Allison Hanaford

DiSCoVERing Innovative Therapies for Rare Tumors: Combining Genetically Accurate Disease Models with In Silico Analysis to Identify Novel Therapeutic Targets.

Purpose: We used human stem and progenitor cells to develop a genetically accurate novel model of MYC-driven Group 3 medulloblastoma. We also developed a new informatics method, Disease-model Signature versus Compound-Variety Enriched Response (“DiSCoVER”), to identify novel therapeutics that target this specific disease subtype. Experimental Design: Human neural stem and progenitor cells derived from the cerebellar anlage were transduced with oncogenic elements associated with aggressive medulloblastoma. An in silico analysis method for screening drug sensitivity databases (DiSCoVER) was used in multiple drug sensitivity datasets. We validated the top hits from this analysis in vitro and in vivo. Results: Human neural stem and progenitor cells transformed with c-MYC, dominant-negative p53, constitutively active AKT and hTERT formed tumors in mice that recapitulated Group 3 medulloblastoma in terms of pathology and expression profile. DiSCoVER analysis predicted that aggressive MYC-driven Group 3 medulloblastoma would be sensitive to cyclin-dependent kinase (CDK) inhibitors. The CDK 4/6 inhibitor palbociclib decreased proliferation, increased apoptosis, and significantly extended the survival of mice with orthotopic medulloblastoma xenografts. Conclusions: We present a new method to generate genetically accurate models of rare tumors, and a companion computational methodology to find therapeutic interventions that target them. We validated our human neural stem cell model of MYC-driven Group 3 medulloblastoma and showed that CDK 4/6 inhibitors are active against this subgroup. Our results suggest that palbociclib is a potential effective treatment for poor prognosis MYC-driven Group 3 medulloblastoma tumors in carefully selected patients. Clin Cancer Res; 22(15); 3903–14. ©2016 AACR.

Clipping the Wings of Glioblastoma: Modulation of WNT as a Novel Therapeutic Strategy

Glioblastoma (GBM) is the most malignant brain tumor and has a dismal prognosis. Aberrant WNT signaling is known to promote glioma cell growth and dissemination and resistance to conventional radio- and chemotherapy. Moreover, a population of cancer stem-like cells that promote glioma growth and recurrence are strongly dependent on WNT signaling. Here, we discuss the role and mechanisms of aberrant canonical and noncanonical WNT signaling in GBM. We present current clinical approaches aimed at modulating WNT activity and evaluate their clinical perspective as a novel treatment option for GBM.

Targeting Notch signaling as a novel therapy for retinoblastoma

Retinoblastoma is the most common intraocular malignancy of childhood. Notch plays a key role in retinal cells from which retinoblastomas arise, and we therefore studied the role of Notch signaling in promoting retinoblastoma proliferation. Moderate or strong nuclear expression of Hes1 was found in 10 of 11 human retinoblastoma samples analyzed immunohistochemically, supporting a role for Notch in retinoblastoma growth. Notch pathway components were present in WERI Rb1 and Y79 retinoblastoma lines, with Jag2 and DLL4 more highly expressed than other ligands, and Notch1 and Notch2 more abundant than Notch3. The cleaved/active form of Notch1 was detectable in both lines. Inhibition of the pathway, achieved using a γ-secretase inhibitor (GSI) or by downregulating Jag2, DLL4 or CBF1 using short hairpin RNA, potently reduced growth, proliferation and clonogenicity in both lines. Upregulation of CXCR4 and CXCR7 and downregulation of PI3KC2β were identified by microarray upon Jag2 suppression. The functional importance of PI3KC2β was confirmed using shRNA. Synergy was found by combining GSI with Melphalan at their IC50. These findings indicate that Notch pathway is active in WERI Rb1 and Y79, and in most human retinoblastoma samples, and suggest that Notch antagonists may represent a new approach to more effectively treat retinoblastoma.

Abstract 3549: C-MYC sensitizes GBM with primitive features to glutamine metabolism disruption

Glioblastoma (GBM) is among the most lethal of known human cancers, with a median survival of less than 15 months. The highly infiltrative nature and genetic heterogeneity of GBM renders treatment difficult. Therefore, better and more targeted therapies are needed for patients with GBM. There is a new WHO subset of GBM that contains primitive neuronal components (GBM-PNC). These tumors can arise from a histologically classic GBM, and often the GBM-PNC portions of the tumor contain C-MYC or N-MYC amplifications. High MYC expression is known to alter cellular metabolism, increasing reliance on glutamine, which may create opportunities for therapeutic intervention. We hypothesized that depriving GBM-PNC cells of glutamine using metabolic inhibitors would suppress growth and tumorigenicity. To create genetically appropriate GBM-PNC models, we derived cortex (CTX) human neural stem cells and transformed them through lentiviral expression of mutant p53, constitutively-active AKT and hTERT. Transformed neurospheres were then lentivirally transduced with either C-MYC or BMI1. These models formed aggressive tumors in mice and recapitulated the histological features of GBM with expression of NESTIN, GFAP, and MAP2. When treated with the glutamine metabolic inhibitors DON or Acivicin, transformed neurospheres that expressed C-MYC had decreased cellular proliferation (BrdU incorporation, P Citation Format: Brad Andrew Poore, Isabella Taylor, Jeffrey Rubens, Allison Hanaford, Micah Maxwell, Charles Eberhart, Eric Raabe. C-MYC sensitizes GBM with primitive features to glutamine metabolism disruption [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 3549. doi:10.1158/1538-7445.AM2017-3549

Abstract 5051: MYC-driven models of primitive neuroectodermal tumor are sensitive to inhibitors of glutamine metabolism.

Brain tumors are a diverse group of cancers in which alterations in growth regulation pathways drive tumorigenicity. Histologically similar tumors may have significant differences in underlying molecular pathways and this in turn may have significant implications for the development of targeted treatment. The MYC family of proteins promotes proliferation and an aggressive phenotype in diverse cancers. Primitive Neuroectodermal Tumors (PNETs) are high grade tumors that can arise throughout the neuro-axis. One subset of PNETs is MYC amplified, and some PNETs are known to express LIN28A, a key regulator of MYC. MYC expression in tumors leads to increased reliance on glutamine metabolism (i.e. the Warburg effect). We hypothesized that MYC-driven PNET tumors would up regulate glutamine metabolism and that glutaminase inhibitors would selectively target MYC-driven tumors. We tested this hypothesis using the MYC-positive PNET cell line PFSK as well as MYC-transformed human neural stem cells. The glutamine methabolic inhibitors DON (6-Diazo-5-oxo-L-norleucine) and acivicin were used to disrupt glutamine metabolism in these cells. Using Tetrazolium dye reduction (MTT assay) and Bromodeoxyuridine assays (BrdU) as indicators for cell growth and replication, we found that PFSK growth is inhibited by acivicin at 10 micromolar concentration (MTT activity reduced by 88%, p Citation Format: Sama F. Ahsan, Allison Hanaford, Melanie Weingart, Isabella Taylor, Charles Eberhart, Eric Raabe. MYC-driven models of primitive neuroectodermal tumor are sensitive to inhibitors of glutamine metabolism. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 5051. doi:10.1158/1538-7445.AM2013-5051