EGFR transcriptionally upregulates UTX via STAT3 in non-small cell lung cancer.

BACKGROUND: Histone demethylase UTX has been reported to participate in the occurrence and development of many cancers in tissue-specific manners. However, the role of UTX in non-small cell lung cancer (NSCLC) and exactly what regulates the expression of UTX remains unclear. Here, we analyzed the role of UTX in NSCLC in association with the widely recognized tumor driver epidermal growth factor receptor (EGFR). METHODS: UTX levels in clinical samples were detected by immunohistochemistry staining, western blotting and real-time quantitative PCR. The expression of UTX in tumor tissue was correlated with the phosphorylation of EGFR. Cell proliferation and migration were evaluated by MTT and wound-healing assays. The impact of EGFR and its downstream pathways on UTX was explored with corresponding inhibitors, and examined by western blotting and real-time quantitative PCR. RESULTS: In this study, we found that the expression of UTX in cancer tissues of patients with NSCLC was significantly higher than that in paracancerous tissues, and positively associated with EGFR phosphorylation levels. In addition, in NSCLC cell lines, UTX can promote proliferation and migration, while inhibition of its enzyme activity suppressed cell growth. Moreover, UTX expression was significantly upregulated when EGFR signaling pathway was activated, and vice versa when EGFR pathway was inhibited by tyrosine kinase inhibitor. Further mechanistic studies suggested that the activation of EGFR activated its downstream JAK/STAT3 signaling pathway and promoted STAT3 phosphorylation; the phosphorylated STAT3 transcriptionally promoted the levels of UTX. CONCLUSIONS: These results suggest an "EGFR-STAT3-UTX" axis that plays an oncogenic role in NSCLC.

Activation of EGFR signaling by Tc-Vein and Tc-Spitz regulates the metamorphic transition in the red flour beetle Tribolium castaneum.

Animal development relies on a sequence of specific stages that allow the formation of adult structures with a determined size. In general, juvenile stages are dedicated mainly to growth, whereas last stages are devoted predominantly to the maturation of adult structures. In holometabolous insects, metamorphosis marks the end of the growth period as the animals stops feeding and initiate the final differentiation of the tissues. This transition is controlled by the steroid hormone ecdysone produced in the prothoracic gland. In Drosophila melanogaster different signals have been shown to regulate the production of ecdysone, such as PTTH/Torso, TGFß and Egfr signaling. However, to which extent the roles of these signals are conserved remains unknown. Here, we study the role of Egfr signaling in post-embryonic development of the basal holometabolous beetle Tribolium castaneum. We show that Tc-Egfr and Tc-pointed are required to induced a proper larval-pupal transition through the control of the expression of ecdysone biosynthetic genes. Furthermore, we identified an additional Tc-Egfr ligand in the Tribolium genome, the neuregulin-like protein Tc-Vein (Tc-Vn), which contributes to induce larval-pupal transition together with Tc-Spitz (Tc-Spi). Interestingly, we found that in addition to the redundant role in the control of pupa formation, each ligand possesses different functions in organ morphogenesis. Whereas Tc-Spi acts as the main ligand in urogomphi and gin traps, Tc-Vn is required in wings and elytra. Altogether, our findings show that in Tribolium, post-embryonic Tc-Egfr signaling activation depends on the presence of two ligands and that its role in metamorphic transition is conserved in holometabolous insects.

Mechanisms and management of 3rd­generation EGFR­TKI resistance in advanced non­small cell lung cancer (Review).

Targeted therapy with epidermal growth factor receptor (EGFR)­tyrosine kinase inhibitors (TKIs) is a standard modality of the 1st­line treatments for patients with advanced EGFR­mutated non­small cell lung cancer (NSCLC), and substantially improves their prognosis. However, EGFR T790M mutation is the primary mechanism of 1st­ and 2nd­generation EGFR­TKI resistance. Osimertinib is a representative of the 3rd­generation EGFR­TKIs that target T790M mutation, and has satisfactory efficacy in the treatment of T790M­positive NSCLC with disease progression following use of 1st­ or 2nd­generation EGFR­TKIs. Other 3rd­generation EGFR­TKIs, such as abivertinib, rociletinib, nazartinib, olmutinib and alflutinib, are also at various stages of development. However, the occurrence of acquired resistance is inevitable, and the mechanisms of 3rd­generation EGFR­TKI resistance are complex and incompletely understood. Genomic studies in tissue and liquid biopsies of resistant patients reveal multiple candidate pathways. The present review summarizes the recent findings in mechanisms of resistance to 3rd­generation EGFR­TKIs in advanced NSCLC, and provides possible strategies to overcome this resistance. The mechanisms of acquired resistance mainly include an altered EGFR signaling pathway (EGFR tertiary mutations and amplification), activation of aberrant bypassing pathways (hepatocyte growth factor receptor amplification, human epidermal growth factor receptor 2 amplification and aberrant insulin­like growth factor 1 receptor activation), downstream pathway activation (RAS/RAF/MEK/ERK and PI3K/AKT/mTOR) and histological/phenotypic transformations (SCLC transformation and epithelial­mesenchymal transition). The combination of targeted therapies is a promising strategy to treat osimertinib­resistant patients, and multiple clinical studies on novel combined therapies are ongoing.

The Epidermal Growth Factor Receptor Is a Relevant Host Factor in the Early Stages of The Zika Virus Life Cycle In Vitro.

Zika virus (ZIKV) is a flavivirus that is well known for the epidemic in the Americas in 2015 and 2016 in which microcephaly in newborns and other neurological complications were connected to ZIKV infection. Many aspects of the ZIKV viral life cycle, including binding and entry into the host cell, are still enigmatic. Based on the observation that CHO cells lack expression of the epidermal growth factor receptor (EGFR) and are not permissive for various ZIKV strains, the relevance of EGFR for the viral life cycle was analyzed. Infection of A549 cells by ZIKV leads to a rapid internalization of EGFR that colocalizes with the endosomal marker EEA1. Moreover, infection by different ZIKV strains is associated with an activation of EGFR and the subsequent activation of the mitogen-activated protein kinase (MAPK)/extracellular signal-regulated kinase (ERK) signaling cascade. However, treatment of the cells with methyl-ß-cyclodextrin (MßCD), which on the one hand leads to an activation of EGFR but on the other hand prevents EGFR internalization, impairs ZIKV infection. Specific inhibition of EGFR or of the Ras-Raf-MEK-ERK signal transduction cascade hinders ZIKV infection by inhibition of ZIKV entry. In accordance with this, knockout of EGFR expression impedes ZIKV entry. In the case of an already established infection, inhibition of EGFR or of downstream signaling does not affect viral replication. Taken together, these data demonstrate the relevance of EGFR in the early stages of ZIKV infection and identify EGFR as a target for antiviral strategies. IMPORTANCE These data deepen the knowledge about the ZIKV infection process and demonstrate the relevance of EGFR for ZIKV entry. In light of the fact that a variety of specific and efficient inhibitors of EGFR and of EGFR-dependent signaling have been developed and licensed, repurposing of these substances could be a helpful tool to prevent the spreading of ZIKV infection in an epidemic outbreak.

Tyrosine kinases regulate chondrocyte hypertrophy: promising drug targets for Osteoarthritis.

Osteoarthritis (OA) is a major health problem worldwide that affects the joints and causes severe disability. It is characterized by pain and low-grade inflammation. However, the exact pathogenesis remains unknown and the therapeutic options are limited. In OA articular chondrocytes undergo a phenotypic transition becoming hypertrophic, which leads to cartilage damage, aggravating the disease. Therefore, a therapeutic agent inhibiting hypertrophy would be a promising disease-modifying drug. The therapeutic use of tyrosine kinase inhibitors has been mainly focused on oncology, but the Food and Drug Administration (FDA) approval of the Janus kinase inhibitor Tofacitinib in Rheumatoid Arthritis has broadened the applicability of these compounds to other diseases. Interestingly, tyrosine kinases have been associated with chondrocyte hypertrophy. In this review, we discuss the experimental evidence that implicates specific tyrosine kinases in signaling pathways promoting chondrocyte hypertrophy, highlighting their potential as therapeutic targets for OA.

RASAL2 Confers Collateral MEK/EGFR Dependency in Chemoresistant Triple-Negative Breast Cancer.

PURPOSE: While chemotherapy remains the standard treatment for triple-negative breast cancer (TNBC), identifying and managing chemoresistant tumors has proven elusive. We sought to discover hallmarks and therapeutically actionable features of refractory TNBC through molecular analysis of primary chemoresistant TNBC specimens. EXPERIMENTAL DESIGN: We performed transcriptional profiling of tumors from a phase II clinical trial of platinum chemotherapy for advanced TNBC (TBCRC-009), revealing a gene expression signature that identified de novo chemorefractory tumors. We then employed pharmacogenomic data mining, proteomic and other molecular studies to define the therapeutic vulnerabilities of these tumors. RESULTS: We reveal the RAS-GTPase-activating protein (RAS-GAP) RASAL2 as an upregulated factor that mediates chemotherapy resistance but also an exquisite collateral sensitivity to combination MAP kinase kinase (MEK1/2) and EGFR inhibitors in TNBC. Mechanistically, RASAL2 GAP activity is required to confer kinase inhibitor sensitivity, as RASAL2-high TNBCs sustain basal RAS activity through suppression of negative feedback regulators SPRY1/2, together with EGFR upregulation. Consequently, RASAL2 expression results in failed feedback compensation upon co-inhibition of MEK1/2 and EGFR that induces synergistic apoptosis in vitro and in vivo. In patients with TNBC, high RASAL2 levels predict clinical chemotherapy response and long-term outcomes, and are associated via direct transcriptional regulation with activated oncogenic Yes-Associated Protein (YAP). Accordingly, chemorefractory patient-derived TNBC models exhibit YAP activation, high RASAL2 expression, and tumor regression in response to MEK/EGFR inhibitor combinations despite well-tolerated intermittent dosing. CONCLUSIONS: These findings identify RASAL2 as a mediator of TNBC chemoresistance that rewires MAPK feedback and cross-talk to confer profound collateral sensitivity to combination MEK1/2 and EGFR inhibitors.

EGFR inhibition blocks cancer stem cell clustering and lung metastasis of triple negative breast cancer.

Triple-negative breast cancer (TNBC) is one of the most aggressive and metastatic breast cancer subtypes lacking targeted therapy. Our recent work demonstrated that circulating tumor cell (CTC) clusters and polyclonal metastasis of TNBC are driven by aggregation of CD44+ cancer stem cells (CSC) and associated with an unfavorable prognosis, such as low overall survival. However, there is no existing therapeutic that can specifically block CTC or CSC cluster formation. Methods: Using patient-derived xenograft (PDX) models, we established an ex vivo tumor cell clustering assay for a pilot screening of blockade antibodies. After identifying EGFR as a target candidate, we modulated the gene expression and inhibited its kinase activity to determine its functional importance in tumor cell clustering and therapeutic inhibition of lung metastasis. We also examined the molecular regulation network of EGFR and a potential connection to CSC marker CD44 and microRNAs, which regulate CTC clustering. Results: We report here that EGFR inhibition successfully blocks circulating CSC (cCSC) clustering and lung metastasis of TNBC. EGFR enhances CD44-mediated tumor cell aggregation and CD44 stabilizes EGFR. Importantly, blocking EGFR by a novel anti-EGFR monoclonal antibody (clone LA1) effectively blocked cell aggregation in vitro and reduced lung metastasis in vivo. Furthermore, our data demonstrated that the tumor suppressor microRNA-30c serves as another negative regulator of cCSC clustering and lung metastasis by targeting CD44 as well as its downstream effector EGFR. Conclusion: Our studies identify a novel anti-EGFR therapeutic strategy to inhibit cCSC aggregation and therefore abolish cCSC cluster-mediated metastasis of TNBC.

CircMYBL2 regulates the resistance of cervical cancer cells to paclitaxel via miR-665-dependent regulation of EGFR.

Circular RNAs are considered to be associated with cancer resistance. This study aims to investigate the function and mechanism of circMYBL2 in paclitaxel (PTX) resistance of cervical cancer (CC). The expression of circMYBL2, miR-665 and epidermal growth factor receptor (EGFR) was investigated using quantitative real-time polymerase chain reaction assay. Cell viability, cell colony number, cell proliferation, apoptosis and lactate dehydrogenase (LDH) were detected by 3-(4, 5-Dimethylthiazol-2-yl)-2, 5-diphenyltetrazolium bromide, colony formation, 5-ethynyl-2'-deoxyuridine incorporation, flow cytometry and LDH release assays, respectively. The interaction between miR-665 and circMYBL2 or EGFR was confirmed by dual-luciferase reporter assay. The protein expression levels were quantified by western blot or immunohistochemistry assay. Mice xenograft models were constructed to investigate the effect of circMYBL2 on CC tumor growth. CircMYBL2 was upregulated in CC tissues and cells, especially in PTX-resistant CC tissues and cells, and it was a stable circRNA mainly distributed in the cytoplasm. CircMYBL2 could enhance the PTX resistance of CC cells in vitro and promote CC tumor growth in vivo. Mechanistically, circMYBL2 could inhibit the PTX sensitivity and promote cell malignant behaviors in PTX-sensitive and PTX-resistant CC cells via upregulating EGFR mediated by miR-665. CircMYBL2 played a positive role in the PTX resistance and malignant activities of PTX-sensitive and PTX-resistant CC cells by regulating the miR-665/EGFR network, providing a novel therapeutic strategy for the treatment of CC patients resistant to PTX.

Growth Hormone Modulation of Hepatic Epidermal Growth Factor Receptor Signaling.

Epidermal growth factor receptor (EGFR) signaling has a central role in the regenerative response of the liver upon injury and is involved in cellular transformation linked to chronic damage. Hepatic EGFR expression, trafficking, and signaling are regulated by growth hormone (GH). Chronically elevated GH levels are associated with liver cancer development and progression in mice. Studies in different in vivo experimental models indicate that EGF and GH mutually crossregulate in a complex manner. Several factors, such as the extent of exposure to supraphysiological GH levels and the pattern of GH administration, are important variables to be considered in exploring the interplay between the two hormones in connection with the progression of hepatic tumors.

CD73 Is Regulated by the EGFR-ERK Signaling Pathway in Non-small Cell Lung Cancer.

BACKGROUND/AIM: Successful therapy of EGFR-mutant NSCLC remains a challenging task despite initial benefits with the usage of EGFR tyrosine kinase inhibitors. Cancer immunotherapy has shown promising results in certain tumors, but response rate in EGFR-mutant NCLC is low, because these tumors are thought to have weak immunogenicity. MATERIALS AND METHODS: We used data from in vivo NSCLC databases as well as from in vitro cell culture experiments to investigate the regulation of CD73 by EGFR. RESULTS: EGFR expression was correlated with CD73 expression in patients' datasets, with EGFR-mutant tumors showing higher expression than their EGFR wildtype counterparts. Treatment of EGFR-mutant NSCLC cell lines with EGFR TKI reduced expression of CD73 at both mRNA and protein level. Among EGFR downstream signaling pathways, the Ras-Raf-ERK pathway was involved in the regulation of CD73 expression directly via ERK1/2 without the engagement of RSKs or MSKs. CONCLUSION: The results of this study may provide novel therapeutic strategies for the treatment of oncogene-driven NSCLC.

LIN-10 can promote LET-23 EGFR signaling and trafficking independently of LIN-2 and LIN-7.

During Caenorhabditis elegans larval development, an inductive signal mediated by the LET-23 EGFR (epidermal growth factor receptor), specifies three of six vulva precursor cells (VPCs) to adopt vulval cell fates. An evolutionarily conserved complex consisting of PDZ domain-containing scaffold proteins LIN-2 (CASK), LIN-7 (Lin7 or Veli), and LIN-10 (APBA1 or Mint1) (LIN-2/7/10) mediates basolateral LET-23 EGFR localization in the VPCs to permit signal transmission and development of the vulva. We recently found that the LIN-2/7/10 complex likely forms at Golgi ministacks; however, the mechanism through which the complex targets the receptor to the basolateral membrane remains unknown. Here we found that overexpression of LIN-10 or LIN-7 can compensate for loss of their complex components by promoting LET-23 EGFR signaling through previously unknown complex-independent and receptor-dependent pathways. In particular, LIN-10 can independently promote basolateral LET-23 EGFR localization, and its complex-independent function uniquely requires its PDZ domains that also regulate its localization to Golgi. These studies point to a novel complex-independent function for LIN-7 and LIN-10 that broadens our understanding of how this complex regulates targeted sorting of membrane proteins.

PARP-1 involves in UVB-induced inflammatory response in keratinocytes and skin injury via regulation of ROS-dependent EGFR transactivation and p38 signaling.

UV irradiation can injure the epidermis, resulting in sunburn, inflammation, and cutaneous tissue disorders. Previous studies demonstrate that EGFR in keratinocytes can be activated by UVB and contributes to inflammation. Poly (ADP-ribose) polymerase-1 (PARP-1) is a nuclear enzyme and plays an essential role in DNA repair under moderate stress. In this study, we set out to understand how PARP-1 regulates UVB irradiation-induced skin injury and interplays with EGFR to mediate the inflammation response. We found that PARP-1 deficiency exacerbated the UVB-induced inflammation, water loss, and back skin damage in mice. In human primary keratinocytes, UVB can activate PARP-1 and enhance DNA damage upon PARP-1 gene silencing. Moreover, PARP-1 silencing and PARP inhibitor olaparib can suppress UVB-induced COX-2 and MMP-1 expression, but enhance TNF-α and IL-8 expression. In addition, EGFR silencing or EGFR inhibition by gefitinib can decrease UVB-induced COX-2, TNF-α, and IL-8 expression, suggesting EGFR activation via paracrine action can mediate UVB-induced inflammation responses. Immunoblotting data revealed that PARP-1 inhibition decreases UVB-induced EGFR and p38 activation. Pharmacological inhibition of p38 also dramatically led to the attenuation of UVB-induced inflammatory gene expression. Of note, genetic ablation of PARP-1 or EGFR can attenuate UVB-induced ROS production, and antioxidant NAC can attenuate UVB-induced EGFR-p38 signaling axis and PARP-1 activation. These data suggest the regulatory loops among EGFR, PARP-1, and ROS upon UVB stress. PARP-1 not only serves DNA repair function but also orchestrates interactions to EGFR transactivation and ROS production, leading to p38 signaling for inflammatory gene expression in keratinocytes.

Antitumour immunity regulated by aberrant ERBB family signalling.

Aberrant signalling of ERBB family members plays an important role in tumorigenesis and in the escape from antitumour immunity in multiple malignancies. Molecular-targeted agents against these signalling pathways exhibit robust clinical efficacy, but patients inevitably experience acquired resistance to these molecular-targeted therapies. Although cancer immunotherapies, including immune checkpoint inhibitors (ICIs), have shown durable antitumour response in a subset of the treated patients in multiple cancer types, clinical efficacy is limited in cancers harbouring activating gene alterations of ERBB family members. In particular, ICI treatment of patients with non-small cell lung cancers with epidermal growth factor receptor (EGFR) alterations and breast cancers with HER2 alterations failed to show clinical benefits, suggesting that EGFR and HER2 signalling may have an essential role in inhibiting antitumour immune responses. Here, we discuss the mechanisms by which the signalling of ERBB family members affects not only autonomous cancer hallmarks, such as uncontrolled cell proliferation, but also antitumour immune responses in the tumour microenvironment and the potential application of immune-genome precision medicine into immunotherapy and molecular-targeted therapy focusing on the signalling of ERBB family members.

FHL1 promotes glioblastoma aggressiveness through regulating EGFR expression.

The four-and-a-half LIM domain protein 1 (FHL1) plays a key role in multiple cancers. Here, we characterized its role in glioblastoma (GBM), the most common and incurable form of brain cancer. Overexpression of FHL1 promotes growth, migration, and invasion of GBM cells in vivo and in vitro. In contrast, FHL1 silencing by RNAi exhibits the opposite effects. FHL1 interacts with the transcription factor SP1 to upregulate epidermal growth factor receptor (EGFR) expression and activate the downstream signaling cascades, including Src, Akt, Erk1/2, and Stat3, leading to GBM malignancy. FHL1 is highly expressed and positively correlated with EGFR levels in human GBM, particularly those of the classical subtype. Our results suggest that the FHL1-SP1-EGFR axis plays a tumor-promoting role, and highlight the translational potential of inhibiting FHL1 for GBM treatment.

Celecoxib and Afatinib synergistic enhance radiotherapy sensitivity on human non-small cell lung cancer A549 cells.

PURPOSE: Radioresistance is highly correlated with radiotherapy failure in clinical cancer treatment. In the current study, we sought to examine the efficacy of Celecoxib and Afatinib co-treatment as radiosensitizers in the management of non-small cell lung cancer (NSCLC) A549 cells. MATERIALS AND METHODS: Generally, A549 cells were cultured with the treatment of Celecoxib and/or Afatinib for 24 h. Then, the cells were exposed to irradiation at 2 Gy/min for 1 min. After the end of treatment, cell viability, clonogenic survival, apoptosis and Prostaglandin E2 (PGE2) Elisa assays were performed. Transcriptional levels of Cyclooxygenase-2 (COX-2) affected by Celecoxib and/or Afatinib were measured by RT-qPCR. Posttranscriptional level of epidermal growth factor receptor (EGFR)-related gene was measured by Western blotting analysis. RESULTS: Here, we, for the first time, reported that the co-treatment of Celecoxib and Afatinib regulates the resistance of NSCLC A549 cells to radiation. The co-treatment of Celecoxib and Afatinib sensitized radiotherapy through the radiation-induced loss of cell viability and colony formation, as well as apoptosis. Mechanistically, Celecoxib and Afatinib-treated cells showed the inhibition of COX-2 and EGFR expression, which may be responsible for the A549 cells' increased resistance to radiation. CONCLUSION: Our results suggested that Celecoxib and Afatinib regulate cell sensitivity to apoptosis, and thus modulate the resistance of NSCLC to radiation.

Loss of ACK1 Upregulates EGFR and Mediates Resistance to BRAF Inhibition.

Targeted BRAF(V600E) suppression by selective BRAF inhibitors (BRAFis; e.g., vemurafenib and dabrafenib) has led to a sea change in the treatment of metastatic melanoma. Despite frequent upfront responses, acquired resistance has compromised long-term applicability. Among the various mechanisms of resistance, activation of multiple receptor tyrosine kinases is a known critical factor that contributes to vemurafenib resistance⁠. EGFR activation has been recurrently identified in a set of vemurafenib-resistant melanomas, but little is known about how EGFR, or possibly other receptor tyrosine kinases, becomes activated. Here, we report that ACK1, a protein kinase that modulates EGFR turnover, is downregulated in vemurafenib-resistant melanoma cells. We also found that ACK1 depletion with short hairpin RNA decreased EGFR degradation when activated by epidermal growth factor, increased EGFR protein expression, and conferred resistance to BRAFis both in vitro and in vivo. Vemurafenib resistance mediated by ACK1 inhibition can be reversed by the EGFR inhibitor gefitinib. Our data indicate that ACK1 loss may be a post-transcriptional mechanism that increases EGFR signaling and contributes to drug resistance.

Selective inhibition of stemness through EGFR/FOXA2/SOX9 axis reduces pancreatic cancer metastasis.

Pancreatic cancer (PC) is difficult to defeat due to mechanism (s) driving metastasis and drug resistance. Cancer stemness is a major challenging phenomenon associated with PC metastasis and limiting therapy efficacy. In this study, we evaluated the pre-clinical and clinical significance of eradicating pancreatic cancer stem cells (PCSC) and its components using a pan-EGFR inhibitor afatinib in combination with gemcitabine. Afatinib in combination with gemcitabine significantly reduced KrasG12D/+; Pdx-1 Cre (KC) (P < 0.01) and KrasG12D/+; p53R172H/+; Pdx-1 Cre (KPC) (P < 0.05) derived mouse tumoroids and KPC-derived murine syngeneic cell line growth compared to gemcitabine/afatinib alone treatment. The drug combination also reduced PC xenograft tumor burden (P < 0.05) and the incidence of metastasis by affecting key stemness markers, as confirmed by co-localization studies. Moreover, the drug combination significantly decreases the growth of various PC patient-derived organoids (P < 0.001). We found that SOX9 is significantly overexpressed in high-grade PC tumors (P < 0.05) and in chemotherapy-treated patients compared to chemo-naïve patients (P < 0.05). These results were further validated using publicly available datasets. Moreover, afatinib alone or in combination with gemcitabine decreased stemness and tumorspheres by reducing phosphorylation of EGFR family proteins, ERK, FAK, and CSC markers. Mechanistically, afatinib treatment decreased CSC markers by downregulating SOX9 via FOXA2. Indeed, EGFR and FOXA2 depletion reduced SOX9 expression in PCSCs. Taken together, pan-EGFR inhibition by afatinib impedes PCSCs growth and metastasis via the EGFR/ERK/FOXA2/SOX9 axis. This novel mechanism of pan-EGFR inhibitor and its ability to eradicate CSC may serve as a tailor-made approach to enhance chemotherapeutic benefits in other cancer types.

Synergistic effect between LH and estrogen in the acceleration of cumulus expansion via GPR30 and EGFR pathways.

The estrogen membrane receptor GPR30 (also known as G-protein coupled receptor 30) has recently been shown to be involved in the regulation of oocyte maturation and cumulus expansion. However, whether GPR30 expression is regulated by gonadotropin stimulation and how it participates in the regulation of the maturation process is still not clear. In this study, we explored the mechanism underlying the synergy between luteinizing hormone and 17ß-estradiol (17ß-E2) to improve the epidermal growth factor (EGF) response in cumulus oocyte complexes (COCs) during oocyte maturation in mice. The expression and distribution of GPR30, EGFR, and EGF-like growth factors were examined by real-time quantitative PCR, western blot, and immunofluorescence staining. Lyso-Tracker Red labeling was performed to detect the lysosomal activity in follicle granular cells (FGCs). Cumulus expansion of COCs was evaluated after in vitro maturation for 16 h. We found that EGF-like growth factors transmit LH signals to increase GRP30 levels by inhibiting protein degradation in lysosomes. Meanwhile, 17ß-E2 stimulates the GPR30 signaling pathway to increase EGF receptor levels, enhancing the response ability of EGF signaling in COCs and thus promoting cumulus expansion. In conclusion, our study reveals the synergistic mechanism between LH and estrogen in the regulation of cumulus expansion during oocyte maturation process.

Combined EGFR1 and PARP1 Inhibition Enhances the Effect of Radiation in Head and Neck Squamous Cell Carcinoma Models.

Head and neck squamous cell carcinoma (HNSCC) is a challenging cancer with little change in five-year overall survival rate of 50-60% over the last two decades. Radiation with or without platinum-based drugs remains the standard of care despite limited benefit and high toxicity. HNSCCs often overexpress epidermal growth factor receptor (EGFR) and inhibition of EGFR signaling enhances radiation sensitivity by interfering with repair of radiation-induced DNA breaks. Poly (adenosine diphosphate-ribose) polymerase-1 (PARP1) also participates in DNA damage repair, but its inhibition provides benefit in cancers that lack DNA repair by homologous recombination (HR) such as BRCA-mutant breast cancer. HNSCCs in contrast are typically BRCA wild-type and proficient in HR repair, making it challenging to apply anti-PARP1 therapy in this model. A recently published study showed that a combination of EGFR and PARP1 inhibition induced more DNA damage and greater growth control than each single agent in HNSCC cells. This led us to hypothesize that a combination of EGFR and PARP1 inhibition would enhance the efficacy of radiation to a greater extent than each single agent, providing a rationale for paradigm-shifting combinatorial approaches to improve the standard of care in HNSCC. Here, we report a proof-of-concept study using Detroit562 HNSCC cells, which are proficient for DNA repair by both HR and non-homologous end joining (NHEJ) mechanisms. We tested the effect of adding cetuximab and/or olaparib (inhibitors of EGFR and PARP1, respectively) to radiation and compared it to that of cisplatin and radiation combination, which is the standard of care. Our results demonstrate that the combination of cetuximab and olaparib with radiation was superior to the combination of any single drug with radiation in terms of induction of unrepaired DNA damage, induction of senescence, apoptosis and clonogenic death, and tumor growth control in mouse xenografts. Combined with our recently published phase I safety data on cetuximab/olaparib/radiation triple combination, the data reported here demonstrate a potential for combining biologically-based therapies that might optimize radiosensitization in HNSCC.

EGFR in enterocytes & endothelium and HIF1α in enterocytes are dispensable for massive small bowel resection induced angiogenesis.

BACKGROUND: Short bowel syndrome (SBS) results from significant loss of small intestinal length. In response to this loss, adaptation occurs, with Epidermal Growth Factor Receptor (EGFR) being a key driver. Besides enhanced enterocyte proliferation, we have revealed that adaptation is associated with angiogenesis. Further, we have found that small bowel resection (SBR) is associated with diminished oxygen delivery and elevated levels of hypoxia-inducible factor 1-alpha (HIF1α). METHODS: We ablated EGFR in the epithelium and endothelium as well as HIF1α in the epithelium, ostensibly the most hypoxic element. Using these mice, we determined the effects of these genetic manipulations on intestinal blood flow after SBR using photoacoustic microscopy (PAM), intestinal adaptation and angiogenic responses. Then, given that endothelial cells require a stromal support cell for efficient vascularization, we ablated EGFR expression in intestinal subepithelial myofibroblasts (ISEMFs) to determine its effects on angiogenesis in a microfluidic model of human small intestine. RESULTS: Despite immediate increased demand in oxygen extraction fraction measured by PAM in all mouse lines, were no differences in enterocyte and endothelial cell EGFR knockouts or enterocyte HIF1α knockouts by POD3. Submucosal capillary density was also unchanged by POD7 in all mouse lines. Additionally, EGFR silencing in ISEMFs did not impact vascular network development in a microfluidic device of human small intestine. CONCLUSIONS: Overall, despite the importance of EGFR in facilitating intestinal adaptation after SBR, it had no impact on angiogenesis in three cell types-enterocytes, endothelial cells, and ISEMFs. Epithelial ablation of HIF1α also had no impact on angiogenesis in the setting of SBS.