Adaptor protein APPL1 interacts with EGFR to orchestrate EGF-stimulated signaling

Spatiotemporal regulation of the hepatocyte growth factor receptor MET activity by sorting nexins 1/2 in HCT116 colorectal cancer cells

Cumulative research findings support the idea that endocytic trafficking is crucial in regulating receptor signaling and associated diseases. Specifically, strong evidence points to the involvement of sorting nexins (SNXs), particularly SNX1 and SNX2, in the signaling and trafficking of the receptor tyrosine kinase (RTK) MET in colorectal cancer (CRC). Activation of hepatocyte growth factor (HGF) receptor MET is a key driver of CRC progression. In the present study, we utilized human HCT116 CRC cells with SNX1 and SNX2 genes knocked out to demonstrate that their absence leads to a delay in MET entering early endosomes. This delay results in increased phosphorylation of both MET and AKT upon HGF stimulation, while ERK1/2 (extracellular signal-regulated kinases 1 and 2) phosphorylation remains unaffected. Despite these changes, HGF-induced cell proliferation, scattering, and migration remain similar between the parental and the SNX1/2 knockout cells. However, in the absence of SNX1 and SNX2, these cells exhibit increased resistance to TRAIL-induced apoptosis. This research underscores the intricate relationship between intracellular trafficking, receptor signaling, and cellular responses and demonstrates for the first time that the modulation of MET trafficking by SNX1 and SNX2 is critical for receptor signaling that may exacerbate the disease.

EGF-expressed human mesenchymal stem cells inhibit collagenase1 expression in keratinocytes

Mesenchymal stem cells (MSCs) repair tissue injury by upregulating the paracrine secretion of cytokines and growth factors. Human MSC has been recognized as a promising therapeutic material for treatment of various human diseases. Even though the effect of epidermal growth factor (EGF) has been well investigated, the synergetic effect of EGF and MSC has not been studied. Therefore, we expect our basic study to contribute to developing new therapeutic reagents for skin diseases or innovative cosmetics. In this study, we examined the effect of human epidermal growth factor-transfected MSCs (hEGF MSCs) on human keratinocyte HaCaT cell proliferation and the mechanisms that regulate matrix metalloproteinase (MMP)-1 expression in HaCaT cells. To identify the hEGF plasmid and its transfection into MSCs, we performed gel electrophoresis and quantitative PCR. Proliferation and migration of HaCaT cells were examined using water Soluble Tetrazolium (WST-1) and wound-healing assays, respectively. Zymography was performed to investigate the correlation between hEGF MSC-conditioned medium (CM)-treated HaCaT cells and MMP-1 expression. We found that cell proliferation and wound-healing rates were increased in hEGF MSC-CM-treated HaCaT cells compared to those in MSC-CM-treated cells, and conversely collagenase activity was decreased. The mRNA and protein levels of MMP-1 were also decreased in hEGF MSC-CM-treated HaCaT cells. 2-DE analysis showed that the expression of carboxypeptidase, which promotes growth factors and wound healing, was increased in hEGF MSC-CM-treated HaCaT cells. Finally, western blot was used to determine whether MMP-1 expression was reduced via the mitogen-activated protein kinase (MAPK) pathway; the results showed that the levels of MAPK pathway-related proteins (pErk, pJNK, and p-p38) and the levels of transcription factors (pCREB, NFκB, and p-c-Fos) were decreased. In addition, pAkt expression was found to be elevated. The results of our study suggest that hEGF MSCs promote cell proliferation and reduce MMP-1 expression via the MAPK pathway in human keratinocyte HaCaT cells.

Ionic Liquid-Based Extraction System for In-Depth Analysis of Membrane Protein Complexes

Limited by the rare efficient extraction system in extracting hydrophobic membrane protein complexes (MPCs) without compromising the stability of protein-protein interactions (PPIs), the in-depth functional study of MPCs has lagged far behind. In this study, the first systematic screening of ionic liquids (ILs) was performed and showed that triethylammonium acetate (TEAA) IL exhibited excellent performance in stabilizing PPIs, which was further confirmed by molecular docking simulations. By combining TEAA with the conventional detergent Nonidet P-40 (NP-40), a novel IL-based extraction system, i-TAN (TEAA IL with 1% NP-40), was proposed, which demonstrated superior performance in extracting and stabilizing MPCs, attributed to its larger size, more uniform distribution, and closer-to-neutral microenvironment of micelles. Extraction of MPCs with i-TAN allowed the confident identification of more hydrophobic EGFR-interacting proteins that are easily dissociated during the extraction process. Quantitative analysis of the difference in EGFR complexes between trastuzumab-sensitive and trastuzumab-resistant breast cancer cells provided comprehensive insights to understand the drug resistance mechanism, suggesting that i-TAN has great potential in interactomics and functional analysis of MPCs. This study provides a novel strategy for MPC extraction and downstream processing.

Intracellular proteome compartmentalization: a biotin ligase-based proximity labeling approach

Specialized biological processes occur in different regions and organelles of the cell. Additionally, the function of proteins correlate greatly with their interactions and subcellular localization. Understanding the mechanism underlying the specialized functions of cellular structures therefore requires a detailed identification of proteins within spatially defined domains of the cell. Furthermore, the identification of interacting proteins is also crucial for the elucidation of the underlying mechanism of complex cellular processes. Mass spectrometry methods have been utilized systematically for the characterization of the proteome of isolated organelles and protein interactors purified through affinity pull-down or following crosslinking. However, the available methods of purification have limited these approaches, as it is difficult to derive intact organelles of high purity in many circumstances. Furthermore, contamination that leads to the identification of false positive is widespread even when purification is possible. Here, we present a highlight of the BioID proximity labeling approach which has been used to effectively characterize the proteomic composition of several cellular compartments. In addition, an observed limitation of this method based on proteomic spatiotemporal dynamics, was also discussed.

Novel quinazoline-based EGFR kinase inhibitors: A review focussing on SAR and molecular docking studies (2015-2019)

The over expression of EGFR has been recognized as the driver mechanism in the occurrence and progression of carcinomas such as lung cancer, breast cancer, pancreatic cancer, etcetera. EGFR receptor was thus established as an important target for the management of solid tumors. The occurrence of resistance caused as a result of mutations in EGFR has presented a formidable challenge in the discovery of novel inhibitors of EGFR. This has resulted in the development of three generations of EGFR TKIs. Newer mutations like C797S cause failure of Osimertinib and other EGFR TKIs belonging to the third-generation caused by the development of resistance. In this review, we have summarized the work done in the last five years to overcome the limitations of currently marketed drugs, giving structural activity relationships of quinazoline-based lead compounds synthesized and tested recently. We have also highlighted the shortcomings of the currently used approaches and have provided guidance for circumventing these limitations. Our review would help medicinal chemists streamline and guide their efforts towards developing novel quinazoline-based EGFR inhibitors.

Targeted peptide-Au cluster binds to epidermal growth factor receptor (EGFR) in both active and inactive states: a clue for cancer inhibition through dual pathways

The epidermal growth factor receptor (EGFR) has become an important target protein in anticancer drug development. Meanwhile, peptide-Au cluster has been proposed as potential targeted nano-drug assembled by targeting peptide. Here, we designed and synthesized a novel peptide-Au cluster as Au₁₀Peptide₅ to target to EGFR. We found Au₁₀Peptide₅ could target to the natural binding sites of all EGFRs at membrane in both active and inactive states by molecular simulations. Its targeted ability was further verified by the co-localization and blocking experiments. We also study the configuration modifications of both active and inactive EGFRs after binding by Au₁₀Peptide₅. For active EGFR, the absorbed Au₁₀Peptide₅ might replace the natural ligand in EGFR endocytosis process. Then, the peptide-Au cluster in endochylema could inhibit the cancer relating enzyme activity including thioredoxin reductase1 (TrxR1) and induce the oxidative stress mediated apoptosis in tumor cells. For inactive EGFR, it was retained in inactive state by Au₁₀Peptide₅ binding to inhibit dimerization of EGFR for anticancer. Both pathways might be applied in anticancer drug development based on the theoretical and experimental study here.