Distinct molecular targets of ProEGCG from EGCG and superior inhibition of angiogenesis signaling pathways for treatment of endometriosis

Endometriosis is a common chronic gynecological disease with endometrial cell implantation outside the uterus. Angiogenesis is a major pathophysiology in endometriosis. Our previous studies have demonstrated that the prodrug of epigallocatechin gallate (ProEGCG) exhibits superior anti-endometriotic and anti-angiogenic effects compared to epigallocatechin gallate (EGCG). However, their direct binding targets and underlying mechanisms for the differential effects remain unknown. In this study, we demonstrated that oral ProEGCG can be effective in preventing and treating endometriosis. Additionally, 1D and 2D Proteome Integral Solubility Alteration assay-based chemical proteomics identified metadherin (MTDH) and PX domain containing serine/threonine kinase-like (PXK) as novel binding targets of EGCG and ProEGCG, respectively. Computational simulation and BioLayer interferometry were used to confirm their binding affinity. Our results showed that MTDH-EGCG inhibited protein kinase B (Akt)-mediated angiogenesis, while PXK-ProEGCG inhibited epidermal growth factor (EGF)-mediated angiogenesis via the EGF/hypoxia-inducible factor (HIF-1a)/vascular endothelial growth factor (VEGF) pathway. In vitro and in vivo knockdown assays and microvascular network imaging further confirmed the involvement of these signaling pathways. Moreover, our study demonstrated that ProEGCG has superior therapeutic effects than EGCG by targeting distinct signal transduction pathways and may act as a novel antiangiogenic therapy for endometriosis.