Inter- and intra-breed genome-wide copy number diversity in a large cohort of European equine breeds.

BACKGROUND: Copy Number Variation (CNV) is a common form of genetic variation underlying animal evolution and phenotypic diversity across a wide range of species. In the mammalian genome, high frequency of CNV differentiation between breeds may be candidates for population-specific selection. However, CNV differentiation, selection and its population genetics have been poorly explored in horses. RESULTS: We investigated the patterns, population variation and gene annotation of CNV using the Axiom® Equine Genotyping Array (670,796 SNPs) from a large cohort of individuals (N = 1755) belonging to eight European horse breeds, varying from draught horses to several warmblood populations. After quality control, 152,640 SNP CNVs (individual markers), 18,800 segment CNVs (consecutive SNP CNVs of same gain/loss state or both) and 939 CNV regions (CNVRs; overlapping segment CNVs by at least 1 bp) compared to the average signal of the reference (Belgian draught horse) were identified. Our analyses showed that Equus caballus chromosome 12 (ECA12) was the most enriched in segment CNV gains and losses (~ 3% average proportion of the genome covered), but the highest number of segment CNVs were detected on ECA1 and ECA20 (regardless of size). The Friesian horses showed private SNP CNV gains (> 20% of the samples) on ECA1 and Exmoor ponies displayed private SNP CNV losses on ECA25 (> 20% of the samples). The Warmblood cluster showed private SNP CNV gains located in ECA9 and Draught cluster showed private SNP CNV losses located in ECA7. The length of the CNVRs ranged from 1 kb to 21.3 Mb. A total of 10,612 genes were annotated within the CNVRs. The PANTHER annotation of these genes showed significantly under- and overrepresented gene ontology biological terms related to cellular processes and immunity (Bonferroni P-value < 0.05). We identified 80 CNVRs overlapping with known QTL for fertility, coat colour, conformation and temperament. We also report 67 novel CNVRs. CONCLUSIONS: This work revealed that CNV patterns, in the genome of some European horse breeds, occurred in specific genomic regions. The results provide support to the hypothesis that high frequency private CNVs residing in genes may potentially be responsible for the diverse phenotypes seen between horse breeds.

Primary glioblastoma cells for precision medicine: a quantitative portrait of genomic (in)stability during the first 30 passages.

Background: Primary glioblastoma cell (GC) cultures have emerged as a key model in brain tumor research, with the potential to uncover patient-specific differences in therapy response. However, there is limited quantitative information about the stability of such cells during the initial 20-30 passages of culture. Methods: We interrogated 3 patient-derived GC cultures at dense time intervals during the first 30 passages of culture. Combining state-of-the-art signal processing methods with a mathematical model of growth, we estimated clonal composition, rates of change, affected pathways, and correlations between altered gene dosage and transcription. Results: We demonstrate that GC cultures undergo sequential clonal takeovers, observed through variable proportions of specific subchromosomal lesions, variations in aneuploid cell content, and variations in subpopulation cell cycling times. The GC cultures also show significant transcriptional drift in several metabolic and signaling pathways, including ribosomal synthesis, telomere packaging and signaling via the mammalian target of rapamycin, Wnt, and interferon pathways, to a high degree explained by changes in gene dosage. In addition to these adaptations, the cultured GCs showed signs of shifting transcriptional subtype. Compared with chromosomal aberrations and gene expression, DNA methylations remained comparatively stable during passaging, and may be favorable as a biomarker. Conclusion: Taken together, GC cultures undergo significant genomic and transcriptional changes that need to be considered in functional experiments and biomarker studies that involve primary glioblastoma cells.

Gene expression profiles in preterm infants on continuous long­term oxygen therapy suggest reduced oxidative stress­dependent signaling during hypoxia.

Preterm infants are susceptible to neonatal inflammatory/infective diseases requiring drug therapy. The present study hypothesized that mRNA expression in the blood may be modulated by signaling pathways during treatment. The current study aimed to explore changes in global gene expression in the blood from preterm infants with the objective of identifying patterns or pathways of potential relevance to drug therapy. The infants involved were selected based on maternal criteria indicating increased risk for therapeutic intervention. Global mRNA expression was measured in 107 longitudinal whole blood samples using Affymetrix Human­Genome­U133 Plus 2.0­arrays; samples were obtained from 20 preterm infants. Unsupervised clustering revealed a distinct homogeneous gene expression pattern in 13 samples derived from seven infants undergoing continuous oxygen therapy. At these sampling times, all but one of the seven infants exhibited severe drops in peripheral capillary saturation levels below 60%. The infants were reoxygenated with 100% inspired oxygen concentration. The other samples (n=94) represented the infants from the cohort at time points when they did not undergo continuous oxygen therapy. Comparing these two sets of samples identified a distinct gene expression pattern of 5,986 significantly differentially expressed genes, of which 5,167 genes exhibited reduced expression levels during transient hypoxia. This expression pattern was reversed when the infants became stable, i.e., when they were not continuously oxygenated and had no events of hypoxia. To identify signaling pathways involved in gene regulation, the Database for Annotation, Visualization and Integrated Discovery online tool was used. Mitogen­activated protein kinases, which are normally induced by oxidative stress, exhibited reduced gene expression during hypoxia. In addition, nuclear factor erythroid 2­related factor 2­antioxidant response element target genes involved in oxidative stress protection were also expressed at lower levels, suggesting reduced transcription of this pathway. The findings of the present study suggest that oxidative stress­dependent signaling is reduced during hypoxia. Understanding the molecular response in preterm infants during continuous oxygenation may aid in refining therapeutic strategies for oxygen therapy.

Microsatellite instability and mutations in BRAF and KRAS are significant predictors of disseminated disease in colon cancer.

BACKGROUND: Molecular alterations are well studied in colon cancer, however there is still need for an improved understanding of their prognostic impact. This study aims to characterize colon cancer with regard to KRAS, BRAF, and PIK3CA mutations, microsatellite instability (MSI), and average DNA copy number, in connection with tumour dissemination and recurrence in patients with colon cancer. METHODS: Disease stage II-IV colon cancer patients (n = 121) were selected. KRAS, BRAF, and PIK3CA mutation status was assessed by pyrosequencing and MSI was determined by analysis of mononucleotide repeat markers. Genome-wide average DNA copy number and allelic imbalance was evaluated by SNP array analysis. RESULTS: Patients with mutated KRAS were more likely to experience disease dissemination (OR 2.75; 95% CI 1.28-6.04), whereas the opposite was observed for patients with BRAF mutation (OR 0.34; 95% 0.14-0.81) or MSI (OR 0.24; 95% 0.09-0.64). Also in the subset of patients with stage II-III disease, both MSI (OR 0.29; 95% 0.10-0.86) and BRAF mutation (OR 0.32; 95% 0.16-0.91) were related to lower risk of distant recurrence. However, average DNA copy number and PIK3CA mutations were not associated with disease dissemination. CONCLUSIONS: The present study revealed that tumour dissemination is less likely to occur in colon cancer patients with MSI and BRAF mutation, whereas the presence of a KRAS mutation increases the likelihood of disseminated disease.

Intratumoral genome diversity parallels progression and predicts outcome in pediatric cancer.

Genetic differences among neoplastic cells within the same tumour have been proposed to drive cancer progression and treatment failure. Whether data on intratumoral diversity can be used to predict clinical outcome remains unclear. We here address this issue by quantifying genetic intratumoral diversity in a set of chemotherapy-treated childhood tumours. By analysis of multiple tumour samples from seven patients we demonstrate intratumoral diversity in all patients analysed after chemotherapy, typically presenting as multiple clones within a single millimetre-sized tumour sample (microdiversity). We show that microdiversity often acts as the foundation for further genome evolution in metastases. In addition, we find that microdiversity predicts poor cancer-specific survival (60%; P=0.009), independent of other risk factors, in a cohort of 44 patients with chemotherapy-treated childhood kidney cancer. Survival was 100% for patients lacking microdiversity. Thus, intratumoral genetic diversity is common in childhood cancers after chemotherapy and may be an important factor behind treatment failure.

1p36 deletion is a marker for tumour dissemination in microsatellite stable stage II-III colon cancer.

BACKGROUND: The clinical behaviour of colon cancer is heterogeneous. Five-year overall survival is 50-65% with all stages included. Recurring somatic chromosomal alterations have been identified and some have shown potential as markers for dissemination of the tumour, which is responsible for most colon cancer deaths. We investigated 115 selected stage II-IV primary colon cancers for associations between chromosomal alterations and tumour dissemination. METHODS: Follow-up was at least 5 years for stage II-III patients without distant recurrence. Affymetrix SNP 6.0 microarrays and allele-specific copy number analysis were used to identify chromosomal alterations. Fisher's exact test was used to associate alterations with tumour dissemination, detected at diagnosis (stage IV) or later as recurrent disease (stage II-III). RESULTS: Loss of 1p36.11-21 was associated with tumour dissemination in microsatellite stable tumours of stage II-IV (odds ratio = 5.5). It was enriched to a similar extent in tumours with distant recurrence within stage II and stage III subgroups, and may therefore be used as a prognostic marker at diagnosis. Loss of 1p36.11-21 relative to average copy number of the genome showed similar prognostic value compared to absolute loss of copies. Therefore, the use of relative loss as a prognostic marker would benefit more patients by applying also to hyperploid cancer genomes. The association with tumour dissemination was supported by independent data from the The Cancer Genome Atlas. CONCLUSION: Deletions on 1p36 may be used to guide adjuvant treatment decisions in microsatellite stable colon cancer of stages II and III.

AKN-028 induces cell cycle arrest, downregulation of Myc associated genes and dose dependent reduction of tyrosine kinase activity in acute myeloid leukemia.

AKN-028 is a novel tyrosine kinase inhibitor with preclinical activity in acute myeloid leukemia (AML), presently undergoing investigation in a phase I/II study. It is a potent inhibitor of the FMS-like kinase 3 (FLT3) but shows in vitro activity in a wide range of AML samples. In the present study, we have characterized the effects of AKN-028 on AML cells in more detail. AKN-028 induced a dose-dependent G0/1 arrest in AML cell line MV4-11. Treatment with AKN-028 caused significantly altered gene expression in all AML cell types tested (430 downregulated, 280 upregulated transcripts). Subsequent gene set enrichment analysis revealed enrichment of genes associated with the proto-oncogene and cell cycle regulator c-Myc among the downregulated genes in both AKN-028 and midostaurin treated cells. Kinase activity profiling in AML cell lines and primary AML samples showed that tyrosine kinase activity, but not serine/threonine kinase activity, was inhibited by AKN-028 in a dose dependent manner in all samples tested, reaching approximately the same level of kinase activity. Cells sensitive to AKN-028 showed a higher overall tyrosine kinase activity than more resistant ones, whereas serine/threonine kinase activity was similar for all primary AML samples. In summary, AKN-028 induces cell cycle arrest in AML cells, downregulates Myc-associated genes and affect several signaling pathways. AML cells with high global tyrosine kinase activity seem to be more sensitive to the cytotoxic effect of AKN-028 in vitro.

Synergistic interactions between camptothecin and EGFR or RAC1 inhibitors and between imatinib and Notch signaling or RAC1 inhibitors in glioblastoma cell lines.

PURPOSE: The current treatment strategies for glioblastoma have limited health and survival benefits for the patients. A common obstacle in the treatment is chemoresistance. A possible strategy to evade this problem may be to combine chemotherapeutic drugs with agents inhibiting resistance mechanisms. The aim with this study was to identify molecular pathways influencing drug resistance in glioblastoma-derived cells and to evaluate the potential of pharmacological interference with these pathways to identify synergistic drug combinations. METHODS: Global gene expressions and drug sensitivities to three chemotherapeutic drugs (imatinib, camptothecin and temozolomide) were measured in six human glioblastoma-derived cell lines. Gene expressions that correlated to drug sensitivity or resistance were identified and mapped to specific pathways. Selective inhibitors of these pathways were identified. The effects of six combinations of inhibitors and chemotherapeutic drugs were evaluated in glioblastoma-derived cell lines. Drug combinations with synergistic effects were also evaluated in non-cancerous epithelial cells. RESULTS: Four drug combinations had synergistic effects in at least one of the tested glioblastoma-derived cell lines; camptothecin combined with gefitinib (epidermal growth factor receptor inhibitor) or NSC 23766 (ras-related C3 botulinum toxin substrate 1 inhibitor) and imatinib combined with DAPT (Notch signaling inhibitor) or NSC 23766. Of these, imatinib combined with DAPT or NSC 23766 did not have synergistic effects in non-cancerous epithelial cells. Two drug combinations had at least additive effects in one of the tested glioblastoma-derived cell lines; temozolomide combined with gefitinib or PF-573228 (focal adhesion kinase inhibitor). CONCLUSION: Four synergistic and two at least additive drug combinations were identified in glioblastoma-derived cells. Pathways targeted by these drug combinations may serve as targets for future drug development with the potential to increase efficacy of currently used/evaluated chemotherapy.

Impaired autophagy, chaperone expression, and protein synthesis in response to critical illness interventions in porcine skeletal muscle.

Critical illness myopathy (CIM) is characterized by a preferential loss of the motor protein myosin, muscle wasting, and impaired muscle function in critically ill intensive care unit (ICU) patients. CIM is associated with severe morbidity and mortality and has a significant negative socioeconomic effect. Neuromuscular blocking agents, corticosteroids, sepsis, mechanical ventilation, and immobilization have been implicated as important risk factors, but the causal relationship between CIM and the risk factors has not been established. A porcine ICU model has been used to determine the immediate molecular and cellular cascades that may contribute to the pathogenesis prior to myosin loss and extensive muscle wasting. Expression profiles have been compared between pigs exposed to the ICU interventions, i.e., mechanically ventilated, sedated, and immobilized for 5 days, with pigs exposed to critical illness interventions, i.e., neuromuscular blocking agents, corticosteroids, and induced sepsis in addition to the ICU interventions for 5 days. Impaired autophagy as well as impaired chaperone expression and protein synthesis were observed in the skeletal muscle in response to critical illness interventions. A novel finding in this study is impaired core autophagy machinery in response to critical illness interventions, which when in concert with downregulated chaperone expression and protein synthesis may collectively affect the proteostasis in skeletal muscle and may exacerbate the disease progression in CIM.

Distinct transcriptional control in major immunogenetic subsets of chronic lymphocytic leukemia exhibiting subset-biased global DNA methylation profiles.

Chronic lymphocytic leukemia (CLL) can be divided into prognostic subgroups based on the IGHV gene mutational status, and is further characterized by multiple subsets of cases with quasi-identical or stereotyped B cell receptors that also share clinical and biological features. We recently reported differential DNA methylation profiles in IGHV-mutated and IGHV-unmutated CLL subgroups. For the first time, we here explore the global methylation profiles of stereotyped subsets with different prognosis, by applying high-resolution methylation arrays on CLL samples from three major stereotyped subsets: the poor-prognostic subsets #1 (n = 15) and #2 (n = 9) and the favorable-prognostic subset #4 (n = 15). Overall, the three subsets exhibited significantly different methylation profiles, which only partially overlapped with those observed in our previous study according to IGHV gene mutational status. Specifically, gene ontology analysis of the differentially methylated genes revealed a clear enrichment of genes involved in immune response, such as B cell activation (e.g., CD80, CD86 and IL10), with higher methylation levels in subset #1 than subsets #2 and #4. Accordingly, higher expression of the co-stimulatory molecules CD80 and CD86 was demonstrated in subset #4 vs. subset #1, pointing to a key role for these molecules in the crosstalk of CLL subset #4 cells with the microenvironment. In summary, investigation of three prototypic, stereotyped CLL subsets revealed distinct DNA methylation profiles for each subset, which suggests subset-biased patterns of transcriptional control and highlights a key role for epigenetics during leukemogenesis.

CD99 is a novel prognostic stromal marker in non-small cell lung cancer.

The complex interaction between cancer cells and the microenvironment plays an essential role in all stages of tumourigenesis. Despite the significance of this interplay, alterations in protein composition underlying tumour-stroma interactions are largely unknown. The aim of this study was to identify stromal proteins with clinical relevance in non-small cell lung cancer (NSCLC). A list encompassing 203 stromal candidate genes was compiled based on gene expression array data and available literature. The protein expression of these genes in human NSCLC was screened using the Human Protein Atlas. Twelve proteins were selected that showed a differential stromal staining pattern (BGN, CD99, DCN, EMILIN1, FBN1, PDGFRB, PDLIM5, POSTN, SPARC, TAGLN, TNC and VCAN). The corresponding antibodies were applied on tissue microarrays, including 190 NSCLC samples, and stromal staining was correlated with clinical parameters. Higher stromal expression of CD99 was associated with better prognosis in the univariate (p = 0.037) and multivariate (p = 0.039) analysis. The association was independent from the proportion of tumour stroma, the fraction of inflammatory cells and clinical and pathological parameters like stage, performance status and tumour histology. The prognostic impact of stromal CD99 protein expression was confirmed in an independent cohort of 240 NSCLC patients (p = 0.008). Furthermore, double-staining confocal fluorescence microscopy showed that CD99 was expressed in stromal lymphocytes as well as in cancer-associated fibroblasts. Based on a comprehensive screening strategy the membrane protein CD99 was identified as a novel stromal factor with clinical relevance. The results support the concept that stromal properties have an important impact on tumour progression.

A comprehensive analysis of human gene expression profiles identifies stromal immunoglobulin κ C as a compatible prognostic marker in human solid tumors.

PURPOSE: Although the central role of the immune system for tumor prognosis is generally accepted, a single robust marker is not yet available. EXPERIMENTAL DESIGN: On the basis of receiver operating characteristic analyses, robust markers were identified from a 60-gene B cell-derived metagene and analyzed in gene expression profiles of 1,810 breast cancer; 1,056 non-small cell lung carcinoma (NSCLC); 513 colorectal; and 426 ovarian cancer patients. Protein and RNA levels were examined in paraffin-embedded tissue of 330 breast cancer patients. The cell types were identified with immunohistochemical costaining and confocal fluorescence microscopy. RESULTS: We identified immunoglobulin κ C (IGKC) which as a single marker is similarly predictive and prognostic as the entire B-cell metagene. IGKC was consistently associated with metastasis-free survival across different molecular subtypes in node-negative breast cancer (n = 965) and predicted response to anthracycline-based neoadjuvant chemotherapy (n = 845; P < 0.001). In addition, IGKC gene expression was prognostic in NSCLC and colorectal cancer. No association was observed in ovarian cancer. IGKC protein expression was significantly associated with survival in paraffin-embedded tissues of 330 breast cancer patients. Tumor-infiltrating plasma cells were identified as the source of IGKC expression. CONCLUSION: Our findings provide IGKC as a novel diagnostic marker for risk stratification in human cancer and support concepts to exploit the humoral immune response for anticancer therapy. It could be validated in several independent cohorts and carried out similarly well in RNA from fresh frozen as well as from paraffin tissue and on protein level by immunostaining.

Allele-specific copy number analysis of tumor samples with aneuploidy and tumor heterogeneity.

We describe a bioinformatic tool, Tumor Aberration Prediction Suite (TAPS), for the identification of allele-specific copy numbers in tumor samples using data from Affymetrix SNP arrays. It includes detailed visualization of genomic segment characteristics and iterative pattern recognition for copy number identification, and does not require patient-matched normal samples. TAPS can be used to identify chromosomal aberrations with high sensitivity even when the proportion of tumor cells is as low as 30%. Analysis of cancer samples indicates that TAPS is well suited to investigate samples with aneuploidy and tumor heterogeneity, which is commonly found in many types of solid tumors.

Gene copy number aberrations are associated with survival in histologic subgroups of non-small cell lung cancer.

INTRODUCTION: Non-small cell lung cancer (NSCLC) is characterized by a multitude of genetic aberrations with unknown clinical impact. In this study, we aimed to identify gene copy number changes that correlate with clinical outcome in NSCLC. To maximize the chance to identify clinically relevant events, we applied a strategy involving two prognostically extreme patient groups. METHODS: Short-term (<20 month; n = 53) and long-term survivors (>58 month; n = 47) were selected from a clinically well-characterized NSCLC patient cohort with available fresh frozen tumor specimens. The samples were analyzed using high-resolution single-nucleotide polymorphism array technology to assess gene copy number variations and array-based gene expression profiling. The molecular data were combined with information on clinical parameters. RESULTS: Genetic aberrations were strongly associated with tumor histology. In adenocarcinoma (n = 50), gene copy number gains on chromosome 8q21-q24.3 (177 genes) were more frequent in long-term than in short-term survivors. In squamous cell carcinoma (n = 28), gains on chromosome 14q23.1-24.3 (133 genes) were associated with shorter survival, whereas losses in a neighboring region, 14q31.1-32.33 (110 genes), correlated with favorable outcome. In accordance with copy number gains and losses, messenger RNA expression levels of corresponding genes were increased or decreased, respectively. CONCLUSION: Comprehensive tumor profiling permits the integration of genomic, histologic, and clinical data. We identified gene copy number gains and losses, with corresponding changes in messenger RNA levels that were associated with prognosis in adenocarcinoma and squamous cell carcinoma of the lung.