131. EGFR and the mitochondria; two parallel pathways regulating sFLT-1 secretion from placenta

Abstract

Introduction Although discovered more than a decade ago, the molecular pathways regulating sFLT-1 release in preeclampsia are still poorly understood. We have discovered the EGFR superhighway and the mitochondria (either via inhibiting the electron transport chain (ETC) or increasing molecules associated with mitochondrial biogenesis) independently regulate sFLT-1 secretion from placenta. The aim of this study was to assess whether targeting both pathways simultaneously additively reduced sFLT-1. Methods Isolated primary trophoblast were used for all studies. Metformin is a mitochondrial ETC inhibitor and resveratrol stimulates expression of mitochondrial biogenesis molecules SIRT1, AMPK and PGC1a. We initially assessed their effects on EGFR expression and activation using western blot. Gefitinib is an EGFR inhibitor, PD98059 a MEK-1 inhibitor and AG490 a STAT3 inhibitor (pathways downstream of the EGFR). We assessed their effects on mitochondrial respiration using a seahorse flux analyser. Having identified molecules that were either “EGFR-specific” or “Mitochondrial specific” we subsequently treated primary trophoblast simultaneously with drugs targeting both pathways and measured the effect on sFLT-1 secretion. Results Treatment of primary trophoblast with metformin or resveratrol significantly reduced sFLT-1 secretion and increased down-stream mitochondrial biogenesis molecules but had no significant effect on EGFR, pEGFR or downstream adaptor molecules ERK, pERK, STAT-3 or pSTAT-3. Although inhibitors targeting the EGFR super-highway also significantly reduced sFLT-1 secretion, none significantly altered mitochondrial respiration, or ATP production. When we targeted the two pathways simultaneously (combining gefitinib and metformin, gefitinib and resveratrol, metformin and PD980 or metformin and AG490) we found the reduction in sFLT-1 was additive compared to targeting either pathway alone. Conclusions Our study identifies EGFR signalling and the mitochondria as two parallel pathways that both regulate sFLT-1 secretion and which, when targeted simultaneously, can additively reduce sFLT-1. These pathways provide new therapeutic targets to reduce excess sFLT-1 secretion in pathological conditions and improve vascular homeostasis.