of PHGDH,which has great development and research value and is considered as a potential candidate for targeting PHGDH in the treatment of cancer.