Membrane therapy using DHA suppresses epidermal growth factor receptor signaling by disrupting nanocluster formation

Abstract

Epidermal growth factor receptor (EGFR) signaling drives the formation of many types of cancer, including colon cancer. Docosahexaenoic acid (DHA, 22∶6 Δ4,7,10,13,16,19 ), a chemoprotective long-chain n-3 polyunsaturated fatty acid suppresses EGFR signaling. However, the mechanism underlying this phenotype remains unclear. Therefore, we used super-resolution microscopy techniques to investigate the mechanistic link between EGFR function and DHA-induced alterations to plasma membrane nanodomains. Using isogenic in vitro (YAMC and IMCE mouse colonic cell lines) and in vivo ( Drosophila , wild type and Fat-1 mice) models, cellular DHA enrichment via therapeutic nanoparticle delivery, endogenous synthesis, or dietary supplementation reduced EGFR-mediated cell proliferation and downstream Ras/ERK signaling. Phospholipid incorporation of DHA reduced membrane rigidity and the size of EGFR nanoclusters. Similarly, pharmacological reduction of plasma membrane phosphatidic acid (PA), phosphatidylinositol-4,5-bisphosphate (PIP 2 ) or cholesterol was associated with a decrease in EGFR nanocluster size. Furthermore, in DHA-treated cells only the addition of cholesterol, unlike PA or PIP 2 , restored EGFR nanoscale clustering. These findings reveal that DHA reduces EGFR signaling in part by reshaping EGFR proteolipid nanodomains, supporting the feasibility of using membrane therapy, i.e., dietary/drug-related strategies to target plasma membrane organization, to reduce EGFR signaling and cancer risk.

Biosynthesis and Significance of Fatty Acids, Glycerophospholipids, and Triacylglycerol in the Processes of Glioblastoma Tumorigenesis

“…At higher concentrations of several tens of micromoles, DHA C22:6n-3 is incorporated and builds glycerophospholipids, which are then part of the lipid rafts [ 83 ]. At high concentrations, DHA C22:6n-3 reduces membrane rigidity [ 84 ] and disturbs the structure of lipid rafts, causing the internalization of EGFR along with lipid rafts and their degradation in lysosomal pathways [ 85 , 86 ]. This results in a decrease in the amount of EGFR in the cell membrane [ 87 ].…”

“…This results in a decrease in the amount of EGFR in the cell membrane [ 87 ]. Moreover, DHA C22:6n-3 at high concentrations decreases the amounts of sphingomyelin and cholesterol in lipid rafts [ 83 ] and hinders EGFR clustering by disrupting cholesterol-EGFR interactions [ 84 ]. Since lipid rafts and the interaction of lipids with EGFR are necessary for signal transduction from this receptor, the activity of EGFR is reduced [ 84 , 87 ].…”

“…Moreover, DHA C22:6n-3 at high concentrations decreases the amounts of sphingomyelin and cholesterol in lipid rafts [ 83 ] and hinders EGFR clustering by disrupting cholesterol-EGFR interactions [ 84 ]. Since lipid rafts and the interaction of lipids with EGFR are necessary for signal transduction from this receptor, the activity of EGFR is reduced [ 84 , 87 ]. As a result of DHA C22:6n-3’s actions at high concentrations, processes dependent on this receptor are blocked, resulting in the inhibition of wound healing [ 88 ].…”

Dysregulation of cellular membrane homeostasis as a crucial modulator of cancer risk

“…This makes it ideal for conventional microscopy imaging, such as confocal microscopy [278], total internal reflection microscopy [281] and flow cytometry [282]. Notably, Di-4 has been successfully utilized to investigate a variety of membrane order-chronic diseases [280,[283][284][285][286]. Recently, a new series of salvatochromic fluorophores for lipid order measurements have been developed, including Laurdan-modified probe Pro12A [287] and Nile Red-based probes, for example NR12S, NR12A and NR Mito [288,289].…”

“…With the development of machine learning/ deep learning algorithms, data analyses are typically faster and more robust. Notably, our group has successfully employed IFC to measure membrane rigidity in dissociated single cells and GPMVs using Di-4 [285,286,294]. Undoubtedly, due to the great interest and applicability of these technologies, there will be additional fluorophores utilized for IFC in the future.…”