Ahad A. Sadiq

MET As a Possible Target for Non–Small-Cell Lung Cancer

Lung cancer is a heterogeneous group of disorders that is now being subdivided into molecular subtypes with dedicated targeted therapies. The MET receptor tyrosine kinase has been identified as aberrantly overexpressed, potentially having activating mutations, and amplified in certain subsets of lung cancers. The ligand hepatocyte growth factor (HGF) can also be overexpressed in lung cancer or expressed in stroma, and both the MET receptor and the HGF ligand can be targets for therapeutics, especially in lung cancer. Activation of MET leads to a plethora of biochemical and biologic changes both in normal and cancerous cells. Preclinically, it has been shown that silencing or inactivating MET leads to decreased viability of cancer cells. There are a number of compounds against MET/HGF in clinical trials that have been shown to be active in lung cancers. This review will summarize the biology of MET as well as its therapeutic inhibition in lung cancer.

Activated 4E-BP1 represses tumourigenesis and IGF-I-mediated activation of the eIF4F complex in mesothelioma

Background:Insulin-like growth factor (IGF)-I signalling stimulates proliferation, survival, and invasion in malignant mesothelioma and other tumour types. Studies have found that tumourigenesis is linked to dysregulation of cap-dependent protein translation.Methods:The effect of IGF stimulation on cap-mediated translation activation in mesothelioma cell lines was studied using binding assays to a synthetic 7-methyl GTP-cap analogue. In addition, cap-mediated translation was genetically repressed in these cells with a dominant active motive of 4E-BP1.Results:In most mesothelioma cell lines, IGF-I stimulation resulted in a hyperphosphorylation-mediated inactivation of 4E-BP1 compared with that in normal mesothelial cells. An inhibitor of Akt diminished IGF-I-mediated phosphorylation of 4E-BP1, whereas inhibiting MAPK signalling had no such effect. IGF-I stimulation resulted in the activation of the cap-mediated translation complex as indicated by an increased eIF4G/eIF4E ratio in cap-affinity assays. Akt inhibition reversed the eIF4G/eIF4E ratio. Mesothelioma cells transfected with an activated 4E-BP1 protein (4E-BP1A37/A46) were resistant to IGF-I-mediated growth, motility, and colony formation. In a murine xenograft model, mesothelioma cells expressing the dominant active 4E-BP1A37/A46 repressor protein showed abrogated tumourigenicity compared with control tumours.Conclusion:IGF-I signalling in mesothelioma cells drives cell proliferation, motility, and tumourigenesis through its ability to activate cap-mediated protein translation complex through PI3K/Akt/mTOR signalling.

Antisense oligonucleotide targeting eukaryotic translation initiation factor 4E reduces growth and enhances chemosensitivity of non-small-cell lung cancer cells.

Elevated levels of eukaryotic translation initiation factor 4E (eIF4E) enhance translation of many malignancy-related proteins, such as vascular endothelial growth factor (VEGF), c-Myc and osteopontin. In non-small-cell lung cancer (NSCLC), levels of eIF4E are significantly increased compared with normal lung tissue. Here, we used an antisense oligonucleotide (ASO) to inhibit the expression of eIF4E in NSCLC cell lines. eIF4E levels were significantly reduced in a dose-dependent manner in NSCLC cells treated with eIF4E-specific ASO (4EASO) compared with control ASO. Treatment of NSCLC cells with the 4EASO resulted in decreased cap-dependent complex formation, decreased cell proliferation and increased sensitivity to gemcitabine. At the molecular level, repression of eIF4E with ASO resulted in decreased expression of the oncogenic proteins VEGF, c-Myc and osteopontin, whereas expression of β-actin was unaffected. Based on these findings, we conclude that eIF4E-silencing therapy alone or in conjunction with chemotherapy represents a promising approach deserving of further investigation in future NSCLC clinical trials.

Measles vaccine strains for virotherapy of non-small-cell lung carcinoma

Introduction: Oncolytic virus therapy is a promising therapy for numerous tumor types. Edmonston-strain measles virus (MV) has been tested in clinical trials for ovarian cancer, glioma, and myeloma. Therefore, the antitumor activity of MV against non–small-cell lung cancer (NSCLC) was assessed. Methods: Human NSCLC cells and immortalized lung epithelial cell lines, Beas2B, were infected with either MV-producing green fluorescent protein or MV-producing carcinoembryonic antigen. Cells were assessed for viability, induction of apoptosis by caspase and poly-ADP ribose polymerase cleavage, and for viral transgene production. The dependency of MV entry on CD46 and nectin-4 were determined using blocking antibodies. The role of host translational activity on viral replication was assessed by overexpression of eIF4E and translation inhibition. Antitumor activity was assessed by measuring treated NSCLC xenografts from flanks of nude mice. Results: MV infection of NSCLC cells results in potent cell killing in most of the cell lines compared with immortalized Beas2B cells and induces apoptosis. MV infection was prevented by blocking of CD46, however independent of nectin-4 blockade. Tumor weights are diminished after intratumoral injections of MV-producing carcinoembryonic antigen in one of two cell lines and result in detectable viral transgene in serum of mice. Conclusions: These data indicate that MV is oncolytic for human NSCLC and this was independent of nectin-4 expression. Dysregulated protein translational machinery may play a role in determining tumor tropism in NSCLC. MV combined with gemcitabine could be explored further as chemovirotherapy for NSCLC.

Resistance to EGFR-TKI Can Be Mediated through Multiple Signaling Pathways Converging upon Cap-Dependent Translation in EGFR-Wild Type NSCLC

Introduction: For the majority of patients with non–small-cell lung cancer (NSCLC), response to epidermal growth factor receptor tyrosine kinase inhibitors (EGFR-TKIs) is suboptimal. In models of acquired resistance to EGFR-TKI, activation of Akt phosphorylation is frequently observed. Because Akt activation results in downstream initiation of cap-dependent protein translation, we hypothesized that a strategy of targeting cap-dependent translation in combination with erlotinib might enhance therapy. Methods: NSCLC cells that are wild type for EGFR were assayed for sensitivity to erlotinib. Serum-starved NSCLC cells were assayed for EGFR signaling and downstream pathway activation by immunoblot after stimulation with epidermal growth factor. EGFR signaling and signaling mediators of cap-dependent translation were assayed by immunoblot under serum-replete conditions 24 hours after treatment with erlotinib. Finally, combination treatment with erlotinib and two different cap-dependent translation inhibitors were done to assess the effect on cell viability. Results: EGFR signaling is coupled to activation of cap-dependent translation in EGFR wild-type cells. Erlotinib inhibits EGFR phosphorylation in EGFR-TKI resistant cells, however, results in activation of downstream signaling molecules including Akt and extracellular regulated kinase, ERK 1/2, resulting in maintenance of eukaryotic initiation factor 4F (eIF4F) activation. eIF4F cap-complex formation is maintained in erlotinib-resistant cells, but not in erlotinib-sensitive cells. Finally, using an antisense oligonucleotide against eukaryotic translation initiation factor 4E and a small-molecule inhibitor to disrupt eIF4F formation, we show that cap-dependent translation inhibition can enhance sensitivity to erlotinib. Conclusion: The results of these studies support further clinical development of translation inhibitors for treatment of NSCLC in combination with erlotinib.

Inhibition of MET Receptor Tyrosine Kinase and Its Ligand Hepatocyte Growth Factor

Target-based therapeutic development has significantly changed cancer treatment and has generated new sense of optimism. Cancers that contain multiple genetic and epigenetic abnormalities remain addicted to one or few genes for their malignant phenotype and cell survival. Inhibition of these abnormalities via monoclonal antibodies (mAbs) and small-molecule inhibitors (SMIs) have brought about new hope in NSCLC. MET gene was initially discovered in the laboratory of George Vande Woude as part of a transforming fusion gene between transforming promoter region (TPR) and MET which was derived from a chromosomal translocation after treatment with N-methyl-N-nitro-N-nitrosoguanidine. 1 MET is located on chromosome 7, encodes for a single precursor which is post-transcriptionally digested, forming an extracellular -chain and a transmembrane s-chain linked by disulfide bonds. The ligand for MET is hepatocyte growth factor (HGF)/Scatter Factor (SF), which is synthesized as a single inactive polypeptide chain (pro-HGF/SF) and cleaved to an active, disulfide-linked dimer by serine proteases including uPA, tPA, and then binds to the MET Sema domain. 2 Ligation of the MET receptor by HGF leads to receptor dimerization and activation of its intrinsic tyrosine kinase and further autophosphorylation or phosphorylation of downstream intermediates and activation of signaling pathways. MET can be activated by mutations, autocrine/paracrine growth, overexpression by gene amplification, or decreased degradation. Germline and somatic MET gene mutations have been reported in hereditary and sporadic papillary renal cell cancers. 3‐5 Both MET gene mutations and amplifications have now been reported in other cancers, although at low frequencies but as genetic predictors of therapeutic sensitivity. 6 Expression of MET and phosphoMET has been studied in lung cancer, and recently it was shown that 40% of lung cancer tissues overexpressed MET. 7 Summary of Presentations MET as a therapeutic target in NSCLC Dr. Robert C. Doebele discussed some of the key background points surrounding MET inhibition in NSCLC. He noted that survival in NSCLC patients with 5 copies/cell is worse than those with less than 5 copies/cell and that MET gene amplification leads to EGFR tyrosine kinase resistance in EGFR mutant patients.8 Anti-HGF Abs, anti-MET Abs, and small-molecule MET TKI inhibitors are all in various stages of development, and predictive biomarkers for MET inhibitors will be important to elucidate for future trials and treatment decisions.

Utilisation of a thoracic oncology database to capture radiological and pathological images for evaluation of response to chemotherapy in patients with malignant pleural mesothelioma

Objective An area of need in cancer informatics is the ability to store images in a comprehensive database as part of translational cancer research. To meet this need, we have implemented a novel tandem database infrastructure that facilitates image storage and utilisation. Background We had previously implemented the Thoracic Oncology Program Database Project (TOPDP) database for our translational cancer research needs. While useful for many research endeavours, it is unable to store images, hence our need to implement an imaging database which could communicate easily with the TOPDP database. Methods The Thoracic Oncology Research Program (TORP) imaging database was designed using the Research Electronic Data Capture (REDCap) platform, which was developed by Vanderbilt University. To demonstrate proof of principle and evaluate utility, we performed a retrospective investigation into tumour response for malignant pleural mesothelioma (MPM) patients treated at the University of Chicago Medical Center with either of two analogous chemotherapy regimens and consented to at least one of two UCMC IRB protocols, 9571 and 13473A. Results A cohort of 22 MPM patients was identified using clinical data in the TOPDP database. After measurements were acquired, two representative CT images and 0–35 histological images per patient were successfully stored in the TORP database, along with clinical and demographic data. Discussion We implemented the TORP imaging database to be used in conjunction with our comprehensive TOPDP database. While it requires an additional effort to use two databases, our database infrastructure facilitates more comprehensive translational research. Conclusions The investigation described herein demonstrates the successful implementation of this novel tandem imaging database infrastructure, as well as the potential utility of investigations enabled by it. The data model presented here can be utilised as the basis for further development of other larger, more streamlined databases in the future.

Cap-dependent translational control of oncolytic measles virus infection in malignant mesothelioma

Malignant mesothelioma has a poor prognosis for which there remains an urgent need for successful treatment approaches. Infection with the Edmonston vaccine strain (MV-Edm) derivative of measles virus results in lysis of cancer cells and has been tested in clinical trials for numerous tumor types including mesothelioma. Many factors play a role in MV-Edm tumor cell selectivity and cytopathic activity while also sparing non-cancerous cells. The MV-Edm receptor CD46 (cluster of differentiation 46) was demonstrated to be significantly higher in mesothelioma cells than in control cells. In contrast, mesothelioma cells are not reliant upon the alternative MV-Edm receptor nectin-4 for entry. MV-Edm treatment of mesothelioma reduced cell viability and also invoked apoptotic cell death. Forced expression of eIF4E or translation stimulation following IGF-I (insulin-like growth factor 1) exposure strengthened the potency of measles virus oncolytic activity. It was also shown that repression of cap-dependent translation by treatment with agents [4EASO, 4EGI-1] that suppress host cell translation or by forcing cells to produce an activated repressor protein diminishes the strength of oncolytic viral efficacy.Malignant mesothelioma has a poor prognosis for which there remains an urgent need for successful treatment approaches. Infection with the Edmonston vaccine strain (MV-Edm) derivative of measles virus results in lysis of cancer cells and has been tested in clinical trials for numerous tumor types including mesothelioma. Many factors play a role in MV-Edm tumor cell selectivity and cytopathic activity while also sparing non-cancerous cells. The MV-Edm receptor CD46 (cluster of differentiation 46) was demonstrated to be significantly higher in mesothelioma cells than in control cells. In contrast, mesothelioma cells are not reliant upon the alternative MV-Edm receptor nectin-4 for entry. MV-Edm treatment of mesothelioma reduced cell viability and also invoked apoptotic cell death. Forced expression of eIF4E or translation stimulation following IGF-I (insulin-like growth factor 1) exposure strengthened the potency of measles virus oncolytic activity. It was also shown that repression of cap-dependent translation by treatment with agents [4EASO, 4EGI-1] that suppress host cell translation or by forcing cells to produce an activated repressor protein diminishes the strength of oncolytic viral efficacy.

4EGI-1 represses cap-dependent translation and regulates genome-wide translation in malignant pleural mesothelioma

SummaryDeregulation of cap-dependent translation has been implicated in the malignant transformation of numerous human tissues. 4EGI-1, a novel small-molecule inhibitor of cap-dependent translation, disrupts formation of the eukaryotic initiation factor 4F (eIF4F) complex. The effects of 4EGI-1-mediated inhibition of translation initiation in malignant pleural mesothelioma (MPM) were examined. 4EGI-1 preferentially inhibited cell viability and induced apoptosis in MPM cells compared to normal mesothelial (LP9) cells. This effect was associated with hypophosphorylation of 4E–binding protein 1 (4E–BP1) and decreased protein levels of the cancer-related genes, c-myc and osteopontin. 4EGI-1 showed enhanced cytotoxicity in combination with pemetrexed or gemcitabine. Translatome-wide polysome microarray analysis revealed a large cohort of genes that were translationally regulated upon treatment with 4EGI-1. The 4EGI-1-regulated translatome was negatively correlated to a previously published translatome regulated by eIF4E overexpression in human mammary epithelial cells, which is in agreement with the notion that 4EGI-1 inhibits the eIF4F complex. These data indicate that inhibition of the eIF4F complex by 4EGI-1 or similar translation inhibitors could be a strategy for treating mesothelioma. Genome wide translational profiling identified a large cohort of promising target genes that should be further evaluated for their potential significance in the treatment of MPM.

Oncolytic edmonston-strain measles virus as a novel therapeutic agent for non-small cell lung cancer.

e13536 Background: Oncolytic viruses are emerging as a novel therapy for many tumors. Attenuated measles virus (MV) is particularly promising due to its broad antitumor efficacy and track record of safe use in humans as a vaccine. Non-small cell lung cancers (NSCLC) overexpress the measles receptor, CD46, and therefore, we hypothesized that MV could be an effective therapy for NSCLC. Methods: H2009, H520, H522, H2030, A549, and H460 NSCLC cell lines and immortalized human bronchial epithelial cells (HBEC) were used for all experiments. Measles virus expressing GFP (MV-GFP) was used for all experiments. Proliferation assays were done by treating cells with MV-GFP or control at the desired multiplicity of infection (MOI) with and without 25nM gemcitabine for 72 hours. Cell number was assessed by counting viable cells using Trypan Blue exclusion method. Cells were assayed for the induction of apoptosis using poly(ADP) ribose polymerase (PARP) cleavage assay and Annexin V staining using the Guava-Nexin Assay....