Epidermal Growth Factor Receptor Kinase Activity Research Articles

Identification of a patient tissue-based phosphorylation site as a biomarker for epidermal growth factor receptor (EGFR) activity in non-small cell lung cancer.

3143 Background: Non-small cell lung cancer (NSCLC) is a leading cause of cancer-related deaths globally. EGFR tyrosine kinase inhibitors (TKIs) have shown promise in treating NSCLC, yet resistance to these agents is common and current biomarkers rely on genetic data alone. Therefore, identifying reliable biomarkers to more comprehensively monitor EGFR activity and predict therapeutic responses is paramount. Here, we report an uncharacterized threonine phosphorylation site within core regulator of the EGFR pathway SHP2, that is strongly predictive of EGFR activity as defined by genetic mutation status that shows potential as a clinically relevant biomarker. Methods: Using DIA mass spectrometry phosphoproteomics, we could quantify >20,000 phosphosites from patient normal adjacent tumor (NAT) and primary tumor tissue. We further characterized these tissues using whole genome sequencing allowing us to define the mutational status of the EGFR. Statistical analysis was undertaken across all phospho-sites that identified a single uncharacterized phospho-site as a strong predictor of EGFR kinase activity. Finally, we generated monoclonal antibodies against the phospho-peptide and tested these in patient FFPE primary tumor tissue using immunohistochemistry to correlate phosphorylation levels with EGFR activation status. Results: Our results highlight how an individual phosphosite on SHP2 closely correlates with EGFR activity as defined by genetic mutation status in patient tissue. Interestingly, we further identify a group of patients who carry wild type EGFR yet have a phospho-signal potentially indicative of high EGFR activation without genetic aberration. These results were corroborated by a phospho-site specific antibody in FFPE tissue IHC, with strong signals observed in patients with an activating EGFR mutation (n=5), and complete absence of signal in patients harboring a wild type EGFR and no detectable mass spec signal (n=5). Conclusions: Our findings suggest that this uncharacterised SHP2 phosphosite may serve as a potent biomarker for EGFR activity in NSCLC. Further validation of the monoclonal antibodies as tools for this clinically relevant biomarker is required in larger patient cohorts to elucidate the role of the phosphosite in therapy response. This novel biomarker has the potential to guide therapeutic decision-making and contribute to personalized medicine strategies for NSCLC patients.

Structural determinants for membrane binding of the EGFR juxtamembrane domain.

Overactivation of the epidermal growth factor receptor (EGFR) is critical for the development of multiple cancers. Previous studies have shown that the cell membrane is a key regulator of EGFR kinase activity through its interaction with the EGFR juxtamembrane domain (JM). However, the lipid recognition specificity of EGFR-JM and its interaction details remain unclear. Using lipid strip and liposome pulldown assays, we showed that EGFR-JM could specifically interact with PI(4,5)P2-or phosphatidylserine-containing membranes. We further characterized the JM-membrane interaction using NMR-titration-based chemical shift perturbation and paramagnetic relaxation enhancement analyses, and found that residues I649 - L659 comprised the membrane-binding site. Furthermore, the membrane-binding region contains the predicted dimerization motif of JM, 655LRRLL659, suggesting that membrane binding may affect JM dimerization and, therefore, regulate kinase activation.

DRD1 suppresses cell proliferation and reduces EGFR activation and PD-L1 expression in NSCLC.

Dopamine (DA) acts in various key neurological and physiological processes as both a neurotransmitter and circulating hormone. Over the past several decades, the DA signaling network has been shown to regulate the progression of several types of solid tumors, and considerable evidence has shown it is a druggable pathway in the cancer cell context. However, the specific activity and effect of these pathway components appears to be tissue-type and cell-context-dependent. In the present study, expression and methylation of dopamine receptor D1 (DRD1) were measured using RNA sequencing (RNAseq) and reverse transcription polymerase chain reaction (RT-PCR) in non-small cell lung cancer (NSCLC) samples, and validated using publicly available datasets, including The Cancer Genome Atlas (TCGA). In vitro and in vivo functional experiments were performed for cell proliferation and tumor growth, respectively. Mechanistic analyses of the transcriptome and kinome in DRD1-modulated cells informed further experiments, which characterized the effects on the epidermal growth factor receptor (EGFR) pathway and programmed cell death 1 ligand 1 (PD-L1) proteins. Through these experiments, we identified the DRD1 gene as a negative regulator of disease progression in NSCLC. We show that DRD1, as well as other DA pathway components, are expressed in normal human lung tissue, and that loss of DRD1 expression through promoter hypermethylation is a common feature in NSCLC patients and is associated with worse survival. At the cellular level, DRD1 affects proliferation by inhibiting the activation of EGFR and mitogen-activated protein kinase 1/2 (ERK1/2). Interestingly, we also found that DRD1 regulates the expression of PD-L1 in lung cancer cells. Taken together, these results suggest that DRD1 methylation may constitute a biomarker of poor prognosis in NSCLC patients while other components of this pathway could be targeted to improve response to EGFR- and PD-L1-targeted therapies.

Computational insights into the stereo-selectivity of catechins for the inhibition of the cancer therapeutic target EGFR kinase.

The epidermal growth factor receptor (EGFR) plays a crucial role in regulating cellular growth and survival, and its dysregulation is implicated in various cancers, making it a prime target for cancer therapy. Natural compounds known as catechins have garnered attention as promising anticancer agents. These compounds exert their anticancer effects through diverse mechanisms, primarily by inhibiting receptor tyrosine kinases (RTKs), a protein family that includes the notable member EGFR. Catechins, characterized by two chiral centers and stereoisomerism, demonstrate variations in chemical and physical properties due to differences in the spatial orientation of atoms. Although previous studies have explored the membrane fluidity effects and transport across cellular membranes, the stereo-selectivity of catechins concerning EGFR kinase inhibition remains unexplored. In this study, we investigated the stereo-selectivity of catechins in inhibiting EGFR kinase, both in its wild-type and in the prevalent L858R mutant. Computational analyses indicated that all stereoisomers, including the extensively studied catechin (-)-EGCG, effectively bound within the ATP-binding site, potentially inhibiting EGFR kinase activity. Notably, gallated catechins emerged as superior EGFR inhibitors to their non-gallated counterparts, revealing intriguing binding trends. The top four stereoisomers exhibiting high dock scores and binding energies with wild-type EGFR comprise (-)-CG (-)-GCG (+)-CG, and (-)-EGCG. To assess dynamic behavior and stability, molecular dynamics simulations over 100 ns were conducted for the top-ranked catechin (-)-CG and the widely investigated catechin (-)-EGCG with EGFR kinase. This study enhances our understanding of how the stereoisomeric nature of a drug influences inhibitory potential, providing insights that could guide the selection of specific stereoisomers for improved efficacy inexisting drugs.

Structure and activity relationship analysis of xanthones from mangosteen: Identifying garcinone E as a potent dual EGFR and VEGFR2 inhibitor.

Xanthones are among the most fundamental phytochemicals in nature. The anti-cancer activities of xanthones and their derivatives have been extensively studied. Recently, we found that garcinone E (GE), an effective anti-cancer phytochemical isolated from mangosteen (Garcinia mangostanal.), showed promising anti-cancer effects in vitro and in vivo. However, little is known about its effects on epidermal growth factor receptor (EGFR) and vascular endothelial growth factor receptor 2 (VEGFR2) activity. This study aimed to identify potent dual EGFR and VEGFR2 inhibitors from mangosteen-derived xanthones using structure-activity relationship analyses. The interaction of xanthones with EGFR and VEGFR2 was analyzed using molecular docking experiments. The kinase activities of EGFR and VEGFR2 were determined using bioluminescence assays. The rat aortic ring and Matrigel plug angiogenesis assays were used to evaluate blood vessel formation ex vivo and in vivo. A breast tumor-bearing nude mouse model was established to examine the anti-tumor effects of different xanthones. Molecular docking analysis showed that GE bound tightly to EGFR and VEGFR2, with binding energies of -9.73 and -9.56kcal/mol, respectively. Kinase activity assessment showed that GE strongly inhibited both EGFR and VEGFR2 kinase activity, with IC50 values of 315.4 and 158.2nM, respectively. Moreover, GE significantly abolished the EGF- and VEGF-induced phosphorylation of EGFR and VEGFR2, respectively. GE also showed strong inhibitory effects on cancer cell growth, endothelial cell migration, invasion, and tube formation. Ex vivo and in vivo angiogenesis assays showed that GE dose-dependently suppressed blood vessel formation in the rat aorta, Matrigel plugs, and transgenic zebrafish embryos, with the lowest effective concentration of 0.25μM. Furthermore, GE (2mg/kg) strongly inhibited tumor growth and reduced tumor weight in MDA-MB-231 breast tumor-xenografted mice. GE significantly reduced microvessel density and downregulated the expression of VEGFR2, EGFR, and Ki67 in tumor tissues. The present study demonstrated that GE was the most potent dual inhibitor of EGFR and VEGFR2 among all xanthones tested. These findings may provide valuable information for the future development of novel and effective dual inhibitors of EGFR and VEGFR2.

Synthesis, photophysical properties, anticancer evaluation, and molecular docking studies of new pyrimidine linked 4-arylidene-thiazolidin-4-ones as potent anticancer agents.

The reaction of 4-(chloroacetamido)pyrimidine (1) with ammonium thiocyanate gave 2-(pyrimidin-4-ylimino)thiazolidin-4-one (2), which, when condensed with four substituted benzaldehyde analogues, gave the consequent 5-arylidine-2-(pyrimidin-4-ylimino)thiazolidin-4-ones 3a-d. In addition, the absorbance and fluorescence behaviours of pyrimidinylimino-thiazolidin-4-one hybrids 3a-d in various organic solvents were investigated. The emphasis was on studying UV absorption capacities and the effect of various structural components on photophysical qualities such as the 5-arylidene-2-(pyrimidin-4-ylimino)thiazolidin-4-ones and N,N-dimethylamino tail. The cytotoxic effect of four pyrimidinylimino-thiazolidin-4-one hybrids 3a-d on tumour cell lines (HepG2, HCT-116, PC3, MCF-7) and a normal cell line (WI38) is investigated in this work. The cytotoxicity was measured by comparing the half-maximal inhibitory concentration (IC50 ) to the reference medication, 5-fluorouracil. The findings indicate that these hybrid compounds had varying cytotoxic effects on the cell lines examined; hybrids 3b and 3c demonstrated significant anticancer activity against MCF-7 with IC50 values of 7.53 ±0.43 and 9.17 ±0.31 μM, respectively. The inhibitory efficacy of various synthesized hybrids on the epidermal growth factor receptor (EGFR) kinase was investigated. EGFR is a crucial target in cancer treatment because inhibiting it may reduce tumour development and proliferation. The IC50 value was used to calculate the inhibitory activity, which is the concentration of inhibitor necessary to induce half-maximal inhibition of EGFR kinase activity. In addition, the predicted ADME results show that pyrimidinylimino-thiazolidin-4-one hybrids have good pharmacokinetic properties; hybrid 3d is more lipophilic than the other compounds. It has a medium molecular weight, a small number of hydrogen bond acceptors and donors, and a large number of aromatic heavy atoms. Moreover, molecular docking simulations revealed precise information on the interactions of pyrimidinylimino-thiazolidin-4-one hybrids 3a-d and 5-Fu with their respective protein targets. These interactions point to possible pathways for their biological activities and call for more testing to establish their effectiveness as bioactive molecules or therapeutic candidates.

Efficacy of HMJ-38, a new quinazolinone analogue, against the gemcitabine-resistant MIA-PaCa-2 pancreatic cancer cells.

Gemcitabine is frequently utilized to treat pancreatic cancer. The purpose of our study was to create a gemcitabine-resistant MIA-PaCa-2 pancreatic cancer cell line (MIA-GR100) and to evaluate the anti-pancreatic cancer efficacy of HMJ-38, a new quinazolinone analogue. Compared to their parental counterparts, MIA-PaCa-2, established MIA-GR100 cells were less sensitive to gemcitabine. MIA-GR100 cell viability was not affected by 10, 50 and 100 nM gemcitabine concentrations. HMJ-38 reduced MIA-GR100 cell growth and induced autophagy and apoptosis. When stained with monodansylcadaverine (MDC), acridine orange (AO), and terminal deoxynucleotide transferase dUTP nick end labeling (TUNEL), MIA-GR100 cells shrunk, punctured their membranes, and produced autophagy vacuoles and apoptotic bodies. Combining chloroquine (CQ) and 3-methyladenine (3-MA) with HMJ-38 dramatically reduced cell viability, indicating that autophagy function as a cytoprotective mechanism. MIA-GR100 cells treated with both z-VAD-FMK and HMJ-38 were much more viable than those treated with HMJ-38 alone. HMJ-38 promotes apoptosis in MIA-GR100 cells by activating caspases. Epidermal growth factor receptor (EGFR) is one of HMJ-38's principal targets, as determined via in silico target screening with network prediction. HMJ-38 also inhibited EGFR kinase activity and EGFR-associated signaling in MIA-GR100 cells. HMJ-38 may be an effective chemotherapeutic adjuvant for gemcitabine-resistant pancreatic cancer cells, in which it induces an antitumor response.

EGFR suppression contributes to growth inhibitory activity of G-quadruplex ligands in non-small cell lung cancers

Non-small cell lung carcinomas (NSCLCs) commonly harbor activating mutations in the epidermal growth factor receptor (EGFR). Drugs targeting the tyrosine kinase activity of EGFR have shown effectiveness in inhibiting the growth of cancer cells with EGFR mutations. However, the development of additional mutations in cancer cells often leads to the persistence of the disease, necessitating alternative strategies to overcome this challenge. We explored the efficacy of stabilizing the G-quadruplex structure formed in the promoter region of EGFR as a means to suppress its expression and impede the growth of cancer cells with EGFR mutations. We revealed that the carbazole derivative BMVC-8C3O effectively suppressed EGFR expression and demonstrated significant growth inhibition in EGFR-mutated NSCLC cells, both in cell culture and mouse xenograft models. Importantly, the observed repression of EGFR expression and growth inhibition were not exclusive to carbazole derivatives, as several other G-quadruplex ligands exhibited similar effects. The growth-inhibitory activity of BMVC-8C3O is attributed, at least in part, to the repression of EGFR, although it is possible that additional cellular targets are also affected. Remarkably, the growth-inhibitory effect was observed even in osimertinib-resistant cells, indicating that BMVC-8C3O holds promise for treating drug-resistant NSCLC. Our findings present a promising and innovative approach for inhibiting the growth of NSCLC cells with EGFR mutations by effectively suppressing EGFR expression. The demonstrated efficacy of G-quadruplex ligands in this study highlights their potential as candidates for further development in NSCLC therapy.

Coupled folding-upon-binding of human tumor suppressor MIG6 to lung cancer EGFR kinase domain and molecular trimming/stapling of MIG6-derived β-hairpins to target the coupling event.

Human epidermal growth factor receptor (EGFR) is involved in strong association with malignant proliferation, which has been shown to play a central role in the development and progression of non-small cell lung cancer and other solid tumors. The tumor-suppressor protein MIG6 is a negative regulator of EGFR kinase activity by binding at the activation interface of asymmetric dimer of EGFR kinase domain to disrupt EGFR dimerization and then inactivate the kinase. The protein adopts two discrete fragments 1 and 2 to directly interact with EGFR. It is revealed that the MIG6 fragment 2 is intrinsically disordered in free unbound state, but would fold into a well-structured β-hairpin when binding to EGFR, thus characterized by a so-called coupled folding-upon-binding process, which can be regarded as a compromise between favorable direct readout and unfavorable indirect readout. Here, a 23-mer F2P peptide was derived from MIG6 fragment 2, trimmed into a 17-mer tF2P peptide that contains the binding hotspot region of the fragment 2, and then constrained with an ordered hairpin conformation in free unbound state by disulfide stapling, finally resulting in a rationally stapled/trimmed stF2P peptide that largely minimizes the unfavorable indirect readout effect upon its binding to EGFR kinase domain, with affinity improved considerably upon the trimming and stapling/trimming. These rationally designed β-hairpin peptides may be further exploited as potent anti-lung cancer agents to target the activation event of EGFR dimerization.

Dephosphorylation of the EGFR protein by calcineurin at serine 1046/1047 enhances its stability

The epidermal growth factor receptor (EGFR) is highly expressed or abnormally activated in several types of cancers, such as lung and colorectal cancers. Inhibitors that suppress the tyrosine kinase activity of EGFR have been used in the treatment of lung cancer. However, resistance to these inhibitors has become an issue in cancer treatment, and the development of new therapies that inhibit EGFR is desired. We found that calcineurin, a Ca2+/calmodulin-activated serine/threonine phosphatase, is a novel regulator of EGFR. Inhibition of calcineurin by FK506 treatment or calcineurin depletion promoted EGFR degradation in cancer cells. In addition, we found that calcineurin dephosphorylates EGFR at serine (S)1046/1047, which in turn stabilizes EGFR. Furthermore, in human colon cancer cells transplanted into mice, the inhibition of calcineurin by FK506 decreased EGFR expression. These results indicate that calcineurin stabilizes EGFR by dephosphorylating S1046/1047 and promotes tumor growth. These findings suggest that calcineurin may be a new therapeutic target for cancers with high EGFR expression or activation.

Epidermal Growth Factor Receptor Kinase Inhibitor Ameliorates β-Amyloid Oligomer-Induced Alzheimer Disease in Swiss Albino Mice.

Alzheimer’s disease (AD) is one of the major neurodegenerative disorders, and its incidence increases globally every year. Currently, available AD drugs symptomatically treat AD with multiple adverse effects. Gefitinib (GE) is an epidermal growth factor receptor (EGFR) kinase inhibitor. EGFR is the preferred target for the treatment of AD, whereas the effect of GE in AD conditions is limited. The present study was designed to explore the ameliorative potential of GE in Aβ1–42 oligomer-induced neurotoxicity in AD mice. AD was induced by intracerebroventricular (i.c.v.) injection of Aβ1–42 oligomer (4 μg/4 μL) into the lateral ventricles of the mouse brain. The test compound, i.e., GE (2 and 4 mg/kg of body weight), was administered orally on days 10, 13, 16, 19, 22, 25, and 28, and the reference drug, i.e., donepezil (DP, 2 mg/kg), was administered orally from the 10th to 28th days. The behavioral changes were screened by the Morris water maze (MWM) test. Furthermore, biomarkers i.e., brain acetylcholinesterase (AChE), thiobarbituric acid reactive substances (TBARS), and reduced glutathione (GSH) levels were estimated from brain samples. The AD-associated histopathological changes were analyzed by hematoxylin and eosin staining. The administration of GE significantly ameliorated the AD-associated behavioral, biochemical, and histopathological changes. The ameliorative effect of GE against the Aβ1–42 oligomer-associated neurotoxicity was due to its potent inhibition of EGFR kinase activation, as well as its antioxidant and antilipid peroxidative effect.

Phosphorylated STYK1 restrains the inhibitory role of EGFR in autophagy initiation and EGFR-TKIs sensitivity.

Epidermal growth factor receptor (EGFR) plays critical roles in cell proliferation and tumorigenesis. Autophagy has emerged as a potential mechanism involved in the acquired resistance to anti-EGFR treatments, however, the molecular mechanisms has not been fully addressed. In this study, we identified EGFR interacts with STYK1, a positive autophagy regulator, in EGFR kinase activity dependent manner. We found that EGFR phosphorylates STYK1 at Y356 site and STYK1 inhibits activated EGFR mediated Beclin1 tyrosine phosphorylation and interaction between Bcl2 and Beclin1, thus enhances PtdIns3K-C1 complex assembly and autophagy initiation. We also demonstrated that STYK1 depletion increased the sensitivity of NSCLC cells to EGFR-TKIs in vitro and in vivo. Moreover, EGFR-TKIs induced activation of AMPK phosphorylates STYK1 at S304 site. STYK1 S304 collaborated with Y356 phosphorylation to enhance the EGFR-STYK1 interaction and reverse the inhibitory effects of EGFR to autophagy flux. Collectively, these data revealed new roles and cross-talk between STYK1 and EGFR in autophagy regulation and EGFR-TKIs sensitivity in NSCLC.

Expanded Application of a Photoaffinity Probe to Study Epidermal Growth Factor Receptor Tyrosine Kinase with Functional Activity.

The abnormal activation of the epidermal growth factor receptor (EGFR) is strongly associated with cancer invasion and metastasis. Tools and methods are required to study and visualize EGFR activation under (patho)physiological conditions. Here, we report the development of a two-step photoaffinity probe (HX101) by incorporation of a diazirine as a photoreactive group and an alkyne as a ligation handle to quantitively study EGFR kinase activity in native cellular contexts and human tissue slices. HX101 is a multifunctional probe based on the pharmacophore of the EGFR tyrosine kinase inhibitor (EGFR-TKI) and can covalently target the EGFR upon photoactivation. The incorporated alkyne serves as a versatile ligation handle and enables HX101 to introduce distinct reporter groups (e.g., fluorophore and biotin) via click chemistry. With variable reporter tags, HX101 enables visualization and target engagement studies of the active EGFR in a panel of cancer cells using flow cytometry, confocal microscopy, and mass spectrometry. Furthermore, as a proof of concept study, we applied HX101 in stochastic optical reconstruction microscopy super-resolution imaging to study EGFR activation in live cells. Importantly, HX101 was also applied to visualize EGFR mutant activity in tumor tissues from lung cancer patients for prediction of EGFR-TKI sensitivity. Altogether, our results demonstrate the wide application of a selective photoaffinity probe in multi-modal assessment/visualization of EGFR activity in both live cells and tissue slices. We anticipate that these diverse applications can facilitate the translation of a strategically functionalized probe into medical use.

Psorachromene induces apoptosis and suppresses tumor growth in NSCLC cells harboring EGFR L858R/T790M/C797S.

The extracts from Psoralea corylifolia Linn. (P. corylifolia) seeds have been shown to display antitumor activity. To date, the prospects of this plant and its active compounds in the treatment of non-small-cell lung cancer (NSCLC) have not been thoroughly studied. In this study, we identified a novel psorachromene compound that displays selective cytotoxic effects on all NSCLC cells tested, including NSCLC cells harboring epidermal growth factor receptor (EGFR) activation mutants (H1975L858R/T790M and H1975-MS35L858R/T790M/C797S ). Psorachromene induces G1 arrest in NSCLC cells harboring wild-type EGFR but induces apoptosis in NSCLC cells harboring activating EGFR mutations. Psorachromene inhibits activated EGFR signaling and kinase activity and suppresses tumor growth of implanted H1975-MS35L858R/T790M/C797S cells in nude mice. Molecular docking analysis revealed that psorachromene could form stronger bonds with mutant EGFR than wild-type EGFR, which might account for the greater cytotoxic effects observed in NSCLC cells harboring activating EGFR mutations (H1975 and H1975-MS35) than wild-type EGFR (A549). In conclusion, it is suggested that psorachromene is an attractive agent to be further explored for its use in the treatment of NSCLC patients harboring EGFR L858R/T790M/C797S.

The Antibiotic and Antiprotozoal Agent Dibromopropamidine Dihydrochloride is a New EGFR Inhibitor and Potential Anticancer Drug for Bladder Cancer

AbstractThe epidermal growth factor receptor (EGFR) is a promising therapeutic target in bladder cancer (BC). Thus, the development of novel EGFR inhibitor is urgently needed. We computationally screened 3,167 worldwide approved small molecule drugs for potential wild‐type EGFR inhibitors. The antibiotic and antiprotozoal agent dibromopropamidine dihydrochloride exhibited the highest cytotoxic activity in a dose‐ and time‐dependent manner, with the IC50 similar to that reported for the FDA approved EGFR inhibitors, gefitinib and higher than afatinib. We demonstrated that dibromopropamidine dihydrochloride inhibited the wild type EGFR kinase activity while had no effect on HER‐2 kinase activity. Furthermore, dibromopropamidine dihydrochloride treatment significantly promoted cell apoptosis and inhibited the phosphorylation of EGFR and its downstream proteins AKT and ERK in a dose‐dependent manner. Structural analysis of the predicted binding conformation suggested that dibromopropamidine dihydrochloride binds to EGFR at ATP binding site via the formation of two hydrogen bonds with GLY796 and ASP855. Finally, dibromopropamidine dihydrochloride significantly suppressed tumor growth in vivo. These results suggest for the first time that dibromopropamidine dihydrochloride is an EGFR inhibitor, and a promising anticancer candidate drug for the treatment of BC.

Design, synthesis, and molecular modeling of quinoline-based derivatives as anti-breast cancer agents targeting EGFR/AKT signaling pathway.

Two series of quinoline-thiazole and quinoline-thiazolidinone hybrids were designed, synthesized, and evaluated for their in vitro antitumor activity on MCF-7 breast cancer cell line. In comparison with lapatinib (IC50 =4.69µM), compounds 4b and 6b exhibited the best antiproliferative activity with IC50 values of 33.19 and 5.35µM, respectively. Although compound 6b showed higher cytotoxicity, compound 4b exhibited better inhibitory activity toward the epidermal growth factor receptor (EGFR) pathway than compound 6b as represented by the significant reduction in the EGFR kinase activity and the levels of phosho-EGFR and phosho-AKT when compared to lapatinib as a reference standard. Moreover, compound 4b was capable of down-regulating the anti-apoptotic genes Bcl-2 and survivin and up-regulating the level of the pro-apoptotic gene BAX. Molecular modeling study was carried out to predict the binding interactions of both compounds into the target kinase. Finally, the physicochemical properties were investigated in silico as well.

Caroli disease: an update on pathogenesis.

Caroli disease: an update on pathogenesis.

A novel cyclic NP1 reveals obstructionof EGFR kinase activity and attenuation of EGFR-driven cell lines.

Aberrations of the epidermal growth factor receptor (EGFR), for example, mutations and overexpression, play pivotal roles in various cellular functions, such as proliferation, migration, and cell differentiation. Approved small molecule-based inhibitors, including gefitinib and erlotinib, are used clinically to target the tyrosine kinase domain of EGFR (TK-EGFR). However, the severity of the side effects, off-target effects, and drug resistance is a concern. Cyclic peptides are a well-known peptide format with high stability and are promising molecules for drug development. Herein, the Ph.D.™-C7C phage display library was used to screen cyclic peptides against TK-EGFR. Biopanning, both with and without propagation methods, was performed to assess the highest capacity peptides using the enzymatic activity of TK-EGFR. Interestingly, NP1, a peptide selected during biopanning without propagation demonstrated an inhibitory effect against TK-EGFR at IC50 within the nanomolar range; this effect was better than that of P1 obtained using biopanning with propagation. Moreover, NP1 elicited EGFR with an affinity binding (KD ) value of 18.40 ± 5.50 µM by surface plasmon resonance (SPR). Introducing cell-penetrating peptides or Arginine-9 (Arg9) at the N-terminus of NP1 thus improves cell-penetrability and can lead to the inhibition of EGFR-driven cancer cell lines; however, it exhibits no hepatotoxicity. Furthermore, NP1 caused a decrease in phosphorylated EGFR after activation within cells. A docking model shows that NP1 interacted primarily with TK-EGFR via hydrogen bonding. Together, this suggests that NP1 is a novel EGFR peptide inhibitor candidate with specificity and selectivity toward TK-EGFR, and may be applied to targeted therapy.

Disabled 1 Is Part of a Signaling Pathway Activated by Epidermal Growth Factor Receptor.

Disabled 1 (Dab1) is an adapter protein for very low density lipoprotein receptor (VLDLR) and apolipoprotein E receptor 2 (ApoER2) and an integral component of the Reelin pathway which orchestrates neuronal layering during embryonic brain development. Activation of Dab1 is induced by binding of Reelin to ApoER2 and VLDLR and phosphorylation of Dab1 mediated by Src family kinases. Here we show that Dab1 also acts as an adaptor for epidermal growth factor receptor (EGFR) and can be phosphorylated by epidermal growth factor (EGF) binding to EGFR. Phosphorylation of Dab1 depends on the kinase activity of EGFR constituting a signal pathway independent of Reelin and its receptors.

Cross-Talk between STYK1 and EGFR in Autophagy Regulation and EGFR-TKIs Sensitivity in Non-Small Cell Lung Cancer

Epidermal growth factor receptor (EGFR) plays critical roles in cell proliferation and tumorigenesis. Autophagy has emerged as a potential mechanism involved in the acquired resistance to anti-EGFR treatments, however, the molecular mechanisms has not been fully addressed. In this study, we identified EGFR interacts with STYK1, a positive autophagy regulator, in EGFR kinase activity dependent manner. We also found that EGFR phosphorylates STYK1 at Y356 site and STYK1 inhibits activated EGFR mediated Beclin1 tyrosine phosphorylation and interaction between Bcl2 and Beclin1, thus enhances PtdIns3K-C1 complex assembly and autophagy initiation. We also demonstrated that STYK1 depletion increased the sensitivity of NSCLC cells to EGFR-TKIs in vitro and in vivo. Moreover, EGFR-TKIs induced activation of AMPK phosphorylates STYK1 at S304 site. STYK1 S304 collaborated with Y356 phosphorylation to enhance the EGFR-STYK1 interaction and reverse the inhibitory effects of EGFR to autophagy flux. Collectively, these data revealed new roles and cross-talk between STYK1 and EGFR in autophagy regulation and EGFR-TKIs sensitivity in NSCLC.