Gene Summary

Gene:DONSON; downstream neighbor of SON
Aliases: B17, C21orf60
Summary:This gene lies downstream of the SON gene and spans 10 kb on chromosome 21. The function of this gene is unknown. [provided by RefSeq, Jul 2008]
Databases:VEGA, OMIM, HGNC, Ensembl, GeneCard, Gene
Protein:protein downstream neighbor of Son
Source:NCBIAccessed: 13 March, 2017


What does this gene/protein do?
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Cancer Overview

Research Indicators

Publications Per Year (1992-2017)
Graph generated 13 March 2017 using data from PubMed using criteria.

Literature Analysis

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Tag cloud generated 13 March, 2017 using data from PubMed, MeSH and CancerIndex

Specific Cancers (7)

Latest Publications: DONSON (cancer-related)

Kleinschmidt-DeMasters BK, Donson AM, Richmond AM, et al.
SOX10 Distinguishes Pilocytic and Pilomyxoid Astrocytomas From Ependymomas but Shows No Differences in Expression Level in Ependymomas From Infants Versus Older Children or Among Molecular Subgroups.
J Neuropathol Exp Neurol. 2016; 75(4):295-8 [PubMed] Article available free on PMC after 01/04/2017 Related Publications
SOX10 is important in nonneoplastic oligodendroglial development, but mRNA transcripts and protein expression are identified in a wider variety of CNS glial neoplasms than oligodendrogliomas. We previously demonstrated high levels of SOX10 mRNA and protein in pilocytic astrocytomas (PAs) but not ependymomas (EPNs). We now extend these studies to investigate subsets of these 2 tumors that affect infants, pilomyxoid astrocytomas (PMAs) and infant (<1 year) ependymomas (iEPNs). By gene expression microarray analysis, we found that iEPNs and all EPNs in older children showed very low SOX10 expression levels, on average 7.1-fold below normal control tissues. EPN groups showed no significant difference in SOX10 expression between iEPN and EPN. PAs/PMAs had 24.1/29.4-fold higher transcript levels, respectively, than those in normal tissues. Using immunohistochemical analysis of adult, pediatric, and infantile EPNs and of PAs/PMAs, we found that EPNs from multiple anatomical locations and both age groups (n = 228) never showed 3+ diffuse nuclear immunostaining for SOX10; the majority were scored at 0 or 1+. Conversely, almost all pediatric and adult PAs and PMAs (n = 47) were scored as 3+. These results suggest that in select settings, SOX10 immunohistochemistry can supplement the diagnosis of PMA and PA and aid in distinguishing them from EPNs.

Matheson CJ, Venkataraman S, Amani V, et al.
A WEE1 Inhibitor Analog of AZD1775 Maintains Synergy with Cisplatin and Demonstrates Reduced Single-Agent Cytotoxicity in Medulloblastoma Cells.
ACS Chem Biol. 2016; 11(4):921-30 [PubMed] Related Publications
The current treatment for medulloblastoma includes surgical resection, radiation, and cytotoxic chemotherapy. Although this approach has improved survival rates, the high doses of chemotherapy required for clinical efficacy often result in lasting neurocognitive defects and other adverse events. Therefore, the development of chemosensitizing agents that allow dose reductions of cytotoxic agents, limiting their adverse effects but maintaining their clinical efficacy, would be an attractive approach to treat medulloblastoma. We previously identified WEE1 kinase as a new molecular target for medulloblastoma from an integrated genomic analysis of gene expression and a kinome-wide siRNA screen of medulloblastoma cells and tissue. In addition, we demonstrated that WEE1 prevents DNA damage-induced cell death by cisplatin and that the WEE1 inhibitor AZD1775 displays synergistic activity with cisplatin. AZD1775 was developed as a WEE1 inhibitor from an initial hit from a high-throughput screen. However, given the lack of structure-activity data for AZD1775, we developed a small series of analogs to determine the requirements for WEE1 inhibition and further examine the effects of WEE1 inhibition in medulloblastoma. Interestingly, the compounds that inhibited WEE1 in the same nanomolar range as AZD1775 had significantly reduced single-agent cytotoxicity compared with AZD1775 and displayed synergistic activity with cisplatin in medulloblastoma cells. The potent cytotoxicity of AZD1775, unrelated to WEE1 inhibition, may result in dose-limiting toxicities and exacerbate adverse effects; therefore, WEE1 inhibitors that demonstrate low cytotoxicity could be dosed at higher concentrations to chemosensitize the tumor and potentiate the effect of DNA-damaging agents such as cisplatin.

Gump JM, Donson AM, Birks DK, et al.
Identification of targets for rational pharmacological therapy in childhood craniopharyngioma.
Acta Neuropathol Commun. 2015; 3:30 [PubMed] Article available free on PMC after 01/04/2017 Related Publications
INTRODUCTION: Pediatric adamantinomatous craniopharyngioma (ACP) is a histologically benign but clinically aggressive brain tumor that arises from the sellar/suprasellar region. Despite a high survival rate with current surgical and radiation therapy (75-95 % at 10 years), ACP is associated with debilitating visual, endocrine, neurocognitive and psychological morbidity, resulting in excheptionally poor quality of life for survivors. Identification of an effective pharmacological therapy could drastically decrease morbidity and improve long term outcomes for children with ACP.
RESULTS: Using mRNA microarray gene expression analysis of 15 ACP patient samples, we have found several pharmaceutical targets that are significantly and consistently overexpressed in our panel of ACP relative to other pediatric brain tumors, pituitary tumors, normal pituitary and normal brain tissue. Among the most highly expressed are several targets of the kinase inhibitor dasatinib - LCK, EPHA2 and SRC; EGFR pathway targets - AREG, EGFR and ERBB3; and other potentially actionable cancer targets - SHH, MMP9 and MMP12. We confirm by western blot that a subset of these targets is highly expressed in ACP primary tumor samples.
CONCLUSIONS: We report here the first published transcriptome for ACP and the identification of targets for rational therapy. Experimental drugs targeting each of these gene products are currently being tested clinically and pre-clinically for the treatment of other tumor types. This study provides a rationale for further pre-clinical and clinical studies of novel pharmacological treatments for ACP. Development of mouse and cell culture models for ACP will further enable the translation of these targets from the lab to the clinic, potentially ushering in a new era in the treatment of ACP.

Griesinger AM, Josephson RJ, Donson AM, et al.
Interleukin-6/STAT3 Pathway Signaling Drives an Inflammatory Phenotype in Group A Ependymoma.
Cancer Immunol Res. 2015; 3(10):1165-74 [PubMed] Article available free on PMC after 01/04/2017 Related Publications
Ependymoma (EPN) in childhood is a brain tumor with substantial mortality. Inflammatory response has been identified as a molecular signature of high-risk Group A EPN. To better understand the biology of this phenotype and aid therapeutic development, transcriptomic data from Group A and B EPN patient tumor samples, and additional malignant and normal brain data, were analyzed to identify the mechanism underlying EPN Group A inflammation. Enrichment of IL6 and STAT3 pathway genes were found to distinguish Group A EPN from Group B EPN and other brain tumors, implicating an IL6 activation of STAT3 mechanism. EPN tumor cell growth was shown to be dependent on STAT3 activity, as demonstrated using shRNA knockdown and pharmacologic inhibition of STAT3 that blocked proliferation and induced apoptosis. The inflammatory factors secreted by EPN tumor cells were shown to reprogram myeloid cells, and this paracrine effect was characterized by a significant increase in pSTAT3 and IL8 secretion. Myeloid polarization was shown to be dependent on tumor secretion of IL6, and these effects could be reversed using IL6-neutralizing antibody or IL6 receptor-targeted therapeutic antibody tocilizumab. Polarized myeloid cell production of IL8 drove unpolarized myeloid cells to upregulate CD163 and to produce a number of proinflammatory cytokines. Collectively, these findings indicate that constitutive IL6/STAT3 pathway activation is important in driving tumor growth and inflammatory cross-talk with myeloid cells within the Group A EPN microenvironment. Effective design of Group A-targeted therapy for children with EPN may require reversal of this potentially immunosuppressive and protumor pathway.

Pajtler KW, Witt H, Sill M, et al.
Molecular Classification of Ependymal Tumors across All CNS Compartments, Histopathological Grades, and Age Groups.
Cancer Cell. 2015; 27(5):728-43 [PubMed] Article available free on PMC after 01/04/2017 Related Publications
Ependymal tumors across age groups are currently classified and graded solely by histopathology. It is, however, commonly accepted that this classification scheme has limited clinical utility based on its lack of reproducibility in predicting patients' outcome. We aimed at establishing a uniform molecular classification using DNA methylation profiling. Nine molecular subgroups were identified in a large cohort of 500 tumors, 3 in each anatomical compartment of the CNS, spine, posterior fossa, supratentorial. Two supratentorial subgroups are characterized by prototypic fusion genes involving RELA and YAP1, respectively. Regarding clinical associations, the molecular classification proposed herein outperforms the current histopathological classification and thus might serve as a basis for the next World Health Organization classification of CNS tumors.

Mafune A, Hama T, Suda T, et al.
Homozygous deletions of UGT2B17 modifies effects of smoking on TP53-mutations and relapse of head and neck carcinoma.
BMC Cancer. 2015; 15:205 [PubMed] Article available free on PMC after 01/04/2017 Related Publications
BACKGROUND: Smoking induces oncogenic TP53-mutations in head and neck squamous cell carcinomas (HNSCCs). Disruptive mutations of TP53-gene and expression of p16 protein [p16 (+)] in tumor tissue associate with worse and better prognosis, respectively. UDP-glucuronosyltransferase 2 family, polypeptide B17 (UGT2B17) detoxifies smoking-related metabolites. Differences among ethnic groups in UGT2B17 are extremely high. Homozygous deletions of UGT2B17 gene (UGT2B17-deletion) are a common copy number variant (CNV) among Japanese, but not a common CNV among Africans and Europeans. Thus, we examined Japanese patients with HNSCC to explore if UGT2B17-deletion and/or p16 (+) modify effects of smoking on TP53-mutations and affect relapse.
METHODS: We conducted a posthoc analysis of a prospective cohort. Polymerase chain reaction, immunohistochemistry, and direct sequencing were used to determine UGT2B17-deletion, p16 (+), and detailed TP53-mutations, respectively.
RESULTS: UGT2B17-deletion was observed in 80% of this study population. For this 80%, TP53-mutations were significantly more common among smokers than non-smokers (P = 0.0016), but this difference between smokers and nonsmokers was not significant for the 20% with UGT2B17. In patients with UGT2B17-deletion and p16 (+), simultaneously, TP53-mutations were much more common among smokers than among non-smokers (81% versus 17%; P = 0.0050). Patients with both UGT2B17-deletion and disruptive TP53-mutations had higher relapse rates than other patients (hazard ratio, 2.22; 95% confidence interval, 1.30 to 3.80, P = 0.004) in a stepwise method.
CONCLUSIONS: These results suggest that UGT2B17-deletion interacting with p16 (+) may modify effects of smoking on TP53-mutations and may further interact with the disruptive TP53-mutations to raise relapse rates among Japanese patients with HNSCC.

Tanskanen T, Gylfe AE, Katainen R, et al.
Systematic search for rare variants in Finnish early-onset colorectal cancer patients.
Cancer Genet. 2015 Jan-Feb; 208(1-2):35-40 [PubMed] Related Publications
The heritability of colorectal cancer (CRC) is incompletely understood, and the contribution of undiscovered rare variants may be important. In search of rare disease-causing variants, we exome sequenced 22 CRC patients who were diagnosed before the age of 40 years. Exome sequencing data from 95 familial CRC patients were available as a validation set. Cases with known CRC syndromes were excluded. All patients were from Finland, a country known for its genetically homogenous population. We searched for rare nonsynonymous variants with allele frequencies below 0.1% in 3,374 Finnish and 58,112 non-Finnish controls. In addition, homozygous and compound heterozygous variants were studied. No genes with rare loss-of-function variants were present in more than one early-onset CRC patient. Three genes (ADAMTS4, CYTL1, and SYNE1) harbored rare loss-of-function variants in both early-onset and familial CRC cases. Five genes with homozygous variants in early-onset CRC cases were found (MCTP2, ARHGAP12, ATM, DONSON, and ROS1), including one gene (MCTP2) with a homozygous splice site variant. All discovered homozygous variants were exclusive to one early-onset CRC case. Independent replication is required to associate the discovered variants with CRC. These findings, together with a lack of family history in 19 of 22 (86%) early-onset patients, suggest genetic heterogeneity in unexplained early-onset CRC patients, thus emphasizing the requirement for large sample sizes and careful study designs to elucidate the role of rare variants in CRC susceptibility.

Xiang C, Wang J, Kou X, et al.
Pulmonary expression of CYP2A13 and ABCB1 is regulated by FOXA2, and their genetic interaction is associated with lung cancer.
FASEB J. 2015; 29(5):1986-98 [PubMed] Related Publications
Inhaled xenobiotics such as tobacco-specific carcinogen 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone are mainly metabolized by phase I oxidase cytochrome P450, family 2, subfamily A, polypeptide 13 (CYP2A13), phase II conjugate UDP glucuronosyltransferase 2 family, polypeptide B17 (UGT2B17), and phase III transporter ATP-binding cassette, subfamily B (MDR/TAP), member 1 (ABCB1), with genetic polymorphisms implicated in lung cancer. Their genetic interaction and pulmonary expression regulation are largely unknown. We analyzed joint association for CYP2A13 and ABCB1 polymorphisms in 2 independent lung cancer case populations (669 and 566 patients) and 1 common control population (749 subjects), and characterized the trans-acting function of the lung development-related transcription factor forkhead box A2 (FOXA2). We undertook FOXA2 overexpression and down-regulation in lung epithelial cell lines, analyzed functional impact on the transactivation of CYP2A13, UGT2B17, and ABCB1, and measured correlation for their expressions in lung tissues. We found a substantial reduction in cancer risk (OR 0.39; 95% CI 0.25-0.61; Pinteraction = 0.029) associated with combined genotypes for CYP2A13 R257C and a functionary regulatory variant in the cis element of ABCB1 synergistically targeted by GATA binding protein 6 and FOXA2. Genetic manipulation of FOXA2 consistently influenced its binding to and transactivation of the promoters of CYP2A13, UGT2B17, and ABCB1, whose mRNA and protein expressions were all consistently correlated with those of FOXA2 in both tumorous and normal lung tissues. We therefore establish FOXA2 as a core transcriptional modulator for pulmonary xenobiotic metabolic pathways and uncover an etiologically relevant interaction between CYP2A13 and ABCB1, furthering our understanding of expression and function of the xenobiotic metabolism system.

Kleinschmidt-DeMasters BK, Donson AM, Vogel H, Foreman NK
Pilomyxoid Astrocytoma (PMA) Shows Significant Differences in Gene Expression vs. Pilocytic Astrocytoma (PA) and Variable Tendency Toward Maturation to PA.
Brain Pathol. 2015; 25(4):429-40 [PubMed] Article available free on PMC after 01/04/2017 Related Publications
Pilomyxoid astrocytomas (PMAs) manifest a more aggressive clinical course than pilocytic astrocytomas (PAs). Development of effective therapies demands a better biological understanding of PMA. We first conducted gene expression microarray analysis of 9 PMA and 13 PA from infra- and supratentorial sites. Unsupervised hierarchical clustering analysis demonstrated that tumors are grouped according to anatomic site, not diagnosis. Gene expression profiles were then contrasted between eight PMAs and six PAs, all supratentorial/hypothalamic/chiasmal. Clinical outcome of PMAs varied, with four out of four patients with diencephalic syndrome succumbing to disease, one of whom showed bulky metastatic leptomeningeal spread at autopsy, with bimodal maturation to PA in some areas and de-differentiation to glioblastoma in others. A surviving child has undergone multiple surgical debulking, with progressive maturation to PA over time. Ontology-enrichment analysis identified overexpression in PMAs of extracellular matrix and mitosis-related genes. Genes overexpressed in PMA vs. PA, ranked according to fold-change, included developmental genes H19, DACT2, extracellular matrix collagens (COL2A1; COL1A1) and IGF2BP3 (IMP3), the latter previously identified as an adverse prognostic factor in PMA and PA.

Buczkowicz P, Hoeman C, Rakopoulos P, et al.
Genomic analysis of diffuse intrinsic pontine gliomas identifies three molecular subgroups and recurrent activating ACVR1 mutations.
Nat Genet. 2014; 46(5):451-6 [PubMed] Article available free on PMC after 01/04/2017 Related Publications
Diffuse intrinsic pontine glioma (DIPG) is a fatal brain cancer that arises in the brainstem of children, with no effective treatment and near 100% fatality. The failure of most therapies can be attributed to the delicate location of these tumors and to the selection of therapies on the basis of assumptions that DIPGs are molecularly similar to adult disease. Recent studies have unraveled the unique genetic makeup of this brain cancer, with nearly 80% found to harbor a p.Lys27Met histone H3.3 or p.Lys27Met histone H3.1 alteration. However, DIPGs are still thought of as one disease, with limited understanding of the genetic drivers of these tumors. To understand what drives DIPGs, we integrated whole-genome sequencing with methylation, expression and copy number profiling, discovering that DIPGs comprise three molecularly distinct subgroups (H3-K27M, silent and MYCN) and uncovering a new recurrent activating mutation affecting the activin receptor gene ACVR1 in 20% of DIPGs. Mutations in ACVR1 were constitutively activating, leading to SMAD phosphorylation and increased expression of the downstream activin signaling targets ID1 and ID2. Our results highlight distinct molecular subgroups and novel therapeutic targets for this incurable pediatric cancer.

Harris PS, Venkataraman S, Alimova I, et al.
Integrated genomic analysis identifies the mitotic checkpoint kinase WEE1 as a novel therapeutic target in medulloblastoma.
Mol Cancer. 2014; 13:72 [PubMed] Article available free on PMC after 01/04/2017 Related Publications
BACKGROUND: Medulloblastoma is the most common type of malignant brain tumor that afflicts children. Although recent advances in chemotherapy and radiation have improved outcomes, high-risk patients do poorly with significant morbidity.
METHODS: To identify new molecular targets, we performed an integrated genomic analysis using structural and functional methods. Gene expression profiling in 16 medulloblastoma patient samples and subsequent gene set enrichment analysis indicated that cell cycle-related kinases were associated with disease development. In addition a kinome-wide small interfering RNA (siRNA) screen was performed to identify kinases that, when inhibited, could prevent cell proliferation. The two genome-scale analyses were combined to identify key vulnerabilities in medulloblastoma. The inhibition of one of the identified targets was further investigated using RNAi and a small molecule inhibitor.
RESULTS: Combining the two analyses revealed that mitosis-related kinases were critical determinants of medulloblastoma cell proliferation. RNA interference (RNAi)-mediated knockdown of WEE1 kinase and other mitotic kinases was sufficient to reduce medulloblastoma cell proliferation. These data prompted us to examine the effects of inhibiting WEE1 by RNAi and by a small molecule inhibitor of WEE1, MK-1775, in medulloblastoma cell lines. MK-1775 inhibited the growth of medulloblastoma cell lines, induced apoptosis and increased DNA damage at nanomolar concentrations. Further, MK-1775 was synergistic with cisplatin in reducing medulloblastoma cell proliferation and resulted in an associated increase in cell death. In vivo MK-1775 suppressed medulloblastoma tumor growth as a single agent.
CONCLUSIONS: Taken together, these findings highlight mitotic kinases and, in particular, WEE1 as a rational therapeutic target for medulloblastoma.

Hoffman LM, Donson AM, Nakachi I, et al.
Molecular sub-group-specific immunophenotypic changes are associated with outcome in recurrent posterior fossa ependymoma.
Acta Neuropathol. 2014; 127(5):731-45 [PubMed] Article available free on PMC after 01/04/2017 Related Publications
Better understanding of ependymoma (EPN) biology at relapse is needed to improve therapy at this critical event. Convincing data exist defining transcriptionally distinct posterior fossa (PF) sub-groups A and B at diagnosis. The clinical and biological consequence of these sub-groups at recurrence has not yet been defined. Genome and transcriptome microarray profiles and clinical variables of matched primary and first recurrent PF EPN pairs were used to identify biologically distinct patterns of progression between EPN sub-groups at recurrence. Key findings were validated by histology and immune function assays. Transcriptomic profiles were partially conserved at recurrence. However, 4 of 14 paired samples changed sub-groups at recurrence, and significant sub-group-specific transcriptomic changes between primary and recurrent tumors were identified, which were predominantly immune-related. Further examination revealed that Group A primary tumors harbor an immune gene signature and cellular functionality consistent with an immunosuppressive phenotype associated with tissue remodeling and wound healing. Conversely, Group B tumors develop an adaptive, antigen-specific immune response signature and increased T-cell infiltration at recurrence. Clinical distinctions between sub-groups become more apparent after first recurrence. Group A tumors were more often sub-totally resected and had a significantly shorter time to subsequent progression and worse overall survival. Minimal tumor-specific genomic changes were observed for either PF Groups A or B at recurrence. Molecular sub-groups of PF EPN convey distinct immunobiologic signatures at diagnosis and recurrence, providing potential biologic rationale to their disparate clinical outcomes. Immunotherapeutic approaches may be warranted, particularly in Group A PF EPN.

Donson AM, Kleinschmidt-DeMasters BK, Aisner DL, et al.
Pediatric brainstem gangliogliomas show BRAF(V600E) mutation in a high percentage of cases.
Brain Pathol. 2014; 24(2):173-83 [PubMed] Article available free on PMC after 01/04/2017 Related Publications
Brainstem gangliogliomas (GGs), often cannot be resected, have a much poorer prognosis than those located in more common supratentorial sites and may benefit from novel therapeutic approaches. Therapeutically targetable BRAF c.1799T>A (p.V600E) (BRAF(V600E) ) mutations are harbored in roughly 50% of collective GGs taken from all anatomical sites. Large numbers of pediatric brainstem GGs, however, have not been specifically assessed and anatomic-and age-restricted assessment of genetic and biological factors are becoming increasingly important. Pediatric brainstem GGs (n = 13), non-brainstem GGs (n = 11) and brainstem pilocytic astrocytomas (PAs) (n = 8) were screened by standard Sanger DNA sequencing of BRAF exon 15. Five of 13 (38%) pediatric GG harbored a definitive BRAF(V600E) mutation, with two others exhibiting an equivocal result by this method. BRAF(V600E) was also seen in five of 11 (45%) non-brainstem GGs and one of eight (13%) brainstem PAs. VE1 immunostaining for BRAF(V600E) showed concordance with sequencing in nine of nine brainstem GGs including the two cases equivocal by Sanger. The equivocal brainstem GGs were subsequently shown to harbor BRAF(V600E) using a novel, more sensitive, RNA-sequencing approach, yielding a final BRAF(V600E) mutation frequency of 54% (seven of 13) in brainstem GGs. BRAF(V600E) -targeted therapeutics should be a consideration for the high percentage of pediatric brainstem GGs refractory to conventional therapies.

Griesinger AM, Birks DK, Donson AM, et al.
Characterization of distinct immunophenotypes across pediatric brain tumor types.
J Immunol. 2013; 191(9):4880-8 [PubMed] Article available free on PMC after 01/04/2017 Related Publications
Despite increasing evidence that antitumor immune control exists in the pediatric brain, these findings have yet to be exploited successfully in the clinic. A barrier to development of immunotherapeutic strategies in pediatric brain tumors is that the immunophenotype of these tumors' microenvironment has not been defined. To address this, the current study used multicolor FACS of disaggregated tumor to systematically characterize the frequency and phenotype of infiltrating immune cells in the most common pediatric brain tumor types. The initial study cohort consisted of 7 pilocytic astrocytoma (PA), 19 ependymoma (EPN), 5 glioblastoma (GBM), 6 medulloblastoma (MED), and 5 nontumor brain (NT) control samples obtained from epilepsy surgery. Immune cell types analyzed included both myeloid and T cell lineages and respective markers of activated or suppressed functional phenotypes. Immune parameters that distinguished each of the tumor types were identified. PA and EPN demonstrated significantly higher infiltrating myeloid and lymphoid cells compared with GBM, MED, or NT. Additionally, PA and EPN conveyed a comparatively activated/classically activated myeloid cell-skewed functional phenotype denoted in particular by HLA-DR and CD64 expression. In contrast, GBM and MED contained progressively fewer infiltrating leukocytes and more muted functional phenotypes similar to that of NT. These findings were recapitulated using whole tumor expression of corresponding immune marker genes in a large gene expression microarray cohort of pediatric brain tumors. The results of this cross-tumor comparative analysis demonstrate that different pediatric brain tumor types exhibit distinct immunophenotypes, implying that specific immunotherapeutic approaches may be most effective for each tumor type.

Barton VN, Donson AM, Birks DK, et al.
Insulin-like growth factor 2 mRNA binding protein 3 expression is an independent prognostic factor in pediatric pilocytic and pilomyxoid astrocytoma.
J Neuropathol Exp Neurol. 2013; 72(5):442-9 [PubMed] Article available free on PMC after 01/04/2017 Related Publications
Prognostic factors in pilocytic astrocytomas (PAs) and pilomyxoid astrocytomas (PMAs) include extent of resection, location, and age, but no molecular markers have been established. Insulin-like growth factor 2 mRNA binding protein 3 (IMP3, IGF2BP3) is predictive of an unfavorable prognosis in other tumors, including high-grade astrocytomas, but its role in PA/PMA is unknown. This study aimed to determine the expression and prognostic value of IMP3 in pediatric PA/PMAs. Insulin-like growth factor 2 mRNA binding protein 3 protein expression was examined by immunohistochemistry in 77 pediatric PAs (n = 70) and PMAs (n = 7) and scored on a subjective scale. Strong diffuse staining for IMP3 was observed in 31% (24 of 77) of tumors and associated with a shorter progression-free survival (hazard ratio, 2.63; p = 0.008). This cohort confirmed previously identified prognostic factors, including extent of resection, age, and tumor location. Currently, only clinical factors are weighed to stratify risk for patients and to identify those who should receive further therapy. Multivariate analyses identified IMP3 expression as an independent prognostic factor when combined with high-/low-risk stratification (hazard ratio, 2.45; p = 0.016). High IMP3, as assessed by immunohistochemistry, has potential use as an additional predictor of poor prognosis in pediatric PA/PMAs and warrants evaluation in larger cohorts.

Birks DK, Donson AM, Patel PR, et al.
Pediatric rhabdoid tumors of kidney and brain show many differences in gene expression but share dysregulation of cell cycle and epigenetic effector genes.
Pediatr Blood Cancer. 2013; 60(7):1095-102 [PubMed] Article available free on PMC after 01/04/2017 Related Publications
BACKGROUND: Rhabdoid tumors (RTs) are aggressive tumors of early childhood that occur most often in brain (AT/RTs) or kidney (KRTs). Regardless of location, they are characterized by loss of functional SMARCB1 protein, a component of the SWI/SNF chromatin remodeling complex. The aim of this study was to determine genes and biological process dysregulated in common to both AT/RTs and KRTs.
PROCEDURE: Gene expression for AT/RTs was compared to that of other brain tumors and normal brain using microarray data from our lab. Similar analysis was performed for KRTs and other kidney tumors and normal kidney using data from GEO. Dysregulated genes common to both analyses were analyzed for functional significance.
RESULTS: Unsupervised hierarchical clustering of RTs identified three major subsets: two comprised of AT/RTs, and one of KRTs. Compared to other tumors, 1,187, 663, and 539 genes were dysregulated in each subset, respectively. Only 14 dysregulated genes were common to all three subsets. Compared to normal tissue, 5,209, 4,275, and 2,841 genes were dysregulated in each subset, with an overlap of 610 dysregulated genes. Among these genes, processes associated with cell proliferation, MYC activation, and epigenetic dysregulation were common to all three RT subsets.
CONCLUSIONS: The low overlap of dysregulated genes in AT/RTs and KRTs suggests that factors in addition to SMARCB1 loss play a role in determining subsequent gene expression. Drugs which target cell cycle or epigenetic genes may be useful in all RTs. Additionally, targeted therapies tailored to specific RT subset molecular profiles should be considered.

Whiteway SL, Harris PS, Venkataraman S, et al.
Inhibition of cyclin-dependent kinase 6 suppresses cell proliferation and enhances radiation sensitivity in medulloblastoma cells.
J Neurooncol. 2013; 111(2):113-21 [PubMed] Article available free on PMC after 01/04/2017 Related Publications
Medulloblastoma accounts for 20 % of all primary pediatric intracranial tumors. Current treatment cures 50-80 % of patients but is associated with significant long-term morbidity and thus new therapeutic targets are needed. One such target is cyclin-dependent kinase 6 (CDK6), a serine/threonine kinase that plays a vital role in cell cycle progression and differentiation. CDK6 is overexpressed in medulloblastoma patients and is associated with an adverse prognosis. To investigate the role of CDK6 in medulloblastoma, we assayed the effect of CDK6 inhibition on proliferation by depleting expression with RNA interference (RNAi) or by inhibiting kinase function with a small molecule inhibitor, PD0332991. Cell proliferation was assessed by colony focus assay or by the xCELLigence system. We then investigated the impact of CDK6 inhibition on differentiation of murine neural stem cells by immunofluorescence of relevant markers. Finally we evaluated the effects of PD0332991 treatment on medulloblastoma cell cycle and radiosensitivity using colony focus assays. Gene expression analysis revealed that CDK6 mRNA expression is higher than normal cerebellum in fifteen out of sixteen medulloblastoma patient samples. Inhibition of CDK6 by RNAi significantly decreased medulloblastoma cell proliferation and colony forming potential. Interestingly, CDK6 inhibition by RNAi increased differentiation in murine neural stem cells. PD0332991 treatment significantly decreased medulloblastoma cell proliferation and led to a G0/G1 cell cycle arrest. Furthermore, PD0332991 pretreatment sensitized medulloblastoma cells to ionizing radiation. Our findings suggest that targeting CDK6 with small molecule inhibitors may prove beneficial in the treatment of medulloblastoma, especially when combined with radiation.

Donson AM, Birks DK, Schittone SA, et al.
Increased immune gene expression and immune cell infiltration in high-grade astrocytoma distinguish long-term from short-term survivors.
J Immunol. 2012; 189(4):1920-7 [PubMed] Article available free on PMC after 01/04/2017 Related Publications
Survival in the majority of high-grade astrocytoma (HGA) patients is very poor, with only a rare population of long-term survivors. A better understanding of the biological factors associated with long-term survival in HGA would aid development of more effective therapy and survival prediction. Factors associated with long-term survival have not been extensively studied using unbiased genome-wide expression analyses. In the current study, gene expression microarray profiles of HGA from long-term survivors were interrogated for discovery of survival-associated biological factors. Ontology analyses revealed that increased expression of immune function-related genes was the predominant biological factor that positively correlated with longer survival. A notable T cell signature was present within this prognostic immune gene set. Using immune cell-specific gene classifiers, both T cell-associated and myeloid linage-associated genes were shown to be enriched in HGA from long-term versus short-term survivors. Association of immune function and cell-specific genes with survival was confirmed independently in a larger publicly available glioblastoma gene expression microarray data set. Histology was used to validate the results of microarray analyses in a larger cohort of long-term survivors of HGA. Multivariate analyses demonstrated that increased immune cell infiltration was a significant independent variable contributing to longer survival, as was Karnofsky/Lansky performance score. These data provide evidence of a prognostic anti-tumor adaptive immune response and rationale for future development of immunotherapy in HGA.

Sufit A, Donson AM, Birks DK, et al.
Diffuse intrinsic pontine tumors: a study of primitive neuroectodermal tumors versus the more common diffuse intrinsic pontine gliomas.
J Neurosurg Pediatr. 2012; 10(2):81-8 [PubMed] Article available free on PMC after 01/04/2017 Related Publications
OBJECT: The diagnosis of diffuse pontine tumors has largely been made on the basis of MRI since the early 1990 s. In cases of tumors considered "typical," as a rule, no biopsy specimen has been obtained, and the tumors have been considered diffuse intrinsic pontine gliomas (DIPGs). There have been sporadic reports that primitive neuroectodermal tumors (PNETs) of the pons may not be distinguishable from the DIPGs by radiological imaging. This study presents 2 cases of diffuse pontine PNETs with molecular evidence that these are indeed PNETs, distinct from DIPGs, thus supporting biopsy of diffuse pontine tumors as a standard of care.
METHODS: Biopsy specimens were obtained from 7 diffuse pontine tumors and snap frozen. Two of these 7 tumors were identified on the basis of pathological examination as PNETs. All 7 of the diffuse pontine tumors were analyzed for gene expression using the Affymetrix HG-U133 Plus 2.0 GeneChip microarray. Gene expression was compared with that of supratentorial PNETs, medulloblastomas, and low- and high-grade gliomas outside the brainstem.
RESULTS: Unsupervised hierarchical clustering analysis of gene expression demonstrated that pontine PNETs are most closely related to PNETs of the supratentorial region and not with gliomas. They do not cluster with the 5 DIPGs in the study. Thirty-eight genes, including GATA3, are uniquely differentially expressed in pontine PNETs compared with other types of pediatric brain tumors, including DIPGs and other PNETs at a false discovery rate statistical significance of less than 0.05.
CONCLUSIONS: The cluster and individual gene expression analyses indicate that pontine PNETs are intrinsically different from DIPGs. The 2 pontine PNET cases cluster with supratentorial PNETs, rather than with DIPGs, suggesting that these tumors should be treated with a PNET regimen, not with DIPG therapy. Since diagnosis by imaging is not reliable and the biology of the tumors is disparate, a biopsy should be performed to enable accurate diagnosis and direct potentially more effective treatments.

Macy ME, Birks DK, Barton VN, et al.
Clinical and molecular characteristics of congenital glioblastoma.
Neuro Oncol. 2012; 14(7):931-41 [PubMed] Article available free on PMC after 01/04/2017 Related Publications
Congenital glioblastoma (cGBM) is an uncommon tumor of infancy with a reported variable but often poor cure rate, even with intensive therapy. Five patients with cGBMs, arising de novo and not in familial tumor predisposition kindreds, were studied for histological and biological features, using Affymetrix microarray. Tumors were large, often associated with hemorrhage, extended into the thalamus, and often bulged into the ventricles. One patient died acutely from bleeding at the time of operation. The 4 surviving patients underwent surgery (1 gross total resection, 3 subtotal resections or biopsies) and moderate intensity chemotherapy without radiation, and remain progression-free at a median time of 36 months (range, 30-110 months). Affymetrix microarrays measured gene expression on the 3 cGBMs from which frozen tissue was available. Unsupervised hierarchical clustering of cGBMs versus 168 other central nervous system tumors demonstrated that cGBMs clustered most closely with other high-grade gliomas. Gene expression profiles of cGBMs were compared with non-congenital pediatric and adult GBMs. cGBMs demonstrated marked similarity to both pediatric and adult GBMs, with only 31 differentially expressed genes identified (false discovery rate, <0.05). Unique molecular features of cGBMs included over-expression of multiple genes involved in glucose metabolism and tissue hypoxia. cGBMs show histological and biological overlap with pediatric and adult GBMs but appear to have a more favorable outcome, with good response to moderate intensity chemotherapy with only subtotal resection or biopsy. Further study may determine whether identified gene expression differences contribute to the improved survival seen in these tumors.

Chan MH, Kleinschmidt-Demasters BK, Donson AM, et al.
Pediatric brainstem gangliogliomas show overexpression of neuropeptide prepronociceptin (PNOC) by microarray and immunohistochemistry.
Pediatr Blood Cancer. 2012; 59(7):1173-9 [PubMed] Article available free on PMC after 01/04/2017 Related Publications
BACKGROUND: Gangliogliomas (GGs) primary to brainstem are rare, with the overwhelming majority of GGs occurring in supratentorial, especially temporal lobe, locations. A less favorable prognosis exists for brainstem GGs, despite their usually identical WHO grade I status. Few large clinical series, and limited biological information, exists on these tumors, especially gene expression.
PROCEDURE: Seven pediatric brainstem GGs, all with classic histological features, seen at our institution since 2000 were identified. Frozen section material was available for gene expression microarray profiling from five of seven brainstem GGs and compared with that from three non-brainstem pediatric GGs.
RESULTS: Significant upregulation of a number of genes was identified, most of which were involved in pathways of neural signaling, embryonic development, and pattern specification in pediatric brainstem GGs compared to non-brainstem. The single largest upregulated gene was a 256-fold increase in the expression of the neuropeptide prepronociceptin (PNOC); the protein product of this gene has been implicated in neuronal growth. Overexpression was validated by Western blot and by immunohistochemistry (IHC). Strong IHC expression of PNOC was seen in neoplastic neurons of 7/7 brainstem GGs, but was significantly weaker in non-brainstem GGs, and completely negative in normal pediatric autopsy brainstem controls.
CONCLUSIONS: PNOC IHC was often superior to IHC for NeuN, synaptophysin, or neurofilament for highlighting neoplastic neurons.

Harris PS, Venkataraman S, Alimova I, et al.
Polo-like kinase 1 (PLK1) inhibition suppresses cell growth and enhances radiation sensitivity in medulloblastoma cells.
BMC Cancer. 2012; 12:80 [PubMed] Article available free on PMC after 01/04/2017 Related Publications
BACKGROUND: Medulloblastoma is the most common malignant brain tumor in children and remains a therapeutic challenge due to its significant therapy-related morbidity. Polo-like kinase 1 (PLK1) is highly expressed in many cancers and regulates critical steps in mitotic progression. Recent studies suggest that targeting PLK1 with small molecule inhibitors is a promising approach to tumor therapy.
METHODS: We examined the expression of PLK1 mRNA in medulloblastoma tumor samples using microarray analysis. The impact of PLK1 on cell proliferation was evaluated by depleting expression with RNA interference (RNAi) or by inhibiting function with the small molecule inhibitor BI 2536. Colony formation studies were performed to examine the impact of BI 2536 on medulloblastoma cell radiosensitivity. In addition, the impact of depleting PLK1 mRNA on tumor-initiating cells was evaluated using tumor sphere assays.
RESULTS: Analysis of gene expression in two independent cohorts revealed that PLK1 mRNA is overexpressed in some, but not all, medulloblastoma patient samples when compared to normal cerebellum. Inhibition of PLK1 by RNAi significantly decreased medulloblastoma cell proliferation and clonogenic potential and increased cell apoptosis. Similarly, a low nanomolar concentration of BI 2536, a small molecule inhibitor of PLK1, potently inhibited cell growth, strongly suppressed the colony-forming ability, and increased cellular apoptosis of medulloblastoma cells. Furthermore, BI 2536 pretreatment sensitized medulloblastoma cells to ionizing radiation. Inhibition of PLK1 impaired tumor sphere formation of medulloblastoma cells and decreased the expression of SRY (sex determining region Y)-box 2 (SOX2) mRNA in tumor spheres indicating a possible role in targeting tumor initiating cells.
CONCLUSIONS: Our data suggest that targeting PLK1 with small molecule inhibitors, in combination with radiation therapy, is a novel strategy in the treatment of medulloblastoma that warrants further investigation.

Venkataraman S, Alimova I, Tello T, et al.
Targeting Aurora Kinase A enhances radiation sensitivity of atypical teratoid rhabdoid tumor cells.
J Neurooncol. 2012; 107(3):517-26 [PubMed] Article available free on PMC after 01/04/2017 Related Publications
Atypical teratoid/rhabdoid tumors (ATRT) are rare, highly malignant, embryonal CNS tumors with a poor prognosis. Therapy relies on highly toxic chemotherapy and radiotherapy. To improve outcomes and decrease morbidity, more targeted therapy is required. Gene expression analysis revealed elevated expression of multiple kinases in ATRT tissues. Aurora Kinase A was one of the candidate kinases. The objective of this study was to evaluate the impact of Aurora Kinase A inhibition in ATRT cell lines. Our analysis revealed that inhibition of Aurora Kinase A induces cell death in ATRT cells and the small molecule inhibitor MLN 8237 sensitizes these cells to radiation. Furthermore, inhibition of Aurora Kinase A resulted in decreased activity of pro-proliferative signaling pathways. These data indicate that inhibition of Aurora Kinase A is a promising small molecule target for ATRT therapy.

Knipstein JA, Birks DK, Donson AM, et al.
Histone deacetylase inhibition decreases proliferation and potentiates the effect of ionizing radiation in atypical teratoid/rhabdoid tumor cells.
Neuro Oncol. 2012; 14(2):175-83 [PubMed] Article available free on PMC after 01/04/2017 Related Publications
Atypical teratoid/rhabdoid tumor (ATRT) is a highly malignant central nervous system neoplasm that primarily occurs in children less than 3 years of age. Because of poor outcomes with intense and toxic multimodality treatment, new therapies are urgently needed. Histone deacetylase inhibitors (HDIs) have been evaluated as novel agents for multiple malignancies and have been shown to function as radiosensitizers. They act as epigenetic modifiers and lead to re-expression of inappropriately repressed genes, proteins, and cellular functions. Because of the underlying chromatin remodeling gene mutation in ATRT, HDIs are ideal candidates for therapeutic evaluation. To evaluate the role of HDIs against ATRT in vitro, we assessed the effect of drug treatment on proliferation, apoptosis, and gene expression. In addition, we examined HDI pretreatment as a radiosensitization strategy for ATRT. 3-(4,5-dimethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl)-2-(4-sulfophenyl)-2H-tetrazolium with phenazine methosulfate electron coupling reagent (MTS) and clonogenic assays demonstrated that HDI treatment significantly reduces the proliferative capacity of BT-12 and BT-16 ATRT cells. In addition, the HDI SNDX-275 was able to induce apoptosis in both cell lines and induced p21(Waf1/Cip1) protein expression as measured by Western blot. Evaluation of differential gene expression by microarray and pathway analysis after HDI treatment demonstrated alterations of several key ATRT cellular functions. Finally, we showed that HDI pretreatment effectively potentiates the effect of ionizing radiation on ATRT cells as measured by clonogenic assay. Our findings suggest that the addition of HDIs to ATRT therapy may prove to be beneficial, especially when administered in combination with current treatment modalities, such as radiation.

Kutikov A, Makhov P, Golovine K, et al.
Interleukin-6: a potential biomarker of resistance to multitargeted receptor tyrosine kinase inhibitors in castration-resistant prostate cancer.
Urology. 2011; 78(4):968.e7-11 [PubMed] Article available free on PMC after 01/04/2017 Related Publications
OBJECTIVE: To determine if cellular interleukin-6 production predicts response to tyrosine kinase inhibitors (TKIs). As clinical experience using TKIs in patients with castration-resistant prostate cancer (CRPC) matures, Phase II trials show a heterogeneous response to sunitinib in CRPC patients. Change in serum prostate-specific antigen (PSA) level has proven unreliable for prediction of CRPC response to TKIs. Interleukin-6 (IL-6), a critical mediator of prostate cancer pathogenesis, has been shown to rise in patients with disease progression. As such, we investigated whether cellular IL-6 production can predict TKI response in both in vitro and in vivo models.
METHODS: IL-6 mRNA levels and protein expression were examined by reverse transcriptase-polymerase chain reaction and enzyme-linked immunosorbent assay, respectively. Apoptosis was examined using the terminal dUTP nick-end labeling assay. For in vivo studies, a CRPC xenograft model in C.B17/Icr-scid mice was used.
RESULTS: PC-3 and DU-145 CRPC cell lines exhibited a heterogeneous response to sunitinib and pazopanib. Dose-dependent reduction of IL-6 was observed in TKI-sensitive DU-145 cells. In contrast, the TKI-resistant PC-3 cells failed to suppress IL-6 secretion. Instead, in the presence of tumor necrosis factor-alpha, IL-6 rose significantly upon administration of TKIs. Findings of in vitro experiments were confirmed in an in vivo mouse model of CRPC.
CONCLUSION: Sensitivity of CRPC cells to TKIs is heterogeneous. These findings are consistent with results of recently published Phase II clinical trials using sunitinib in patients with CRPC. A substantial rise in IL-6 occurs both in vitro and in vivo in the presence of TKIs in resistant PC-3 cells but not in TKI-sensitive DU-145 cells. These findings suggest that IL-6 may represent a biomarker for TKI resistance in patients with CRPC.

Birks DK, Donson AM, Patel PR, et al.
High expression of BMP pathway genes distinguishes a subset of atypical teratoid/rhabdoid tumors associated with shorter survival.
Neuro Oncol. 2011; 13(12):1296-307 [PubMed] Article available free on PMC after 01/04/2017 Related Publications
Molecular profiling of tumors has proven to be a valuable tool for identification of prognostic and diagnostic subgroups in medulloblastomas, glioblastomas, and other cancers. However, the molecular landscape of atypical teratoid/rhabdoid tumors (AT/RTs) remains largely unexplored. To address this issue, we used microarrays to measure the gene expression profiles of 18 AT/RTs and performed unsupervised hierarchical clustering to determine molecularly similar subgroups. Four major subgroups (clusters) were identified. These did not conform to sex, tumor location, or presence of monosomy 22. Clusters showed distinct gene signatures and differences in enriched biological processes, including elevated expression of some genes associated with choroid plexus lineage in cluster 4. In addition, survival differed significantly by cluster, with shortest survival (mean, 4.7 months) in both clusters 3 and 4, compared with clusters 1 and 2 (mean, 28.1 months). Analysis showed that multiple bone morphogenetic protein (BMP) pathway genes were upregulated in the short survival clusters, with BMP4 showing the most significant upregulation (270-fold). Thus, high expression of BMP pathway genes was negatively associated with survival in this dataset. Our study indicates that molecular subgroups exist in AT/RTs and that molecular profiling of these comparatively rare tumors may be of diagnostic, prognostic, and therapeutic value.

Birks DK, Barton VN, Donson AM, et al.
Survey of MicroRNA expression in pediatric brain tumors.
Pediatr Blood Cancer. 2011; 56(2):211-6 [PubMed] Related Publications
BACKGROUND: A better understanding of pediatric brain tumor biology is needed to assist in the development of less toxic therapies and to provide better markers for disease stratification. MicroRNAs (miRNA) may play a significant role in brain tumor biology. The present study provides an initial survey of miRNA expression in pediatric central nervous system (CNS) malignancies including atypical teratoid/rhabdoid tumor, ependymoma, glioblastoma, medulloblastoma, and pilocytic astrocytoma.
PROCEDURE: MicroRNA expression in pediatric brain tumors and normal tissue controls was examined by microarray. Three aberrantly expressed miRNAs were further studied in a larger cohort by quantitative real-time PCR (qRT-PCR).
RESULTS: MicroRNA-129, miR-142-5p, and miR-25 were differentially expressed in every pediatric brain tumor type compared to normal tissue controls as measured by microarray. When further examined by qRT-PCR, these miRNAs demonstrated differential expression that significantly correlated with the microarray findings. Distinctive miRNA expression profiles were also observed in the different pediatric brain tumor types.
CONCLUSIONS: MicroRNAs are differentially expressed between pediatric CNS neoplasms and normal tissue suggesting that they may play a significant role in oncogenesis. A greater understanding of aberrant miRNA expression in pediatric brain tumors may aid in the development of novel therapies. The characterization of tumor-specific miRNA signatures may aid in the discovery of biomarkers with diagnostic or prognostic utility.

Madden JR, Addo-Yobo SO, Donson AM, et al.
Radiation-induced glioblastoma multiforme in children treated for medulloblastoma with characteristics of both medulloblastoma and glioblastoma multiforme.
J Pediatr Hematol Oncol. 2010; 32(7):e272-8 [PubMed] Related Publications
Outcomes for average-risk medulloblastoma are excellent with 5-year event-free survival and overall survival>80%. Treatment failures include radiation-induced glioblastomas (RIG), which are often diagnosed solely on imaging. Recent studies suggest that RIGs differ from spontaneous glioblastoma multiforme (GBM), based on microarray gene-expression profiling. Retrospective review of children with average-risk medulloblastoma treated from 1996 to 2003 included 16 patients with 5 treatment failures. One died of disease progression, 1 died as a result of radiation necrosis, and 3 children died of pathology-confirmed GBM. Of these 3 GBMs, one was studied with electron microscopy, cytogenetics, and gene-expression microarray analysis. This tumor had focal medulloblastoma and similarity by gene-expression microarray with other RIGs. With both components in the recurrent tumor, we suggest it was in the process of transitioning from medulloblastoma to RIG, that is, "catching the tumor in the act." Some radiation-induced nervous system tumors may develop as a direct result of severe oncologic changes within the original tumor cells, with the tumor evolving into a different phenotypic tumor type. We recommend biopsy for tissue confirmation and genetic expression profile to shed light on the etiology of radiation-induced neoplasms.

Barton VN, Foreman NK, Donson AM, et al.
Aurora kinase A as a rational target for therapy in glioblastoma.
J Neurosurg Pediatr. 2010; 6(1):98-105 [PubMed] Related Publications
OBJECT: Despite advances in the knowledge of tumor biology, the outcome of glioblastoma tumors remains poor. The design of many molecularly targeted therapies in glioblastoma has focused on inhibiting molecular abnormalities present in tumor cells compared with normal tissue rather than patient outcome-associated factors. As an alternative approach, the present study identified genes associated with shorter survival as potential therapeutic targets. It was hypothesized that inhibition of a molecular target associated with poor outcome would impact glioblastoma cell proliferation.
METHODS: The present study correlated patient survival data with tumor gene expression profiling and gene ontology analysis. Genes associated with shorter survival were identified and one of these was selected for therapeutic targeting in an in vitro system. Glioblastoma cell growth suppression was measured by H(3)-thymidine uptake, colony formation, and flow cytometry.
RESULTS: The gene expression microarray and ontology analysis revealed that genes involved in mitotic processes, including AURKA, were associated with poor prognosis in glioblastoma. Inhibition of AURKA suppressed glioblastoma cell growth. Moreover, inhibition of AURKA was synergistic with radiation in glioblastoma cells at high radiation doses.
CONCLUSIONS: Relative expression of AURKA may be of prognostic value and warrants further investigation with larger, prospective studies. Pharmacological inhibition of AURKA is a potentially promising therapy for glioblastoma.

Keating AK, Kim GK, Jones AE, et al.
Inhibition of Mer and Axl receptor tyrosine kinases in astrocytoma cells leads to increased apoptosis and improved chemosensitivity.
Mol Cancer Ther. 2010; 9(5):1298-307 [PubMed] Article available free on PMC after 01/04/2017 Related Publications
Astrocytomas account for the majority of malignant brain tumors diagnosed in both adult and pediatric patients. The therapies available to treat these neoplasms are limited, and the prognosis associated with high-grade lesions is extremely poor. Mer (MerTK) and Axl receptor tyrosine kinases (RTK) are expressed at abnormally high levels in a variety of malignancies, and these receptors are known to activate strong antiapoptotic signaling pathways that promote oncogenesis. In this study, we found that Mer and Axl mRNA transcript and protein expression were elevated in astrocytic patient samples and cell lines. shRNA-mediated knockdown of Mer and Axl RTK expression led to an increase in apoptosis in astrocytoma cells. Apoptotic signaling pathways including Akt and extracellular signal-regulated kinase 1/2, which have been shown to be activated in resistant astrocytomas, were downregulated with Mer and Axl inhibition whereas poly(ADP-ribose) polymerase cleavage was increased. Furthermore, Mer and Axl shRNA knockdown led to a profound decrease of astrocytoma cell proliferation in soft agar and a significant increase in chemosensitivity in response to temozolomide, carboplatin, and vincristine treatment. Our results suggest Mer and Axl RTK inhibition as a novel method to improve apoptotic response and chemosensitivity in astrocytoma and provide support for these oncogenes as attractive biological targets for astrocytoma drug development.

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