XLSX file - 564K, Supplementary Table S1: This table lists 459 genes that show a differential expression upon loss of MALAT1 in A549 lung cancer cells.
PDF file - 808K, Supplementary Figure S1: This figure depicts the impact of MALAT1 loss on gene expression, splicing and SR protein phosphorylation. Supplementary Figure S2: This figure describes the generation of MALAT1-Knockout A549 cells using an independent ZFN as well as their phenotypes regarding proliferation and MALAT1 target gene expression. Supplementary Figure S3: This figure displays the impact of loss of MALAT1 using an independent ZFN in A549 cells on cell migration. Supplementary Figure S4: This figure documents that Antisense Oligonucleotides (ASOs) are effective in silencing MALAT1 in vitro without affecting cell proliferation of EBC-1 cells. Supplementary Table S2: This table lists 23 genes whose differential expression (5 up / 18 down) in MALAT1 KO cells was validated via qRT-PCR and who had been previously identified with critical roles in lung cancer, migration, invasion, EMT or metastasis. Supplementary Table S3: This table lists the sequences of all primers used for qRT-PCR in 5'-3' direction. Supplementary Table S4: This table lists the sequences of all primers used for splicing analysis in 5'-3' direction. Supplementary Table S5: This table lists the sequences of all primers and probes used for TaqMan qRT-PCR in 5'-3' direction. Supplementary Table S6: This table lists the sequences of all Antisense Oligonucleotides (ASOs) in 5'-3' direction. Supplementary Methods: This chapter provides experimental details on the RNA isolation and DNase I digest, reverse transcription and quantitative PCR, exon microarray analysis, antisense oligonucleotides (ASOs), lung imaging by microCT scan, immunohistochemistry and in situ hybridization, statistical analysis, generation of ZFN-2 clones, cell proliferation assays, SDS-PAGE and Western blotting.
Long intergenic non-coding RNA- Nucleotide Metabolism Regulator (lincNMR ) is a long non-coding RNA (lncRNA) which is induced in hepatocellular carcinoma. Its depletion invokes a proliferation defect, triggers senescence and inhibits colony formation in liver, but also breast and lung cancer cells. Triple-label SILAC proteomics profiles reveal a deregulation of key cell cycle regulators in lincNMR -depleted cells like the key dNTP synthesizing enzymes RRM2, TYMS and TK1, implicating lincNMR in regulating nucleotide metabolism. LincNMR silencing decreases dNTP levels, while exogenous dNTPs rescues the proliferation defect induced by lincNMR depletion. In vivo RNA Antisense Purification (RAP-MS) identifies YBX1 as a direct interaction partner of lincNMR which regulates RRM2, TYMS and TK1 expression and binds to their promoter regions. In a Chick Chorioallantoic Membrane (CAM) in vivo model, lincNMR -depleted tumors are significantly smaller. In summary, we discover a lincRNA, lincNMR , which regulates tumor cell proliferation through a YBX1-RRM2-TYMS-TK1 axis governing nucleotide metabolism.
Nonstop or stop-loss mutations convert a stop into a sense codon, resulting in translation into the 3′ untranslated region as a nonstop extension mutation to the next in-frame stop codon or as a readthrough mutation into the poly-A tail. Nonstop mutations have been characterized in hereditary diseases, but not in cancer genetics. In a pan-cancer analysis, we curated and analysed 3,412 nonstop mutations from 62 tumour entities, generating a comprehensive database at http://NonStopDB.dkfz.de . Six different nonstop extension mutations affected the tumour suppressor SMAD4, extending its carboxy terminus by 40 amino acids. These caused rapid degradation of the SMAD4 mutants via the ubiquitin–proteasome system. A hydrophobic degron signal sequence of ten amino acids within the carboxy-terminal extension was required to induce complete loss of the SMAD4 protein. Thus, we discovered that nonstop mutations can be functionally important in cancer and characterize their loss-of-function impact on the tumour suppressor SMAD4.
Synonymous mutations have been viewed as silent mutations, since they only affect the DNA and mRNA, but not the amino acid sequence of the resulting protein. Nonetheless, recent studies suggest their significant impact on splicing, RNA stability, RNA folding, translation or co-translational protein folding. Hence, we compile 659194 synonymous mutations found in human cancer and characterize their properties. We provide the user-friendly, comprehensive resource for synonymous mutations in cancer, SynMICdb ( http://SynMICdb.dkfz.de ), which also contains orthogonal information about gene annotation, recurrence, mutation loads, cancer association, conservation, alternative events, impact on mRNA structure and a SynMICdb score. Notably, synonymous and missense mutations are depleted at the 5'-end of the coding sequence as well as at the ends of internal exons independent of mutational signatures. For patient-derived synonymous mutations in the oncogene KRAS , we indicate that single point mutations can have a relevant impact on expression as well as on mRNA secondary structure.
Aberrant expression of noncoding RNAs plays a critical role during tumorigenesis. To uncover novel functions of long non-coding RNA (lncRNA) in lung adenocarcinoma, we used a microarray-based screen identifying LINC00673 with elevated expression in matched tumor versus normal tissue. We report that loss of LINC00673 is sufficient to trigger cellular senescence, a tumor suppressive mechanism associated with permanent cell cycle arrest, both in lung cancer and normal cells in a p53-dependent manner. LINC00673-depleted cells fail to efficiently transit from G1- to S-phase. Using a quantitative proteomics approach, we confirm the modulation of senescence-associated genes as a result of LINC00673 knockdown. In addition, we uncover that depletion of p53 in normal and tumor cells is sufficient to overcome LINC00673-mediated cell cycle arrest and cellular senescence. Furthermore, we report that overexpression of LINC00673 reduces p53 translation and contributes to the bypass of Ras-induced senescence. In summary, our findings highlight LINC00673 as a crucial regulator of proliferation and cellular senescence in lung cancer.
Breast cancer is a leading cause of cancer-related death in women. Small open reading frame (sORF)-encoded proteins or microproteins constitute a new class of molecules often transcribed from presumed long non-coding RNA transcripts (lncRNAs). The translation of some of these sORFs has been confirmed, but their cellular function and importance remains largely unknown. Here, we report the identification and characterization of a novel microprotein of 10 kDa, which we named Cancer-Associated Small Integral Membrane Open reading frame 1 (CASIMO1). CASIMO1 RNA is overexpressed predominantly in hormone receptor-positive breast tumors. Its knockdown leads to decreased proliferation in multiple breast cancer cell lines. Its loss disturbs the organization of the actin cytoskeleton, leads to inhibition of cell motility, and causes a G0/G1 cell cycle arrest. The proliferation phenotype upon overexpression is observed only with CASIMO1 protein expression, but not with a non-translatable mutant attributing the effects to the sORF-derived protein rather than a lncRNA function. CASIMO1 microprotein interacts with squalene epoxidase (SQLE), a key enzyme in cholesterol synthesis and a known oncogene in breast cancer. Overexpression of CASIMO1 leads to SQLE protein accumulation without affecting its RNA levels and increased lipid droplet clustering, while knockdown of CASIMO1 decreased SQLE protein abundance and ERK phosphorylation downstream of SQLE. Importantly, SQLE knockdown mimicked the CASIMO1 knockdown phenotype and in turn SQLE overexpression fully rescued the effect of CASIMO1 knockdown. These findings establish CASIMO1 as the first functional microprotein that plays a role in carcinogenesis and is implicated in the cell lipid homeostasis.
The identification of viability‐associated long noncoding RNAs (lncRNAs) might be a promising rationale for new therapeutic approaches in liver cancer. Here, we applied an RNA interference screening approach in hepatocellular carcinoma (HCC) cell lines to find viability‐associated lncRNAs. Among the multiple identified lncRNAs with a significant impact on HCC cell viability, we selected cancer susceptibility 9 (CASC9) due to the strength of its phenotype, expression, and up‐regulation in HCC versus normal liver. CASC9 regulated viability across multiple HCC cell lines as shown by clustered regularly interspaced short palindromic repeats interference and single small interfering RNA (siRNA)–mediated and siRNA pool–mediated depletion of CASC9. Further, CASC9 depletion caused an increase in apoptosis and a decrease of proliferation. We identified the RNA binding protein heterogeneous nuclear ribonucleoprotein L (HNRNPL) as a CASC9 interacting protein by RNA affinity purification and validated it by native RNA immunoprecipitation. Knockdown of HNRNPL mimicked the loss‐of‐viability phenotype observed upon CASC9 depletion. Analysis of the proteome (stable isotope labeling with amino acids in cell culture) of CASC9‐depleted and HNRNPL‐depleted cells revealed a set of coregulated genes which implied a role of the CASC9:HNRNPL complex in AKT signaling and DNA damage sensing. CASC9 expression levels were elevated in patient‐derived tumor samples compared to normal control tissue and had a significant association with overall survival of HCC patients. In a xenograft chicken chorioallantoic membrane model, we measured decreased tumor size after knockdown of CASC9. Conclusion: Taken together, we provide a comprehensive list of viability‐associated lncRNAs in HCC; we identified the CASC9:HNRNPL complex as a clinically relevant viability‐associated lncRNA/protein complex which affects AKT signaling and DNA damage sensing in HCC.
The CRISPR/Cas9 system provides a revolutionary genome editing tool for all areas of molecular biology. In long non-coding RNA (lncRNA) research, the Cas9 nuclease can delete lncRNA genes or introduce RNA-destabilizing elements into their locus. The nuclease-deficient dCas9 mutant retains its RNA-dependent DNA-binding activity and can modulate gene expression when fused to transcriptional repressor or activator domains. Here, we systematically analyze whether CRISPR approaches are suitable to target lncRNAs. Many lncRNAs are derived from bidirectional promoters or overlap with promoters or bodies of sense or antisense genes. In a genome-wide analysis, we find only 38% of 15929 lncRNA loci are safely amenable to CRISPR applications while almost two-thirds of lncRNA loci are at risk to inadvertently deregulate neighboring genes. CRISPR- but not siPOOL or Antisense Oligo (ASO)-mediated targeting of lncRNAs NOP14-AS1, LOC389641, MNX1-AS1 or HOTAIR also affects their respective neighboring genes. Frequently overlooked, the same restrictions may apply to mRNAs. For example, the tumor suppressor TP53 and its head-to-head neighbor WRAP53 are jointly affected by the same sgRNAs but not siPOOLs. Hence, despite the advantages of CRISPR/Cas9 to modulate expression bidirectionally and in cis, approaches based on ASOs or siPOOLs may be the better choice to target specifically the transcript from complex loci.
Long non-coding RNAs (lncRNAs) have been proven to play important roles in diverse cellular processes including the DNA damage response. Nearly 40% of annotated lncRNAs are transcribed in antisense direction to other genes and have often been implicated in their regulation via transcript- or transcription-dependent mechanisms. However, it remains unclear whether inverse correlation of gene expression would generally point toward a regulatory interaction between the genes. Here, we profiled lncRNA and mRNA expression in lung and liver cancer cells after exposure to DNA damage. Our analysis revealed two pairs of mRNA-lncRNA sense-antisense transcripts being inversely expressed upon DNA damage. The lncRNA NOP14-AS1 was strongly upregulated upon DNA damage, while the mRNA for NOP14 was downregulated, both in a p53-dependent manner. For another pair, the lncRNA LIPE-AS1 was downregulated, while its antisense mRNA CEACAM1 was upregulated. To test whether as expected the antisense genes would regulate each other resulting in this highly significant inverse correlation, we employed antisense oligonucleotides and RNAi to study transcript-dependent effects as well as dCas9-based transcriptional modulation by CRISPRi/CRISPRa for transcription-dependent effects. Surprisingly, despite the strong stimulus-dependent inverse correlation, our data indicate that neither transcript- nor transcription-dependent mechanisms explain the inverse regulation of NOP14-AS1:NOP14 or LIPE-AS1:CEACAM1 expression. Hence, sense-antisense pairs whose expression is strongly-positively or negatively-correlated can be nonetheless regulated independently. This highlights the requirement of individual experimental studies for each antisense pair and prohibits drawing conclusions on regulatory mechanisms from expression correlations.
In recent years, long non-coding RNA (lncRNA) research has identified essential roles of these transcripts in virtually all physiological cellular processes including tumorigenesis, but their functions and molecular mechanisms are poorly understood. In this study, we performed a high-throughput siRNA screen targeting 638 lncRNAs deregulated in cancer entities to analyse their impact on cell division by using time-lapse microscopy. We identified 26 lncRNAs affecting cell morphology and cell cycle including LINC00152. This transcript was ubiquitously expressed in many human cell lines and its RNA levels were significantly upregulated in lung, liver and breast cancer tissues. A comprehensive sequence analysis of LINC00152 revealed a highly similar paralog annotated as MIR4435-2HG and several splice variants of both transcripts. The shortest and most abundant isoform preferentially localized to the cytoplasm. Cells depleted of LINC00152 arrested in prometaphase of mitosis and showed reduced cell viability. In RNA affinity purification (RAP) studies, LINC00152 interacted with a network of proteins that were associated with M phase of the cell cycle. In summary, we provide new insights into the properties and biological function of LINC00152 suggesting that this transcript is crucial for cell cycle progression through mitosis and thus, could act as a non-coding oncogene.
Long noncoding RNAs (lncRNAs) are important regulators of cellular homeostasis. However, their contribution to the cancer phenotype still needs to be established. Herein, we have identified a p53-induced lncRNA, TP53TG1, that undergoes cancer-specific promoter hypermethylation-associated silencing. In vitro and in vivo assays identify a tumor-suppressor activity for TP53TG1 and a role in the p53 response to DNA damage. Importantly, we show that TP53TG1 binds to the multifaceted DNA/RNA binding protein YBX1 to prevent its nuclear localization and thus the YBX1-mediated activation of oncogenes. TP53TG1 epigenetic inactivation in cancer cells releases the transcriptional repression of YBX1-targeted growth-promoting genes and creates a chemoresistant tumor. TP53TG1 hypermethylation in primary tumors is shown to be associated with poor outcome. The epigenetic loss of TP53TG1 therefore represents an altered event in an lncRNA that is linked to classical tumoral pathways, such as p53 signaling, but is also connected to regulatory networks of the cancer cell.
Hepatocarcinogenesis is a stepwise process. It involves several genetic and epigenetic alterations, e.g., loss of tumor suppressor gene expression ( TP53, PTEN, RB ) as well as activation of oncogenes (c- MYC, MET, BRAF, RAS ). However, the role of RNA-binding proteins (RBPs), which regulate tumor suppressor and oncogene expression at the posttranscriptional level, are not well understood in hepatocellular carcinoma (HCC). Here we analyzed RBPs induced in human liver cancer, revealing 116 RBPs with a significant and more than 2-fold higher expression in HCC compared to normal liver tissue. We focused our subsequent analyses on the Insulin-like growth factor 2 messenger RNA (mRNA)-binding protein 1 (IGF2BP1) representing the most strongly up-regulated RBP in HCC in our cohort. Depletion of IGF2BP1 from multiple liver cancer cell lines inhibits proliferation and induces apoptosis in vitro . Accordingly, murine xenograft assays after stable depletion of IGF2BP1 reveal that tumor growth, but not tumor initiation, strongly depends on IGF2BP1 in vivo . At the molecular level, IGF2BP1 binds to and stabilizes the c-MYC and MKI67 mRNAs and increases c-Myc and Ki-67 protein expression, two potent regulators of cell proliferation and apoptosis. These substrates likely mediate the impact of IGF2BP1 in human liver cancer, but certainly additional target genes contribute to its function. Conclusion : The RNA-binding protein IGF2BP1 is an important protumorigenic factor in liver carcinogenesis. Hence, therapeutic targeting of IGF2BP1 may offer options for intervention in human HCC. (Hepatology 2014;59:1900–1911)
Abstract The long non-coding RNA MALAT1 was one of the first lncRNAs associated with cancer: it is a highly conserved nuclear ncRNA and a predictive marker for metastasis development in lung cancer. However, its high abundance and nuclear localization have greatly hampered its functional analysis since it is only inefficiently knocked down by RNA interference (RNAi). To uncover its functional importance, we developed a MALAT1 knockout model in human lung tumor cells by genomically integrating RNA destabilizing elements site-specifically into the MALAT1 locus using Zinc Finger Nucleases (ZFN).This approach yielded a more than 1000-fold silencing of MALAT1 providing a unique loss-of-function model. Proposed mechanisms of action of MALAT1 include regulation of splicing or gene expression. In lung cancer, MALAT1 does not alter alternative splicing but actively regulates gene expression inducing a signature of metastasis-associated genes. Consequently, MALAT1-deficient cells are impaired in migration and form fewer tumor nodules in a mouse xenograft model. Encouraged by this discovery of the essential function of MALAT1 in lung cancer metastasis, we wanted to analyze whether MALAT1 could also be therapeutically targeted: We developed Antisense oligonucleotides (ASOs) effectively blocking MALAT1 expression in the cell culture and in the animal. Notably, MALAT1-ASO treatment prevents metastasis formation after tumor implantation. Thus, targeting MALAT1 with antisense oligonucleotides provides a potential therapeutic approach to prevent lung cancer metastasis with MALAT1 serving as both, predictive marker and therapeutic target. Lastly, regulating gene expression, but not alternative splicing is the critical function of MALAT1 in lung cancer metastasis. In summary, ten years after the discovery of the lncRNA MALAT1 as a biomarker for lung cancer metastasis, our loss-of-function model unravels the active function of MALAT1 as a regulator of gene expression governing hallmarks of lung cancer metastasis. Citation Format: Tony Gutschner, Monika Hämmerle, Moritz Eißmann, Jeff Hsu, Youngsoo Kim, Gene Hung, Alexey Revenko, Gayatri Arun, Marion Stentrup, Matthias Groß, Martin Zörnig, A. Robert MacLeod, David L. Spector, Sven Diederichs. The long non-coding RNA MALAT1 is an essential gene regulator for lung cancer metastasis in a novel human knockout model . [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 1121. doi:10.1158/1538-7445.AM2013-1121
Selected long noncoding RNAs (lncRNAs) have been shown to play important roles in carcinogenesis. Although the cellular functions of these transcripts can be diverse, many lncRNAs regulate gene expression. In contrast, factors that control the expression of lncRNAs remain largely unknown. Here we investigated the impact of RNA binding proteins on the expression of the liver cancer-associated lncRNA HULC (highly up-regulated in liver cancer). First, we validated the strong up-regulation of HULC in human hepatocellular carcinoma. To elucidate posttranscriptional regulatory mechanisms governing HULC expression, we applied an RNA affinity purification approach to identify specific protein interaction partners and potential regulators. This method identified the family of IGF2BPs (IGF2 mRNA-binding proteins) as specific binding partners of HULC. Depletion of IGF2BP1, also known as IMP1, but not of IGF2BP2 or IGF2BP3, led to an increased HULC half-life and higher steady-state expression levels, indicating a posttranscriptional regulatory mechanism. Importantly, HULC represents the first IGF2BP substrate that is destabilized. To elucidate the mechanism by which IGF2BP1 destabilizes HULC, the CNOT1 protein was identified as a novel interaction partner of IGF2BP1. CNOT1 is the scaffold of the human CCR4-NOT deadenylase complex, a major component of the cytoplasmic RNA decay machinery. Indeed, depletion of CNOT1 increased HULC half-life and expression. Thus, IGF2BP1 acts as an adaptor protein that recruits the CCR4-NOT complex and thereby initiates the degradation of the lncRNA HULC. Conclusion: Our findings provide important insights into the regulation of lncRNA expression and identify a novel function for IGF2BP1 in RNA metabolism. (Hepatology 2013;58:1703–1712)
Abstract The highly conserved long non-coding RNA MALAT-1 (Metastasis-Associated in Lung Adenocarcinoma Transcript 1) had been discovered as a prognostic marker associated with poor survival and development of distant metastasis in lung adenocarcinoma. Since then, it has been found to be deregulated in numerous tumor entities and has been linked to splicing. However, its functional relevance in tumor cells remains to be elucidated. Knockdown models for MALAT1 have been described but suffer from insufficient silencing efficiency of the highly abundant, nuclear non-coding RNA (ncRNA). In this project, we have developed a novel strategy to create ncRNA knockouts in human cancer cell lines. We have successfully used a synthetic Zinc Finger Nuclease engineered to target the 5′-region of MALAT1 to stably and biallelically integrate RNA-destabilizing elements into the genome of human lung cancer cells (A549). This approach resulted in a specific and more than 1000-fold silencing of MALAT1 in individual clones compared to a less than 5-fold silencing using siRNAs. Thus, this approach can be used to create functional knockouts of coding as well as non-coding genes also in human tumor cell lines allowing loss-of-function studies also of non-conserved ncRNAs in the future. Phenotypically, the MALAT1-Knockout cells (KO) greatly differ from their parental cell line and wildtype clones (WT): Next to morphological changes, the migration of the KO cells is largely impaired as shown in scratch assays. In xenograft assays after i.v. injection, the KO cells form significantly fewer and smaller lung metastases than their WT counterparts. Since no large difference was observed after subcutaneous injection of the WT and the KO cells, this indicates a specific, active and essential function of MALAT1 in metastasis. Exon microarrays of the WT and KO cell lines have revealed multiple migration- or metastasis-associated transcripts deregulated by loss of MALAT1 and hence potential target genes. These analyses also uncovered, that splicing is likely not the only functional mechanism of MALAT1 in the nucleus. Taken together, we have developed a novel, highly effective approach for the knockout of genes that can be used for non-coding as well as coding RNAs in human tumor cells as well as cells from other species. Knockout of MALAT1 in human lung cancer cells revealed its essential function in metastasis as well as genes directly and indirectly targeted by MALAT1. Citation Format: Tony Gutschner, Moritz Eißmann, Monika Hämmerle, Marion Stentrup, Catherina Hildenbrandt, Matthias Groß, Martin Zörnig, Sven Diederichs. MALAT-1 is essential for lung cancer metastasis in a novel human knockout model [abstract]. In: Proceedings of the AACR Special Conference on Noncoding RNAs and Cancer; 2012 Jan 8-11; Miami Beach, FL. Philadelphia (PA): AACR; Cancer Res 2012;72(2 Suppl):Abstract nr A21.
The metastasis-associated lung adenocarcinoma transcript 1, MALAT1, is a long non-coding RNA (lncRNA) that has been discovered as a marker for lung cancer metastasis. It is highly abundant, its expression is strongly regulated in many tumor entities including lung adenocarcinoma and hepatocellular carcinoma as well as physiological processes, and it is associated with many RNA binding proteins and highly conserved throughout evolution. The nuclear transcript MALAT-1 has been functionally associated with gene regulation and alternative splicing and its regulation has been shown to impact proliferation, apoptosis, migration and invasion.Here, we have developed a human and a mouse knockout system to study the loss-of-function phenotypes of this important ncRNA. In human tumor cells, MALAT1 expression was abrogated using Zinc Finger Nucleases. Unexpectedly, the quantitative loss of MALAT1 did neither affect proliferation nor cell cycle progression nor nuclear architecture in human lung or liver cancer cells. Moreover, genetic loss of Malat1 in a knockout mouse model did not give rise to any obvious phenotype or histological abnormalities in Malat1-null compared with wild-type animals. Thus, loss of the abundant nuclear long ncRNA MALAT1 is compatible with cell viability and normal development.
Abstract The long noncoding RNA MALAT1 (metastasis-associated lung adenocarcinoma transcript 1), also known as MALAT-1 or NEAT2 (nuclear-enriched abundant transcript 2), is a highly conserved nuclear noncoding RNA (ncRNA) and a predictive marker for metastasis development in lung cancer. To uncover its functional importance, we developed a MALAT1 knockout model in human lung tumor cells by genomically integrating RNA destabilizing elements using zinc finger nucleases. The achieved 1,000-fold MALAT1 silencing provides a unique loss-of-function model. Proposed mechanisms of action include regulation of splicing or gene expression. In lung cancer, MALAT1 does not alter alternative splicing but actively regulates gene expression including a set of metastasis-associated genes. Consequently, MALAT1-deficient cells are impaired in migration and form fewer tumor nodules in a mouse xenograft. Antisense oligonucleotides (ASO) blocking MALAT1 prevent metastasis formation after tumor implantation. Thus, targeting MALAT1 with ASOs provides a potential therapeutic approach to prevent lung cancer metastasis with this ncRNA serving as both predictive marker and therapeutic target. Finally, regulating gene expression, but not alternative splicing, is the critical function of MALAT1 in lung cancer metastasis. In summary, 10 years after the discovery of the lncRNA MALAT1 as a biomarker for lung cancer metastasis, our loss-of-function model unravels the active function of MALAT1 as a regulator of gene expression governing hallmarks of lung cancer metastasis. Cancer Res; 73(3); 1180–9. ©2012 AACR.