Integrative proteomic and transcriptomic analysis provides evidence for TrkB (NTRK2) as a therapeutic target in combination with tyrosine kinase inhibitors for non-small cell lung cancer

While several molecular targets have been identified for adenocarcinoma (ACA) of the lung, similar drivers with squamous cell carcinoma (SCC) are sparse. We compared signaling pathways and potential therapeutic targets in lung SCC and ACA tumors using reverse phase proteomic arrays (RPPA) from two independent cohorts of resected early stage NSCLC patients: a testing set using an MDACC cohort (N=140) and a validation set using the Cancer Genome Atlas (TCGA) cohorts. We identified multiple potentially targetable proteins upregulated in SCC, including NRF2, Keap1, PARP, TrkB, and Chk2. Of these potential targets, we found that TrkB also had significant increases in gene expression in SCC as compared to adenocarcinoma. Thus, we next validated the upregulation of TrkB both in vitro and in vivo and found that it was constitutively expressed at high levels in a subset of SCC cell lines. Furthermore, we found that TrkB inhibition suppressed tumor growth, invasiveness and sensitized SCC cells to tyrosine kinase EGFR inhibition in a cell-specific manner.

Taxane-Platin-Resistant Lung Cancers Co-develop Hypersensitivity to JumonjiC Demethylase Inhibitors

Although non-small cell lung cancer (NSCLC) patients benefit from standard taxane-platin chemotherapy, many relapse, developing drug resistance. We established preclinical taxane-platin-chemoresistance models and identified a 35-gene resistance signature, which was associated with poor recurrence-free survival in neoadjuvant-treated NSCLC patients and included upregulation of the JumonjiC lysine demethylase KDM3B. In fact, multi-drug-resistant cells progressively increased the expression of many JumonjiC demethylases, had altered histone methylation, and, importantly, showed hypersensitivity to JumonjiC inhibitors in vitro and in vivo. Increasing taxane-platin resistance in progressive cell line series was accompanied by progressive sensitization to JIB-04 and GSK-J4. These JumonjiC inhibitors partly reversed deregulated transcriptional programs, prevented the emergence of drug-tolerant colonies from chemo-naive cells, and synergized with standard chemotherapy in vitro and in vivo. Our findings reveal JumonjiC inhibitors as promising therapies for targeting taxane-platin-chemoresistant NSCLCs.

The epithelial-to-mesenchymal transition activator ZEB1 initiates a prometastatic competing endogenous RNA network

Epithelial tumor cells undergo epithelial-to-mesenchymal transition (EMT) to gain metastatic activity. Competing endogenous RNAs (ceRNAs) have binding sites for a common set of microRNAs (miRs) and regulate each other's expression by sponging miRs. Here, we address whether ceRNAs govern metastasis driven by the EMT-activating transcription factor ZEB1. High miR-181b levels were correlated with an improved prognosis in human lung adenocarcinomas, and metastatic tumor cell lines derived from a murine lung adenocarcinoma model in which metastasis is ZEB1-driven were enriched in miR-181b targets. ZEB1 relieved a strong basal repression of α1 integrin (ITGA1) mRNA, which in turn upregulated adenylyl cyclase 9 mRNA (ADCY9) by sponging miR181b. Ectopic expression of the ITGA1 3'-untranslated region reversed miR-181b-mediated metastasis suppression and increased the levels of adenylyl cyclase 9 protein (AC9), which promoted tumor cell migration and metastasis. In human lung adenocarcinomas, ITGA1 and ADCY9 levels were positively correlated, and an AC9-activated transcriptomic signature had poor-prognostic value. Thus, ZEB1 initiates a miR-181b-regulated ceRNA network to drive metastasis.

Expression pattern of FGFR2, Grb2 and Plcγ1 acts as a novel prognostic marker of recurrence recurrence-free survival in lung adenocarcinoma

Lung adenocarcinoma is characterized by complex biology involving alterations at the genomic and protein expression levels. FGFR2 mutation and/or amplification are key drivers of disease progression and drug resistance in lung adenocarcinoma patients. These genetic alterations drive oncogenic downstream signalling due to the deregulated activity of the receptor. We have previously reported that wild type FGFR2 provides a binding site for which two proteins, Grb2 and Plcγ1, compete in a concentration-dependent manner. Metastasis and invasion ensue when Plcγ1 prevails on the receptor giving rise to oncogenic outcome in the absence of gene mutation/deletion. The effect of this signalling mechanism on FGFR2-driven lung adenocarcinoma has not previously been considered. In this study we show that fluctuation in the combinatorial expression levels of FGFR2, Grb2 and Plcγ1 modulates cell invasive properties, tumor formation and is linked to recurrence-free survival in 150 lung adenocarcinoma patients. High levels of expression of FGFR2 and Plcγ1 in a low background of Grb2 significantly correlates with poor prognosis. On the other hand, low levels of expression of FGFR2 and Plcγ1 in a high background of Grb2 correlates with favourable prognosis. This study defines the expression pattern of FGFR2, Plcγ1 and Grb2 as a novel prognostic marker in human lung adenocarcinoma. Thus, consideration of the Grb2 and Plcγ1-mediated mechanism of FGFR2 regulation will enhance the therapeutic targeting of aberrant FGFR2 activity to provide the much-needed improvement to the treatment regimen of this high mortality disease.

Genetic mutation of p53 and suppression of the miR-17∼92 cluster are synthetic lethal in non-small cell lung cancer due to upregulation of vitamin D Signaling

Lung cancer is the leading cause of cancer-related fatalities. Recent success developing genotypically targeted therapies, with potency only in well-defined subpopulations of tumors, suggests a path to improving patient survival. We used a library of oligonucleotide inhibitors of microRNAs, a class of posttranscriptional gene regulators, to identify novel synthetic lethal interactions between miRNA inhibition and molecular mechanisms in non-small cell lung cancer (NSCLC). Two inhibitors, those for miR-92a and miR-1226*, produced a toxicity distribution across a panel of 27 cell lines that correlated with loss of p53 protein expression. Notably, depletion of p53 was sufficient to confer sensitivity to otherwise resistant telomerase-immortalized bronchial epithelial cells. We found that both miR inhibitors cause sequence-specific downregulation of the miR-17∼92 polycistron, and this downregulation was toxic only in the context of p53 loss. Mechanistic studies indicated that the selective toxicity of miR-17∼92 polycistron inactivation was the consequence of derepression of vitamin D signaling via suppression of CYP24A1, a rate-limiting enzyme in the 1α,25-dihydroxyvitamin D3 metabolic pathway. Of note, high CYP24A1 expression significantly correlated with poor patient outcome in multiple lung cancer cohorts. Our results indicate that the screening approach used in this study can identify clinically relevant synthetic lethal interactions and that vitamin D receptor agonists may show enhanced efficacy in p53-negative lung cancer patients.

Metastasis is regulated via microRNA-200/ZEB1 axis control of tumour cell PD-L1 expression and intratumoral immunosuppression

Immunosuppression of tumour-infiltrating lymphocytes (TIL) is a common feature of advanced cancer, but its biological basis has remained obscure. We demonstrate here a molecular link between epithelial-to-mesenchymal transition (EMT) and CD8(+) TIL immunosuppression, two key drivers of cancer progression. We show that microRNA-200 (miR-200), a cell-autonomous suppressor of EMT and metastasis, targets PD-L1. Moreover, ZEB1, an EMT activator and transcriptional repressor of miR-200, relieves miR-200 repression of PD-L1 on tumour cells, leading to CD8(+) T-cell immunosuppression and metastasis. These findings are supported by robust correlations between the EMT score, miR-200 levels and PD-L1 expression in multiple human lung cancer datasets. In addition to revealing a link between EMT and T-cell dysfunction, these findings also show that ZEB1 promotes metastasis through a heretofore unappreciated cell non-autonomous mechanism, and suggest that subgroups of patients in whom malignant progression is driven by EMT activators may respond to treatment with PD-L1 antagonists.

Abstract 3772: Developing a molecular understanding of non-small cell lung cancer resistance to standard taxane-platin chemotherapy

Purpose: Non-small cell lung cancer (NSCLC) patients show benefit from neoadjuvant chemotherapy given before surgical resection or adjuvant chemotherapy administered after tumor resection. However, several of these patients still relapse and die with metastatic NSCLC. These relapses represent resistance of the tumors to chemotherapy. NSCLC resistance to standard taxane and platin doublet chemotherapy is a major problem. Identifying and overcoming resistance mechanisms are thus urgently needed and the focus of this research.

Methods: (A) NSCLC cell lines were exposed long term to cycles of paclitaxel + carboplatin in clinically relevant dosage ratios, to select and subsequently characterize resistant cells. (B) Subcutaneous xenografts of parental and resistant cell lines were established in NOD/SCID mice to include expression changes that are retained in vivo. (C) Molecularly and clinically annotated dataset of NSCLC patient tumors obtained after neoadjuvant taxane + platin chemotherapy (N = 66; some had long term disease free survival and some had tumor relapses) were subjected to gene expression and survival analyses.

Results and Significance: NSCLC cell lines NCI-H1299 and NCI-H1355 treated for 16-18 cycles with paclitaxel + carboplatin developed >50 fold resistance. Cells also developed cross-resistance to doxorubicin and vinorelbine. In addition, these resistant cell lines showed decreased response to docetaxel + cisplatin doublet in vivo. Consistent with the literature, cells showed increased expression of multi-drug transporter ABCB1/MDR1. This corresponded to decreased intracellular docetaxel accumulation in resistant cells. Cell line variants showed reversal in resistance when exposed to MDR1 inhibitors or with ABCB1 knockdown. Reversal in both cases was however partial, suggesting additional resistance mechanisms. This was also indicated by repeating long term drug selection in presence of MDR inhibitor, wherein cells still developed resistance. Microarray profiles of resistant cell lines suggested mRNA expression changes in stem cell pathways, epithelial-to-mesenchymal transition (EMT) genes and certain epigenetic modulators. Cross-comparison of gene hits from cell lines and xenografts yielded 14 commonly up-regulated and 21 down-regulated genes that formed a resistance signature from preclinical models. This 35-gene resistance signature could successfully classify neoadjuvant treated patient tumors into two main clusters with significant differences in tumor recurrence and cancer-free survival. Studies are underway to determine whether this signature is purely prognostic or also has a functional role in causing resistance. Such information will provide both clinically useful biomarkers to type tumor response in patients and also potentially new therapeutic targets to overcome standard taxane-platin drug resistance in NSCLC.

Citation Format: Maithili Prafulla Dalvi, Carmen Behrens, Milind Suraokar, Rui Zhong, Brenda Timmons, Luc Girard, Yang Xie, Ignacio Wistuba, John D. Minna. Developing a molecular understanding of non-small cell lung cancer resistance to standard taxane-platin chemotherapy. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 3772. doi:10.1158/1538-7445.AM2014-3772

Abstract 466: LMO1 is a novel oncogene in neuroendocrine lung cancer

Introduction. The aim of the study is to characterize the role of LMO1 in tumorigenesis of neuroendocrine lung cancer. LMO1 is a transcription factor that belongs to the LMO protein family containing the cysteine-rich LIM domains. LMO1 has been demonstrated to function as an important oncogene in the development of T-lineage leukemia and lymphoma. A recent study in neuroblastoma suggests that aberrant overexpression of LMO1 may play a critical role in the development of neuroendocrine cancers. The role of LMO1 in neuroendocrine lung cancer, however, was not investigated.

Experimental Approaches. By analyzing a large panel of cell lines including lung cancer cell lines and normal lung epithelial cells, we compared the relative expression of LMO1 in different subtypes of lung cancers, and examined the correlation of LMO1 expression levels with neuroendocrine differentiation markers. Using in vitro approaches, we investigated the function of LMO1 in regulating lung cancer cell growth. To investigate the clinical significance of LMO1 dysregulation in lung cancer patients, we analyzed the correlation of LMO1 tumor levels with lung cancer patient survival.

Results. We show that LMO1 is significantly overexpressed in small cell lung cancer (SCLC), an aggressive and major subtype of neuroendocrine lung cancers, relative to non-small cell lung cancer (NSCLC) and normal lung cells. In addition, in NSCLC cells, LMO1 mRNA levels are significantly correlated with expression of neuroendocrine differentiation markers. Functional in vitro investigations indicate that LMO1 overexpression significantly promotes growth of cultured lung cancer cells, suggesting its oncogenic function in lung cancer. More strikingly, our investigations of two independent lung cancer patient populations indicate that high tumor LMO1 mRNA level is an independent predictor of poor patient survival.

Conclusions. Altogether, our findings strongly suggest that LMO1 is a neuroendocrine-specific oncogene in lung cancer that plays an important role in determining the cancer aggressiveness. Further studies are certainly warranted to define the mechanisms underlying the oncogenic function of LMO1 in neuroendocrine lung cancer and to further evaluate the clinical significance of LMO1 as a diagnostic and prognostic marker for neuroendocrine lung cancers in prospective studies.

Citation Format: Zhenze Zhao, Xiuye Ma, Xiaojie Yu, Tzu-Hung Hsiao, Yidong Chen, Milind Suraokar, Ignacio Wistuba, John D. Minna, Alexander Pertsemlidis, Liqin Du. LMO1 is a novel oncogene in neuroendocrine lung cancer. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 466. doi:10.1158/1538-7445.AM2014-466

VEGF/VEGFR-2 upregulates EZH2 expression in lung adenocarcinoma cells and EZH2 depletion enhances the response to platinum-based and VEGFR-2-targeted therapy

PURPOSE

To investigate the mechanisms of regulation and role associated with enhancer of zeste homolog 2 (EZH2) expression in lung cancer cells.

EXPERIMENTAL DESIGN

We investigated the mechanisms of EZH2 expression associated with the VEGF/VEGFR-2 pathway. Furthermore, we sought to determine the role of EZH2 in response of lung adenocarcinoma to platinum-based chemotherapy, as well as the effect of EZH2 depletion on VEGFR-2-targeted therapy in lung adenocarcinoma cell lines. In addition, we characterized EZH2 expression in lung adenocarcinoma specimens and correlated it with patients' clinical characteristics.

RESULTS

In this study, we demonstrate that VEGF/VEGFR-2 activation induces expression of EZH2 through the upregulation of E2F3 and hypoxia-inducible factor-1α (HIF1α), and downregulated expression of miR-101. EZH2 depletion by treatment with 3-deazaneplanocin A and knockdown by siRNA decreased the expression of EZH2 and H3K27me3, increased PARP-C level, reduced cell proliferation and migration, and increased sensitivity of the cells to treatment with cisplatin and carboplatin. In addition, high EZH2 expression was associated with poor overall survival in patients who received platinum-based adjuvant therapy, but not in patients who did not receive this therapy. Furthermore, we demonstrated for the first time that the inhibition of EZH2 greatly increased the sensitivity of lung adenocarcinoma cells to the anti-VEGFR-2 drug AZD2171.

CONCLUSION

Our results suggest that the VEGF/VEGFR-2 pathway plays a role in regulation of EZH2 expression via E2F3, HIF1α, and miR-101. EZH2 depletion decreases the malignant potential of lung adenocarcinoma and sensitivity of the cells to both platinum-based and VEGFR-2-targeted therapy.

Radiation-enhanced lung cancer progression in a transgenic mouse model of lung cancer is predictive of outcomes in human lung and breast cancer

PURPOSE

Carcinogenesis is an adaptive process between nascent tumor cells and their microenvironment, including the modification of inflammatory responses from antitumorigenic to protumorigenic. Radiation exposure can stimulate inflammatory responses that inhibit or promote carcinogenesis. The purpose of this study is to determine the impact of radiation exposure on lung cancer progression in vivo and assess the relevance of this knowledge to human carcinogenesis.

EXPERIMENTAL DESIGN

K-ras(LA1) mice were irradiated with various doses and dose regimens and then monitored until death. Microarray analyses were performed using Illumina BeadChips on whole lung tissue 70 days after irradiation with a fractionated or acute dose of radiation and compared with age-matched unirradiated controls. Unique group classifiers were derived by comparative genomic analysis of three experimental cohorts. Survival analyses were performed using principal component analysis and k-means clustering on three lung adenocarcinoma, three breast adenocarcinoma, and two lung squamous carcinoma annotated microarray datasets.

RESULTS

Radiation exposure accelerates lung cancer progression in the K-ras(LA1) lung cancer mouse model with dose fractionation being more permissive for cancer progression. A nonrandom inflammatory signature associated with this progression was elicited from whole lung tissue containing only benign lesions and predicts human lung and breast cancer patient survival across multiple datasets. Immunohistochemical analyses suggest that tumor cells drive predictive signature.

CONCLUSIONS

These results demonstrate that radiation exposure can cooperate with benign lesions in a transgenic model of cancer by affecting inflammatory pathways, and that clinically relevant similarities exist between human lung and breast carcinogenesis.

Abstract 4643: EZH2 promote a malignant phenotype in lung adenocarcinoma and VEGF/VEGFR2 pathways mediates regulation of EZH2 through E2F3/HIF-1α and downregulation of miR-101

Background. EZH2 overexpression has been described in a wide variety of tumors, including lung cancer. EZH2 has been implicated in neoplastic transformation, tumor progression and activation of angiogenesis. The mechanisms associated with the regulation of EZH2 expression in lung cancer cells are mostly unknown. In this study, we investigated the role of EZH2 in cell proliferation/migration and response to chemotherapy in lung adenocarcinoma (LADCa) cell lines. Moreover, we studied the mechanisms of EZH2 regulation associated to the VEGF/VEGFR2 pathway expression.

Methods. LADCa cell lines were inhibited pharmacologically with different doses of DZNep (0, 2.5 and 5μM) and by knockdown of EZH2 by siRNA. EZH2, H3K27me3 and PARP-C expressions were determined by Western-blots (WB). Cisplatin and carboplatin sensitivity (IC50) and proliferation were determined by MTS assay. Cell migration was measured using Boyden chamber assay. After stimulation of cell lines with VEGF-A, EZH2, VEGFR-2, E2F3 and HIF-1α expression were determined using WBs, and EZH2 and miR-101 expressions were determined by quantitative PCR. To study the role of VEGFR-2 and HIF-1α in the regulation of EZH2, we examined the effect of knockdown VEGFR-2 and HIF-1α by siRNA.

Results. We found that inhibition with DZNep and knockdown by siRNA decreased the expression of EZH2, reduced H3K27me3 level, and increased PARP-C levels in LADCa cell lines. Treatment with DZNep and knockdown of EZH2 significantly increased sensitivity to cisplatin and carboplatin (p<0.05) by MTS assay of LADCa cell lines. Knockdown of EZH2 reduced significantly cell proliferation and migration of LADCa cell lines (p<0.05). VEGF stimulation induced expression of EZH2 and H3K27me3 levels. Concomitantly, we found that stimulation with VEGF induced expression of E2F3 and HIF-1α, and downregulation of miR-101. This phenomenon was observed only in LADCa cell lines expressing VEGFR-2, and not in cell lines with low or lack of expression of VEGFR-2. The increased expression of EZH2, E2F3 and HIF-1α, and the down-regulation of miR-101 in response to VEGF, were reduced by knocking down VEGFR-2 and to a lesser degree by knocking down HIF-1α in LADCa.

Conclusion. Our in vitro findings suggest that EZH2 overexpression may promote a more malignant phenotype of lung adenocarcinoma. The pharmacologic inhibition with DZNep and knockdown of EZH2 by siRNA increased sensitivity of LADCa cell lines to cisplatin and carboplatin, and reduced cell migration capabilities. Our results suggest that VEGF/VEGFR-2 axis plays a role in the regulation of EZH2 through E2F3/HIF-1α and miR-101 regulations. EZH2 is a potential therapeutic target in lung cancer that regulates the epigenome to overcome drug resistance. (Supported in part by grants DoD PROSPECT W81XWH-07-1-0306, NCI/UT Lung SPORE 5P50CA70907-11, and Becas Chile)

Citation Format: Erick M. Riquelme, Carmen Berhens, Milind Suraokar, Ignacio I. Wistuba. EZH2 promote a malignant phenotype in lung adenocarcinoma and VEGF/VEGFR2 pathways mediates regulation of EZH2 through E2F3/HIF-1α and downregulation of miR-101. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 4643. doi:10.1158/1538-7445.AM2013-4643

Abstract 1202: Expression signature for classification of non-small cell lung cancer

Background: Approximately 85-90% of lung cancers are non-small cell lung cancers (NSCLCs) consisting of adenocarcinoma (ADC) and squamous cell carcinoma (SCC) and several rare types including undifferentiated large cell carcinomas. Most NSCLCs are diagnosed from small biopsies or cytology materials and, even with the use of immunostains, some cannot be classified further and are referred to as NSCLC - not otherwise specified (NSCLC-NOS). For several clinically relevant reasons and for selection of therapy the correct identification of NSCLC typing is important.

Specific Aim: To develop a highly specific and sensitive RNA expression signature as an adjunct test for routine pathological classification.

Methods: A microarray dataset of 263 resected NSCLC cases (183 ADC, 80 SCC) obtained from MD Anderson Cancer Center and profiled on the Illumina WG-6 V3 platform was used as the learning set. The Cancer Genome Atlas (TCGA; http://cancergenome.nih.gov/) microarray dataset (105 ADC, 205 SCC), which were profiled on an RNAseq platform, was used as the validation set. Histologic typing on the TCGA specimens was performed by light microscopy according to the WHO classification. Materials for immunostaining were not always available.

Results: We developed a 44-gene signature which contained many of the genes encoding proteins routinely used in immunostains for NSCLC typing, including TP63, TTF1, SOX2, and several high molecular weight keratins. For testing, a nearest neighbor approach with Pearson metric was used, which yielded two scores (Pearson correlations, ranging from -1 to +1) for ADC and SCC histologies. Scores above 0.4 were considered positive for the respective tumor type, while values below 0.4 were considered to be null (equivalent to poorly/undifferentiated histology). The learning set had 7% discrepancies for the major tumor type and 1% was scored as null. Initial validation of the TCGA data indicated a relatively high percentage of discrepancies (10% of ADC, 12% of SCC). After discussions with TCGA reference pathologists Drs. Travis and Rekhtman and further evaluation by them a revised pathological classification was generated, which included 25 NSCLC-NOS diagnoses. The discrepancies were reduced to 9 % and 4 % for ADC and SCC respectively. The NSCLC-NOS cases were classified as ADC, SCC or null types.

Future plans: We are utilizing the expression signature to develop and validate a quantitative nuclease protection assay (qNPA by High Throughput Genomics) that can be applied to small biopsies and 5-micron sections of archival paraffin embedded formalin fixed material in a 96 well format.

Summary and significance: The development and application of a sensitive and specific molecular signature for the classification of NSCLC provides an important adjunct test for routine pathological diagnosis, especially for application to small specimens (which constitute about 70% of current diagnostic lung cancer samples).

Citation Format: Luc Girard, Ignacio Wistuba, William D. Travis, Natasha Rekhtman, Milind Suraokar, Carmen Behrens, John D. Minna, Adi F. Gazdar. Expression signature for classification of non-small cell lung cancer. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 1202. doi:10.1158/1538-7445.AM2013-1202

A 12-gene set predicts survival benefits from adjuvant chemotherapy in non-small cell lung cancer patients

PURPOSE

Prospectively identifying who will benefit from adjuvant chemotherapy (ACT) would improve clinical decisions for non-small cell lung cancer (NSCLC) patients. In this study, we aim to develop and validate a functional gene set that predicts the clinical benefits of ACT in NSCLC.

EXPERIMENTAL DESIGN

An 18-hub-gene prognosis signature was developed through a systems biology approach, and its prognostic value was evaluated in six independent cohorts. The 18-hub-gene set was then integrated with genome-wide functional (RNAi) data and genetic aberration data to derive a 12-gene predictive signature for ACT benefits in NSCLC.

RESULTS

Using a cohort of 442 stage I to III NSCLC patients who underwent surgical resection, we identified an 18-hub-gene set that robustly predicted the prognosis of patients with adenocarcinoma in all validation datasets across four microarray platforms. The hub genes, identified through a purely data-driven approach, have significant biological implications in tumor pathogenesis, including NKX2-1, Aurora Kinase A, PRC1, CDKN3, MBIP, and RRM2. The 12-gene predictive signature was successfully validated in two independent datasets (n = 90 and 176). The predicted benefit group showed significant improvement in survival after ACT (UT Lung SPORE data: HR = 0.34, P = 0.017; JBR.10 clinical trial data: HR = 0.36, P = 0.038), whereas the predicted nonbenefit group showed no survival benefit for 2 datasets (HR = 0.80, P = 0.70; HR = 0.91, P = 0.82).

CONCLUSIONS

This is the first study to integrate genetic aberration, genome-wide RNAi data, and mRNA expression data to identify a functional gene set that predicts which resectable patients with non-small cell lung cancer will have a survival benefit with ACT.

BSTA promotes mTORC2-mediated phosphorylation of Akt1 to suppress expression of FoxC2 and stimulate adipocyte differentiation

Phosphorylation and activation of Akt1 is a crucial signaling event that promotes adipogenesis. However, neither the complex multistep process that leads to activation of Akt1 through phosphorylation at Thr³⁰⁸ and Ser⁴⁷³ nor the mechanism by which Akt1 stimulates adipogenesis is fully understood. We found that the BSD domain-containing signal transducer and Akt interactor (BSTA) promoted phosphorylation of Akt1 at Ser⁴⁷³ in various human and murine cells, and we uncovered a function for the BSD domain in BSTA-Akt1 complex formation. The mammalian target of rapamycin complex 2 (mTORC2) facilitated the phosphorylation of BSTA and its association with Akt1, and the BSTA-Akt1 interaction promoted the association of mTORC2 with Akt1 and phosphorylation of Akt1 at Ser⁴⁷³ in response to growth factor stimulation. Furthermore, analyses of bsta gene-trap murine embryonic stem cells revealed an essential function for BSTA and phosphorylation of Akt1 at Ser⁴⁷³ in promoting adipocyte differentiation, which required suppression of the expression of the gene encoding the transcription factor FoxC2. These findings indicate that BSTA is a molecular switch that promotes phosphorylation of Akt1 at Ser⁴⁷³ and reveal an mTORC2-BSTA-Akt1-FoxC2-mediated signaling mechanism that is critical for adipocyte differentiation.

miR-337-3p and its targets STAT3 and RAP1A modulate taxane sensitivity in non-small cell lung cancers

NSCLC (non-small cell lung cancer) often exhibits resistance to paclitaxel treatment. Identifying the elements regulating paclitaxel response will advance efforts to overcome such resistance in NSCLC therapy. Using in vitro approaches, we demonstrated that over-expression of the microRNA miR-337-3p sensitizes NCI-H1155 cells to paclitaxel, and that miR-337-3p mimic has a general effect on paclitaxel response in NSCLC cell lines, which may provide a novel adjuvant strategy to paclitaxel in the treatment of lung cancer. By combining in vitro and in silico approaches, we identified STAT3 and RAP1A as direct targets that mediate the effect of miR-337-3p on paclitaxel sensitivity. Further investigation showed that miR-337-3p mimic also sensitizes cells to docetaxel, another member of the taxane family, and that STAT3 levels are significantly correlated with taxane resistance in lung cancer cell lines, suggesting that endogenous STAT3 expression is a determinant of intrinsic taxane resistance in lung cancer. The identification of a miR-337-3p as a modulator of cellular response to taxanes, and STAT3 and RAP1A as regulatory targets which mediate that response, defines a novel regulatory pathway modulating paclitaxel sensitivity in lung cancer cells, which may provide novel adjuvant strategies along with paclitaxel in the treatment of lung cancer and may also provide biomarkers for predicting paclitaxel response in NSCLC.

Abstract 1711: Expression patterns of the G protein-coupled receptor, GPRC5A, in human malignant pleural mesothelioma

The G protein-coupled receptor family C group 5 member A (hGPRC5A, mGprc5a) was previously shown to function as a lung-specific tumor suppressor gene evidenced by the development of lung adenomas and adenocarcinomas in mice with knockout of the gene. Moreover, we have demonstrated that the immunohistochemical expression of GPRC5A protein was significantly lower in non-small cell lung cancer (NSCLC) resected specimens compared to normal bronchial epithelia from healthy individuals. The latter findings prompted us to examine the expression patterns of GPRC5A in malignant pleural mesothelioma (MPM) because, like NSCLC, this malignancy develops in the thoracic cavity. Analysis of two publicly available MPM microarray datasets revealed that GPRC5A mRNA expression is significantly higher in MPMs compared to matched normal pleura (5.5 fold higher, p=0.002; 6.57 fold higher, p=0.04). GPRC5A immunohistochemical protein expression was semi-quantitatively assessed in formalin-fixed paraffin embedded (FFPE) MPM surgical specimens (n=73) comprised of 41 epitheloid, 14 biphasic and 18 sarcomatoid type MPMs. GPRC5A protein expression was also assessed in a subset of the MPM specimens (n=51) that were reconstructed as high-density spiral tissue microarrays (TMA) developed by J. Fukuoka and colleagues (Sakura-Finetek, Tokyo, Japan) comprised of 35 epitheloid, 9 biphasic and 7 sarcomatoid type MPMs. ANOVA analysis demonstrated significant differences in GPRC5A immunohistochemical expression among MPMs based on the histological subtype (p<10-6) with relative highest expression in the epitheloid tumors (mean, 98.04 ± 54.55; min, 0; max, 200), intermediate expression in biphasic-type tumors (mean, 53.57 ± 38.55; min, 0, max, 140) and lowest expression in sarcomatoid-type MPMs (mean, 24.44 ± 21.48; min, 0; max, 70). The patterns of GPRC5A expression based on histological type of surgical MPM specimens were corroborated using the spiral TMA technology with relative highest expression in the epitheloid tumors lowest expression in sarcomatoid-type MPMs. Importantly, GPRC5A immunohistochemical protein expression was positively significantly correlated between the surgical and spiral TMA specimens (R=0.71, p<10-6). We then sought to examine the association of GPRC5A expression with overall survival in MPM. GPRC5A expression was not associated with overall survival when all histological-type MPMs were included. Interestingly, patients with non-epitheloid type MPMs with relatively higher GPRC5A expression exhibited significantly worse overall survival compared to MPM patients with similar histology and lower expression (p=0.02 of the log-rank test). These findings suggest that GPRC5A may function as an oncogene in MPMs and warrant further studies to probe the function of this receptor in mesotheliomas. Supported by DoD PROSPECT grant W81XWH-07-1-0306.

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 1711. doi:1538-7445.AM2012-1711

Abstract 821: Developing a molecular understanding of non small cell lung cancer (NSCLC) resistance to platin-taxane chemotherapy

Purpose: While chemotherapy has improved lung cancer patient survival, relapse rates after neoadjuvant or adjuvant chemotherapy (minimal residual disease settings) are high. This could be due to cancer cells acquiring resistance to therapy or selective survival of pre-existing resistant cells. The molecular basis for primary or acquired resistance to standard platinum doublet chemotherapies are unknown and their elucidation is necessary for developing curative therapy that can be personalized for each patient. Methods: 3 complementary approaches were used to explore mechanisms underlying NSCLC resistance to platin-taxane chemotherapy: A) NSCLC lines were exposed in vitro to cycles of paclitaxel + carboplatin to mimic clinical treatment and resistance validated with cell viability and colony formation assays. Genome wide mRNA expression profiles of resistant and parental lines were compared using Illumina arrays and qRT-PCR. B) A large dataset of clinically and molecularly annotated NSCLC tumor specimens obtained after no chemotherapy or neoadjuvant platin-taxane chemotherapy were subjected to mRNA microarray analysis. C) Lung cancer xenografts were treated with chemotherapy in vivo in mice and profiled for mRNA expression. Biostatistical and bioinformatics approaches were used to identify genes that are differentially expressed in resistant cells in these three settings, and their function studied using over-expression or shRNA mediated knockdown. Results: NSCLC lines H1299 and H1355 were treated in vitro with paclitaxel + carboplatin and showed progressive increases in resistance to chemotherapy (after 5 to 15 cycles) ultimately achieving 30 (H1299) or 60 fold (H1355) differences compared to parental cells. In addition, multiple single cell clones also demonstrated chemotherapy resistance. Resistant NSCLC strains were also resistant to platin+docetaxel and platin+pemetrexed combinations. Expression profiles revealed upregulation of ABCB1/MDR1, down regulation of epithelial-specific genes suggesting EMT, differences in expression of epigenetic modulators as well as cancer testis family of GAGE genes and many of these genes had expression correlated with recurrence after neoadjuvant chemotherapy and with poor survival. Resistance was only partially reversed by verapamil indicating that it can be only partly explained by MDR mechanisms. Mechanistic studies of genes identified by these three approaches provide opportunities for overcoming chemotherapy resistance and developing novel therapies for NSCLC. Grant support: UT-Lung SPORE (5 P50 CA70907-11) and DoD PROSPECT (W81XWH-07-1-0306)

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 821. doi:1538-7445.AM2012-821

Abstract 1714: EZH2Hig h and miR-101Lo w expressions are associated with chemoresistance and shorter survival in patients with lung adenocarcinoma who received adjuvant chemotherapy

Background. EZH2 (a histone methyltransferase and part of the polycomb repressive complex-2) has been implicated in neoplastic transformation, tumor progression, and resistance to chemotherapy. Though EZH2 overexpression has been described in non-small cell lung cancer (NSCLC), there have been no functional studies reported. Recently, it has been demonstrated that miR-101 negatively regulates the expression of EZH2. In this study, we investigated the effect of EZH2 and miR-101 expression levels on the outcome of lung adenocarcinoma patients treated with surgery and adjuvant chemotherapy, and analyzed in vitro mechanisms associated with the role in chemoresistance and cell migration of lung adenocarcinoma. Methods. We analyzed EZH2 and miR-101 expression in RNA extracted from 151 lung adenocarcinoma tumors obtained from patients treated with surgery with (n=57) or without (n=94) platinum adjuvant therapy, and compared those data with patients’ overall survival (median follow-up 5.6 years). EZH2 and miR-101 expression levels were tested using Illumina mRNA arrays W6-6 V.3 and Agilent V3 human microRNA, respectively. We knockdown EZH2 expression in adenocarcinoma cell lines using small interfering RNA (siRNA). Cisplatin sensitivity (IC50) was determined by MTS assay. Cell migration was measured using Boyden chamber. Results. We found that, high EZH2 expression (p=0.007) and low miR101 (p=0.01) expression were significantly associated with worse overall survival in lung adenocarcinoma patients who received platinum adjuvant therapy, but not in patients who did not receive such therapy. Similar results (p=0.008) were observed when combined EZH2High/miR-101Low expression was examined. From a panel of 21 adenocarcinoma cell lines with known EZH2 gene/protein expression, we selected 4 cell lines: 2 with high EZH2 (H1993 and HCC1171), and 2 with low EZH2 (HCC461 and HCC193) expression. Knockdown of EZH2 using siRNA reduced cell migration of H1993 and HCC1171 cells (3.7-fold decrease and 1.7-fold, respectively, p<0.05), but not of HCC193 and HCC461 cells. Knockdown of EZH2 significantly decreased (p<0.05) the viability (by MTS assay) of cell lines H1993 and HCC1171 when treated with cisplatin, but not of HCC193 and HCC461 cells. Conclusion. Our in vitro findings suggest that EZH2 overexpression may promote a more malignant phenotype of lung adenocarcinoma, including increased chemoresistance and cell migration capabilities. Expression of EZH2 and miR-101 may represent a predictive marker of worse outcome in lung adenocarcinoma patients treated with surgery and adjuvant platinum chemotherapy. EZH2 is a potential target that regulates the epigenome to overcome drug resistance in lung cancer (Supported in part by grants DoD PROSPECT W81XWH-07-1-0306 and NCI/UT Lung SPORE 5P50CA70907-11, ER, Becas Chile program)

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 1714. doi:1538-7445.AM2012-1714

Nrf2 and Keap1 abnormalities in non-small cell lung carcinoma and association with clinicopathologic features

PURPOSE

To understand the role of nuclear factor erythroid-2-related factor 2 (Nrf2) and Kelch-like ECH-associated protein 1 (Keap1) in non-small cell lung cancer (NSCLC), we studied their expression in a large series of tumors with annotated clinicopathologic data, including response to platinum-based adjuvant chemotherapy.

EXPERIMENTAL DESIGN

We determined the immunohistochemical expression of nuclear Nrf2 and cytoplasmic Keap1 in 304 NSCLCs and its association with patients' clinicopathologic characteristics, and in 89 tumors from patients who received neoadjuvant (n = 26) or adjuvant platinum-based chemotherapy (n = 63). We evaluated NFE2L2 and KEAP1 mutations in 31 tumor specimens.

RESULTS

We detected nuclear Nrf2 expression in 26% of NSCLCs; it was significantly more common in squamous cell carcinomas (38%) than in adenocarcinomas (18%; P < 0.0001). Low or absent Keap1 expression was detected in 56% of NSCLCs; it was significantly more common in adenocarcinomas (62%) than in squamous cell carcinomas (46%; P = 0.0057). In NSCLC, mutations of NFE2L2 and KEAP1 were very uncommon (2 of 29 and 1 of 31 cases, respectively). In multivariate analysis, Nrf2 expression was associated with worse overall survival [P = 0.0139; hazard ratio (HR), 1.75] in NSCLC patients, and low or absent Keap1 expression was associated with worse overall survival (P = 0.0181; HR, 2.09) in squamous cell carcinoma. In univariate analysis, nuclear Nrf2 expression was associated with worse recurrence-free survival in squamous cell carcinoma patients who received adjuvant treatment (P = 0.0410; HR, 3.37).

CONCLUSIONS

Increased expression of Nrf2 and decreased expression of Keap1 are common abnormalities in NSCLC and are associated with a poor outcome. Nuclear expression of Nrf2 in malignant lung cancer cells may play a role in resistance to platinum-based treatment in squamous cell carcinoma.

Oleandrin-mediated inhibition of human tumor cell proliferation: importance of Na,K-ATPase alpha subunits as drug targets

Cardiac glycosides such as oleandrin are known to inhibit the Na,K-ATPase pump, resulting in a consequent increase in calcium influx in heart muscle. Here, we investigated the effect of oleandrin on the growth of human and mouse cancer cells in relation to Na,K-ATPase subunits. Oleandrin treatment resulted in selective inhibition of human cancer cell growth but not rodent cell proliferation, which corresponded to the relative level of Na,K-ATPase alpha3 subunit protein expression. Human pancreatic cancer cell lines were found to differentially express varying levels of alpha3 protein, but rodent cancer cells lacked discernable expression of this Na,K-ATPase isoform. A correlation was observed between the ratio of alpha3 to alpha1 isoforms and the level of oleandrin uptake during inhibition of cell growth and initiation of cell death; the higher the alpha3 expression relative to alpha1 expression, the more sensitive the cell was to treatment with oleandrin. Inhibition of proliferation of Panc-1 cells by oleandrin was significantly reduced when the relative expression of alpha3 was decreased by knocking down the expression of alpha3 isoform with alpha3 siRNA or increasing expression of the alpha1 isoform through transient transfection of alpha1 cDNA to the cells. Our data suggest that the relative lack of alpha3 (relative to alpha1) in rodent and some human tumor cells may explain their unresponsiveness to cardiac glycosides. In conclusion, the relatively higher expression of alpha3 with the limited expression of alpha1 may help predict which human tumors are likely to be responsive to treatment with potent lipid-soluble cardiac glycosides such as oleandrin.

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

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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.

Suppression of prostate tumor cell growth by stromal cell prostaglandin D synthase-derived products

Stromal-epithelial interactions and the bioactive molecules produced by these interactions maintain tissue homeostasis and influence carcinogenesis. Bioactive prostaglandins produced by prostaglandin synthases and secreted by the prostate into seminal plasma are thought to support reproduction, but their endogenous effects on cancer formation remain unresolved. No studies to date have examined prostaglandin enzyme production or prostaglandin metabolism in normal prostate stromal cells. Our results show that lipocalin-type prostaglandin D synthase (L-PGDS) and prostaglandin D2 (PGD2) metabolites produced by normal prostate stromal cells inhibited tumor cell growth through a peroxisome proliferator-activated receptor gamma (PPARgamma)-dependent mechanism. Enzymatic products of stromal cell L-PGDS included high levels of PGD2 and 15-deoxy-delta(12,14)-PGD2 but low levels of 15-deoxy-delta(12,14)-prostaglandin J2. These PGD2 metabolites activated the PPARgamma ligand-binding domain and the peroxisome proliferator response element reporter systems. Thus, growth suppression of PPARgamma-expressing tumor cells by PGD2 metabolites in the prostate microenvironment is likely to be an endogenous mechanism involved in tumor suppression that potentially contributes to the indolence and long latency period of this disease.

Glycogen synthase kinase-3 beta is involved in the phosphorylation and suppression of androgen receptor activity

Kinases can phosphorylate and regulate androgen receptor activity during prostate cancer progression. In particular, we showed that glycogen synthase kinase-3 beta phosphorylates the androgen receptor, thereby inhibiting androgen receptor-driven transcription. Conversely, the glycogen synthase kinase-3 beta inhibitor lithium chloride suppressed the glycogen synthase kinase-3 beta-mediated phosphorylation of the androgen receptor, thereby enabling androgen receptor-driven transcription to occur. The androgen receptor hinge and ligand-binding domains were important for both the phosphorylation and the inhibition of transcriptional activity of the receptor by glycogen synthase kinase-3 beta. Furthermore, androgen receptor phosphorylation was augmented by LY294002, an indirect inhibitor of protein kinase B/Akt that inhibits glycogen synthase kinase-3 beta. We also showed that the mutation of various phosphorylation sites on glycogen synthase kinase-3 beta affected the ability of these mutants to co-distribute with the androgen receptor in the cell nucleus, also that both glycogen synthase kinase-3beta and androgen receptor proteins can be found in cell nuclei of prostate cancer tissue samples. Because glycogen synthase kinase-3 beta activity is suppressed after the enzyme is phosphorylated by protein kinase B/Akt and Akt activity frequently increases during the progression of prostate cancer, nullification of the glycogen synthase kinase-3 beta-mediated suppression of androgen receptor activity by Akt likely contributes to prostate cancer progression.