Targeting the epidermal growth factor receptor

Strategies to address key challenges of metallacycle/metallacage-based supramolecular coordination complexes in biomedical applications

Owing to their capacity for dynamically linking two or more functional molecules, supramolecular coordination complexes (SCCs), exemplified by two-dimensional (2D) metallacycles and three-dimensional (3D) metallacages, have gained increasing significance in biomedical applications. However, their inherent hydrophobicity and self-assembly driven by heavy metal ions present common challenges in their applications. These challenges can be overcome by enhancing the aqueous solubility and in vivo circulation stability of SCCs, alongside minimizing their side effects during treatment. Addressing these challenges is crucial for advancing the fundamental research of SCCs and their subsequent clinical translation. In this review, drawing on extensive contemporary research, we offer a thorough and systematic analysis of the strategies employed by SCCs to surmount these prevalent yet pivotal obstacles. Additionally, we explore further potential challenges and prospects for the broader application of SCCs in the biomedical field.

6-Shogaol Overcomes Gefitinib Resistance via ER Stress in Ovarian Cancer Cells

In women, ovary cancer is already the fifth leading cause of mortality worldwide. The use of cancer therapies, such as surgery, radiotherapy, and chemotherapy, may be a powerful anti-cancer therapeutic strategy; however, these therapies still have many problems, including resistance, toxicity, and side effects. Therefore, natural herbal medicine has the potential to be used for cancer therapy because of its low toxicity, fewer side effects, and high success. This study aimed to investigate the anti-cancer effect of 6-shogaol in ovarian cancer cells. 6-shogaol induces ER stress and cell death via the reduction in cell viability, the increase in LDH cytotoxicity, caspase-3 activity, and Ca²⁺ release, and the upregulation of GRP78, p-PERK, p-eIF2α, ATF-4, CHOP, and DR5. Moreover, 6-shogaol treatment medicates endoplasmic reticulum (ER) stress and cell death by upregulating Nox4 and releasing ROS. The knockdown of Nox4 in ovarian cancer cells inhibits ER stress and cell death by blocking the reduction in cell viability and the enhancement of LDH cytotoxicity, caspase-3 activity, Ca²⁺, and ROS release. In gefitinib-resistant ovarian cancer cells, A2780R and OVCAR-3R, 6-shogaol/gefitinib overcomes gefitinib resistance by inhibiting EMT phenomena such as the reduction in E-cadherin, and the increase in N-cadherin, vimentin, Slug, and Snail. Therefore, our results suggest that 6-shogaol exerts a potential anti-cancer effect in ovarian cancer and combination treatment with 6-shogaol and gefitinib may provide a novel anti-tumor therapeutic strategy in gefitinib-resistant ovarian cancer.

A randomized, open-label, two-cycle, two-crossover phase I clinical trial comparing the bioequivalence and safety of afatinib and Giotrif® in healthy Chinese subjects

OBJECTIVE

Afatinib is an oral, irreversible ErbB family blocker. It binds covalently to the kinase domains of epidermal growth factor (EGFR), HER2 and HER4, resulting in irreversible inhibition of tyrosine kinase autophosphorylation. Our trial compared the bioequivalence and safety between afatinib produced by Chia Tai Tianqing Pharmaceutical Group Co., Ltd. and Giotrif^® produced by Boehringer Ingelheim.

METHODS

Healthy Chinese subjects (N = 36) were randomly divided into two groups at a ratio of 1:1. There was a single dose per period of afatinib and Giotrif^®. The washout was set as 14 days. Plasma drug concentrations of afatinib and Giotrif^® were analyzed by liquid chromatography-tandem mass spectrometry (LC-MS/MS). Statistical analysis of major pharmacokinetic (PK) parameters was conducted to assess drug bioequivalence. In addition, we evaluated the safety of the drugs throughout the trial.

RESULTS

The geometric mean ratios (GMRs) of C_max, AUC_0-t, and AUC_0-∞ for afatinib and Giotrif^® were 102.80%, 101.83%, and 101.58%, respectively. The 90% confidence intervals (CIs) were all within 80%-125%, meeting the bioequivalence standards. In addition, both drugs showed a good safety profile during the trial.

CONCLUSION

This study showed that afatinib was bioequivalent to Giotrif^® in healthy Chinese subjects with well safety.

CHINESE CLINICAL TRIAL REGISTRY

This trial is registered at the Chinese Clinical Trial website ( http://www.chinadrugtrials.org.cn/index.html # CTR20171160).

Bioluminescent RAPPID Sensors for the Single-Step Detection of Soluble Axl and Multiplex Analysis of Cell Surface Cancer Biomarkers

Early diagnosis of cancer is essential for the efficacy of treatment. Our group recently developed RAPPID, a bioluminescent immunoassay platform capable of measuring a wide panel of biomarkers directly in solution. Here, we developed and systematically screened different RAPPID sensors for sensitive detection of the soluble fraction of Axl (sAxl), a cell surface receptor that is overexpressed in several types of cancer. The best-performing RAPPID sensor, with a limit of detection of 8 pM and a >9-fold maximal change in emission ratio, was applied to measure Axl in three different contexts: clinically relevant sAxl levels (∼0.5 and ∼1 nM) in diluted blood plasma, proteolytically cleaved Axl in the cell culture medium of A431 and HeLa cancer cells, and Axl on the membrane of A431 cells. We further extended the sensor toolbox by developing dual-color RAPPID for simultaneous detection of Axl and EGFR on A431 and HeLa cells, as well as an AND-gate RAPPID that measures the concurrent presence of these two cell surface receptors on the same cell. These new RAPPID sensors provide attractive alternatives for more laborious protein detection and quantification methods such as FACS and immunostainings, due to their simple practical implantation and low intrinsic background signal.

New benzothienopyrimidine derivatives as dual EGFR/ARO inhibitors: Design, synthesis, and their cytotoxic effect on MCF-7 breast cancer cell line

New cytotoxic agents based on benzothienopyrimidine scaffold were designed, synthesized, and evaluated against the MCF-7 breast cancer line in comparison to erlotinib and letrozole as reference drugs. Eight compounds demonstrated up to 20-fold higher anticancer activity than erlotinib, and five of these compounds were up to 11-fold more potent than letrozole in MTT assay. The most promising compounds were evaluated for their inhibitory activity against EGFR and ARO enzymes. Compound 12, which demonstrated potent dual EGFR and ARO inhibitory activity with IC₅₀ of 0.045 and 0.146 µM, respectively, was further evaluated for caspase-9 activation, cell cycle analysis, and apoptosis. The results revealed that the tested compound 12 remarkably induced caspase-9 activation (IC₅₀  = 16.29 ng/ml) caused cell cycle arrest at the pre-G₁ /G₁ phase and significantly increased the concentration of cells at both early and late stage of apoptosis. In addition, it showed a higher safety profile on normal MCF-10A cells, and higher antiproliferative activity on cancer cells (IC₅₀  = 8.15 µM) in comparison to normal cells (IC₅₀  = 41.20 µM). It also revealed a fivefold higher selectivity index than erlotinib towards MCF-7 cancer cells. Docking studies were performed to rationalize the dual inhibitory activity of compound 12.

Lapatinib ditosylate rescues memory impairment in D-galactose/ovariectomized rats: Potential repositioning of an anti-cancer drug for the treatment of Alzheimer's disease

Epidermal growth factor receptor (EGFR) signaling plays a substantial role in learning and memory. The upregulation of EGFR has been embroiled in the pathophysiology of Alzheimer's disease (AD). Nevertheless, most of EGFR-tyrosine kinase inhibitors (EGFR-TKIs) have been extensively studied for non-CNS diseases such as cancer and rheumatoid arthritis. TKIs targeting-based research in neurodegenerative disorders sounds to be lagging behind those of other diseases. Hence, this study aims to explore the molecular signaling pathways and the efficacy of treatment with lapatinib ditosylate (LAP), as one of EGFR-TKIs that has not yet been investigated in AD, on cognitive decline induced by ovariectomy (OVX) with chronic administration of D-galactose (D-gal) in female Wistar albino rats. OVX rats were injected with 150 mg/kg/day D-gal ip for 8 weeks to induce AD. Administration of 100 mg/kg/day LAP p.o. for 3 weeks starting after the 8^th week of D-gal administration improved memory and debilitated histopathological alterations. LAP decreased the expression of GFAP, p-tau, and Aβ 1-42. Besides, it reduced EGFR, HER-2, TNF-α, NOX-1, GluR-II, p38 MAPK, and p-mTOR. LAP increased nitrite, and neuronal pro-survival transduction proteins; p-PI3K, p-AKT, and p-GSK-3β levels. Taken together, these findings suggest the role of LAP in ameliorating D-gal-induced AD in OVX rats via activating the pro-survival pathway; PI3K-Akt-GSK-3β, while inhibiting p-mTOR, NOX-1, and p38 MAPK pathways. Moreover, this research offered a significant opportunity to advance awareness of the repositioning of TKI anti-cancer drugs for the treatment of AD.

RNF144a induces ERK-dependent cell death under oxidative stress via downregulation of vaccinia-related kinase 3

Vaccinia-related kinase 3 (VRK3) has been reported to be a negative regulator of ERK (ERK1 and ERK2; also known as MAPK3 and MAPK1, respectively) that protects cells from persistent ERK activation and inhibits ERK-dependent apoptosis. Here we report that the E3 ubiquitin-protein ligase RNF144a promotes the degradation of VRK3 via polyubiquitylation and thus affects VRK3-mediated ERK activity. Under oxidative stress, VRK3 migrates from the nucleus to the cytoplasm, which increases its chance of interacting with RNF144a, thereby promoting the degradation of VRK3. Overexpression of RNF144a increases ERK activity via downregulation of VRK3 and promotes ERK-dependent apoptosis. In contrast, depletion of RNF144a increases the protein level of VRK3 and protects cells from excessive ERK activity. These findings suggest that VRK3 protects cells by suppressing oxidative stress-induced ERK, and that RNF144a sensitively regulates this process.

MiR-1299 Impedes the Progression of Non-Small-Cell Lung Cancer Through EGFR/PI3K/AKT Signaling Pathway

Background

Non-small-cell lung cancer (NSCLC) is one of the most malignant tumors. In which, numerous miRNAs had been reported to participate in the pathogenesis. However, the expression and function of miR-1299 in NSCLC are not clear.

Methods

To explore the roles of miR-1299 in NSCLC, we detected the levels of miR-1299 in clinical samples of NSCLC and investigated the role of miR-1299 in the regulation of the NSCLC cells proliferation, metastasis, and EMT. Luciferase reporter assay was employed to verify the target of miR-1299. Additionally, the proliferation, metastasis, and EMT of A549 and H1299 cells were analyzed after the overexpression and knockdown of miR-1299.

Results

We found that the miR-1299 expression negatively corresponded with the clinical stage and overall survival in NSCLC patients. Overexpression of miR-1299 inhibited the migration, invasion, and EMT of A549 and H1975 cells. Meanwhile, we proved that miR-1299 is the sponge of EGFR. Besides, our results suggested that miR-1299 inhibits the progression of NSCLC cells through the PI3K/Akt signal pathway.

Conclusion

We demonstrated that miR-1299 inhibits the progression of NSCLC through the EGFR/PI3K/Akt signal pathway. Therapeutic intervention targeting the miR-1299 may provide a potential strategy for the treatment of NSCLC.

Colorectal cancer (CRC) as a multifactorial disease and its causal correlations with multiple signaling pathways

Colorectal cancer (CRC) is the third most common malignancy and one of the leading causes of cancer-related death among men worldwide. CRC is a multifactor digestive pathology, which is a huge problem faced not only by clinicians but also by researchers. Importantly, a unique feature of CRC is the dysregulation of molecular signaling pathways. To date, a series of reviews have indicated that different signaling pathways are disordered and have potential as therapeutic targets in CRC. Nevertheless, an overview of the function and interaction of multiple signaling pathways in CRC is needed. Therefore, we summarized the pathways, biological functions and important interactions involved in CRC. First, we investigated the involvement of signaling pathways, including Wnt, PI3K/Akt, Hedgehog, ErbB, RHOA, Notch, BMP, Hippo, AMPK, NF-κB, MAPK and JNK. Subsequently, we discussed the biological function of these pathways in pathophysiological aspects of CRC, such as proliferation, apoptosis and metastasis. Finally, we summarized important interactions among these pathways in CRC. We believe that the interaction of these pathways could provide new strategies for the treatment of CRC.

A glance over doxorubicin based-nanotherapeutics: From proof-of-concept studies to solutions in the market

Cancer is one of the leading causes of death worldwide and, as such, efforts are being done to find new chemotherapeutic drugs or, alternatively, novel approaches for the delivery of old ones. In this scope, when used as vehicles for drugs, nanomaterials may potentially maximize the efficacy of the treatment and reduce its side effects, for example by a change in drug's pharmacokinetics, cell targeting and/or specific stimuli-responsiveness. This is the case of doxorubicin (DOX) that presents a broad spectrum of activity and is one of the most widely used chemotherapeutic drugs as first-line treatment. Indeed, DOX is a very interesting example of a drug for which several nanosized delivery systems have been developed over the years. While it is true that some of these systems are already in the market, it is also true that research on this subject remains very active and that there is a continuing search for new solutions. In this sense, this review takes the example of doxorubicin, not so much with the focus on the drug itself, but rather as a case study around which very diverse and imaginative nanotechnology approaches have emerged.

Stem extract of Tabebuia chrysantha induces apoptosis by targeting sEGFR in Ehrlich Ascites Carcinoma

ETHNOPHARMACOLOGICAL RELEVANCE

The plant Tabebuia chrysantha (Jaq.) Nicholson (Bignoniaceae) is commonly known as "Golden Goddess" in the Southern part of India and "Golden Trumpet Tree " in Central America. Stems of this plant have been traditionally used for antioxidant, anti-inflammatory, antimicrobial and anticancer actions.

AIM OF THE STUDY

To evaluate the antitumor activity of methanol extract of Tabebuia chrysantha stem (METC).

MATERIALS AND METHODS

The in vivo antitumor potential of METC against Ehrlich Ascites Carcinoma (EAC) in Swiss albino mice was assessed by evaluating tumor volume, viable and nonviable tumor cell count, tumor weight, hematological parameters, biochemical parameters, and antioxidant parameters. The in vitro antitumor potential of METC at different concentrations (100, 200, 400, 800, 1000) µg/mL has been evaluated, by using the MTT [3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide] and Trypan blue dilution assay for a period of 3 h treatment. Before that, the crude extract was pre-screened for cytotoxicity property using Brine shrimp lethality bioassay.

RESULTS

Phytoconstituents 2-Hydroxynaphthalene-1,4-dione, β-lapachone and 2-((dimethylamino)methyl)-3-methoxynaphthalene-1,4-dione were isolated from the METC. Their occurrence and structures were determined by HPLC chromatography, UV spectroscopy, and 1D and ²D NMR spectroscopies respectively. The extract showed a direct cytotoxic effect on EAC cells in a dose-dependent manner with IG₅₀ value 463.27 µg/mL in MTT assay and 443.58 µg/mL in trypan blue dilution assay. The METC (300 mg/kg) and 5-FU (30 mg/kg) exhibited significant (p < 0.001) decrease in tumor volume, tumor weight and viable cell count of EAC-treated mice. Also, hematological profile, tissue parameters such as lipid peroxidation, reduced glutathione, superoxide dismutase, and catalase were reverted to the normal levels compared to the EAC control group. The Western blotting analysis demonstrated apoptosis of carcinoma was due to inhibition of soluble epidermal growth factor receptor proteins (sEGFR) expression in the blood.

CONCLUSION

The antitumor potential of the stem extract of T chrysantha was due to naphthaquinones and polyphenol content in the crude extract and so T chrysantha could be a cytotoxic plant to control tumor growth.

Novel β-phenylacrylic acid derivatives exert anti-cancer activity by inducing Src-mediated apoptosis in wild-type KRAS colon cancer

Many stress conditions including chemotherapy treatment is known to activate Src and under certain condition Src can induce the apoptotic signal via c-Jun N-terminal kinase (JNK) activation. Here we report that the newly synthesized β-phenylacrylic acid derivatives, MHY791 and MHY1036 (MHYs), bind to epidermal growth factor receptor (EGFR) tyrosine kinase domains and function as EGFR inhibitors, having anti-cancer activities selectively in wild-type KRAS colon cancer. Mechanistically, MHYs-induced Src/JNK activation which enhanced their pro-apoptotic effects and therefore inhibition of Src by the chemical inhibitor PP2 or Src siRNA abolished the response. In addition, MHYs generated reactive oxygen species and increased ER stress, and pretreatment with antioxidant-inhibited MHY-induced ER stress, Src activation, and apoptosis. Furthermore, the irreversible EGFR inhibitor PD168393 also activated Src while the reversible EGFR inhibitor gefitinib showed the opposite effect, indicating that MHYs are the irreversible EGFR inhibitor. Collectively, Src can play a key role in apoptosis induced by the novel EGFR inhibitor MHYs, suggesting that activation of Src might prove effective in treating EGFR/wild-type KRAS colon cancer.

Down-regulation of HECTD3 by HER2 inhibition makes serous ovarian cancer cells sensitive to platinum treatment

Resistance to platinum-based chemotherapy is a major cause of treatment failure in patients with epithelial ovarian cancer and predicts a poor prognosis. Previously, we found that HECTD3 confers cancer cell resistance to apoptosis. However, the significance of HECTD3 expression in ovarian cancer and its regulatory mechanisms were unknown. Here, we found that HECTD3 depletion promotes carboplatin-induced apoptosis in both an ovarian cancer cell model and a xenograft mouse model. Moreover, high HECTD3 expression is significantly associated with poor platinum response and prognosis in ovarian cancer patients. We further demonstrated that HER2 can up-regulate HECTD3 expression through activating STAT3. Furthermore, HER2 inhibitors, such as lapatinib, down-regulate HECTD3 expression and thus promote the chemosensitivity of ovarian cancer cells to carboplatin. Lapatinib combined with carboplatin also significantly inhibits serous ovarian carcinoma growth compared with each drug alone in a xenograft mouse model. HECTD3 may be considered a promising molecular predictor of platinum chemosensitivity and prognosis for serous ovarian cancer. Through decreasing HECTD3, lapatinib possesses significantly increased anti-tumor activity when combined with carboplatin compared with each agent alone, which provides an optional therapeutic regimen for serous ovarian cancer.

Oncogenic role of rab escort protein 1 through EGFR and STAT3 pathway

Rab escort protein-1 (REP1) is linked to choroideremia (CHM), an X-linked degenerative disorder caused by mutations of the gene encoding REP1 (CHM). REP1 mutant zebrafish showed excessive cell death throughout the body, including the eyes, indicating that REP1 is critical for cell survival, a hallmark of cancer. In the present study, we found that REP1 is overexpressed in human tumor tissues from cervical, lung, and colorectal cancer patients, whereas it is expressed at relatively low levels in the normal tissue counterparts. REP1 expression was also elevated in A549 lung cancer cells and HT-29 colon cancer cells compared with BEAS-2B normal lung and CCD-18Co normal colon epithelial cells, respectively. Interestingly, short interfering RNA (siRNA)-mediated REP1 knockdown-induced growth inhibition of cancer cell lines via downregulation of EGFR and inactivation of STAT3, but had a negligible effect on normal cell lines. Moreover, overexpression of REP1 in BEAS-2B cells enhanced cell growth and anchorage-independent colony formation with little increase in EGFR level and STAT3 activation. Furthermore, REP1 knockdown effectively reduced tumor growth in a mouse xenograft model via EGFR downregulation and STAT3 inactivation in vivo. These data suggest that REP1 plays an oncogenic role, driving tumorigenicity via EGFR and STAT3 signaling, and is a potential therapeutic target to control cancers.

Clustered localization of EGFRvIII in glioblastoma cells as detected by high precision localization microscopy

For receptor tyrosine kinases supramolecular organization on the cell membrane is critical for their function. Super-resolution fluorescence microscopy techniques have offered new opportunities for the analysis of single receptor localization. Here, we analysed the cluster formation of the epidermal growth factor receptor variant III (EGFRvIII), a deletion variant which is expressed in glioblastoma. The constitutively activated variant EGFRvIII is expressed in cells with an egfr gene amplification and is thought to enhance the tumorigenic potential especially of glioblastoma cells. Due to the lack of an adequate model system, it is still unclear how endogenous EGFRvIII expression alters cellular signalling and if it is organized in clusters like the wild type receptor. We have recently described the establishment of two pairs of iso-genetic cell lines (BS153 and DKMG), displaying endogenous EGFRvIII expression or not. Using these cell lines we investigated single receptor localization of EGFRvIII by high precision localization microscopy. Cluster analysis revealed that EGFRvIII is present in clusters on the surface of the cells, with about 60% or even more receptor molecules being assembled in clusters of approximately 100 nm in diameter whereby the cluster definition was iteratively determined. The signal to signal distance may indicate dimer formation while signal quantification indicates 1 × 10⁶-5 × 10⁶ EGFRvIII molecules per cell. Altogether, these data give unique insights into the membrane surface localization of EGFRvIII in glioblastoma cells. These insights will help to unveil the function of this tumour associated receptor variant which might lead to a better understanding of glioblastoma and therefore could lead to improved therapy approaches.

HBx sensitizes hepatocellular carcinoma cells to lapatinib by up-regulating ErbB3

Poor prognosis of hepatitis B virus (HBV)-associated hepatocellular carcinoma (HCC) involves HBV X protein (HBx)-induced tumor progression. HBx also contributes to chemo-resistance via inducing the expressions of anti-apoptosis and multiple drug resistance genes. However, the impact of HBx expression on the therapeutic efficacy of various receptor tyrosine kinase inhibitors remains unknown. In this study, our data showed that HBx overexpression did not alter the cellular sensitivity of HCC cell lines to sorafenib but unexpectedly enhanced the cell death induced by EGFR family inhibitors, including gefitinib, erlotinib, and lapatinib due to ErbB3 up-regulation. Mechanistically, HBx transcriptionally up-regulates ErbB3 expression in a NF-κB dependent manner. In addition, HBx also physically interacts with ErbB2 and ErbB3 proteins and enhances the formation of ErbB2/ErbB3 heterodimeric complex. The cell viability of HBx-overexpressing cells was decreased by silencing ErbB3 expression, further revealing the pivotal role of ErbB3 in HBx-mediated cell survival. Our data suggest that HBx shifts the oncogenic addiction of HCC cells to ErbB2/ErbB3 signaling pathway via inducing ErbB3 expression and thereby enhances their sensitivity to EGFR/ErbB2 inhibitors.

Cargo binding promotes KDEL receptor clustering at the mammalian cell surface

Transmembrane receptor clustering is a ubiquitous phenomenon in pro- and eukaryotic cells to physically sense receptor/ligand interactions and subsequently translate an exogenous signal into a cellular response. Despite that receptor cluster formation has been described for a wide variety of receptors, ranging from chemotactic receptors in bacteria to growth factor and neurotransmitter receptors in mammalian cells, a mechanistic understanding of the underlying molecular processes is still puzzling. In an attempt to fill this gap we followed a combined experimental and theoretical approach by dissecting and modulating cargo binding, internalization and cellular response mediated by KDEL receptors (KDELRs) at the mammalian cell surface after interaction with a model cargo/ligand. Using a fluorescent variant of ricin toxin A chain as KDELR-ligand (eGFP-RTA^H/KDEL), we demonstrate that cargo binding induces dose-dependent receptor cluster formation at and subsequent internalization from the membrane which is associated and counteracted by anterograde and microtubule-assisted receptor transport to preferred docking sites at the plasma membrane. By means of analytical arguments and extensive numerical simulations we show that cargo-synchronized receptor transport from and to the membrane is causative for KDELR/cargo cluster formation at the mammalian cell surface.

Discrimination of driver and passenger mutations in epidermal growth factor receptor in cancer

Cancer is one of the most life-threatening diseases and mutations in several genes are the vital cause in tumorigenesis. Protein kinases play essential roles in cancer progression and specifically, epidermal growth factor receptor (EGFR) is an important target for cancer therapy. In this work, we have developed a method to classify single amino acid polymorphisms (SAPs) in EGFR into disease-causing (driver) and neutral (passenger) mutations using both sequence and structure based features of the mutation site by machine learning approaches. We compiled a set of 222 features and selected a set of 21 properties utilizing feature selection methods, for maximizing the prediction performance. In a set of 540 mutants, we obtained an overall classification accuracy of 67.8% with 10 fold cross validation using support vector machines. Further, the mutations have been grouped into four sets based on secondary structure and accessible surface area, which enhanced the overall classification accuracy to 80.2%, 81.9%, 77.9% and 75.1% for helix, strand, coil-buried and coil-exposed mutants, respectively. The method was tested with a blind dataset of 60 mutations, which showed an average accuracy of 85.4%. These accuracy levels are superior to other methods available in the literature for EGFR mutants, with an increase of more than 30%. Moreover, we have screened all possible single amino acid polymorphisms (SAPs) in EGFR and suggested the probable driver and passenger mutations, which would help in the development of mutation specific drugs for cancer treatment.

Tyrosine 1045 codon mutations in exon 27 of EGFR are infrequent in oral squamous cell carcinomas

BACKGROUND

The activation and inactivation of receptor tyrosine kinases are tightly regulated to ensure faithful replication of cells. After having transduced extracellular growth activating signals, activated EGFR is subjected to downregulation either by clathrin mediated endocytosis or c-Cbl mediated proteasome degradation depending on the ligand concentration. c-Cbl is an ubiquitin ligase which requires a phosphorylated tyrosine residue at position 1045 in the cytoplasmic domain of EGFR to interact and add ubiquitin molecules. While activating mutations in exons 19 and 21 have been associated with the development of several cancers, the status of mutations at tyrosine 1045 coding exon 27 of EGFR remain to be investigated. Consistently, defective phosphorylation at 1045 has been associated with sustained phosphorylation of EGFR in non-small lung carcinomas. Hence in the present study we investigated the genetic status of the tyrosine 1045 coding site within exon 27 of EGFR gene to explore for possible occurrence of mutations in this region, especially since no studies have addressed this issue so far.

MATERIALS AND METHODS

Tumor chromosomal DNA isolated from thirty five surgically excised oral squamous cell carcinoma tissues was subjected to PCR amplification with intronic primers flanking the tyrosine 1045 coding exon 27 of EGFR gene. The PCR amplicons were subsequently subjected to direct sequencing to elucidate the mutation status.

RESULTS

Sequence analysis identified no mutations in the tyrosine 1045 codon of EGFR in any of the thirty five samples that were analyzed.

CONCLUSIONS

The lack of identification of mutation in the tyrosine 1045 codon of EGFR suggests that mutations in this region may be relatively rare in oral squamous cell carcinomas. To the best of our knowledge, this study is the first to have explored the genetic status of exon 27 of EGFR in oral squamous cell carcinoma tissue samples.

Therapeutic resistance in cancer: microRNA regulation of EGFR signaling networks

Receptor tyrosine kinases (RTKs) such as the epidermal growth factor receptor (EGFR) regulate cellular homeostatic processes. EGFR activates downstream signaling cascades that promote tumor cell survival, proliferation and migration. Dysregulation of EGFR signaling as a consequence of overexpression, amplification and mutation of the EGFR gene occurs frequently in several types of cancers and many become dependent on EGFR signaling to maintain their malignant phenotypes. Consequently, concerted efforts have been mounted to develop therapeutic agents and strategies to effectively inhibit EGFR. However, limited therapeutic benefits to cancer patients have been derived from EGFR-targeted therapies. A well-documented obstacle to improved patient survival is the presence of EGFR-inhibitor resistant tumor cell variants within heterogeneous tumor cell masses. Here, we summarize the mechanisms by which tumors resist EGFR-targeted therapies and highlight the emerging role of microRNAs (miRs) as downstream effector molecules utilized by EGFR to promote tumor initiation, progression and that play a role in resistance to EGFR inhibitors. We also examine evidence supporting the utility of miRs as predictors of response to targeted therapies and novel therapeutic agents to circumvent EGFR-inhibitor resistance mechanisms.

Scheduling of paclitaxel and gefitinib to inhibit repopulation for optimal treatment of human cancer cells and xenografts that overexpress the epidermal growth factor receptor

PURPOSE

In clinical studies, evaluating the combination of chemotherapy and the epidermal growth factor receptor (EGFR) inhibitor gefitinib, treatments were administered concurrently, despite it being counter-intuitive to give a cytostatic agent concurrent with cycle-active chemotherapy. One strategy to enhance efficacy might be to give the agents sequentially, thus allowing selective inhibition of repopulation of cancer cells between doses of chemotherapy. Here, we evaluate the hypothesis that sequential administration might allow inhibition of repopulation by gefitinib, with tumor cells re-entering cycle to allow sensitivity to subsequent chemotherapy.

METHODS

Sequential and concurrent administration of paclitaxel and gefitinib were studied in vitro and in xenografts using EGFR over-expressing, EGFR-mutant, and EGFR wild-type human cancer cell lines. We evaluated cell cycle distribution and repopulation during treatment.

RESULTS

The sequential use of gefitinib and paclitaxel to treat EGFR over-expressing A431 cells in vitro decreased repopulation compared to chemotherapy alone, and there was greater cell kill compared to concurrent treatment. In contrast, combined treatment led to greater growth delay than use of gefitinib alone for concurrent but not for sequential treatment of mice bearing A431 xenografts; concurrent treatment had greater effects to reduce functional vasculature in the tumors. Conversely, sequential treatment led to greater growth delay than concurrent treatment of EGFR-mutant HCC-827 xenografts that are sensitive to lower doses of gefitinib.

CONCLUSIONS

These studies highlight the importance of considering effects on the cell cycle, and on the solid tumor microenvironment, including tumor vasculature, when scheduling cytostatic and cytotoxic agents in combination.

Hypoxia-inducible factor 1 alpha mediates epidermal growth factor-induced down-regulation of E-cadherin expression and cell invasion in human ovarian cancer cells

Hypoxia-inducible factor 1α (HIF-1α) regulates the transcription of a number of genes under hypoxia and other extracellular stimulations. It has been shown that E-cadherin is down-regulated by epidermal growth factor receptor (EGF) stimulation, and that cells with low E-cadherin expression are more invasive. Our recent study demonstrated a novel mechanism by which EGF down-regulates E-cadherin expression through production of hydrogen peroxide (H(2)O(2)) and the activation of p38 MAPK in human ovarian cancer cells. In this study, we were interested in examining the potential role of HIF-1α in cell invasion under normoxic conditions, specifically when cells are treated with EGF, which is known to down-regulate E-cadherin and increase invasiveness. We show that EGF treatment induces HIF-1α expression in two human ovarian cancer cell lines (SKOV3 and OVCAR5), and that this effect is diminished by treatment with a membrane-permeable H(2)O(2) scavenger, PEG-catalase. However, the induction of HIF-1α by EGF did not require the activation of p38 MAPK. Treatment with siRNA targeting HIF-1α reduces both basal and EGF-induced HIF-1α levels. Importantly, treatment with HIF-1α siRNA diminishes the up-regulation of Snail and Slug as well as the down-regulation of E-cadherin by EGF. The involvement of HIF-1α in the down-regulation of E-cadherin was confirmed with cobalt chloride (CoCl(2)), a hypoxia-mimetic reagent. Finally, we also show that EGF-induced cell invasion is attenuated by treatment with HIF-1α siRNA. This study demonstrates an important role for HIF-1α in mediating the effects of EGF on Snail, Slug and E-cadherin expression as well as invasiveness in human ovarian cancer cells.

UBE4B levels are correlated with clinical outcomes in neuroblastoma patients and with altered neuroblastoma cell proliferation and sensitivity to epidermal growth factor receptor inhibitors

BACKGROUND

The UBE4B gene, which is located on chromosome 1p36, encodes a ubiquitin ligase that interacts with hepatocyte growth factor-regulated tyrosine kinase substrate (Hrs), a protein involved in epidermal growth factor receptor (EGFR) trafficking, suggesting a link between EGFR trafficking and neuroblastoma pathogenesis. The authors analyzed the roles of UBE4B in the outcomes of patients with neuroblastoma and in neuroblastoma tumor cell proliferation, EGFR trafficking, and response to EGFR inhibition.

METHODS

The association between UBE4B expression and the survival of patients with neuroblastoma was examined using available microarray data sets. UBE4B and EGFR protein levels were measured in patient tumor samples, EGFR degradation rates were measured in neuroblastoma cell lines, and the effects of UBE4B on neuroblastoma tumor cell growth were analyzed. The effects of the EGFR inhibitor cetuximab were examined in neuroblastoma cells that expressed wild-type and mutant UBE4B.

RESULTS

Low UBE4B gene expression is associated with poor outcomes in patients with neuroblastoma. UBE4B overexpression reduced neuroblastoma tumor cell proliferation, and UBE4B expression was inversely related to EGFR expression in tumor samples. EGFR degradation rates correlated with cellular UBE4B levels. Enhanced expression of catalytically active UBE4B resulted in reduced sensitivity to EGFR inhibition.

CONCLUSIONS

The current study demonstrates associations between UBE4B expression and the outcomes of patients with neuroblastoma and between UBE4B and EGFR expression in neuroblastoma tumor samples. Moreover, levels of UBE4B influence neuroblastoma tumor cell proliferation, EGFR degradation, and response to EGFR inhibition. These results suggest UBE4B-mediated growth factor receptor trafficking may contribute to the poor prognosis of patients who have neuroblastoma tumors with 1p36 deletions and that UBE4B expression may be a marker that can predict responses of neuroblastoma tumors to treatment.

Nuclisome--targeting the tumor cell nucleus

The Nuclisome concept builds on a novel two-step targeting strategy with the aim to deliver short-range Auger-electron-emitting radionuclides to nuclear DNA of tumor cells. The concept is based on the use of Nuclisome-particles, i.e., tumor-targeted PEG-stabilized liposomes loaded with a unique DNA-intercalating compound that enables specific and effective delivery of radionuclides to DNA. The specific and potent two-step targeting leads to eradication of tumor cells while toxicity to normal organs is reduced to a minimum. Results of in vitro and in vivo studies point towards the Nuclisome concept as a promising strategy for the treatment of small tumor masses and, in particular, for the elimination of spread single cells and micrometastases.

Targeting the epidermal growth factor receptor in solid tumor malignancies

The epidermal growth factor receptor (EGFR) is over-expressed, as well as mutated, in many types of cancers. In particular, the EGFR variant type III mutant (EGFRvIII) has attracted much attention as it is frequently and exclusively found on many tumor cells, and hence both EGFR and EGFRvIII have been proposed as valid targets in many cancer therapy settings. Different strategies have been developed in order to either inhibit EGFR/EGFRvIII activity or to ablate EGFR/EGFRvIII-positive tumor cells. Drugs that inhibit these receptors include monoclonal antibodies (mAbs) that bind to the extracellular part of EGFR, blocking the binding sites for the EGFR ligands, and intracellular tyrosine kinase inhibitors (TKIs) that block the ATP binding site of the tyrosine kinase domain. Besides an EGFRvIII-targeted vaccine, conjugated anti-EGFR mAbs have been used in different settings to deliver lethal agents to the EGFR/EGFRvIII-positive cells; among these are radio-labelled mAbs and immunotoxins. This article reviews the current status and efficacy of EGFR/EGFRvIII-targeted therapies.

Stem cells of the human epidermis and their niche: composition and function in epidermal regeneration and carcinogenesis

Skin, as the largest organ, has long been subject of excellent and pioneering studies on stem cells and their role in tissue regulation and tumor formation. In particular, intensive research on mouse skin, and here especially the hair follicle, has largely extended our knowledge. Surprisingly, human skin, although the most easily accessible tissue in man, is far less conceived with regard to its stem cells and their specific environment (the niche). In consequence, these features are as yet only insufficiently defined and it still has to be elucidated how insights in cutaneous stem cell biology gained in mice can be extrapolated to humans. In the last few years, human model systems such as humanized mice or in vitro organotypic cultures that support maintenance or reconstruction of human skin and long-term epidermal regeneration have been developed. These models allow lineage tracing experiments and can be modified by adopting genetically manipulated cell types. Accordingly, they represent proper tools for human stem cell research and will clearly help to improve our still incomplete understanding. Like normal skin, the non-melanoma skin cancers and their respective tumors have gained considerable interest in basic as well as in clinical research. Being the most frequent human tumors globally, basal cell carcinomas and cutaneous squamous cell carcinomas (SCCs) continue to increase in incidence and specifically SCCs predominate in immunosuppressed transplant recipients. This review intends to compile the present knowledge on keratinocyte stem cells and their niches in normal skin and skin carcinomas with a special focus on the human situation. In particular, the role of the microenvironment, the niche, is emphasized, promoting our view of the decisive importance of the niche as a key regulatory element for controlling position, fate and regenerative potential of the stem cell population both in healthy skin and in carcinomas.

Integrin β1 mediates epithelial growth factor-induced invasion in human ovarian cancer cells

Integrins function as cell-extracellular matrix adhesion proteins and have been implicated in tumor progression. In ovarian tumors, elevated integrin β1 expression correlates with high clinical stage and poor patient survival. In this study, we report that EGF treatment up-regulated integrin β1 mRNA and protein levels in ovarian cancer cells. Moreover, pharmacological inhibition of MEK totally abolished EGF-induced integrin β1 up-regulation and cell invasion suggesting that MAPK/ERK signaling is required for EGF-induced integrin β1 up-regulation and cell invasion. Furthermore, we found that knockdown of integrin β1 expression reduced the intrinsic invasiveness of ovarian cancer cells and the EGF-induced cell invasion. Finally, we found that overexpression of integrin β1 was sufficient to promote ovarian cancer cell invasion. This study demonstrates that integrin β1 mediates EGF-induced cell invasion in ovarian cancer.

EGFR inhibitor enhances cisplatin sensitivity of human glioma cells

Epidermal growth factor receptor (EGFR) is found to express at high levels in a variety of solid tumors including gliomas. This study was to examine the effect of an EGFR-tyrosine kinase inhibitor (AG1478) alone or in combination with cisplatin (CDDP) on the growth of glioma cells (U87). U87 glioma cells were treated with AG1478 (10 μmol/L) or CDDP (25 μmol/L) as a single agent or in combination for 24 or 48 h. The expression of EGFR and the components in its downstream signaling pathway [extracellular signal-regulated kinase (ERK), protein kinase B (AKT)] in U87 glioma cells was detected by Western blotting. Cell growth, cell cycle distribution and cell apoptosis were determined by MTT method and flow cytometry, respectively. The results showed that CDDP could induce the activation of EGFR and the components in its downstream signaling pathways in a concentration-dependent manner. The combined treatment of AG1478 with CDDP could inhibit the proliferation of U87 glioma cells, arrest the cell cycle and promote cell apoptosis. In the EGFR signaling pathway, AG1478 decreased the phosphorylation of ERK, AKT and EGFR in U87 glioma cells. It was concluded that the combined treatment of AG1478 and CDDP may exert synergistic inhibitory effects on the growth of glioma cells by suppressing the activities of EGFR, AKT and ERK.

Molecular biology of adenoid cystic carcinoma

BACKGROUND

Adenoid cystic carcinoma (ACC) is an unusual salivary gland malignancy that remains poorly understood. Standard treatment, including surgery with postoperative radiation therapy, has attained reasonable local control rates, but the propensity for distant metastases has limited any improvement in survival over time. Our understanding of the molecular mechanisms driving ACC is quite rudimentary, due to the infrequent nature of its occurrence.

METHODS

An extensive literature review was performed on salivary gland ACCs and basic science research findings.

RESULTS

This review highlights many findings that are emerging about the carcinogenesis of ACC including cytogenetics, tumor suppressor genes, oncogenes, epigenetic alterations, mitochondrial alterations, and biomarker studies.

CONCLUSION

Although there have been many discoveries, much still remains unknown about this rare malignancy. © 2011 Wiley Periodicals, Inc. Head Neck, 2011.

Design and synthesis of a series of novel bisquinazoline glycosides as epidermal growth factor receptor inhibitors

A new series of potential epidermal growth factor receptor inhibitors possessing bisquinazoline and saccharide moieties were designed and synthesized. The biological results demonstrated that the synthetic derivatives significantly inhibited epidermal growth factor receptor enzymatic activity in vitro. Of them, compound 14b showed the highest inhibitory rate toward epidermal growth factor receptor protein tyrosine kinase (81.36%) at a concentration of 1 μM. Further molecular simulation predicted that 14b offered its saccharide moieties hydrogen bonding to ATP-binding pocket.

In vitro evaluation and biodistribution of HER2-targeted liposomes loaded with an (125)I-labelled DNA-intercalator

BACKGROUND

Increasing attention is currently focussed on the issue of finding strategies for the delivery of Auger-electron-emitting radionuclides into tumor cell nuclei.

PURPOSE

In this study, we investigated tumor-cell uptake and cell-killing ability in vitro as well as in vivo biodistribution of an (125)I-labelled anthracycline derivative administered by means of HER2-targeted liposomes.

METHODS

Anthracycline derivative Comp1 was radiolabelled with Auger-emitting (125)I and encapsulated in liposomes (DSPC:Chol:DSPE-PEG) using pH-gradient loading. Single-chain fragment F5 was anchored to the liposomes as targeting device for HER2. Uptake and specificity of (125)I-Comp1 delivered via targeting and non-targeting liposomes were analysed in cultured HER2-overexpressing cells. Cell-killing efficacy was evaluated in SKOV3 cells and biodistribution for up to 48 h was studied after intraperitoneal injection in tumor-bearing female BALB/c nu/nu mice.

RESULTS

(125)I-Comp1 was specifically taken up by the cultured cells when administered by means of HER2-targeted liposomes and a clear dose-effect correlation in survival of cells was seen with increasing specific activity. The biodistribution studies revealed that (125)I-Comp1 accumulated in tumors when distributed using HER2-targeted liposomes and that this effect was absent when using non-targeting liposomes.

CONCLUSION

The HER2-targeted liposomes possess the properties needed to bring about tumor-specific delivery and therapeutic effect of (125)I-Comp1.

Inhibition of mTOR by temsirolimus contributes to prolonged survival of mice with pleural dissemination of non-small-cell lung cancer cells

Temsirolimus (CCI-779), a recently synthesized analogue of rapamycin, specifically inhibits mTOR and has been approved for clinical use in renal cell carcinoma. Recent reports have indicated the growth inhibitory effect of temsirolimus in some cancers including non-small-cell lung carcinoma (NSCLC). In this study, we aimed to explore the potential therapeutic use of temsirolimus as a treatment for NSCLC. Using cultured NSCLC cells (A549, H1299, and H358), we determined the effect of temsirolimus on cell proliferation and its antitumor effects on subcutaneous tumors, as well as its contribution to the survival of mice having pleural dissemination of cancer cells, mimicking advanced NSCLC. Temsirolimus suppressed proliferation of NSCLC cells in a dose-dependent manner, with an IC(50) of <1 nM. Western blot analysis revealed that temsirolimus treatment specifically inhibited the phosphorylation of mTOR and its downstream effectors in 1 h, accompanied by an increased cell population in the G(0) /G(1) phase, but according to flow cytometry, the cell population did not increase in the sub-G(0) phase. When NSCLC subcutaneous tumor-bearing mice were treated with temsirolimus, tumor volume was significantly reduced (tumor volume on day 35: vehicle vs temsirolimus = 1239 vs 698 cm(3) ; P < 0.05). Furthermore, prolonged survival was observed in pleural disseminated tumor-bearing mice with temsirolimus treatment (median survival: vehicle vs temsirolimus = 53.5 vs 72.5 days; P < 0.05). These results suggest that temsirolimus could be useful for NSCLC treatment, due to its antiproliferative effect, and could be a potential treatment for advanced NSCLC, giving prolonged survival.

Ubiquitously expressed hematological and neurological expressed 1 downregulates Akt-mediated GSK3β signaling, and its knockdown results in deregulated G2/M transition in prostate cells

As the molecular mechanism of β-catenin deregulation is not well understood, and stabilized β-catenin is known to translocate into the nucleus and activate genes for proliferation, a novel regulatory factor, hematological and neurological expressed 1 (HN1), for Akt-GSK3β-β-catenin axis is reported here. In our studies, HN1 gene structure was characterized. HN1 expression was found to be epidermal growth factor-responsive in PC-3 cells, and protein expression was also upregulated in PC-3 and LNCaP but not in DU145 cells. Additionally, HN1 was found to be downregulated by the specific AKT inhibitor wortmannin but not with PI3K or MAPK inhibitors, LY294002 and PD98059, respectively, in PC-3 and MCF-7 cells. Further, siRNA-mediated knockdown of HN1 resulted in considerable increase in Akt((S473)) and GSK3β((S9),(Y216)) phosphorylations; moreover, subsequent accumulation of β-catenin, increase in c-myc expression, and nuclear accumulation of cyclin D1 were observed in PC-3 cells. Knockdown of HN1 also resulted in prolongation of G(1) phase in cell cycle, increasing tetraploidy, presumably because of cells escaping from abnormal mitosis in PC-3 cells. Consistently, overexpression of HN1 reversed the cell-cycle-specific observations, resulted in accumulation of cells in G(2)/M, and reduced the proliferation rate, which were investigated using flow cytometry and methylthiazol tetrazolium assays. As activating mutations of β-catenin have been demonstrated in late-stage tumors, and β-catenin stabilization was correlated with poor prognosis in previous reports, epidermal growth factor-upregulated HN1 expression might have a role in deregulating the AKT-GSK3β((S9))-mediated signaling as a novel compensating mechanism.

A multicenter phase II trial of single-agent cetuximab in advanced esophageal and gastric adenocarcinoma

BACKGROUND

Epidermal growth factor receptor (EGFR) is overexpressed in a significant proportion of esophageal and gastric carcinomas. Although previous studies have examined tyrosine kinase inhibitors of EGFR, there remains limited data regarding the role of EGFR-directed monoclonal antibody therapy in these malignancies. We carried out a multi-institutional phase II study of cetuximab, a monoclonal antibody against EGFR, in patients with unresectable or metastatic esophageal or gastric adenocarcinoma.

PATIENTS AND METHODS

Thirty-five patients with previously treated metastatic esophageal or gastric adenocarcinoma were treated with weekly cetuximab, at an initial dose of 400 mg/m(2) followed by weekly infusions at 250 mg/m(2). Patients were followed for toxicity, treatment response, and survival.

RESULTS

Treatment with cetuximab was well tolerated; no patients were taken off study due to drug-related adverse events. One (3%) partial treatment response was noted. Two (6%) patients had stable disease after 2 months of treatment. Median progression-free survival and overall survival were 1.6 and 3.1 months, respectively.

CONCLUSION

Although well tolerated, cetuximab administered as a single agent had minimal clinical activity in patients with metastatic esophageal and gastric adenocarcinoma. Ongoing studies of EGFR inhibitors in combination with other agents may define a role for these agents in the treatment of esophageal and gastric cancer.

TGFβ and EGF synergistically induce a more invasive phenotype of epithelial ovarian cancer cells

The epithelial-mesenchymal transition (EMT) is associated with progression and metastasis of epithelial ovarian cancer (EOC). Snail and Slug (two members of the Snail family of transcription factors) down-regulate the expression of the adhesion molecule E-cadherin and thus function as positive regulators of EMT. Their expression is associated with a more invasive phenotype of EOC. However, how their expression in EOC cells is regulated needs to be further defined. Here, we show that transforming growth factor β (TGFβ) and epidermal growth factor (EGF) synergistically induce the expression of Slug and Snail at both mRNA and protein levels in an EOC cell line OVCA429 cells. Using specific chemical inhibitors, we demonstrate that Slug and Snail expression induced by TGFβ is mediated by TGFβ/ALK5 pathway, and EGF-induced expression of Slug and Snail is MEK1/2-dependent. Interestingly, TGFβ-induced Slug expression is also MEK1/2-dependent. Further, we demonstrate that combined TGFβ and EGF stimulation is more potent than either alone in repressing the expression of E-cadherin. Functionally, combined stimulation of TGFβ and EGF enhances the mobility of OVCA429 cells and induces the production of MMP2 by OVCA429 cells more potently than either alone. Taken together, our data demonstrate that TGFβ and EGF signaling pathways synergistically induce EMT and render EOC cells a more invasive phenotype.

Transcriptional profiling of ErbB signalling in mammary luminal epithelial cells--interplay of ErbB and IGF1 signalling through IGFBP3 regulation

BACKGROUND

Members of the ErbB family of growth factor receptors are intricately linked with epithelial cell biology, development and tumourigenesis; however, the mechanisms involved in their downstream signalling are poorly understood. Indeed, it is unclear how signal specificity is achieved and the relative contribution each receptor has to specific gene expression.

METHODS

Gene expression profiling of a human mammary luminal epithelial cell model of ErbB2-overexpression was carried out using cDNA microarrays with a common RNA reference approach to examine long-term overlapping and differential responses to EGF and heregulin beta1 treatment in the context of ErbB2 overexpression. Altered gene expression was validated using quantitative real time PCR and/or immunoblotting. One gene of interest was targeted for further characterisation, where the effects of siRNA-mediated silencing on IGF1-dependent signalling and cellular phenotype were examined and compared to the effects of loss of ErbB2 expression.

RESULTS

775 genes were differentially expressed and clustered in terms of their growth factor responsiveness. As well as identifying uncharacterized genes as novel targets of ErbB2-dependent signalling, ErbB2 overexpression augmented the induction of multiple genes involved in proliferation (e.g. MYC, MAP2K1, MAP2K3), autocrine growth factor signalling (VEGF, PDGF) and adhesion/cytoskeletal regulation (ZYX, THBS1, VCL, CNN3, ITGA2, ITGA3, NEDD9, TAGLN), linking them to the hyper-poliferative and altered adhesive phenotype of the ErbB2-overexpressing cells. We also report ErbB2-dependent down-regulation of multiple interferon-stimulated genes that may permit ErbB2-overexpressing cells to resist the anti-proliferative action of interferons. Finally, IGFBP3 was unique in its pattern of regulation and we further investigated a possible role for IGFBP3 down-regulation in ErbB2-dependent transformation through suppressed IGF1 signalling. We show that IGF1-dependent signalling and proliferation were enhanced in ErbB2-overexpressing cells, whilst loss of ErbB2 expression by siRNA silencing reduced IGF1 signalling. Furthermore, IGFBP3 knockdown resulted in basal ERK and Akt activation in luminal epithelial cells and increased invasiveness and anchorage-independent colony formation in SKBR3 cells.

CONCLUSIONS

These data show IGFBP3 as a negative regulator of transformation and that its down-regulation enhances IGF1-dependent signalling. They also show that ErbB2 can up-regulate IGF1-dependent signalling, possibly via the regulated expression of IGFBP3.

Glioma growth inhibition by neurostatin and O-But GD1b

In spite of their low incidence, central nervous system tumors have elevated morbidity and mortality, being responsible for 2.3% of total cancer deaths. The ganglioside O-acetylated GD1b (O-Ac GD1b; neurostatin), present in the mammalian brain, and the semi-synthetic O-butyrylated GD1b (O-But GD1b) are potent glioma proliferation inhibitors, appearing as possible candidates for the treatment of nervous system tumors. Tumoral cell division inhibitory activity in culture correlated with growth inhibition of glioma xenotransplants in Foxn1(nu) nude mice and intracranial glioma allotransplants. Both O-Ac GD1b and O-But GD1b inhibited in vivo cell proliferation, induced cell cycle arrest, and potentiated immune cell response to the tumor. Furthermore, the increased stability of the butyrylated compound (O-But GD1b) enhanced its activity with respect to the acetylated ganglioside (neurostatin). These results are the first report of the antitumoral activity of neurostatin and a neurostatin-like compound in vivo and indicate that semi-synthetic O-acetylated and O-butyrylated gangliosides are potent antitumoral compounds that should be considered in strategies for brain tumor treatment.

Hydrogen peroxide mediates EGF-induced down-regulation of E-cadherin expression via p38 MAPK and snail in human ovarian cancer cells

In ovarian cancer, it has been shown that E-cadherin is down-regulated by epidermal growth factor (EGF) receptor (EGFR) activation, and that cells with low E-cadherin expression are particularly invasive. Although it is generally believed that reactive oxygen species play important roles in intracellular signal transduction, the role of reactive oxygen species in EGF-mediated reductions in E-cadherin remains to be elucidated. In this study, we show that EGF treatment down-regulated E-cadherin by up-regulating its transcriptional repressors, Snail and Slug, in human ovarian cancer cells. Using 5-(and-6)-chloromethyl-2',7'-dichlorodihydrofluorescein diacetate acetyl ester staining, we found that intracellular hydrogen peroxide (H(2)O(2)) production was increased in EGF-treated cells and could be inhibited by treatment with an EGFR inhibitor, AG1478, or an H(2)O(2) scavenger, polyethylene glycol (PEG)-catalase. In addition, PEG-catalase diminished EGF-induced p38 MAPK, but not ERK1/2 or c-Jun N-terminal kinase, phosphorylation. PEG-catalase and the p38 MAPK inhibitor SB203580 abolished EGF-induced Snail, but not Slug, expression and E-cadherin down-regulation. Furthermore, the involvement of p38 MAPK in the down-regulation of E-cadherin was confirmed using specific p38alpha MAPK small interfering RNA. Finally, we also show that EGF-induced cell invasion was abolished by treatment with PEG-catalase and SB203580, as well as p38alpha MAPK small interfering RNA, and that forced expression of E-cadherin diminished intrinsic invasiveness as well as EGF-induced cell invasion. This study demonstrates a novel mechanism in which EGF down-regulates E-cadherin expression through production of H(2)O(2), activation of p38 MAPK, and up-regulation of Snail in human ovarian cancer cells.

Evaluation of folate-PAMAM for the delivery of antisense oligonucleotides to rat C6 glioma cells in vitro and in vivo

In the current study, we evaluated the efficiency of folate-polyamidoamine dendrimers conjugates (FA-PAMAM) for the in situ delivery of therapeutic antisense oligonucleotides (ASODN) that could inhibit the growth of C6 glioma cells. Folic acid was coupled to the surface amino groups of G5-PAMAM dendrimer (G5D) through a 1-[3-(dimethylamino)propyl]-3-ethylcarbodiimide bond, and ASODNs corresponding to rat epidermal growth factor receptor (EGFR) were then complexed with FA-PAMAM. At an ASODN to PAMAM ratio of 16:1, agarose electrophoresis indicated that antisense oligonucleotides were completely complexed with PAMAM or FA-PAMAM. The ASODN transfection rates mediated by FA-PAMAM and PAMAM were superior to oligofectamine, resulting in greater suppression of EGFR expression and glioma cell growth. Stereotactic injection of EGFR ASODN:FA-PAMAM complexes into established rat C6 intracranial gliomas resulted in greater suppression of tumor growth and longer survival time of tumor-bearing rats compared with PAMAM and oligofectamine-mediated EGFR-ASODN therapy. The current study demonstrates the suitability of folate-PAMAM dendrimer conjugates for efficient EGFR ASODN delivery into glioma cells, wherein they release the ASODN from the FA-PAMAM to knock down EGFR expression in C6 glioma cells, both in vitro and in vivo. FA-PAMAM may thus represent a novel delivery system for short oligonucleotides in glioma-targeted therapy.

Integrating molecular diagnostics into anticancer drug discovery

In the 1990s, the breast cancer drug trastuzumab (Herceptin; Genentech/Roche)--an antibody specific for human epidermal growth factor receptor 2 (HER2; also known as ERBB2)--was approved based on trials in which HER2 expression levels were used to select patients in clinical trials. This provided support for analogous efforts for drugs that target the epidermal growth factor receptor (EGFR). However, the development of these drugs, such as cetuximab (Erbitux; Bristol-Myers Squibb/Lilly) and gefitinib (Iressa; AstraZeneca), has revealed that EGFR expression is an insufficient and unreliable biomarker to select patients for EGFR-targeted therapies in both lung and colon cancer. Indeed, evidence on patient populations that are likely to respond to such therapies, on the basis of specific mutations in proteins of the targeted pathway, has only recently been clinically validated and incorporated into some of the drug labels. This article highlights lessons learned from the development of the first drugs targeting the EGFR family and discusses strategies to decrease the risk of failure in clinical development by more effectively integrating molecular diagnostics into anticancer drug discovery.

Epidermal growth factor receptor signaling in nonsmall cell lung cancer

Epidermal growth factor is a 170-kd protein that binds to a specific tyrosine kinase receptor, epidermal growth factor receptor (EGFR), on the cell surface. EGFR function is dysregulated in various malignancies including nonsmall cell lung cancer (NSCLC) leading to activation of several signal transduction pathways including K-RAS, PIK3, and STAT3 and STAT5, that promote cell cycle progression, proliferation, invasion, angiogenesis, and inhibit apoptosis. EGFR overexpression is seen in a majority of cases of NSCLC, but its prognostic role is controversial. EGFR inhibitors currently undergoing clinical trials in NSCLC include monoclonal antibodies or small molecule tyrosine kinase inhibitors. The only EGFR inhibitor currently approved for the treatment of NSCLC is erlotinib, a small molecule tyrosine kinase inhibitor. Although women, nonsmokers, patients with adenocarcinoma and patients with Asian ethnicity seem to have better outcomes with erlotinib, the factors predictive for response to these agents are currently the focus of investigation.