Cure Alveolar Soft Part Sarcoma International (iCureASPS)

“Pitfalls in immunohistochemical assessment of EGFR expression in soft tissue sarcomas“

epidermal growth factor receptor (EGFR)



Abstract

Background

New targeted cancer treatments acting against growth factor receptors such as the epidermal growth factor receptor (EGFR) necessitate selecting patients for treatment with these drugs. Besides carcinomas, soft tissue sarcomas (STS) express EGFR and might thereby be a promising target for this new therapeutic strategy.

Objective

To test and compare different EGFR antibodies to determine the frequency of EGFR expression in STS.

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC1860383/

Associated articles -

https://cureasps.org/forum/viewtopic.ph ... ate#p14787

https://cureasps.org/forum/viewtopic.php?p=15480#p15480

Abstract

Simple Summary

Immunotherapy against PD-1/PD-L1 dramatically improved outcomes in non-small cell lung cancer patients. These treatments are more effective the higher the expression of PD-L1 on tumor cells, reported as tumor proportion score. However, PD-L1 expression can be highly variable, depending on different mechanisms of regulation. These mechanisms are usually grouped in intrisc (including genetic and epigenetic factors) and extrinsic factors (i.e., deriving from interaction of tumor cells with tumor microenvironment or other external factors). We reviewed mechanisms underlying PD-L1 expression regulation in order to provide a comprehensive overview and identify key regulatory factors that are or can potentially be exploited to improve outcomes on immune checkpoint inhibitors targeting the PD-1/PD-L1 axis.

Abstract

Treatment with inhibition of programmed cell death 1 (PD-1) or its ligand (PD-L1) improves survival in advanced non-small-cell lung cancer (NSCLC). Nevertheless, only a subset of patients benefit from treatment and biomarkers of response to immunotherapy are lacking. Expression of PD-L1 on tumor cells is the primary clinically-available predictive factor of response to immune checkpoint inhibitors, and its relevance in cancer immunotherapy has fostered several studies to better characterize the mechanisms that regulate PD-L1 expression. However, the factors associated with PD-L1 expression are still not well understood. Genomic alterations that activate KRAS, EGFR, and ALK, as well as the loss of PTEN, have been associated with increased PD-L1 expression. In addition, PD-L1 expression is reported to be increased by amplification of CD274, and decreased by STK11 deficiency. Furthermore, PD-L1 expression can be modulated by either tumor extrinsic or intrinsic factors. Among extrinsic factors, the most prominent one is interferon-γ release by immune cells, while there are several tumor intrinsic factors such as activation of the mechanistic target of rapamycin (mTOR), mitogen-activated protein kinase (MAPK) and Myc pathways that can increase PD-L1 expression. A deeper understanding of PD-L1 expression regulation is crucial for improving strategies that exploit inhibition of this immune checkpoint in the clinic, especially in NSCLC where it is central in the therapeutic algorithm. We reviewed current preclinical and clinical data about PD-L1 expression regulation in NSCLC.

Keywords: PD-L1, PD-1, non-small-cell lung cancer, immunotherapy, immune checkpoint inhibitors, T-cell



https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7692442/

Upregulation of PD-L1 by EGFR Activation Mediates the Immune Escape in EGFR-Driven NSCLC: Implication for Optional Immune Targeted Therapy for NSCLC Patients with EGFR Mutation


Abstract

Introduction: Epidermal growth factor receptor (EGFR) mutation status was reported to be associated with programmed death-ligand 1 (PD-L1) expression. However, the molecular mechanism of PD-L1 regulation by EGFR activation and the potential clinical significance of blocking PD-1/PD-L1 in EGFR-mutant non-small-cell lung cancer (NSCLC) treated with EGFR tyrosine kinase inhibitors (TKIs) were largely unknown.

Methods: Western blot, real-time polymerase chain reaction, immunofluorescence, and flow cytometry were employed to explore the association between PD-L1 and EGFR activation. Then, we used EGFR-TKIs and downstream pathways inhibitors to clarify the detailed signaling pathway involved in PD-L1 regulation. Cell apoptosis, viability, and enzyme-linked immunosorbent assay test were used to study the immune suppression by EGFR activation and immune reactivation by EGFR-TKIs and/or PD-1 blocking in tumor cells and human peripheral blood mononuclear cells coculture system.

Results: We found that EGFR activation by EGF stimulation, exon-19 deletions, and L858R mutation could induce PD-L1 expression. EGFR activation upregulated PD-L1 through p-ERK1/2/p-c-Jun but not through p-AKT/p-S6 pathway. PD-L1 mediated by EGFR activation could induce the apoptosis of T cells through PD-L1/PD-1 axis in tumor cells and peripheral blood mononuclear cells coculture system. Inhibiting EGFR by EGFR-TKIs could free the inhibition of T cells and enhance the production of interferon-γ. Synergistic tumor cell killing effects were not observed with EGFR-TKIs and anti-PD-1 antibody combination treatment in coculture system.

Conclusions: Our results imply that EGFR-TKIs could not only directly inhibit tumor cell viability but also indirectly enhance antitumor immunity through the downregulation of PD-L1. Anti-PD-1/PD-L1 antibodies could be an optional therapy for EGFR-TKI sensitive patients, especially for EGFR-TKIs resistant NSCLC patients with EGFR mutation. Combination of EGFR-TKIs and anti-PD-1/PD-L1 antibodies treatment in NSCLC is not supported by the current study but warrant more studies to move into clinical practice.



https://pubmed.ncbi.nlm.nih.gov/25658629/

Abstract

Exposure to hydrogen peroxide (H2O2), one of the reactive oxidants in the gas phase of cigarette smoke (CS), induces aberrant phosphorylation of the epidermal growth factor receptor (EGFR), resulting in the lack of ubiquitination by c-Cbl, and impaired degradation. EGFR activation without the feedback regulation of normal degradation leads to uncontrolled cell growth and tumor promotion. Using immunoprecipitation, immunoblotting, and confocal microscopy, we now demonstrate that the pattern of EGFR activation by CS is similar to H2O2. We found that exposure of human airway epithelial cells to CS, as with exposure to H2O2, not only results in an increase in EGFR activation over time, but the EGFR activated by H2O2 or CS is neither ubiquitinated nor subsequently degraded due to its inability to bind the E3 ubiquitin ligase, c-Cbl, either directly or indirectly via the Grb2 adapter protein. Moreover, the stabilized H2O2- and CS-activated EGFR remains plasma membrane-bound, while a population of the receptor is trafficked to a perinuclear region. Concomitantly, CS exposure results in the activation of downstream Akt and ERK1/2 survival and proliferation pathways. Therefore, exposure to CS, like exposure to H2O2, results in prolonged signaling by the EGFR and may contribute to uncontrolled lung cell growth.

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4370285/

Epidermal growth factor receptor exposed to cigarette smoke is aberrantly activated and undergoes perinuclear trafficking

Medical Definition of perinuclear
: situated around or surrounding the nucleus of a cell perinuclear structures.

Abstract cont..



The epidermal growth factor (EGF) receptor (EGFR) is implicated in a number of cancers, and its oncogenic potential is linked to its inability to undergo clathrin-mediated endocytosis and lysosomal degradation (1, 2). The process of EGFR down-regulation is highly dependent on the ability of the E3 ubiquitin ligase, c-Cbl, to bind the receptor, thereby facilitating its entry into the clathrin-coated pits and lysosomal sorting (3–6). Recent evidence has also demonstrated the requirement of Grb2 in recruiting the RING domain of c-Cbl to the EGFR and for subsequent receptor entry into the clathrin-mediated endocytic pathway (7).

Our previous studies have demonstrated that oxidative stress induced by H2O2 causes the aberrant phosphorylation of the EGFR, where Tyr-1045, the c-Cbl binding site, is not phosphorylated and c-Cbl binding is abrogated (8). Therefore, under H2O2-induced oxidative stress, the EGFR is not only activated, but it is also stabilized due to its inability to enter the clathrin-mediated endocytic and lysosomal degradation pathways (8, 9). To further investigate the physiological relevance of oxidant-induced activation and stabilization of the EGFR, we focused our studies on cigarette smoke.

Among the plethora of deleterious chemicals found in cigarette smoke, H2O2 has been reported to be a significant constituent of the gas phase (10). We thus hypothesized that if mainstream cigarette smoke does indeed contain high amounts of H2O2, the effects of exposure on EGFR activation and stability should parallel those of H2O2 alone. To test this hypothesis, we utilized human airway epithelial cells in culture as a highly simplified model system in which to expose mainstream cigarette smoke. We examined EGFR phosphorylation, in association with c-Cbl, ubiquitination, and trafficking as determinants of receptor activation and stability. We also assessed the ability of cigarette smoke to activate downstream survival and proliferative signaling molecules such as Akt and extracellular signal-regulated kinase 1/2 (ERK1/2). The results herein demonstrate that the effects of cigarette smoke do indeed parallel those of H2O2, where the EGFR is aberrantly phosphorylated and stabilized due to the loss of c-Cbl binding and receptor ubiquitination. Moreover, the Akt and ERK1/2 pathways are also activated by cigarette smoke, thereby contributing to cellular events that may ultimately lead to hyperplasia and tumorigenesis.



Does secondhand smoke contain harmful chemicals?
Yes. Many of the harmful chemicals that are in the smoke inhaled by smokers are also found in secondhand smoke (1, 3, 6, 7), including some that cause cancer (1, 3, 7, 8).

These include:

Benzene
Tobacco-specific nitrosamines
Benzo[α]pyrene
1,3–butadiene (a hazardous gas)
Cadmium (a toxic metal)
Formaldehyde
Acetaldehyde
Many factors affect which chemicals and how much of them are found in secondhand smoke. These factors include the type of tobacco used in manufacturing a specific product, the chemicals (including flavorings such as menthol) added to the tobacco, the way the tobacco product is smoked, and—for cigarettes, cigars, little cigars, and cigarillos—the material in which the tobacco is wrapped (1–3, 7).

https://www.cancer.gov/about-cancer/cau ... fact-sheet