Whole-exome sequencing and immune profiling of early-stage lung adenocarcinoma with fully annotated clinical follow-up

Background

Lung adenocarcinomas (LUADs) lead to the majority of deaths attributable to lung cancer. We performed whole-exome sequencing (WES) and immune profiling analyses of a unique set of clinically annotated early-stage LUADs to better understand the pathogenesis of this disease and identify clinically relevant molecular markers.

Methods

We performed WES of 108 paired stage I-III LUADs and normal lung tissues using the Illumina HiSeq 2000 platform. Ten immune markers (PD-L1, PD-1, CD3, CD4, CD8, CD45ro, CD57, CD68, FOXP3 and Granzyme B) were profiled by imaging-based immunohistochemistry (IHC) in a subset of LUADs (n = 92). Associations among mutations, immune markers and clinicopathological variables were analyzed using ANOVA and Fisher's exact test. Cox proportional hazards regression models were used for multivariate analysis of clinical outcome.

Results

LUADs in this cohort exhibited an average of 243 coding mutations. We identified 28 genes with significant enrichment for mutation. SETD2-mutated LUADs exhibited relatively poor recurrence- free survival (RFS) and mutations in STK11 and ATM were associated with poor RFS among KRAS-mutant tumors. EGFR, KEAP1 and PIK3CA mutations were predictive of poor response to adjuvant therapy. Immune marker analysis revealed that LUADs in smokers and with relatively high mutation burdens exhibited increased levels of immune markers. Analysis of immunophenotypes revealed that LUADs with STK11 mutations exhibited relatively low levels of infiltrating CD4+/CD8+ T-cells indicative of a muted immune response. Tumoral PD-L1 was significantly elevated in TP53 mutant LUADs whereas PIK3CA mutant LUADs exhibited markedly down-regulated PD-L1 expression. LUADs with TP53 or KEAP1 mutations displayed relatively increased CD57 and Granzyme B levels indicative of augmented natural killer (NK) cell infiltration.

Conclusion(s)

Our study highlights molecular and immune phenotypes that warrant further analysis for their roles in clinical outcomes and personalized immune-based therapy of LUAD.

High prevalence of mutant KRAS in circulating exosome-derived DNA from early-stage pancreatic cancer patients

Background

Exosomes arise from viable cancer cells and may reflect a different biology than circulating cell-free DNA (cfDNA) shed from dying tissues. We compare exosome-derived DNA (exoDNA) to cfDNA in liquid biopsies of patients with pancreatic ductal adenocarcinoma (PDAC).

Patients and methods

Patient samples were obtained between 2003 and 2010, with clinically annotated follow up to 2015. Droplet digital PCR was performed on exoDNA and cfDNA for sensitive detection of KRAS mutants at codons 12/13. A cumulative series of 263 individuals were studied, including a discovery cohort of 142 individuals: 68 PDAC patients of all stages; 20 PDAC patients initially staged with localized disease, with blood drawn after resection for curative intent; and 54 age-matched healthy controls. A validation cohort of 121 individuals (39 cancer patients and 82 healthy controls) was studied to validate KRAS detection rates in early-stage PDAC patients. Primary outcome was circulating KRAS status as detected by droplet digital PCR. Secondary outcomes were disease-free and overall survival.

Results

KRAS mutations in exoDNA, were identified in 7.4%, 66.7%, 80%, and 85% of age-matched controls, localized, locally advanced, and metastatic PDAC patients, respectively. Comparatively, mutant KRAS cfDNA was detected in 14.8%, 45.5%, 30.8%, and 57.9% of these individuals. Higher exoKRAS MAFs were associated with decreased disease-free survival in patients with localized disease. In the validation cohort, mutant KRAS exoDNA was detected in 43.6% of early-stage PDAC patients and 20% of healthy controls.

Conclusions

Exosomes are a distinct source of tumor DNA that may be complementary to other liquid biopsy DNA sources. A higher percentage of patients with localized PDAC exhibited detectable KRAS mutations in exoDNA than previously reported for cfDNA. A substantial minority of healthy samples demonstrated mutant KRAS in circulation, dictating careful consideration and application of liquid biopsy findings, which may limit its utility as a broad cancer-screening method.

ZEB1 induces LOXL2-mediated collagen stabilization and deposition in the extracellular matrix to drive lung cancer invasion and metastasis

Lung cancer is the leading cause of cancer-related death, primarily due to distant metastatic disease. Metastatic lung cancer cells can undergo an epithelial-to-mesenchymal transition (EMT) regulated by many transcription factors, including double-negative feedback loop between the microRNA-200 (miR-200) family and ZEB1, but the precise mechanisms by which ZEB1-dependent EMT promotes malignancy remain largely undefined. While the cell-intrinsic effects of EMT are important for tumor progression, the reciprocal dynamic crosstalk between mesenchymal cancer cells and the extracellular matrix (ECM) is equally critical in regulating invasion and metastasis. Investigating the collaborative effect of EMT and ECM in the metastatic process reveals increased collagen deposition in metastatic tumor tissues as a direct consequence of amplified collagen gene expression in ZEB1-activated mesenchymal lung cancer cells. Additionally, collagen fibers in metastatic lung tumors exhibit greater linearity and organization as a result of collagen crosslinking by the lysyl oxidase (LOX) family of enzymes. Expression of the LOX and LOXL2 isoforms is directly regulated by miR-200 and ZEB1, respectively, and their upregulation in metastatic tumors and mesenchymal cell lines is coordinated to that of collagen. Functionally, LOXL2, as opposed to LOX, is the principle isoform that crosslinks and stabilizes insoluble collagen deposition in tumor tissues. In turn, focal adhesion formation and FAK/SRC signaling is activated in mesenchymal tumor cells by crosslinked collagen in the ECM. Our study is the first to validate direct regulation of LOX and LOXL2 by the miR-200/ZEB1 axis, defines a novel mechanism driving tumor metastasis, delineates collagen as a prognostic marker, and identifies LOXL2 as a potential therapeutic target against tumor progression.

Minimally invasive genomic and transcriptomic profiling of visceral cancers by next-generation sequencing of circulating exosomes

BACKGROUND

The ability to perform comprehensive profiling of cancers at high resolution is essential for precision medicine. Liquid biopsies using shed exosomes provide high-quality nucleic acids to obtain molecular characterization, which may be especially useful for visceral cancers that are not amenable to routine biopsies.

PATIENTS AND METHODS

We isolated shed exosomes in biofluids from three patients with pancreaticobiliary cancers (two pancreatic, one ampullary). We performed comprehensive profiling of exoDNA and exoRNA by whole genome, exome and transcriptome sequencing using the Illumina HiSeq 2500 sequencer. We assessed the feasibility of calling copy number events, detecting mutational signatures and identifying potentially actionable mutations in exoDNA sequencing data, as well as expressed point mutations and gene fusions in exoRNA sequencing data.

RESULTS

Whole-exome sequencing resulted in 95%-99% of the target regions covered at a mean depth of 133-490×. Genome-wide copy number profiles, and high estimates of tumor fractions (ranging from 56% to 82%), suggest robust representation of the tumor DNA within the shed exosomal compartment. Multiple actionable mutations, including alterations in NOTCH1 and BRCA2, were found in patient exoDNA samples. Further, RNA sequencing of shed exosomes identified the presence of expressed fusion genes, representing an avenue for elucidation of tumor neoantigens.

CONCLUSIONS

We have demonstrated high-resolution profiling of the genomic and transcriptomic landscapes of visceral cancers. A wide range of cancer-derived biomarkers could be detected within the nucleic acid cargo of shed exosomes, including copy number profiles, point mutations, insertions, deletions, gene fusions and mutational signatures. Liquid biopsies using shed exosomes has the potential to be used as a clinical tool for cancer diagnosis, therapeutic stratification and treatment monitoring, precluding the need for direct tumor sampling.

LZTFL1 suppresses lung tumorigenesis by maintaining differentiation of lung epithelial cells

Lung cancer is the leading cause of cancer-related death in the United States, and metastatic behavior is largely responsible for this mortality. Mutations in multiple ‘driver' oncogenes and tumor suppressors are known to contribute to the lung tumorigenesis and in some cases represent therapeutic targets. Leucine Zipper Transcription Factor-like 1 (LZTFL1) is located in the chromosome region 3p21.3 where allelic loss and genetic alterations occur early and frequently in lung cancers. Previously, we found that LZTFL1 is downregulated in epithelial tumors, including lung cancer, and functions as a tumor suppressor in gastric cancers. However, the functional role of LZTFL1 in lung oncogenesis is undefined. We show here that downregulation of LZTFL1 expression in non-small cell lung cancer is associated with recurrence and poor survival, whereas re-expression of LZTFL1 in lung tumor cells inhibited extravasation/colonization of circulating tumor cells to the lung and inhibited tumor growth in vivo. Mechanistically, we found that LZTFL1 is expressed in ciliated human bronchial epithelial cells (HBECs) and its expression correlates with HBEC differentiation. LZTFL1 inhibits transforming growth factor β-activated mitogen-activated protein kinase and hedgehog signaling. Alteration of intracellular levels of LZTFL1 resulted in changes of expression of genes associated with epithelial-to-mesenchymal transition (EMT). We conclude that LZTFL1 inhibits lung tumorigenesis, possibly by maintaining epithelial cell differentiation and/or inhibition of signalings that lead to EMT and suggest that reactivation of LZTFL1 expression in tumor cells may be a novel lung cancer therapeutic approach.

Expression profiling stratifies mesothelioma tumors and signifies deregulation of spindle checkpoint pathway and microtubule network with therapeutic implications

BACKGROUND

Malignant pleural mesothelioma (MPM) is a lethal neoplasm exhibiting resistance to most treatment regimens and requires effective therapeutic options. Though an effective strategy in many cancer, targeted therapy is relatively unexplored in MPM because the therapeutically important oncogenic pathways and networks in MPM are largely unknown.

MATERIALS AND METHODS

We carried out gene expression microarray profiling of 53 surgically resected MPMs tumors along with paired normal tissue. We also carried out whole transcriptomic sequence (RNA-seq) analysis on eight tumor specimens. Taqman-based quantitative Reverse-transcription polymerase chain reaction (qRT-PCR), western analysis and immunohistochemistry (IHC) analysis of mitotic arrest deficient-like 1 (MAD2L1) was carried out on tissue specimens. Cell viability assays of MPM cell lines were carried out to assess sensitivity to specific small molecule inhibitors.

RESULTS

Bioinformatics analysis of the microarray data followed by pathway analysis revealed that the mitotic spindle assembly checkpoint (MSAC) pathway was most significantly altered in MPM tumors with upregulation of 18 component genes, including MAD2L1 gene. We validated the microarray data for MAD2L1 expression using quantitative qRT-PCR and western blot analysis on tissue lysates. Additionally, we analyzed expression of the MAD2L1 protein by IHC using an independent tissue microarray set of 80 MPM tissue samples. Robust clustering of gene expression data revealed three novel subgroups of tumors, with unique expression profiles, and showed differential expression of MSAC pathway genes. Network analysis of the microarray data showed the cytoskeleton/spindle microtubules network was the second-most significantly affected network. We also demonstrate that a nontaxane small molecule inhibitor, epothilone B, targeting the microtubules have great efficacy in decreasing viability of 14 MPM cell lines.

CONCLUSIONS

Overall, our findings show that MPM tumors have significant deregulation of the MSAC pathway and the microtubule network, it can be classified into three novel molecular subgroups of potential therapeutic importance and epothilone B is a promising therapeutic agent for MPM.

TGFBI expression is an independent predictor of survival in adjuvant-treated lung squamous cell carcinoma patients

BACKGROUND

Transforming growth factor β-induced protein (TGFBI) is a secreted protein that mediates cell anchoring to the extracellular matrix. This protein is downregulated in lung cancer, and when overexpressed, contributes to apoptotic cell death. Using a small series of stage IV non-small cell lung cancer (NSCLC) patients, we previously suggested the usefulness of TGFBI as a prognostic and predictive factor in chemotherapy-treated late-stage NSCLC. In order to validate and extend these results, we broaden the analysis and studied TGFBI expression in a large series of samples obtained from stage I-IV NSCLC patients.

METHODS

TGFBI expression was assessed by immunohistochemistry in 364 completely resected primary NSCLC samples: 242 adenocarcinomas (ADCs) and 122 squamous cell carcinomas (SCCs). Kaplan-Meier curves, log-rank tests and the Cox proportional hazards model were used to analyse the association between TGFBI expression and survival.

RESULTS

High TGFBI levels were associated with longer overall survival (OS, P<0.001) and progression-free survival (PFS, P<0.001) in SCC patients who received adjuvant platinium-based chemotherapy. Moreover, multivariate analysis demonstrated that high TGFBI expression is an independent predictor of better survival in patients (OS: P=0.030 and PFS: P=0.026).

CONCLUSIONS

TGFBI may be useful for the identification of a subset of NSCLC who may benefit from adjuvant therapy.

The impact of phosphorylated AMP-activated protein kinase expression on lung cancer survival

BACKGROUND

The aim of this study is to investigate the prognostic role of phosphorylated AMP-activated protein kinase (pAMPK) in surgically resected non-small-cell lung cancer (NSCLC).

METHODS

Immunohistochemical staining of pAMPK was carried out on tissue microarrays containing 463 samples obtained from patients with NSCLC and correlated with clinicopathological characteristics and survival.

RESULTS

pAMPK expression levels were significantly higher in never smokers versus former smokers versus current smokers (P=0.045). A positive pAMPK expression was associated with increased overall survival (OS) and recurrence-free survival (RFS) (P=0.0009 and P=0.0007, respectively). OS and RFS were statistically superior in pAMPK-positive than in pAMPK-negative patients with adenocarcinoma (ADC; median OS: 5.6 and 4.2 years, respectively, P=0.0001; median RFS: 5.0 and 2.4 years, respectively, P=0.001), whereas they were similar in those patients with squamous cell carcinoma. Multivariate analysis confirmed that pAMPK positivity was associated with OS [hazard ratio (HR)=0.574, 95% confidence interval (CI) 0.418-0.789, P=0.0006) and RFS (HR=0.608, 95% CI 0.459-0.807, and P=0.0006), independent of clinical covariates.

CONCLUSIONS

High pAMPK expression levels are associated with increased survival in patients with NSCLC, especially those with ADC. Our results support further evaluation of AMP-activated protein kinase as a potential prognostic and therapeutic target for lung cancer.

SSTR2-based reporters for assessing gene transfer into non-small cell lung cancer: evaluation using an intrathoracic mouse model

The most common cause of cancer-related deaths in North America is lung cancer, 85% of which is non-small cell lung cancer (NSCLC). Gene therapy is a promising approach, but has been hindered by lack of methods for localizing and quantifying gene expression in vivo. Human somatostatin receptor subtype-2 (SSTR2)-based reporters can be used to follow gene expression in vivo using ligands with greater affinity for this subtype. NSCLCs can express SSTR subtypes, which may interfere with SSTR2-based reporters. We assessed whether a SSTR2-based reporter can serve as a reporter of gene transfer into NSCLCs. SSTR subtype expression was assessed in NSCLC cell lines A549, H460, and H1299 using RT-PCR. After infection with an adenovirus containing hemagglutinin-A-tagged-SSTR2 (Ad-HA-SSTR2) or control insert, expression was assessed by immunologic techniques and binding to clinically-approved (111)In-octreotide. In vivo, after magnetic resonance (MR) imaging, intrathoracic H460 tumors were injected with Ad-HA-SSTR2 or control virus (n = 6 mice/group) under ultrasound guidance. Intravenous injection of (111)In-octreotide 2 days later was followed by planar and single-photon emission computed tomography (SPECT) imaging. Biodistribution into tumors was assessed in vivo using anatomic MR and functional gamma-camera images and ex vivo using excised organs/tumors. In human lung tumor samples (n = 70), SSTR2 expression was assessed using immunohistochemistry. All three NSCLC cell lines expressed different SSTR subtypes, but none expressed SSTR2. Upon Ad-HA-SSTR2 infection, HA-SSTR2 expression was seen in all three cell lines using antibodies targeting the HA domain or (111)In-octreotide targeting the receptor domain (p < 0.05). Intrathoracic tumors infected with Ad-HA-SSTR2 were clearly visible by gamma-camera imaging; expression was quantified by both in vivo and ex vivo biodistribution analysis and demonstrated greater uptake in tumors infected with Ad-HA-SSTR2 compared with control virus (p < 0.05). Immunohistochemistry found that 78% of NSCLCs are negative for and 13% have low levels of SSTR2 expression. It is concluded that SSTR2-based reporters can serve as reporters of gene transfer into NSCLCs.

Epidermal growth factor receptor regulates MET levels and invasiveness through hypoxia-inducible factor-1alpha in non-small cell lung cancer cells

Recent studies have established that amplification of the MET proto-oncogene can cause resistance to epidermal growth factor receptor (EGFR) tyrosine kinase inhibitors (TKIs) in non-small cell lung cancer (NSCLC) cell lines with EGFR-activating mutations. The role of non-amplified MET in EGFR-dependent signaling before TKI resistance, however, is not well understood. Using NSCLC cell lines and transgenic models, we demonstrate here that EGFR activation by either mutation or ligand binding increases MET gene expression and protein levels. Our analysis of 202 NSCLC patient specimens was consistent with these observations: levels of MET were significantly higher in NSCLC with EGFR mutations than in NSCLC with wild-type EGFR. EGFR regulation of MET levels in cell lines occurred through the hypoxia-inducible factor (HIF)-1alpha pathway in a hypoxia-independent manner. This regulation was lost, however, after MET gene amplification or overexpression of a constitutively active form of HIF-1alpha. EGFR- and hypoxia-induced invasiveness of NSCLC cells, but not cell survival, were found to be MET dependent. These findings establish that, absent MET amplification, EGFR signaling can regulate MET levels through HIF-1alpha and that MET is a key downstream mediator of EGFR-induced invasiveness in EGFR-dependent NSCLC cells.

Phase II randomized study of biomarker-directed treatment for non-small cell lung cancer (NSCLC): The BATTLE (Biomarker-Integrated Approaches of Targeted Therapy for Lung Cancer Elimination) clinical trial program

8024

Background: Treatment for patients (pts) with recurrent NSCLC has limited efficacy despite the use of new targeted agents. Identifying biomarkers to predict tumor response will help personalize therapy for individuals. Methods: Eligible pts had prior chemotherapy, ECOG PS 0–2, and when enrolled, required 2 fresh core needle biopsy specimens to test 11 biomarkers related to 4 molecular pathways in NSCLC: EGFR, Kras, and Braf gene mutation (PCR-based sequencing), EGFR and Cyclin D1 copy number analyses (FISH), and 6 proteins via IHC (VEGF/R and RXR receptors/Cyclin D1). Based on eligibility and tumor biomarker analyses, pts were randomized into 1 of 4 treatments: erlotinib (E) 150 mg qd; sorafenib 400 mg bid, vandetanib 300 mg qd; E 150 mg + bexarotene 400 mg/m2 qd. The primary endpoint is 8-week progression-free status. The first 97 pts were equally randomized, with subsequent pts adaptively randomized under a Bayesian framework. Results: Since 11/2006, 227 pts have been enrolled and 171 randomized and treated (median age 62 yrs, 89 males, 137 Caucasians, 11 Asians, 107 former and 38 never smokers). Accrual has proceeded well (average 9 pts per month). 112 of the biopsied lesions were lung, with a pneumothorax rate of 12.1% (15 of 124 pts; grade 1–2 only; lung, mediastinal and pleural sites). 168 pts (74%) have complete biomarker profiles and 7 (3%) have partial. Histology: adenocarcinoma (75%), squamous (11%), large cell (13%). Mutation frequency was 19% EGFR, 15.4% Kras, and 2.9% Braf. 2 tumors contained both EGFR and Kras mutations, and 2 cases had both Kras and Braf mutations. EGFR polysomy by FISH was 36.4%, and gene amplification 21%. Cyclin D1 amplification was 16.3%. Treatment-related adverse events (grade 3 or more) were 6.5%. Conclusions: We have demonstrated that biopsies are safe and feasible for biomarker-directed studies. The study continues enrollment to 200 evaluable pts at which point the results will be unblinded. BATTLE is one of the first studies in advanced lung cancer to prospectively utilize biomarker analysis of fresh biopsies to direct pt treatment, and is a step towards personalizing therapy in NSCLC. Supported by grant DoD W81XWH-6–1-0303.

No significant financial relationships to disclose.

Integrating microRNA and mRNA expression profiling using a novel algorithm identified a small set of unique genes upregulated in malignant pleural mesothelioma (MPM)

e22111

Background: We employed a global profiling strategy using miRNA microarrays in MPM cell lines and archival tumor tissue. Methods: We isolated total RNA from 4 MPM cell lines, 2 control cell lines, and 16 tissue specimens from patients with resected MPM (n=8) and normal counterpart (n=8) patients as controls. Total RNA was labeled with Cyanine 3, then hybridized with Agilent human miRNA microarray v1 slides. Results: Preliminary miRNA profiles show up-regulation of 44 versus down-regulation of 29 miRNA's in MSTO-211H cancer cells compared to HCT-4012 (pleural telomerase-transformed control). Profiling of 16 tissue specimens (8 normal vs 8 MPM) revealed down-regulation of 11 miRNA's in MPM tumor tissue. To focus on relevant miRNA that regulate genes involved in carcinogenesis and progression, we identified > 1000 unique genes using the online targetscan 4.2 program ( http://www.targetscan.org ), which predicts biological targets of miRNAs by identifying the presence of conserved 8-mer and 7-mer sites that match the seed region of each miRNA. We then explored a novel screening strategy, which combines mRNA expression dataset with the miRNA dataset, to narrow the list of relevant miRNA's. We conducted gene expression profiling on the cell lines and MPM tissue samples with Affymetrix U133 plus 2.0 chips. Bioinformatic analysis was conducted with MeV: MultiExperiment Viewer software, data reduction techniques (Correspondance Analysis), hierarchical clustering methods, and Serial Analysis for Microarray (SAM), and showed up-regulation of ∼300 genes in MPM compared to normal tissues. We then computed of the ∼300 mRNA's up-regulated in MPM only 32 are recognized by the 11 down-regulated miRNA's using the targetscan 4.2 algorithm. Most of the miRNA's regulate single messages while ∼20 % of the messages are regulated by more than 1 miRNA's. Some of these targets include Ets variant 1 and Protein kinase C - epsilon. Conclusions: This innovative approach of selecting highly relevant miRNA is feasible and enables discovery of novel genes based on their ability to be bound by single or multiple miRNA's. Validation of our profiling studies using real-time PCR and protein analysis methods will be presented.

No significant financial relationships to disclose.

Phase II pilot study of neoadjuvant docetaxel and cisplatin followed by adjuvant erlotinib in patients with stage I-III non-small cell lung cancer (NSCLC)

7566

Background: Pts with early stage NSCLC, especially with nodal disease, have a poor prognosis despite curative intent therapy. It is unclear which pts may derive the benefit of chemotherapy. The primary endpoint of the study was to assess the tolerability of the regimen. In addition, the clinical response of the chemotherapy regimen as well as tumor biomarkers modulation will be examined. Methods: Pts had previously untreated, potentially surgically resectable, stage I-III NSCLC with ECOG performance status (PS) 0–1 and adequate laboratory parameters. After baseline tissue was obtained, chemotherapy was administered (docetaxel [T] 75 mg/m2 and cisplatin [P] 80 mg/m2 every 3 wks) for 3 cycles. Subsequently, pts underwent restaging, then planned definitive therapy with surgical resection. Pts were then offered treatment for 1 year with erlotinib (E) 150 mg PO daily. Bronchoscopic biopsies were performed at 6 months and 1 year post- surgery. Results: 41 pts were enrolled between 2/07 and 11/08. 3 were not eligible and did not receive treatment. Of the 38 eligible pts: median age was 65 years (42–80); 24 (63.2%) were male; 26 (68%) were PS 1. Stage IB 18% (7), IIB 37% (14), IIIA 39% (15), IIIB 5% (2). 31 pts completed all 3 cycles (35 pts completed at least 2 cycles). 32 pts underwent definitive surgical resection with 1 pt pending for surgery. 5 others did not undergo surgery: pneumonia (1), progressive disease (1), definitive chemo-radiation (3). For pts completing at least 2 cycles of chemotherapy, the radiographic response rate was 57% (20) by RECIST criteria with 40% (14) having stable disease. 1 pt had a complete pathologic response. 16 pts have started adjuvant E, 4 have completed 1 yr of treatment. Grade 3/4 toxicities included neutropenia (6 pts) and hypokalemia (4 pts). Blood and tissue specimens will be analyzed to assess sensitivity to chemotherapy. Conclusions: Neoadjuvant T and P is a tolerable and active regimen with an encouraging response rate in stage I- III resectable NSCLC. In addition to clinical characteristics, determining which patients will benefit from chemotherapy by analyzing their tumor biomarkers may help improve overall outcomes of curative lung cancer pts. Supported by grant DoD# W81XWH-07–1-0306.

[Table: see text]

Activated Src kinase is expressed in malignant pleural mesothelioma tumors; dasatinib inhibition leads to cytotoxicity, cell cycle inhibition, and prevention of invasion and migration

7713

Background: Malignant pleural mesothelioma (MPM) is a lethal disease with few effective therapeutic options. We sought to determine whether Src, a non-receptor tyrosine kinase, could be a new therapeutic target in MPM and to establish the potential therapeutic use of pharmacologic Src inhibitors in this disease. Methods: We analyzed four MPM cell lines (MSTO-211H, NCI-H28, NCI-H2052, and NCI- H2452) for immunohistochemical (IHC) expression of total and phosphorylated Src (Tyr 419, Tyr 530). These cell lines were treated with dasatinib, a Src inhibitor, and evaluated for apoptosis, cell cycle analysis, and migration and invasion. Downstream signaling events were studied by Western blot analysis. We also conducted IHC analyses with total Src, phosphorylated Src Tyr 419 (p-Src Tyr 419), and phosphorylated Src Tyr 530 on 46 archived MPM tumor specimens and correlated the biomarker results with the clinical outcome. Results: All four MPM cell lines expressed total and activated Src (p-Src Tyr 419). Three of the four cell lines were sensitive in vitro to cytotoxicity by dasatinib with inhibition of migration and invasion, cell cycle inhibition, and apoptosis. Treatment with dasatinib inhibited several pathways downstream of Src. In the archived MPM tumor specimens, Src protein was highly expressed on IHC analysis in tumor cells, but that expression did not correlate with overall or progression-free survival. However, expression of activated Src (p-Src Tyr 419) on the tumor cell membrane was higher in patients with stage 4 disease; the presence of metastasis correlated with higher membrane (P = 0.03) and cytoplasmic (P = 0.04) expression of p-Src Tyr 419. MPM nodal involvement at N1 was associated with the highest membrane expression of inactive Src (p-Src Tyr 530) (P = 0.02), whereas N2 disease was associated with the lowest expression. No gene mutations in Src exon 12 were found in the cell lines or tumor specimens. Conclusions: Activated Src may have an important role in survival, metastasis, and invasion in MPM, and targeting Src may be an important therapeutic strategy.

No significant financial relationships to disclose.

c-Jun N-terminal kinase is activated in non-small-cell lung cancer and promotes neoplastic transformation in human bronchial epithelial cells

c-Jun N-terminal kinase (JNK) has been reported to either potentiate or inhibit oncogenesis, depending upon the cellular context, but its role in lung neoplasia is unclear. Here we sought to define the role of JNK in lung neoplasia by examining evidence of JNK phosphorylation in non-small-cell lung cancer (NSCLC) biopsy samples and by using genetic and pharmacologic approaches to modulate JNK expression and activity in cultured cells. Immunohistochemical staining for JNK phosphorylation was detected in 114 (45%) of 252 NSCLC biopsy samples and was predominantly nuclear, providing evidence of JNK activation in a subset of NSCLC cases. Introduction of a doxycycline-inducible, constitutively active, mutant mitogen-activated protein kinase kinase 4 (MKK4) into the human bronchial epithelial cell lines BEAS-2B and HB56B increased the cells' proliferation, migration, invasion and clonogenicity. Depletion of JNK in MKK4 mutant-transformed BEAS-2B cells by introduction of JNK1/2 short hairpin RNA reversed the transformed phenotype, indicating that JNK activation is oncogenic and MKK4 confers neoplastic properties in these cells. The proliferation of NSCLC cell lines HCC827 and H2009, in which JNK and its substrate c-Jun are constitutively phosphorylated, was inhibited by SP600125, a JNK kinase inhibitor. We conclude that JNK is activated in a subset of NSCLC biopsy samples and promotes oncogenesis in the bronchial epithelium, suggesting that strategies to inhibit the JNK pathway should be considered for the prevention and treatment of NSCLC.

Clinical significance of HuR expression, an mRNA-binding protein in non-small cell lung cancer (NSCLC)

10098

Background: HuR is a nucleo-cytoplasmic shuttling protein that specifically binds to mRNA that has AU rich (ARE) sites at the 3’end and transports the RNA to the cytoplasm for protein translation. In addition to mRNA transportation, HuR plays a role in mRNA stabilization and protein translation. Preclinical studies have shown mRNA’s of several growth factors, cell-cycle regulators, and transcription-regulating proteins have ARE’s at the 3’end and bound by HuR. However, there has been reported no clinical data on HuR expression in NSCLC. Thus, in the present study, we assessed clinical significance of HuR expression in NSCLC. Patients and Methods: A total of 236 patients with completely resected p-stage I-IIIA, NSCLC, were reviewed, and HuR expression was evaluated immunohistochemically. Results (Table): HuR expression was seen in the nucleus and cytoplasm of tumor cells. Cytoplasmic HuR expression was positively correlated with tumor progression (p-stage, P<0.01), especially nodal metastasis, microvessel density (MVD), and COX-2 expression. Enhanced nuclear HuR expression was also correlated with tumor progression and COX-2 expression, but not with MVD. Positive cytoplasmic HuR expression was a significant factor to predict a poor prognosis in all patients (5-year survival rates: 85% for HuR-negative and 43% for HuR-positive patients; P<0.01) and in any p-stage/histology subset patients. Nuclear HuR expression status was also a significant prognostic factor in all patients, but not in all subsets. A multivariate analysis confirmed that cytoplasmic HuR status was an independent prognostic factor (hazard ratio [95% CI], 4.261 [2.109–8.609]; P<0.001). Conclusions: Cytoplasmic HuR expression was correlated with tumor progression, and was a significant and independent prognostic factor in correlation with enhanced COX-2 expression and increased tumor angiogenesis.

[Table: see text]

No significant financial relationships to disclose.