Focal adhesion kinase a potential therapeutic target for pancreatic cancer and malignant pleural mesothelioma

The non-receptor cytoplasmic tyrosine kinase, Focal Adhesion Kinase (FAK) is known to play a key role in a variety of normal and cancer cellular functions such as survival, proliferation, migration and invasion. It is highly active and overexpressed in various cancers including Pancreatic Ductal Adenocarcinoma (PDAC) and Malignant Pleural Mesothelioma (MPM). Here, initially, we demonstrate that FAK is overexpressed in both PDAC and MPM cell lines. Then we analyze effects of two small molecule inhibitors PF-573228, and PF-431396, which are dual specificity inhibitors of FAK and proline rich tyrosine kinase 2 (PYK2), as well as VS-6063, another small molecule inhibitor that specifically inhibits FAK but not PYK2 for cell growth, motility and invasion of PDAC and MPM cell lines. Treatment with PF-573228, PF-431396 and VS-6063 cells resulted in a dose-dependent inhibition of growth and anchorage-independent colony formation in both cancer cell lines. Furthermore, these compounds suppressed the phosphorylation of FAK at its active site, Y397, and functionally induced significant apoptosis and cell cycle arrest in both cell lines. Using the ECIS (Electric cell-substrate impedance sensing) system, we found that treatment of both PF compounds suppressed adherence and migration of PDAC cells on fibronectin. Interestingly, 3D-tumor organoids derived from autochthonous KC (Kras;PdxCre) mice treated with PF-573228 revealed a significant decrease in tumor organoid size and increase in organoid cell death. Taken together, our results show that FAK is an important target for mesothelioma and pancreatic cancer therapy that merit further translational studies.

Genomic Heterogeneity as a Barrier to Precision Medicine in Gastroesophageal Adenocarcinoma

Gastroesophageal adenocarcinoma (GEA) is a lethal disease where targeted therapies, even when guided by genomic biomarkers, have had limited efficacy. A potential reason for the failure of such therapies is that genomic profiling results could commonly differ between the primary and metastatic tumors. To evaluate genomic heterogeneity, we sequenced paired primary GEA and synchronous metastatic lesions across multiple cohorts, finding extensive differences in genomic alterations, including discrepancies in potentially clinically relevant alterations. Multiregion sequencing showed significant discrepancy within the primary tumor (PT) and between the PT and disseminated disease, with oncogene amplification profiles commonly discordant. In addition, a pilot analysis of cell-free DNA (cfDNA) sequencing demonstrated the feasibility of detecting genomic amplifications not detected in PT sampling. Lastly, we profiled paired primary tumors, metastatic tumors, and cfDNA from patients enrolled in the personalized antibodies for GEA (PANGEA) trial of targeted therapies in GEA and found that genomic biomarkers were recurrently discrepant between the PT and untreated metastases. Divergent primary and metastatic tissue profiling led to treatment reassignment in 32% (9/28) of patients. In discordant primary and metastatic lesions, we found 87.5% concordance for targetable alterations in metastatic tissue and cfDNA, suggesting the potential for cfDNA profiling to enhance selection of therapy.Significance: We demonstrate frequent baseline heterogeneity in targetable genomic alterations in GEA, indicating that current tissue sampling practices for biomarker testing do not effectively guide precision medicine in this disease and that routine profiling of metastatic lesions and/or cfDNA should be systematically evaluated. Cancer Discov; 8(1); 37-48. ©2017 AACR.See related commentary by Sundar and Tan, p. 14See related article by Janjigian et al., p. 49This article is highlighted in the In This Issue feature, p. 1.

Met gene amplification and protein hyperactivation is a mechanism of resistance to both first and third generation EGFR inhibitors in lung cancer treatment

The 3rd generation epidermal growth factor receptor-tyrosine kinase inhibitors (EGFR-TKIs; e.g., AZD9291), which selectively and irreversibly inhibit EGFR activating and T790M mutants, represent very promising therapeutic options for patients with non-small cell lung cancer (NSCLC) that has become resistant to 1st generation EGFR-TKIs due to T790M mutation. However, eventual resistance to the 3rd generation EGFR-TKIs has already been described in the clinic, resulting in disease progression. Therefore, there is a great challenge and urgent need to understand how this resistance occurs and to develop effective strategies to delay or overcome the resistance. The current study has demonstrated that Met amplification and hyperactivation is a resistance mechanism to both 1st and 3rd generation EGFR-TKIs since both erlotinib- and AZD9291-resistant HCC827 cell lines possessed amplified Met gene and hyperactivated Met, and were cross-resistant to AZD9291 or erlotinib. Met inhibition overcame the resistance of these cell lines to AZD9291 both in vitro and in vivo, including enhancement of apoptosis or G1 cell cycle arrest. Hence, we suggest that Met inhibition is also an effective strategy to overcome resistance of certain EGFR-mutated NSCLCs with Met amplification to AZD9291, warranting the further clinical validation of our findings.

Abstract 2105: c-Met hyperactivation is an universal resistance mechanism to both first and third generation EGFR inhibitors

c-Met amplification and acquisition of a second T790M mutation are key mechanisms accounting for majority of resistant cases to first generation EGFR-tyrosine kinase inhibitors (EGFR-TKIs; i.e., erlotinib). The third generation EGFR-TKIs (e.g., AZD9291), which selectively and irreversibly inhibit EGFR activating and T790M mutants while sparing wild-type EGFR, represent very promising therapeutic options for NSCLC patients who have become resistant to 1st generation EGFR-TKIs due to T790M mutation. However, eventual resistance to the 3rd generation EGFR-TKIs has already been described in the clinic, resulting in disease progression. Therefore, there is a great challenge and urgent need to understand how this resistance occurs and to develop effective strategies to delay or overcome the resistance. We show that c-Met amplification and hyperactivation is an universal mechanism to both 1st and 3rd generation EGFR-TKIs since both erlotinib- and AZD9291-resistant HCC827 cell lines possessed elevated levels of c-Met (due to gene amplification) and p-c-Met and were cross-resistant to AZD9291 or erlotinib. Both chemical and genetic inhibition of c-Met overcame the resistance of these cell lines to AZD9291 including enhancement of apoptosis or G1 cell cycle arrest. Consistently the combination of AZD9291 and c-Met inhibition effectively inhibited the growth of both erlotinib- and AZD9291-resistant HCC827 xenografts in nude mice. Hence, we suggest that inhibition of c-Met is also an effective strategy to overcome resistance of EGFR-mutated NSCLCs with c-Met amplification or hyperactivation to AZD9291, providing the rationale for clinical development of this novel combination strategy. (SSR, TKO and SYS are Georgia Research Alliance Distinguished Cancer Scientists)

Citation Format: Puyu Shi, You-Take Oh, Guojing Zhang, Weilong Yao, Ping Yue, Rajani Kanteti, Jacob Riehm, Ravi Salgia, Taofeek Owonikoko, Suresh S. Ramalingam, Mingwei Chen, Shi-Yong Sun. c-Met hyperactivation is an universal resistance mechanism to both first and third generation EGFR inhibitors. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 2105.

C. elegans and mutants with chronic nicotine exposure as a novel model of cancer phenotype

We previously investigated MET and its oncogenic mutants relevant to lung cancer in C. elegans. The inactive orthlogues of the receptor tyrosine kinase Eph and MET, namely vab-1 and RB2088 respectively, the temperature sensitive constitutively active form of KRAS, SD551 (let-60; GA89) and the inactive c-CBL equivalent mutants in sli-1 (PS2728, PS1258, and MT13032) when subjected to chronic exposure of nicotine resulted in a significant loss in egg-laying capacity and fertility. While the vab-1 mutant revealed increased circular motion in response to nicotine, the other mutant strains failed to show any effect. Overall locomotion speed increased with increasing nicotine concentration in all tested mutant strains except in the vab-1 mutants. Moreover, chronic nicotine exposure, in general, upregulated kinases and phosphatases. Taken together, these studies provide evidence in support of C. elegans as initial in vivo model to study nicotine and its effects on oncogenic mutations identified in humans.

Whole-animal mounts of Caenorhabditis elegans for 3D imaging using atomic force microscopy

The 3D surface of Caenorhabditis elegans was imaged at nanometer resolution using atomic force microscopy (AFM). Oscillation of a medium stiffness silicon AFM cantilever at the upper second amplitude peak, typically 6 times above the fundamental frequency, vastly improved image quality on the moist, sticky, and soft worms. Whole-animal mounts of normal and double-headed mutants of the nematode worm were prepared and scanned. Well-preserved anatomical features including annuli, furrows, alae, and rows of never before seen nanometer-sized pores dotting the molted worm's outermost surface coat were resolved. Well-preserved anatomical features including annuli, furrows, alae, and rows of nanometer-sized pores or struts dotting the molted worm's outermost surface were resolved. This AFM method represents a simple and rapid new approach for nanometer-resolved 3D imaging and analysis of whole-animal specimens of C. elegans.

FROM THE CLINICAL EDITOR

In this interesting article the authors describe a new AFM sampling method to allow better images on whole-animal mounts such as C. elegans. This method would generate more information and in the future may be useful for differentiating even individual animals with different genetic backgrounds.

MET and PI3K/mTOR as a potential combinatorial therapeutic target in malignant pleural mesothelioma

Malignant pleural mesothelioma (MPM) is an aggressive disease with a poor prognosis. Studies have shown that both MET and its key downstream intracellular signaling partners, PI3K and mTOR, are overexpressed in MPM. Here we determined the combinatorial therapeutic efficacy of a new generation small molecule inhibitor of MET, ARQ 197, and dual PI3K/mTOR inhibitors NVP-BEZ235 and GDC-0980 in mesothelioma cell and mouse xenograft models. Cell viability results show that mesothelioma cell lines were sensitive to ARQ 197, NVP-BEZ235 and GDC-0980 inhibitors. The combined use of ARQ 197 with either NVP-BEZ235 or GDC-0980, was synergistic (CI<1). Significant delay in wound healing was observed with ARQ 197 (p<0.001) with no added advantage of combining it with either NVP-BEZ235 or GDC-0980. ARQ 197 alone mainly induced apoptosis (20±2.36%) that was preceded by suppression of MAPK activity, while all the three suppressed cell cycle progression. Both GDC-0980 and NVP-BEZ235 strongly inhibited activities of PI3K and mTOR as evidenced from the phosphorylation status of AKT and S6 kinase. The above observation was further substantiated by the finding that a majority of the MPM archival samples tested revealed highly active AKT. While the single use of ARQ 197 and GDC-0980 inhibited significantly the growth of MPM xenografts (p<0.05, p<0.001 respectively) in mice, the combination of the above two drugs was highly synergistic (p<0.001). Our results suggest that the combined use of ARQ 197/NVP-BEZ235 and ARQ 197/GDC-0980 is far more effective than the use of the drugs singly in suppressing MPM tumor growth and motility and therefore merit further translational studies.

Role of PAX8 in the regulation of MET and RON receptor tyrosine kinases in non-small cell lung cancer

BACKGROUND

Non-small cell lung cancers (NSCLC) are highly heterogeneous at the molecular level and comprise 75% of all lung tumors. We have previously shown that the receptor tyrosine kinase (RTK) MET frequently suffers gain-of-function mutations that significantly promote lung tumorigenesis. Subsequent studies from our lab also revealed that PAX5 transcription factor is preferentially expressed in small cell lung cancer (SCLC) and promotes MET transcription. PAX8, however, is also expressed in NSCLC cell lines. We therefore investigated the role of PAX8 in NSCLC.

METHODS

Using IHC analysis, PAX8 protein expression was determined in archival NSCLC tumor tissues (n = 254). In order to study the effects of PAX8 knockdown on NSCLC cellular functions such as apoptosis and motility, siRNA against PAX8 was used. Confocal fluorescence microscopy was used to monitor the localization of MET, RON and PAX8. The combinatorial effect of PAX8 knockdown and MET inhibition using SU11274 was investigated in NSCLC cell viability assay.

RESULTS

Relative levels of PAX8 protein were elevated (≥ + 2 on a scale of 0-3) in adenocarcinoma (58/94), large cell carcinoma (50/85), squamous cell carcinoma (28/47), and metastatic NSCLC (17/28; lymph node). Utilizing early progenitors isolated from NSCLC cell lines and fresh tumor tissues, we observed robust overexpression of PAX8, MET, and RON. PAX8 knockdown A549 cells revealed abrogated PAX8 expression with a concomitant loss in MET and the related RON kinase expression. A dramatic colocalization between the active form of MET (also RON) and PAX8 upon challenging A549 cells with HGF was visualized. A similar colocalization of MET and EGL5 (PAX8 ortholog) proteins was found in embryos of C. elegans. Most importantly, knockdown of PAX8 in A549 cells resulted in enhanced apoptosis (~6 fold) and decreased cell motility (~45%), thereby making PAX8 a potential therapeutic target. However, the combinatorial approach of PAX8 knockdown and treatment with MET inhibitor, SU11274, had marginal additive effect on loss of NSCLC cell viability.

CONCLUSION

PAX8 provides signals for growth and motility of NSCLC cells and is necessary for MET and RON expression. Further investigations are necessary to investigate the therapeutic potential of PA8 in NSCLC.

Combined MET inhibition and topoisomerase I inhibition block cell growth of small cell lung cancer

Small cell lung cancer (SCLC) is a devastating disease, and current therapies have not greatly improved the 5-year survival rates. Topoisomerase (Top) inhibition is a treatment modality for SCLC; however, the response is short lived. Consequently, our research has focused on improving SCLC therapeutics through the identification of novel targets. Previously, we identified MNNG HOS transforming gene (MET) to be overexpressed and functional in SCLC. Herein, we investigated the therapeutic potential of combinatorial targeting of MET using SU11274 and Top1 using 7-ethyl-10-hydroxycamptothecin (SN-38). MET and TOP1 gene copy numbers and protein expression were determined in 29 patients with limited (n = 11) and extensive (n = 18) disease. MET gene copy number was significantly increased (>6 copies) in extensive disease compared with limited disease (P = 0.015). Similar TOP1 gene copy numbers were detected in limited and extensive disease. Immunohistochemical staining revealed a significantly higher Top1 nuclear expression in extensive (0.93) versus limited (0.15) disease (P = 0.04). Interestingly, a significant positive correlation was detected between MET gene copy number and Top1 nuclear expression (r = 0.5). In vitro stimulation of H82 cells revealed hepatocyte growth factor (HGF)-induced nuclear colocalization of p-MET and Top1. Furthermore, activation of the HGF/MET axis enhanced Top1 activity, which was abrogated by SU11274. Combination of SN-38 with SU11274 dramatically decreased SCLC growth as compared with either drug alone. Collectively, these findings suggest that the combinatorial inhibition of MET and Top1 is a potentially efficacious treatment strategy for SCLC.

O-6-methylguanine-deoxyribonucleic acid methyltransferase methylation enhances response to temozolomide treatment in esophageal cancer

Background:

World-wide, esophageal cancer is a growing epidemic and patients frequently present with advanced disease that is surgically inoperable. Hence, chemotherapy is the predominate treatment. Cytotoxic platinum compounds are mostly used, but their efficacy is only moderate. Newer alkylating agents have shown promise in other tumor types, but little is known about their utility in esophageal cancer.

Methods:

We utilized archived human esophageal cancer samples and esophageal cancer cell lines to evaluate O-6-methylguanine-deoxyribonucleic acid methyltransferase (MGMT) hypermethylation status and determined sensitivity to the alkylating drug temozolomide (TMZ). Immunoblot analysis was performed to determine MGMT protein expression in cell lines. To assess and confirm the effect of TMZ treatment in a methylated esophageal cancer cell line in vivo, a mouse flank xenograft tumor model was utilized.

Results:

Nearly 71% (12/17) of adenocarcinoma and 38% (3/8) of squamous cell carcinoma (SCC) patient samples were MGMT hypermethylated. Out of four adenocarcinoma and nine SCC cell lines tested, one of each histology was hypermethylated. Immunoblot analyses confirmed that hypermethylated cell lines did not express the MGMT protein. In vitro cell viability assays showed the methylated Kyse-140 and FLO cells to be sensitive to TMZ at an IC₅₀ of 52-420 μM, whereas unmethylated cells Kyse-410 and SKGT-4 did not respond. In an in vivo xenograft tumor model with Kyse-140 cells, which are MGMT hypermethylated, TMZ treatment abrogated tumor growth by more than 60%.

Conclusion:

MGMT methylation may be an important biomarker in subsets of esophageal cancers and targeting by TMZ may be utilized to successfully treat these patients.

The EphB4 receptor tyrosine kinase promotes lung cancer growth: a potential novel therapeutic target

Despite progress in locoregional and systemic therapies, patient survival from lung cancer remains a challenge. Receptor tyrosine kinases are frequently implicated in lung cancer pathogenesis, and some tyrosine kinase inhibition strategies have been effective clinically. The EphB4 receptor tyrosine kinase has recently emerged as a potential target in several other cancers. We sought to systematically study the role of EphB4 in lung cancer. Here, we demonstrate that EphB4 is overexpressed 3-fold in lung tumors compared to paired normal tissues and frequently exhibits gene copy number increases in lung cancer. We also show that overexpression of EphB4 promotes cellular proliferation, colony formation, and motility, while EphB4 inhibition reduces cellular viability in vitro, halts the growth of established tumors in mouse xenograft models when used as a single-target strategy, and causes near-complete regression of established tumors when used in combination with paclitaxel. Taken together, these data suggest an important role for EphB4 as a potential novel therapeutic target in lung cancer. Clinical trials investigating the efficacy of anti-EphB4 therapies as well as combination therapy involving EphB4 inhibition may be warranted.

Critical role for the receptor tyrosine kinase EPHB4 in esophageal cancers

Esophageal cancer incidence is increasing and has few treatment options. In studying receptor tyrosine kinases associated with esophageal cancers, we have identified EPHB4 to be robustly overexpressed in cell lines and primary tumor tissues. In total, 94 squamous cell carcinoma, 82 adenocarcinoma, 25 dysplasia, 13 Barrett esophagus, and 25 adjacent or unrelated normal esophageal tissues were evaluated by immunohistochemistry. EPHB4 expression was significantly higher in all the different histologic categories than in adjacent normal tissues. In 13 esophageal cancer cell lines, 3 of the 9 SCC cell lines and 2 of the 4 adenocarcinomas expressed very high levels of EPHB4. An increased gene copy number ranging from 4 to 20 copies was identified in a subset of the overexpressing patient samples and cell lines. We have developed a novel 4-nitroquinoline 1-oxide (4-NQO)-induced mouse model of esophageal cancer that recapitulates the EPHB4 expression in humans. A specific small-molecule inhibitor of EPHB4 decreased cell viability in a time- and dose-dependent manner in 3 of the 4 cell lines tested. The small-molecule inhibitor and an EPHB4 siRNA also decreased cell migration (12%-40% closure in treated vs. 60%-80% in untreated), with decreased phosphorylation of various tyrosyl-containing proteins, EphB4, and its downstream target p125FAK. Finally, in a xenograft tumor model, an EPHB4 inhibitor abrogated tumor growth by approximately 60% compared with untreated control. EphB4 is robustly expressed and potentially serves as a novel biomarker for targeted therapy in esophageal cancers.

Sphingosine kinase 1 is required for mesothelioma cell proliferation: role of histone acetylation

Background

Malignant pleural mesothelioma (MPM) is a devastating disease with an overall poor prognosis. Despite the recent advances in targeted molecular therapies, there is a clear and urgent need for the identification of novel mesothelioma targets for the development of highly efficacious therapeutics.

Methodology/Principal Findings

In this study, we report that the expression of Sphingosine Kinase 1 (SphK1) protein was preferentially elevated in MPM tumor tissues (49 epithelioid and 13 sarcomatoid) compared to normal tissue (n = 13). In addition, we also observed significantly elevated levels of SphK1 and SphK2 mRNA and SphK1 protein expression in MPM cell lines such as H2691, H513 and H2461 compared to the non-malignant mesothelial Met5 cells. The underlying mechanism appears to be mediated by SphK1 induced upregulation of select gene transcription programs such as that of CBP/p300 and PCAF, two histone acetyl transferases (HAT), and the down regulation of cell cycle dependent kinase inhibitor genes such as p27Kip1 and p21Cip1. In addition, using immunoprecipitates of anti-acetylated histone antibody from SphK inhibitor, SphK-I2 treated Met5A and H2691 cell lysates, we also showed activation of other cell proliferation related genes, such as Top2A (DNA replication), AKB (chromosome remodeling and mitotic spindle formation), and suppression of p21 CIP1 and p27KIP1. The CDK2, HAT1 and MYST2 were, however, unaffected in the above study. Using SphK inhibitor and specific siRNA targeting either SphK1 or SphK2, we also unequivocally established that SphK1, but not SphK2, promotes H2691 mesothelioma cell proliferation. Using a multi-walled carbon nanotubes induced peritoneal mesothelioma mouse model, we showed that the SphK1−/− null mice exhibited significantly less inflammation and granulamatous nodules compared to their wild type counterparts.

Conclusions/Significance

The lipid kinase SphK1 plays a positive and essential role in the growth and development of malignant mesothelioma and is therefore a likely therapeutic target.

The database of chromosome imbalance regions and genes resided in lung cancer from Asian and Caucasian identified by array-comparative genomic hybridization

BACKGROUND

Cancer-related genes show racial differences. Therefore, identification and characterization of DNA copy number alteration regions in different racial groups helps to dissect the mechanism of tumorigenesis.

METHODS

Array-comparative genomic hybridization (array-CGH) was analyzed for DNA copy number profile in 40 Asian and 20 Caucasian lung cancer patients. Three methods including MetaCore analysis for disease and pathway correlations, concordance analysis between array-CGH database and the expression array database, and literature search for copy number variation genes were performed to select novel lung cancer candidate genes. Four candidate oncogenes were validated for DNA copy number and mRNA and protein expression by quantitative polymerase chain reaction (qPCR), chromogenic in situ hybridization (CISH), reverse transcriptase-qPCR (RT-qPCR), and immunohistochemistry (IHC) in more patients.

RESULTS

We identified 20 chromosomal imbalance regions harboring 459 genes for Caucasian and 17 regions containing 476 genes for Asian lung cancer patients. Seven common chromosomal imbalance regions harboring 117 genes, included gain on 3p13-14, 6p22.1, 9q21.13, 13q14.1, and 17p13.3; and loss on 3p22.2-22.3 and 13q13.3 were found both in Asian and Caucasian patients. Gene validation for four genes including ARHGAP19 (10q24.1) functioning in Rho activity control, FRAT2 (10q24.1) involved in Wnt signaling, PAFAH1B1 (17p13.3) functioning in motility control, and ZNF322A (6p22.1) involved in MAPK signaling was performed using qPCR and RT-qPCR. Mean gene dosage and mRNA expression level of the four candidate genes in tumor tissues were significantly higher than the corresponding normal tissues (P<0.001~P=0.06). In addition, CISH analysis of patients indicated that copy number amplification indeed occurred for ARHGAP19 and ZNF322A genes in lung cancer patients. IHC analysis of paraffin blocks from Asian Caucasian patients demonstrated that the frequency of PAFAH1B1 protein overexpression was 68% in Asian and 70% in Caucasian.

CONCLUSIONS

Our study provides an invaluable database revealing common and differential imbalance regions at specific chromosomes among Asian and Caucasian lung cancer patients. Four validation methods confirmed our database, which would help in further studies on the mechanism of lung tumorigenesis.

Differential expression of RON in small and non-small cell lung cancers

RON is a MET related receptor tyrosine kinase (RTK) and its natural ligand is macrophage stimulating protein (MSP). RON plays a very important role in the regulation of inflammation. Several studies have previously reported overexpression of RON in a variety of cancers including lung and identified numerous RON alternate splice forms that very likely contribute to tumor growth and metastasis. Here, we have analyzed the expression of total RON protein as well as its kinase-active form (phospho-RON) in 175 archival lung tumor FFPE (formalin fixed paraffin embedded) samples that included non-small-cell lung cancer (NSCLC) and small cell lung cancer (SCLC), and their metastatic forms. The frequency and intensity of RON protein expression was much higher in lung tumors of neuroendocrine origin such as SCLC and in secondary tumors that metastasized to brain. In addition, the majority of the expressed RON protein was phospho-RON. We also identified 62, and 30 kDa isoforms of RON (GenBank accession numbers are JN689381 and JN689382) using RNA isolated from pooled lung cancer cell lines and RT-PCR. A majority of the NSCLC cell lines expressed a 150 kDa band that corresponded to the RON β chain and 120 kDa band in the panel of SCLC cell lines tested. RON was expressed on the cell surface in NSCLC cell lines. Finally, knock down of RON expression resulted in a significant loss in viability as well as motility in lung cancer cells suggesting that RON is a potential therapeutic target.

Abstract 1861: EPHB4 as a potential therapeutic target for esophageal cancer

Despite substantial improvements in screening, diagnosis, and treatment of esophageal cancer, the prognosis of this disease remains bleak. Survival at 5 years for all esophageal cancer patients taken together, with amenable treatments and with or without surgery ranges from 5-20% (Cancer Facts and Figures. American Cancer Society 2011). Although a multidisciplinary approach to include surgery, radiation, and chemotherapy, alone or in combination, attempts to improve the survival of this aggressive disease, these statistics underscore the continued need for attention to this disease and for identification of new targets in its treatment. We have been studying the role of receptor tyrosine kinases (RTKs) in cancer, particularly the EphB4 receptor, which has become increasingly associated with the pathobiology of adult cancers over the past several years. It has been shown to be aberrantly expressed and/or to play an oncogenic role in cancers of the breast, bladder, ovary, uterus, colon, head and neck, and prostate through its effects on cellular motility, growth, and migration, as well as on tumors’ ability to induce neoangiogenesis. To date, its role and potential as a target for therapy in different cancers have not been thoroughly investigated and remain poorly understood. Targeted inactivation of EphB4 and its ligand Ephrin-B2 have demonstrated that both are essential for angiogenic remodeling and embryonic survival (Adams and Klein 2000; Kim, Hu et al. 2008). In this report, we determine that EphB4 is overexpressed, has increased gene copy number and is involved in enhanced motility and migration in esophageal cancer. Archival patient samples consisting of 93 squamous cell carcinoma, 100 adenocarcinoma and 25 adjacent normal control samples as well as four adenocarcinoma and nine squamous cell carcinoma cell lines were used for the studies. Extensive mouse modeling of esophageal cancer was also used. We have reported that there is consistently higher expression of EphB4 in both squamous and adenocarcinoma compared to adjacent normal tissue with a statistically significant correlation between EphB4 expression and higher grades of squamous cell carcinoma. In a chemically induced esophageal squamous cell carcinoma model in mice, EphB4 was found overexpressed compared to normal controls. This study identifies EphB4 to be an important pathway in esophageal neoplastic lesions. It would now be useful to bring this to clinical fruition.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 1861. doi:1538-7445.AM2012-1861

Abstract A37: Interim analysis of CALGB 150607: A pilot study of the mutational & expression status of MET, HGF, EGFR, KRAS, p53, c-CBL, and E-cadherin in resected lung adenocarcinoma specimens

MET is a receptor tyrosine kinase that plays a critical role in proliferation, angiogenesis, invasion, and metastasis. It has been shown to be dysregulated in a number of malignancies, including non-small cell lung cancer (NSCLC). Despite reports of alterations in MET, and its ligand, HGF, being highly associated with advanced pathological stage and worse outcome in patients with NSCLC, the value of MET as a prognostic biomarker remains unclear. The primary objective of this study is to determine the correlation between MET alterations and expression with stage and overall survival in adenocarcinoma (AC) patients in a large cohort of patients. The secondary objectives are to determine the correlation between overall survival and the following: 1) epithelial mesenchymal transition (EMT), 2) EGFR mutations & expression, 3) KRAS mutations, 4) TP53 mutations, and 5) CBL mutations. In addition, sera levels of circulating MET and HGF will be evaluated in order to determine their potential as prognostic factors. MET, EGFR exons 18–21, TP53 exons 4–10, KRAS exon 2, and CBL exons 2–16 were sequenced using standard PCR and sequencing techniques. Standard immunohistochemistry (IHC) techniques were used to evaluate MET, phosphorylated (pMET Y1003 and Y1230/34/35) p53, HGF, EGFR, and E-cadherin expression. A total of 280 patients will be included in this study, and the interim analysis reported herein evaluated 100 patients. The intensity of cytoplasmic or membranous staining was scored on fourpoint scale: (0, no staining; 1+, weak; 2+, moderate; 3+, strong staining). The extent of staining was scored on a similar scale (0, negative; 1+, 1–10%; 2+, 11–50%; 3+, &gt; 50%). The product of the intensity and extent of staining yielded final scores between 0 and 9. The mean expressions were: MET 3.6 (±0.3); pY1230/34/35 MET 2.0 (±0.2); pY1003MET 4.6 (±0.3); HGF 4.4 (±0.3); EGFR 4.3 (±0.3); TP53 3.7 (±0.3); and E-cadherin 5.5 (±0.3). In ten patient samples, six non-synonymous (NS) mutations were detected in MET (SEMA domain: E168D, M362T, N375S, and Q318K; JM domain: T992I and R970C). In EGFR, the NS mutation L858R was detected in two patients. We detected 12 NS mutations in TP53 (exon 4: E68*, P72R; exon 5: V157F, R175H, I162F, H193Y, Y163D; exon 8: R273L, R273C, V274L, A276F, and G266*). Four NS mutations were detected in exon 2 of KRAS (G12C, G12V, G12D, and G12S). Three mutations were found in the proline-rich region of CBL (L676P, A677S and A678S). ELISAs were utilized to determine soluble MET and HGF levels in pre- and postoperative sera samples. Soluble MET serum levels were significantly increased (p&lt;0.0005) in post-operative samples (1760 ng/ml ± 51.66) compared to pre-operative samples (1585 ng/ml ± 44.61). HGF levels were similar in pre-operative (1008 pg/ml ± 74.8) and post-operative samples (1266 pg/ml ± 175.9). In conclusion, MET and pMET (Y1003) were highly expressed in resected lung AC specimens. NS mutations were detected in all of the oncogenic genes assessed and the functional relevance of these mutations on tumorigenesis remains to be determined. Interestingly, novel MET mutations were detected in key functional domains; the SEMA domain which is critical for dimerization and ligand binding, and the JM domain which is important for MET downregulation via c-CBL. We will correlate these mutational and expression data with clinical outcomes in order to determine the prognostic role of MET.

Proteomic characterization of non-small cell lung cancer in a comprehensive translational thoracic oncology database

BACKGROUND

In recent years, there has been tremendous growth and interest in translational research, particularly in cancer biology. This area of study clearly establishes the connection between laboratory experimentation and practical human application. Though it is common for laboratory and clinical data regarding patient specimens to be maintained separately, the storage of such heterogeneous data in one database offers many benefits as it may facilitate more rapid accession of data and provide researchers access to greater numbers of tissue samples.

DESCRIPTION

The Thoracic Oncology Program Database Project was developed to serve as a repository for well-annotated cancer specimen, clinical, genomic, and proteomic data obtained from tumor tissue studies. The TOPDP is not merely a library-it is a dynamic tool that may be used for data mining and exploratory analysis. Using the example of non-small cell lung cancer cases within the database, this study will demonstrate how clinical data may be combined with proteomic analyses of patient tissue samples in determining the functional relevance of protein over and under expression in this disease. Clinical data for 1323 patients with non-small cell lung cancer has been captured to date. Proteomic studies have been performed on tissue samples from 105 of these patients. These tissues have been analyzed for the expression of 33 different protein biomarkers using tissue microarrays. The expression of 15 potential biomarkers was found to be significantly higher in tumor versus matched normal tissue. Proteins belonging to the receptor tyrosine kinase family were particularly likely to be over expressed in tumor tissues. There was no difference in protein expression across various histologies or stages of non-small cell lung cancer. Though not differentially expressed between tumor and non-tumor tissues, the over expression of the glucocorticoid receptor (GR) was associated improved overall survival. However, this finding is preliminary and warrants further investigation.

CONCLUSION

Though the database project is still under development, the application of such a database has the potential to enhance our understanding of cancer biology and will help researchers to identify targets to modify the course of thoracic malignancies.

RON (MST1R) is a novel prognostic marker and therapeutic target for gastroesophageal adenocarcinoma

RON (MST1R) is one of two members of the MET receptor tyrosine kinase family, along with parent receptor MET. RON has a putative role in several cancers, but its expression and function is poorly characterized in gastroesophageal adenocarcinoma. A recognized functional role of MET tyrosine kinase in gastroesophageal cancer has led to early phase clinical trials using MET inhibitors, with unimpressive results. Therefore, the role of RON in gastroesophageal cancer, as well as its role in cooperative signaling with MET and as a mechanism of resistance to MET inhibition, was studied in gastroesophageal tissues and cell lines. By IHC, RON was highly over-expressed in 74% of gastroesophageal samples (n=94), and over-expression was prognostic of poor survival (p=0.008); RON and MET co-expression occurred in 43% of samples and was prognostic of worst survival (p=0.03). High MST1R gene copy number by quantitative polymerase chain reaction, and confirmed by fluorescence in situ hybridization and/or array comparative genomic hybridization, was seen in 35.5% (16/45) of cases. High MST1R gene copy number correlated with poor survival (p=0.01), and was associated with high MET and ERBB2 gene copy number. A novel somatic MST1R juxtamembrane mutation R1018G was found in 11% of samples. RON signaling was functional in cell lines, activating downstream effector STAT3, and resulted in increased viability over controls. RON and MET co-stimulation assays led to enhanced malignant phenotypes over stimulation of either receptor alone. Growth inhibition as evidenced by viability and apoptosis assays was optimal using novel blocking monoclonal antibodies to both RON and MET, versus either alone. SU11274, a classic MET small molecule tyrosine kinase inhibitor, blocked signaling of both receptors, and proved synergistic when combined with STAT3 inhibition (combination index < 1). These preclinical studies define RON as an important novel prognostic marker and therapeutic target for gastroesophageal cancer warranting further investigation.

Abstract 1625: Role of EphB4 in esophageal cancer: Expression, amplification, and therapeutic inhibition

EphB4 is a member of the largest family of receptor tyrosine kinases (RTKs), classically associated with neural development and vascular patterning in embryonic life. The cellular responses to Eph receptor stimulation by their ephrin ligands are important in mediating a wide range of biological activities, including angiogenesis, cell segregation, cell attachment, shape, and motility. EphB4 has been showed to play an oncogenic role in a number of tumors, and we report the first investigation into its role in esophageal cancer, a disease whose survival has not improved and would benefit from the identification of new targets in its treatment. We have addressed this need by exploring the Eph/ephrin receptor tyrosine kinase pathway. We utilized tissues archived at the University of Chicago as well as commercially purchased TMAs to evaluate the expression of EphB4 by IHC. Approximately 93 squamous cell carcinoma, 100 adenocarcinoma and 25 adjacent normal control samples were utilized. In addition, four adenocarcinoma and nine squamous cell carcinma cell lines were used for in vitro studies. Statistical analysis of IHC data showed a consistently higher expression of EphB4 in both squamous and adenocarcinoma compared to adjacent normal tissue. A statistically significant correlation was established between EphB4 expression and higher grades of squamous cell carcinoma, suggesting that overexpression of EphB4 in squamous cell carcinoma is directly linked to clinically aggressive tumors. The EphB4 gene was found amplified in 8/16 squamous cell carcinoma (30% with a gene copy number ≥ 3, 30% with &gt;8 copies and 10% with a copy number of 20. Of the adenocarcinomas, 3/7 samples were amplified (43% with a gene copy number of ≥4, and 14% &gt;8 copies). Three of 9 squamous cell carcinoma cell lines had a gene copy number ≥4 and rest of them had no significant variation. Only one of four adenocarcinoma cell lines had an increased gene copy number. In vitro experiments with EphB4 specific siRNA inhibited the motility and proliferation of cultured cells and the inhibition of EphB4 specifically abrogated the phosphorylation of functional proteins associated with cell motility and proliferation, especially that of phospho-FAK and phospo-AKT, the expression of which were abrogated completely by the inhibition of EphB4. Our data imply that EphB4 plays a crucial role in esophageal cancer and should be further evaluated as a therapeutic target in this disease.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr 1625. doi:10.1158/1538-7445.AM2011-1625

Abstract 2341: Functional analysis of paxillin mutations identified in lung cancer and malignant mesothelioma: Implications for cell migration/motility

Paxillin is a 68 kDa focal adhesion protein that provides multiple docking sites at the plasma membrane for an array of signaling molecules and helps form a structural link between the extracellular matrix and the actin cytoskeleton. It is essential in actin filament assembly and focal adhesion formation. Focal adhesion complexes are the drivers of cell spreading and migration, adhesion to the extracellular matrix and matrix remodeling by fibrillar adhesions in which paxillin plays a major role. It has been shown that the modulation of tyrosine phosphorylation of paxillin regulates both the assembly and turnover of adhesion sites and phosphorylated paxillin enhances lamellipodial protrusions whereas non-phosphorylated paxillin is essential for fibrillar adhesion formation. We have previously reported that in lung cancer, paxillin was over expressed, amplified and mutated in a significant number of patient samples and the protein upregulated in higher stages of lung cancer compared with lower stages (Jagadeeswaran et al, 2008). We recently showed paxillin gene to be amplified in some pre-neoplastic lung lesions. Among the mutations we described, A127T enhanced cell proliferation, focal adhesion formation and colocalization with Bcl-2 in lung cancer cells. We have now analyzed 50 epithelioid, 16 sarcomatoid, and one mixed malignant pleural mesothelioma tissue, and compared to 40 normal adjacent lung parenchyma (pneumocytes and endothelial cells) by immunohistochemistry. Automated cellular imaging was used to calculate average staining intensity as an integrated optical density (IOD). Whereas normal lung had IODs of 45 for paxillin, epithelioid MPM had IODs of 268 and sarcomatoid 331. This demonstrates that paxillin is highly upregulated in both epithelioid as well as sarcomatoid. To further study the effects of activating mutations of paxillin, we cloned the most commonly occurring paxillin mutations in a GFP tagged vector and transiently transfect HEK-293 cells. Utilizing live-cell imaging to systematically study the effects of wild-type paxillin versus mutants, we created a mathematical model that recapitulates the salient features of the measured dynamics, and conclude that compared to wild-type, some mutant clones confer a) enhanced focal adhesion formation, b) increased filopodia and lamellipodia formation c) increased mobility and d) increased cell displacement in transiently transfected HEK-293 cells. We believe that paxillin is an important molecule in thoracic cancer including lung and malignant mesothelioma, and its therapeutic potential needs to be explored further.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr 2341. doi:10.1158/1538-7445.AM2011-2341

Role of protein kinase C β and vascular endothelial growth factor receptor in malignant pleural mesothelioma: Therapeutic implications and the usefulness of Caenorhabditis elegans model organism

PURPOSE

To examine the role of both protein kinase C (PKC)-β and vascular endothelial growth factor receptor (VEGFR)-2 in malignant pleural mesothelioma (MPM) using respective inhibitors, enzastaurin and KRN633.

MATERIALS AND METHODS

MPM cell lines, control cells, and a variety of archived MPM tumor samples were used to determine the protein expression levels of PKC-β, VEGFR-2, VEGF, and p-AKT. Effects of enzastaurin and KRN633 on phosphorylation status of key signaling molecules and viability of the mesothelioma cells were determined. The common soil nematode, Caenorhabditis elegans, was treated with enzastaurin to determine its suitability to screen for highly potent kinase inhibitors.

RESULTS

PKC-β1, PKC-β2 and VEGFR-2/KDR were overexpressed in MPM cell lines and MPM tumor tissues. Enzastaurin treatment resulted in significant loss in viability of VEGF induced cell proliferation; however, the effect of KRN633 was much less. Enzastaurin also dramatically decreased the phosphorylation of PKC-β, its downstream target p-AKT, and surprisingly, the upstream VEGFR-2. The combination of the two drugs at best was additive and similar results were obtained with respect to cell viability. Treatment of C. elegans with enzastaurin resulted in clear phenotypic changes and the worms were hypermotile with abnormal pattern and shape of eggs, suggesting altered fecundity.

CONCLUSIONS

PKC-β1 and VEGFR-2 are both excellent therapeutic targets in MPM. Enzastaurin was better at killing MPM cells than KRN633 and the combination lacked synergy. In addition, we show here that C. elegans can be used to screen for the next generation inhibitors as treatment with enzastaurin resulted in clear phenotypic changes that could be assayed.

Functional EGFR germline polymorphisms may confer risk for EGFR somatic mutations in non-small cell lung cancer, with a predominant effect on exon 19 microdeletions

Somatic mutations in the EGFR tyrosine kinase domain play a critical role in the development and treatment of non-small cell lung cancer (NSCLC). Strong genetic influence on susceptibility to these mutations has been suggested. To identify the genetic factors conferring risk for the EGFR tyrosine kinase mutations in NSCLC, a case-control study was conducted in 141 Taiwanese NSCLC patients by focusing on three functional polymorphisms in the EGFR gene [-216G/T, intron 1 (CA)n, and R497K]. Allelic imbalance of the EGFR -216G/T polymorphism was also tested in the heterozygous patients and in the NCI-60 cancer cell lines to further verify its function. We found that the frequencies of the alleles -216T and CA-19 are significantly higher in the patients with any mutation (P = 0.032 and 0.01, respectively), in particular in those with exon 19 microdeletions (P = 0.006 and 0.033, respectively), but not in the patients with L858R mutation. The -216T allele is favored to be amplified in both tumor DNA of lung cancer patients and cancer cell lines. We conclude that the local haplotype structures across the EGFR gene may favor the development of cellular malignancies and thus significantly confer risk to the occurrence of EGFR mutations in NSCLC, particularly the exon 19 microdeletions.

Generation of comprehensive thoracic oncology database--tool for translational research

The Thoracic Oncology Program Database Project was created to serve as a comprehensive, verified, and accessible repository for well-annotated cancer specimens and clinical data to be available to researchers within the Thoracic Oncology Research Program. This database also captures a large volume of genomic and proteomic data obtained from various tumor tissue studies. A team of clinical and basic science researchers, a biostatistician, and a bioinformatics expert was convened to design the database. Variables of interest were clearly defined and their descriptions were written within a standard operating manual to ensure consistency of data annotation. Using a protocol for prospective tissue banking and another protocol for retrospective banking, tumor and normal tissue samples from patients consented to these protocols were collected. Clinical information such as demographics, cancer characterization, and treatment plans for these patients were abstracted and entered into an Access database. Proteomic and genomic data have been included in the database and have been linked to clinical information for patients described within the database. The data from each table were linked using the relationships function in Microsoft Access to allow the database manager to connect clinical and laboratory information during a query. The queried data can then be exported for statistical analysis and hypothesis generation.

Crizotinib (PF02341066) as a ALK /MET inhibitor- Special Emphasis as a Therapeutic Drug Against Lung Cancer

There are a number of molecular abnormalities that can occur in normal cells to induce a malignant phenotype. Recently, the receptor tyrosine kinase anaplastic lymphoma kinase (ALK) has been shown to have gain-of-function when partnered with different proteins. As an example, on chromosome 2p, with inversion, there is translocation with generation of EML4-ALK tyrosine kinase in lung cancer. In a phase I trial, EML4-ALK patients were selected to determine the response to a potent small molecule tyrosine kinase inhibitor crizotinib (previously identified as PF02341066). Dramatic durable responses were observed with crizotinib at 250 mg twice a day (orally). Interestingly, crizotinib also has activity against MET receptor tyrosine kinase. We have previously shown that MET can be overexpressed, sometimes mutated, or sometimes amplified in lung cancer. Thus, this review will emphasize the characteristics of crizotinib, and detail the clinical experience.

EphA2 mutation in lung squamous cell carcinoma promotes increased cell survival, cell invasion, focal adhesions, and mammalian target of rapamycin activation

Non-small cell lung cancer (NSCLC) has a poor prognosis and improved therapies are needed. Expression of EphA2 is increased in NSCLC metastases. In this study, we investigated EphA2 mutations in NSCLC and examined molecular pathways involved in NSCLC. Tumor and cell line DNA was sequenced. One EphA2 mutation was modeled by expression in BEAS2B cells, and functional and biochemical studies were conducted. A G391R mutation was detected in H2170 and 2/28 squamous cell carcinoma patient samples. EphA2 G391R caused constitutive activation of EphA2 with increased phosphorylation of Src, cortactin, and p130(Cas). Wild-type (WT) and G391R cells had 20 and 40% increased invasiveness; this was attenuated with knockdown of Src, cortactin, or p130(Cas). WT and G391R cells demonstrated a 70% increase in focal adhesion area. Mammalian target of rapamycin (mTOR) phosphorylation was increased in G391R cells with increased survival (55%) compared with WT (30%) and had increased sensitivity to rapamycin. A recurrent EphA2 mutation is present in lung squamous cell carcinoma and increases tumor invasion and survival through activation of focal adhesions and actin cytoskeletal regulatory proteins as well as mTOR. Further study of EphA2 as a therapeutic target is warranted.

Abstract 2176: Vascular endothelial growth factor receptor-2 (VEGFR-2) gene variations in bronchioloalveolar cell carcinoma (BAC)

Background VEGF receptor-2 (VEGFR-2) is a key receptor in VEGF-mediated angiogenesis. It plays a significant role in tumor growth and development of metastases. A few studies suggested the angiogenic feature of bronchioalveolar cell carcinoma (BAC), a rare subtype of adenocarcinoma. However the biology of VEGFR-2 in BAC has not been clearly characterized, probably due to its rarity. We sought to determine whether differences in VEGFR-2 expression and microvessel density (MVD) in adenocarcinoma with BAC features (AWBF) might be due to heritable genetic variation in the VEGFR-2 gene. Differences in VEGFR-2 expression and MVD between the pure BAC component of tumor and AWBF, and their comparison with adjacent normal tissue, were also investigated.

Methods DNA was extracted from 46 formalin-fixed paraffin embedded AWBF tissues. Four single-nucleotide polymorphisms (SNPs) and four in/dels were genotyped in all tumors. Tissue microarrays (TMAs) were constructed with tumor tissue (pure BAC component and AWBF component for each tumor) and paired adjacent normal lung tissue. TMAs were stained with anti-VEGFR-2 and anti-phosphorylated-VEGFR-2 (pVEGFR-2) antibodies (scoring: 0-9). MVD was determined by staining with an antibody against CD105, and 95% of the samples had either diffused high or focal high staining.

Results The −271G&gt;A genotype showed a clear gene-dosage effect on pVEGFR-2 expression (GG&gt;GA&gt;AA, p=0.04, linear trend analysis) in AWBF but not in BAC (p&gt;0.1). The −271G&gt;A genotype does not affect the MVD in both BAC and AWBF (linear trend analysis and Kruskal-Wallis, p&gt;0.1). The other SNPs and in/dels did not show any significant association with VEGFR-2, pVEGFR-2, and MVD (p&gt;0.1). VEGFR-2 and pVEGFR-2 expression in tumor (AWBF and pure BAC) was more than 10 times higher the paired normal tissue (p&lt;0.001, Wilcoxon matched pairs test). A trend for higher VEGFR-2 expression in AWBF compared to pure BAC (mean score 4.2 vs. 3.8, p=0.08, Wilcoxon matched pairs test) was observed, while no difference was observed for pVEGFR-2 (p&gt;0.1). For MVD, although the proportion of diffused high staining was higher in BAC (60%) vs. AWBF (47%), this difference is not statistically significant (p&gt;0.1, Fisher's exact test).

Discussion Our study shows that heritable gene variation of −271G&gt;A in VEGFR-2 might reduce the expression of VEGFR-2 in AWBF. This is consistent with the effect of −271G&gt;A in a luciferase assay (Ye et al., AACR 2007), as well as its effect on VEGFR-2 and pVEGFR-2 staining in breast cancer (Cerri et al., SABCS 2009, abstract #904). Although our data are suggestive of different pattern of angiogenesis between pure BAC and AWBF, our sample size is too small to draw any definitive conclusions. Additional studies are ongoing to replicate these findings that will establish the role of genetic variation as a determinant of VEGFR-2 expression in BAC, and the biology of angiogenesis in this rare tumor.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr 2176.

CBL is frequently altered in lung cancers: its relationship to mutations in MET and EGFR tyrosine kinases

Background

Non-small cell lung cancer (NSCLC) is a heterogeneous group of disorders with a number of genetic and proteomic alterations. c-CBL is an E3 ubiquitin ligase and adaptor molecule important in normal homeostasis and cancer. We determined the genetic variations of c-CBL, relationship to receptor tyrosine kinases (EGFR and MET), and functionality in NSCLC.

Methods and Findings

Using archival formalin-fixed paraffin embedded (FFPE) extracted genomic DNA, we show that c-CBL mutations occur in somatic fashion for lung cancers. c-CBL mutations were not mutually exclusive of MET or EGFR mutations; however they were independent of p53 and KRAS mutations. In normal/tumor pairwise analysis, there was significant loss of heterozygosity (LOH) for the c-CBL locus (22%, n = 8/37) and none of these samples revealed any mutation in the remaining copy of c-CBL. The c-CBL LOH also positively correlated with EGFR and MET mutations observed in the same samples. Using select c-CBL somatic mutations such as S80N/H94Y, Q249E and W802* (obtained from Caucasian, Taiwanese and African-American samples, respectively) transfected in NSCLC cell lines, there was increased cell viability and cell motility.

Conclusions

Taking the overall mutation rate of c-CBL to be a combination as somatic missense mutation and LOH, it is clear that c-CBL is highly mutated in lung cancers and may play an essential role in lung tumorigenesis and metastasis.

MET, HGF, EGFR, and PXN gene copy number in lung cancer using DNA extracts from FFPE archival samples and prognostic significance

Gene copy number analysis for some of the important molecules in lung tumorogenesis, such as MET, hepatocyte growth factor [(HGF), ligand for MET), epidermal growth factor receptor (EGFR), and paxillin (PXN), is likely to determine both the type of treatment and prognosis. Formalin-fixed paraffin-embedded (FFPE) archival tumor tissue samples are an excellent source for determining key molecular changes in the OncoGenome; however, existing extraction procedures yield relatively poor quality genomic DNA fragments. Although FISH is the method of choice for determining amplification of a gene, a more rapid quantitative poly-merase chain reaction (qPCR) technique to determine gene copy number can be used when reasonably good quality genomic DNA is available. We report here a relatively rapid method based on microwave/chelex-100 treatment that gives rise to genomic DNA fragments ranging from 1 to 12 Kb and beyond, thereby attesting to its superior quality. Genomic PCR for beta-globin gene gave reliable and reproducible results. The number of steps for extracting the DNA was kept to a minimum, and instead of precipitating the DNA, we preserved the genomic DNA extracts so as to prevent a loss in DNA yield. We found the extracts to be stable and amenable to qPCR and mutational analysis. Using lung adenocarcinoma FFPE samples and cell lines derived from lung adenocarcinomas, we demonstrated that the gene copy number for MET in lung adenocarcinoma tissue samples was preferentially increased over EGFR, HGF, and PXN and that it positively correlated with a better prognosis. In contrast, the genomic DNA extracted from 25 NSCLC cell lines gave a relatively higher gene copy number for all four genes evaluated. Our results indicate that the microwave/chelex-100-based method yields good-quality genomic DNA extracts that can be used for complex DNA analysis, such as determination of gene copy number. In addition, our data demonstrated that the adenocarcinoma cell lines potentially evolved under ex vivo conditions, and therefore, in genetic studies it is imperative to use primary tumors for generalized conclusions about lung tumors.

Ethnic differences and functional analysis of MET mutations in lung cancer

PURPOSE

African Americans have higher incidence and poorer response to lung cancer treatment compared with Caucasians. However, the underlying molecular mechanisms for the significant ethnic difference are not known. The present study examines the ethnic differences in the type and frequency of MET proto-oncogene (MET) mutation in lung cancer and correlated them with other frequently mutated genes such as epidermal growth factor receptor (EGFR), KRAS2, and TP53.

EXPERIMENTAL DESIGN

Using tumor tissue genomic DNA from 141 Asian, 76 Caucasian, and 66 African American lung cancer patients, exons coding for MET and EGFR were PCR amplified, and mutations were detected by sequencing. Mutation carriers were further screened for KRAS2 and TP53 mutations. Functional implications of important MET mutations were explored by molecular modeling and hepatocyte growth factor binding studies.

RESULTS

Unlike the frequently encountered somatic mutations in EGFR, MET mutations in lung tumors were germline. MET-N375S, the most frequent mutation of MET, occurred in 13% of East Asians compared with none in African Americans. The frequency of MET mutations was highest among male smokers and squamous cell carcinoma. The MET-N375S mutation seems to confer resistance to MET inhibition based on hepatocyte growth factor ligand binding, molecular modeling, and apoptotic susceptibility to MET inhibitor studies.

CONCLUSIONS

MET in lung cancer tissues contained nonsynonymous mutations in the semaphorin and juxtamembrane domains but not in the tyrosine kinase domain. All the MET mutations were germline. East Asians, African-Americans, and Caucasians had different MET genotypes and haplotypes. MET mutations in the semaphorin domain affected ligand binding.

Enterohemorrhagic Escherichia coli suppresses inflammatory response to cytokines and its own toxin

Infection with the enteric pathogen enterohemorrhagic Escherichia coli (EHEC) causes a variety of symptoms ranging from nonbloody diarrhea to more severe sequelae including hemorrhagic colitis, altered sensorium and seizures, and even life-threatening complications, such as hemolytic uremic syndrome and thrombotic thrombocytopenic purpura. The more severe consequences of EHEC infection are attributable to the production of Shiga toxin (Stx) and its subsequent effects on the vasculature, which expresses high levels of the Stx receptor, Gb3. Interestingly, the intestinal epithelium does not express Gb3. Despite the lack of Gb3 receptor expression, intestinal epithelial cells translocate Stx. The effect of Stx on intestinal epithelial cells is controversial with some studies demonstrating induction of inflammation and others not. This may be difficult to resolve because EHEC expresses both proinflammatory molecules, such as flagellin, and factor(s) that dampen the inflammatory response of epithelial cells. The goal of our study was to define the effect of Stx on the inflammatory response of intestinal epithelial cells and to determine whether infection by EHEC modulates this response. Here we show that Stx is a potent inducer of the inflammatory response in intestinal epithelial cells and confirm that EHEC attenuates the induction of IL-8 by host-derived proinflammatory cytokines. More importantly, however, we show that infection with EHEC attenuates the inflammatory response by intestinal epithelial cells to its own toxin. We speculate that the ability of EHEC to dampen epithelial cell inflammatory responses to Stx and cytokines facilitates intestinal colonization.

Response and survival in African American (AA) patients (pts) with non-small cell lung cancer (NSCLC) treated with erlotinib (E)

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Background: Pts who respond to the EGFR- tyrosine kinase inhibitors (TKI's) frequently have activating mutations in the kinase domain of EGFR or EGFR overexpression. EGFR activating mutations correlate with adenocarcinoma histology, non-smoking history, female gender, and Asian ethnicity. The presence of EGFR kinase domain mutations is predictive of response but, the relationship is not always concordant. Furthermore, mutations may not predict survival benefit with TKI therapy and other factors are likely involved. It has also been determined that EGFR and met can crosstalk, and serve as potential mechanism of resistance in NSCLC. Most data collected to date on response and overall survival with EGFR-TKI's have been in the Caucasian or Asian community. Hence we collected data specific to the AA pt as they tend to have worse outcomes stage for stage. The purpose of this study is to report the response rate, overall survival, progression free survival (PFS) and clinical characteristics of AA pts with NSCLC treated with an EGFR-TKI. We will correlate these data with EGFR mutation and c-Met expression/mutations/amplifications for markers of NSCLC. Methods: We have listed patients with NSCLC receiving E therapy over the past 5 years. We then retrospectively collected demographic data (age, race, sex, and tobacco history), tumor histology, response rates, survival data and duration of response from AA pts treated with E as single agent. The response to E was correlated with outcome. Results: Data from 44 AA pts (27 women, 17 men) on erlotinib were reviewed. Mean age was 67.1 years (range 48–89 yrs), tobacco use (37 positive, 3 negative, and 4 not recorded). Histology included NSCLC not specified-14, squamous cell- 16, adenocarcinoma-11, large cell-1 and 2 not available. Overall response rate of 13.6% (6-PR, 16-SD, 18-progessive disease, and 4 patients lost to follow up). The PFS was 4.0 months; 95% CI: (2.5–6.6 mos) and overall survival 8.6 mos; 95% CI: (7.2–30.9 mos). EGFR mutations and c-Met analysis will be provided by ASCO meeting in May 2009. Conclusions: AA survival and response rates appear similar to previous data seen with all NSCLC patients receiving treatment with EGFR-TKI's. More data and relationship to biomarkers is needed in this population.

[Table: see text]

The MET receptor tyrosine kinase is a potential novel therapeutic target for head and neck squamous cell carcinoma

Recurrent/metastatic head and neck cancer remains a devastating disease with insufficient treatment options. We investigated the MET receptor tyrosine kinase as a novel target for the treatment of head and neck squamous cell carcinoma (HNSCC). MET/phosphorylated MET and HGF expression was analyzed in 121 tissues (HNSCC/normal) by immunohistochemistry, and in 20 HNSCC cell lines by immunoblotting. The effects of MET inhibition using small interfering RNA/two small-molecule inhibitors (SU11274/PF-2341066) on signaling, migration, viability, and angiogenesis were determined. The complete MET gene was sequenced in 66 head and neck cancer tissue samples and eight cell lines. MET gene copy number was determined in 14 cell lines and 23 tumor tissues. Drug combinations of SU11274 with cisplatin or erlotinib were tested in SCC35/HN5 cell lines. Eighty-four percent of the HNSCC samples showed MET overexpression, whereas 18 of 20 HNSCC cell lines (90%) expressed MET. HGF overexpression was present in 45% of HNSCC. MET inhibition with SU11274/PF-2341066 abrogated MET signaling, cell viability, motility/migration in vitro, and tumor angiogenesis in vivo. Mutational analysis of 66 tumor tissues and 8 cell lines identified novel mutations in the semaphorin (T230M/E168D/N375S), juxtamembrane (T1010I/R988C), and tyrosine kinase (T1275I/V1333I) domains (incidence: 13.5%). Increased MET gene copy number was present with >10 copies in 3 of 23 (13%) tumor tissues. A greater-than-additive inhibition of cell growth was observed when combining a MET inhibitor with cisplatin or erlotinib and synergy may be mediated via erbB3/AKT signaling. MET is functionally important in HNSCC with prominent overexpression, increased gene copy number, and mutations. MET inhibition abrogated MET functions, including proliferation, migration/motility, and angiogenesis. MET is a promising, novel target for HNSCC and combination approaches with cisplatin or EGFR inhibitors should be explored.

Paxillin is a target for somatic mutations in lung cancer: implications for cell growth and invasion

Lung cancer is characterized by abnormal cell growth and invasion, and the actin cytoskeleton plays a major role in these processes. The focal adhesion protein paxillin is a target of a number of oncogenes involved in key signal transduction and important in cell motility and migration. In lung cancer tissues, we have found that paxillin was highly expressed (compared with normal lung), amplified (12.1%, 8 of 66) and correlated with increased MET and epidermal growth factor receptor (EGFR) gene copy numbers, or mutated (somatic mutation rate of 9.4%, 18 of 191). Paxillin mutations (19 of 21) were clustered between LD motifs 1 and 2 and the LIM domains. The most frequent point mutation (A127T) enhanced lung cancer cell growth, colony formation, focal adhesion formation, and colocalized with Bcl-2 in vitro. Gene silencing from RNA interference of mutant paxillin led to reduction of cell viability. A murine in vivo xenograft model of A127T paxillin showed an increase in tumor growth, cell proliferation, and invasion. These results establish an important role for paxillin in lung cancer.

Randomized trial of filgrastim versus chemotherapy and filgrastim mobilization of hematopoietic progenitor cells for rescue in autologous transplantation

Peripheral blood cell (PBC) rescue has become the mainstay for autologous transplantation in patients with lymphoma, multiple myeloma, and solid tumors. Different methods of hematopoietic progenitor cell (HPC) mobilization are in use without an established standard. Forty-seven patients with relapsed or refractory lymphoma received salvage chemotherapy and were randomized to have HPC mobilization using filgrastim [granulocyte-colony-stimulating factor (G-CSF)] alone for 4 days at 10 microg/kg per day (arm A) or cyclophosphamide (5 g/m(2)) and G-CSF at 10 microg/kg per day until hematologic recovery (arm B). Engraftment and ease of PBC collection were primary outcomes. All patients underwent the same high-dose chemotherapy followed by reinfusion of PBCs. There were no differences in median time to neutrophil engraftment (11 days in both arms; P =.5) or platelet engraftment (14 days in arm A, 13 days in arm B; P =.35). Combined chemotherapy and G-CSF resulted in higher CD34(+) cell collection than G-CSF alone (median, 7.2 vs 2.5 x 10(6) cells/kg; P =.004), but this did not impact engraftment. No differences were found in other PBC harvest outcomes or resource utilization measures. A high degree of tumor contamination, as studied by consensus CDR3 polymerase chain reaction of the mobilized PBCs, was present in both arms (92% in arm A vs 90% in arm B; P = 1). No differences were found in overall survival or progression-free survival at a median follow-up of 21 months. This randomized trial provides clinical evidence that the use of G-CSF alone is adequate for HPC mobilization, even in heavily pretreated patients with relapsed lymphoma.

Randomized trial of peripheral blood progenitor cell vs bone marrow as hematopoietic support for high-dose chemotherapy in patients with non-Hodgkin's lymphoma and Hodgkin's disease: a clinical and molecular analysis

Filgrastim (r-metHuG-CSF)-mobilized peripheral blood progenitor cells (PBPC) and unstimulated bone marrow (BM) were evaluated and compared for reconstitution after high-dose chemotherapy in patients with relapsed Hodgkin's disease (HD) or non-Hodgkin's lymphoma (NHL) with respect to engraftment, overall and relapse-free survival, and contamination by lymphoma cells using molecular analysis of immunoglobulin gene rearrangements. Forty-four patients with either NHL or HD underwent autologous transplantation after high-dose chemotherapy. Patients were randomized to receive either Filgrastim-mobilized PBPC (n = 15) or unstimulated BM (n = 14). An additional 15 patients received PBPC without randomization because of a recent history of marrow involvement by lymphoma. Use of PBPC was associated with faster neutrophil engraftment than BM (11 vs 14 days to an absolute neutrophil count >0.5 x 10(9)/l, P = 0.04), but without any difference in platelet engraftment, infectious complications, or overall or event-free survival. Both BM (65%) and PBPC (73%) were frequently contaminated by tumor cells as assessed by CDR3 analysis. Patients with negative polymerase chain reaction analysis of a BM sample during the study had a trend towards an improved survival; however, BM involvement by disease had no impact on the ability to mobilize or collect PBPC. We conclude that PBPC are as effective as BM in reconstituting hematopoiesis after high-dose chemotherapy and that both products are frequently contaminated by sequences marking the malignant clone.

High degree of occult tumor contamination in bone marrow and peripheral blood stem cells of patients undergoing autologous transplantation for non-Hodgkin's lymphoma

Twenty patients with non-Hodgkin's lymphoma (NHL), primarily intermediate-and high-grade, were evaluated for evidence of bone marrow (BM) or peripheral blood stem cell (PBSC) lymphoma contamination using tumor-specific oligonucleotide-polymerase chain reaction (TSO-PCR). Patients were enrolled in a single-institution study comparing PBSC and bone marrow transplantation (BMT) for relapsed NHL. A molecular marker (CDR3 rearrangement, T cell beta receptor [TC beta R] rearrangement, or BCL-2/IgH rearrangement) was identified from analysis of the diagnostic tissue in 17 of 20 patients. Prior to undergoing BMT, 14 of 17 patients had PCR evidence of lymphoma involvement of either BM (11/17) or PBSCs (9/11). No decrease was found in the frequency of contamination of PBSCs compared with BM. In one patient, quantitative competitive PCR (C-PCR) identified a three- to tenfold greater quantity of contamination in the BM compared with PBSC. All evaluated patients (6/6) with contamination prior to BMT had persistence of marrow contamination following BMT. Our data demonstrate that TSO-PCR can generate a molecular marker for the majority of patients with intermediate- and high-grade NHL. In addition, we identified a high rate of occult lymphoma involvement in both BM and PBSC. As demonstrated by C-PCR, however, quantitative differences may exist in contamination of BM and PBSCs.