scholarly journals GOLPH3 Regulates EGFR in T98G Glioblastoma Cells by Modulating Its Glycosylation and Ubiquitylation

2020 ◽  
Vol 21 (22) ◽  
pp. 8880
Author(s):  
Cecilia Arriagada ◽  
Viviana A. Cavieres ◽  
Charlotte Luchsinger ◽  
Alexis E. González ◽  
Vanessa C. Muñoz ◽  
...  
Keyword(s):  
Protein Trafficking ◽  
Growth Factor Receptor ◽  
Primary Brain Tumor ◽  
Normal Cells ◽  
Subcellular Compartment ◽  
Peripheral Membrane Protein ◽  
Tumor Phenotype ◽  
Epidermal Growth ◽  
Golgi Network ◽  
Tumor Types

Protein trafficking is altered when normal cells acquire a tumor phenotype. A key subcellular compartment in regulating protein trafficking is the Golgi apparatus, but its role in carcinogenesis is still not well defined. Golgi phosphoprotein 3 (GOLPH3), a peripheral membrane protein mostly localized at the trans-Golgi network, is overexpressed in several tumor types including glioblastoma multiforme (GBM), the most lethal primary brain tumor. Moreover, GOLPH3 is currently considered an oncoprotein, however its precise function in GBM is not fully understood. Here, we analyzed in T98G cells of GBM, which express high levels of epidermal growth factor receptor (EGFR), the effect of stable RNAi-mediated knockdown of GOLPH3. We found that silencing GOLPH3 caused a significant reduction in the proliferation of T98G cells and an unexpected increase in total EGFR levels, even at the cell surface, which was however less prone to ligand-induced autophosphorylation. Furthermore, silencing GOLPH3 decreased EGFR sialylation and fucosylation, which correlated with delayed ligand-induced EGFR downregulation and its accumulation at endo-lysosomal compartments. Finally, we found that EGF failed at promoting EGFR ubiquitylation when the levels of GOLPH3 were reduced. Altogether, our results show that GOLPH3 in T98G cells regulates the endocytic trafficking and activation of EGFR likely by affecting its extent of glycosylation and ubiquitylation.

scholarly journals A Role for Sorting Nexin 2 in Epidermal Growth Factor Receptor Down-regulation: Evidence for Distinct Functions of Sorting Nexin 1 and 2 in Protein Trafficking

2004 ◽  
Vol 15 (5) ◽  
pp. 2143-2155 ◽  
Author(s):  
Anuradha Gullapalli ◽  
Tiana A. Garrett ◽  
May M. Paing ◽  
Courtney T. Griffin ◽  
Yonghua Yang ◽  
...  
Keyword(s):  
Epidermal Growth Factor Receptor ◽  
Growth Factor ◽  
Epidermal Growth Factor ◽  
Protein Trafficking ◽  
Growth Factor Receptor ◽  
Down Regulation ◽  
Sorting Nexin ◽  
Px Domain ◽  
Early Endosomes ◽  
Epidermal Growth

Sorting nexin 1 (SNX1) and SNX2, homologues of the yeast vacuolar protein-sorting (Vps)5p, contain a phospholipid-binding motif termed the phox homology (PX) domain and a carboxyl terminal coiled-coil region. A role for SNX1 in trafficking of cell surface receptors from endosomes to lysosomes has been proposed; however, the function of SNX2 remains unknown. Toward understanding the function of SNX2, we first examined the distribution of endogenous protein in HeLa cells. We show that SNX2 resides primarily in early endosomes, whereas SNX1 is found partially in early endosomes and in tubulovesicular-like structures distributed throughout the cytoplasm. We also demonstrate that SNX1 interacts with the mammalian retromer complex through its amino terminal domain, whereas SNX2 does not. Moreover, activated endogenous epidermal growth factor receptor (EGFR) colocalizes markedly with SNX2-positive endosomes, but minimally with SNX1-containing vesicles. To assess SNX2 function, we examined the effect of a PX domain-mutated SNX2 that is defective in vesicle localization on EGFR trafficking. Mutant SNX2 markedly inhibited agonist-induced EGFR degradation, whereas internalization remained intact. In contrast, SNX1 PX domain mutants failed to effect EGFR degradation, whereas a SNX1 deletion mutant significantly inhibited receptor down-regulation. Interestingly, knockdown of SNX1 and SNX2 expression by RNA interference failed to alter agonist-induced EGFR down-regulation. Together, these findings suggest that both SNX1 and SNX2 are involved in regulating lysosomal sorting of internalized EGFR, but neither protein is essential for this process. These studies are the first to demonstrate a function for SNX2 in protein trafficking.

scholarly journals Targeted Therapy for Advanced Solid Tumors on the Basis of Molecular Profiles: Results From MyPathway, an Open-Label, Phase IIa Multiple Basket Study

2018 ◽  
Vol 36 (6) ◽  
pp. 536-542 ◽  
Author(s):  
John D. Hainsworth ◽  
Funda Meric-Bernstam ◽  
Charles Swanton ◽  
Herbert Hurwitz ◽  
David R. Spigel ◽  
...  
Keyword(s):  
Epidermal Growth Factor Receptor ◽  
Targeted Therapy ◽  
Growth Factor ◽  
Epidermal Growth Factor ◽  
Objective Response ◽  
Growth Factor Receptor ◽  
Molecular Alterations ◽  
Epidermal Growth ◽  
Tumor Types ◽  
Murine Sarcoma

Purpose Detection of specific molecular alterations in tumors guides the selection of effective targeted treatment of patients with several types of cancer. These molecular alterations may occur in other tumor types for which the efficacy of targeted therapy remains unclear. The MyPathway study evaluates the efficacy and safety of selected targeted therapies in tumor types that harbor relevant genetic alterations but are outside of current labeling for these treatments. Methods MyPathway ( ClinicalTrials.gov identifier: NCT02091141) is a multicenter, nonrandomized, phase IIa multiple basket study. Patients with advanced refractory solid tumors harboring molecular alterations in human epidermal growth factor receptor-2, epidermal growth factor receptor, v-raf murine sarcoma viral oncogene homolog B1, or the Hedgehog pathway are treated with pertuzumab plus trastuzumab, erlotinib, vemurafenib, or vismodegib, respectively. The primary end point is investigator-assessed objective response rate within each tumor-pathway cohort. Results Between April 1, 2014 and November 1, 2016, 251 patients with 35 different tumor types received study treatment. The efficacy population contains 230 treated patients who were evaluated for response or discontinued treatment before evaluation. Fifty-two patients (23%) with 14 different tumor types had objective responses (complete, n = 4; partial, n = 48). Tumor-pathway cohorts with notable objective response rates included human epidermal growth factor receptor-2–amplified/overexpressing colorectal (38% [14 of 37]; 95% CI, 23% to 55%) and v-raf murine sarcoma viral oncogene homolog B1 V600-mutated non–small-cell lung cancer (43% [six of 14]; 95% CI, 18% to 71%). Conclusion The four currently approved targeted therapy regimens in the MyPathway study produced meaningful responses when administered without chemotherapy in several refractory solid tumor types not currently labeled for these agents.

Phase I Safety, Pharmacokinetic, and Pharmacodynamic Trial of ZD1839, a Selective Oral Epidermal Growth Factor Receptor Tyrosine Kinase Inhibitor, in Patients With Five Selected Solid Tumor Types

2002 ◽  
Vol 20 (21) ◽  
pp. 4292-4302 ◽  
Author(s):  
J. Baselga ◽  
D. Rischin ◽  
M. Ranson ◽  
H. Calvert ◽  
E. Raymond ◽  
...  
Keyword(s):  
Epidermal Growth Factor Receptor ◽  
Growth Factor ◽  
Epidermal Growth Factor ◽  
Kinase Inhibitor ◽  
Growth Factor Receptor ◽  
Egfr Signaling ◽  
Epidermal Growth ◽  
Grade 3 ◽  
Tumor Types ◽  
Dose Limiting Toxicity

PURPOSE: To establish the safety and tolerability of ZD1839 (Iressa), a selective epidermal growth factor receptor (EGFR) tyrosine kinase inhibitor, and to explore its pharmacokinetic and pharmacodynamic effects in patients with selected solid tumor types. PATIENTS AND METHODS: This was a phase I dose-escalating trial of oral ZD1839 150 mg/d to a maximum of 1,000 mg/d given once daily for at least 28 days. Patients with either advanced non–small-cell lung, ovarian, head and neck, prostate, or colorectal cancer were recruited. RESULTS: Eighty-eight patients received ZD1839 (150 to 1,000 mg/d). At 1,000 mg/d, five of 12 patients experienced dose-limiting toxicity (grade 3 diarrhea [four patients] and grade 3 somnolence [one patient]). The most frequent drug-related adverse events (AEs) were acne-like rash (64%) and diarrhea (47%), which were generally mild (grade 1/2) and reversible on cessation of treatment. No change in ZD1839 safety profile was observed with prolonged administration. Pharmacokinetic analysis showed steady-state exposure to ZD1839 in 98% of patients by day 7. Nineteen patients had stable disease and received ZD1839 for ≥ 3 months; seven of these patients remained on study drug for ≥ 6 months. Serial skin biopsies taken before treatment and at approximately day 28 revealed changes indicative of inhibition of the EGFR signaling pathway. CONCLUSION: ZD1839 was generally well tolerated, with manageable and reversible AEs at doses up to 600 mg/d and dose-limiting toxicity observed at 1,000 mg/d. ZD1839 treatment resulted in clinically meaningful disease stabilization across a range of tumor types and doses. Pharmacodynamic changes in skin confirmed inhibition of EGFR signaling, which was predicted from the mode of action of ZD1839.

scholarly journals The Sodium/Proton Exchanger NHE8 Regulates Late Endosomal Morphology and Function

2010 ◽  
Vol 21 (20) ◽  
pp. 3540-3551 ◽  
Author(s):  
Scott P. Lawrence ◽  
Nicholas A. Bright ◽  
J. Paul Luzio ◽  
Katherine Bowers
Keyword(s):  
Protein Trafficking ◽  
Protein Sorting ◽  
M Cells ◽  
Sodium Potassium ◽  
Cellular Volume ◽  
Data Points ◽  
Intracellular Organelles ◽  
Epidermal Growth ◽  
And Function ◽  
Golgi Network

The pH and lumenal environment of intracellular organelles is considered essential for protein sorting and trafficking through the cell. We provide the first evidence that a mammalian NHE sodium (potassium)/proton exchanger, NHE8, plays a key role in the control of protein trafficking and endosome morphology. At steady state, the majority of epitope-tagged NHE8 was found in the trans-Golgi network of HeLa M-cells, but a proportion was also localized to multivesicular bodies (MVBs). Depletion of NHE8 in HeLa M-cells with siRNA resulted in the perturbation of MVB protein sorting, as shown by an increase in epidermal growth factor degradation. Additionally, NHE8-depleted cells displayed striking perinuclear clustering of endosomes and lysosomes, and there was a ninefold increase in the cellular volume taken up by LAMP1/LBPA-positive, dense MVBs. Our data points to a role for the ion exchange activity of NHE8 being required to maintain endosome morphology, as overexpression of a nonfunctional point mutant protein (NHE8 E225Q) resulted in phenotypes similar to those seen after siRNA depletion of endogenous NHE8. Interestingly, we found that depletion of NHE8, despite its function as a sodium (potassium)/proton antiporter, did not affect the overall pH inside dense MVBs.

scholarly journals The Kinetics of Mannose 6-Phosphate Receptor Trafficking in the Endocytic Pathway in HEp-2 Cells: The Receptor Enters and Rapidly Leaves Multivesicular Endosomes without Accumulating in a Prelysosomal Compartment

1998 ◽  
Vol 9 (4) ◽  
pp. 809-816 ◽  
Author(s):  
Jennifer Hirst ◽  
Clare E. Futter ◽  
Colin R. Hopkins
Keyword(s):  
Growth Factor ◽  
Epidermal Growth Factor ◽  
Growth Factor Receptor ◽  
Cell Types ◽  
Endocytic Pathway ◽  
Receptor Complexes ◽  
Epidermal Growth ◽  
Mannose 6 Phosphate ◽  
Golgi Network ◽  
Multivesicular Endosomes

We have previously shown that in HEp-2 cells, multivesicular bodies (MVBs) processing internalized epidermal growth factor–epidermal growth factor receptor complexes mature and fuse directly with lysosomes in which the complexes are degraded. The MVBs do not fuse with a prelysosomal compartment enriched in mannose 6-phosphate receptor (M6PR) as has been described in other cell types. Here we show that the cation-independent M6PR does not become enriched in the endocytic pathway en route to the lysosome, but if a pulse of M6PR or an M6PR ligand, cathepsin D, is followed, a significant fraction of these proteins are routed from the trans-Golgi to MVBs. Accumulation of M6PR does not occur because when the ligand dissociates, the receptor rapidly leaves the MVB. At steady state, most M6PR are distributed within the trans-Golgi andtrans-Golgi network and in vacuolar structures distributed in the peripheral cytoplasm. We suggest that these M6PR-rich vacuoles are on the return route from MVBs to thetrans-Golgi network and that a separate stable M6PR-rich compartment equivalent to the late endosome/prelysosome stage does not exist on the endosome–lysosome pathway in these cells.

Quantitative Evaluation of Protein Expression as a Function of Tissue Microarray Core Diameter: Is a Large (1.5 mm) Core Better Than a Small (0.6 mm) Core?

2010 ◽  
Vol 134 (4) ◽  
pp. 613-619
Author(s):  
Valsamo K. Anagnostou ◽  
Frank J. Lowery ◽  
Konstantinos N. Syrigos ◽  
Philip T. Cagle ◽  
David L. Rimm
Keyword(s):  
Growth Factor Receptor ◽  
Tissue Microarrays ◽  
Core Size ◽  
Experimental Conditions ◽  
Core Diameter ◽  
Formalin Fixed Paraffin ◽  
Identical Manner ◽  
Formalin Fixed Paraffin Embedded ◽  
Epidermal Growth ◽  
Tumor Types

Abstract Context.—Tissue microarrays (TMAs) have emerged as a high-throughput technology for protein evaluation in large cohorts. This technique allows maximization of tissue resources by analysis of sections from 0.6-mm to 1.5-mm core “biopsies” of standard formalin-fixed, paraffin-embedded tissue blocks and by the processing of hundreds of cases arrayed on a single recipient block in an identical manner. Objective.—To assess the expression of a series of biomarkers as a function of core size. Although pathologists frequently feel better if larger core sizes are used, there is no evidence in the literature showing that large cores are better (or worse) than small cores for assessment of TMAs. Design.—Estrogen receptor, HER2/neu, epidermal growth factor receptor, STAT3, mTOR, and phospho-p70 S6 kinase were measured by immunofluorescence with automated quantitative analysis. One random 0.6-mm field (one 0.6-mm spot) was compared to 6 to 12 fields per spot, representing 1-mm and 1.5-mm cores, for 3 different tumor types. Results.—We show that measurement of a single random 0.6-mm spot was comparable to analysis of the whole 1-mm or 1.5-mm spot (Pearson R coefficient varying from 0.87–0.98) for all markers tested. Conclusions.—Since TMA technology is now being used in all phases of biomarker development, this work shows that TMAs with 0.6-mm cores are as representative as those with any common larger core size for optimization of standardized experimental conditions. Given that a greater number of 0.6-cores can be arrayed in a single master block, use of this core size allows increased throughput and decreased cost.

scholarly journals Mechanisms of EGFR Resistance in Glioblastoma

2020 ◽  
Vol 21 (22) ◽  
pp. 8471
Author(s):  
Peter C. Pan ◽  
Rajiv S. Magge
Keyword(s):  
Growth Factor Receptor ◽  
Extracellular Domain ◽  
Kinase Domain ◽  
Small Cell ◽  
Small Cell Lung ◽  
History Of ◽  
Epidermal Growth ◽  
Tumor Types ◽  
Primary Malignant Brain Tumor

Glioblastoma (GBM) is the most common primary malignant brain tumor in adults. Despite numerous efforts to target epidermal growth factor receptor (EGFR), commonly dysregulated in GBM, approaches directed against EGFR have not achieved the same degree of success as seen in other tumor types, particularly as compared to non-small cell lung cancer (NSCLC). EGFR alterations in glioblastoma lie primarily in the extracellular domain, unlike the kinase domain alterations seen in NSCLC. Small molecule inhibitors are difficult to develop for the extracellular domain. Monoclonal antibodies can be developed to target the extracellular domain but must contend with the blood brain barrier (BBB). We review the role of EGFR in GBM, the history of trialed treatments, and the potential paths forward to target the pathway that may have greater success.

scholarly journals Potential evolution of neurosurgical treatment paradigms for craniopharyngioma based on genomic and transcriptomic characteristics

2016 ◽  
Vol 41 (6) ◽  
pp. E3 ◽  
Author(s):  
Leslie C. Robinson ◽  
Sandro Santagata ◽  
Todd C. Hankinson
Keyword(s):  
Primary Cilia ◽  
Growth Factor Receptor ◽  
High Morbidity ◽  
Shh Signaling ◽  
Surgical Interventions ◽  
Neurosurgical Treatment ◽  
Epidermal Growth ◽  
Adamantinomatous Craniopharyngioma ◽  
Tumor Types

The recent genomic and transcriptomic characterization of human craniopharyngiomas has provided important insights into the pathogenesis of these tumors and supports that these tumor types are distinct entities. Critically, the insights provided by these data offer the potential for the introduction of novel therapies and surgical treatment paradigms for these tumors, which are associated with high morbidity rates and morbid conditions. Mutations in the CTNNB1 gene are primary drivers of adamantinomatous craniopharyngioma (ACP) and lead to the accumulation of β-catenin protein in a subset of the nuclei within the neoplastic epithelium of these tumors. Dysregulation of epidermal growth factor receptor (EGFR) and of sonic hedgehog (SHH) signaling in ACP suggest that paracrine oncogenic mechanisms may underlie ACP growth and implicate these signaling pathways as potential targets for therapeutic intervention using directed therapies. Recent work shows that ACP cells have primary cilia, further supporting the potential importance of SHH signaling in the pathogenesis of these tumors. While further preclinical data are needed, directed therapies could defer, or replace, the need for radiation therapy and/or allow for less aggressive surgical interventions. Furthermore, the prospect for reliable control of cystic disease without the need for surgery now exists. Studies of papillary craniopharyngioma (PCP) are more clinically advanced than those for ACP. The vast majority of PCPs harbor the BRAFv600e mutation. There are now 2 reports of patients with PCP that had dramatic therapeutic responses to targeted agents. Ongoing clinical and research studies promise to not only advance our understanding of these challenging tumors but to offer new approaches for patient management.

Designing Transformative Clinical Trials in the Cancer Genome Era

2013 ◽  
Vol 31 (15) ◽  
pp. 1834-1841 ◽  
Author(s):  
Stefan Sleijfer ◽  
Jan Bogaerts ◽  
Lillian L. Siu
Keyword(s):  
Clinical Trial ◽  
Clinical Trials ◽  
Point Of Care ◽  
Growth Factor Receptor ◽  
Molecular Profiling ◽  
Cancer Genome ◽  
Histopathologic Diagnosis ◽  
Epidermal Growth ◽  
Clinical Trial Designs ◽  
Tumor Types

The incorporation of molecular profiling into routine clinical practice has already been adopted in some tumor types, such as human epidermal growth factor receptor 2 (HER2) testing in breast cancer and KRAS genotyping in colorectal cancer, providing a guide to treatment selection that is not afforded by histopathologic diagnosis alone. It is inevitable that over time, with rapid advances in scientific knowledge, bioinformatics, and technology to identify oncogenic drivers, molecular profiling will complement histopathologic data to influence management decisions. Emerging technologies such as multiplexed somatic mutation genotyping and massive parallel genomic sequencing have become increasingly feasible at point-of-care locations to classify cancers into molecular subsets. Because these molecular subsets may differ substantially between each other in terms of sensitivity or resistance to systemic agents, there is consensus that clinical trials should be more stratified for or be performed only in such molecularly defined subsets. This approach, however, poses challenges for clinical trial designs because smaller numbers of patients would be eligible for such trials, while the number of novel anticancer drugs warranting further clinical exploration is rapidly increasing. This article provides an overview of the emerging methodologic challenges in the cancer genome era and offers some potential solutions for transforming clinical trial designs so they can identify new active anticancer regimens in molecularly defined subgroups as efficiently as possible.

scholarly journals EGFRvIII: An Oncogene with Ambiguous Role

2019 ◽  
Vol 2019 ◽  
pp. 1-20 ◽  
Author(s):  
Adrianna Rutkowska ◽  
Ewelina Stoczyńska-Fidelus ◽  
Karolina Janik ◽  
Aneta Włodarczyk ◽  
Piotr Rieske
Keyword(s):  
Mechanism Of Action ◽  
Growth Factor Receptor ◽  
Tumor Aggressiveness ◽  
Wild Type ◽  
Primary Tumors ◽  
Membrane Function ◽  
Car T ◽  
Epidermal Growth ◽  
Tumor Types

Epidermal growth factor receptor variant III (EGFRvIII) seems to constitute the perfect therapeutic target for glioblastoma (GB), as it is specifically present on up to 28–30% of GB cells. In case of other tumor types, expression and possible role of this oncogene still remain controversial. In spite of EGFRvIII mechanism of action being crucial for the design of small active anticancer molecules and immunotherapies, i.e., CAR-T technology, it is yet to be precisely defined. EGFRvIII is known to be resistant to degradation, but it is still unclear whether it heterodimerizes with EGF-activated wild-type EGFR (EGFRWT) or homodimerizes (including covalent homodimerization). Constitutive kinase activity of this mutated receptor is relatively low, and some researchers even claim that a nuclear, but not a membrane function, is crucial for its activity. Based on the analyses of recurrent tumors that are often lacking EGFRvIII expression despite its initial presence in corresponding primary foci, this oncogene is suggested to play a marginal role during later stages of carcinogenesis, while even in primary tumors EGFRvIII expression is detected only in a small percentage of tumor cells, undermining the rationality of EGFRvIII-targeting therapies. On the other hand, EGFRvIII-positive cells are resistant to apoptosis, more invasive, and characterized with enhanced proliferation rate. Moreover, expression of this oncogenic receptor was also postulated to be a marker of cancer stem cells. Opinions regarding the role that EGFRvIII plays in tumorigenesis and for tumor aggressiveness are clearly contradictory and, therefore, it is crucial not only to determine its mechanism of action, but also to unambiguously define its role at early and advanced cancer stages.

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