SRGN-Triggered Aggressive and Immunosuppressive Phenotype in a Subset of TTF-1-Negative Lung Adenocarcinomas

BACKGROUND

About 20% of lung adenocarcinoma (LUAD) is negative for the lineage-specific oncogene Thyroid transcription factor 1 (TTF-1) and exhibits worse clinical outcome with a low frequency of actionable genomic alterations. To identify molecular features associated with TTF-1-negative LUAD, we compared the transcriptomic and proteomic profiles of LUAD cell lines. SRGN, a chondroitin sulfate proteoglycan Serglycin, was identified as a markedly overexpressed gene in TTF-1-negative LUAD. We therefore investigated the roles and regulation of SRGN in TTF-1-negative LUAD.

METHODS

Proteomic and metabolomic analyses of 41 LUAD cell lines were done using mass spectrometry. The function of SRGN was investigated in 3 TTF-1-negative and 4 TTF-1-positive LUAD cell lines and in a syngeneic mouse model (n = 5 to 8 mice per group). Expression of SRGN in was evaluated in 94 and 105 surgically resected LUAD tumor specimens using immunohistochemistry. All statistical tests were two-sided.

RESULTS

SRGN was markedly overexpressed at mRNA and protein levels in TTF-1-negative LUAD cell lines (P < .001 for both mRNA and protein levels). Expression of SRGN in LUAD tumor tissue was associated with poor outcome (hazard ratio = 4.22, 95% confidential interval = 1.12 to 15.86; likelihood ratio test, P = .03), and with higher expression of Programmed cell death 1 ligand 1 (PD-L1) in tumor cells and higher infiltration of Programmed cell death protein 1 (PD-1)-positive lymphocytes. SRGN regulated expression of PD-L1, as well as proinflammatory cytokines including Interleukin-6 (IL-6), Interleukin-8 (IL-8), and C-X-C motif chemokine 1 (CXCL1) in LUAD cell lines, and increased migratory and invasive properties of LUAD cells and fibroblasts, and enhanced angiogenesis. SRGN was induced by DNA de-methylation resulting from Nicotinamide N-methyltransferase (NNMT)-mediated impairment of methionine metabolism.

CONCLUSION

Our findings suggest that SRGN plays a pivotal role in tumor-stromal interaction and reprogramming into an aggressive and immunosuppressive tumor microenvironment in TTF-1-negative LUAD.

Cell-autonomous immune gene expression is repressed in pulmonary neuroendocrine cells and small cell lung cancer

Small cell lung cancer (SCLC) is classified as a high-grade neuroendocrine (NE) tumor, but a subset of SCLC has been termed “variant” due to the loss of NE characteristics. In this study, we computed NE scores for patient-derived SCLC cell lines and xenografts, as well as human tumors. We aligned NE properties with transcription factor-defined molecular subtypes. Then we investigated the different immune phenotypes associated with high and low NE scores. We found repression of immune response genes as a shared feature between classic SCLC and pulmonary neuroendocrine cells of the healthy lung. With loss of NE fate, variant SCLC tumors regain cell-autonomous immune gene expression and exhibit higher tumor-immune interactions. Pan-cancer analysis revealed this NE lineage-specific immune phenotype in other cancers. Additionally, we observed MHC I re-expression in SCLC upon development of chemoresistance. These findings may help guide the design of treatment regimens in SCLC.

Ling Cai et al. used transcriptomic profiling data of healthy lung, patient-derived small cell lung cancer cell lines, xenografts, and primary tumors to examine a link between neuroendocrine (NE) signatures and immune gene expression. Their findings suggest that cell-autonomous immune gene repression is a shared feature between healthy and tumor cells of NE lineage and may influence tumor-immune cell interaction and response to immunotherapy.

Guanosine triphosphate links MYC-dependent metabolic and ribosome programs in small-cell lung cancer

MYC stimulates both metabolism and protein synthesis, but how cells coordinate these complementary programs is unknown. Previous work reported that, in a subset of small-cell lung cancer (SCLC) cell lines, MYC activates guanosine triphosphate (GTP) synthesis and results in sensitivity to inhibitors of the GTP synthesis enzyme inosine monophosphate dehydrogenase (IMPDH). Here, we demonstrated that primary MYChi human SCLC tumors also contained abundant guanosine nucleotides. We also found that elevated MYC in SCLCs with acquired chemoresistance rendered these otherwise recalcitrant tumors dependent on IMPDH. Unexpectedly, our data indicated that IMPDH linked the metabolic and protein synthesis outputs of oncogenic MYC. Coexpression analysis placed IMPDH within the MYC-driven ribosome program, and GTP depletion prevented RNA polymerase I (Pol I) from localizing to ribosomal DNA. Furthermore, the GTPases GPN1 and GPN3 were upregulated by MYC and directed Pol I to ribosomal DNA. Constitutively GTP-bound GPN1/3 mutants mitigated the effect of GTP depletion on Pol I, protecting chemoresistant SCLC cells from IMPDH inhibition. GTP therefore functioned as a metabolic gate tethering MYC-dependent ribosome biogenesis to nucleotide sufficiency through GPN1 and GPN3. IMPDH dependence is a targetable vulnerability in chemoresistant MYChi SCLC.

A biobank of small cell lung cancer CDX models elucidates inter- and intratumoral phenotypic heterogeneity

Although small cell lung cancer (SCLC) is treated as a homogeneous disease, biopsies and preclinical models reveal heterogeneity in transcriptomes and morphology. SCLC subtypes were recently defined by neuroendocrine transcription factor (NETF) expression. Circulating-tumor-cell-derived explant models (CDX) recapitulate donor patients' tumor morphology, diagnostic NE marker expression and chemotherapy responses. We describe a biobank of 38 CDX models, including six CDX pairs generated pretreatment and at disease progression revealing complex intra- and intertumoral heterogeneity. Transcriptomic analysis confirmed three of four previously described subtypes based on ASCL1, NEUROD1 and POU2F3 expression and identified a previously unreported subtype based on another NETF, ATOH1. We document evolution during disease progression exemplified by altered MYC and NOTCH gene expression, increased 'variant' cell morphology, and metastasis without strong evidence of epithelial to mesenchymal transition. This CDX biobank provides a research resource to facilitate SCLC personalized medicine.

Author Correction: Molecular subtypes of small cell lung cancer: a synthesis of human and mouse model data

An amendment to this paper has been published and can be accessed via a link at the top of the paper.

ClickGene: an open cloud-based platform for big pan-cancer data genome-wide association study, visualization and exploration

Tremendous amount of whole-genome sequencing data have been provided by large consortium projects such as TCGA (The Cancer Genome Atlas), COSMIC and so on, which creates incredible opportunities for functional gene research and cancer associated mechanism uncovering. While the existing web servers are valuable and widely used, many whole genome analysis functions urgently needed by experimental biologists are still not adequately addressed. A cloud-based platform, named CG (ClickGene), therefore, was developed for DIY analyzing of user's private in-house data or public genome data without any requirement of software installation or system configuration. CG platform provides key interactive and customized functions including Bee-swarm plot, linear regression analyses, Mountain plot, Directional Manhattan plot, Deflection plot and Volcano plot. Using these tools, global profiling or individual gene distributions for expression and copy number variation (CNV) analyses can be generated by only mouse button clicking. The easy accessibility of such comprehensive pan-cancer genome analysis greatly facilitates data mining in wide research areas, such as therapeutic discovery process. Therefore, it fills in the gaps between big cancer genomics data and the delivery of integrated knowledge to end-users, thus helping unleash the value of the current data resources. More importantly, unlike other R-based web platforms, Dubbo, a cloud distributed service governance framework for 'big data' stream global transferring, was used to develop CG platform. After being developed, CG is run on an independent cloud-server, which ensures its steady global accessibility. More than 2 years running history of CG proved that advanced plots for hundreds of whole-genome data can be created through it within seconds by end-users anytime and anywhere. CG is available at http://www.clickgenome.org/.

Comparison of four DLL3 antibodies performance in high grade neuroendocrine lung tumor samples and cell cultures

Background

Small cell lung cancer (SCLC) is usually diagnosed in the advanced stage. It has a very poor prognosis, with no advancements in therapy in the last few decades. A recent phase 1 clinical study, using an antibody-drug conjugate directed against DLL3, showed promising results. A prerequisite for this therapy is an immunohistochemical test for DLL3 expression. The antibody used in the clinical trial was bound to a specific platform, which is not available in all pathology laboratories. In this study, the expression of DLL3 was analyzed using different DLL3 antibodies in high-grade neuroendocrine tumors of the lung and cell cultures. Additionally, correlation of DLL3 expression with Rb1 loss and TP53 mutation was evaluated.

Methods

The study cohort consisted of surgically resected cases, 24 SCLC and 29 large cell neuroendocrine carcinoma (LCNEC), from which tissue microarrays (TMAs) were constructed. The validation cohort included 46 SCLC samples, mostly small biopsies. Additionally, well-characterized SCLC cell lines were used. Immunohistochemical analysis was performed using four different DLL3 antibodies, as well as TP53 and Rb1 antibodies. Expression was evaluated microscopically and manually scored.

Results

The comparison of all DLL3 antibodies showed poor results for the overall agreement, as well as positive and negative agreement. Differences were observed regardless of the applied cut-off values and the tumor type. The antibody used in the clinical trial was the only which always positively stained the tumor cells obtained from cell cultures with known DLL3 expression and was negative on cells that did not express DLL3. There was no correlation between p53 and DLL3 expression in SCLC and LCNEC. RB1 loss in SCLC showed statistical significant correlation with the DLL3 positivity (p = 0.037), while no correlation was found in LCNEC.

Conclusion

The DLL3 antibody used in the clinical trial demonstrated superiority in the detection of DLL3 expression. Cell cultures, which can be used for DLL3 antibodies as positive and negative probes, were established. Evidence of DLL3 expression in high proportions of patients with LCNEC might provide basis for studies of new therapy options in this group of patients.

Molecular subtypes of small cell lung cancer: a synthesis of human and mouse model data

Small cell lung cancer (SCLC) is an exceptionally lethal malignancy for which more effective therapies are urgently needed. Several lines of evidence, from SCLC primary human tumours, patient-derived xenografts, cancer cell lines and genetically engineered mouse models, appear to be converging on a new model of SCLC subtypes defined by differential expression of four key transcription regulators: achaete-scute homologue 1 (ASCL1; also known as ASH1), neurogenic differentiation factor 1 (NeuroD1), yes-associated protein 1 (YAP1) and POU class 2 homeobox 3 (POU2F3). In this Perspectives article, we review and synthesize these recent lines of evidence and propose a working nomenclature for SCLC subtypes defined by relative expression of these four factors. Defining the unique therapeutic vulnerabilities of these subtypes of SCLC should help to focus and accelerate therapeutic research, leading to rationally targeted approaches that may ultimately improve clinical outcomes for patients with this disease.

Small cell lung cancers made from scratch

A new approach to modeling human small cell lung cancer (SCLC) by transforming human ESCs.

In this issue of JEM, Chen et al. (https://doi.org/10.1084/jem.20181155) describe a new approach for the transformation of human pluripotent embryonic stem cells (hESCs) into neuroendocrine (NE) tumors of the lung closely resembling human small cell lung cancer (SCLC). Another recent study uses a different method to transform fully differentiated normal human cells into high-grade NE tumors (Park et al. 2018. Science. https://doi.org/10.1126/science.aat5749). These approaches and their models provide important new resources for developing diagnostic, preventative, and therapeutic approaches for high-grade NE tumors.

Crebbp Loss Drives Small Cell Lung Cancer and Increases Sensitivity to HDAC Inhibition

CREBBP, encoding an acetyltransferase, is among the most frequently mutated genes in small cell lung cancer (SCLC), a deadly neuroendocrine tumor type. We report acceleration of SCLC upon Crebbp inactivation in an autochthonous mouse model. Extending these observations beyond the lung, broad Crebbp deletion in mouse neuroendocrine cells cooperated with Rb1/Trp53 loss to promote neuroendocrine thyroid and pituitary carcinomas. Gene expression analyses showed that Crebbp loss results in reduced expression of tight junction and cell adhesion genes, including Cdh1, across neuroendocrine tumor types, whereas suppression of Cdh1 promoted transformation in SCLC. CDH1 and other adhesion genes exhibited reduced histone acetylation with Crebbp inactivation. Treatment with the histone deacetylase (HDAC) inhibitor Pracinostat increased histone acetylation and restored CDH1 expression. In addition, a subset of Rb1/Trp53/Crebbp-deficient SCLC exhibited exceptional responses to Pracinostat in vivo Thus, CREBBP acts as a potent tumor suppressor in SCLC, and inactivation of CREBBP enhances responses to a targeted therapy.Significance: Our findings demonstrate that CREBBP loss in SCLC reduces histone acetylation and transcription of cellular adhesion genes, while driving tumorigenesis. These effects can be partially restored by HDAC inhibition, which exhibited enhanced effectiveness in Crebbp-deleted tumors. These data provide a rationale for selectively treating CREBBP-mutant SCLC with HDAC inhibitors. Cancer Discov; 8(11); 1422-37. ©2018 AACR. This article is highlighted in the In This Issue feature, p. 1333.

Abstract B09: Evaluating transcription factor networks as targets for the treatment of small cell lung cancer

Achaete-scute homolog 1 (ASCL1) is a transcription factor that is highly expressed in most small cell lung cancer (SCLC) tumors and cell lines and is critical for their proliferation. Inhibiting ASCL1 transcriptional activity may thus be a valid therapeutic strategy for SCLC. However, transcription factors (TFs) have been historically difficult to target. Given that TFs belong to complex regulatory networks, we propose to identify and target multiple components within an ASCL1-transcriptional network rather than ASCL1 alone. We have previously detected ASCL1-bound genomic regions associated with the active chromatin epigenetic mark, H3K27Ac in SCLC cells. Here we report the identification of an ASCL1-containing transcriptional network in SCLC cells and evaluate its targeting by the transcriptional inhibitor, mithramycin. We conducted chromatin immunoprecipitation (ChIP) by immunoprecipitating the H3K27Ac chromatin mark from NCI-H2107 and NCI-H69 SCLCs (5X107 cells) nuclear lysates with10 μg H3K27Ac antibodies (Abcam-Ab4729), and sequenced ChIP libraries on an Illumina High-Seq2000. Further characterization using siRNA transfections, immunoblotting and MTS-cell proliferation assays were conducted following standard procedures. We found 82 overlapping TF genes, including lineage-specific TF genes for ASCL1, Forkhead box protein A2 (FOXA2), and nuclear factor 1 B-type (NFIB), associated with the active chromatin epigenetic marks H3K27Ac in SCLC cell lines. This suggests that ASCL1, FOXA2, and NFIB may belong to the same transcriptional network. siRNA-mediated knockdown of ASCL1 leads to decreased FOXA2 levels, but it has no effect on NFIB levels, implicating ASCL1 as a transcriptional regulator of FOXA2 but not NFIB. Mithramycin stops cell proliferation and reduces ASCL1, FOXA2 but not NFIB protein levels. In conclusion, our studies identify the beginning of a transcriptional network necessary for SCLC proliferation in which ASCL1 regulates FOXA2. Targeting multiple TFs within a network with mithramycin can stop cell proliferation and as such suggests a therapeutic strategy for SCLC. Because of the importance of NFIB in mediating metastatic behavior of SCLC, these data indicate that approaches other than targeting ASCL1 and use of mithramycin will be needed to target NFIB.

Citation Format: Karine Pozo, Rahul K. Kollipara, John D. Minna, Adi F. Gazdar, Jane E. Johnson. Evaluating transcription factor networks as targets for the treatment of small cell lung cancer [abstract]. In: Proceedings of the Fifth AACR-IASLC International Joint Conference: Lung Cancer Translational Science from the Bench to the Clinic; Jan 8-11, 2018; San Diego, CA. Philadelphia (PA): AACR; Clin Cancer Res 2018;24(17_Suppl):Abstract nr B09.

Abstract IA27: MYC drives molecular and therapeutically distinct subtype of SCLC

Small cell lung cancer (SCLC) has largely been treated in the clinic as a homogeneous disease for the last 40 years. However, it is become increasingly appreciated that SCLC exhibits both intra- and intertumoral heterogeneity. Genetic loss of the tumor suppressors RB1 and TP53 is nearly universal in SCLC, while amplifications in MYC family members including C-, L-, and N-MYC are mutually exclusive. Using genetically engineered mouse models (GEMMs), we show that MycT58A expression cooperates with Rb1 and Trp53 loss in the mouse lung to promote aggressive, highly metastatic tumors that are initially sensitive to chemotherapy followed by relapse, similar to human SCLC. Importantly, MYC drives a neuroendocrine-low ‘‘variant’’ subset of SCLC with low ASCL1 and high NEUROD1 expression corresponding to transcriptional profiles of human SCLC. The MYC-driven subset of SCLC is also low for other clinically relevant biomarkers such as TTF1/NKX2.1 and DLL3. Targeted drug screening reveals that SCLC with high MYC expression is vulnerable to Aurora kinase inhibition, which, combined with chemotherapy, strongly suppresses tumor progression and increases survival. These findings are consistent with the results of recent clinical trials in patients with relapsed SCLC who received paclitaxel with or without the AURKA inhibitor alisertib. Furthermore, recent preclinical studies demonstrate that the MYC-driven subset of SCLC is preferentially sensitive to CHK1 inhibition and other metabolic targets compared to MYCL-driven SCLC. These data identify molecular features for patient stratification and uncover potential targeted treatment approaches for MYC-driven SCLC.

Citation Format: Gurkan Mollaoglu, Matthew R. Guthrie, Stefanie Bohm, Johannes Bragelmann, Milind D. Chalishazar, Abbie S. Ireland, Fang Huang, Zeping Hu, Robert J. Cardnell, Triparna Sen, Jason Gertz, Jane E. Johnson, Adi F. Gazdar, Lauren A. Byers, Ralph J. DeBerardinis, Robert J. Wechsler-Reya, Martin Sos, Trudy G. Oliver. MYC drives molecular and therapeutically distinct subtype of SCLC [abstract]. In: Proceedings of the Fifth AACR-IASLC International Joint Conference: Lung Cancer Translational Science from the Bench to the Clinic; Jan 8-11, 2018; San Diego, CA. Philadelphia (PA): AACR; Clin Cancer Res 2018;24(17_Suppl):Abstract nr IA27.

A quantitative method for assessing smoke associated molecular damage in lung cancers

BACKGROUND

While tobacco exposure is the cause of the vast majority of lung cancers, an important percentage arise in lifetime never smokers. Documenting the precise extent of tobacco induced molecular changes may be of importance. Also, the contribution of environmental tobacco smoke (ETS) is difficult to assess.

METHODS

We developed and validated a quantitative method to assess the extent of tobacco related molecular damage by combing the most characteristic changes associated with tobacco smoke, the tumor mutation burden (TMB) and type of molecular changes present in lung cancers. Using maximum entropy (MaxEnt) as a classifier, we developed a F score. F score values >0 were considered to show evidence of tobacco related molecular damage, while values ≤0 were considered to lack evidence of tobacco related molecular damage. Compared to the stated patient tobacco exposure histories, the F scores had sensitivity, specificity and accuracy values of 85-87%. Using this method, we analyzed public data sets of lung adenocarcinoma (LUAD), lung squamous cell (LUSC) and small cell lung cancer (SCLC).

RESULTS

Less than 10% of LUSCs and SCLCs had negative F scores, while 27% to 35% of LUADs had positive scores. The F score showed a highly significant downward trend when LUADs were subdivided into the following categories: ever, reformed ≤15 years, reformed >15 years and never smokers. Most of the examined bronchial carcinoids (a lung cancer type not associated with smoke exposure) had negative F scores. In addition, most LUADs with EGFR mutations had negative F scores, while almost all with KRAS mutations had positive scores.

CONCLUSIONS

We have established and validated a quantitative assay that will be of use in assessing the presence and degree of smoke associated molecular damage in lung cancers arising in ever and never smokers.

Elements of the rabbit uteroglobin promoter mediating its transcription in epithelial cells from the endometrium and lung

The rabbit uteroglobin gene is specifically expressed in certain epithelial cells of ontogenetically unrelated origin. In the endometrium, expression is restricted to the glandular and luminal epithelium and is inducible by progesterone and estradiol. In the lung, Clara cells lining the bronchiolar epithelium show constitutive expression of uteroglobin, which is modulated by glucocorticoids. To explore the molecular basis for this cell type specificity, we have transiently transfected the uteroglobin promoter region fused to the chloramphenicol acetyl transferase gene (CAT gene) in the endometrial cell line Ishikawa; in the human lung cell line NCI-H441, which shows morphological Clara cell characteristics; in HeLa cells; and in three fibroblast cell lines. The uteroglobin promoter efficiently drives expression of the CAT gene in Ishikawa and NCI-H441 cells, but not in HeLa and fibroblast cells. To identify the responsible elements we have analyzed progressive promoter 5'-deletion mutants and randomly generated linker scanning mutants spanning the sequence from -258 to -14 of the uteroglobin promoter. Transfection experiments reveal seven mutation-sensitive regions located around -30, -70, -95, -130, -190, -230, and -255. Several mutants display strong cell type-specific phenotypes. Most significantly, the integrity of the region around -190 is essential for full CAT gene expression in Ishikawa cells, but not in NCI-H441 cells.

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.

Dysregulation of fibulin-5 and matrix metalloproteases in epithelial ovarian cancer

Fibulin 5 (FBLN5) is an extracellular matrix glycoprotein that suppresses matrix metalloprotease 9 (MMP-9), angiogenesis and epithelial cell motility. Here, we investigated the regulation and function of FBLN5 in epithelial ovarian cancer (EOC). FBLN5 mRNA was down-regulated 5-fold in EOC relative to benign ovary. Not surprisingly, MMP9 mRNA and enzyme activity were increased significantly, and inversely correlated with FBLN5 gene expression. FBLN5 degradation products of 52.8 and 41.3 kDa were increased substantially in EOC. We identified two candidate proteases (serine elastase and MMP-7, but not MMP-9) that cleave FBLN5. MMP-7, but not neutrophil elastase, gene expression was increased dramatically in EOC. Recombinant FBLN5 significantly inhibited adhesion of EOC cells to both laminin and collagen I. Finally, using immunohistochemistry, we found immunoreactive FBLN5 within tumor macrophages throughout human EOC tumors. This work indicates that FBLN5 is degraded in EOC most likely by proteases enriched in macrophages of the tumor microenvironment. Proteolysis of FBLN5 serves as a mechanism to promote cell adhesion and local metastasis of ovarian cancer cells. Promotion of a stable ECM with intact FBLN5 in the tumor matrix may serve as a novel therapeutic adjunct to prevent spread of ovarian cancer.

The Epithelial Sodium Channel (αENaC) Is a Downstream Therapeutic Target of ASCL1 in Pulmonary Neuroendocrine Tumors

Small cell lung cancer (SCLC) is an aggressive neuroendocrine carcinoma, designated as a recalcitrant cancer by the National Cancer Institute, in urgent need of new rational therapeutic targets. Previous studies have determined that the basic helix-loop-helix transcription factor achaete-scute homolog 1 (ASCL1) is essential for the survival and progression of a fraction of pulmonary neuroendocrine cancer cells, which include both SCLC and a subset of non-SCLC. Previously, to understand how ASCL1 initiates tumorigenesis in pulmonary neuroendocrine cancer and identify the transcriptional targets of ASCL1, whole-genome RNA-sequencing analysis combined with chromatin immunoprecipitation-sequencing was performed with a series of lung cancer cell lines. From this analysis, we discovered that the gene SCNN1A, which encodes the alpha subunit of the epithelial sodium channel (αENaC), is highly correlated with ASCL1 expression in SCLC. The product of the SCNN1A gene ENaC can be pharmacologically inhibited with amiloride, a drug that has been used clinically for close to 50 years. Amiloride inhibited growth of ASCL1-dependent SCLC more strongly than ASCL1-independent SCLC in vitro and slowed growth of ASCL1-driven SCLC in xenografts. We conclude that SCNN1A/αENaC is a direct transcriptional target of the neuroendocrine lung cancer lineage oncogene ASCL1 that can be pharmacologically targeted with antitumor effects.

Small cell lung cancer tumors and preclinical models display heterogeneity of neuroendocrine phenotypes

Background

Small cell lung cancer (SCLC) is a deadly, high grade neuroendocrine (NE) tumor without recognized morphologic heterogeneity. However, over 30 years ago we described a SCLC subtype with "variant" morphology which did not express some NE markers and exhibited more aggressive growth.

Methods

To quantitate NE properties of SCLCs, we developed a 50-gene expression-based NE score that could be applied to human SCLC tumors and cell lines, and genetically engineered mouse (GEM) models. We identified high and low NE subtypes of SCLC in all of our sample types, and characterized their properties.

Results

We found that 16% of human SCLC tumors and 10% of SCLC cell lines were of the low NE subtype, as well as cell lines from the GEM model. High NE SCLC lines grew as non-adherent floating aggregates or spheroids while Low NE lines had morphologic features of the variant subtype and grew as loosely attached cells. While the high NE subtype expressed one of the NE lineage master transcription factors ASCL1 or NEUROD1, together with NKX2-1, the entire range of NE markers, and lacked expression of the neuronal and NE repressor REST, the low NE subtype had lost expression of most NE markers, ASCL1, NEUROD1 and NKX2-1 and expressed REST. The low NE subtype had undergone epithelial mesenchymal transition (EMT) and had activated the Notch, Hippo and TGFβ pathways and MYC oncogene . Importantly, the high and low NE group of SCLC lines had similar gene expression profiles as their SCLC tumor counterparts.

Conclusions

SCLC tumors and cell lines can exhibit distinct inter-tumor heterogeneity with respect to expression of NE features. Loss of NE expression results in major alterations in morphology, growth characteristics, and molecular properties. These findings have major clinical implications as the two subtypes are predicted to have very different responses to targeted therapies.

Telomerase inhibitor imetelstat has preclinical activity across the spectrum of non-small cell lung cancer oncogenotypes in a telomere length dependent manner

Telomerase was evaluated as a therapeutic oncotarget by studying the efficacy of the telomerase inhibitor imetelstat in non-small cell lung cancer (NSCLC) cell lines to determine the range of response phenotypes and identify potential biomarkers of response. A panel of 63 NSCLC cell lines was studied for telomere length and imetelstat efficacy in inhibiting colony formation and no correlation was found with patient characteristics, tumor histology, and oncogenotypes. While there was no overall correlation between imetelstat efficacy with initial telomere length (ranging from 1.5 to 20 kb), the quartile of NSCLC lines with the shortest telomeres was more sensitive than the quartile with the longest telomeres. Continuous long-term treatment with imetelstat resulted in sustained telomerase inhibition, progressive telomere shortening and eventual growth inhibition in a telomere-length dependent manner. Cessation of imetelstat therapy before growth inhibition was followed by telomere regrowth. Likewise, in vivo imetelstat treatment caused tumor xenograft growth inhibition in a telomere-length dependent manner. We conclude from these preclinical studies of telomerase as an oncotarget tested by imetelstat response that imetelstat has efficacy across the entire oncogenotype spectrum of NSCLC, continuous therapy is necessary to prevent telomere regrowth, and short telomeres appears to be the best treatment biomarker.

Small-cell lung cancer: what we know, what we need to know and the path forward

Small-cell lung cancer (SCLC) is a deadly tumour accounting for approximately 15% of lung cancers and is pathologically, molecularly, biologically and clinically very different from other lung cancers. While the majority of tumours express a neuroendocrine programme (integrating neural and endocrine properties), an important subset of tumours have low or absent expression of this programme. The probable initiating molecular events are inactivation of TP53 and RB1, as well as frequent disruption of several signalling networks, including Notch signalling. SCLC, when diagnosed, is usually widely metastatic and initially responds to cytotoxic therapy but nearly always rapidly relapses with resistance to further therapies. There were no important therapeutic clinical advances for 30 years, leading SCLC to be designated a 'recalcitrant cancer'. Scientific studies are hampered by a lack of tissue availability. However, over the past 5 years, there has been a worldwide resurgence of studies on SCLC, including comprehensive molecular analyses, the development of relevant genetically engineered mouse models and the establishment of patient-derived xenografts. These studies have led to the discovery of new potential therapeutic vulnerabilities for SCLC and therefore to new clinical trials. Thus, while the past has been bleak, the future offers greater promise.

Small-cell lung cancer: what we know, what we need to know and the path forward

This corrects the article DOI: 10.1038/nrc.2017.87.

Role of CPS1 in Cell Growth, Metabolism and Prognosis in LKB1-Inactivated Lung Adenocarcinoma

Background

Liver kinase B1 ( LKB1 ) is a tumor suppressor in lung adenocarcinoma (LADC). We investigated the proteomic profiles of 45 LADC cell lines with and without LKB1 inactivation. Carbamoyl phosphate synthetase 1 (CPS1), the first rate-limiting mitochondrial enzyme in the urea cycle, was distinctively overexpressed in LKB1-inactivated LADC cell lines. We therefore assessed the role of CPS1 and its clinical relevance in LKB1-inactivated LADC.

Methods

Mass spectrometric profiling of proteome and metabolome and function of CPS1 were analyzed in LADC cell lines. CPS1 and LKB1 expression in tumors from 305 LADC and 160 lung squamous cell carcinoma patients was evaluated by immunohistochemistry. Kaplan-Meier and Cox regression analyses were applied to assess the association between overall survival and CPS1 and LKB1 expression. All statistical tests were two-sided.

Results

CPS1 knockdown reduced cell growth, decreased metabolite levels associated with nucleic acid biosynthesis pathway, and contributed an additive effect when combined with gemcitabine, pemetrexed, or CHK1 inhibitor AZD7762. Tissue microarray analysis revealed that CPS1 was expressed in 65.7% of LKB1-negative LADC, and only 5.0% of LKB1-positive LADC. CPS1 expression showed statistically significant association with poor overall survival in LADC (hazard ratio = 3.03, 95% confidence interval = 1.74 to 5.25, P < .001).

Conclusions

Our findings suggest functional relevance of CPS1 in LKB1-inactivated LADC and association with worse outcome of LADC. CPS1 is a promising therapeutic target in combination with other chemotherapy agents, as well as a prognostic biomarker, enabling a personalized approach to treatment of LADC.

Abstract 2775: CPS1 as a therapeutic target and prognostic indicator in LKB1-inactivated lung adenocarcinoma

Liver Kinase B1 (LKB1), encoded by STK11, is a tumor suppressor and somatically mutated in approximately 20% of lung adenocarcinoma. Aside from the effects of LKB1 inactivation on tumor initiation, LKB1-mutant cancers are biologically distinct from cancer with functional LKB1, and the loss of LKB1 uniquely confers invasive and metastatic properties in genetically engineered mouse models of cancer. While various pathways, including energy metabolism, cell polarity, and cell growth, are regulated by LKB1 and can play a pleiotropic role in cancer initiation and progression, no therapies are currently available for clinical use that specifically target LKB1 inactivation. Therefore, elucidation of the functional mechanisms associated with LKB1 inactivation has translational relevance.

We analyzed proteomic profiles of 45 lung adenocarcinoma cell lines with and without LKB1 inactivation to identify molecular features associated with LKB1 inactivation. Carbamoyl phosphate synthase 1 (CPS1) was identified as a markedly overexpressed protein in LKB1-inactivated lung adenocarcinoma cell lines. CPS1 is the first rate-limiting mitochondrial enzyme in the urea cycle, and plays an intricate role in arginine and pyrimidine metabolism. CPS1 knockdown reduced cell growth, decreased levels of metabolites associated with nucleic acid biosynthesis pathway, and contributed an additive effect when combined with conventional chemotherapy agents including gemcitabine, pemetrexed, or CHK1 inhibitor AZD7762. Tissue microarray analysis using 305 lung adenocarcinoma tumors revealed that CPS1 was expressed in 65.7% of LKB1-negative and only 5.0% of LKB1-positive lung adenocarcinomas. In addition, CPS1 expression was significantly and independently associated with poor overall survival of lung adenocarcinoma patients (P &lt; 0.0001, HR = 3.03, 95% CI 1.74-5.25). Concordant with the results of tissue microarray, analysis of the Cancer Genome Atlas (TCGA) dataset consisting 403 lung adenocarcinomas revealed that high CPS1 mRNA expression was significantly associated with worse overall survival and is an independent prognostic indicator of lung adenocarcinoma (P = 0.005, HR = 2.31, 95% CI 1.28-4.16). Our findings suggest functional relevance of CPS1 and its association with worse outcome in LKB1-inactivated lung adenocarcinoma. Therefore, CPS1 is a promising therapeutic target in combination with other chemotherapy agents, as well as a prognostic biomarker, enabling us to personalize the treatment of LKB1-inactivated lung adenocarcinoma.

Citation Format: Muge Celiktas, Ichidai Tanaka, Satyendra Chandra Tripathi, Johannes F. Fahrmann, Clemente Aguilar-Bonavides, Pamela Villalobos, Oliver Delgado, Dilsher Dhillon, Jennifer B. Dennison, Edwin J. Ostrin, Hong Wang, Carmen Behrens, Kim-Anh Do, Adi F. Gazdar, Samir M. Hanash, Ayumu Taguchi. CPS1 as a therapeutic target and prognostic indicator in LKB1-inactivated lung adenocarcinoma [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 2775. doi:10.1158/1538-7445.AM2017-2775

Abstract 5715: Gene body methylation and expression of SHOX2 gene are potent prognostic markers for survival in intermediate grade gliomas and renal cancers

Background: Previous data indicated that low level of promoter methylation of the SHOX2 gene was a prognostic marker for worse progression-free survival for non-small cell lung cancer.

Purpose: (a) to determine the relationship between SHOX2 gene methylation and expression; b) to determine whether SHOX2 gene methylation and expression were prognostic markers for other cancers.

Methods: We examined multiple methylation and expression datasets available from The Cancer Genome Atlas (TCGA) and other previously published studies. Data from a total of more than 1000 intermediate grade gliomas and 1100 renal cancer cases were examined, along with smaller number of corresponding non-malignant tissues. We performed Kaplan-Meier survival analyses and univariate and multivariate Cox regression model analyses.

Results: SHOX2 gene contains three CpG islands encompassing the promoter region and body. Methylation of various regions of SHOX2 gene body was significantly positively correlated with its expression in gliomas and renal cancer. Aberrantly high methylation and expression of SHOX2 gene, which were significantly higher than the corresponding nonmalignant tissues, were identified in subsets of gliomas and renal cancers. Survival analysis of patients indicated that the methylation and expression of SHOX2 gene in gliomas and renal cancer (both clear cell and papillary cell carcinomas) were highly potent markers for poor survival. We further investigated the combination of SHOX2 with other known clinically relevant glioma markers (IDH genotype status, TERT expression, 1p/19q chromosome co-deletion, MGMT methylation, ATRX mutation and NES expression). When combined with SHOX2 expression, we identified subsets of glioma patients with significantly favorable survival outcomes, especially in the subgroup (i.e., IDH wild-type) associated with worse prognosis for each individual marker. Multivariate analysis demonstrated that SHOX2 was a potent independent survival marker for gliomas.

Conclusion: Gene body methylation and expression of SHOX2 gene are tightly positively correlated and are potent new markers for overall survival prognosis for intermediate grade gliomas and renal cancer. The combination of IDH or other relevant prognostic markers with SHOX2 identified intermediate grade glioma subsets with improved survival outcomes.

Citation Format: Yu-An Zhang, Yunyun Zhou, Xin Luo, Guanghua Xiao, Adi F. Gazdar. Gene body methylation and expression of SHOX2 gene are potent prognostic markers for survival in intermediate grade gliomas and renal cancers [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 5715. doi:10.1158/1538-7445.AM2017-5715

GLI1 Blockade Potentiates the Antitumor Activity of PI3K Antagonists in Lung Squamous Cell Carcinoma

Lung squamous cell carcinoma (SCC), strongly associated with smoking, is treated primarily with traditional cytotoxic chemotherapy due to a lack of FDA-approved targeted agents available. Here, we identify the Hedgehog pathway transcription factor GLI1 as a critical driver of lung SCC. Analysis of human lung cancer datasets showed that GLI1 mRNA was highly expressed in human lung SCC and portended a poor prognosis. Inhibition of GLI1 in human lung SCC cell lines suppressed tumor cell clonogenicity and proliferation in culture and in vivo Addition of SHH ligand, SMO antagonists, or other Hedgehog pathway agonists did not affect GLI1 expression in lung SCC cells. However, GLI1 expression was modulated by either inhibition or activation of the PI3K and MAPK pathways. Furthermore, in vivo growth of SCC harboring amplifications of the PI3K gene PIK3CA was attenuated by antagonizing GLI1 and PI3K. Thus, a combinatorial therapeutic strategy that targets the PI3K-mTOR pathway and GLI1 may lead to effective outcomes for PI3K pathway-dependent cancers, in contrast to recent results of human trials with single-agent PI3K antagonists. Cancer Res; 77(16); 4448-59. ©2017 AACR.

Genome-wide copy number variation pattern analysis and a classification signature for non-small cell lung cancer

The accurate classification of non-small cell lung carcinoma (NSCLC) into lung adenocarcinoma (LUAD) and lung squamous cell carcinoma (LUSC) is essential for both clinical practice and lung cancer research. Although the standard WHO diagnosis of NSCLC on biopsy material is rapid and economic, more than 13% of NSCLC tumors in the USA are not further classified. The purpose of this study was to analyze the genome-wide pattern differences in copy number variations (CNVs) and to develop a CNV signature as an adjunct test for the routine histopathologic classification of NSCLCs. We investigated the genome-wide CNV differences between these two tumor types using three independent patient datasets. Approximately half of the genes examined exhibited significant differences between LUAD and LUSC tumors and the corresponding non-malignant tissues. A new classifier was developed to identify signature genes out of 20 000 genes. Thirty-three genes were identified as a CNV signature of NSCLC. Using only their CNV values, the classification model separated the LUADs from the LUSCs with an accuracy of 0.88 and 0.84, respectively, in the training and validation datasets. The same signature also classified NSCLC tumors from their corresponding non-malignant samples with an accuracy of 0.96 and 0.98, respectively. We also compared the CNV patterns of NSCLC tumors with those of histologically similar tumors arising at other sites, such as the breast, head, and neck, and four additional tumors. Of greater importance, the significant differences between these tumors may offer the possibility of identifying the origin of tumors whose origin is unknown.

Genetic requirement for Mycl and efficacy of RNA Pol I inhibition in mouse models of small cell lung cancer

Kim et al. isolated preneoplastic neuroendocrine cells from a mouse model of small cell lung cancer (SCLC) and found that ectopic expression of L-Myc conferred tumor-forming capacity. An RNA polymerase I inhibitor used to target rRNA synthesis resulted in significant tumor inhibition in an autochthonous Rb/p53-deleted mouse SCLC model.

Small cell lung cancer (SCLC) is a devastating neuroendocrine carcinoma. MYCL (L-Myc) is frequently amplified in human SCLC, but its roles in SCLC progression are poorly understood. We isolated preneoplastic neuroendocrine cells from a mouse model of SCLC and found that ectopic expression of L-Myc, c-Myc, or N-Myc conferred tumor-forming capacity. We focused on L-Myc, which promoted pre-rRNA synthesis and transcriptional programs associated with ribosomal biogenesis. Deletion of Mycl in two genetically engineered models of SCLC resulted in strong suppression of SCLC. The high degree of suppression suggested that L-Myc may constitute a therapeutic target for a broad subset of SCLC. We then used an RNA polymerase I inhibitor to target rRNA synthesis in an autochthonous Rb/p53-deleted mouse SCLC model and found significant tumor inhibition. These data reveal that activation of RNA polymerase I by L-Myc and other MYC family proteins provides an axis of vulnerability for this recalcitrant cancer.

MYC Drives Progression of Small Cell Lung Cancer to a Variant Neuroendocrine Subtype with Vulnerability to Aurora Kinase Inhibition

Loss of the tumor suppressors RB1 and TP53 and MYC amplification are frequent oncogenic events in small cell lung cancer (SCLC). We show that Myc expression cooperates with Rb1 and Trp53 loss in the mouse lung to promote aggressive, highly metastatic tumors, that are initially sensitive to chemotherapy followed by relapse, similar to human SCLC. Importantly, MYC drives a neuroendocrine-low "variant" subset of SCLC with high NEUROD1 expression corresponding to transcriptional profiles of human SCLC. Targeted drug screening reveals that SCLC with high MYC expression is vulnerable to Aurora kinase inhibition, which, combined with chemotherapy, strongly suppresses tumor progression and increases survival. These data identify molecular features for patient stratification and uncover a potential targeted treatment approach for MYC-driven SCLC.

Characterization of Human Cancer Cell Lines by Reverse-phase Protein Arrays

Cancer cell lines are major model systems for mechanistic investigation and drug development. However, protein expression data linked to high-quality DNA, RNA, and drug-screening data have not been available across a large number of cancer cell lines. Using reverse-phase protein arrays, we measured expression levels of ∼230 key cancer-related proteins in >650 independent cell lines, many of which have publically available genomic, transcriptomic, and drug-screening data. Our dataset recapitulates the effects of mutated pathways on protein expression observed in patient samples, and demonstrates that proteins and particularly phosphoproteins provide information for predicting drug sensitivity that is not available from the corresponding mRNAs. We also developed a user-friendly bioinformatic resource, MCLP, to help serve the biomedical research community.

SMARCA4-inactivating mutations increase sensitivity to Aurora kinase A inhibitor VX-680 in non-small cell lung cancers

Mutations in the SMARCA4/BRG1 gene resulting in complete loss of its protein (BRG1) occur frequently in non-small cell lung cancer (NSCLC) cells. Currently, no single therapeutic agent has been identified as synthetically lethal with SMARCA4/BRG1 loss. We identify AURKA activity as essential in NSCLC cells lacking SMARCA4/BRG1. In these cells, RNAi-mediated depletion or chemical inhibition of AURKA induces apoptosis and cell death in vitro and in xenograft mouse models. Disc large homologue-associated protein 5 (HURP/DLGAP5), required for AURKA-dependent, centrosome-independent mitotic spindle assembly is essential for the survival and proliferation of SMARCA4/BRG1 mutant but not of SMARCA4/BRG1 wild-type cells. AURKA inhibitors may provide a therapeutic strategy for biomarker-driven clinical studies to treat the NSCLCs harbouring SMARCA4/BRG1-inactivating mutations.

Lung cancers often harbour loss-of-function mutations in SMARCA4. Here, the authors demonstrate a vulnerability of SMARCA4-deficient lung cancers for Aurora kinase A inhibition associated with mitotic defects.

Proportion of Never-Smoker Non-Small Cell Lung Cancer Patients at Three Diverse Institutions

Background

Approximately 10% to 15% of lung cancer cases in the United States occur in never smokers, but there has been much debate about whether this rate is increasing. To determine whether the proportion of never smokers among lung cancer cases is increasing, we conducted a retrospective study using registries from The University of Texas Southwestern Medical Center, Parkland Hospital, and Vanderbilt University.

Methods

Registries were queried for demographic information from 1990 to 2013 including sex, age, stage, and self-reported smoking history. Ten thousand five hundred ninety-three non-small cell lung cancer (NSCLC) case patients and 1510 small cell lung cancer (SCLC) case patients were captured, and logistic regression analysis was performed. All statistical tests were two-sided.

Results

The proportion of never-smoker NSCLC patients increased from 8.0% in the years 1990 to 1995 to 14.9% in 2011 to 2013 (P < .001). This increase was also observed using multivariable logistic regression after controlling for sex, stage at diagnosis, and race/ethnicity. The percentage of never smokers among SCLC case patients (1.5% in 1990-1995 to 2.5% in 2011-2013, P = .36) or squamous cell NSCLC case patients did not statistically significantly change during this period.

Conclusions

This study demonstrates an increasing proportion of NSCLC patients who have never smoked in a large, diverse patient population between 1990 and 2013. Given that this increase appears independent of sex, stage, and race/ethnicity and also occurred in our county hospital, this trend is unlikely due to changes in referral patterns and suggests that the actual incidence of lung cancer in never smokers is increasing.

SHOX2 is a Potent Independent Biomarker to Predict Survival of WHO Grade II-III Diffuse Gliomas

Background

Diffuse gliomas, grades II and III, hereafter called lower-grade gliomas (LGG), have variable, difficult to predict clinical courses, resulting in multiple studies to identify prognostic biomarkers. The purpose of this study was to assess expression or methylation of the homeobox family gene SHOX2 as independent markers for LGG survival.

Methods

We downloaded publically available glioma datasets for gene expression and methylation. The Cancer Genome Atlas (TCGA) (LGG, n = 516) was used as a training set, and three other expression datasets (n = 308) and three other methylation datasets (n = 320), were used for validation. We performed Kaplan-Meier survival curves and univariate and multivariate Cox regression model analyses.

Findings

SHOX2 expression and gene body methylation varied among LGG patients and highly significantly predicted poor overall survival. While they were tightly correlated, SHOX2 expression appeared more potent as a prognostic marker and was used for most further studies. The SHOX2 prognostic roles were maintained after analyses by histology subtypes or tumor grade. We found that the combination of SHOX2 expression and IDH genotype status identified a subset of LGG patients with IDH wild-type (IDHwt) and low SHOX2 expression with considerably favorable survival. We further investigated the combination of SHOX2 with other known clinically relevant markers of LGG (TERT expression, 1p/19q chromosome co-deletion, MGMT methylation, ATRX mutation and NES expression). When combined with SHOX2 expression, we identified subsets of LGG patients with significantly favorable survival outcomes, especially in the subgroup with worse prognosis for each individual marker. Finally, multivariate analysis demonstrated that SHOX2 was a potent independent survival marker.

Interpretation

We have identified that SHOX2 expression or methylation are potent independent prognostic indicators for predicting LGG patient survival, and have potential to identify an important subset of LGG patients with IDHwt status with significantly better overall survival. The combination of IDH or other relevant markers with SHOX2 identified LGG subsets with significantly different survival outcomes, and further understanding of these subsets may benefit therapeutic target identification and therapy selections for glioma patients.

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SHOX2 is a potent independent prognostic indicator for grade II and III diffuse gliomas. SHOX2 in combination with IDH has the potential to identify important diffuese gliomas subsets with significantly better survivals. SHOX2 in combination with other markers is potentially useful for identifying distinct prognostic subsets of diffuse gliomas.

Diffuse glioma brain tumors (gliomas encompassing astrocytomas and oligodedrogliomas, grades II and III), have highly variable, difficult to predict clinical courses and a number of specific alterations have been identified that have prognostic or therapeutic implications, whether as single markers or in various combinations. The use of mutation status of the isocitrate dehydrogenase (IDH) enzyme genes has been demonstrated to be a potent prognostic marker greatly improving survival prognosis. SHOX2 methylation was suggested to be associated with lung and breast cancers. In this study we assessed SHOX2 gene methylation and expression as independent markers for diffuse gliomas survival prognosis, by multiple statistical survival analyses of multiple genome-wide datasets. We have identified that SHOX2 is a potent independent prognostic marker, both by itself and in combination with other markers (IDH mutation status, 1p/19q codeltion, ATRX mutation, nestin or TERT expression and MGMT methylation), and potentially useful for refining the molecular classification of diffuse gliomas, and for distinguishing clinically distinct prognostic subgroups of gliomas patients for better therapy selection.

ZEB1 drives epithelial-to-mesenchymal transition in lung cancer

Increased expression of zinc finger E-box binding homeobox 1 (ZEB1) is associated with tumor grade and metastasis in lung cancer, likely due to its role as a transcription factor in epithelial-to-mesenchymal transition (EMT). Here, we modeled malignant transformation in human bronchial epithelial cells (HBECs) and determined that EMT and ZEB1 expression are early, critical events in lung cancer pathogenesis. Specific oncogenic mutations in TP53 and KRAS were required for HBECs to engage EMT machinery in response to microenvironmental (serum/TGF-β) or oncogenetic (MYC) factors. Both TGF-β- and MYC-induced EMT required ZEB1, but engaged distinct TGF-β-dependent and vitamin D receptor-dependent (VDR-dependent) pathways, respectively. Functionally, we found that ZEB1 causally promotes malignant progression of HBECs and tumorigenicity, invasion, and metastases in non-small cell lung cancer (NSCLC) lines. Mechanistically, ZEB1 expression in HBECs directly repressed epithelial splicing regulatory protein 1 (ESRP1), leading to increased expression of a mesenchymal splice variant of CD44 and a more invasive phenotype. In addition, ZEB1 expression in early stage IB primary NSCLC correlated with tumor-node-metastasis stage. These findings indicate that ZEB1-induced EMT and associated molecular changes in ESRP1 and CD44 contribute to early pathogenesis and metastatic potential in established lung cancer. Moreover, TGF-β and VDR signaling and CD44 splicing pathways associated with ZEB1 are potential EMT chemoprevention and therapeutic targets in NSCLC.

ASCL1 and NEUROD1 Reveal Heterogeneity in Pulmonary Neuroendocrine Tumors and Regulate Distinct Genetic Programs

Small cell lung carcinoma (SCLC) is a high-grade pulmonary neuroendocrine tumor. The transcription factors ASCL1 and NEUROD1 play crucial roles in promoting malignant behavior and survival of human SCLC cell lines. Here, we find that ASCL1 and NEUROD1 identify heterogeneity in SCLC, bind distinct genomic loci, and regulate mostly distinct genes. ASCL1, but not NEUROD1, is present in mouse pulmonary neuroendocrine cells, and only ASCL1 is required in vivo for tumor formation in mouse models of SCLC. ASCL1 targets oncogenic genes including MYCL1, RET, SOX2, and NFIB while NEUROD1 targets MYC. ASCL1 and NEUROD1 regulate different genes that commonly contribute to neuronal function. ASCL1 also regulates multiple genes in the NOTCH pathway including DLL3. Together, ASCL1 and NEUROD1 distinguish heterogeneity in SCLC with distinct genomic landscapes and distinct gene expression programs.

Abstract LB-318: SMARCA4-inactivating mutations increase sensitivity to Aurora kinase A-targeted therapies in non-small cell lung cancers (NSCLCs)

Purpose: Here, we sought to identify critical genes, whose depletion and inhibition caused differential cytotoxicity in SMARCA4-mutant non-small cell lung cancers (NSCLCs).

Background: The SWI/SNF complex is a master regulator of gene expression, affecting at least 10% of the transcriptome. Because of its crucial role in controlling cell cycle, development and differentiation, the SWI/SNF complex components function as tumor suppressor genes. Therefore, not surprisingly, the ATPases SMARCA2 and SMARCA4 are frequently down-regulated in cancers and mutations of SMARCA4 are frequently present in many cancer types including lung cancers. However, currently, no single therapeutic agent has been identified as synthetically lethal with SMARCA4 loss.

To identify SMARCA4-inactivating mutation related targetable gene products, we developed and applied a high throughput cell-based one-well/one-gene screening platform with a genome-wide synthetic library of chemically synthesized small interfering RNAs. Using this approach, we have identified a molecular target (SMARCA4) frequently present in lung cancer cells, whose loss leads to increased sensitivity to a class of Aurora kinase A inhibitors.

Materials, Methods and Results: SMARCA4-mutant NSCLC line NCI-H1819 was screened with a genome-wide library of ∼22,000 pools of 4 siRNA oligonucleotides, identifying 38 pools that were 50% more toxic than the median toxicity in the screen, and were not toxic for wild-type SMARCA4-expressing HBEC30-KT cells. Among our high-priority toxic siRNAs, a number of targeted genes encode proteins important for the cell cycle, including RAN and TPX2. RAN is required for TPX2 to function in mitosis and TPX2 binds to microtubules and activates Aurora kinase A. Individual siRNAs targeting these “hits” in the primary screen, as well as siRNA to Aurora kinase A, were tested and shown to inhibit the growth of NCI-H1819, but not HBECs. In addition, NCI-H1819 cells were hyper-sensitive to VX-680, an inhibitor of Aurora kinases.

We then tested a panel of other NSCLC cell lines that either expressed or did not express wild-type SMARCA4 for sensitivity to siRNA targeting Aurora kinase A, or VX-680. The cell lines with loss of SMARCA4 were more sensitive to loss of AURKA or to VX-680 than NSCLC or HBEC cells expressing SMARCA4. Our observations were further expanded and validated with xenograft mouse models.

Next, we explored why AURKA-targeted therapy causes differential toxicity to the NSCLCs with SMARCA4 loss and identified centrosomal impairments in SMARCA4-null NSCLC cells that create defective mitotic spindle assembly machinery.

Conclusions: SMARCA4-inactivating mutations make cells dependent to RAN/TPX2-mediated mitotic spindle assembly machinery and create targetable mitotic vulnerabilities in NSCLCs.

SMARCA4-mutant NSCLCs are sensitive to Aurora kinase A-targeted treatments due to its crucial role on RAN/TPX2-dependent mitotic spindle formation.

Our data suggest that wild-type SMARCA4-expressing cells tolerate the inhibition of AURKA due to properly regulated and, therefore, functionally normal centrosomes whereas SMARCA4 loss leads to centrosomal defects.

Citation Format: Vural Tagal, Shuguang Wei, Wei Zhang, Rolf A. Brekken, Bruce A. Posner, Adi F. Gazdar, Michael G. Roth. SMARCA4-inactivating mutations increase sensitivity to Aurora kinase A-targeted therapies in non-small cell lung cancers (NSCLCs). [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 LB-318.

An Expression Signature as an Aid to the Histologic Classification of Non-Small Cell Lung Cancer

PURPOSE

Most non-small cell lung cancers (NSCLC) are now diagnosed from small specimens, and classification using standard pathology methods can be difficult. This is of clinical relevance as many therapy regimens and clinical trials are histology dependent. The purpose of this study was to develop an mRNA expression signature as an adjunct test for routine histopathologic classification of NSCLCs.

EXPERIMENTAL DESIGN

A microarray dataset of resected adenocarcinomas (ADC) and squamous cell carcinomas (SCC) was used as the learning set for an ADC-SCC signature. The Cancer Genome Atlas (TCGA) lung RNAseq dataset was used for validation. Another microarray dataset of ADCs and matched nonmalignant lung was used as the learning set for a tumor versus nonmalignant signature. The classifiers were selected as the most differentially expressed genes and sample classification was determined by a nearest distance approach.

RESULTS

We developed a 62-gene expression signature that contained many genes used in immunostains for NSCLC typing. It includes 42 genes that distinguish ADC from SCC and 20 genes differentiating nonmalignant lung from lung cancer. Testing of the TCGA and other public datasets resulted in high prediction accuracies (93%-95%). In addition, a prediction score was derived that correlates both with histologic grading and prognosis. We developed a practical version of the Classifier using the HTG EdgeSeq nuclease protection-based technology in combination with next-generation sequencing that can be applied to formalin-fixed paraffin-embedded (FFPE) tissues and small biopsies.

CONCLUSIONS

Our RNA classifier provides an objective, quantitative method to aid in the pathologic diagnosis of lung cancer. Clin Cancer Res; 22(19); 4880-9. ©2016 AACR.

A comprehensively characterized cell line panel highly representative of clinical ovarian high-grade serous carcinomas

Recent literature suggests that most widely used ovarian cancer (OVCA) cell models do not recapitulate the molecular features of clinical tumors. To address this limitation, we generated 18 cell lines and 3 corresponding patient-derived xenografts predominantly from high-grade serous carcinoma (HGSOC) peritoneal effusions. Comprehensive genomic characterization and comparison of each model to its parental tumor demonstrated a high degree of molecular similarity. Our characterization included whole exome-sequencing and copy number profiling for cell lines, xenografts, and matched non-malignant tissues, and DNA methylation, gene expression, and spectral karyotyping for a subset of specimens. Compared to the Cancer Genome Atlas (TCGA), our models more closely resembled HGSOC than any other tumor type, justifying their validity as OVCA models. Our meticulously characterized models provide a crucial resource for the OVCA research community that will advance translational findings and ultimately lead to clinical applications.

Validation of SCT Methylation as a Hallmark Biomarker for Lung Cancers

INTRODUCTION

The human secretin gene (SCT) encodes secretin, a hormone with limited tissue distribution. Analysis of the 450k methylation array data in The Cancer Genome Atlas (TCGA) indicated that the SCT promoter region is differentially hypermethylated in lung cancer. Our purpose was to validate SCT methylation as a potential biomarker for lung cancer.

METHODS

We analyzed data from TCGA and developed and applied SCT-specific bisulfite DNA sequencing and quantitative methylation-specific polymerase chain reaction assays.

RESULTS

The analyses of TCGA 450K data for 801 samples showed that SCT hypermethylation has an area under the curve (AUC) value greater than 0.98 that can be used to distinguish lung adenocarcinomas or squamous cell carcinomas from nonmalignant lung tissue. Bisulfite sequencing of lung cancer cell lines and normal blood cells allowed us to confirm that SCT methylation is highly discriminative. By applying a quantitative methylation-specific polymerase chain reaction assay, we found that SCT hypermethylation is frequently detected in all major subtypes of malignant non-small cell lung cancer (AUC = 0.92, n = 108) and small cell lung cancer (AUC = 0.93, n = 40) but is less frequent in lung carcinoids (AUC = 0.54, n = 20). SCT hypermethylation appeared in samples of lung carcinoma in situ during multistage pathogenesis and increased in invasive samples. Further analyses of TCGA 450k data showed that SCT hypermethylation is highly discriminative in most other types of malignant tumors but less frequent in low-grade malignant tumors. The only normal tissue with a high level of methylation was the placenta.

CONCLUSIONS

Our findings demonstrated that SCT methylation is a highly discriminative biomarker for lung and other malignant tumors, is less frequent in low-grade malignant tumors (including lung carcinoids), and appears at the carcinoma in situ stage.

Abstract A22: Differential MYC dependence in NSCLC identified through pharmacological and genetic MYC inhibition

MYC is one of the most commonly deregulated oncogenes in various cancers, including breast, colorectal and lung. While mutations are rare, we know that MYC is overexpressed and in some cases amplified in these (and other) cancers. Numerous reports have recently demonstrated the utility of various therapeutics in selectively targeting MYC-driven cancers. However, given the lack of consistency across tissue types, particularly lung cancer, a multimodal approach to delineate MYC-dependent lung cancers is required. Our goal is to identify lung cancers that are addicted to MYC, determine their oncogenotype and molecular properties, and identify a biomarker to identify patients with MYC addicted tumors. We studied a large panel of clinically and molecularly annotated NSCLC lines for MYC mRNA, protein expression, and DNA copy number. Functional tests were performed on 17 NSCLC cell lines using three drugs that were recently shown to selectively target MYC-driven cancers. Further, we utilized the dominant negative mini-protein OMOMYC for functional classification. In all cases, effects were monitored by colony forming efficiency (CFE) assays and proliferation assays. OMOMYC results were confirmed via xenograft experiments. Each of the three MYC inhibitors tested elicited a viability response in a subset of the 17 NSCLC cell lines, though the sensitive subset was not significantly similar between any two drugs (highest correlation coefficient of 0.3). In order to determine which, if any, of the drugs truly targeted MYC-driven lung cancers, we stably expressed OMOMYC in all 17 parental NSCLC cells and performed functional assays. 6/17 cell lines were dramatically sensitive to OMOMYC (with up to 100 fold reduction in CFE), compared to 11/17 totally resistant. The viability in the presence of OMOMYC shows a statistically significant correlation with one of the three MYC inhibitors tested, which supports the notion that this sensitive subset represents a truly MYC-dependent class of lung cancers. Surprisingly, there was no correlation between MYC dependence and either MYC mRNA, protein expression or DNA copy number. OMOMYC levels were normalized in all cell lines tested and quantified using qRT-PCR. Additionally, in all cases, exogenous OMOMYC expression led to down regulation of c-Myc target genes as measured by both qRT-PCR and microarray. These data suggest that the observed phenotype was the result of decreased MYC activity. We conclude: there is a subset of NSCLCs that demonstrates dramatic growth inhibition by a single MYC-inhibitor, and these data are phenocopied by the more specific MYC-dominant negative protein, OMOMYC. We are classifying this subset of cancer cell lines, MYC “addicted.” Using the MYC “addicted” vs. non- addicted NSCLC panel, we are testing for gene expression, methylation and mutational differences in order to identify and eventually characterize a biomarker for MYC dependence in lung cancer.

Citation Format: Patrick Dospoy, Chunli Shao, Elizabeth McMillan, Michael Peyton, Jill Larsen, Luc Girard, Ignacio Wistuba, Adi F. Gazdar, John D. Minna. Differential MYC dependence in NSCLC identified through pharmacological and genetic MYC inhibition. [abstract]. In: Proceedings of the AACR Special Conference on Myc: From Biology to Therapy; Jan 7-10, 2015; La Jolla, CA. Philadelphia (PA): AACR; Mol Cancer Res 2015;13(10 Suppl):Abstract nr A22.

SCT Promoter Methylation is a Highly Discriminative Biomarker for Lung and Many Other Cancers

Aberrant DNA methylation has long been implicated in cancers. In this work we present a highly discriminative DNA methylation biomarker for non-small cell lung cancers and fourteen other cancers. Based on 69 NSCLC cell lines and 257 cancer-free lung tissues we identified a CpG island in SCT gene promoter which was verified by qMSP experiment in 15 NSCLC cell lines and 3 immortalized human respiratory epithelium cells. In addition, we found that SCT promoter was methylated in 23 cancer cell lines involving >10 cancer types profiled by ENCODE. We found that SCT promoter is hyper-methylated in primary tumors from TCGA lung cancer cohort. Additionally, we found that SCT promoter is methylated at high frequencies in fifteen malignancies and is not methylated in~1000 non-cancerous tissues across >30 organ types. Our study indicates that SCT promoter methylation is a highly discriminative biomarker for lung and many other cancers.

Abstract 4762: ITPKA expression in lung and other cancers, regulated via gene body methylation, functions as an oncogene

Inositol-Trisphosphate 3-Kinase A (ITPKA), a kinase with limited tissue distribution, is involved in inositol phosphate metabolism. We identified ITPKA as up-regulated in lung and many other types of cancers. Using gain-of-function and loss-of-function approaches, we demonstrated by in vitro and in vivo assays that ITPKA functions as an oncogene to drive the development of lung cancer. We further showed that methylation level in the ITPKA gene body is significantly higher in various types of primary tumors than in corresponding non-malignant tissues, which was positively correlated with its expression. Our study revealed that DNMT3B-mediated methylation of the CpG island in ITPKA gene body regulates its expression via modulation of the binding of transcription activator SP1 to the ITPKA promoter. During the multistage pathogenesis of lung carcinoma, ITPKA gene body methylation first appeared at the in situ carcinoma stage and increased during disease progression. Thus ITPKA expression functions as an oncogene in lung and other cancers. Highly specific and sensitive expression and methylation of ITPKA was present in a wide range of tumor types, suggesting that deregulation of ITPKA may function as a universal or near universal hallmark of malignancy.

Citation Format: Yi-Wei Wang, Xiaotu Ma, Yu-An Zhang, Mei-Jung Wang, Yasushi Yatabe, Stephen Lam, Luc Girard, Jeou-Yuan Chen, Adi F. Gazdar. ITPKA expression in lung and other cancers, regulated via gene body methylation, functions as an oncogene. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 4762. doi:10.1158/1538-7445.AM2015-4762

Abstract 225: Assessing and enriching human tumor cell content in patient-derived cancer xenografts and co-cultures

Purpose: To develop a robust real-time PCR-based assay with improved accuracy for quantifying the relative fractions of human and mouse DNA in heterogeneous samples such as patient-derived cancer xenografts or cultures. Background: Patient derived mouse xenografts (PDXs), or irradiated mouse fibroblast conditionally reprogrammed cancer cultures (CRCs) provide valuable resources for studying cancers, but as mouse tissue in heterogeneous samples can significantly confound downstream functional and molecular assays (such as next-generation sequencing) it is important to determine the fraction of mouse DNA in mixed samples. Methods: Using an approach different from a previously reported PCR assay (Alcoser SY et al BMC Biotech 2011, 11:124), we established a Taqman real-time PCR assay employing mouse- and human-specific primers that amplified the same chromosomal region of PTGER2 on human chromosome 14q22.1 and mouse chromosome 14 22.68 cM. We also developed a method to enrich human tumor cells from PDXs using enzymatic digestion with Liberase (Roche), followed by differential centrifugation and adherence. Results: Utilizing serial dilutions of heterogeneous DNA mixtures of mouse spleen DNA and normal human white blood cell DNA at varied DNA ratios we demonstrated the assay to be linear (Pearson r = 0.9984, human DNA; r = 0.9998, mouse DNA; p&lt;0.0001) and sensitive (&gt;6.4 pg DNA/reaction). The assay was evaluated in 66 samples of human tumors (lung, ovary, neuroblastoma, colon, pancreas, stomach and melanoma) including 25 PDXs before and after tumor cell enrichment, 12 non-enriched PDXs, 2 CRC-derived xenografts and 2 CRCs. Of the PDXs 28 were subcutaneous tumors and 9 were malignant ascites. A wide range of human:mouse DNA ratios were found from zero to 99% among all samples, with two PDXs and 2 CRC-derived xenografts lacking detectable human DNA. The highest human cell fractions were in the malignant ascites samples. Of the enriched samples, 18 of 25 (72%) showed tumor cell enrichment of 2 to 71-fold as compared with the value of matching non-enriched PDX. Conclusions: We developed a robust real-time PCR assay for measuring the relative fraction of species-specific DNA in human:mouse heterogenous samples. The human:mouse DNA ratios in PDX samples varied widely and the human tumor cell populations in PDXs can be effectively enriched in vitro. Assessing human tumor cell content with this assay will facilitate molecular studies with PDXs and mouse-human cocultivated cells.

Citation Format: Yu-An Zhang, Victor Stastny, Mahboubeh Papari-Zareei, Heather Davidson, Boning Gao, Brenda Timmons, Jingsheng Yan, C Patrick Reynolds, John D. Minna, Adi F. Gazdar. Assessing and enriching human tumor cell content in patient-derived cancer xenografts and co-cultures. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 225. doi:10.1158/1538-7445.AM2015-225

Abstract 613: Copy number variations distinguish lung adenocarcinomas from squamous cell carcinomas

Purpose

To develop a molecular based classification of non-small cell lung carcinomas based on genome wide copy number variations (CNVs).

Background

For a number of clinical and biologic reasons, the accurate classification of non small cell lung carcinoma (NSCLC) into adenocarcinoma (ADC) and squamous cell carcinoma (SCC) is essential. DNA based tests, which are not currently used, are more robust when applied to formalin fixed paraffin embedded tissues.

Materials and Methods

TCGA Dataset: The Cancer Genome Atlas project (TCGA) level 3 CNVs data (Affymetrix Genome-Wide Human SNP Array 6.0) of resected ADC (n = 241) and SCC (n = 210) patients were utilized as a Training set along with 1091 non malignant lung samples.

SPORE Patient Dataset: The UT Lung SPORE cohort consists of 248 resected lung cancers (168 ADC and 74 SCC samples) run with the Agilent 244K Human Genome CGH Microarray.

Molecular signature identification based on the morphologic subclassification of NSCLC: We used statistical algorithms to identify potential CNV biomarkers and combined them with known amplified oncogenes to identify 28 CNV signature genes that were highly correlated with histological classification.

Identification of CNV classifier genes. The CNV signature genes were identified through the following four sequential steps: 1) Paired t-test. 2) Elastic Net. 3) Partial lease squares algorithm. 4) Naive Bayes classifier.

Results:

The 28 gene CNV signature accurately separated squamous cell carcinomas from adenocarcinomas in the Training and Validation sets as well as distinguished tumors from non-malignant tissues (Table 1).

Table 1. The classification results between ADC and SCC

DataSensitivitySpecificityAccuracyADC vs SCCTraining set (TCGA)0.940.870.91Validation set (SPORE)0.870.840.86Tumor vs Non-malignantADC0.910.960.94SCC0.970.980.98

Conclusions: A 28 gene CNV signature distinguished lung adenocarcinomas from squamous cell carcinomas with great accuracy (86-91%) and the lung tumor samples can be distinguished from the non-malignant lung samples with an accuracy of 94-98%.

Citation Format: Kai Song, Guangqiang Zheng, Luc Girard, Ignacio I. Wistuba, Jack A. Roth, Carmen Behrens, Milind B. Suraokar, John D. Minna, Adi F. Gazdar. Copy number variations distinguish lung adenocarcinomas from squamous cell carcinomas. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 613. doi:10.1158/1538-7445.AM2015-613