Clinical implications of EGFR expression in the development and progression of solid tumors: focus on non-small cell lung cancer

The Prognostic Impact of Epidermal Growth Factor Receptor (EGFR) in Patients with Acute Myeloid Leukaemia

Expression of Epidermal Growth Factor Receptor (EGFR), an important proto-oncogene, regulates cell differentiation, proliferation, cell migration and survival in most of the cancer types. EGFR expression has been reported in Acute Myeloid Leukaemia (AML), however, many other reports nullified EGFR expression in AML. These contradictory data prompted us to reevaluate the expression of EGFR in AML and carry out a comparative survival analysis between EGFR expressing and non-expressing AML patients (Children and Acute Promyelocytic Leukaemia patients excluded). Bone marrow and/or peripheral blood samples were collected from 60 adult patients with AML with written informed consent. PCR, Real-Time Taqman gene expression assays were used for the detection of genetic alterations. Statistical analysis was conducted using SPSS software (IBM SPSS 20). In our study, EGFR expression was detected in 21 out of 60, in 35% (95% C.I. 23.45-48.48) AML patients. Overall survival was significantly shorter in patients with EGFR (p = < 0.01), with an average survival of 18.57 months (95% C.I. 12.42-24.73 months) compared with 31.27 months (95% C.I. 28.19-34.33 months) in patients without EGFR. EGFR expression was significantly higher in female patients compared to male (p = 0.037).This study confirms the presence of EGFR in AML and indicates that EGFR expression confers poor prognosis in AML. However, the underlying cause of this adverse prognostic effect has not been identified. Further clinical studies are warranted to determine the exact mechanism through which EGFR activity might contribute to AML progression and identify the potential therapeutic target for the reversal of resistance to conventional chemotherapeutics.

HB-EGF-EGFR Signaling in Bone Marrow Endothelial Cells Mediates Angiogenesis Associated with Multiple Myeloma

Epidermal growth factor receptor (EGFR) and its ligand heparin-binding EGF-like growth factor (HB-EGF) sustain endothelial cell proliferation and angiogenesis in solid tumors, but little is known about the role of HB-EGF–EGFR signaling in bone marrow angiogenesis and multiple myeloma (MM) progression. We found that bone marrow endothelial cells from patients with MM express high levels of EGFR and HB-EGF, compared with cells from patients with monoclonal gammopathy of undetermined significance, and that overexpressed HB-EGF stimulates EGFR expression in an autocrine loop. We also found that levels of EGFR and HB-EGF parallel MM plasma cell number, and that HB-EGF is a potent inducer of angiogenesis in vitro and in vivo. Moreover, blockade of HB-EGF–EGFR signaling, by an anti-HB-EGF neutralizing antibody or the EGFR inhibitor erlotinib, limited the angiogenic potential of bone marrow endothelial cells and hampered tumor growth in an MM xenograft mouse model. These results identify HB-EGF–EGFR signaling as a potential target of anti-angiogenic therapy, and encourage the clinical investigation of EGFR inhibitors in combination with conventional cytotoxic drugs as a new therapeutic strategy for MM.

MMP-2 and MMP-9 mediate cigarette smoke extract-induced epithelial-mesenchymal transition in airway epithelial cells via EGFR/Akt/GSK3β/β-catenin pathway: Amelioration by fisetin

Matrix metalloproteinases (MMPs) have been implicated in EMT but their role in the regulation of cigarette smoke-induced EMT in airway epithelium is not clear. We have therefore investigated the potential role of MMP-2 and -9 in cigarette smoke extract (CSE) induced EMT using A549 lung epithelial cells and human small airway epithelial cells (SAEC). The cells were treated with different concentration of CSE, and MTT and trypan blue assays, acridine orange-ethidium bromide assay, gelatin zymography, Western blotting, immunofluorescence studies, Boyden-chamber assay, wound healing assay and air-liquid interface (ALI) culture were used to assess different cellular and molecular changes associated with EMT. The results depict that CSE increased the cytotoxicity along with a concurrent increase in the expression and activity of MMP-2 and -9. CSE further altered EMT markers like E-cadherin, N-cadherin, vimentin, and the molecular modulators of EMT such as β-catenin and pGSK-3β. Further, CSE also upregulated EGFR, AKT, and ERK1/2 in airway epithelial cells. SB-3CT, a known inhibitor of MMP-2 and -9, altered and reversed the expression of markers of EMT and kinases, validating the role of MMP-2 and -9 in CSE-induced EMT. Fisetin, a plant-derived bioflavonoid, also reversed the expression of EMT markers and molecular regulators in a similar fashion as SB-3CT. In summary, this study highlights the role of MMP-2 and -9 in CSE-induced EMT and curate its molecular cascade through EGFR/AKT/ERK/β-catenin axis, which could be restored by MMP-2 and -9 inhibitor and fisetin. Fisetin is hitherto unknown to modulate CSE-induced MMPs activity in airway epithelial cells, and our study suggests its potential role as a therapeutic approach in CSE-induced EMT in lung epithelial cells.

The tumor-suppressive function of miR-1296-5p by targeting EGFR and CDK6 in gastric cancer

We aimed to confirm the role of miR-1296-5p in gastric cancer and to identify its target genes. The expression of miR-1296-5p was measured in gastric cancer tissues and cell lines. The function of miR-1296-5p was examined by the overexpression and inhibition of its expression in typical gastric cell lines as well as SGC-7901 and MGC-803 cells. The targets of miR-1296-5p were identified by a luciferase activity assay. We found that miR-1296-5p was down-regulated in gastric cancer tissue and cell lines, and low expression levels of miR-1296-5p were associated with advanced clinical stage. Moreover, miR-1296-5p inhibited cell proliferation, migration, and invasion in SGC-7901 and MGC-803 cells. Then, we identified CDK6 and EGFR as novel targets of miR-1296-5p by a luciferase activity assay. Furthermore, the overexpression of miR-1296-5p suppressed the expression of CDK6 and EGFR. Our results indicated a tumor-suppressive role of miR-1296-5p through the translational repression of oncogenic CDK6 and EGFR in gastric cancer.

Antibodies and Derivatives Targeting DR4 and DR5 for Cancer Therapy

Developing therapeutics that induce apoptosis in cancer cells has become an increasingly attractive approach for the past 30 years. The discovery of tumor necrosis factor (TNF) superfamily members and more specifically TNF-related apoptosis-inducing ligand (TRAIL), the only cytokine of the family capable of eradicating selectively cancer cells, led to the development of numerous TRAIL derivatives targeting death receptor 4 (DR4) and death receptor 5 (DR5) for cancer therapy. With a few exceptions, preliminary attempts to use recombinant TRAIL, agonistic antibodies, or derivatives to target TRAIL agonist receptors in the clinic have been fairly disappointing. Nonetheless, a tremendous effort, worldwide, is being put into the development of novel strategic options to target TRAIL receptors. Antibodies and derivatives allow for the design of novel and efficient agonists. We summarize and discuss here the advantages and drawbacks of the soar of TRAIL therapeutics, from the first developments to the next generation of agonistic products, with a particular insight on new concepts.

MicroRNA 125a-5p Inhibits Cell Proliferation and Induces Apoptosis in Hepatitis B Virus-Related Hepatocellular Carcinoma by Downregulation of ErbB3

MicroRNAs, a class of endogenous noncoding RNAs, regulate gene expression at the posttranscriptional level and thus take part in multiple biological processes. An increasing number of miRNAs have been found to be dysregulated in hepatocellular carcinoma (HCC) and are involved in liver tumorigenesis. In this study, miR-125a-5p was found to be obviously downregulated much more in hepatitis B virus (HBV)-related HCC. To investigate the effects of miR-125a-5p, miR-125a-5p was overexpressed in HepG2.2.15 and HepG3X cells. The findings have indicated that overexpression of miR-125a-5p dramatically inhibited cell proliferation and induced cell apoptosis. Furthermore, overexpression of miR-125a-5p could significantly decrease the secretion of HBsAg and HBeAg. In concordance to this, the expression of ErbB3 was upregulated in human HBV-related HCC tissue, HepG2.2.15 cells, and HepG3X cells. miR-125a-5p directly targeted ErbB3 and reduced both mRNA and protein levels of ErbB3, which promoted cell proliferation and suppressed cell apoptosis in HCC cells. Our results provide new insights into the function of miR-125a-5p in HBV-related HCC. It is beneficial to gain insight into the mechanism of HBV infection and pathophysiology of HBV-related HCC.

Functional characterization of wild-type and 24 CYP2D6 allelic variants on gefitinib metabolism in vitro

Background

Cytochrome P450 2D6 (CYP2D6), a member of the CYP450 enzyme super family, is a polymorphic enzyme that metabolizes ~25% of therapeutic drugs. CYP2D6 exhibits significant genetic polymorphisms which might cause adverse effects and therapeutic failures of some drugs.

Objective

The purpose of this study was to evaluate the catalytic activities of 22 novel CYP2D6 alleles (CYP2D6*87, *88, *89, *90, *91, *92, *93, *94, *95, *96, *97, *98, R25Q, F164L, E215K, F219S, V327M, D336N, V342M, R344Q, R440C, R497C) on the metabolism of gefitinib in vitro.

Methods and results

CYP2D6 variants were incubated with 1–100 μM gefitinib for 60 min at 37°C and the reaction was terminated by cooling to −80°C immediately. Gefitinib and its metabolite O-desmethyl gefitinib were analyzed by an ultra-performance liquid chromatography-tandem mass spectrometry system. Compared to CYP2D6.1, most CYP2D6 variants exhibited significantly decreased relative clearance values (from 3.11% to 79.35%), whereas CYP2D6.92 and CYP2D6.96 displayed no detectable enzyme activity. Only CYP2D6.94 exhibited a markedly increased intrinsic clearance value, and eight variants (CYP2D6.88, CYP2D6.89, CYP2D6.91, CYP2D6.97, V342M, R344Q, F219S, and F164L) showed no significant difference. In addition, 23 CYP2D6 allelic isoforms exhibited substrate inhibition trend toward gefitinib.

Conclusion

As the first study of all the aforementioned alleles for gefitinib metabolism, these comprehensive data may help in the clinical assessment of the metabolism of gefitinib, and may also offer a reference for personalized treatment with gefitinib in clinical settings.

NMR-based metabolomics Reveals Alterations of Electro-acupuncture Stimulations on Chronic Atrophic Gastritis Rats

Chronic atrophic gastritis (CAG) is a common gastrointestinal disease which has been considered as precancerous lesions of gastric carcinoma. Previously, electro-acupuncture stimulation has been shown to be effective in ameliorating symptoms of CAG. However the underlying mechanism of this beneficial treatment is yet to be established. In the present study, an integrated histopathological examination along with molecular biological assay, as well as ¹H NMR analysis of multiple biological samples (urine, serum, stomach, cortex and medulla) were employed to systematically assess the pathology of CAG and therapeutic effect of electro-acupuncture stimulation at Sibai (ST 2), Liangmen (ST 21), and Zusanli (ST 36) acupoints located in the stomach meridian using a rat model of CAG. The current results showed that CAG caused comprehensive metabolic alterations including the TCA cycle, glycolysis, membrane metabolism and catabolism, gut microbiota-related metabolism. On the other hand, electro-acupuncture treatment was found able to normalize a number of CAG-induced metabolomics changes by alleviating membrane catabolism, restoring function of neurotransmitter in brain and partially reverse the CAG-induced perturbation in gut microbiota metabolism. These findings provided new insights into the biochemistry of CAG and mechanism of the therapeutic effect of electro-acupuncture stimulations.

Understanding EGFR Signaling in Breast Cancer and Breast Cancer Stem Cells: Overexpression and Therapeutic Implications

Epidermal growth factor receptors (EGFRs/HERs) and downstream signaling pathways have been implicated in the pathogenesis of several malignancies including breast cancer and its resistance to treatment with chemotherapeutic drugs. Consequently, several monoclonal antibodies as well as small molecule inhibitors targeting these pathways have emerged as therapeutic tools in the recent past. However, studies have shown that utilizing these molecules in combination with chemotherapy has yielded only limited success. This review describes the current understanding of EGFRs/HERs and associated signaling pathways in relation to development of breast cancer and responses to various cancer treatments in the hope of pointing to improved prevention, diagnosis and treatment. Also, we review the role of breast cancer stem cells (BCSCs) in disease and the potential to target these cells.

Focal Adhesion Kinase Inhibitors in Combination with Erlotinib Demonstrate Enhanced Anti-Tumor Activity in Non-Small Cell Lung Cancer

Blockade of epidermal growth factor receptor (EGFR) activity has been a primary therapeutic target for non-small cell lung cancers (NSCLC). As patients with wild-type EGFR have demonstrated only modest benefit from EGFR tyrosine kinase inhibitors (TKIs), there is a need for additional therapeutic approaches in patients with wild-type EGFR. As a key component of downstream integrin signalling and known receptor cross-talk with EGFR, we hypothesized that targeting focal adhesion kinase (FAK) activity, which has also been shown to correlate with aggressive stage in NSCLC, would lead to enhanced activity of EGFR TKIs. As such, EGFR TKI-resistant NSCLC cells (A549, H1299, H1975) were treated with the EGFR TKI erlotinib and FAK inhibitors (PF-573,228 or PF-562,271) both as single agents and in combination. We determined cell viability, apoptosis and 3-dimensional growth in vitro and assessed tumor growth in vivo. Treatment of EGFR TKI-resistant NSCLC cells with FAK inhibitor alone effectively inhibited cell viability in all cell lines tested; however, its use in combination with the EGFR TKI erlotinib was more effective at reducing cell viability than either treatment alone when tested in both 2- and 3-dimensional assays in vitro, with enhanced benefit seen in A549 cells. This increased efficacy may be due in part to the observed inhibition of Akt phosphorylation when the drugs were used in combination, where again A549 cells demonstrated the most inhibition following treatment with the drug combination. Combining erlotinib with FAK inhibitor was also potent in vivo as evidenced by reduced tumor growth in the A549 mouse xenograft model. We further ascertained that the enhanced sensitivity was irrespective of the LKB1 mutational status. In summary, we demonstrate the effectiveness of combining erlotinib and FAK inhibitors for use in known EGFR wild-type, EGFR TKI resistant cells, with the potential that a subset of cell types, which includes A549, could be particularly sensitive to this combination treatment. As such, further evaluation of this combination therapy is warranted and could prove to be an effective therapeutic approach for patients with inherent EGFR TKI-resistant NSCLC.

Hepatitis B virus X protein reduces the stability of Nrdp1 to up-regulate ErbB3 in hepatocellular carcinoma cells

Hepatitis B virus (HBV)-associated hepatocellular carcinoma (HCC) is the most widespread type of liver cancer. However, the underlying mechanism of HCC tumorigenesis is very intricate and HBV-encoded X protein (HBx) has been reported to play a key role in this process. It has been reported that HBx up-regulates the transcription of ErbB3. However, it remains unclear whether HBx can regulate ErbB3 expression at post-translational modification level. In this study, we showed that HBx interacts with ubiquitin ligase Nrdp1 (neuregulin receptor degradation protein 1) and decreases its stability, which results in the up-regulation of ErbB3 and promotion of HCC cells. Moreover, the expression of ErbB3 was almost undetectable in normal liver tissues but was relative abundant in HCC tissues, and the level of ErbB3 and Nrdp1 significantly showed a negative correlation in HCC tissues. Taken together, these findings suggest that HBx promotes the progression of HCC by decreasing the stability of Nrdp1, which results in up-regulation of ErbB3, suggesting that ErbB3 may be a target for HCC therapy.

Gefitinib-induced intestinal obstruction in advanced non-small cell lung carcinoma: A case report

Gefitinib is an epidermal growth factor receptor (EGFR) inhibitor, which is used to treat patients with advanced non-small cell lung cancer (NSCLC) harboring EGFR mutations. Dermatological reactions are the most common adverse events associated with gefitinib treatment; other adverse effects, including diarrhea, nausea, stomatitis and an asymptomatic elevation of liver enzymes have also been reported. The present study describes a patient with intestinal obstruction who was successfully undergoing treatment with gefitinib for primary and metastatic neoplasms. Gefitinib-induced intestinal obstruction has not been previously reported; therefore, careful monitoring of gastrointestinal symptoms should be conducted throughout the course of gefitinib-treated malignancies.

Molecular recognition of HER-1 in whole-blood samples

Multimode sensing was proposed for molecular screening and recognition of HER-1 in whole blood. The tools used for molecular recognition were platforms based on nanostructured materials such as the complex of Mn(III) with meso-tetra (4-carboxyphenyl) porphyrin, and maltodextrin (dextrose equivalence between 4 and 7), immobilized in diamond paste, graphite paste or C60 fullerene paste. The identification of HER-1 in whole-blood samples, at molecular level, is performed using stochastic mode and is followed by the quantification of it using stochastic and differential pulse voltammetry modes. HER-1 can be identified in the concentration range between 280 fg/ml and 4.86 ng/ml using stochastic mode, this making possible the early detection of cancers such as gastrointestinal, pancreatic and lung cancers. The recovery tests performed using whole-blood samples proved that the platforms can be used for identification and quantification of HER-1 with high sensitivity and reliability in such samples, these making them good molecular screening tools.

Hypermethylated Epidermal growth factor receptor (EGFR) promoter is associated with gastric cancer

Epidermal growth factor receptor (EGFR) is a member of the receptor tyrosine kinases ErbB family and it is found to be overexpressed in gastric cancer. However, the mechanism of the regulation of the EGFR expression is still unknown. We used the Sequenom EpiTYPER assay to detect the methylation status of the EGFR promoter in normal and tumour tissues of 30 patients with gastric cancer. We also carried out quantitative real time PCR (qPCR) to detect the expression level of EGFR in our 30 patients. Notably, increased methylation level at EGFR promoter was found in tumour tissues than the corresponding adjacent noncancerous. In both Region I DMR and Region II DMR detected in our study, tumor tissues were significantly hypermethylated (P=2.7743E-10 and 2.1703E-05, respectively). Region I_⊿CpG_2 was also found to be associated with the presence of distant metastasis (P=0.0323). Furthermore, the results showed a strongly significant association between the relative EGFR expression and the EGFR methylation changes in both Region I and Region II (P=0.0004 and 0.0001, respectively). Our findings help to indicate the hypermethylation at EGFR promoter in gastric cancer and it could be a potential epigenetic biomarker for gastric cancer status and progression.

Enhanced cytotoxic activity of cetuximab in EGFR-positive lung cancer by conjugating with gold nanoparticles

Cetuximab (C225) is a unique agent, targeting epidermal growth factor receptor (EGFR)-positive cancer. However, the therapeutic effect of C225 in EGFR high-expressing non-small cell lung cancer (NSCLC) remains poor. Here, we report that conjugation of C225 with gold nanoparticles (AuNPs) enhances the cytotoxicity of C225 in NSCLC both in vitro and in vivo. The NSCLC cell lines A549 (EGFR^high) and H1299 (EGFR^low) were employed to investigate different responses to C225, IgG-AuNPs and C225-AuNPs. The antitumor properties of C225-AuNPs were explored in vivo by establishing a tumor xenograft model in nude mice. Overall, the therapeutic effect of C225-AuNPs was more pronounced in EGFR^high A549 cells compared with EGFR^low H1299 cells. The cytotoxic effect of C225-AuNPs in A549 cells increased in a dose-dependent manner. C225-AuNPs significantly suppressed A549 cell proliferation and migration capacity and accelerated apoptosis compared with C225, and this effect was probably due to enhanced EGFR endocytosis and the subsequent suppression of downstream signaling pathway. Finally in the tumor xenograft of nude mice, treatment with C225-AuNPs also led to a significant reduction in tumor weight and volume with low toxicity. Our findings suggest that C225-AuNPs conjugate has promising potential for targeted therapy of EGFR positive NSCLC patients.

[Advances of driver gene and targeted therapy of non-small cell lung cancer]

Lung cancer is the leading cause of cancer-related mortality in the worldwide. The discovery of drive gene makes tumor treatment is no longer "one-size-fits-all". Targeted therapy to change the present situation of cancer drugs become "bullet" with eyes, the effect is visible and bring a revolution in the treatment of lung cancer. The diver gene and targeted therapy have became the new cedule of non-small cell lung cancer (NSCLC). Society of Clinical Oncology (ASCO) has showed 11 kinds of diver genes. Here, we review the functional and structural characteristics and the targeted therapy in the 11 kinds of driver gene mutations.

Piperlongumine, an alkaloid causes inhibition of PI3 K/Akt/mTOR signaling axis to induce caspase-dependent apoptosis in human triple-negative breast cancer cells

The phosphatidylinositol 3-kinase (PI3 K)/Akt/mammalian target of rapamycin (mTOR) signaling axis plays a central role in cell proliferation, growth and survival under physiological conditions. However, aberrant PI3 K/Akt/mTOR signaling has been implicated in many human cancers, including human triple negative breast cancer. Therefore, dual inhibitors of PI3 K/Akt and mTOR signaling could be valuable agents for treating breast cancer. The objective of this study was to investigate the effect of piperlongumine (PPLGM), a natural alkaloid on PI3 K/Akt/mTOR signaling, Akt mediated regulation of NF-kB and apoptosis evasion in human breast cancer cells. Using molecular docking studies, we found that PPLGM physically interacts with the conserved domain of PI3 K and mTOR kinases and the results were comparable with standard dual inhibitor PF04691502. Our results demonstrated that treatment of different human triple-negative breast cancer cells with PPLGM resulted in concentration- and time-dependent growth inhibition. The inhibition of cancer cell growth was associated with G1-phase cell cycle arrest and down-regulation of the NF-kB pathway leads to activation of the mitochondrial apoptotic pathway. It was also found that PPLGM significantly decreased the expression of p-Akt, p70S6K1, 4E-BP1, cyclin D1, Bcl-2, p53 and increased expression of Bax, cytochrome c in human triple-negative breast cancer cells. Although insulin treatment increased the phosphorylation of Akt (Ser473), p70S6K1, 4E-BP1, PPLGM abolished the insulin mediated phosphorylation, it clearly indicates that PPLGM acts through PI3 k/Akt/mTOR axis. Our results suggest that PPLGM may be an effective therapeutic agent for the treatment of human triple negative breast cancer.

Concomitant EGFR inhibitors combined with radiation for treatment of non-small cell lung carcinoma

Epidermal growth factor receptor (EGFR) is considered to be one of the key driver genes in non-small cell lung cancer (NSCLC). Several clinical trials have shown great promise of EGFR tyrosine kinase inhibitors (TKIs) in the first-line treatment of NSCLC. Many advances have been made in the understanding of EGFR signal transduction network and the interaction between EGFR and tumor microenvironment in mediating cancer survival and development. The concomitant targeted therapy and radiation is a new strategy in the treatment of NSCLC. A number of preclinical studies have demonstrated synergistic anti-tumor activity in the combination of EGFR inhibitors and radiotherapy in vitro and in vivo. In the present review, we discuss the rationale of the combination of EGFR inhibitors and radiotherapy in the treatment of NSCLC.

The role of epidermal growth factor receptor in prognosis and treatment of gastric cancer

Despite tremendous efforts to reduce deaths due to gastric cancer, it represents the second leading cause of cancer-related deaths worldwide. EGF receptor (EGFR) plays important roles in gastric carcinogenesis by regulation of cell cycle, angiogenesis and apoptosis. This review evaluates the functions, mechanisms and clinical uses of EGFR in gastric cancer. Although EGFR targeted single therapy shows limited effect, the combination of EGFR targeted agents with traditional chemotherapy regimens may bring about important progress in cancer therapy. More clinical trials should be performed to clarify both the prognostic and therapeutic value of EGFR in gastric cancer.

Intrinsic caspase-8 activation mediates sensitization of erlotinib-resistant tumor cells to erlotinib/cell-cycle inhibitors combination treatment

Inhibitors of the tyrosine kinase activity of epidermal growth factor receptor, as erlotinib, have an established role in treating several cancer types. However, resistance to erlotinib, particularly in breast cancer cell lines, and erlotinib treatment-associated disorders have also been described. Also, methods and combination therapies that could reverse resistance and ameliorate non-desirable effects represent a clinical challenge. Here, we show that the ATP non-competitive CDK2/cyclin A inhibitor NBI1 sensitizes erlotinib-resistant tumor cells to the combination treatment (co-treatment) for apoptosis-mediated cell death. Furthermore, in erlotinib-sensitive cells, the effective dose of erlotinib was lower in the presence of NBI1. The analysis in the breast cancer MDA-MB-468 erlotinib-resistant and in lung cancer A549 cell lines of the molecular mechanism underlying the apoptosis induced by co-treatment highlighted that the accumulation of DNA defects and depletion of cIAP and XIAP activates the ripoptosome that ultimately activates caspases-8 and -10 and apoptosis. This finding could have significant implications for future treatment strategies in clinical settings.

Targeting Stat3 and Smad7 to restore TGF-β cytostatic regulation of tumor cells in vitro and in vivo

Transforming Growth Factor-β (TGF-β) and Epidermal Growth Factor (EGF) signaling pathways are both independently implicated as key regulators in tumor formation and progression. Here, we report that the tumor-associated overexpression of epidermal growth factor receptor (EGFR) desensitizes TGF-β signaling and its cytostatic regulation through specific and persistent Stat3 activation and Smad7 induction in vivo. In human tumor cell lines, reduction of TGF-β-mediated Smad2 phosphorylation, nuclear translocation and Smad3 target gene activation were observed when EGFR was overexpressed, but not in cells that expressed EGFR at normal levels. We identified Stat3, which is activated specifically and persistently by overexpressed EGFR, as a key signaling molecule responsible for the reduced TGF-β sensitivity. Stable knockdown of Stat3 using small hairpin RNA(shRNA) in Head and Neck (HN5) and Epidermoid (A431) tumor cell lines resulted in reduced growth compared with control shRNA-transfected cells when grown as subcutaneous tumor xenografts. Furthermore, xenografts with Stat3 knockdown displayed increased Smad3 transcriptional activity, increased Smad2 phosphorylation and decreased Smad7 expression compared with control xenografts in vivo. Consistently, Smad7 mRNA and protein expression was also significantly reduced when EGFR activity was blocked by a specific tyrosine kinase inhibitor, AG1478, or in Stat3 knockdown tumors. Similarly, Smad7 knockdown also resulted in enhanced Smad3 transcriptional activity in vivo. Importantly, there was no uptake of subcutaneous HN5 xenografts with Smad7 knockdown. Taken together, we demonstrate here that targeting Stat3 or Smad7 for knockdown results in resensitization of TGF-β's cytostatic regulation in vivo. Overall, these results establish EGFR/Stat3/Smad7/TGF-β signaling axis driving tumor growth, which can be targeted therapeutically.

RUNX3 downregulation in human lung adenocarcinoma is independent of p53, EGFR or KRAS status

RUNX3 aberrations play a pivotal role in the oncogenesis of breast, gastric, colon, skin and lung tissues. The aim of this study was to characterize further the expression of RUNX3 in lung cancers. To achieve this, a lung cancer tissue microarray (TMA), frozen lung cancer tissues and lung cell lines were examined for RUNX3 expression by immunohistochemistry, while the TMA was also examined for EGFR and p53 expression. RUNX3 promoter methylation status, and EGFR and KRAS mutation status were also investigated. Inactivation of RUNX3 was observed in 70% of the adenocarcinoma samples, and this was associated with promoter hypermethylation but not biased to EGFR/KRAS mutations. Our results suggest a central role of RUNX3 downregulation in pulmonary adenocarcinoma, which may not be dependent of other established cancer-causing pathways and may have important diagnostic and screening implications.

Intracytoplasmic epidermal growth factor receptor shows poor response to the cetuximab antitumor effect in irradiated non-small cell lung cancer cell lines

PURPOSE

The purpose of this study was to evaluate the antitumor effect of a blocking antibody for EGFR in the cytoplasm of a lung cancer cell line.

METHODS & MATERIALS

The A549 and H1299 cell lines were employed to demonstrate differential responses to cetuximab in combination with radiotherapy. Localization of EGFR was detected using confocal microscopy, and radiosensitivity was measured.

RESULTS

Treatment with cetuximab inhibited colony formation in a dose-dependent manner in A549, but not H1299 cells. Confocal microscopy revealed EGFR localized in the cytosolic fraction, particularly around the golgi apparatus in H1299, in contrast to cell membrane localization in A549 cell line. After irradiation, nuclear EGFR was detected in the A549 cell line. However, EGFR did not translocate to the nucleus in H1299 cells. While EGFR expression was decreased in both A549 and H1299 cell lines upon treatment with a combination of cetuximab and radiation, radiosensitivity was increased solely in A549 cells.

CONCLUSIONS

Our findings suggest that localization of EGFR is related to the sensitivity/resistance of cells to a combination of cetuximab and radiotherapy.

Epidermal growth factor gene polymorphism and risk of hepatocellular carcinoma: a meta-analysis

BACKGROUND

Hepatocarcinogenesis is a complex process that may be influenced by many factors, including polymorphism in the epidermal growth factor (EGF) gene. Previous work suggests an association between the EGF 61*A/G polymorphism (rs4444903) and susceptibility to hepatocellular carcinoma (HCC), but the results have been inconsistent. Therefore, we performed a meta-analysis of several studies covering a large population to address this controversy.

METHODS

PubMed, EMBASE, Google Scholar and the Chinese National Knowledge Infrastructure databases were systematically searched to identify relevant studies. Data were abstracted independently by two reviewers. A meta-analysis was performed to examine the association between EGF 61*A/G polymorphism and susceptibility to HCC. Odds ratios (ORs) and 95% confidence intervals (95% CIs) were calculated.

RESULTS

Eight studies were chosen in this meta-analysis, involving 1,304 HCC cases (1135 Chinese, 44 Caucasian and 125 mixed) and 2,613 controls (1638 Chinese, 77 Caucasian and 898 mixed). The EGF 61*G allele was significantly associated with increased risk of HCC based on allelic contrast (OR = 1.29, 95% CI = 1.16-1.44, p<0.001), homozygote comparison (OR = 1.79, 95% CI = 1.39-2.29, p<0.001) and a recessive genetic model (OR = 1.34, 95% CI = 1.16-1.54, p<0.001), while patients carrying the EGF 61*A/A genotype had significantly lower risk of HCC than those with the G/A or G/G genotype (A/A vs. G/A+G/G, OR = 0.66, 95% CI = 0.53-0.83, p<0.001).

CONCLUSION

The 61*G polymorphism in EGF is a risk factor for hepatocarcinogenesis while the EGF 61*A allele is a protective factor. Further large and well-designed studies are needed to confirm this conclusion.

Epidermal growth factor receptor expression in urinary bladder cancer

Objective:

To evaluate the expression pattern of epidermal growth factor receptor (EGFR) in urinary bladder cancer and its association with human epidermal growth factor receptor 2 (HER2), epidermal growth factor (EGF), interleukin-6 (IL-6), and high risk human papilloma virus (HPV) types 16 and 18.

Materials and Methods:

Thirty cases of urothelial carcinoma were analyzed. EGFR, HER2, EGF, and IL-6 expressions in the tissue were evaluated by immunohistochemical staining. For HPV, DNA from tissue samples was extracted and detection of HPV was done by PCR technique. Furthermore, evaluation of different intracellular molecules associated with EGFR signaling pathways was performed by the western blot method using lysates from various cells and tissues.

Results:

In this study, the frequencies of immunopositivity for EGFR, HER2, EGF, and IL-6 were 23%, 60%, 47%, and 80%, respectively. No cases were positive for HPV-18, whereas HPV-16 was detected in 10% cases. Overall, expression of EGFR did not show any statistically significant association with the studied parameters. However, among male patients, a significant association was found only between EGFR and HER2.

Conclusions:

Overexpression of EGFR and/or HER2, two important members of the same family of growth factor receptors, was observed in a considerable proportion of cases. Precise knowledge in this subject would be helpful to formulate a rational treatment strategy in patients with urinary bladder cancer.

Plasma transforming growth factor alpha and amphiregulin protein levels in NCIC Clinical Trials Group BR.21

PURPOSE

To evaluate the prognostic and predictive significance of plasma levels of the epidermal growth factor receptor (EGFR) ligands, transforming growth factor α (TGF-α) and amphiregulin, in patients with non-small-cell lung cancer (NSCLC) enrolled in NCIC Clinical Trials Group BR.21 comparing erlotinib with placebo.

PATIENTS AND METHODS

TGF-α and amphiregulin were assessed retrospectively by enzyme-linked immunosorbent assay from available prospectively collected baseline plasma samples in 565 of 731 BR.21 patients. Cutoff points were determined for both amphiregulin (low, <10 pg/mL; high, ≥10 pg/mL) and TGF-α (low, ≤12 pg/mL; high, >12 pg/mL) using a graphical method. Cox regression models were used to correlate biomarker data and baseline characteristics with outcomes including overall (OS) and progression-free survival (PFS).

RESULTS

High TGF-α and amphiregulin were associated with poorer performance status (P=.06 and P<.0001, respectively) and no prior platinum therapy (P=.06 and P=.02, respectively). High amphiregulin was also associated with anemia (P=.001), increased lactate dehydrogenase (P=.03), ever-smokers (P=.04), and non-Asian ethnicity (P=.001). Patients on the placebo arm with high amphiregulin had poorer OS than patients with low amphiregulin (hazard ratio [HR]=1.88; 95% CI, 1.34 to 2.64; P=.0002), which remained significant in multivariate analysis. Amphiregulin levels did not predict for benefit from erlotinib (interaction P=.87). Conversely, TGF-α levels did not have prognostic significance, but high TGF-α predicted lack of benefit from erlotinib compared with low TGF-α (TGF-α low, OS HR=0.66; 95% CI, 0.54 to 0.81; P<.0001; high, OS HR=1.32; 95% CI, 0.73 to 2.39; P=.36; interaction P=.04).

CONCLUSION

High baseline amphiregulin is a poor prognostic factor, whereas high baseline TGF-α predicts for lack of benefit from erlotinib in advanced NSCLC.

Effects of Src inhibitors on cell growth and epidermal growth factor receptor and MET signaling in gefitinib-resistant non-small cell lung cancer cells with acquired MET amplification

The efficacy of epidermal growth factor receptor (EGFR)-tyrosine kinase inhibitors such as gefitinib and erlotinib in non-small cell lung cancer (NSCLC) is often limited by the emergence of drug resistance conferred either by a secondary T790M mutation of EGFR or by acquired amplification of the MET gene. We now show that the extent of activation of the tyrosine kinase Src is markedly increased in gefitinib-resistant NSCLC (HCC827 GR) cells with MET amplification compared with that in the gefitinib-sensitive parental (HCC827) cells. In contrast, the extent of Src activation did not differ between gefitinib-resistant NSCLC (PC9/ZD) cells harboring the T790M mutation of EGFR and the corresponding gefitinib-sensitive parental (PC9) cells. This activation of Src in HCC827 GR cells was largely abolished by the MET-TKI PHA-665752 but was only partially inhibited by gefitinib, suggesting that Src activation is more dependent on MET signaling than on EGFR signaling in gefitinib-resistant NSCLC cells with MET amplification. Src inhibitors blocked Akt and Erk signaling pathways, resulting in both suppression of cell growth and induction of apoptosis, in HCC827 GR cells as effectively as did the combination of gefitinib and PHA-665752. Furthermore, Src inhibitor dasatinib inhibited tumor growth in HCC827 GR xenografts to a significantly greater extent than did treatment with gefitinib alone. These results provide a rationale for clinical targeting of Src in gefitinib-resistant NSCLC with MET amplification.

PET-based biodistribution and radiation dosimetry of epidermal growth factor receptor-selective tracer 11C-PD153035 in humans

The present study estimated the biodistribution and radiation-absorbed dose of epidermal growth factor receptor (EGFR) radioligand 11C-PD153035 in whole-body PET examinations of healthy volunteers.

METHODS

Two-dimensional whole-body PET was performed on 9 subjects after injection of 11C-PD153035 at 329.3+/-77.8 MBq (mean+/-SD). A total of 12 frames were acquired for approximately 90 min in 7 segments of the body. Regions of interest were drawn on PET images of source organs. Residence time was calculated as the area under the time-activity curve. Radiation dosimetry was calculated from organ residence time by use of MIRDOSE3 software.

RESULTS

The renal and hepatobiliary systems played important roles in 11C-PD153035 excretion from the body, accounting for the excretion of approximately 23% and 19% of the injected radioactivity, respectively. Blood-pool activity was only moderate and declined over time. Tracer accumulation in the lungs, bone marrow, and muscles was slight, resulting in low background activity in the chest. The organs with the highest radiation-absorbed doses were the urinary bladder and the gallbladder; the effective doses were 6.08E-02+/-1.85E-02 and 2.40E-02+/-8.01E-03 mGy/MBq, respectively. The effective dose equivalent was 7.43E-03+/-1.10E-03 mSv/MBq, and the dose-limiting organ was the urinary bladder.

CONCLUSION

On the basis of the estimated absorbed dose, 11C-PD153035 displayed a favorable radiation dose profile in humans and therefore could be used in multiple PET examinations of the same subject per year. 11C-PD153035 is a promising ligand for the investigation of EGFR in humans, especially in chest tumors such as non-small cell lung cancer.

Combined lapatinib and cetuximab enhance cytotoxicity against gefitinib-resistant lung cancer cells

Although non-small cell lung cancer (NSCLC) cells with somatic mutations in their epidermal growth factor receptors (EGFR) initially show a dramatic response to tyrosine kinase inhibitor (TKI), these cells eventually develop resistance to TKI. This resistance may be caused by a secondary T790M mutation in the EGFR tyrosine kinase, which leads to the substitution of methionine for threonine in 790. In this study, we show that a combination of lapatinib and cetuximab overcomes gefitinib resistance in NSCLC with the T790M mutation. We observed that T790M lung cancer cells were resistant to gefitinib, and Stat3 was persistently activated in the resistant cells. A reversible EGFR and HER2 TKI, lapatinib, decreased Stat3 activation by blocking heterodimerization of EGFR and HER2, which led to a modest increase in the inhibitory effect on gefitinib-resistant T790M cells. In addition to lapatinib, the anti-EGFR antibody, cetuximab, induced down-regulation of EGFR and apoptotic cell death in T790M cells. Finally, combined lapatinib and cetuximab treatment resulted in significantly enhanced cytotoxicity against gefitinib-resistant T790M cells in vitro and in vivo. Taken together, these data suggest that treatment with a combination of lapatinib and cetuximab, which induces dimeric dissociation and EGFR down-regulation, appears to be an effective strategy for treatment of patients with EGFR TKI-resistant NSCLC.

Osteoadherin is upregulated by mature osteoblasts and enhances their in vitro differentiation and mineralization

During the process of differentiation, osteoblasts commit through strictly controlled checkpoints under the influence of several growth factors, cytokines, and extracellular matrix (ECM) proteins. The mineralized tissue-specific ECM component osteoadherin (OSAD) belongs to the small leucine-rich repeat protein family of proteoglycans. Proteoglycans modulate cellular behavior either through the attached glycosaminoglycan chains or by direct protein-protein interactions via the core protein sequences. Leucine-rich repeats have been shown to directly interact with cell-surface receptors such as epidermal growth factor receptor, blocking its ability to bind its ligand. In the present study, we investigated the influence of OSAD on the behavior and maturation of MC3T3E1 osteoblasts. OSAD overexpression and repression clones were created by stably transfecting with plasmids coding for either mouse OSAD cDNA or small-hairpin RNA, targeted against mouse OSAD. Overexpression of OSAD resulted in an increase of osteoblast differentiation features, such as increased alkaline phosphatase (ALP) activity and increased in vitro mineralization, as well as reduced proliferation and migration. Bone sialoprotein (BSP) levels were unchanged, while upregulation of osteocalcin (OC) and osteoglycin (OGN) was observed. Conversely, repression of OSAD expression resulted in increased cell proliferation and migration. BSP and OC were unaffected, while OGN was downregulated. ALP activity was reduced, though no change in in vitro mineralization was observed. We conclude that OSAD overexpression enhanced the differentiation and maturation of osteoblasts in vitro.

EGFR, p16, HPV Titer, Bcl-xL and p53, sex, and smoking as indicators of response to therapy and survival in oropharyngeal cancer

PURPOSE

To prospectively identify markers of response to therapy and outcome in an organ-sparing trial for advanced oropharyngeal cancer.

PATIENTS AND METHODS

Pretreatment biopsies were examined for expression of epidermal growth factor receptor (EGFR), p16, Bcl-xL, and p53 as well as for p53 mutation. These markers were assessed for association with high-risk human papillomavirus (HPV), response to therapy, and survival. Patient variables included smoking history, sex, age, primary site, tumor stage, and nodal status.

RESULTS

EGFR expression was inversely associated with response to induction chemotherapy (IC) (P = .01), chemotherapy/radiotherapy (CRT; P = .055), overall survival (OS; P = .001), and disease-specific survival (DSS; P = .002) and was directly associated with current smoking (P = .04), female sex (P = .053), and lower HPV titer (P = .03). HPV titer was significantly associated with p16 expression (P < .0001); p16 was significantly associated with response to IC (P = .008), CRT (P = .009), OS (P = .001), and DSS (P = .003). As combined markers, lower HPV titer and high EGFR expression were associated with worse OS (rho(EGFR) = 0.008; rho(HPV) = 0.03) and DSS (rho(EGFR) = 0.01; rho(HPV) = 0.016). In 36 of 42 biopsies, p53 was wild-type, and only one HPV-positive tumor had mutant p53. The combination of low p53 and high Bcl-xL expression was associated with poor OS (P = .005) and DSS (P = .002).

CONCLUSION

Low EGFR and high p16 (or higher HPV titer) expression are markers of good response to organ-sparing therapy and outcome, whereas high EGFR expression, combined low p53/high Bcl-xL expression, female sex, and smoking are associated with a poor outcome. Smoking cessation and strategies to target EGFR and Bcl-xL are important adjuncts to the treatment of oropharyngeal cancer.

Enhancement of the antitumor activity of ionising radiation by nimotuzumab, a humanised monoclonal antibody to the epidermal growth factor receptor, in non-small cell lung cancer cell lines of differing epidermal growth factor receptor status

The expression and activity of the epidermal growth factor receptor (EGFR) are determinants of radiosensitivity in several tumour types, including non-small cell lung cancer (NSCLC). However, little is known of whether genetic alterations of EGFR in NSCLC cells affect the therapeutic response to monoclonal antibodies (mAbs) to EGFR in combination with radiation. We examined the effects of nimotuzumab, a humanised mAb to EGFR, in combination with ionising radiation on human NSCLC cell lines of differing EGFR status. Flow cytometry revealed that H292 and Ma-1 cells expressed high and moderate levels of EGFR on the cell surface, respectively, whereas H460, H1299, and H1975 cells showed a low level of surface EGFR expression. Immunoblot analysis revealed that EGFR phosphorylation was inhibited by nimotuzumab in H292 and Ma-1 cells but not in H460, H1299, or H1975 cells. Nimotuzumab augmented the cytotoxic effect of radiation in H292 and Ma-1 cells in a clonogenic assay in vitro, with a dose enhancement factor of 1.5 and 1.3, respectively. It also enhanced the antitumor effect of radiation on H292 and Ma-1 cell xenografts in nude mice, with an enhancement factor of 1.3 and 4.0, respectively. Nimotuzumab did not affect the radioresponse of H460 cells in vitro or in vivo. Nimotuzumab enhanced the antitumor efficacy of radiation in certain human NSCLC cell lines in vitro and in vivo. This effect may be related to the level of EGFR expression on the cell surface rather than to EGFR mutation.

EGFR expression as an ancillary tool for diagnosing lung cancer in cytology specimens

Lung cancer evolves in a multistep process, and its early detection portends a better prognosis. Bronchial washings/brushings and fine-needle aspirations are often used as early screening and cytological diagnosis of lung cancer. In some cases, it is difficult to differentiate morphologically malignant from reactive cells. Epidermal growth factor receptor (EGFR) is a transmembrane receptor overexpressed in high percentage lung cancers, and contributes to tumor growth. Assessing EGFR expression levels by fluorescence in situ hybridization (FISH) and immunohistochemistry (IHC) may provide critical information of tumor marker abnormalities, assist in the cytological diagnosis, and stratify patients for EGFR inhibitor therapy. Fifty patients with bronchial washings/brushings or fine-needle aspiration specimens, and corresponding histologically confirmed lung biopsies, were studied for EGFR expression with FISH and IHC. Copy numbers of the EGFR gene locus were analyzed with those of chromosome 7 by FISH. EGFR and FISH results were compared to our FISH data with combined EGFR, c-myc, 5p15.2, and chromosome 6 probes in selected cases. Cell blocks, if available, and tissue biopsy sections were used for EGFR IHC. The intensity of IHC was scored, and quantified. Only balanced aneuploidy of EGFR was identified by FISH. Gene amplification was not detected. The chromosomal abnormalities of EGFR were often accompanied by other chromosomal aneuploidies demonstrated in c-myc (8q24), 5p15.2 or 6p, indicating a general genomic instability. About half of the specimens with confirmed malignancy showed EGFR balanced aneuploidy by FISH, and gene copy number was not coupled with protein expression in many cases. The benign or reactive cytology specimens confirmed by biopsies had high specificity by FISH (96%) and IHC (88%). FISH and IHC analysis of EGFR, possibly along with other tumor markers, may be a useful ancillary tool to classify difficult cytology cases and inform clinicians arranging targeted chemotherapy.

Tumor growth inhibition with cetuximab and chemotherapy in non-small cell lung cancer xenografts expressing wild-type and mutated epidermal growth factor receptor

PURPOSE

Targeting the epidermal growth factor receptor (EGFR) is a validated approach to treat cancer. In non-small cell lung cancer (NSCLC), EGFR contains somatic mutations in 10% of patients, which correlates with increased response rates to small molecule inhibitors of EGFR. We analyzed the effects of the monoclonal IgG1 antibody Erbitux (cetuximab) in NSCLC xenografts with wild-type (wt) or mutated EGFR.

EXPERIMENTAL DESIGN

NSCLC cell lines were grown s.c. in nude mice. Dose-dependent efficacy was established for cetuximab. To determine whether combination therapy produces tumor regressions, cetuximab was dosed at half-maximal efficacy with chemotherapy used at maximum tolerated dose.

RESULTS

Cetuximab showed antitumor activity in wt (A549, NCI-H358, NCI-H292) and mutated [HCC-827 (delE746-A750), NCI-H1975 (L858R, T790M)] EGFR-expressing xenografts. In the H292 model, cetuximab and docetaxel combination therapy was more potent to inhibit tumor growth than cetuximab or docetaxel alone. Cisplatin augmented efficacy of cetuximab to produce 6 of 10 regressions, whereas 1 of 10 regressions was found with cetuximab and no regression was found with cisplatin. Using H1975 xenografts, gemcitabine increased efficacy of cetuximab resulting in 12 of 12 regressions. Docetaxel with cetuximab was more efficacious with seven of nine regressions compared with single treatments. Cetuximab inhibited autophosphorylation of EGFR in both H292 and H1975 tumor lysates. Exploring the underlying mechanism for combination effects in the H1975 xenograft model, docetaxel in combination with cetuximab added to the antiproliferative effects of cetuximab but was the main component in this drug combination to induce apoptosis.

CONCLUSIONS

Cetuximab showed antitumor activity in NSCLC models expressing wt and mutated EGFR. Combination treatments increased the efficacy of cetuximab, which may be important for the management of patients with chemorefractory NSCLC.

Les thérapeutiques ciblées en association avec la radiothérapie dans le cancer bronchique

Targeted therapies are now more often used in lung cancer. Inhibitors of EGFR and of angiogenesis have demonstrated a certain activity in this disease. Some experimental in vitro or in vivo studies are in favour of combined targeted therapies and radiation. For example, additive or supra-additive effects have been shown when inhibitors of the EGFR tyrosine kinase were given with radiation. In advanced lung cancer, the combination of bevacizumab with chemotherapy was demonstrated to produce better survival outcomes. But a high rate of fatal hemoptysis was reported with this drug, particularly for central and squamous tumors. This could be a limitation for its use in combination with radiation. Drugs with multiple targets are becoming available; their association with radiation seems to be promising.