Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: UMLS:C0017638 (glioma)
 30,880 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The ARHI (aplasia Ras homologue member I, also known as DIRAS3) gene shows 60.0% sequence homology to the Ras proto-oncogene and was the first mater-nally-imprinted tumor suppressor gene identified in the Ras family. It is constitutively expressed from the paternal allele in normal breast, ovary, heart, liver, pancreas, thyroid and brain tissues, and is lost or markedly down-regulated primarily in breast, ovarian, pancreas and thyroid tumor tissues. We have investigated the expression, LOH (loss of heterozygosity) and methylation status of this gene in glial tumors and peripheral blood samples of 21 patients, and in seven normal brain tissue samples. Gene expression by real time reverse transcriptase polymerase chain reaction (RT-PCR) was found to be increased in 14 and decreased in seven of the 21 tumors. The LOH was detected by fragment analysis, using five labeled polymorphic markers specific for the 1p31 region, in two of the tumors. Methylation status of the CpG island I, II and III was evaluated using COBRA (combined bisulfite restriction analysis) and RFLP (restriction fragment length polymorphism) in 21 tumors and also a hypermethylated healthy volunteer as a positive control, revealed that only two tumors had hypermethylation in CpG island I (of which one also had LOH). These results suggest that LOH and hypermethylation may be one mechanism of silencing the ARHI gene expression and development of glial tumor development.
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PMID:Aplasia ras homologous member I gene and development of glial tumors. 2405 1

Epidermal growth factor receptor (EGFR)-Akt signaling cascade activation plays a pivotal role in gliomas malignant phenotype, especially in Classical and Mesenchymal subtype gliomas. However, the molecules and mechanisms underlying regulate and maintain the activation of EGFR-AKT signaling remains unclear. Previously reports showed that DIRAS3 inhibits cell proliferation and induces autophagy in ovarian, breast, lung and prostate cancers, which is heterozygosity loss or down-regulated in aforementioned cancers and functionally as a tumor suppressor, whereas the role of DIRAS3 in glioma is still veiled. Here, in this study, we investigated the biological function and role of DIRAS3 in gliomas, and found that DIRAS3 is up-regulated in gliomas and is positively correlated with poor prognosis of glioma patients, meanwhile, over-expressed DIRAS3 promotes glioma cells proliferation and invasion. Further mechanistic study showed that the expression level of DIRAS3 in Classical and Mesenchymal subtype GBMs is higher, and over-expression of DIRAS3 promotes EGFR-AKT signaling activation at the downstream of EGFR and increases AKT phosphorylation, meanwhile suppression of AKT by MK-2206 reverses the tumor promoting function of DIRAS3. Taken together, these findings reveal a novel oncogenic role of DIRAS3 in the development and progression of glioma, which suggest that DIRAS3 could serve as a potential diagnostic marker and a promising therapeutic target of gliomas.
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PMID:Oncogenic DIRAS3 promotes malignant phenotypes of glioma by activating EGFR-AKT signaling. 3026 4

Epidermal growth factor receptor variant III (EGFRvIII) is a tumor-specific mutation widely expressed in glioma. However, its role and molecular mechanism in glioma have not been completely elucidated. Immunohistochemistry analyses of EGFRvIII, enhancer of zeste homolog 2 (EZH2) and aplysia ras homolog I (ARHI) were performed in tumor tissues from patients with glioma. Regulatory mechanisms among EGFRvIII, EZH2 and ARHI were examined by western blot and chromatin immunoprecipitation (ChIP). Cell proliferation and migration of glioma cells were examined. EGFRvIII and EZH2 expression were upregulated, while ARHI was downregulated in glioma tissues. EZH2 knockdown increased ARHI expression in glioma cell lines. ChIP assay suggested that EZH2 was enriched in the ARHI promoter. Furthermore, ectopic expression of EGFRvIII upregulated EZH2, suppressed ARHI expression, and promoted glioma cell proliferation. Additionally, treatment with 3-deazaneplanocin A (DZNep, an inhibitor of EZH2) inhibited expression of EZH2, increased protein level of ARHI, and partially abrogated the promoting effects of ARHI knockdown on glioma cell proliferation and migration. In summary, EGFRvIII-mediated epigenetic suppression of ARHI promoted glioma cell proliferation and migration via upregulating EZH2.
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PMID:EGFRvIII epigenetically regulates ARHI to promote glioma cell proliferation and migration. 3175 60

Hypermethylation can downregulate many tumor suppressor gene expressions. Aplasia Ras homologue member I (ARHI, DIRAS3) is one of the maternally imprinted tumor suppressors in the RAS superfamily. This chapter overviewed the importance of ARHI methylation and expression phenomes in various types of cancers, although the exact mechanisms remain unclear. As an imprinted gene, aberrant DNA methylation of the paternal allele of ARHI was identified as a primary inhibitor of ARHI expression. The role of methylation in the CpG islands of the ARHI promoter region vary among ovarian cancers, breast cancers, hepatocellular carcinoma, colon cancers, pancreatic cancer osteosarcoma, glial tumors, follicular thyroid carcinoma, or lung cancers. The methylation of ARHI provides a new insight to understand molecular mechanisms of tumorigenesis and progression of cancers.
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PMID:The Role of Methylation in the CpG Island of the ARHI Promoter Region in Cancers. 3294 95