Faculty Bibliography

Mutant isocitrate dehydrogenase 1 (IDH1) is common in gliomas, and produces D-2-hydroxyglutarate (D-2-HG). The full effects of IDH1 mutations on glioma biology and tumor microenvironment are unknown. We analyzed a discovery cohort of 169 World Health Organization (WHO) grade II-IV gliomas, followed by a validation cohort of 148 cases, for IDH1 mutations, intratumoral microthrombi, and venous thromboemboli (VTE). 430 gliomas from The Cancer Genome Atlas were analyzed for mRNAs associated with coagulation, and 95 gliomas in a tissue microarray were assessed for tissue factor (TF) protein. In vitro and in vivo assays evaluated platelet aggregation and clotting time in the presence of mutant IDH1 or D-2-HG. VTE occurred in 26-30 % of patients with wild-type IDH1 gliomas, but not in patients with mutant IDH1 gliomas (0 %). IDH1 mutation status was the most powerful predictive marker for VTE, independent of variables such as GBM diagnosis and prolonged hospital stay. Microthrombi were far less common within mutant IDH1 gliomas regardless of WHO grade (85-90 % in wild-type versus 2-6 % in mutant), and were an independent predictor of IDH1 wild-type status. Among all 35 coagulation-associated genes, F3 mRNA, encoding TF, showed the strongest inverse relationship with IDH1 mutations. Mutant IDH1 gliomas had F3 gene promoter hypermethylation, with lower TF protein expression. D-2-HG rapidly inhibited platelet aggregation and blood clotting via a novel calcium-dependent, methylation-independent mechanism. Mutant IDH1 glioma engraftment in mice significantly prolonged bleeding time. Our data suggest that mutant IDH1 has potent antithrombotic activity within gliomas and throughout the peripheral circulation. These findings have implications for the pathologic evaluation of gliomas, the effect of altered isocitrate metabolism on tumor microenvironment, and risk assessment of glioma patients for VTE.

High-grade glioma (HGG), a deadly primary brain malignancy, manifests radioresistance mediated by cell-intrinsic and microenvironmental mechanisms. High levels of the cytokine transforming growth factor-beta (TGF-beta) in HGG promote radioresistance by enforcing an effective DNA damage response and supporting glioma stem cell self-renewal. Our analysis of HGG TCGA data and immunohistochemical staining of phosphorylated Smad2, which is the main transducer of canonical TGF-beta signaling, indicated variable levels of TGF-beta pathway activation across HGG tumors. These data suggest that evaluating the putative benefit of inhibiting TGF-beta during radiotherapy requires personalized screening. Thus, we used explant cultures of seven HGG specimens as a rapid, patient-specific ex vivo platform to test the hypothesis that LY364947, a small molecule inhibitor of the TGF-beta type I receptor, acts as a radiosensitizer in HGG. Immunofluorescence detection and image analysis of gamma-H2AX foci, a marker of cellular recognition of radiation-induced DNA damage, and Sox2, a stem cell marker that increases post-radiation, indicated that LY364947 blocked these radiation responses in five of seven specimens. Collectively, our findings suggest that TGF-beta signaling increases radioresistance in most, but not all, HGGs. We propose that short-term culture of HGG explants provides a flexible and rapid platform for screening context-dependent efficacy of radiosensitizing agents in patient-specific fashion. This time- and cost-effective approach could be used to personalize treatment plans in HGG patients.

Solid papillary carcinoma with reverse polarity (SPCRP) is a rare breast cancer subtype with an obscure etiology. In this study, we sought to describe its unique histopathologic features and to identify the genetic alterations that underpin SPCRP using massively parallel whole-exome and targeted sequencing. The morphologic and immunohistochemical features of SPCRP support the invasive nature of this subtype. Ten of 13 (77%) SPCRPs harbored hotspot mutations at R172 of the isocitrate dehydrogenase IDH2, of which 8 of 10 displayed concurrent pathogenic mutations affecting PIK3CA or PIK3R1 One of the IDH2 wild-type SPCRPs harbored a TET2 Q548* truncating mutation coupled with a PIK3CA H1047R hotspot mutation. Functional studies demonstrated that IDH2 and PIK3CA hotspot mutations are likely drivers of SPCRP, resulting in its reversed nuclear polarization phenotype. Our results offer a molecular definition of SPCRP as a distinct breast cancer subtype. Concurrent IDH2 and PIK3CA mutations may help diagnose SPCRP and possibly direct effective treatment. Cancer Res; 76(24); 1-12. (c)2016 AACR.

OBJECTIVE: Pediatric optic pathway gliomas (OPGs) are often considered benign, but can have detrimental effects on the quality of life, impair vision and are a potentially lethal disease. The aim of this study is to report the characteristics and outcomes of surgically treated OPGs and to identify candidates for different treatment strategies. MATERIAL-METHODS: Retrospective chart review of consecutive pediatric patients with surgically treated OPGs by a single surgeon at our institution from 1985-2015. Three treatment pathways were defined: surgery without planned adjuvant therapy (1), surgery with planned adjuvant therapy (2) and patients with prior treatment (3). RESULTS:88 patients - 49 male and 39 female - were included in analysis. 8 patients had NF1. Pathology revealed pilocytic astrocytoma (85.2%), pilomyxoid astrocytoma (8%), and pilocytic/pilomyxoid astrocytoma (5.7%). Radiologic location of the tumor was: hypothalamic (87%), and involvement of only chiasmand/or tract in (13%).Median age at diagnosiswas 4 years, median age at surgery was 6 years, and median time from diagnosis to surgery was 1 year. At the time of the study: Pathway 1: 37 patients; median PFS 84 +/- 33.4; median OS of 118 months (range: 24 - 337 months); OS rate 68%. Pathway 2: 9 patients; median PFS 45 +/- 10.9 months; median OS of 127 months (range: 23 - 368 months); OS rate 67%. Pathway 3: 42 patients; median PFS 74 +/- 13.3 months; median OS of 69 months (range: 7 - 356) months; OS rate 76%.. CONCLUSIONS: The role of surgery in the treatment of pediatric OPGs depends on patient characteristics and tumor biology. With the adequate therapeutic strategy, long-term PFS and OS can be achieved

Glioblastoma (GBM) is a deadly primary brain malignancy with extensive intratumoral hypoxia. Hypoxic regions of GBM contain stem-like cells and are associated with tumor growth and angiogenesis. The molecular mechanisms that regulate tumor growth in hypoxic conditions are incompletely understood. Here, we use primary human tumor biospecimens and cultures to identify GPR133 (ADGRD1), an orphan member of the adhesion family of G-protein-coupled receptors, as a critical regulator of the response to hypoxia and tumor growth in GBM. GPR133 is selectively expressed in CD133+ GBM stem cells (GSCs) and within the hypoxic areas of PPN in human biospecimens. GPR133 mRNA is transcriptionally upregulated by hypoxia in hypoxia-inducible factor 1alpha (Hif1alpha)-dependent manner. Genetic inhibition of GPR133 with short hairpin RNA reduces the prevalence of CD133+ GSCs, tumor cell proliferation and tumorsphere formation in vitro. Forskolin rescues the GPR133 knockdown phenotype, suggesting that GPR133 signaling is mediated by cAMP. Implantation of GBM cells with short hairpin RNA-mediated knockdown of GPR133 in the mouse brain markedly reduces tumor xenograft formation and increases host survival. Analysis of the TCGA data shows that GPR133 expression levels are inversely correlated with patient survival. These findings indicate that GPR133 is an important mediator of the hypoxic response in GBM and has significant protumorigenic functions. We propose that GPR133 represents a novel molecular target in GBM and possibly other malignancies where hypoxia is fundamental to pathogenesis.

Introduction: Pediatric optic pathway gliomas (OPGs) are often considered benign, but can have detrimental effects on the quality of life, impair vision and are a potentially lethal disease. The aim of this study is to report the characteristics and outcomes of surgically treated pediatric OPGs and to identify candidates for different treatment strategies. Methods: Retrospective chart review of consecutive pediatric patients with surgically treated OPGs by a single surgeon at our institution from 1985-2015. Three treatment pathways were defined: (1) surgery without planned adjuvant therapy; (2) surgery with planned adjuvant therapy; and, (3) patients with prior treatment.Results: 100 patients-55 male and 45 female-were included in analysis. 8 patients had NF1. Pathology revealed pilocytic astrocytoma (45%), pilomyxoid astrocytoma (9%), ganglioglioma (3%), and unknown (35%). Radiologic location of the tumor was: hypothalamic 86%, involvement of only chiasm and/or tract in 12%. Median age at diagnosis was 4 years, median age at surgery was 6 years, and median time from diagnosis to surgery was 1 year. Pathway 1: 39 patients; median PFS 73+17 months; OS rate 74%; median follow-up 117 months. Pathway 2: 10 patients; median PFS 29+15 months; OS rate 70%; median follow-up 59 months. Pathway 3: 51 patients; median PFS 33+8 months; OS rate 80%; median follow-up was 73 months. Conclusion: The role of surgery in the treatment of pediatric OPGs depends on patient characteristics and tumor biology. With the adequate therapeutic strategy, long-term PFS and OS can be achieved