Hypoxia-tolerant apical-out intestinal organoids to model host-microbiome interactions.

Microbiome is an integral part of the gut and is essential for its proper function. Imbalances of the microbiota can be devastating and have been linked with several gastrointestinal conditions. Current gastrointestinal models do not fully reflect the in vivo situation.

EGFRvIII expression triggers a metabolic dependency and therapeutic vulnerability sensitive to autophagy inhibition.

Expression of EGFRvIII is frequently observed in glioblastoma and is associated with increased cellular proliferation, enhanced tolerance to metabolic stresses, accelerated tumor growth, therapy resistance and poor prognosis. We observed that expression of EGFRvIII elevates the activation of macroautophagy/autophagy during starvation and hypoxia and explored the underlying mechanism and consequence. Autophagy was inhibited (genetically or pharmacologically) and its consequence for tolerance to metabolic stress and its therapeutic potential in (EGFRvIII) glioblastoma was assessed in cellular systems, (patient derived) tumor xenopgrafts and glioblastoma patients.

A phase I-II study on the combination of rapamycin and short course radiotherapy in rectal cancer.

Purpose: This phase I/II study sought to determine the safety and maximum tolerated dose (MTD) of the combination of rapamycin, an mTOR inhibitor, with short-course radiotherapy in rectal cancer patients. Antitumor activity, changes in metabolic activity and perfusion on imaging, and changes in phosphorylation status of the mTOR pathway were also assessed.

Materials And Methods: Patients with primary resectable rectal cancer were treated with short-course hypofractionated radiotherapy (5×5 Gy) combined with oral rapamycin 1 week before and during radiotherapy, followed by surgical resection.

GABARAPL1 is required for increased EGFR membrane expression during hypoxia.

Background And Purpose: The epidermal growth factor receptor (EGFR) is overexpressed, amplified or mutated in various human epithelial tumors and hypoxia is a common feature of solid tumors. Both EGFR and hypoxia are associated with therapy resistance and poor treatment outcome. To survive hypoxia, cells adapt by activation of hypoxia responsive pathways and expression of hypoxia-induced plasma membrane proteins.

Canonical autophagy does not contribute to cellular radioresistance.

Background: (Pre)clinical studies indicate that autophagy inhibition increases response to anti-cancer therapies. Although promising, due to contradicting reports, it remains unclear if radiation therapy changes autophagy activity and if autophagy inhibition changes the cellular intrinsic radiosensitivity. Discrepancies may result from different assays and models through off-target effects and influencing other signaling routes.

EGFR signaling and autophagy dependence for growth, survival, and therapy resistance.

The epidermal growth factor receptor (EGFR) is amplified or mutated in various human epithelial tumors. Its expression and activation leads to cell proliferation, differentiation, and survival. Consistently, EGFR amplification or expression of EGFR variant 3 (EGFRvIII) is associated with resistance to conventional cancer therapy through activation of pro-survival signaling and DNA-repair mechanisms.

EGFR overexpressing cells and tumors are dependent on autophagy for growth and survival.

Background And Purpose: The epidermal growth factor receptor (EGFR) is overexpressed, amplified or mutated in various human epithelial tumors, and is associated with tumor aggressiveness and therapy resistance. Autophagy activation provides a survival advantage for cells in the tumor microenvironment. In the current study, we assessed the potential of autophagy inhibition (using chloroquine (CQ)) in treatment of EGFR expressing tumors.

The autophagy associated gene, ULK1, promotes tolerance to chronic and acute hypoxia.

Background And Purpose: Tumor hypoxia is associated with therapy resistance and malignancy. Previously we demonstrated that activation of autophagy and the unfolded protein response (UPR) promote hypoxia tolerance. Here we explored the importance of ULK1 in hypoxia tolerance, autophagy induction and its prognostic value for recurrence after treatment.

Translational control is a major contributor to hypoxia induced gene expression.

Background And Purpose: Hypoxia is a common feature of solid tumors that is associated with an aggressive phenotype, resistance to therapy and poor prognosis. Major contributors to these adverse effects are the transcriptional program activated by the HIF family of transcription factors as well as the translational response mediated by PERK-dependent phosphorylation of eIF2α and inhibition of mTORC1 activity. In this study we determined the relative contribution of both transcriptional and translational responses to changes in hypoxia induced gene expression.

E-Cadherin loss associated with EMT promotes radioresistance in human tumor cells.

Background And Purpose: Hypoxia is a hallmark of solid cancers and associated with metastases and treatment failure. During tumor progression epithelial cells often acquire mesenchymal features, a phenomenon known as epithelial-to-mesenchymal transition (EMT). Intratumoral hypoxia has been linked to EMT induction.

Binding of cetuximab to the EGFRvIII deletion mutant and its biological consequences in malignant glioma cells.

Background And Purpose: Despite the clinical use of cetuximab, a chimeric antibody against EGFR, little is known regarding its interaction with EGFRvIII, a frequently expressed deletion mutant of EGFR. Therefore, we investigated the interaction and the functional consequences of cetuximab treatment on glioma cells stably expressing EGFRvIII.

Materials And Methods: The human glioma cell line U373 genetically modified to express EGFRvIII was used to measure the binding of cetuximab and its internalization using flow cytometry and confocal microscopy.

The deletion mutant EGFRvIII significantly contributes to stress resistance typical for the tumour microenvironment.

Background And Purpose: The epidermal growth factor receptor (EGFR) is overexpressed or mutated in many tumour types. The truncated, constitutively active EGFRvIII variant has not been detected in normal tissues but is found in many malignancies. In the current study, we have investigated the hypothesis that EGFRvIII contributes to a growth and survival advantage under tumour microenvironment-related stress conditions.

Hypoxia-induced expression of carbonic anhydrase 9 is dependent on the unfolded protein response.

Adaptation to tumor hypoxia is mediated in large part by changes in protein expression. These are driven by multiple pathways, including activation of the hypoxia inducible factor-1 (HIF-1) transcription factor and the PKR-like endoplasmic reticulum kinase PERK, a component of the unfolded protein response. Through gene expression profiling we discovered that induction of the HIF-1 target gene CA9 was defective in mouse embryo fibroblasts derived from mice harboring an eIF2alpha S51A knock-in mutation.

Proteomic analysis of gene expression following hypoxia and reoxygenation reveals proteins involved in the recovery from endoplasmic reticulum and oxidative stress.

Background And Purpose: Human tumors are characterized by large variations in oxygen concentration and hypoxic tumors are associated with poor prognosis. In addition, tumors are subjected to periodic changes in oxygenation characterized by hypoxia followed by reoxygenation. Cellular adaptation to hypoxia is well documented, nevertheless little is known about adaptive mechanisms to reoxygenation.

Development and evaluation of a cetuximab-based imaging probe to target EGFR and EGFRvIII.

Background And Purpose: The epidermal growth factor receptor (EGFR) is overexpressed in a significant percentage of human malignancies and its expression is associated with tumour aggressiveness and treatment resistance. The monoclonal antibody cetuximab (IMC-C225) blocks the ligand-binding domain of EGFR with high affinity, preventing downstream signalling resulting in tumour growth inhibition. We developed and characterized a novel imaging probe using Oregon Green 488 labelled cetuximab to evaluate its usage as an imaging agent to target EGFR.

Expression of EGFR variant vIII promotes both radiation resistance and hypoxia tolerance.

Background And Purpose: EGFRvIII has been described to function as an oncoprotein with constitutive activation promoting neoplastic transformation and tumorigenicity. The present study was undertaken to test whether EGFRvIII also contributes to hypoxia tolerance.

Material And Methods: The human glioma cell line U373 was genetically modified to stably express EGFRvIII.

Vasculin, a novel vascular protein differentially expressed in human atherogenesis.

Recent suppressive subtractive hybridization analysis on human atherosclerotic plaque-derived RNA revealed genes upregulated in plaques with a thrombus versus stable plaques. Clone SSH6, containing part of a putative open reading frame of an unknown protein, was further investigated. Full-length cDNA, coding for a 473-amino acid (aa) protein, was identified in a vascular smooth muscle cell (SMC) cDNA library.