Spatio-temporal regulation of EGFR signaling by the Eps15 homology domain-containing protein 3 (EHD3)

EHD3 promotes gastric cancer progression via Wnt/β-catenin/EMT pathway and associates with clinical prognosis and immune infiltration

Gastric cancer (GC) shows high levels of heterogeneity and predicts a poor prognosis. The expressions of EHD3 are found to be misregulated in a number of tumors. However, the clinical significance and potential function of EHD3 expression in GC patients remain unknown. In this study, we found that EHD3 expression was distinctly increased in GC specimens and cell lines in both TCGA datasets and our cohort. High levels of EHD3 expression were linked to worse outcomes for patients with GC in clinical tests. Nomogram based on multivariate assays displayed good predictive accuracy for GC patients, as evidenced by C-indices and calibration graphs. Low levels of EHD3 mRNA were discovered in GC tissues due to EHD3 methylation's negative regulation of EHD3. In addition, EHD3 was observed to be related to several immune cells and might play a role in successful immunotherapy. Functionally, it was verified that knockdown of EHD3 remarkably suppressed the proliferation, migration and invasion of GC cells in vitro and in vivo. Results of Western blot confirmed that knockdown of EHD3 suppressed the expressions of β-catenin, MMP-9, and N-cadherin, while promoting the expression of E-cadherin. Overall, this research identified a novel GC-related gene EHD3 which might be a novel prognostic biomarker involved in tumor microenvironment. EHD3 promoted the proliferation and metastasis of GC cells through influencing the Wnt/β-catenin/EMT signaling pathway, suggesting it as a novel treatment target for GC patients.

CT-detected extramural venous invasion-related gene signature for the overall survival prediction in patients with gastric cancer

Background

Computed tomography (CT)‐detected extramural venous invasion (EMVI) has been identified as an independent factor that can be used for risk stratification and prediction of prognosis in patients with gastric cancer (GC). Overall survival (OS) is identified as the most important prognostic indicator for GC patients. However, the molecular mechanism of EMVI development and its potential relationship with OS in GC are not fully understood. In this radiogenomics‐based study, we sought to investigate the molecular mechanism underlying CT‐detected EMVI in patients with GC, and aimed to construct a genomic signature based on EMVI‐related genes with the goal of using this signature to predict the OS.

Materials and Methods

Whole mRNA genome sequencing of frozen tumor samples from 13 locally advanced GC patients was performed to identify EMVI‐related genes. EMVI‐prognostic hub genes were selected based on overlapping EMVI‐related differentially expressed genes and OS‐related genes, using a training cohort of 176 GC patients who were included in The Cancer Genome Atlas database. Another 174 GC patients from this database comprised the external validation cohort. A risk stratification model using a seven‐gene signature was constructed through the use of a least absolute shrinkage and selection operator Cox regression model.

Results

Patients with high risk score showed significantly reduced OS (training cohort, p = 1.143e‐04; validation cohort, p = 2.429e‐02). Risk score was an independent predictor of OS in multivariate Cox regression analyses (training cohort, HR = 2.758; 95% CI: 1.825–4.169; validation cohort, HR = 2.173; 95% CI: 1.347–3.505; p < 0.001 for both). Gene functions/pathways of the seven‐gene signature mainly included cell proliferation, cell adhesion, regulation of metal ion transport, and epithelial to mesenchymal transition.

Conclusions

A CT‐detected EMVI‐related gene model could be used to predict the prognosis in GC patients, potentially providing clinicians with additional information regarding appropriate therapeutic strategy and medical decision‐making.

EHD1 and RUSC2 Control Basal Epidermal Growth Factor Receptor Cell Surface Expression and Recycling

Epidermal growth factor receptor (EGFR) is a prototype receptor tyrosine kinase and an oncoprotein in many solid tumors. Cell surface display of EGFR is essential for cellular responses to its ligands. While postactivation endocytic trafficking of EGFR has been well elucidated, little is known about mechanisms of basal/preactivation surface display of EGFR. Here, we identify a novel role of the endocytic regulator EHD1 and a potential EHD1 partner, RUSC2, in cell surface display of EGFR. EHD1 and RUSC2 colocalize with EGFR in vesicular/tubular structures and at the Golgi compartment. Inducible EHD1 knockdown reduced the cell surface EGFR expression with accumulation at the Golgi compartment, a phenotype rescued by exogenous EHD1. RUSC2 knockdown phenocopied the EHD1 depletion effects. EHD1 or RUSC2 depletion impaired the EGF-induced cell proliferation, demonstrating that the novel, EHD1- and RUSC2-dependent transport of unstimulated EGFR from the Golgi compartment to the cell surface that we describe is functionally important, with implications for physiologic and oncogenic roles of EGFR and targeted cancer therapies.

MAP4K4 controlled integrin β1 activation and c-Met endocytosis are associated with invasive behavior of medulloblastoma cells

Local tissue infiltration of Medulloblastoma (MB) tumor cells precedes metastatic disease but little is still known about intrinsic regulation of migration and invasion in these cells. We found that MAP4K4, a pro-migratory Ser/Thr kinase, is overexpressed in 30% of primary MB tumors and that increased expression is particularly associated with the frequently metastatic SHH β subtype. MAP4K4 is a driver of migration and invasion downstream of c-Met, which is transcriptionally up-regulated in SHH MB. Consistently, depletion of MAP4K4 in MB tumor cells restricts HGF-driven matrix invasion in vitro and brain tissue infiltration ex vivo. We show that these pro-migratory functions of MAP4K4 involve the activation of the integrin β-1 adhesion receptor and are associated with increased endocytic uptake. The consequent enhanced recycling of c-Met caused by MAP4K4 results in the accumulation of activated c-Met in cytosolic vesicles, which is required for sustained signaling and downstream pathway activation. The parallel increase of c-Met and MAP4K4 expression in SHH MB could predict an increased potential of these tumors to infiltrate brain tissue and cause metastatic disease. Molecular targeting of the underlying accelerated endocytosis and receptor recycling could represent a novel approach to block pro-migratory effector functions of MAP4K4 in metastatic cancers.

Glucocorticoids, genes and brain function

The identification of key genes in transcriptomic data constitutes a huge challenge. Our review of microarray reports revealed 88 genes whose transcription is consistently regulated by glucocorticoids (GCs), such as cortisol, corticosterone and dexamethasone, in the brain. Replicable transcriptomic data were combined with biochemical and physiological data to create an integrated view of the effects induced by GCs. The most frequently reported genes were Errfi1 and Ddit4. Their up-regulation was associated with the altered transcription of genes regulating growth factor and mTORC1 signaling (Gab1, Tsc22d3, Dusp1, Ndrg2, Ppp5c and Sesn1) and progression of the cell cycle (Ccnd1, Cdkn1a and Cables1). The GC-induced reprogramming of cell function involves changes in the mRNA level of genes responsible for the regulation of transcription (Klf9, Bcl6, Klf15, Tle3, Cxxc5, Litaf, Tle4, Jun, Sox4, Sox2, Sox9, Irf1, Sall2, Nfkbia and Id1) and the selective degradation of mRNA (Tob2). Other genes are involved in the regulation of metabolism (Gpd1, Aldoc and Pdk4), actin cytoskeleton (Myh2, Nedd9, Mical2, Rhou, Arl4d, Osbpl3, Arhgef3, Sdc4, Rdx, Wipf3, Chst1 and Hepacam), autophagy (Eva1a and Plekhf1), vesicular transport (Rhob, Ehd3, Vps37b and Scamp2), gap junctions (Gjb6), immune response (Tiparp, Mertk, Lyve1 and Il6r), signaling mediated by thyroid hormones (Thra and Sult1a1), calcium (Calm2), adrenaline/noradrenaline (Adcy9 and Adra1d), neuropeptide Y (Npy1r) and histamine (Hdc). GCs also affected genes involved in the synthesis of polyamines (Azin1) and taurine (Cdo1). The actions of GCs are restrained by feedback mechanisms depending on the transcription of Sgk1, Fkbp5 and Nr3c1. A side effect induced by GCs is increased production of reactive oxygen species. Available data show that the brain's response to GCs is part of an emergency mode characterized by inactivation of non-core activities, restrained inflammation, restriction of investments (growth), improved efficiency of energy production and the removal of unnecessary or malfunctioning cellular components to conserve energy and maintain nutrient supply during the stress response.