Nuclear Epidermal Growth Factor Receptor Research Articles

#501 Evaluation of the accuracy of serum creatinine-based GFR calculations across the different levels of renal function among Filipinos

Abstract Background and Aims Chronic kidney disease (CKD) is a worldwide health concern which continues to increase in prevalence. Early studies have evaluated kidney function by measuring serum creatinine (sCr) and/or the estimated glomerular filtration rate (eGFR). To date, there are limited studies that correlate nuclear GFR scans and eGFR by equations that include the Cockroft-Gault (CG), Modification of Diet in Renal Disease (MDRD), and Chronic Kidney Disease Epidemiology Collaboration equation (CKD-EPI) 2021 in Asians, specifically in a Filipino population. This study aims to compare the accuracy of GFR scan results and GFR estimated from the formulas across different levels of kidney functions, age groups, gender, and co-morbidities among a Filipino subset. Method A cross-sectional study was done among 2986 patients who underwent Nuclear GFR scan in a single kidney center. Results obtained were compared to estimated GFR results. Weighted Kappa and Bland-Altman Analyses were used to test for agreement between the measured and estimated GFR results. Results Absolute GFR values derived from the three equations demonstrated moderate reliability with results from nuclear scan when intraclass correlation coefficients were calculated with CKD-EPI 2021 being the highest. When further categorized into GFR levels, there was substantial level of agreement between each equation and GFR scan, with all weighted kappa coefficients being at least 0.700 with CG having the highest result (Table 1). Furthermore, when subgroup analysis was done according to age group, gender, and comorbidities, CG was found to be the most accurate per category (Table 2). Conclusion CKD-EPI 2021 was the most accurate in the actual GFR values however we cannot fully eliminate the utility of CG due to its categorical accuracy and in monitoring the deterioration of renal function.

ARF4-mediated retrograde trafficking as a driver of chemoresistance in GBM.

Cellular functions hinge on the meticulous orchestration of protein transport, both spatially and temporally. Central to this process is retrograde trafficking, responsible for targeting proteins to the nucleus. Despite its link to many diseases, the implications of retrograde trafficking in glioblastoma (GBM) are still unclear. To identify genetic drivers of TMZ resistance, we conducted comprehensive CRISPR-knockout screening, revealing ADP-ribosylation factor 4 (ARF4), a regulator of retrograde trafficking, as a major contributor. Suppressing ARF4 significantly enhanced TMZ sensitivity in GBM patient-derived xenograft (PDX) models, leading to improved survival rates (p<0.01) in both primary and recurrent lines. We also observed that TMZ exposure stimulates ARF4-mediated retrograde trafficking. Proteomics analysis of GBM cells with varying levels of ARF4 unveiled the influence of this pathway on EGFR signaling, with increased nuclear trafficking of EGFR observed in cells with ARF4 overexpression and TMZ treatment. Additionally, spatially-resolved RNA-sequencing of GBM patient tissues revealed substantial correlations between ARF4 and crucial nuclear EGFR (nEGFR) downstream targets, such as MYC, STAT1, and DNA-PK. Decreased activity of DNA-PK, a DNA repair protein downstream of nEGFR signaling that contributes to TMZ resistance, was observed in cells with suppressed ARF4 levels. Notably, treatment with DNA-PK inhibitor, KU57788, in mice with a recurrent PDX line resulted in prolonged survival (p<0.01), highlighting the promising therapeutic implications of targeting proteins reliant on ARF4-mediated retrograde trafficking. Our findings demonstrate that ARF4-mediated retrograde trafficking contributes to the development of TMZ resistance, cementing this pathway as a viable strategy to overcome chemoresistance in GBM.

Abstract A033: Nuclear EGFR as a regulator of the tumor microenvironment

Abstract Overexpression of the Epidermal Growth Factor Receptor (EGFR) is observed in all subtypes of breast cancer and is associated with large tumor size, poor differentiation, and poor clinical outcomes. However, the role of EGFR in driving the disease remains unclear, as EGFR-targeted antibodies and tyrosine kinase inhibitors fail to work effectively in breast cancer patients with EGFR overexpression. A possible explanation for therapeutic resistance is the role of intracellular EGFR, where retrograde trafficking of EGFR to the nucleus results in EGFR functioning directly as a transcriptional cofactor, regulating the expression of genes that promote tumor growth, metastasis, and an immune suppressive microenvironment. Our goal is to understand how targeting nuclear EGFR impacts this microenvironment. Using a novel therapeutic peptide (cSNX1.3) that targets retrograde trafficking of EGFR, we discovered that inhibiting retro-translocation of EGFR elicited an immune response as demonstrated by the secretion of inflammatory cytokines. Using RNA-Seq analysis, we detected an increase in the expression of cytokine receptors and natural killer (NK) cell ligands, such as RAET1 and AICL. We demonstrated that this active immune microenvironment is not observed when we treat with the EGFR kinase inhibitor Erlotinib, indicating a nuclear EGFR-specific outcome. Studies from tumor-bearing WAP-TGFα transgenic mice (an EGFR-dependent model of breast cancer) found the presence of NK cells and the expression of their activating ligands and receptors, IL-33 and SLAM7, respectively, in the tumor microenvironment. We hypothesize that nuclear EGFR is suppressing the expression of inflammatory cytokines, receptors, and ligands important for activation and recruitment of NK cells, thereby allowing immune evasion and ultimately progression of the disease. Future studies will investigate the potential to combine nuclear EGFR inhibitors with immunotherapies to activate the tumor immune microenvironment and promote optimal therapeutic efficacy. Citation Format: Angelica Escoto. Nuclear EGFR as a regulator of the tumor microenvironment [abstract]. In: Proceedings of the AACR Special Conference in Cancer Research: Advances in Breast Cancer Research; 2023 Oct 19-22; San Diego, California. Philadelphia (PA): AACR; Cancer Res 2024;84(3 Suppl_1):Abstract nr A033.

Abstract A031: The role of nuclear epidermal growth factor receptor in cell migration and wound healing

Abstract In breast cancer cells, epidermal growth factor receptor (EGFR) can retrotranslocate to the nucleus where it acts as a transcription cofactor and activates pro-oncogenic pathways such as stemness and migration. This retrotranslocation can occur through interaction with the BAR domain-containing protein Sorting Nexin 1 (SNX1). Upon retrotranslocation, EGFR is removed from the membrane via the Sec61 translocon, where the now soluble EGFR can interact with heat shock proteins and nuclear importins via its conserved nuclear localization sequence (NLS). Presence of the NLS in all wildtype EGFR indicates nuclear EGFR (nEGFR) also plays a role in non-cancerous tissue. EGFR is a known contributor to wound-healing, migration, and mammary gland development but the role of nEGFR in these processes has yet to be elucidated. Our lab has created cSNX1.3, a peptide-based therapeutic that recapitulates the BAR domain of Sorting Nexin 1. CSNX1.3 competitively binds to EGFR to prevent nuclear trafficking, and this treatment is effective at killing cancer cells that express EGFR, while leaving non-cancerous cells alive. In addition, cSNX1.3 is a potent inhibitor of EGF-dependent cell migration in Triple Negative Breast Cancer cell lines. Based on this data, we hypothesize that, in response to a wound, nEGFR activates cell migration pathways to promote wound healing. To better understand the role of nEGFR in wound healing and migration of non-cancer cell types, we have utilized CRISPR/Cas9 to insert mScarlet or mVenus, improved fluorescent proteins, onto the C-terminus of endogenous EGFR in immortalized MCF10A cells. Using a live cell imaging platform, we discovered that cells on the leading edge of a wound have increased levels of nEGFR. Furthermore, treatment with cSNX1.3 inhibits the migration of MCF10As and reduces levels of nEGFR. This data implies a role for nEGFR in the migration of MCF10As during wound healing. Future studies will delve deeper into the triggers of EGFR retrotranslocation to the nucleus and investigate the specific proteins nEGFR interacts with to affect cell migration. By elucidating the intrinsic role of nuclear EGFR in non-cancerous tissue types, we can better understand how cancer takes advantage of these molecular pathways and possibly its role in the cell migration essential to metastatic progression. Citation Format: Danielle M DiFranco, Joyce Schroeder. The role of nuclear epidermal growth factor receptor in cell migration and wound healing [abstract]. In: Proceedings of the AACR Special Conference in Cancer Research: Advances in Breast Cancer Research; 2023 Oct 19-22; San Diego, California. Philadelphia (PA): AACR; Cancer Res 2024;84(3 Suppl_1):Abstract nr A031.

Abstract B028: Investigating immune activity caused by a novel anti-cancer cell penetrating peptide

Abstract Activating the immune system against cancerous cells represents a promising therapy against multiple cancer types, particularly breast cancer. The epidermal growth factor receptor (EGFR) represents an emerging target in immunotherapy. A novel anti-cancer cell penetrating peptide was recently discovered to affect immune recruitment and potentially function in a murine model of breast cancer. This peptide, termed cSNX1.3, is a targeted therapy to block the nuclear localization of the epidermal growth factor receptor (EGFR), a phenomenon thought to occur primarily in cancerous cells. This suggests that nuclear localized EGFR may play a role in suppressing an anti-cancer immune response. To gain a better understanding of this in vivo data, we used in vitro immune cell co-culture techniques, migration assays, and other techniques to investigate immune recruitment and function after cancer cells are treated with this novel peptide therapy. In addition, we are investigating the mechanism of cSNX1.3 mediated cell death to determine if it can induce immunogenic cell death. To determine if nuclear EGFR plays a role in immune cell suppression, we are using a CRISPR/Cas9 strategy to mutate the nuclear localization sequence. This will provide a valuable tool to better understand the seemingly cancer-specific trafficking phenomenon. Together, this work will expand our understanding of therapy induced immune cell recruitment and trafficking. Citation Format: Ryan Hecksel, Angelica Escoto, Joyce Schroeder. Investigating immune activity caused by a novel anti-cancer cell penetrating peptide [abstract]. In: Proceedings of the AACR Special Conference in Cancer Research: Advances in Breast Cancer Research; 2023 Oct 19-22; San Diego, California. Philadelphia (PA): AACR; Cancer Res 2024;84(3 Suppl_1):Abstract nr B028.

Nuclear epidermal growth factor receptor as a therapeutic target.

Epidermal growth factor receptor (EGFR) is one of the most well-studied oncogenes with roles in proliferation, growth, metastasis, and therapeutic resistance. This intense study has led to the development of a range of targeted therapeutics including small-molecule tyrosine kinase inhibitors (TKIs), monoclonal antibodies, and nanobodies. These drugs are excellent at blocking the activation and kinase function of wild-type EGFR (wtEGFR) and several common EGFR mutants. These drugs have significantly improved outcomes for patients with cancers including head and neck, glioblastoma, colorectal, and non-small cell lung cancer (NSCLC). However, therapeutic resistance is often seen, resulting from acquired mutations or activation of compensatory signaling pathways. Additionally, these therapies are ineffective in tumors where EGFR is found predominantly in the nucleus, as can be found in triple negative breast cancer (TNBC). In TNBC, EGFR is subjected to alternative trafficking which drives the nuclear localization of the receptor. In the nucleus, EGFR interacts with several proteins to activate transcription, DNA repair, migration, and chemoresistance. Nuclear EGFR (nEGFR) correlates with metastatic disease and worse patient prognosis yet targeting its nuclear localization has proved difficult. This review provides an overview of current EGFR-targeted therapies and novel peptide-based therapies that block nEGFR, as well as their clinical applications and potential for use in oncology.

Determination of binding affinities between nuclear localization signal peptides of irradiated EGFR and KPNA using single‐molecule pull‐down assay and development of assay system for inhibitor screening

AbstractEpidermal growth factor receptor (EGFR) is transported into the nucleus during irradiation therapy and can cause the radiation resistance. It has been shown that irradiation activates EGFR transport to the nuclear by karyopherin alpha (KPNA) in the classical pathway, whereas ligand‐activated EGFR binds with karyopherin subunit beta 1 (KPNB1). Phosphorylation of T654 located within the nuclear localization signal (NLS) of EGFR is known to activate radiation‐induced nuclear EGFR transport. Therefore, we investigated the binding affinities between the NLS peptides of EGFR (645RRRHIVRKRXLRR657) and KPNA using a single‐molecule pull‐down assay in this study. We also showed the possible assay system for developing small molecules to modulate nuclear EGFR transport by high throughput screening, which potentially reduces the resistance during radiation therapy.

Nuclear Epidermal Growth Factor Receptor Overexpression as a Survival Predictor in Oral Squamous Cell Carcinoma.

The aim of this study was to determine, by immunohistochemical methods, the expression of nEGFR and markers of cell proliferation (Ki-67), cell cycle (mEGFR, p53, cyclin D1), and tumor stem cells (ABCG2) in 59 pathohistological samples of healthy oral mucosa, 50 oral premalignant changes (leukoplakia and erythroplakia), and 52 oral squamous cell carcinomas (OSCC). An increase in the expression of mEGFR and nEGFR was found with the development of the disease (p < 0.0001). In the group of patients with leukoplakia and erythroplakia, we found a positive correlation between nEGFR and Ki67, p53, cyclin D1, and mEGFR, whereas in the group of patients with OSCC, we found a positive correlation between nEGFR and Ki67, mEGFR (p < 0.05). Tumors without perineural (PNI) invasion had a higher expression of p53 protein than tumors with PNI (p = 0.02). Patients with OSCC and overexpression of nEGFR had shorter overall survival (p = 0.004). The results of this study suggest a potentially important independent role of nEGFR in oral carcinogenesis.

DDDR-08. ARF4-MEDIATED RETROGRADE TRAFFICKING AS A MECHANISM OF CHEMORESISTANCE IN GLIOBLASTOMA

Abstract Glioblastoma (GBM) remains a deadly disease with an extremely poor prognosis, owing largely to its high rate of resistance to conventional temozolomide (TMZ) chemotherapy. To identify the unknown drivers of this chemoresistance, we performed a genome-wide CRISPR knockout sensitivity screen. Results showed significant enrichment of ~200 novel genes, including ARF4, a previously unstudied gene involved in retrograde trafficking—a well-regulated process by which cargo is transported internally from endosomes to ultimately the nucleus. Initial investigation showed that ARF4-knockdowns resulted in significantly heightened susceptibility to TMZ in multiple GBM patient-derived xenograft lines and extended survival compared to the controls (p&amp;lt; 0.01) in vivo in both primary and recurrent lines. Live-cell imaging further revealed that ARF4-knockdowns significantly inhibited retrograde trafficking, while ARF4-overexpressions resulted in an untenable increase in retrograde trafficking (p &amp;lt; 0.001) in vitro. Enhanced trafficking was also observed in TMZ-treated cells (p &amp;lt; 0.001), suggesting that ARF4 may drive dysregulation of retrograde trafficking to promote chemoresistance.We then performed an unbiased proteomics screen in control and ARF4-knockdown GBM cells with and without therapy to identify which proteins were being uniquely transported to the nucleus during therapy as a result of ARF4-mediated retrograde trafficking. Results showed the greatest enrichment of EGFR signaling, as validated by an increase in EGFR trafficking and nuclear EGFR expression in ARF4-overexpression and TMZ-treated conditions and a decrease of this phenomenon in ARF4-knockdown conditions.We also show that DNA-PK, a DNA repair protein that is transcriptionally activated by nuclear EGFR, is similarly downregulated in ARF4-knockdown conditions and elevated in ARF4-overexpression and TMZ-treated conditions. Treatment with DNA-PK-inhibitor, KU57788, resulted in extended survival compared to the controls (p &amp;lt; 0.01) in vivo in a recurrent line, indicating potential clinical benefit from targeting this pathway. Overall, we present a novel understanding of how ARF4 acts during therapy to increase nuclear localization of chemoresistance-promoting proteins.

Human Papillomavirus Oncoproteins Confer Sensitivity to Cisplatin by Interfering with Epidermal Growth Factor Receptor Nuclear Trafficking Related to More Favorable Clinical Survival Outcomes in Non-Small Cell Lung Cancer.

High-risk human papillomavirus (HPV) infections and epidermal growth factor receptor (EGFR) expression have been reported to be associated with more favorable survival outcomes in lung adenocarcinoma patients. In this study, we utilized transfected HPV 16E5/16E6/16E7 H292 cells to investigate the mechanism of HPV oncoproteins interfering with EGFR nuclear trafficking related to a better response to cisplatin. Furthermore, we correlated HPV 16E6/18E6 expression and differentially localized EGFR expression with the clinical association and survival impact in lung adenocarcinoma patients. Our results found significantly higher phosphorylated nuclear EGFR expression upon epidermal growth factor stimulus and better responses to cisplatin in transfected HPV 16E5/16E6/16E7 NCI-H292 cells and xenograft animal models. Our data were compatible with clinical results of a high correlation of HPV 16E6/18E6 and EGFR expression in non-small cell lung cancer tissues and the synergistic effects of both with the best survival prognosis in a lung adenocarcinoma cohort, especially in patients with older age, no brain metastasis, smoking history, and wild-type EGFR status. Cumulatively, our study supports HPV 16E5/16E6/16E7 oncoproteins interfering with EGFR nuclear trafficking, resulting in increased sensitivity to cisplatin. HPV 16E6/18E6 and EGFR expression serve as good prognostic factors in lung adenocarcinoma patients.

Nuclear-targeted EGF receptor enhances proliferation and migration of human anaplastic thyroid cancer cells.

Epidermal growth factor (EGF) has various important physiological functions, which it exerts by binding to the epidermal growth factor receptor (EGFR). Reports show that EGF expression is strongly correlated with the occurrence and development of many types of tumour. To date, however, the relationship between EGF/EGFR and the occurrence and development of thyroid carcinoma remains unclear. In the current study, we investigated this phenomenon using human anaplastic thyroid carcinoma cell lines (SUN-80). The results indicated that EGF triggered the EGFR-mediated intracellular signalling pathway, including signal transducers and activators of transcription 1/3/5 (STAT1/3/5) and protein kinase B (AKT) in a time- and dose-dependent manner. In addition, results from EGF-induced EGFR internalization and co-localization analyses showed that clathrin, Rab5/7, and EEA1 play critical roles in the intracellular trafficking of EGF/EGFR. Interestingly, EGF triggered EGFR translocation into the nucleus, while nuclear-localized EGFR affected cell cycle distribution, thereby significantly promoting the ration of S phase. Overall, these findings indicated that nuclear EGFR exerts biological activity and physiological functions, including changing cell cycle, which in turn promotes proliferation and migration of SUN-80 cells. These findings lay a foundation for further explorations seeking to understand the biological effects of the EGF/EGFR system on the occurrence and development of thyroid cancer.

OS08.6.A Novel role of ARF4-mediated retrograde trafficking as a driver of chemoresistance in GBM

Abstract Background Glioblastoma (GBM) is the most common type of adult malignant brain tumor, with a median survival of only 21 months. This is partly due to the high rate of resistance to conventional therapy, including temozolomide (TMZ), leading to recurrence rates close to 100%. To identify the unknown genes driving the development of this resistance, we performed a genome-wide CRISPR knockout screen comparing a DMSO-treated population with a TMZ-treated population over 14 days. Results showed substantial enrichment of ~200 novel genes, including a previously unstudied gene ARF4—involved in retrograde trafficking to the nucleus. Here, we set out to characterize the mechanism by which ARF4 may be acting to promote chemoresistance. Material and Methods A whole-genome CRISPR-Cas9 sensitivity screen as well as a variety of in vitro and in vivo experiments, such as live-cell imaging, cell viability assays, and western blotting were conducted. Results Initial investigation into ARF4 showed significant elevations in expression at RNA and protein levels (p&amp;lt;0.05) in recurrent patient tumors, as well as a significant survival benefit in patient datasets when downregulated (p&amp;lt;0.05). Knocking out ARF4 resulted in significantly heightened sensitivity to TMZ in multiple GBM patient-derived xenograft lines and extended survival compared to the controls (p&amp;lt;0.01) in vivo. Further investigation via live-cell imaging of transferrin receptors, a retrograde transport marker, revealed that ARF4-knockdowns significantly inhibited retrograde trafficking, while ARF4-overexpressions resulted in an untenable increase in retrograde trafficking in vitro. This effect was also seen in TMZ-treated cells, which displayed enhanced trafficking dynamics, suggesting that ARF4-mediated retrograde trafficking is elevated during therapy to drive nuclear localization of key chemoresistance-promoting factors. We then performed an unbiased proteomics screen to identify which genes were being uniquely transported to the nucleus as a product of ARF4-mediated retrograde trafficking, which revealed enrichment of the EGFR signaling pathway in particular. Validation experiments confirmed a decrease in EGFR trafficking and nuclear EGFR expression in ARF4-knockdowns and an increase in EGFR trafficking and nuclear EGFR expression in ARF4-overexpression and TMZ-treated GBM cells. Furthermore, nuclear DNA-PK, a DNA repair protein known to be transcriptionally activated by EGFR, was similarly found to be downregulated in ARF4-knockdown conditions and elevated in ARF4-overexpression and TMZ-treated conditions. Conclusion: Here, we show that ARF4 may be responsible for promoting chemoresistance through altered retrograde trafficking of EGFR specifically. Thus, our study has yielded a promising and novel therapeutic target for GBM, a disease desperately in need of new therapeutic strategies.

Significance of nuclear EGFR and ABCG2 expression in malignant transformation of oral potentially malignant disorders.

The purpose of this study was to investigate the expression of nuclear EGFR (nEGFR) and the stem cell marker ABCG2 in oral leukoplakia (OL) and oral erythroplakia (OE) and to assess their significance as prognostic biomarkers for malignant transformation. In this study we included 50 patients with oral potentially malignant disorders (OPMD), 31 with OL and 19 with OE, in whom we examined the expression of nEGFR and ABCG2 by immunohistochemical methods. Twenty-one (42%) of 50 patients with OL and OE developed oral squamous cell carcinoma (OSCC). The malignant transformation was increased 12,84-fold (95% CI, 2.15-76.44, p=0.005) in OPMD expressing both ABCG2 and nEGFR. Expression of nEGFR is a strong indicator of malignant transformation, unlike ABCG2 expression, respectively. Determining the co-expression of the biomarkers nEGFR and ABCG2 in OPMD may serve us to determine the risk of malignant transformation in OSCC.

Abstract LB096: EGFR-dependent inflammation as a driver of breast cancer

Abstract Triple Negative Breast Cancer (TNBC) is one of the most aggressive and metastatic subtypes of hormone receptor negative breast cancers. Evidence supports that most patients with TNBC overexpress the Epidermal Growth Factor Receptor (EGFR), yet its role in driving the disease remains unclear. Therapies have been developed to target EGFR, but EGFR-targeted antibodies and tyrosine kinase inhibitors fail to work effectively in breast cancer patients. A possible explanation is that in addition to its canonical function at the membrane, EGFR has a non-canonical function where it can undergo retrograde trafficking to the nucleus, making it resistant to antibody-based therapeutics. Once in the nucleus, EGFR is known to function as a transcriptional cofactor for STAT3, STAT5, and E2F1, thereby regulating the expression of genes that promote inflammation and cell proliferation. Via RNA-Seq analysis, we demonstrate that EGFR can regulate different subsets of genes depending on its canonical signaling activity or nuclear role. Our goal is to understand and distinguish this difference in regulation to assess how EGFR affects inflammation. We hypothesize that EGFR is modifying inflammation differently depending on its canonical or non-canonical role, thereby driving disease progression in multiple ways. We have found that canonical EGFR can induce interleukin 8 while nuclear EGFR can repress interleukin 6 through the use of either kinase inhibitors (IL8) or blocking nuclear translocation of EGFR (IL6). Correlated with these changes are alterations in growth and inflammatory profiles in both a triple negative inflammatory mouse model and an EGFR-driven breast cancer mouse model. We are now investigating the role of nuclear-EGFR-dependent inflammation in driving tumor progression. Understanding the different mechanisms by which EGFR modifies inflammation and the tumor microenvironment would allow us to develop more specific targets for patients with TNBC. Citation Format: Angelica Escoto. EGFR-dependent inflammation as a driver of breast cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr LB096.

Dihydroconiferyl Ferulate Isolated from Dendropanax morbiferus H.Lév. Suppresses Stemness of Breast Cancer Cells via Nuclear EGFR/c-Myc Signaling.

Breast cancer is the leading cause of global cancer incidence and breast cancer stem cells (BCSCs) have been identified as the target to overcome breast cancer in patients. In this study, we purified a BCSC inhibitor from Dendropanax morbiferus H.Lév. leaves through several open column and high-performance liquid chromatography via activity-based purification. The purified cancer stem cell (CSC) inhibitor was identified as dihydroconiferyl ferulate using nuclear magnetic resonance and mass spectrometry. Dihydroconiferyl ferulate inhibited the proliferation and mammosphere formation of breast cancer cells and reduced the population of CD44high/CD24low cells. Dihydroconiferyl ferulate also induced apoptosis, inhibited the growth of mammospheres and reduced the level of total and nuclear EGFR protein. It suppressed the EGFR levels, the interaction of Stat3 with EGFR, and c-Myc protein levels. Our findings show that dihydroconiferyl ferulate reduced the level of nuclear epidermal growth factor receptor (EGFR) and induced apoptosis of BCSCs through nEGFR/Stat3-dependent c-Myc deregulation. Dihydroconiferyl ferulate exhibits potential as an anti-CSC agent through nEGFR/Stat3/c-Myc signaling.

RNA-binding protein p54nrb/NONO potentiates nuclear EGFR-mediated tumorigenesis of triple-negative breast cancer

Nuclear-localized epidermal growth factor receptor (EGFR) highly correlates with the malignant progression and may be a promising therapeutic target for breast cancer. However, molecular mechanisms of nuclear EGFR in triple-negative breast cancer (TNBC) have not been fully elucidated. Here, we performed gene-annotation enrichment analysis for the interactors of nuclear EGFR and found that RNA-binding proteins (RBPs) were closely associated with nuclear EGFR. We further demonstrated p54nrb/NONO, one of the RBPs, significantly interacted with nuclear EGFR. NONO was upregulated in 80 paired TNBC tissues and indicated a poor prognosis. Furthermore, NONO knockout significantly inhibited TNBC proliferation in vitro and in vivo. Mechanistically, NONO increased the stability of nuclear EGFR and recruited CREB binding protein (CBP) and its accompanying E1A binding protein p300, thereby enhancing the transcriptional activity of EGFR. In turn, EGFR positively regulated the affinity of NONO to mRNAs of nuclear EGFR downstream genes. Furthermore, the results indicated that the nuclear EGFR/NONO complex played a critical role in tumorigenesis and chemotherapy resistance. Taken together, our findings indicate that NONO enhances nuclear EGFR-mediated tumorigenesis and may be a potential therapeutic target for TNBC patients with nuclear EGFR expression.

Co-encapsulated nanoparticles of Erlotinib and Quercetin for targeting lung cancer through nuclear EGFR and PI3K/AKT inhibition

Erlotinib-based EGFR targeted therapy has proven significant clinical improvement against non-small cell lung cancer (NSCLC). However, the anticancer activity of Erlotinib (Ertb) is limited by the development of Ertb resistance and possess a challenge to clinicians and patients. To explore a better therapeutic strategy, we evaluated Ertb in combinations with different natural products. We identified that Ertb and Quercetin (Quer) combination is more synergistic against A549 and NCI H460 cells compared to Ertb with Fisetin/Carnosic acid/Luteolin. To further improve the efficacy and overcome the limitation of free therapeutics, Ertb and Quer loaded solid lipid nanoparticles (EQNPs) were prepared using Chitosan-MA-TPGS polymer by hot homogenization method. The drug-loaded nanoparticles (NPs) have shown high encapsulation efficiency (77% Ertb and 71.4% Quer) as well as small particle size of 87.3 ± 0.78 nm and positive zeta potential + 13.4 ± 1.12 mV. At pH 5.5, Ertb and Quer were released at their highest levels. We found that, EQNPs decreased the expression of P-glycoprotein (P-gp) and nuclear epidermal growth factor receptor (nEGFR). EQNPs increased the uptake of Ertb and Quer, and apoptosis induction in Ertb resistant A549/ER cells. Further, in vivo EQNPs formulation have shown increased uptake of nanoparticles in the lung tissue and significantly reduced the expression of nEGFR. Thus, EQNPs may be developed as a targeted medicine with minimum side effects for treatment of NSCLC to improve the quality of life and survival of NSCLC patients.

Primaquine Inhibits the Endosomal Trafficking and Nuclear Localization of EGFR and Induces the Apoptosis of Breast Cancer Cells by Nuclear EGFR/Stat3-Mediated c-Myc Downregulation.

Triple-negative breast cancer (TNBC) cells overexpress the epidermal growth factor receptor (EGFR). Nuclear EGFR (nEGFR) drives resistance to anti-EGFR therapy and is correlated with poor survival in breast cancer. Inhibition of EGFR nuclear translocation may be a reasonable approach for the treatment of TNBC. The anti-malarial drugs chloroquine and primaquine have been shown to promote an anticancer effect. The aim of the present study was to investigate the effect and mechanism of chloroquine- and primaquine-induced apoptosis of breast cancer cells. We showed that primaquine, a malaria drug, inhibits the growth, migration, and colony formation of breast cancer cells in vitro, and inhibits tumor growth in vivo. Primaquine induces damage to early endosomes and inhibits the nuclear translocation of EGFR. Primaquine inhibits the interaction of Stat3 and nEGFR and reduces the transcript and protein levels of c-Myc. Moreover, primaquine and chloroquine induce the apoptosis of breast cancer cells through c-Myc/Bcl-2 downregulation, induce early endosome damage and reduce nEGFR levels, and induce apoptosis in breast cancer through nEGFR/Stat3-dependent c-Myc downregulation. Our study of primaquine and chloroquine provides a rationale for targeting EGFR signaling components in the treatment of breast cancer.

DDRE-24. ARF4-MEDIATED RETROGRADE TRAFFICKING PROMOTES CHEMORESISTANCE IN GBM

Abstract Glioblastoma (GBM) is the most common type of adult malignant brain tumor, with a median survival of only 21 months. This is partly due to the high rate of resistance to conventional therapy, including temozolomide (TMZ), leading to recurrence rates close to 100%. To identify the unknown genes driving the development of this resistance, we performed a genome-wide CRISPR knockout screen comparing a DMSO-treated population with a TMZ-treated population over 14 days. Results showed significant enrichment of ~200 novel genes and pathways. From this list, we identified 4 previously unstudied genes showing significant elevations in RNA expression (p&amp;lt; 0.05) when comparing recurrent and primary tumors in patient datasets, along with significant survival benefits corresponding to low gene expression (p&amp;lt; 0.05). Validation experiments in vitro showed significant elevations in RNA and protein expression in multiple patient-derived xenografts (PDX) lines during TMZ-treated conditions, while knocking out these genes also resulted in significantly heightened sensitivity to TMZ (p&amp;lt; 0.01). We investigated one particularly enriched gene, ARF4, known to be involved in retrograde trafficking. With previous studies showing that ARF4 is upregulated under ER stress, we first confirmed the increased expression of ER stress markers during TMZ treatment to explain the increased expression of ARF4 during treatment. Further investigation via live-cell imaging also showed a consequent increase in retrograde trafficking in TMZ-treated cells, as evidenced by significantly increased trafficking of transferrin receptors, a retrograde transport marker, as well as EGFR, known to play a role in promoting chemoresistance through strengthened DNA repair response. ARF4-overexpressed GBM cells similarly showed increased trafficking of transferrin receptors and EGFR to the nucleus, while ARF4-knockdowns showed decreased trafficking and nuclear EGFR expression. Ultimately, our CRISPR-Cas9 screen has identified a promising therapeutic target, ARF4, which may drive GBM’s robust resistance to chemotherapy through increased retrograde trafficking of chemoresistance-promoting nuclear EGFR.

Prognostic Impact of Membranous/Nuclear Epidermal Growth Factor Receptor Localization in Clear Cell Renal Cell Carcinoma.

EGFR is overexpressed in the majority of clear cell renal cell carcinomas (CCRCCs). Although EGFR deregulation was found to be of great significance in CCRCC biology, the EGFR overexpression is not associated with EGFR-targeted therapy responsiveness. Moreover, the prognostic role of EGFR expression remains controversial. In the present study, we evaluated the role played by EGFR overexpression in CCRCC and its prognostic significance associated with different immunohistochemical localization patterns. In our study, the Total Score (TS) related to membranous-cytoplasmic EGFR expression showed a significant correlation with grade, pathologic stage (pT), and Stage, Size, Grade, and Necrosis (SSIGN) score, and a negative correlation with nuclear EGFR expression. No significant correlations were shown between nuclear EGFR and clinic-pathological features. Additionally, a correlation between SGLT1 expression levels and pT was described. Multivariate analysis identifies pT and SSIGN score as independent prognostic factors for CCRCC. A significantly increased survival rate was found in the case of positive expression of nuclear EGFR and SGLT1. Based on our findings, SGLT1 and nuclear EGFR overexpression defines a subgroup of CCRCC patients with good prognosis. Membranous-cytoplasmic EGFR expression was shown to be a poor prognostic factor and could define a CCRCC subgroup with poor prognosis that should be responsive to anti-EGFR therapies.