Article

Epigenetic pathways and glioblastoma treatment.

University of Miami Miller School of Medicine
Epigenetics: official journal of the DNA Methylation Society (Impact Factor: 5.11). 06/2013; 8(8). DOI: 10.4161/epi.25440
Source: PubMed

ABSTRACT Glioblastoma multiforme (GBM) is the most common malignant adult brain tumor. Standard GBM treatment includes maximal safe surgical resection with combination radiotherapy and adjuvant temozolomide (TMZ) chemotherapy. Alarmingly, patient survival at five-years is below 10%. This is in part due to the invasive behavior of the tumor and the resulting inability to resect greater than 98% of some tumors. In fact, recurrence after such treatment may be inevitable, even in cases where gross total resection is achieved. The Cancer Genome Atlas (TCGA) research network performed whole genome sequencing of GBM tumors and found that GBM recurrence is linked to epigenetic mechanisms and pathways. Central to these pathways are epigenetic enzymes, which have recently emerged as possible new drug targets for multiple cancers, including GBM. Here we review GBM treatment, and provide a systems approach to identifying epigenetic drivers of GBM tumor progression based on temporal modeling of putative GBM cells of origin. We also discuss advances in defining epigenetic mechanisms controlling GBM initiation and recurrence and the drug discovery considerations associated with targeting epigenetic enzymes for GBM treatment.

0 Bookmarks
 · 
123 Views
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Romo1 is a mitochondrial protein whose elevated expression is commonly observed in various types of human cancers. However, the expression status of Romo1 and its implication in the pathogenesis of human glioblastoma (GBM) remain largely undefined. To understand the role of Romo1 in the progression of GBM, we explored its expression in a series of GBM tissues and cell lines and determined its effect on ROS production, cell proliferation, and tumor growth. Romo1 was frequently overexpressed at the mRNA level in both primary tumors and cell lines and its elevation was more commonly observed in high grade tumors versus low grade tumors. Romo1 expression was associated with ROS production and its knockdown led to a marked reduction of in vitro cellular growth and anchorage-independent growth of GBM. Consistently, Romo1 depletion induced a G2/M arrest of the cell cycle that was accompanied with accumulation of phospho-cdc2. Furthermore, a mouse xenograft assay revealed that Romo1 depletion significantly decreased tumor formation and growth. Therefore, our data demonstrate that Romo1 upregulation is a common event in human GBMs and contributes to the malignant tumor progression, suggesting that Romo1 could be a new therapeutic target for human GBM.
    Journal of Neuro-Oncology 09/2014; 121(1). DOI:10.1007/s11060-014-1608-x · 3.12 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: Glioblastoma multiforme (GBM) is the most frequent and malignant astrocytic glioma in the adult, with a survival rate at 5years less than 5%. In the GBM pathogenesis, the importance of genes methylation involved in cell cycle, tumor suppression, DNA repair and genome integrity, as well as tumor invasion and apoptosis has been described. We analyzed epigenetic regulation involvement of two genes related with apoptosis: TIMP3 and RUNX3 in order to define a clinical profile and compare with the most studied gene in GBM: MGMT. Eighty samples from GBM patients were evaluated by methylation specific PCR (MSP). Data from each patient were collected from medical histories to relate survival rates with gene methylation patterns. Methylation percentages obtained were: MGMT 45%, RUNX3 30% and TIMP3 28%. The study of MGMT methylation had prognostic value in patients with glioblastoma multiforme because at 8months, 28% of patients survived with the gene methylated, while none of them lived with the gene unmethylated (P=0.016). RUNX3 behavior was opposite to TIMP3 and MGMT. TIMP3action, in terms of patient's survival, was similar to that observed with MGMT, percentage of patients surviving at 8months with the gene methylated was 27%, compared with 7% of those with the unmethylated gene; there being a tendency to statistical significance (p=0.09). Copyright © 2014 Elsevier B.V. All rights reserved.
    Journal of the Neurological Sciences 11/2014; 347(1-2):325-331. DOI:10.1016/j.jns.2014.10.043 · 2.26 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Patient specific therapy is emerging as an important possibility for many cancer patients. However, to identify such therapies it is essential to determine the genomic and transcriptional alterations present in one tumor relative to control samples. This presents a challenge since use of a single sample precludes many standard statistical analysis techniques. We reasoned that one means of addressing this issue is by comparing transcriptional changes in one tumor with those observed in a large cohort of patients analyzed by The Cancer Genome Atlas (TCGA). To test this directly, we devised a bioinformatics pipeline to identify differentially expressed genes in tumors resected from patients suffering from the most common malignant adult brain tumor, glioblastoma (GBM). We performed RNA sequencing on tumors from individual GBM patients and filtered the results through the TCGA database in order to identify possible gene networks that are overrepresented in GBM samples relative to controls. Importantly, we demonstrate that hypergeometric-based analysis of gene pairs identifies gene networks that validate experimentally. These studies identify a putative workflow for uncovering differentially expressed patient specific genes and gene networks for GBM and other cancers.
    PLoS ONE 12/2014; 9(12):e115842. DOI:10.1371/journal.pone.0115842 · 3.53 Impact Factor

Full-text (3 Sources)

Download
40 Downloads
Available from
Dec 10, 2014