Mutation Screening of Her-2, N-ras and Nf1 Genes in Brain Tumor Biopsies.

BACKGROUND/AIM A deeper understanding of the complex molecular pathology of brain malignancies is needed in order to develop more effective and targeted therapies of these highly lethal disorders. In an effort to further enlighten the molecular pathology of brain oncogenesis involving the her-2 (erbB-2/neu/ngl)/N-ras/nf1 pathway, we screened the genotypes of specimens from various types of brain tumors. MATERIALS AND METHODS The studied specimens included 35 biopsies of four general categories: 13 neuroglial tumors (4 astrocytomas, 2 oligodendrogliomas, 7 glioblastomas multiforme), 14 meningiomas, 3 other nervous system tumors (2 schwannomas, 1 craniopharyngioma) and 5 metastatic tumors (such as lung carcinomas and chronic myelocytic leukemia). Screening for most common mutations in oncogenes her-2, N-ras and tumor suppressor gene nf1 was conducted with molecular hybridization techniques (Southern blotting, dot blot and single-strand conformational polymorphism (SSCP) analysis, respectively), and was confirmed by DNA sequencing. RESULTS Gene amplification of her-2 was observed in only two cases (6%), namely in one glioblastoma and in one meningioma. Screening of 3 hot spot codons of the N-ras gene (12, 13 and 61) and subsequent DNA sequencing revealed mutations in 19 biopsies encompassing all categories (54%). Screening for mutations in exons of the nf1 gene by SSCP analysis detected a novel nonsense mutation in exon 31 in a unique case of a glioblastoma biopsy (3%) taken from a patient without neurofibromatosis type I. CONCLUSION Activated N-ras appears to be a major oncogene in brain oncogenesis, exhibiting the most important role in the her-2/N-ras/nf1 pathway.

[1]  D. Faller,et al.  Targeting the RAS oncogene , 2013, Expert opinion on therapeutic targets.

[2]  R. Neumann,et al.  Somatic mutations in the neurofibromatosis 1 gene in gliomas and primitive neuroectodermal tumours. , 1995, Anticancer research.

[3]  H. Lo.  Targeting Ras-RAF-ERK and its interactive pathways as a novel therapy for malignant gliomas. , 2010, Current cancer drug targets.

[4]  H. Schulten,et al.  Mutational screening of RET, HRAS, KRAS, NRAS, BRAF, AKT1, and CTNNB1 in medullary thyroid carcinoma. , 2011, Anticancer research.

[5]  Junshik Hong,et al.  N-ras Mutation Detection by Pyrosequencing in Adult Patients with Acute Myeloid Leukemia at a Single Institution , 2013, Annals of laboratory medicine.

[6]  Y. Yatabe,et al.  Japanese Society of Medical Oncology Clinical Guidelines: RAS (KRAS/NRAS) mutation testing in colorectal cancer patients11 , 2015, Cancer science.

[7]  R. Kurzrock,et al.  HER2 aberrations in cancer: implications for therapy. , 2014, Cancer treatment reviews.

[8]  L. Riley,et al.  A method for biotinylating oligonucleotide probes for use in molecular hybridizations. , 1986, DNA.

[9]  Alcino J. Silva,et al.  Neurofibromatosis Type 1: Modeling CNS Dysfunction , 2012, The Journal of Neuroscience.

[10]  T. Gazibara,et al.  The impact of TP53 and RAS mutations on cerebellar glioblastomas. , 2014, Experimental and molecular pathology.

[11]  S. Millis,et al.  HER2 expression status in diverse cancers: review of results from 37,992 patients , 2015, Cancer and Metastasis Reviews.

[12]  J. K. Cheong,et al.  The renewed battle against RAS-mutant cancers , 2016, Cellular and Molecular Life Sciences.

[13]  G. Reifenberger,et al.  Mutation analysis of the Ras pathway genes NRAS, HRAS, KRAS and BRAF in glioblastomas , 2004, Acta Neuropathologica.

[14]  Margaret Robertson,et al.  The neurofibromatosis type 1 gene encodes a protein related to GAP , 1990, Cell.

[15]  M. Wigler,et al.  Structure and activation of the human N-ras gene , 1983, Cell.

[16]  David B. Darr,et al.  Mutation-specific RAS oncogenicity explains NRAS codon 61 selection in melanoma. , 2014, Cancer discovery.

[17]  J. Boyd,et al.  Analysis of oncogene alterations in human endometrial carcinoma: Prevalence of ras mutations , 1991, Molecular carcinogenesis.

[18]  J. Schlegel,et al.  Targeting ErbB receptors in high-grade glioma. , 2011, Current pharmaceutical design.

[19]  Joshua M. Korn,et al.  Comprehensive genomic characterization defines human glioblastoma genes and core pathways , 2008, Nature.

[20]  H. Höfler,et al.  Ras gene mutations: a rare event in nonmetastatic primary malignant melanoma. , 1995, The Journal of investigative dermatology.

[21]  Juxiang Chen,et al.  The Challenges and the Promise of Molecular Targeted Therapy in Malignant Gliomas1 , 2015, Neoplasia.

[22]  Daniel J Brat,et al.  Molecular genetics of gliomas. , 2014, Cancer journal.

[23]  Dan Han,et al.  Increased wild-type N-ras activation by neurofibromin down-regulation increases human neuroblastoma stem cell malignancy. , 2011, Genes & cancer.

[24]  C. McPherson,et al.  Whole genome sequencing of glioblastoma multiforme identifies multiple structural variations involved in EGFR activation. , 2014, Mutagenesis.