TGF-ß and BMP signaling are associated with the transformation of glioblastoma to gliosarcoma and then osteosarcoma.

Background: Gliosarcoma, an isocitrate dehydrogenase wildtype (IDH-WT) variant of glioblastoma, is defined by clonal biphasic differentiation into gliomatous and sarcomatous components. While the transformation from a glioblastoma to gliosarcoma is uncommon, the subsequent transformation to osteosarcoma is rare but may provide additional insights into the biology of these typically distinct cancers. We observed a patient initially diagnosed with glioblastoma, that differentiated into gliosarcoma at recurrence, and further evolved to osteosarcoma at the second relapse. Our objective was to characterize the molecular mechanisms of tumor progression associated with this phenotypic transformation. Methods: Tumor samples were collected at all 3 stages of disease and RNA sequencing was performed to capture their transcriptomic profiles. Sequential clonal evolution was confirmed by the maintenance of an identical PTEN mutation throughout the tumor differentiation using the TSO500 gene panel. Publicly available datasets and the Nanostring nCounter technology were used to validate the results. Results: The glioblastoma tumor from this patient possessed mixed features of all 3 TCGA-defined transcriptomic subtypes of an IDH-WT glioblastoma and a proportion of osteosarcoma signatures were upregulated in the original tumor. Analysis showed that enhanced transforming growth factor-ß (TGF-ß) and bone morphogenic protein signaling was associated with tumor transformation. Regulatory network analysis revealed that TGF-ß family signaling committed the lineage tumor to osteogenesis by stimulating the expression of runt-related transcription factor 2 (RUNX2), a master regulator of bone formation. Conclusions: This unusual clinical case provided an opportunity to explore the modulators of longitudinal sarcomatous transformation, potentially uncovering markers indicating predisposition to this change and identification of novel therapeutic targets.

Metabolic plasticity of IDH1-mutant glioma cell lines is responsible for low sensitivity to glutaminase inhibition.

BACKGROUND: Targeting glutamine metabolism in cancer has become an increasingly vibrant area of research. Mutant IDH1 (IDH1 mut ) gliomas are considered good candidates for targeting this pathway because of the contribution of glutamine to their newly acquired function: synthesis of 2-hydroxyglutarate (2HG). METHODS: We have employed a combination of 13C tracers including glutamine and glucose for investigating the metabolism of patient-derived IDH1 mut glioma cell lines through NMR and LC/MS. Additionally, genetic loss-of-function (in vitro and in vivo) approaches were performed to unravel the adaptability of these cell lines to the inhibition of glutaminase activity. RESULTS: We report the adaptability of IDH1 mut cells' metabolism to the inhibition of glutamine/glutamate pathway. The glutaminase inhibitor CB839 generated a decrease in the production of the downstream metabolites of glutamate, including those involved in the TCA cycle and 2HG. However, this effect on metabolism was not extended to viability; rather, our patient-derived IDH1 mut cell lines display a metabolic plasticity that allows them to overcome glutaminase inhibition. CONCLUSIONS: Major metabolic adaptations involved pathways that can generate glutamate by using alternative substrates from glutamine, such as alanine or aspartate. Indeed, asparagine synthetase was upregulated both in vivo and in vitro revealing a new potential therapeutic target for a combinatory approach with CB839 against IDH1 mut gliomas.

Adjuvant treatment improves overall survival in women with high-intermediate risk early-stage endometrial cancer with lymphovascular space invasion.

BACKGROUND: Adjuvant therapy in early-stage endometrial cancer has not shown a clear overall survival benefit, and hence, patient selection remains crucial. OBJECTIVE: To determine whether women with high-intermediate risk, early-stage endometrial cancer with lymphovascular space invasion particularly benefit from adjuvant treatment in improving oncologic outcomes. METHODS: A multi-center retrospective study was conducted in women with stage IA, IB, and II endometrial cancer with lymphovascular space invasion who met criteria for high-intermediate risk by Gynecologic Oncology Group (GOG) 99. Patients were stratified by the type of adjuvant treatment received. Clinical and pathologic features were abstracted. Progression-free and overall survival were evaluated using multivariable analysis. RESULTS: 405 patients were included with the median age of 67 years (range 27-92, IQR 59-73). 75.0% of the patients had full staging with lymphadenectomy, and 8.6% had sentinel lymph node biopsy (total 83.6%). After surgery, 24.9% of the patients underwent observation and 75.1% received adjuvant therapy, which included external beam radiation therapy (15.1%), vaginal brachytherapy (45.4%), and combined brachytherapy + chemotherapy (19.1%). Overall, adjuvant treatment resulted in improved oncologic outcomes for both 5-year progression-free survival (77.2% vs 69.6%, HR 0.55, p=0.01) and overall survival (81.5% vs 60.2%, HR 0.42, p<0.001). After adjusting for stage, grade 2/3, and age, improved progression-free survival and overall survival were observed for the following adjuvant subgroups compared with observation: external beam radiation (overall survival HR 0.47, p=0.047, progression-free survival not significant), vaginal brachytherapy (overall survival HR 0.35, p<0.001; progression-free survival HR 0.42, p=0.003), and brachytherapy + chemotherapy (overall survival HR 0.30 p=0.002; progression-free survival HR 0.35, p=0.006). Compared with vaginal brachytherapy alone, external beam radiation or the addition of chemotherapy did not further improve progression-free survival (p=0.80, p=0.65, respectively) or overall survival (p=0.47, p=0.74, respectively). CONCLUSION: Adjuvant therapy improves both progression-free survival and overall survival in women with early-stage endometrial cancer meeting high-intermediate risk criteria with lymphovascular space invasion. External beam radiation or adding chemotherapy did not confer additional survival advantage compared with vaginal brachytherapy alone.

Adjuvant therapy for early stage, endometrial cancer with lymphovascular space invasion: Is there a role for chemotherapy?

OBJECTIVES: Lymphovascular space invasion (LVSI) is an independent risk factor for recurrence and poor survival in early-stage endometrioid endometrial cancer (EEC), but optimal adjuvant treatment is unknown. We aimed to compare the survival of women with early-stage EEC with LVSI treated postoperatively with observation (OBS), radiation (RAD, external beam and/or vaginal brachytherapy), or chemotherapy (CHEMO)+/-RAD. METHODS: This was a multi-institutional, retrospective cohort study of women with stage I or II EEC with LVSI who underwent hysterectomy+/-lymphadenectomy from 2005 to 2015 and received OBS, RAD, or CHEMO+/-RAD postoperatively. Progression-free survival and overall survival were evaluated using Kaplan-Meier estimates and Cox proportional hazards models. RESULTS: In total, 478 women were included; median age was 64 years, median follow-up was 50.3 months. After surgery, 143 (30%) underwent OBS, 232 (48.5%) received RAD, and 103(21.5%) received CHEMO+/-RAD (95% of whom received RAD). Demographics were similar among groups, but those undergoing OBS had lower stage and grade. A total of 101 (21%) women recurred. Progression-free survival (PFS) was improved in both CHEMO+/-RAD (HR = 0.18, 95% CI: 0.09-0.39) and RAD (HR = 0.31, 95% CI: 0.18-0.54) groups compared to OBS, though neither adjuvant therapy was superior to the other. However, in grade 3 tumors, the CHEMO+/-RAD group had superior PFS compared to both RAD (HR 0.25; 95% CI: 0.12-0.52) and OBS cohorts (HR = 0.10, 95% CI: 0.03-0.32). Overall survival did not differ by treatment. CONCLUSIONS: In early-stage EEC with LVSI, adjuvant therapy improved PFS compared to observation alone. In those with grade 3 EEC, adjuvant chemotherapy with or without radiation improved PFS compared to observation or radiation alone.

Emergency Department Patients are Receptive to Prayer-Based Interventions to Reduce Alcohol Use.

Previous studies show that elements of spirituality, including prayer and religious services, may contribute to reductions in harmful alcohol use. The objective of this study was to assess the acceptability of prayer as a component of emergency department (ED) interventions for risky alcohol use. A 12-question multiple-choice questionnaire was developed, piloted, and refined by the study team. The questionnaire included questions about current beliefs and attitudes toward prayer and assessed interest in various means of delivering prayer or prayer support for reducing alcohol use. The questionnaire was administered to a consecutive sample of 111 patients recruited from the 12-month follow-up of a parent RCT study on reducing alcohol use among injured ED patients (ReDIAL). To qualify for the parent study, participants needed an ASSIST v3.0 alcohol score ≥ 11. 90 participants (81%) consented to answer questions about prayer. The participating sample was 38% female and 29% nonwhite; mean age was 36 years. Of these participants, 64% reported that they currently pray; of those, 88% reported praying daily or weekly; 79% agreed that prayer helps with coping in difficult times; 68% agreed that prayer could assist in achieving difficult goals; and 48% agreed that prayer helps reduce alcohol use. Interest in various means of utilizing prayer to reduce alcohol use was assessed in all participants (regardless of whether they currently prayed or not): 45% were interested in having others pray for them to reduce alcohol use; 40% were interested in receiving text reminders to pray; 42% were interested in receiving text messages with specific prayers to use; and 47% were interested in receiving text messages that someone was praying for them. 33.3% of the entire sample stated that they would attend services if provided information on spiritual or religious groups in the community. The incorporation of prayer in alcohol interventions was considered acceptable by a proportion of our sample of risky alcohol users, even those who do not currently use prayer as a resource in their lives. Given the promising data on ED patients' perceptions of the significance and acceptability of spiritual practices in reducing alcohol use, prayer may emerge as a useful adjunctive tool in future ED interventions for alcohol use disorders.

Cervical Cancer Screening Access, Outcomes, and Prevalence of Dysplasia in Correctional Facilities: A Systematic Review.

Background: Incarcerated women often access health care primarily through contact with correctional systems. Cervical cancer screening within the correctional system can address the preventable outcome of cervical dysplasia and cancer in this high-risk population. Materials and Methods: A search of PubMed, EMBASE, CINAHL, and ClinicalTrials.gov was conducted for articles published between January, 1966 and December, 2018. All studies on a population of jailed or incarcerated females and at least one of the following outcomes: cervical cancer or dysplasia, pap smear screening, knowledge about screening, treatment of cervical dysplasia, and compliance with follow-up were analyzed. Results: Forty-two studies met inclusion criteria. All 21 studies with prevalence outcomes described a higher prevalence of cervical dysplasia and cancer in the women involved with corrections, compared to a variety of different sources that served as community control groups. The data on screening outcomes were inconsistent. Follow-up compliance for abnormal results was poor, with a study finding that only 21% of women were rescreened within 6 months of the recommended time period. Knowledge about cervical cancer and screening was evaluated in eight studies and was poor across all studies. Conclusion: Women involved in correctional systems have a higher prevalence of cervical dysplasia and cancer than women in the general population. Acceptance of screening varies, and no published interventions have been shown to improve screening within the prison system. Treatment and compliance with follow-up recommendations are extremely poor and should be a focus of future research.

Detailed longitudinal sampling of glioma stem cells in situ reveals Chr7 gain and Chr10 loss as repeated events in primary tumor formation and recurrence.

Intratumoral heterogeneity at the genetic, epigenetic, transcriptomic, and morphologic levels is a commonly observed phenomenon in many aggressive cancer types. Clonal evolution during tumor formation and in response to therapeutic intervention can be predicted utilizing reverse engineering approaches on detailed genomic snapshots of heterogeneous patient tumor samples. In this study, we developed an extensive dataset for a GBM case via the generation of polyclonal and monoclonal glioma stem cell lines from initial diagnosis, and from multiple sections of distant tumor locations of the deceased patient's brain following tumor recurrence. Our analyses revealed the tissue-wide expansion of a new clone in the recurrent tumor and chromosome 7 gain and chromosome 10 loss as repeated genomic events in primary and recurrent disease. Moreover, chromosome 7 gain and chromosome 10 loss produced similar alterations in mRNA expression profiles in primary and recurrent tumors despite possessing other highly heterogeneous and divergent genomic alterations between the tumors. We identified ETV1 and CDK6 as putative candidate genes, and NFKB (complex), IL1B, IL6, Akt and VEGF as potential signaling regulators, as potentially central downstream effectors of chr7 gain and chr10 loss. Finally, the differences caused by the transcriptomic shift following gain of chromosome 7 and loss of chromosome 10 were consistent with those generally seen in GBM samples compared to normal brain in large-scale patient-tumor data sets.

A Core Regulatory Circuit in Glioblastoma Stem Cells Links MAPK Activation to a Transcriptional Program of Neural Stem Cell Identity.

Glioblastoma, the most common primary malignant brain tumor, harbors a small population of tumor initiating cells (glioblastoma stem cells) that have many properties similar to neural stem cells. To investigate common regulatory networks in both neural and glioblastoma stem cells, we subjected both cell types to in-vitro differentiation conditions and measured global gene-expression changes using gene expression microarrays. Analysis of enriched transcription factor DNA-binding sites in the promoters of differentially expressed genes was used to reconstruct regulatory networks involved in differentiation. Computational predictions, which were biochemically validated, show an extensive overlap of regulatory circuitry between cell types including a network centered on the transcription factor KLF4. We further demonstrate that EGR1, a transcription factor previously shown to be downstream of the MAPK pathway, regulates KLF4 expression and that KLF4 in turn transcriptionally activates NOTCH as well as SOX2. These results demonstrate how known genomic alterations in glioma that induce constitutive activation of MAPK are transcriptionally linked to master regulators essential for neural stem cell identify.

Inositol Polyphosphate-5-Phosphatase F (INPP5F) inhibits STAT3 activity and suppresses gliomas tumorigenicity.

Glioblastoma (GBM), the most common type of primary malignant brain tumors harboring a subpopulation of stem-like cells (GSCs), is a fast-growing and often fatal tumor. Signal Transducer and Activator of Transcription 3 (STAT3) is one of the major signaling pathways in GSCs maintenance but the molecular mechanisms underlying STAT3 deregulation in GSCs are poorly defined. Here, we demonstrate that Inositol Polyphosphate-5-Phosphatase F (INPP5F), one of the polyphosphoinositide phosphatases, is differentially expressed in GSCs from glioma patients, and is identified as an inhibitor of STAT3 signaling via interaction with STAT3 and inhibition of its phosphorylation. Constitutively expressed INPP5F showed to suppress self-renewal and proliferation potentials of glioblastoma cells and reduced tumorigenicity of glioblastoma. In addition, loss of INPP5F gene in gliomas is significantly correlated with lower overall patient survivals. These findings suggest that INPP5F is a potential tumor suppressor in gliomas via inhibition of STAT3 pathway, and that deregulation of INPP5F may lead to contribution to gliomagenesis.

Identification of molecular pathways facilitating glioma cell invasion in situ.

Gliomas are mostly incurable secondary to their diffuse infiltrative nature. Thus, specific therapeutic targeting of invasive glioma cells is an attractive concept. As cells exit the tumor mass and infiltrate brain parenchyma, they closely interact with a changing micro-environmental landscape that sustains tumor cell invasion. In this study, we used a unique microarray profiling approach on a human glioma stem cell (GSC) xenograft model to explore gene expression changes in situ in Invading Glioma Cells (IGCs) compared to tumor core, as well as changes in host cells residing within the infiltrated microenvironment relative to the unaffected cortex. IGCs were found to have reduced expression of genes within the extracellular matrix compartment, and genes involved in cell adhesion, cell polarity and epithelial to mesenchymal transition (EMT) processes. The infiltrated microenvironment showed activation of wound repair and tissue remodeling networks. We confirmed by protein analysis the downregulation of EMT and polarity related genes such as CD44 and PARD3 in IGCs, and EFNB3, a tissue-remodeling agent enriched at the infiltrated microenvironment. OLIG2, a proliferation regulator and glioma progenitor cell marker upregulated in IGCs was found to function in enhancing migration and stemness of GSCs. Overall, our results unveiled a more comprehensive picture of the complex and dynamic cell autonomous and tumor-host interactive pathways of glioma invasion than has been previously demonstrated. This suggests targeting of multiple pathways at the junction of invading tumor and microenvironment as a viable option for glioma therapy.

Micro-environment causes reversible changes in DNA methylation and mRNA expression profiles in patient-derived glioma stem cells.

In vitro and in vivo models are widely used in cancer research. Characterizing the similarities and differences between a patient's tumor and corresponding in vitro and in vivo models is important for understanding the potential clinical relevance of experimental data generated with these models. Towards this aim, we analyzed the genomic aberrations, DNA methylation and transcriptome profiles of five parental tumors and their matched in vitro isolated glioma stem cell (GSC) lines and xenografts generated from these same GSCs using high-resolution platforms. We observed that the methylation and transcriptome profiles of in vitro GSCs were significantly different from their corresponding xenografts, which were actually more similar to their original parental tumors. This points to the potentially critical role of the brain microenvironment in influencing methylation and transcriptional patterns of GSCs. Consistent with this possibility, ex vivo cultured GSCs isolated from xenografts showed a tendency to return to their initial in vitro states even after a short time in culture, supporting a rapid dynamic adaptation to the in vitro microenvironment. These results show that methylation and transcriptome profiles are highly dependent on the microenvironment and growth in orthotopic sites partially reverse the changes caused by in vitro culturing.

G-cimp status prediction of glioblastoma samples using mRNA expression data.

Glioblastoma Multiforme (GBM) is a tumor with high mortality and no known cure. The dramatic molecular and clinical heterogeneity seen in this tumor has led to attempts to define genetically similar subgroups of GBM with the hope of developing tumor specific therapies targeted to the unique biology within each of these subgroups. Recently, a subset of relatively favorable prognosis GBMs has been identified. These glioma CpG island methylator phenotype, or G-CIMP tumors, have distinct genomic copy number aberrations, DNA methylation patterns, and (mRNA) expression profiles compared to other GBMs. While the standard method for identifying G-CIMP tumors is based on genome-wide DNA methylation data, such data is often not available compared to the more widely available gene expression data. In this study, we have developed and evaluated a method to predict the G-CIMP status of GBM samples based solely on gene expression data.

Prediction of Associations between microRNAs and Gene Expression in Glioma Biology.

Despite progress in the determination of miR interactions, their regulatory role in cancer is only beginning to be unraveled. Utilizing gene expression data from 27 glioblastoma samples we found that the mere knowledge of physical interactions between specific mRNAs and miRs can be used to determine associated regulatory interactions, allowing us to identify 626 associated interactions, involving 128 miRs that putatively modulate the expression of 246 mRNAs. Experimentally determining the expression of miRs, we found an over-representation of over(under)-expressed miRs with various predicted mRNA target sequences. Such significantly associated miRs that putatively bind over-expressed genes strongly tend to have binding sites nearby the 3'UTR of the corresponding mRNAs, suggesting that the presence of the miRs near the translation stop site may be a factor in their regulatory ability. Our analysis predicted a significant association between miR-128 and the protein kinase WEE1, which we subsequently validated experimentally by showing that the over-expression of the naturally under-expressed miR-128 in glioma cells resulted in the inhibition of WEE1 in glioblastoma cells.

Investigating the genome diversity of B. cereus and evolutionary aspects of B. anthracis emergence.

Here we report the use of a multi-genome DNA microarray to investigate the genome diversity of Bacillus cereus group members and elucidate the events associated with the emergence of Bacillus anthracis the causative agent of anthrax-a lethal zoonotic disease. We initially performed directed genome sequencing of seven diverse B. cereus strains to identify novel sequences encoded in those genomes. The novel genes identified, combined with those publicly available, allowed the design of a "species" DNA microarray. Comparative genomic hybridization analyses of 41 strains indicate that substantial heterogeneity exists with respect to the genes comprising functional role categories. While the acquisition of the plasmid-encoded pathogenicity island (pXO1) and capsule genes (pXO2) represents a crucial landmark dictating the emergence of B. anthracis, the evolution of this species and its close relatives was associated with an overall shift in the fraction of genes devoted to energy metabolism, cellular processes, transport, as well as virulence.

Predicting in vitro drug sensitivity using Random Forests.

MOTIVATION: Panels of cell lines such as the NCI-60 have long been used to test drug candidates for their ability to inhibit proliferation. Predictive models of in vitro drug sensitivity have previously been constructed using gene expression signatures generated from gene expression microarrays. These statistical models allow the prediction of drug response for cell lines not in the original NCI-60. We improve on existing techniques by developing a novel multistep algorithm that builds regression models of drug response using Random Forest, an ensemble approach based on classification and regression trees (CART). RESULTS: This method proved successful in predicting drug response for both a panel of 19 Breast Cancer and 7 Glioma cell lines, outperformed other methods based on differential gene expression, and has general utility for any application that seeks to relate gene expression data to a continuous output variable. IMPLEMENTATION: Software was written in the R language and will be available together with associated gene expression and drug response data as the package ivDrug at http://r-forge.r-project.org.

Gene pathways and subnetworks distinguish between major glioma subtypes and elucidate potential underlying biology.

Molecular diagnostic tools are increasingly being used in an attempt to classify primary human brain tumors more accurately. While methods that are based on the analysis of individual gene expression prove to be useful for diagnostic purposes, they are devoid of biological significance since tumorgenesis is a concerted deregulation of multiple pathways rather than single genes. In a proof of concept, we utilize two large clinical data sets and show that the elucidation of enriched pathways and small differentially expressed sub-networks of protein interactions allow a reliable classification of glioblastomas and oligodendrogliomas. Applying a feature selection method, we observe that an optimized subset of pathways and subnetworks significantly improves the prediction accuracy. By determining the enrichment of altered genes in pathways and subnetworks we show that optimized subsets of genes rarely seem to be a target of genomic alteration. Our results suggest that groups of genes play a decisive role for the phenotype of the underlying tumor samples that can be utilized to reliably distinguish tumor types. In the absence of enrichment of genes that are genomically altered we assume that genetic changes largely exert an indirect rather than direct regulatory influence on a number of tumor-defining regulatory networks.

Unsupervised analysis of transcriptomic profiles reveals six glioma subtypes.

Gliomas are the most common type of primary brain tumors in adults and a significant cause of cancer-related mortality. Defining glioma subtypes based on objective genetic and molecular signatures may allow for a more rational, patient-specific approach to therapy in the future. Classifications based on gene expression data have been attempted in the past with varying success and with only some concordance between studies, possibly due to inherent bias that can be introduced through the use of analytic methodologies that make a priori selection of genes before classification. To overcome this potential source of bias, we have applied two unsupervised machine learning methods to genome-wide gene expression profiles of 159 gliomas, thereby establishing a robust glioma classification model relying only on the molecular data. The model predicts for two major groups of gliomas (oligodendroglioma-rich and glioblastoma-rich groups) separable into six hierarchically nested subtypes. We then identified six sets of classifiers that can be used to assign any given glioma to the corresponding subtype and validated these classifiers using both internal (189 additional independent samples) and two external data sets (341 patients). Application of the classification system to the external glioma data sets allowed us to identify previously unrecognized prognostic groups within previously published data and within The Cancer Genome Atlas glioblastoma samples and the different biological pathways associated with the different glioma subtypes offering a potential clue to the pathogenesis and possibly therapeutic targets for tumors within each subtype.

Correlation analysis between single-nucleotide polymorphism and expression arrays in gliomas identifies potentially relevant target genes.

Primary brain tumors are a major cause of cancer mortality in the United States. Therapy for gliomas, the most common type of primary brain tumors, remains suboptimal. The development of improved therapeutics will require greater knowledge of the biology of gliomas at both the genomic and transcriptional levels. We have previously reported whole genome profiling of chromosome copy number alterations (CNA) in gliomas, and now present our findings on how those changes may affect transcription of genes that may be involved in tumor induction and progression. By calculating correlation values of mRNA expression versus DNA copy number average in a moving window around a given RNA probe set, biologically relevant information can be gained that is obscured by the analysis of a single data type. Correlation coefficients ranged from -0.6 to 0.7, highly significant when compared with previous studies. Most correlated genes are located on chromosomes 1, 7, 9, 10, 13, 14, 19, 20, and 22, chromosomes known to have genomic alterations in gliomas. Additionally, we were able to identify CNAs whose gene expression correlation suggests possible epigenetic regulation. This analysis revealed a number of interesting candidates such as CXCL12, PTER, and LRRN6C, among others. The results have been verified using real-time PCR and methylation sequencing assays. These data will further help differentiate genes involved in the induction and/or maintenance of the tumorigenic process from those that are mere passenger mutations, thereby enriching for a population of potentially new therapeutic molecular targets.

Epigenetic-mediated dysfunction of the bone morphogenetic protein pathway inhibits differentiation of glioblastoma-initiating cells.

Despite similarities between tumor-initiating cells with stem-like properties (TICs) and normal neural stem cells, we hypothesized that there may be differences in their differentiation potentials. We now demonstrate that both bone morphogenetic protein (BMP)-mediated and ciliary neurotrophic factor (CNTF)-mediated Jak/STAT-dependent astroglial differentiation is impaired due to EZH2-dependent epigenetic silencing of BMP receptor 1B (BMPR1B) in a subset of glioblastoma TICs. Forced expression of BMPR1B either by transgene expression or demethylation of the promoter restores their differentiation capabilities and induces loss of their tumorigenicity. We propose that deregulation of the BMP developmental pathway in a subset of glioblastoma TICs contributes to their tumorigenicity both by desensitizing TICs to normal differentiation cues and by converting otherwise cytostatic signals to proproliferative signals.

Genomic changes and gene expression profiles reveal that established glioma cell lines are poorly representative of primary human gliomas.

Genetic aberrations, such as gene amplification, deletions, and loss of heterozygosity, are hallmarks of cancer and are thought to be major contributors to the neoplastic process. Established cancer cell lines have been the primary in vitro and in vivo models for cancer for more than 2 decades; however, few such cell lines have been extensively characterized at the genomic level. Here, we present a high-resolution genome-wide chromosomal alteration and gene expression analyses of five of the most commonly used glioma cell lines and compare the findings with those observed in 83 primary human gliomas. Although genomic alterations known to occur in primary tumors were identified in the cell lines, we also observed several novel recurrent aberrations in the glioma cell lines that are not frequently represented in primary tumors. Additionally, a global gene expression cluster distinct from primary tumors was identified in the glioma cell lines. Our results indicate that established cell lines are generally a poor representation of primary tumor biology, presenting a host of genomic and gene expression changes not observed in primary tissues, although some discrete features of glioma biology were conserved in the established cell lines. Refined maps of genetic alterations and transcriptional divergence from the original tumor type, such as the one presented here, may help serve as a guideline for a more biologically rational and clinically relevant selection of the most appropriate glioma model for a given experiment.