Nanoconjugation prolongs endosomal signaling of the epidermal growth factor receptor and enhances apoptosis

Abstract

It is becoming increasingly clear that intracellular signaling can be subject to strict spatial control. As the covalent attachment of a signaling ligand to a nanoparticle (NP) impacts ligand-receptor binding, uptake, and trafficking, nanoconjugation provides new opportunities for manipulating intracellular signaling in a controlled fashion. To establish the effect of nanoconjugation on epidermal growth factor (EGF) mediated signaling, we investigate here the intracellular fate of nanoconjugated EGF (NP-EGF) and its bound receptor (EGFR) by quantitative correlated darkfield/fluorescence microscopy and density-based endosomal fractionation. We demonstrate that nanoconjugation prolongs the dwell time of phosphorylated receptors in the early endosomes and that the retention of activated EGFR in the early endosomes is accompanied by an EGF mediated apoptosis at effective concentrations that do not induce apoptosis in the case of free EGF. Overall, these findings indicate nanoconjugation as a rational strategy for modifying signaling that acts by modulating the temporo-spatial distribution of the activated EGF-EGFR ligand-receptor complex.

Nanoparticle–cell interactions induced apoptosis: a case study with nanoconjugated epidermal growth factor

“…Previous studies have shown that EGF nanoconjugation triggers apoptosis in different cancer cell lines (A431, MDA-MB-468, HeLa). 25–26 In this study, we focus on the EGFR-overexpressing MDA-MB-468 breast cancer cell line, which is an established model system for investigating the apoptotic efficacy of free EGF. 14 We chose a relatively short incubation time of NP-EGF with cells of 4 h in our studies to provide a stringent test of the efficacy of NP-EGF with different NP core diameters and shapes and to minimize detrimental effects of long colloidal NP incubation times (agglomeration, NP settlement, non-specific binding, etc.).…”

“…25 The gain in apoptotic efficacy due to nanoconjugation of EGF was confirmed in both EGFR overexpressors (A431, MDA-MB-468) as well as in cells with physiological EGFR expression levels (HeLa). 25–26 The mechanism by which nanoconjugation of EGF “switches” the signaling outcome from proliferation to apoptosis and how the effect depends on the physico-chemical properties of the NP core remain, however, unclear. As an important first step towards an improved understanding of the underlying NP-cell interactions that modulate EGF signaling, we characterize in this work the dependence of NP-EGF induced apoptosis on the intrinsic NP parameters size, shape, and EGF surface loading and elucidate the role of NP-EGF induced oxidative stress in inducing apoptosis.…”

EGF receptor lysosomal degradation is delayed in the cells stimulated with EGF-Quantum dot bioconjugate but earlier key events of endocytic degradative pathway are similar to that of native EGF

“…According to the manufacturer's statement savQD is about 15–20 nm in diameter [ 50 ]. Importantly, in the recent paper of [ 51 ] it was shown that EGF-complexed nanoparticles resulted in a sufficient delay of endosome maturation and consequent increase in the caspase activity. Basing on the above-mentioned, the authors suggest nanoparticle involvement in the apoptosis stimulation.…”

<p>Epidermal Growth Factor Receptor and Its Role in Pancreatic Cancer Treatment Mediated by Nanoparticles</p>

“…Inhibition of endocytosis will also reduce the efficiency of signaling by MAPK and PI3K 74. Based on this premise, the administration of EGF-functionalized gold nanoparticles on MDA-MB-468 cultures was attempted; the conjugated nanoparticles were retained in early endosomes for a longer time at much lower EGF concentrations compared to free EGF needed to induce apoptosis 75…”