Structural mechanism of human oncochannel TRPV6 inhibition by the natural phytoestrogen genistein

Calcium-selective oncochannel TRPV6 is the major driver of cell proliferation in human cancers. While significant effort has been invested in the development of synthetic TRPV6 inhibitors, natural channel blockers have been largely neglected. Here we report the structure of human TRPV6 in complex with the plant-derived phytoestrogen genistein, extracted from Styphnolobium japonicum, that was shown to inhibit cell invasion and metastasis in cancer clinical trials. Despite the pharmacological value, the molecular mechanism of TRPV6 inhibition by genistein has remained enigmatic. We use cryo-EM combined with electrophysiology, calcium imaging, mutagenesis, and molecular dynamics simulations to show that genistein binds in the intracellular half of the TRPV6 pore and acts as an ion channel blocker and gating modifier. Genistein binding to the open channel causes pore closure and a two-fold symmetrical conformational rearrangement in the S4-S5 and S6-TRP helix regions. The unprecedented mechanism of TRPV6 inhibition by genistein uncovers new possibilities in structure-based drug design. The authors report the structure of human oncochannel TRPV6 in complex with the plant derived phytoestrogen genistein. The structure provides insights into genistein binding in the channel pore, and how it acts as blocker and gating modifier, suggesting a mechanism of inhibition that can be explored for the structure-based drug design.

Automated summary

The structure of human oncochannel TRPV6 in complex with the plant derived phytoestrogen genistein is reported. Genistein acts as an ion channel blocker and gating modifier, causing pore closure and conformational rearrangement. This new mechanism of TRPV6 inhibition by genistein provides possibilities in structure-based drug design.