Evidence for rearrangement, amplification, and expression of c-myc in a human glioblastoma.

Abstract

Amplified cellular genes are frequently manifested in one of two cytologically recognizable forms, double minutes or homogeneously staining regions. Additionally, evidence is accumulating that aberrant expression of cellular genes (including oncogenes) may be mediated by gene amplification. We now describe the amplification and expression of the cellular oncogene c-myc in double-minute-containing cells from a patient with glioblastoma multiforme, and we have shown that the amplification is associated with rearrangement of the c-myc gene. This finding further supports the common association of the myc gene family in neurogenic tumors and provides evidence of myc gene amplification in human brain cancer.Amplification of sequences related to cellular oncogenes has been described in several primary human tumors (1-3) as well as established tumor cell lines (1,4,5). Recent studies have demonstrated that amplification of the cellular homologue of the avian erythroblastosis virus oncogene (the receptor for epidermal growth factor) occurs in up to 40% of brain tumors of glial origin (3). The postulate that cellular oncogenes contribute to neoplastic growth (for review see ref. 6) and the knowledge that expression of these cellular genes can be dramatically altered by their amplification warrant further study of oncogene amplification in nervous system tumors.One element common to analysis of amplified DNA domains is the consistent finding of cytologically recognizable chromosome change associated with the amplification event. The finding of double minutes (DMs) (7) or homogeneously staining regions (HSRs) (4, 22) is a significant indicator of DNA sequence amplification and is increasingly being recognized as a common feature of many malignant human tumors. In detailed analysis of amplification of cellular genes in drug-resistant cell populations, it has become clear through molecular analysis of DM-enriched fractions (7) or in situ hybridization to 8,23) that these aberrations reflect the chromosomal sites of DNA sequence amplification. We have sought to take advantage of this finding by "pre-selecting" cell populations for molecular biological analysis on the basis of tumor karyotype. Tumors with cytologic evidence of amplification are then screened with the technique of DNA renaturation in agarose gels to positively detect amplified sequences. Finally, tumors that show signs of amplification in the above assay are analyzed for amplification of known oncogenes. In this report, we have used the above approach to show that a rearranged c-myc oncogene is amplified in DM-containing cells derived from a patient with glioblastoma multiforme. MATERIALS AND METHODSTumor Cells. Culture SF-188 originated on March 31, 1980, from a biopsy sample of a right frontal brain tumor in an 8-year-old boy with no family history of neoplastic or hereditary disease. The histological features of the tumor were characteristic of a glioblastoma multiforme with nuclear and cytoplasmic atypia and pleomorphism, increased cellularity, mitos...

Failure of central nervous system myelination in MBP/c-myc transgenic mice: evidence for c-myc cytotoxicity

“…Expression of the proto-oncogene c-myc has been linked to the development of both undi erentiated and di erentiated glial cell tumors (Trent et al, 1986;LaRocca et al, 1989;MacGregor and Zi , 1990;Radner et al, 1993;Hirvonen et al, 1994;Chattopadhyay et al, 1995). Oligo-astrocytomas (mixed gliomas) are brain tumors composed of a mixture of astrocytes and oligodendrocytes.…”

“…Most neuroectodermal tumors in the mature human brain are of astrocytic origin and in anaplastic variants, such as glioblastoma multiforme, overexpression of the cellular oncogene c-myc is common (Trent et al, 1986). The relatively low frequency of oligodendrocytic tumors indicates that oligodendrocytes are more resistant to neoplastic transformation than astrocytes.…”

Transcriptional regulation of the human osteopontin promoter: functional analysis and DNA-protein interactions

“…Further suggestion of a role for Myc in regulating OPN gene transcription comes from prior studies with quail chondrocytes which indicated that constitutive expression of the v-myc oncogene increased OPN mRNA levels (Castagnola et al, 1991). Interestingly, several studies suggest that increased expression of Myc protein is a marker of the most malignant astrocytic tumors (Trent et al, 1986;Ehgelhard et al, 1989;Orian et al, 1992). This is likely due to ampli®cation of the myc gene, which is reported to occur in the highest grade of malignant astrocytoma (glioblastoma) (Trent et al, 1986;Ehgelhard et al, 1989;Orian et al, 1992).…”

“…Interestingly, several studies suggest that increased expression of Myc protein is a marker of the most malignant astrocytic tumors (Trent et al, 1986;Ehgelhard et al, 1989;Orian et al, 1992). This is likely due to ampli®cation of the myc gene, which is reported to occur in the highest grade of malignant astrocytoma (glioblastoma) (Trent et al, 1986;Ehgelhard et al, 1989;Orian et al, 1992). Furthermore, antisense oligonucleotides directed toward myc have been reported to signi®cantly inhibit the growth of malignant astrocytoma cells in vitro, suggesting a critical role for Myc in the proliferation of these tumors (Broaddus et al, 1997).…”

“…Analysis of transcription factor binding to RE-1a and RE-1b elements by antibody supershift/blocking assays Analysis of Myc binding to RE-1a Increased Myc protein expression is a marker of the most malignant astrocytic tumors (Trent et al, 1986;Ehgelhard et al, 1989;Orian et al, 1992). Therefore, we used a monoclonal antibody directed toward Myc in gel shift assays to investigate whether the myc transcription factor binds RE-1a (Figure 4).…”