Orchestrating Resilience: How Neuropilin-2 and Macrophages Contribute to Cardiothoracic Disease

Immunity has evolved to balance the destructive nature of inflammation with wound healing to overcome trauma, infection, environmental insults, and rogue malignant cells. The inflammatory response is marked by overlapping phases of initiation, resolution, and post-resolution remodeling. However, the disruption of these events can lead to prolonged tissue damage and organ dysfunction, resulting long-term disease states. Macrophages are the archetypic phagocytes present within all tissues and are important contributors to these processes. Pleiotropic and highly plastic in their responses, macrophages support tissue homeostasis, repair, and regeneration, all while balancing immunologic self-tolerance with the clearance of noxious stimuli, pathogens, and malignant threats. Neuropilin-2 (Nrp2), a promiscuous co-receptor for growth factors, semaphorins, and integrins, has increasingly been recognized for its unique role in tissue homeostasis and immune regulation. Notably, recent studies have begun to elucidate the role of Nrp2 in both non-hematopoietic cells and macrophages with cardiothoracic disease. Herein, we describe the unique role of Nrp2 in diseases of the heart and lung, with an emphasis on Nrp2 in macrophages, and explore the potential to target Nrp2 as a therapeutic intervention.

Isoforms of Neuropilin-2 Denote Unique Tumor-Associated Macrophages in Breast Cancer

Tumor-associated macrophages (TAMs) exert profound influence over breast cancer progression, promoting immunosuppression, angiogenesis, and metastasis. Neuropilin-2 (NRP2), consisting of the NRP2a and NRP2b isoforms, is a co-receptor for heparin-binding growth factors including VEGF-C and Class 3 Semaphorins. Selective upregulation in response to environmental stimuli and independent signaling pathways endow the NRP2 isoforms with unique functionality, with NRP2b promoting increased Akt signaling via receptor tyrosine kinases including VEGFRs, MET, and PDGFR. Although NRP2 has been shown to regulate macrophage/TAM biology, the role of the individual NRP2a/NRP2b isoforms in TAMs has yet to be evaluated. Using transcriptional profiling and spectral flow cytometry, we show that NRP2 isoform expression was significantly higher in TAMs from murine mammary tumors. NRP2a/NRP2b levels in human breast cancer metastasis were dependent upon the anatomic location of the tumor and significantly correlated with TAM infiltration in both primary and metastatic breast cancers. We define distinct phenotypes of NRP2 isoform-expressing TAMs in mouse models of breast cancer and within malignant pleural effusions from breast cancer patients which were exclusive of neuropilin-1 expression. Genetic depletion of either NRP2 isoform in macrophages resulted in a dramatic reduction of LPS-induced IL-10 production, defects in phagosomal processing of apoptotic breast cancer cells, and increase in cancer cell migration following co-culture. By contrast, depletion of NRP2b, but not NRP2a, inhibited production of IL-6. These results suggest that NRP2 isoforms regulate both shared and unique functionality in macrophages and are associated with distinct TAM subsets in breast cancer.

Abstract 2994: Inhibition of the NRP2b:GSK3β binding interaction with peptides and macrocycles exerts anticancer effects in lung cancer

Introduction: Neuropilin-2b (NRP2b) expression is associated with pro-tumorigenic properties of NSCLCs. We previously reported that NRP2b promotes metastasis and drug resistance, while the canonical NRP2a isoform is inhibitory. Our recent work indicates that the NRP2b cytoplasmic domain recruits GSK3β to phosphorylate and promote degradation of co-recruited PTEN, thereby enhancing AKT activity leading to enhanced survival, migration and drug resistance. We identified a 15-amino acid motif near the NRP2b C-terminus required for interaction with GSK3β. Herein, we describe the anticancer effect of peptides and drug-like macrocycles designed to disrupt this interaction.

Methods: We used the cytoplasmic sequence of NRP2b for decoy peptides designed to disrupt the interaction with GSK3β. Control peptides were synthesized with alanine replacements for three amino acids suggested as crucial for GSK3β recruitment. All peptides were N-terminally myristoylated to promote association with and flipping to the inner leaflet of the plasma membrane. A library of over 42,000 drug-like macrocycles was screened in silico for compounds predicted to fit and compete with the NRP2b:GSK3β binding interface. Decoy peptides and macrocycles were assessed for anti-NRP2b activity using assays for migration and drug-tolerant persister cells. Transwell migration assays were performed using a Neuro Probe Reusable Multiwell Chemotaxis Chamber. Persister cell assays were performed with EGFR mutant PC9 and HCC827 cells in the presence of EGFR inhibitors (gefitinib or osimertinib), followed by drug withdrawal and colony formation assays.

Results: As previously reported, knockdown of NRP2b inhibited, while knockdown of NRP2a enhanced, migration of lung cancer cell lines. Importantly, emergence of drug-tolerant persister cells was similarly inhibited by knockdown of NRP2b and enhanced by knockdown of NRP2a. Wild type, but not control, peptides abrogated the pro-tumorigenic effects of NRP2a knockdown on both migration and persister cell formation with IC50s of ~250 nM. The most effective macrocycles, M3 and M7, inhibited NRP2b-dependent migration with IC50s of 1-3 µM. Both macrocycles also inhibited generation of persister cell colonies from shNRP2a-PC-9 cells. However, only M3 was effective at blocking persisters from shNRP2a-HCC827 cells.

Conclusions: NRP2b:GSK3β interaction is a therapeutic target in NSCLC affecting migration/invasion and persister colony formation associated with the emergence of resistance to EGFR inhibitors. This work justifies further development of these peptides and drug-like macrocycles as therapeutic modalities in lung cancer.

Citation Format: Cecile Nasarre, Yuri K. Peterson, Patrick Nasarre, Anastasios Dimou, Kent E. Armeson, Harry A. Drabkin, Nancy Demore, Chadrick E. Denlinger, Robert M. Gemmill. Inhibition of the NRP2b:GSK3β binding interaction with peptides and macrocycles exerts anticancer effects in lung cancer [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 2994.

Neuropilin-2b facilitates resistance to tyrosine kinase inhibitors in non-small cell lung cancer

OBJECTIVE

Innate and acquired resistance is the principle factor limiting the efficacy of tyrosine kinase inhibitors in lung cancer. We have observed a dramatic upregulation of the cell surface co-receptor neuropilin-2b in lung cancers clinically treated with tyrosine kinase inhibitors correlating with acquired resistance. We hypothesize that neuropilin-2b plays a functional role in acquired tyrosine kinase inhibitor resistance.

METHODS

Non-small cell lung cancer proliferation and survival were determined during chronic tyrosine kinase inhibitor exposure in the presence or absence of neuropilin-2b knock-down. Interactions of neuropilin-2a and neuropilin-2b isoforms with PTEN and GSK3β were assessed by immunoprecipitation. Neuropilin-2a and neuropilin-2b mutants deleted for their cytoplasmic domains were used to identify regions responsible for neuropilin-2b-GSK3β interaction. Because GSK3β is known to phosphorylate and degrade PTEN, phospho-PTEN and total PTEN levels were assessed after transfection of neuropilin-2a and neuropilin-2b wild-type and mutant constructs.

RESULTS

Non-small cell lung cancer cells chronically treated with gefitinib or osimertinib developed drug resistance and exhibited logarithmic growth in the presence of endothelial growth factor receptor tyrosine kinase inhibitors. However, neuropilin-2b knockdown cells remained sensitive to gefitinib. Likewise, neuropilin-2b knockdown suppressed and neuropilin-2a knockdown enhanced cellular migration. Acquired drug resistance and cell migration correlated with neuropilin-2b-dependent AKT activation with the intermediate step of GSK3β-dependent PTEN degradation. A specific binding site for GSK3β on the cytoplasmic domain of neuropilin-2b was identified with truncated protein constructs and computer modeling.

CONCLUSIONS

Neuropilin-2b facilitates non-small cell lung cancer resistance to tyrosine kinase inhibitors, and this biological effect relates to AKT activation. Neuropilin-2b GSK3β interactions appear to be essential for PTEN degradation and AKT activation in lung cancer cells. Disruption of the neuropilin-2b GSK3β interaction may represent a novel treatment strategy to preserve sensitivity to tyrosine kinase inhibitors in non-small cell lung cancer.

Abstract 2624: NRP2b promotes migration, drug resistance and AKT activation in lung cancers by recruiting GSK3â to phosphorylate and destabilize PTEN

Background: Neuropilins (NRPs) are cell surface co-receptors known to enhance signaling from multiple ligands, including growth factors and their cognate receptors, such as HGF/MET. We have previously shown that the novel “b” isoform of NRP2 (NRP2b) is specifically associated with aggressive NSCLC and is required for TGFβ-induced EMT. We also found that NRP2b promotes AKT activation, drug resistance and metastatic spread, while the canonical NRP2a isoform inhibits these processes. However, the mechanisms supporting these differential functions remain obscure.

Results: Live cell imaging revealed that NRP2b expression led to slow internalization/rapid surface recycling of HGF-bound MET compared to NRP2a, which promoted rapid internalization and little/no recycling. Co-immunoprecipitation experiments showed that GSK3β interacted robustly with NRP2b, but only weakly with NRP2a. Our previous work demonstrated analogous differential recruitment of PTEN, but with reversed preferences; i.e., robust binding to NRP2a, but weak binding to NRP2b. Importantly, GSK3β inhibition blocked HGF-dependent migration of lung cancer cells expressing NRP2b, but not in cells expressing NRP2a. Given that PTEN is an established target of GSK3β, and that modification by GSK3β leads to its proteasome-mediated degradation, PTEN levels were examined in cells expressing individual NRP2 isoforms. PTEN was significantly reduced by expression of NRP2b, but not by NRP2a. The reduction of PTEN in the presence of NRP2b was blocked by inhibition of GSK3β, and by proteasome inhibition with MG132. Despite lower PTEN levels, phosphorylation of the GSK3β target site on Thr366 was specifically increased by NRP2b. Co-immunoprecipitation of GSK3β with NRP2b deletion mutants identified a C-terminal 15 amino acid peptide as the site of interaction. Mutants without this sequence failed to recruit GSK3β and failed to reduce PTEN levels. In silico modeling of this peptide suggested an amphipathic alpha-helical structure with a high affinity docking site (ΔG = -45 kcal) on the atomic structure of GSK3β.

Conclusion: Our results suggest that NRP2b promotes receptor signaling to AKT by differential endosomal trafficking and by recruitment of GSK3β. This kinase will phosphorylate and destabilize active PTEN recruited into the complex by NRP2a, which heterodimerizes with NRP2b. Increased AKT signaling following PTEN loss is likely responsible for the pro-tumorigenic properties of NRP2b, including resistance to targeted agents and metastatic spread. This novel mechanism for NRP2b function suggests that targeting its interaction with GSK3β might be a fruitful therapeutic strategy to reduce drug resistance and/or metastatic spread in lung cancer.

Citation Format: Anastasios Dimou, Cecile Nasarre, Monika Gooz, Rose Pagano, Yuri Peterson, Kent Armeson, Harry A. Drabkin, Patrick Nasarre, Chadrick E. Denlinger, Robert M. Gemmill. NRP2b promotes migration, drug resistance and AKT activation in lung cancers by recruiting GSK3â to phosphorylate and destabilize PTEN [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 2624.

CD47 is a direct target of SNAI1 and ZEB1 and its blockade activates the phagocytosis of breast cancer cells undergoing EMT

We report that CD47 was upregulated in different EMT-activated human breast cancer cells versus epithelial MCF7 cells. Overexpression of SNAI1 or ZEB1 in epithelial MCF7 cells activated EMT and upregulated CD47 while siRNA-mediated targeting of SNAI1 or ZEB1 in mesenchymal MDA-MB-231 cells reversed EMT and strongly decreased CD47. Mechanistically, SNAI1 and ZEB1 upregulated CD47 by binding directly to E-boxes in the human CD47 promoter. TCGA and METABRIC data sets from breast cancer patients revealed that CD47 correlated with SNAI1 and Vimentin. At functional level, different EMT-activated breast cancer cells were less efficiently phagocytosed by macrophages vs. MCF7 cells. The phagocytosis of EMT-activated cells was rescued by using CD47 blocking antibody or by genetic targeting of SNAI1, ZEB1 or CD47. These results provide a rationale for an innovative preclinical combination immunotherapy based on PD-1/PD-L1 and CD47 blockade along with EMT inhibitors in patients with highly aggressive, mesenchymal, and metastatic breast cancer.

Epigenetic Regulation of the Epithelial to Mesenchymal Transition in Lung Cancer

Lung cancer is the leading cause of cancer deaths worldwide. It is an aggressive and devastating cancer because of metastasis triggered by enhanced migration and invasion, and resistance to cytotoxic chemotherapy. The epithelial to mesenchymal transition (EMT) is a fundamental developmental process that is reactivated in wound healing and a variety of diseases including cancer where it promotes migration/invasion and metastasis, resistance to treatment, and generation and maintenance of cancer stem cells. The induction of EMT is associated with reprogramming of the epigenome. This review focuses on major mechanisms of epigenetic regulation mainly in lung cancer with recent data on EZH2 (enhancer of zeste 2 polycomb repressive complex 2 subunit ), the catalytic subunit of the PRC2 (Polycomb Group PcG), that behaves as an oncogene in lung cancer associated with gene repression, non-coding RNAs and the epitranscriptome.

The neuropilin 2 isoform NRP2b uniquely supports TGFβ-mediated progression in lung cancer

Neuropilins (NRP1 and NRP2) are co-receptors for heparin-binding growth factors and class 3 semaphorins. Different isoforms of NRP1 and NRP2 are produced by alternative splicing. We found that in non-small cell lung cancer (NSCLC) cell lines, transforming growth factor-β (TGFβ) signaling preferentially increased the abundance of NRP2b. NRP2b and NRP2a differ only in their carboxyl-terminal regions. Although the presence of NRP2b inhibited cultured cell proliferation and primary tumor growth, NRP2b enhanced cellular migration, invasion into Matrigel, and tumorsphere formation in cultured cells in response to TGFβ signaling and promoted metastasis in xenograft mouse models. These effects of overexpressed NRP2b contrast with the effects of overexpressed NRP2a. Hepatocyte growth factor (HGF)-induced phosphorylation of the kinase AKT was specifically promoted by NRP2b, whereas inhibiting the HGF receptor MET attenuated NRP2b-dependent cell migration. Unlike NRP2a, NRP2b did not bind the PDZ domain scaffolding protein GAIP carboxyl terminus-interacting protein (GIPC1) and only weakly recruited phosphatase and tensin homolog (PTEN), potentially explaining the difference between NRP2b-mediated and NRP2a-mediated effects. Analysis of NSCLC patient tumors showed that NRP2b abundance correlated with that of the immune cell checkpoint receptor ligand PD-L1 as well as with epithelial-to-mesenchymal transition (EMT) phenotypes in the tumors, acquired resistance to epidermal growth factor receptor (EGFR) inhibitors, disease progression, and poor survival in patients. NRP2b knockdown attenuated the acquisition of resistance to the EGFR inhibitor gefitinib in cultured NSCLC cells. Thus, in NSCLC, NRP2b contributed to the oncogenic response to TGFβ and correlated with tumor progression in patients.

ZEB1 Mediates Acquired Resistance to the Epidermal Growth Factor Receptor-Tyrosine Kinase Inhibitors in Non-Small Cell Lung Cancer

Epithelial-mesenchymal transition (EMT) is one mechanism of acquired resistance to inhibitors of the epidermal growth factor receptor-tyrosine kinases (EGFR-TKIs) in non-small cell lung cancer (NSCLC). The precise mechanisms of EMT-related acquired resistance to EGFR-TKIs in NSCLC remain unclear. We generated erlotinib-resistant HCC4006 cells (HCC4006ER) by chronic exposure of EGFR-mutant HCC4006 cells to increasing concentrations of erlotinib. HCC4006ER cells acquired an EMT phenotype and activation of the TGF-β/SMAD pathway, while lacking both T790M secondary EGFR mutation and MET gene amplification. We employed gene expression microarrays in HCC4006 and HCC4006ER cells to better understand the mechanism of acquired EGFR-TKI resistance with EMT. At the mRNA level, ZEB1 (TCF8), a known regulator of EMT, was >20-fold higher in HCC4006ER cells than in HCC4006 cells, and increased ZEB1 protein level was also detected. Furthermore, numerous ZEB1 responsive genes, such as CDH1 (E-cadherin), ST14, and vimentin, were coordinately regulated along with increased ZEB1 in HCC4006ER cells. We also identified ZEB1 overexpression and an EMT phenotype in several NSCLC cells and human NSCLC samples with acquired EGFR-TKI resistance. Short-interfering RNA against ZEB1 reversed the EMT phenotype and, importantly, restored erlotinib sensitivity in HCC4006ER cells. The level of micro-RNA-200c, which can negatively regulate ZEB1, was significantly reduced in HCC4006ER cells. Our results suggest that increased ZEB1 can drive EMT-related acquired resistance to EGFR-TKIs in NSCLC. Attempts should be made to explore targeting ZEB1 to resensitize TKI-resistant tumors.

The emerging role of class-3 semaphorins and their neuropilin receptors in oncology

The semaphorins, discovered over 20 years ago, are a large family of secreted or transmembrane and glycophosphatidylinositol -anchored proteins initially identified as axon guidance molecules crucial for the development of the nervous system. It has now been established that they also play important roles in organ development and function, especially involving the immune, respiratory, and cardiovascular systems, and in pathological disorders, including cancer. During tumor progression, semaphorins can have both pro- and anti-tumor functions, and this has created complexities in our understanding of these systems. Semaphorins may affect tumor growth and metastases by directly targeting tumor cells, as well as indirectly by interacting with and influencing cells from the micro-environment and vasculature. Mechanistically, semaphorins, through binding to their receptors, neuropilins and plexins, affect pathways involved in cell adhesion, migration, invasion, proliferation, and survival. Importantly, neuropilins also act as co-receptors for several growth factors and enhance their signaling activities, while class 3 semaphorins may interfere with this. In this review, we focus on the secreted class 3 semaphorins and their neuropilin co-receptors in cancer, including aspects of their signaling that may be clinically relevant.

Analysis of the t(3;8) of hereditary renal cell carcinoma: a palindrome-mediated translocation

It has emerged that palindrome-mediated genomic instability generates DNA-based rearrangements. The presence of palindromic AT-rich repeats (PATRRs) at the translocation breakpoints suggested a palindrome-mediated mechanism in the generation of several recurrent constitutional rearrangements: the t(11;22), t(17;22), and t(8;22). To date, all reported PATRR-mediated translocations include the PATRR on chromosome 22 (PATRR22) as a translocation partner. Here, the constitutional rearrangement, t(3;8)(p14.2;q24.1), segregating with renal cell carcinoma in two families, is examined. The chromosome 8 breakpoint lies in PATRR8 in the first intron of the RNF139 (TRC8) gene, whereas the chromosome 3 breakpoint is located in an AT-rich palindromic sequence in intron 3 of the FHIT gene (PATRR3). Thus, the t(3;8) is the first PATRR-mediated, recurrent, constitutional translocation that does not involve PATRR22. Furthermore, we detect de novo translocations similar to the t(11;22) and t(8;22), involving PATRR3 in normal sperm. The breakpoint on chromosome 3 is in proximity to FRA3B, the most common fragile site in the human genome and a site of frequent deletions in tumor cells. However, the lack of involvement of PATRR3 sequence in numerous FRA3B-related deletions suggests that there are several different DNA sequence-based etiologies responsible for chromosome 3p14.2 genomic rearrangements.

Neuropilin-2 Is upregulated in lung cancer cells during TGF-β1-induced epithelial-mesenchymal transition

The epithelial-mesenchymal transition (EMT) and its reversal, mesenchymal-epithelial transition (MET), are fundamental processes involved in tumor cell invasion and metastasis. SEMA3F is a secreted semaphorin and tumor suppressor downregulated by TGF-β1 and ZEB1-induced EMT. Here, we report that neuropilin (NRP)-2, the high-affinity receptor for SEMA3F and a coreceptor for certain growth factors, is upregulated during TGF-β1-driven EMT in lung cancer cells. Mechanistically, NRP2 upregulation was TβRI dependent and SMAD independent, occurring mainly at a posttranscriptional level involving increased association of mRNA with polyribosomes. Extracellular signal-regulated kinase (ERK) and AKT inhibition blocked NRP2 upregulation, whereas RNA interference-mediated attenuation of ZEB1 reduced steady-state NRP2 levels. In addition, NRP2 attenuation inhibited TGF-β1-driven morphologic transformation, migration/invasion, ERK activation, growth suppression, and changes in gene expression. In a mouse xenograft model of lung cancer, NRP2 attenuation also inhibited locally invasive features of the tumor and reversed TGF-β1-mediated growth inhibition. In support of these results, human lung cancer specimens with the highest NRP2 expression were predominantly E-cadherin negative. Furthermore, the presence of NRP2 staining strengthened the association of E-cadherin loss with high-grade tumors. Together, our results demonstrate that NRP2 contributes significantly to TGF-β1-induced EMT in lung cancer.

Abstract 274: Neuropilin-2 is upregulated during EMT in lung cancer

Neuropilins (NRP1 and NRP2) are high affinity receptors for the class-3 semaphorins, cell guidance molecules involved in tissue development, immune responses, angiogenesis and cancer. Semaphorins can inhibit proliferation, affect cell protrusion, spreading and adhesion, and trigger migratory responses often in a repulsive manner depending on the cellular context.However, neuropilins can also serve as receptors for galectin-1 and growth promoting factors including VEGF, PlGF, EGF and TGFβ.

We previously cloned the SEMA3F gene from chromosome 3p21.3, which undergoes homozygous deletion and frequent loss of heterozygosity in lung cancer. We found that SEMA3F levels were inversely correlated with tumor aggressiveness in human lung cancer and confirmed its tumor suppressor activity in experimental xenograft models. We subsequently discovered that SEMA3F is directly downregulated by ZEB1, a transcription factor involved in the epithelial to mesenchymal transition (EMT). In the present study, we asked whether NRP2, the SEMA3F-specific receptor, was also regulated during the EMT process.TGFβ, a physiologic EMT inducer, rapidly increased NRP2 expression in NSCLC cell lines. Mechanistically, this increase resulted primarily from enhanced translation with some contribution from increased mRNA levels. However, TGFβ did not stabilize NRP2 mRNA or protein. Furthermore, we found out that a substantial amount of protein at the cell surface directly depended on the presence of TGFβ in the tumor microenvironment. The pathways regulating NRP2 induction include ERK1/2 and Akt but are Smad independent. In addition, forced expression of ZEB1 also induced NRP2. Conversely, ZEB1 inhibition reduced NRP2 upregulation by TGFβ. Importantly, inhibiting NRP2 affected TGFβ-induced morphologic changes, migration and ERK1/2 activation. Interestingly, some EMT target genes were also affected by NRP2 knockdown. Preliminary data in xenograft models indicate that NRP2 inhibition counteracts tumor growth-promoting effects of TGFβ .In a lung tumor tissue microarray, we observed that higher tumor grades were characterized by positive staining for NRP2 and negative staining for E-cadherin while lower tumor grades often presented the opposite profile. Since NRP2 is the highest affinity receptor for SEMA3F, our results suggest that loss of SEMA3F coupled with increased NRP2 would facilitate the binding of growth factors to NRP2 to further promote EMT and metastasis. Therefore, targeting NRP2 could be an important therapeutic approach against EMT in lung cancer.

Citation Format: Patrick Nasarre, Joelle Roche, Vincent A. Potiron, Joyce Nair-Menon, Robert M. Gemmill, Harry A. Drabkin. Neuropilin-2 is upregulated during EMT in 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 274. doi:10.1158/1538-7445.AM2013-274

Abstract 735: Photonic crystal microarray sensing of biomolecules: Detection of ZEB1 associated with the epithelial-mesenchymal transition in lung cancer cells

We experimentally demonstrate the ability of Photonic Crystal microcavity-based biosensors to specifically detect the EMT transcription factor, ZEB1, in minute volumes of sample. Two-dimensional Photonic Crystals manufactured from silicon-on-insulator (SOI) have recently demonstrated the ability to confine and guide slow light on length scales of the wavelength of light. This has led to high sensitivity as well as miniaturization into compact sensors for chemical and bio-sensing. The precise wavelength of infrared light trapped by the resonance cavity of a Photonic Crystal is influenced in a very sensitive fashion by binding interactions between biomolecules attached to the silicon surface. In essence, the binding interaction alters the refractive index of the resonance cavity and this is detected as a shift in the resonance wavelength trapped by the device. When the sensor surface is derivatized with a specific antibody, the binding of the corresponding antigen will generate a resonance shift, revealing the presence of the antigen even when the antigen is present as a minor component in a complex whole-cell lysate. The resonance shift is detected directly and does not require any secondary labeling. The sensor cavity used here is dimensionally comparable to a mitochondrion, having a surface area of ∼5-10 μm2 which contacts approximately 13 nL of sample. The device was able to reliably detect ZEB1 binding in diluted samples of NCI-H358 non-small cell lung cancer cells containing ∼10 cells/μL. Specificity was demonstrated using a sandwich assay in which a second antibody was introduced following the initial binding and washing steps. The resonance wavelength was then super-shifted, but only when the second reagent applied was a different ZEB1-specific antibody that recognized a distinct epitope. These Photonic Crystal waveguides can be multiplexed on a single chip yielding a useful platform for highly sensitive and rapid detection of several biomolecules simultaneously in minute samples. Moreover, the sandwich assay principle can be applied to interrogate post-translational modifications of the captured proteins, so long as site-specific antibodies are available. The Photonic Crystal biosensor should be applicable to biomarker detection in minute biopsies, monitoring of pathway activation states in small samples, and detection of fusion or mutant proteins in hematological malignancies and solid tumors.

Citation Format: Swapnajit Chakravarty, Wei-Cheng Lai, Yi Zou, Harry A. Drabkin, George R. Simon, Steve H. Chin, Ray T. Chen, Robert M. Gemmill. Photonic crystal microarray sensing of biomolecules: Detection of ZEB1 associated with the epithelial-mesenchymal transition in lung cancer cells. [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 735. doi:10.1158/1538-7445.AM2013-735

Phase 1 clinical trial of the novel proteasome inhibitor marizomib with the histone deacetylase inhibitor vorinostat in patients with melanoma, pancreatic and lung cancer based on in vitro assessments of the combination

PURPOSE

Combining proteasome and histone deacetylase (HDAC) inhibition has been seen to provide synergistic anti-tumor activity, with complementary effects on a number of signaling pathways. The novel bi-cyclic structure of marizomib with its unique proteasome inhibition, toxicology and efficacy profiles, suggested utility in combining it with an HDAC inhibitor such as vorinostat. Thus, in this study in vitro studies assessed the potential utility of combining marizomib and vorinostat, followed by a clinical trial with the objectives of assessing the recommended phase 2 dose (RP2D), pharmacokinetics (PK), pharmacodynamics (PD), safety and preliminary anti-tumor activity of the combination in patients.

EXPERIMENTAL DESIGN

Combinations of marizomib and vorinostat were assessed in vitro. Subsequently, in a Phase 1 clinical trial patients with melanoma, pancreatic carcinoma or Non-small Cell Lung Cancer (NSCLC) were given escalating doses of weekly marizomib in combination with vorinostat 300 mg daily for 16 days in 28 day cycles. In addition to standard safety studies, proteasome inhibition and pharmacokinetics were assayed.

RESULTS

Marked synergy of marizomib and vorinostat was seen in tumor cell lines derived from patients with NSCLC, melanoma and pancreatic carcinoma. In the clinical trial, 22 patients were enrolled. Increased toxicity was not seen with the combination. Co-administration did not appear to affect the PK or PD of either drug in comparison to historical data. Although no responses were demonstrated using RECIST criteria, 61% of evaluable patients demonstrated stable disease with 39% having decreases in tumor measurements.

CONCLUSIONS

Treatment of multiple tumor cell lines with marizomib and vorinostat resulted in a highly synergistic antitumor activity. The combination of full dose marizomib with vorinostat is tolerable in patients with safety findings consistent with either drug alone.

Multiplexed specific label-free detection of NCI-H358 lung cancer cell line lysates with silicon based photonic crystal microcavity biosensors

We experimentally demonstrate label-free photonic crystal (PC) microcavity biosensors in silicon-on-insulator (SOI) to detect the epithelial-mesenchymal transition (EMT) transcription factor, ZEB1, in minute volumes of sample. Multiplexed specific detection of ZEB1 in lysates from NCI-H358 lung cancer cells down to an estimated concentration of 2 cells per micro-liter is demonstrated. L13 photonic crystal microcavities, coupled to W1 photonic crystal waveguides, are employed in which resonances show high Q in the bio-ambient phosphate buffered saline (PBS). When the sensor surface is derivatized with a specific antibody, the binding of the corresponding antigen from a complex whole-cell lysate generates a change in refractive index in the vicinity of the photonic crystal microcavity, leading to a change in the resonance wavelength of the resonance modes of the photonic crystal microcavity. The shift in the resonance wavelength reveals the presence of the antigen. The sensor cavity has a surface area of ∼11μm(2). Multiplexed sensors permit simultaneous detection of many binding interactions with specific immobilized antibodies from the same bio-sample at the same instant of time. Specificity was demonstrated using a sandwich assay which further amplifies the detection sensitivity at low concentrations. The device represents a proof-of-concept demonstration of label-free, high throughput, multiplexed detection of cancer cells with specificity and sensitivity on a silicon chip platform.

Cholesterol and the development of clear-cell renal carcinoma

The majority of kidney cancers are clear-cell carcinomas (ccRCC), characterized by the accumulation of cholesterol, cholesterol esters, other neutral lipids and glycogen. Rather than being a passive bystander, the clear-cell phenotype is suggested to be a biomarker of deregulated cholesterol and lipid biosynthesis, which plays an important role in development of the disease. One clue to this relationship has come from the elucidation of the hereditary kidney cancer gene, TRC8, which functions partly to degrade key regulators of endogenous cholesterol and lipid biosynthesis. In addition, deregulation of the mevalonate pathway has been shown to play a key role in cellular transformation and invasion. These findings are supported by considerable epidemiologic data linking obesity and the deregulation of lipid biosynthesis to ccRCC.

Abstract 2416: Neuropilin-2 is upregulated during EMT in lung cancer

Neuropilins (NRP1 and NRP2) are high affinity receptors for the class-3 semaphorins, cell guidance molecules involved in tissue development, immune responses, angiogenesis and cancer. Semaphorins affect cell protrusion, spreading and adhesion, and can trigger migratory responses often in a repulsive manner depending on the cellular context. Interestingly, neuropilins are also receptors for galectin-1 and growth factors including VEGF, PlGF, EGF and TGFβ. We previously cloned the SEMA3F gene from chromosome 3p21.3, which undergoes homozygous deletion and frequent loss of heterozygosity in lung cancer. We found that SEMA3F levels were inversely correlated with tumor aggressiveness in human lung cancer and confirmed its tumor suppressor activity in experimental xenograft models. We subsequently discovered that SEMA3F is directly downregulated by ZEB1, a transcription factor involved in the epithelial to mesenchymal transition (EMT). In the present study, we asked whether SEMA3F specific receptor, NRP2, was also regulated during the EMT process. TGFβ, a physiologic EMT inducer, stimulated NRP2 expression in two NSCLC cell lines. Forced expression of ZEB1, but not Snail, also induced NRP2. Conversely, ZEB1 and Snail inhibition blocked NRP2 upregulation by TGFβ. Importantly, inhibiting NRP2 or ZEB1 expression reduced TGFβ-induced migration in an equivalent manner. In lung cancer tissue microarrays, NRP1 and NRP2 were preferentially expressed in the tumor compartment, whereas the EMT-related transcription factors, ZEB1 and Snail, were predominantly expressed in the stroma. Of note, NRP2 was also expressed in stromal cells and was significantly associated with both ZEB1 and a higher (worse) tumor grade. Since NRP2 is the highest affinity receptor for SEMA3F, our results suggest that loss of SEMA3F coupled with increased NRP2 would facilitate the binding of growth factors to NRP2 to further promote EMT and metastasis. Therefore, targeting NRP2 could be an important therapeutic approach against EMT in lung cancer.

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 2416. doi:1538-7445.AM2012-2416

Gene expression profiling identifies inflammation and angiogenesis as distinguishing features of canine hemangiosarcoma

Background

The etiology of hemangiosarcoma remains incompletely understood. Its common occurrence in dogs suggests predisposing factors favor its development in this species. These factors could represent a constellation of heritable characteristics that promote transformation events and/or facilitate the establishment of a microenvironment that is conducive for survival of malignant blood vessel-forming cells. The hypothesis for this study was that characteristic molecular features distinguish hemangiosarcoma from non-malignant endothelial cells, and that such features are informative for the etiology of this disease.

Methods

We first investigated mutations of VHL and Ras family genes that might drive hemangiosarcoma by sequencing tumor DNA and mRNA (cDNA). Protein expression was examined using immunostaining. Next, we evaluated genome-wide gene expression profiling using the Affymetrix Canine 2.0 platform as a global approach to test the hypothesis. Data were evaluated using routine bioinformatics and validation was done using quantitative real time RT-PCR.

Results

Each of 10 tumor and four non-tumor samples analyzed had wild type sequences for these genes. At the genome wide level, hemangiosarcoma cells clustered separately from non-malignant endothelial cells based on a robust signature that included genes involved in inflammation, angiogenesis, adhesion, invasion, metabolism, cell cycle, signaling, and patterning. This signature did not simply reflect a cancer-associated angiogenic phenotype, as it also distinguished hemangiosarcoma from non-endothelial, moderately to highly angiogenic bone marrow-derived tumors (lymphoma, leukemia, osteosarcoma).

Conclusions

The data show that inflammation and angiogenesis are important processes in the pathogenesis of vascular tumors, but a definitive ontogeny of the cells that give rise to these tumors remains to be established. The data do not yet distinguish whether functional or ontogenetic plasticity creates this phenotype, although they suggest that cells which give rise to hemangiosarcoma modulate their microenvironment to promote tumor growth and survival. We propose that the frequent occurrence of canine hemangiosarcoma in defined dog breeds, as well as its similarity to homologous tumors in humans, offers unique models to solve the dilemma of stem cell plasticity and whether angiogenic endothelial cells and hematopoietic cells originate from a single cell or from distinct progenitor cells.

ZEB1-responsive genes in non-small cell lung cancer

The epithelial to mesenchymal transition (EMT) is a developmental process enabling epithelial cells to gain a migratory mesenchymal phenotype. In cancer, this process contributes to metastases; however the regulatory signals and mechanistic details are not fully elucidated. Here, we sought to identify the subset of genes regulated in lung cancer by ZEB1, an E-box transcriptional repressor known to induce EMT. Using an Affymetrix-based expression database of 38 non-small cell lung cancer (NSCLC) cell lines, we identified 324 genes that correlated negatively with ZEB1 and 142 that were positively correlated. A mesenchymal gene pattern (low E-cadherin, high Vimentin or N-cadherin) was significantly associated with ZEB1 and ZEB2, but not with Snail, Slug, Twist1 or Twist2. Among eight genes selected for validation, seven were confirmed to correlate with ZEB1 by quantitative real-time RT-PCR in a series of 22 NSCLC cell lines, either negatively (CDS1, EpCAM, ESRP1, ESRP2, ST14) or positively (FGFR1, Vimentin). In addition, over-expression or knockdown of ZEB1 led to corresponding changes in gene expression, demonstrating that these genes are also regulated by ZEB1, either directly or indirectly. Of note, the combined knockdown of ZEB1 and ZEB2 led to apparent synergistic responses in gene expression. Furthermore, these responses were not restricted to artificial settings, since most genes were similarly regulated during a physiologic induction of EMT by TGF-β plus EGF. Finally, the absence of ST14 (matriptase) was linked to ZEB1 positivity in lung cancer tissue microarrays, implying that the regulation observed in vitro applies to the human disease. In summary, this study identifies a new set of ZEB-regulated genes in human lung cancer cells and supports the hypothesis that ZEB1 and ZEB2 are key regulators of the EMT process in this disease.

A palindrome-mediated recurrent translocation with 3:1 meiotic nondisjunction: the t(8;22)(q24.13;q11.21)

Palindrome-mediated genomic instability has been associated with chromosomal translocations, including the recurrent t(11;22)(q23;q11). We report a syndrome characterized by extremity anomalies, mild dysmorphia, and intellectual impairment caused by 3:1 meiotic segregation of a previously unrecognized recurrent palindrome-mediated rearrangement, the t(8;22)(q24.13;q11.21). There are at least ten prior reports of this translocation, and nearly identical PATRR8 and PATRR22 breakpoints were validated in several of these published cases. PCR analysis of sperm DNA from healthy males indicates that the t(8;22) arises de novo during gametogenesis in some, but not all, individuals. Furthermore, demonstration that de novo PATRR8-to-PATRR11 translocations occur in sperm suggests that palindrome-mediated translocation is a universal mechanism producing chromosomal rearrangements.

Obesity, cholesterol, and clear-cell renal cell carcinoma (RCC)

Multiple epidemiologic studies have linked the development of renal cancer to obesity. In this chapter, we begin with a review of selected population studies, followed by recent mechanistic discoveries that further link lipid deregulation to the RCC development. The upregulation of leptin and downregulation of adiponectin pathways in obesity fit well with our molecular understanding of RCC pathogenesis. In addition, two forms of hereditary RCC involve proteins, Folliculin and TRC8, that are positioned to coordinately regulate lipid and protein biosynthesis. Both of these biosynthetic pathways have important downstream consequences on HIF-1/2alpha levels and angiogenesis, key aspects in the disease pathogenesis. The role of lipid biology and its interface with protein translation regulation represents a new dimension in RCC research with potential therapeutic implications.

The TRC8 ubiquitin ligase is sterol regulated and interacts with lipid and protein biosynthetic pathways

TRC8/RNF139 encodes an endoplasmic reticulum-resident E3 ubiquitin ligase that inhibits growth in a RING- and ubiquitylation-dependent manner. TRC8 also contains a predicted sterol-sensing domain. Here, we report that TRC8 protein levels are sterol responsive and that it binds and stimulates ubiquitylation of the endoplasmic reticulum anchor protein INSIG. Induction of TRC8 destabilized the precursor forms of the transcription factors SREBP-1 and SREBP-2. Loss of SREBP precursors was proteasome dependent, required a functional RING domain, occurred without generating processed nuclear forms, and suppressed SREBP target genes. TRC8 knockdown had opposite effects in sterol-deprived cells. In Drosophila, growth inhibition by DTrc8 was genetically suppressed by loss of specific Mprlp, Padlp N-terminal domain-containing proteins found in the COP9 signalosome and eIF3. DTrc8 genetically and physically interacted with two eIF3 subunits: eIF3f and eIF3h. Coimmunoprecipitation experiments confirmed these interactions in mammalian cells, and TRC8 overexpression suppressed polysome profiles. Moreover, high-molecular weight ubiquitylated proteins were observed in eIF3 immunoprecipitations from TRC8-overexpressing cells. Thus, TRC8 function may provide a regulatory link between the lipid and protein biosynthetic pathways.

The TRC8 E3 ligase ubiquitinates MHC class I molecules before dislocation from the ER

Human cytomegalovirus uses an E3 ubiquitin ligase to divert MHC I molecules into the ER-associated degradation pathway for destruction.

The US2 and US11 gene products of human cytomegalovirus promote viral evasion by hijacking the endoplasmic reticulum (ER)–associated degradation (ERAD) pathway. US2 and US11 initiate dislocation of newly translocated major histocompatibility complex class I (MHC I) from the ER to the cytosol for proteasome-mediated degradation, thereby decreasing cell surface MHC I. Despite being instrumental in elucidating the mammalian ERAD pathway, the responsible E3 ligase or ligases remain unknown. Using a functional small interfering RNA library screen, we now identify TRC8 (translocation in renal carcinoma, chromosome 8 gene), an ER-resident E3 ligase previously implicated as a hereditary kidney cancer gene, as required for US2-mediated MHC I ubiquitination. Depletion of TRC8 prevents MHC I ubiquitination and dislocation by US2 and restores cell surface MHC I. TRC8 forms an integral part of a novel multiprotein ER complex that contains MHC I, US2, and signal peptide peptidase. Our data show that the TRC8 E3 ligase is required for MHC I dislocation from the ER and identify a new complex associated with mammalian ERAD.

The tumor suppressor gene TRC8/RNF139 is disrupted by a constitutional balanced translocation t(8;22)(q24.13;q11.21) in a young girl with dysgerminoma

Background

RNF139/TRC8 is a potential tumor suppressor gene with similarity to PTCH, a tumor suppressor implicated in basal cell carcinomas and glioblastomas. TRC8 has the potential to act in a novel regulatory relationship linking the cholesterol/lipid biosynthetic pathway with cellular growth control and has been identified in families with hereditary renal (RCC) and thyroid cancers. Haploinsufficiency of TRC8 may facilitate development of clear cell-RCC in association with VHL mutations, and may increase risk for other tumor types. We report a paternally inherited balanced translocation t(8;22) in a proposita with dysgerminoma.

Methods

The translocation was characterized by FISH and the breakpoints cloned, sequenced, and compared. DNA isolated from normal and tumor cells was checked for abnormalities by array-CGH. Expression of genes TRC8 and TSN was tested both on dysgerminoma and in the proposita and her father.

Results

The breakpoints of the translocation are located within the LCR-B low copy repeat on chromosome 22q11.21, containing the palindromic AT-rich repeat (PATRR) involved in recurrent and non-recurrent translocations, and in an AT-rich sequence inside intron 1 of the TRC8 tumor-suppressor gene at 8q24.13. TRC8 was strongly underexpressed in the dysgerminoma. Translin is underexpressed in the dysgerminoma compared to normal ovary.

TRC8 is a target of Translin (TSN), a posttranscriptional regulator of genes transcribed by the transcription factor CREM-tau in postmeiotic male germ cells.

Conclusion

A role for TRC8 in dysgerminoma may relate to its interaction with Translin. We propose a model in which one copy of TRC8 is disrupted by a palindrome-mediated translocation followed by complete loss of expression through suppression, possibly mediated by miRNA.

Pulsed-field gel electrophoresis for long-range restriction mapping

This unit describes procedures for generating long-range restriction maps of genomic DNA and for analysis of large insert clones. The basic protocol details restriction digestion of agarose-embedded DNA, PFGE separation, Southern transfer, and hybridization. Support protocols describe the preparation of high-molecular-weight genomic DNA samples in agarose blocks and in agarose microbeads, respectively. Additional support protocols describe the preparation of DNA size standards from l phage and two yeast species, Saccharomyces cerevisiae and Schizosaccharomyces pombe. An alternative method of preparing S. cerevisiae size standards using lithium dodecyl sulfate (LiDS) solubilization is provided. The final protocol details the preparation of BAC DNA suitable for digestion, mapping, and sequencing.

Purification and characterization of YACs containing large inserts

This unit provides protocols for characterizing DNA segments cloned in YACs and for purifying YACs from yeast chromosomes. The first basic protocol describes Southern blotting and partial-digest restriction analysis of YACs. These methods are useful for determining the size and complexity of the cloned insert DNA, the presence and location of particular restriction sites or sequences, and even the species of origin of the insert DNA (indicated by hybridization to species-specific repetitive elements such as Alu repeats). The second basic protocol describes gel purification of YACs for use in procedures requiring pure YAC DNA, such as mammalian-cell transformation and subcloning into smaller insert vectors. The third basic protocol details characterizing and analyzing YACs: in vivo fragmentation via homologous recombination with specialized fragmentation vectors containing specific probe sequences or repetitive elements, followed by Southern blotting with YAC- and human-derived probes.

A constitutional balanced t(3;8)(p14;q24.1) translocation results in disruption of the TRC8 gene and predisposition to clear cell renal cell carcinoma

Studying the molecular basis of familial renal cell carcinoma (RCC) has allowed identification of novel RCC genes involved in the pathogenesis of both inherited and sporadic RCC. We describe a constitutional balanced t(3;8)(p14;q24.1) translocation found in a brother and sister with bilateral clear cell RCC (CC-RCC) diagnosed in their forties. Consistent with a prior report, we demonstrated by RT-PCR of RNA from lymphoblastoid cells fusion mRNAs derived from the fragile histidine triad (FHIT) at 3p14 and TRC8 at 8q24.1 in both affected siblings. Cytogenetic analysis of a CC-RCC tumor from the affected sister from short-term tumor cell culture showed both diploid and pseudotetraploid populations containing the translocation and normal appearing chromosomes 3 and 8. Fluorescent in situ hybridization using bacterial artificial chromosomes containing sequences from the FHIT and TRC8 genes demonstrated normal FHIT signals and TRC8 signals on nontranslocated chromosomes in the constitutional blood sample, but the TRC8 signal was absent in a subset of diploid and pseudotetraploid cells from the tumor. The tumor also contained a heterozygous VHL frameshift somatic mutation. These results confirm that balanced translocations disrupting the TRC8 and FHIT genes result in an increased genetic susceptibility for bilateral CC-RCC. The presence of diploid and tetraploid tumor cells with and without TRC8 deletions on the nontranslocated chromosome suggest that loss of the remaining normal allele of TRC8 may contribute to tumor development at later stages.

Semaphorin SEMA3F Affects Multiple Signaling Pathways in Lung Cancer Cells

Loss of SEMA3F occurs frequently in lung cancer and correlates with advanced stage of disease. We previously reported that SEMA3F blocked tumor formation by H157 lung cancer cells in a rat orthotopic model. This was associated with loss of activated alpha(V)beta(3) integrin, impaired cell adhesion to extracellular matrix components, and down-regulation of phospho-extracellular signal-regulated kinase 1/2 (ERK1/2). These results suggested that SEMA3F might interfere with integrin outside-in signaling. In the present report, we found that SEMA3F decreased adhesion to vitronectin, whereas integrin-linked kinase (ILK) kinase activity was down-regulated in SEMA3F-expressing H157 cells. Exposure to SEMA3F-conditioned medium led to diminution of phospho-ERK1/2 in four of eight lung cancer cell lines, and ILK silencing by small interfering RNA led to similar loss of phospho-ERK1/2 in H157 cells. Moreover, SEMA3F expression (with constitutive and inducible systems) also reduced AKT and signal transducer and activator of transcription 3 (STAT3) phosphorylation independently of ILK-ERK1/2. These signaling changes extended downstream to hypoxia-inducible factor-1alpha (HIF-1alpha) protein and vascular endothelial growth factor (VEGF) mRNA levels, which were both reduced in three of four SEMA3F-transfected cell lines. Mechanistically, the effects on HIF-1alpha were consistent with inhibition of its AKT-driven protein translation initiation, with no effect on HIF-1alpha mRNA level or protein degradation. Furthermore, when H157 cells were injected s.c. in nude mice, tumors derived from SEMA3F-expressing cells showed lower microvessel density and tumor growth. These results show that SEMA3F negatively affects ILK-ERK1/2 and AKT-STAT3 signaling, along with inhibition of HIF-1alpha and VEGF. These changes would be anticipated to contribute significantly to the observed antitumor activity of SEMA3F.

Upstream signaling inhibition enhances rapamycin effect on growth of kidney cancer cells

OBJECTIVES

To test the hypothesis that blockage of epidermal growth factor receptor (EGFR) or methylethylketone (MEK)1/2 kinase activities impairs the growth of kidney cancer cells and magnifies the growth inhibitory effect of the mammalian target of rapamycin (mTOR) inhibitor rapamycin.

METHODS

The kidney cancer cells from eight cell lines (including a pair in which the VHL gene or an empty vector was transfected in a VHL(mut) cell line) were tested for the effect of treatment with an EGFR inhibitor or an MEK1/2 inhibitor on the phosphorylation status of the phosphatidyl inositol 3-OH kinase (PI3K) and mitogen-activated protein kinase (MAPK) pathways after stimulation with EGF. In vitro growth assays were performed with EGFR inhibitors (gefitinib or erlotinib) or with MEK1/2 inhibitors (UO126 or PD184352) alone or in combination with rapamycin. The effects of PD184352, rapamycin, and their combination in the cell cycle were evaluated by flow cytometry.

RESULTS

The growth suppressive effect of combined gefitinib (or erlotinib) and rapamycin was greater than the effect of each drug alone and was not dependent on VHL status. By affecting downstream signaling, the MEK1/2 inhibitors U0126 and PD184352 blocked growth more effectively than did the EGFR inhibitors in selected renal cell carcinoma lines; this effect was enhanced by the addition of rapamycin. At the cell cycle level, the combination resulted in enhanced G1 arrest. Although eIF4E overexpression has been suggested to make cells resistant to rapamycin, we observed marked growth inhibition with rapamycin as a single agent in SKRC39, which has marked overexpression of eIF4E.

CONCLUSIONS

The results of our study have shown that combined mTOR and other upstream inhibitors have strong potential in the treatment of renal cell carcinoma.

RING-dependent tumor suppression and G2/M arrest induced by the TRC8 hereditary kidney cancer gene

TRC8/RNF139 and von Hippel-Lindau (VHL) both encode E3 ubiquitin (Ub) ligases mutated in clear-cell renal carcinomas (ccRCC). VHL, inactivated in nearly 70% of ccRCCs, is a tumor suppressor encoding the targeting subunit for a Ub ligase complex that downregulates hypoxia-inducible factor-alpha. TRC8/RNF139 is a putative tumor suppressor containing a sterol-sensing domain and a RING-H2 motif essential for Ub ligase activity. Here we report that human kidney cells are growth inhibited by TRC8. Inhibition is manifested by G2/M arrest, decreased DNA synthesis and increased apoptosis and is dependent upon the Ub ligase activity of the RING domain. Tumor formation in a nude mouse model is inhibited by TRC8 in a RING-dependent manner. Expression of TRC8 represses genes involved in cholesterol and fatty acid biosynthesis that are transcriptionally regulated by the sterol response element binding proteins (SREBPs). Expression of activated SREBP-1a partially restores the growth of TRC8-inhibited cells. These data suggest that TRC8 modulation of SREBP activity comprises a novel regulatory link between growth control and the cholesterol/lipid homeostasis pathway.

Cyclooxygenase-2-dependent regulation of E-cadherin: prostaglandin E(2) induces transcriptional repressors ZEB1 and snail in non-small cell lung cancer

Elevated tumor cyclooxygenase-2 (COX-2) expression is associated with tumor invasion, metastasis, and poor prognosis in non-small cell lung cancer (NSCLC). Here, we report that COX-2-dependent pathways contribute to the modulation of E-cadherin expression in NSCLC. First, whereas genetically modified COX-2-sense (COX-2-S) NSCLC cells expressed low E-cadherin and showed diminished capacity for cellular aggregation, genetic or pharmacologic inhibition of tumor COX-2 led to increased E-cadherin expression and resulted in augmented homotypic cellular aggregation among NSCLC cells in vitro. An inverse relationship between COX-2 and E-cadherin was shown in situ by double immunohistochemical staining of human lung adenocarcinoma tissue sections. Second, treatment of NSCLC cells with exogenous prostaglandin E(2) (PGE(2)) significantly decreased the expression of E-cadherin, whereas treatment of COX-2-S cells with celecoxib (1 mumol/L) led to increased E-cadherin expression. Third, the transcriptional suppressors of E-cadherin, ZEB1 and Snail, were up-regulated in COX-2-S cells or PGE(2)-treated NSCLC cells but decreased in COX-2-antisense cells. PGE(2) exposure led to enhanced ZEB1 and Snail binding at the chromatin level as determined by chromatin immunoprecipitation assays. Small interfering RNA-mediated knockdown of ZEB1 or Snail interrupted the capacity of PGE(2) to down-regulate E-cadherin. Fourth, an inverse relationship between E-cadherin and ZEB1 and a direct relationship between COX-2 and ZEB1 were shown by immunohistochemical staining of human lung adenocarcinoma tissue sections. These findings indicate that PGE(2), in autocrine or paracrine fashion, modulates transcriptional repressors of E-cadherin and thereby regulates COX-2-dependent E-cadherin expression in NSCLC. Thus, blocking PGE(2) production or activity may contribute to both prevention and treatment of NSCLC.

Restoring E-cadherin expression increases sensitivity to epidermal growth factor receptor inhibitors in lung cancer cell lines

The epidermal growth factor receptor (EGFR) is overexpressed in the majority of non-small cell lung cancers (NSCLC). EGFR tyrosine kinase inhibitors, such as gefitinib and erlotinib, produce 9% to 27% response rates in NSCLC patients. E-Cadherin, a calcium-dependent adhesion molecule, plays an important role in NSCLC prognosis and progression, and interacts with EGFR. The zinc finger transcriptional repressor, ZEB1, inhibits E-cadherin expression by recruiting histone deacetylases (HDAC). We identified a significant correlation between sensitivity to gefitinib and expression of E-cadherin, and ZEB1, suggesting their predictive value for responsiveness to EGFR-tyrosine kinase inhibitors. E-Cadherin transfection into a gefitinib-resistant line increased its sensitivity to gefitinib. Pretreating resistant cell lines with the HDAC inhibitor, MS-275, induced E-cadherin along with EGFR and led to a growth-inhibitory and apoptotic effect of gefitinib similar to that in gefitinib-sensitive NSCLC cell lines including those harboring EGFR mutations. Thus, combined HDAC inhibitor and gefitinib treatment represents a novel pharmacologic strategy for overcoming resistance to EGFR inhibitors in patients with lung cancer.

Selective suppression of in vivo tumorigenicity by semaphorin SEMA3F in lung cancer cells

Loss of the 3p21.3-encoded semaphorins, SEMA3B and SEMA3F, is implicated in lung cancer development. Although both antagonize VEGF binding/response to neuropilin (NRP) receptors, in lung cancer lines, SEMA3F is predominantly expressed and preferentially utilizes NRP2. In lung cancer patients, SEMA3F loss correlates with advanced disease and increased VEGF binding to tumor cells. In cell lines, VEGF enhances adhesion and migration in an integrin-dependent manner, and exogenous SEMA3F causes cells to round and lose extracellular contacts. Using retroviral infections, we established stable SEMA3F transfectants in two NSCLC cell lines, NCI-H157 and NCI-H460. When orthotopically injected into nude rats, both control lines caused lethal tumors in all recipients. In contrast, all animals receiving H157-SEMA3F cells, survived to 100 days, whereas all H157 controls succumbed. In H460 cells, which express NRP1 but not NRP2, SEMA3F did not prolong survival. This antitumor effect in H157 cells was associated with loss of activated alpha(v)beta(3) integrin and adhesion to extracellular matrix components. In addition, H157-SEMA3F cells, and parental H157 cells exposed to SEMA3F-conditioned medium, showed loss of p42/p44 MAPK phosphorylation. Thus, in this in vivo lung cancer model, SEMA3F has potent antitumor effects, which may impinge on activated integrin and MAPK signaling.

Synergistic growth inhibition by Iressa and Rapamycin is modulated by VHL mutations in renal cell carcinoma

Epidermal growth factor receptor (EGFR) and tumour growth factor alpha (TGFα) are frequently overexpressed in renal cell carcinoma (RCC) yet responses to single-agent EGFR inhibitors are uncommon. Although von Hippel–Lindau (VHL) mutations are predominant, RCC also develops in individuals with tuberous sclerosis (TSC). Tuberous sclerosis mutations activate mammalian target of rapamycin (mTOR) and biochemically resemble VHL alterations. We found that RCC cell lines expressed EGFR mRNA in the near-absence of other ErbB family members. Combined EGFR and mTOR inhibition synergistically impaired growth in a VHL-dependent manner. Iressa blocked ERK1/2 phosphorylation specifically in wt-VHL cells, whereas rapamycin inhibited phospho-RPS6 and 4E-BP1 irrespective of VHL. In contrast, phospho-AKT was resistant to these agents and MYC translation initiation (polysome binding) was similarly unaffected unless AKT was inhibited. Primary RCCs vs cell lines contained similar amounts of phospho-ERK1/2, much higher levels of ErbB-3, less phospho-AKT, and no evidence of phospho-RPS6, suggesting that mTOR activity was reduced. A subset of tumours and cell lines expressed elevated eIF4E in the absence of upstream activation. Despite similar amounts of EGFR mRNA, cell lines (vs tumours) overexpressed EGFR protein. In the paired cell lines, PRC3 and WT8, EGFR protein was elevated post-transcriptionally in the VHL mutant and EGF-stimulated phosphorylation was prolonged. We propose that combined EGFR and mTOR inhibitors may be useful in the subset of RCCs with wt-VHL. However, apparent differences between primary tumours and cell lines require further investigation.

Growth suppression induced by the TRC8 hereditary kidney cancer gene is dependent upon JAB1/CSN5

TRC8 encodes an E3-ubiquitin ligase disrupted in a family with hereditary renal cell carcinoma (RCC). We previously reported that Drosophila Trc8 (DTrc8) overexpression inhibits growth and that human and fly proteins interact with with the COP9 signalosome (CSN) subunit JAB1/CSN5. However, further mechanistic evidence linking DTrc8 growth suppression to CSN5 was lacking. Here, we show that haploinsufficiency of CSN5, or a T100I point mutation (CSN5(3)), relieved growth suppression by DTrc8, whereas CSN5(1) (E160V) and CSN5(2) (G147D) mutations had no effect. The strength of yeast two-hybrid interactions between DTrc8 and CSN5 were in complete agreement with the observed phenotypes. DTrc8 overexpression resulted in elevated levels of CSN5 and CSN7, but had no effect on NEDD8-modified Cul-1. In contrast to CSN5, heterozygosity for CSN4null had no effect on the DTrc8 phenotype. We also looked for genetic interactions between DTrc8 and other MPN domain proteins in the CSN and 26S proteasome lid. CSN6 haploinsufficiency restored growth, whereas reduction of proteasome subunits RPN8 or RPN11 had no effect. DTrc8 expression increased the level of digitonin-extractable CSN complex, consistent with elevated levels of CSN5 and 7. Our genetic results confirm that DTrc8-induced growth suppression is CSN5 (and CSN6) dependent. While there was no obvious influence on CSN deneddylation activity, the increase in CSN subunits and holocomplex suggests that TRC8 modulates signalosome levels or compartmentalization.

Hox expression in AML identifies a distinct subset of patients with intermediate cytogenetics

We previously reported that favorable and poor prognostic chromosomal rearrangements in acute myeloid leukemia (AML) were associated with distinct levels of HOX expression. We have now analyzed HOX expression in 50 independent adult AML patients (median age=62 years), together with FLT3 and FLT3-ligand mRNA levels, and FLT3 mutation determination. By cluster analysis, we could divide AMLs into cases with low, intermediate and high HOX expression. Cases with high expression were uniquely restricted to a subset of AMLs with intermediate cytogenetics (P=0.0174). This subset has significantly higher levels of FLT3 expression and appears to have an increase of FLT3 mutations (44%), while CEBPalpha mutations were infrequent (6%). FLT3 mRNA levels were correlated with the expression of multiple HOX genes, whereas FLT3 mutations were correlated with HOXB3. In some cases, FLT3 was expressed at levels equivalent to GAPDH in the absence of genomic amplification. We propose that high HOX expression may be characteristically associated with a distinct biologic subset of AML. The apparent global upregulation of HOX expression could be due to growth-factor signaling or, alternatively, these patterns may reflect a particular stage of differentiation of the leukemic cells.

WNT7a induces E-cadherin in lung cancer cells

E-cadherin loss in cancer is associated with de-differentiation, invasion, and metastasis. Drosophila DE-cadherin is regulated by Wnt/beta-catenin signaling, although this has not been demonstrated in mammalian cells. We previously reported that expression of WNT7a, encoded on 3p25, was frequently downregulated in lung cancer, and that loss of E-cadherin or beta-catenin was a poor prognostic feature. Here we show that WNT7a both activates E-cadherin expression via a beta-catenin specific mechanism in lung cancer cells and is involved in a positive feedback loop. Li+, a GSK3 beta inhibitor, led to E-cadherin induction in an inositol-independent manner. Similarly, exposure to mWNT7a specifically induced free beta-catenin and E-cadherin. Among known transcriptional suppressors of E-cadherin, ZEB1 was uniquely correlated with E-cadherin loss in lung cancer cell lines, and its inhibition by RNA interference resulted in E-cadherin induction. Pharmacologic reversal of E-cadherin and WNT7a losses was achieved with Li+, histone deacetylase inhibition, or in some cases only with combined inhibitors. Our findings provide support that E-cadherin induction by WNT/beta-catenin signaling is an evolutionarily conserved pathway operative in lung cancer cells, and that loss of WNT7a expression may be important in lung cancer development or progression by its effects on E-cadherin.

The TRC8 hereditary kidney cancer gene suppresses growth and functions with VHL in a common pathway

VHL is part of an SCF related E3-ubiquitin ligase complex with 'gatekeeper' function in renal carcinoma. However, no mutations have been identified in VHL interacting proteins in wild type VHL tumors. We previously reported that the TRC8 gene was interrupted by a t(3;8) translocation in a family with hereditary renal and non-medullary thyroid cancer. TRC8 encodes a multi-membrane spanning protein containing a RING-H2 finger with in vitro ubiquitin ligase activity. We isolated the Drosophila homologue, DTrc8, and studied its function by genetic manipulations and a yeast 2-hybrid screen. Human and Drosophila TRC8 proteins localize to the endoplasmic reticulum. Loss of either DTrc8 or DVhl resulted in an identical ventral midline defect. Direct interaction between DTrc8 and DVhl was confirmed by GST-pulldown and co-immunoprecipitation experiments. CSN-5/JAB1 is a component of the COP9 signalosome, recently shown to regulate SCF function. We found that DTrc8 physically interacts with CSN-5 and that human JAB1 localization is dependent on VHL mutant status. Lastly, overexpression of DTrc8 inhibited growth consistent with its presumed role as a tumor suppressor gene. Thus, VHL, TRC8, and JAB1 appear to be linked both physically and functionally and all three may participate in the development of kidney cancer.

High-throughput tissue microarray analysis used to evaluate biology and prognostic significance of the E-cadherin pathway in non-small-cell lung cancer

PURPOSE

E-cadherin (E-cad) and its associated intracellular molecules, catenins, are critical for intercellular epithelial adhesion and are often expressed in non-small-cell lung carcinomas (NSCLCs). We constructed tissue microarrays (TMAs) to investigate the expression of cadherins and catenins and their prognostic significance in NSCLC.

PATIENTS AND METHODS

Tumor tissue samples from 193 patients with stages I to III NSCLC were obtained from the University of Colorado Cancer Center and Johns Hopkins Medical Institutions. Viable tumor was sampled in triplicate for the TMAs, and slides were stained by immunohistochemistry with antibodies against E-cad, N-cadherin, alpha (alpha)-, beta (beta)-, and gamma (gamma)-catenin, p120, p27, and adenomatous polyposis coli (APC) gene product. Clinical data were collected by the tumor registries. Patients were followed for a median period of 51 months (range, 18 to 100 months).

RESULTS

Absent or severely reduced membranous expression for E-cad, alpha-, beta-, and gamma-catenin, and p120 were observed in 10%, 17%, 8%, 31%, and 61% of the cases, respectively. Tumor cell dedifferentiation correlated with reduced expression for E-cad, beta-catenin, gamma-catenin, and p120 in squamous cell carcinomas but not in adenocarcinomas. There was an inverse correlation between nodal metastasis and expression of E-cad and gamma-catenin. Besides the traditional clinical prognostic variables, E-cad and alpha-, beta-, and gamma-catenin expression were of positive prognostic value in univariate survival analyses. In multivariate analysis, E-cad expression was the only independent prognostic factor for survival in addition to age, node status, tumor status, and pathologic surgical margins.

CONCLUSION

Reduced expression of E-cad and catenins is associated with tumor cell dedifferentiation, local invasion, regional metastasis, and reduced survival in NSCLC. E-cad is an independent prognostic factor for NSCLC survival.

Minimal residual disease (MRD) in remission t(8;21) AML and in vivo differentiation detected by FISH and CD34+ cell sorting

Many patients with t(8;21) AML have residual positive cells during remission. We previously developed D-FISH probes that detect both derivative chromosomes and the normal alleles. In negative controls, only 2/44,000 (0.0045%) positive signals were observed. To investigate MRD, we examined specimens from 29 patients who had initially obtained CR. In remission patients, 61% had 1-4/2000 positive cells (0.05-0.19%). Higher frequencies were found in two patients in early relapse and in one patient in early remission. However, a negative test did not exclude relapse. Since false positives were negligible and because most t(8;21) AMLs express CD34, we asked whether cell sorting combined with FISH would increase the sensitivity. In one patient, we observed that 80% of CD34+ cells were t(8;21)+ at 2 months from initial clinical and cytogenetic remission. However, by 5 months the pre- and post-sorted populations contained 0.15% and 0.06% t(8;21) cells, respectively. Whereas essentially all t(8;21) cells in the initial specimen expressed CD34, only 0.6% were subsequently CD34+. These results are consistent with in vitro assays showing that residual t(8;21) cells undergo differentiation. Thus, FISH can identify MRD in a majority of t(8;21) patients and, combined with CD34+ selection, may provide an indirect assessment of the differentiation state of residual t(8;21) cells.

Mutations of the beta- and gamma-catenin genes are uncommon in human lung, breast, kidney, cervical and ovarian carcinomas

Beta-catenin forms complexes with Tcf and Lef-1 and functions as a transcriptional activator in the Wnt signalling pathway. Although recent investigations have been focused on the role of the adenomatous polyposis coli (APC)/ beta-catenin/Tcf pathway in human tumorigenesis, there have been very few reports on mutations of the beta-catenin gene in a variety of tumour types. Using PCR and single-strand conformational polymorphism analysis, we examined 93 lung, 9 breast, 6 kidney, 19 cervical and 7 ovarian carcinoma cell lines for mutations in exon 3 of the beta-catenin gene. In addition, we tested these same samples for mutations in the NH2-terminal regulatory region of the gamma-catenin gene. Mutational analysis for the entire coding region of beta-catenin cDNA was also undertaken in 20 lung, 9 breast, 5 kidney and 6 cervical carcinoma cell lines. Deletion of most beta-catenin coding exons was confirmed in line NCI-H28 (lung mesothelioma) and a silent mutation at codon 214 in exon 5 was found in HeLa (cervical adenocarcinoma). A missense mutation at codon 19 and a silent mutation at codon 28 in the NH2-terminal regulatory region of the gamma-catenin gene were found in H1726 (squamous cell lung carcinoma) and H1048 (small cell lung carcinoma), respectively. Neither deletions nor mutations of these genes were detected in the other cell lines examined. These results suggest that beta- and gamma-catenins are infrequent mutational targets during development of human lung, breast, kidney, cervical and ovarian carcinomas.

Altered HOX and WNT7A expression in human lung cancer

HOX genes encode transcription factors that control patterning and cell fates. Alterations in HOX expression have been clearly implicated in leukemia, but their role in most other malignant diseases remains unknown. By using degenerate reverse transcription-PCR and subsequent real-time quantitative assays, we examined HOX expression in lung cancer cell lines, direct tumor-control pairs, and bronchial epithelial cultures. As in leukemia, genes of the HOX9 paralogous group and HOXA10 were frequently overexpressed. For HOXB9, we confirmed that elevated RNA was associated with protein overexpression. In some cases, marked HOX overexpression was associated with elevated FGF10 and FGF17. During development, the WNT pathway affects cell fate, polarity, and proliferation, and WNT7a has been implicated in the maintenance of HOX expression. In contrast to normal lung and mortal short-term bronchial epithelial cultures, WNT7a was frequently reduced or absent in lung cancers. In immortalized bronchial epithelial cells, WNT7a was lost concomitantly with HOXA1, and a statistically significant correlation between the expression of both genes was observed in lung cancer cell lines. Furthermore, we identified a homozygous deletion of beta-catenin in the mesothelioma, NCI-H28, associated with reduced WNT7a and the lowest overall cell line expression of HOXA1, HOXA7, HOXA9, and HOXA10, whereas HOXB9 levels were unaffected. Of note, both WNT7a and beta-catenin are encoded on chromosome 3p, which undergoes frequent loss of heterozygosity in these tumors. Our results suggest that alterations in regulatory circuits involving HOX, WNT, and possibly fibroblast growth factor pathways occur frequently in lung cancer.

Angiogenic squamous dysplasia in bronchi of individuals at high risk for lung cancer

Lung carcinogenesis is assumed to be a multistep process, but detailed understanding of the sequential morphological and molecular changes preceding invasive lung cancer remains elusive. To better understand early lung carcinogenesis, we initiated a program of fluorescence bronchoscopy in smokers at high risk for lung cancer. In the bronchial biopsies from these subjects, we observed a unique lesion consisting of capillary blood vessels closely juxtaposed to and projecting into metaplastic or dysplastic squamous bronchial epithelium, angiogenic squamous dysplasia (ASD). Serial sections of the capillary projections confirmed that they represent intramucosal capillary loops. Microvessel density in ASD was elevated in comparison to normal mucosa (P = 0.0003) but not in comparison to other forms of hyperplasia or dysplasia. ASD thus represents a qualitatively distinct form of angiogenesis in which there is architectural rearrangement of the capillary microvasculature. Genetic analysis of surface epithelium in a random subset of lesions revealed loss of heterozygosity at chromosome 3p in 53% of ASD lesions. No confirmed p53 mutations were identified. Compared with normal epithelium, proliferative activity was markedly elevated in ASD lesions. ASD occurred in 54 of 158 (34%) high-risk smokers without carcinoma and in 6 of 10 patients with squamous carcinoma who underwent fluorescence bronchoscopy. One early-stage invasive carcinoma was noteworthy for the occurrence of ASD juxtaposed to invasive tumor. Seventy-seven (59%) of the ASD lesions were detected by abnormal fluorescence alone. Twenty bronchial sites (11 patients) were rebiopsied 1 year after the initial diagnosis. At nine (45%) of these sites, the lesion was found to persist. The lesion was not present in biopsies from 16 normal nonsmoker control subjects. The presence of this lesion in high-risk smokers suggests that aberrant patterns of microvascularization may occur at an early stage of bronchial carcinogenesis.

Molecular definition of a small amplification domain within 3q26 in tumors of cervix, ovary, and lung

A common amplification target encompassing chromosome region 3q25 to q27 has been identified by comparative genomic hybridization analyses in tumors of the cervix, ovary, endometrium, lung, and head and neck. Because this segment spans at least 30 megabases, we undertook a molecular analysis of copy number to more precisely define the amplification domain. Our Southern blot and fluorescence in situ hybridization results with the use of 17 markers confirmed the presence of low-level 3q amplification events in cervical, ovarian, and variant SCLC tumors. Most of the tumor types studied appeared to have similar, broad amplification domains centered within 3q26.2, suggesting that the same target is being affected in all. The ovarian carcinoma cell line NIH:OVCAR3 had a highly restricted amplification domain spanned by four overlapping YAC clones, suggesting a small target. The region of highest amplification included the gene for the RNA component of telomerase (hTR), supporting it as a potential target. Although the importance of low-level amplification is unknown, the consistent and reproducible nature of this event in a variety of carcinomas suggests that 3q26.2 harbors an oncogene whose low-level amplification has a significant influence on tumor biology.

DEF-3(g16/NY-LU-12), an RNA binding protein from the 3p21.3 homozygous deletion region in SCLC

DEF-3(g16/NY-LU-12) encodes a novel RNA binding protein isolated by positional cloning from an SCLC homozygous deletion region in 3p21.3 and, in parallel, as a differentially expressed gene during myelopoiesis from FDCPmix-A4 cells. DEF-3(g16/NY-LU-12) is ubiquitously expressed during mouse embryogenesis and in adult organs while human hematopoietic tissues showed differential expression. The mouse and human proteins are highly conserved containing two RNA recognition motifs (RRMs) and other domains associated with RNA binding and protein-protein interactions. A database search identified related proteins in human, rat, C. elegans and S. pombe including the 3p21.3 co-deleted gene, LUCA15. Recombinant proteins containing the RRMs of DEF-3(g16/NY-LU-12) and LUCA15 specifically bound poly(G) RNA homopolymers in vitro. These RRMs also show similarity to those of the Hu protein family. Since anti-Hu RRM domain antibodies are associated with an anti-tumor effect and paraneoplastic encephalomyelitis, we tested sera from Hu syndrome patients with the RRMs of DEF-3(g16/NY-LU-12) and LUCA15. These were non-reactive. Thus, DEF-3(g16/NY-LU-12) and LUCA15 represent members of a novel family of RNA binding proteins with similar expression patterns and in vitro RNA binding characteristics. They are co-deleted in some lung cancers and immunologically distinct from the Hu proteins.

Chromosomal duplication accompanies allelic loss in non-small cell lung carcinoma

Hemizygous deletion in the short (p) arm of chromosome 3 is a common finding in non-small cell lung carcinoma (NSCLC) and is postulated to be a crucial early change in lung tumorigenesis. Yet one of the most frequent nuclear abnormalities in both NSCLC and premalignant bronchial epithelium is increase in chromosomal copy number. Deletion and duplication have not been assessed in the same tumor set by both molecular and cytogenetic methods to determine whether allelic loss correlates with chromosomal duplication in the same tumor cell populations. It is also not established what biological mechanisms might lead to allelic deletion and chromosomal duplication. We have investigated changes in the copy number of chromosome 3 in touch preparations of 38 NSCLCs (19 adenocarcinomas and 19 squamous cell carcinomas) using dual-target, dual-color fluorescence in situ hybridization (FISH) assays. Chromosome 3 centromere probe was matched with a 3p14.2 probe [intron 4 of the fragile histidine triad (FHIT) gene] and a 3p21.31 probe (HSemaIV gene). We then correlated FISH results with results of molecular analyses for allelic losses at loci in the regions to which the FISH probes mapped in 20 of these cases. Although various combinations of FISH abnormalities were sometimes detected within the same specimens, individual cases could be classified according to the predominant FISH pattern, usually with one abnormality present in >60% of tumor cells. Chromosomal duplication, indicated by the presence of more than two centromeric signals, was the most frequent abnormality observed by FISH and was accompanied by loss of specific sequences on 3p in approximately one-half of the specimens in which it was observed. The most frequent abnormality observed by molecular analysis was loss of heterozygosity (LOH) in both of the chromosomal regions tested and was demonstrated in 83% of cases with chromosomal duplication. We conclude that LOH may occur in the presence of chromosomal duplication, suggesting that the duplicated chromosome is homozygous. Our findings imply that LOH occurs before chromosomal duplication during lung carcinogenesis.