Search

The significant sex differences that exist in cancer mechanisms, incidence, and survival, have yet to impact clinical practice. We hypothesized that one barrier to translation is that sex differences in cancer phenotypes resemble sex differences in height: highly overlapping, but distinct, male and female population distributions that vary continuously between female- and male-biased extremes. A consequence of this variance is that sex-specific treatments are rendered unrealistic, and our translational goal should be adaptation of treatment to the unique mix of sex-biased mechanisms that are present in each patient. To develop a tool that could advance this goal, we applied a Bayesian Nearest Neighbor (BNN) analysis to 8370 cancer transcriptomes from 26 different adult and 4 different pediatric cancer types to establish patient-specific Transcriptomic Sex Indices (TSI). TSI precisely partitions an individual patient’s whole transcriptome into female- and male-biased components such that cancer type, patient sex, and transcriptomics, provide a novel and patient-specific mechanistic identifier that can be used for sex-adapted, precision cancer treatment planning.

G-protein–coupled receptor kinases (GRK) regulate the function of G-protein–coupled receptors (GPCR). Previously, we found that GPCR (CXCR4)-mediated astrocytoma growth was dependent upon abnormally sustained CXCR4 signaling and was correlated with decreased GRK-mediated receptor phosphorylation. As CXCR4 has also been implicated in the stimulation of high-grade glioma growth, we sought to determine whether dysregulation of GRK expression and/or function might also be present in high-grade gliomas. In an analysis of data from The Cancer Genome Atlas, we found that GRK3 expression is frequently decreased in glioblastoma (GBM) of the classical subtype, which possesses signature amplification or mutational activation of the epidermal growth factor (EGF) receptor. We tested the correlation between GRK3 expression and GBM subtypes, as well as the relationship between the activation of the EGF and other growth factor receptor pathways and GRK expression. In analyses of primary GBM tissue and RNA specimens, we found that GRK3 expression is correlated with established criteria for GBM subtyping including expression of EGF receptor, platelet-derived growth factor receptor (PDGFR)α, NF1, PTEN, CDKN2A, and neurofilament. We also found that established drivers of gliomagenesis, the EGF, PDGF, and TGF-β pathways, all regulate GRK expression. Coculture experiments, designed to mimic critical interactions between tumor and brain microvascular endothelial cells, showed that specifically increasing GRK3 expression reduced the trophic effect of endothelial cells on tumor cells. Together, these experiments show that GRK3 is a negative regulator of cell growth whose expression is preferentially reduced in GBM of the classical subtype as a consequence of activity in primary gliomagenic pathways. Mol Cancer Res; 10(1); 156–66. ©2011 AACR.

PDF file - 48KB

PDF file - 1979KB

PDF file - 7422KB

PDF file - 63KB

PDF file - 116KB

PDF file - 66KB

PDF file - 66KB

PDF file - 4786KB

Purpose: As favorable outcomes from malignant brain tumors remain limited by poor survival and treatment-related toxicity, novel approaches to cure are essential. Previously, we identified the cyclic AMP phosphodiesterase-4 (PDE4) inhibitor Rolipram as a potent antitumor agent. Here, we investigate the role of PDE4 in brain tumors and examine the utility of PDE4 as a therapeutic target.Experimental Design: Immunohistochemistry was used to evaluate the expression pattern of a subfamily of PDE4, PDE4A, in multiple brain tumor types. To evaluate the effect of PDE4A on growth, a brain-specific isoform, PDE4A1 was overexpressed in xenografts of Daoy medulloblastoma and U87 glioblastoma cells. To determine therapeutic potential of PDE4 inhibition, Rolipram, temozolomide, and radiation were tested alone and in combination on mice bearing intracranial U87 xenografts.Results: We found that PDE4A is expressed in medulloblastoma, glioblastoma, oligodendroglioma, ependymoma, and meningioma. Moreover, when PDE4A1 was overexpressed in Daoy medulloblastoma and U87 glioblastoma cells, in vivo doubling times were significantly shorter for PDE4A1-overexpressing xenografts compared with controls. In long-term survival and bioluminescence studies, Rolipram in combination with first-line therapy for malignant gliomas (temozolomide and conformal radiation therapy) enhanced the survival of mice bearing intracranial xenografts of U87 glioblastoma cells. Bioluminescence imaging indicated that whereas temozolomide and radiation therapy arrested intracranial tumor growth, the addition of Rolipram to this regimen resulted in tumor regression.Conclusions: This study shows that PDE4 is widely expressed in brain tumors and promotes their growth and that inhibition with Rolipram overcomes tumor resistance and mediates tumor regression.

Supplementary Figures S1-S3 from Targeted Inhibition of Cyclic AMP Phosphodiesterase-4 Promotes Brain Tumor Regression

Supplementary Figure 2 from Spatiotemporal Differences in CXCL12 Expression and Cyclic AMP Underlie the Unique Pattern of Optic Glioma Growth in Neurofibromatosis Type 1

Supplementary Figure 1 from Cyclic AMP Suppression Is Sufficient to Induce Gliomagenesis in a Mouse Model of Neurofibromatosis-1

Supplementary Figure 2 from Blocking CXCR4-Mediated Cyclic AMP Suppression Inhibits Brain Tumor Growth In vivo

The chemokine CXCL12 and its cognate receptor CXCR4 regulate malignant brain tumor growth and are potential chemotherapeutic targets. However, the molecular basis for CXCL12-induced tumor growth remains unclear, and the optimal approach to inhibiting CXCR4 function in cancer is unknown. To develop such a therapeutic approach, we investigated the signaling pathways critical for CXCL12 function in normal and malignant cells. We discovered that CXCL12-dependent tumor growth is dependent upon sustained inhibition of cyclic AMP (cAMP) production, and that the antitumor activity of the specific CXCR4 antagonist AMD 3465 is associated with blocking cAMP suppression. Consistent with these findings, we show that pharmacologic elevation of cAMP with the phosphodiesterase inhibitor Rolipram suppresses tumor cell growth in vitro and, upon oral administration, inhibits intracranial growth in xenograft models of malignant brain tumors with comparable efficacy to AMD 3465. These data indicate that the clinical evaluation of phosphodiesterase inhibitors in the treatment of patients with brain tumors is warranted. [Cancer Res 2007;67(2):651–8]

The chemokine receptor CXCR4 is expressed in many cancers where it may regulate tumor cell growth and migration. The role of CXCR4 in cancer will depend on it being in an activated, signaling state. To better define the significance of CXCR4 expression in cancer, we developed an antibody that can distinguish CXCR4 phosphorylated on serine 339, a residue previously identified as a site for ligand-induced phosphorylation. With this antibody, we investigated the mechanisms of CXCR4 phosphorylation and evaluated the phosphorylation status of CXCR4 in human astrocytomas. In vitro, phosphorylation of serine 339 occurred in response to CXCL12 or epidermal growth factor (EGF) treatment and was increased by protein kinase C activation. In all grades of astrocytomas, CXCR4 was expressed in tumor cells and some endothelial cells, whereas CXCL12 was present in endothelial cells and infiltrating microglia. We found that CXCR4 phosphorylated on serine 339 was present in tumor cells and vascular endothelial cells in all grades of astrocytoma. These data indicate that CXCR4 is expressed and activated in astrocytomas and that phosphorylation of CXCR4 can occur through ligand activation or transactivation via the EGF receptor. These studies extend the potential roles of CXCR4 in cancer to include functions associated with benign (grade 1) tumors. The ability to distinguish phosphorylated CXCR4 will be invaluable for the continued analysis of the role of CXCR4 in cancer and the development of CXCR4 antagonist therapy for patients suffering with primary tumors of the brain and other sites. (Cancer Res 2005; 65(24): 11392-9)

Supplementary Figure 1 from Widespread CXCR4 Activation in Astrocytomas Revealed by Phospho-CXCR4-Specific Antibodies

Supplemental Table 3. Primer sequences.

Supplementary Figure 3 from Blocking CXCR4-Mediated Cyclic AMP Suppression Inhibits Brain Tumor Growth In vivo

Supplementary Table 1 from Blocking CXCR4-Mediated Cyclic AMP Suppression Inhibits Brain Tumor Growth In vivo

Supplementary Figure 1 from Spatiotemporal Differences in CXCL12 Expression and Cyclic AMP Underlie the Unique Pattern of Optic Glioma Growth in Neurofibromatosis Type 1

PDF file - 2MB

Supplementary Figure 4 from Cyclic AMP Suppression Is Sufficient to Induce Gliomagenesis in a Mouse Model of Neurofibromatosis-1

Supplementary Figure 1 from Blocking CXCR4-Mediated Cyclic AMP Suppression Inhibits Brain Tumor Growth In vivo

Current models of oncogenesis incorporate the contributions of chronic inflammation and aging to the patterns of tumor formation. These oncogenic pathways, involving leukocytes and fibroblasts, are not readily applicable to brain tumors (glioma), and other mechanisms must account for microenvironmental influences on central nervous system tumorigenesis. Previous studies from our laboratories have used neurofibromatosis-1 (NF1) genetically engineered mouse (GEM) models to understand the spatial restriction of glioma formation to the optic pathway of young children. Based on our initial findings, we hypothesize that brain region–specific differences in cAMP levels account for the pattern of NF1 gliomagenesis. To provide evidence that low levels of cAMP promote glioma formation in NF1, we generated foci of decreased cAMP in brain regions where gliomas rarely form in children with NF1. Focal cAMP reduction was achieved by forced expression of phosphodiesterase 4A1 (PDE4A1) in the cortex of Nf1 GEM strains. Ectopic PDE4A1 expression produced hypercellular lesions with features of human NF1-associated glioma. Conversely, pharmacologic elevation of cAMP with the PDE4 inhibitor rolipram dramatically inhibited optic glioma growth and tumor size in Nf1 GEM in vivo. Together, these results indicate that low levels of cAMP in a susceptible Nf1 mouse strain are sufficient to promote gliomagenesis, and justify the implementation of cAMP-based stroma-targeted therapies for glioma. Cancer Res; 70(14); 5717–27. ©2010 AACR.

Supplemental Table 1: Specimen Characteristics.

Supplementary Legends 1-2 from Spatiotemporal Differences in CXCL12 Expression and Cyclic AMP Underlie the Unique Pattern of Optic Glioma Growth in Neurofibromatosis Type 1

OBJECTIVE Pilocytic astrocytomas (PAs) have a generally favorable prognosis; however, progression or recurrence after resection is possible. The prognostic value of histopathological qualifiers (defined below) or BRAF alterations is not well understood. The aim of this study was to identify the prognostic value of genetic and histopathological features of pediatric PAs. METHODS Patients treated for a WHO grade I PA at a single institution were analyzed for histopathological and genetic features and outcomes. “Histopathological qualifier” refers to designations such as "WHO grade I PA with increased proliferative index." BRAF alterations include gene fusions and point mutations. Patients with neurofibromatosis type 1 were excluded. RESULTS A total of 222 patients were analyzed (51% female, mean age 9.6 years). Tumors were located in the cerebellum/fourth ventricle (51%), optic pathway/hypothalamus (15%), brainstem (12%), and cerebral cortex (11%). BRAF alterations were screened for in 77 patients and identified in 56 (73%). Histopathological qualifiers were present in 27 patients (14%). Resection was performed in 197 patients (89%), 41 (21%) of whom displayed tumor progression or recurrence after resection. Tumor progression or recurrence was not associated with histopathologic qualifiers (p = 0.36) or BRAF alterations (p = 0.77). Ki-67 proliferative indices were not predictive of progression or recurrence (p = 0.94). BRAF alterations, specifically KIAA1549 fusions, were associated with cerebellar/fourth ventricular tumor location (p < 0.0001) and younger patient age (p = 0.03). Patients in whom gross-total resection was achieved had lower rates of progression and recurrence (p < 0.0001). CONCLUSIONS Histopathological features/qualifiers and BRAF alterations were not associated with tumor recurrence/progression in pediatric PAs. The extent of resection was the only factor analyzed that predicted outcome.

Background Gliomas are the most common primary brain tumor in adults. Current treatments involve surgery, radiation, and temozolomide (TMZ) chemotherapy; however, prognosis remains poor and new approaches are required. Circadian medicine aims to maximize treatment efficacy and/or minimize toxicity by timed delivery of medications in accordance with the daily rhythms of the patient. We published a retrospective study showing greater anti-tumor efficacy for the morning, relative to the evening, administration of TMZ in patients with glioblastoma. We conducted this prospective randomized trial to determine the feasibility, and potential clinical impact, of TMZ chronotherapy in patients with gliomas (NCT02781792). Methods Adult patients with gliomas (WHO grade II-IV) were enrolled prior to initiation of monthly TMZ therapy and were randomized to receive TMZ either in the morning (AM) before 10 am or in the evening (PM) after 8 pm. Pill diaries were recorded to measure compliance and FACT-Br quality of life (QoL) surveys were completed throughout treatment. Study compliance, adverse events (AE), and overall survival were compared between the two arms. Results A total of 35 evaluable patients, including 21 with GBM, were analyzed (18 AM patients and 17 PM patients). Compliance data demonstrated the feasibility of timed TMZ dosing. There were no significant differences in AEs, QoL, or survival between the arms. Conclusions Chronotherapy with TMZ is feasible. A larger study is needed to validate the effect of chronotherapy on clinical efficacy.

Researchers are exploring sex differences in experimental models of both development and disease—but are we doing enough? In this collection of Voices, we celebrate researchers who are asking this question and starting to offer mechanistic clues on sexually dimorphic differences seen in interorgan communication, metabolic disease, neurological disorders, and more.

Background/purpose Glioblastoma (GBM) is the most common primary malignant brain tumor. Sex has been shown to be an important prognostic factor for GBM. The purpose of this study was to develop and independently validate sex-specific nomograms for estimation of individualized GBM survival probabilities using data from 2 independent NRG Oncology clinical trials. Methods This analysis included information on 752 (NRG/RTOG 0525) and 599 (NRG/RTOG 0825) patients with newly diagnosed GBM. The Cox proportional hazard models by sex were developed using NRG/RTOG 0525 and significant variables were identified using a backward selection procedure. The final selected models by sex were then independently validated using NRG/RTOG 0825. Results Final nomograms were built by sex. Age at diagnosis, KPS, MGMT promoter methylation and location of tumor were common significant predictors of survival for both sexes. For both sexes, tumors in the frontal lobes had significantly better survival than tumors of multiple sites. Extent of resection, and use of corticosteroids were significant predictors of survival for males. Conclusions A sex specific nomogram that assesses individualized survival probabilities (6-, 12- and 24-months) for patients with GBM could be more useful than estimation of overall survival as there are factors that differ between males and females. A user friendly online application can be found here—https://npatilshinyappcalculator.shinyapps.io/SexDifferencesInGBM/.

Glioblastoma (GBM) is the most common primary malignant brain tumor in adults. Prior studies examining the mutational landscape of GBM revealed recurrent alterations in genes that regulate the same growth control pathways. To this regard, ~ 40% of GBM harbor EGFR alterations, whereas BRAF variants are rare. Existing data suggests that gain-of-function mutations in these genes are mutually exclusive. This study was designed to explore the clinical, pathological, and molecular differences between EGFR- and BRAF-mutated GBM. We reviewed retrospective clinical data from 89 GBM patients referred for molecular testing between November 2012 and December 2015. Differences in tumor mutational profile, location, histology, and survival outcomes were compared in patients with EGFR- versus BRAF-mutated tumors, and microarray data from The Cancer Genome Atlas was used to assess differential gene expression between the groups. Individuals with BRAF-mutant tumors were typically younger and survived longer relative to those with EGFR-mutant tumors, even in the absence of targeted treatments. BRAF-mutant tumors lacked distinct histomorphology but exhibited unique localization in the brain, typically arising adjacent to the lateral ventricles. Compared to EGFR- and IDH1-mutant tumors, BRAF-mutant tumors showed increased expression of genes related to a trophoblast-like phenotype, specifically HLA-G and pregnancy specific glycoproteins, that have been implicated in invasion and immune evasion. Taken together, these observations suggest a distinct clinical presentation, brain location, and gene expression profile for BRAF-mutant tumors. Pending further study, this may prove useful in the stratification and management of GBM.