MGMT immunohistochemical expression and promoter methylation in human glioblastoma

Fausto J. Rodriguez, Stephen N Thibodeau, Robert Brian Jenkins, Karen V. Schowalter, Bolette L. Caron, Brian Patrick O'Neill, Charles David James, Sandra Passe, Jeff Slezak, Caterina Giannini

Research output: Contribution to journalArticle

106 Citations (Scopus)

Abstract

O6-methylguanine-DNA methyltransferase (MGMT) expression has been recently proposed as a useful prognostic and/or predictive marker in glioblastoma patients receiving adjuvant therapy after the surgery. We studied samples from 50 patients with histologically confirmed GBM to evaluate MGMT expression by immunohistochemistry and its relation to promoter methylation status. Genomic DNA was extracted from scrapings of formalin-fixed, paraffin-embedded tissue corresponding to hematoxylin and eosin sections. Using the mouse monoclonal antibody MT3.1, MGMT expression was assessed and scored in tumor cells: (1=negative or limited to <10% positive tumor cells, 2=10% to 50%, 3=>50%). Methylation-specific polymerase chain reaction was performed after bisulfite treatment. Assessment of MGMT expression in neoplastic tissue required careful scrutiny because of its expression in a variety of non-neoplastic cells. MGMT expression was present in tumor cells with a score of 1, 2, and 3, respectively in 36 (72%), 13 (26%), and 1 (2%) cases. Methylation-specific polymerase chain reaction yielded interpretable results in 39 cases (78%). MGMT promoter methylation was detected in 15 cases (38.5%), whereas 24 (61.5%) were unmethylated. Among the methylated samples, 14 (of 15) had a score of 1, and 1 had a score of 3 by immunohistochemistry. Of the 24 unmethylated samples, 18 had a score of 1, and 6 of 2. There was no significant correlation between MGMT expression and methylation, and no significant survival difference was observed between patients whose tumors were negative versus positive for MGMT protein by immunohistochemistry. This study underscores some of the difficulties in applying immunohistochemistry to assess MGMT expression.

Original languageEnglish (US)
Pages (from-to)59-65
Number of pages7
JournalApplied Immunohistochemistry and Molecular Morphology
Volume16
Issue number1
DOIs
StatePublished - Jan 2008

Fingerprint

Methyltransferases
Glioblastoma
Methylation
DNA
Immunohistochemistry
Protein Methyltransferases
Neoplasms
Polymerase Chain Reaction
Hematoxylin
Eosine Yellowish-(YS)
Paraffin
Formaldehyde
Monoclonal Antibodies
Survival

Keywords

  • DNA methylation
  • Glioblastoma
  • Immunohistochemistry
  • MGMT
  • O6-methylguanine-DNA methyltransferase

ASJC Scopus subject areas

  • Anatomy
  • Medical Laboratory Technology

Cite this

MGMT immunohistochemical expression and promoter methylation in human glioblastoma. / Rodriguez, Fausto J.; Thibodeau, Stephen N; Jenkins, Robert Brian; Schowalter, Karen V.; Caron, Bolette L.; O'Neill, Brian Patrick; David James, Charles; Passe, Sandra; Slezak, Jeff; Giannini, Caterina.

In: Applied Immunohistochemistry and Molecular Morphology, Vol. 16, No. 1, 01.2008, p. 59-65.

Research output: Contribution to journalArticle

Rodriguez, Fausto J. ; Thibodeau, Stephen N ; Jenkins, Robert Brian ; Schowalter, Karen V. ; Caron, Bolette L. ; O'Neill, Brian Patrick ; David James, Charles ; Passe, Sandra ; Slezak, Jeff ; Giannini, Caterina. / MGMT immunohistochemical expression and promoter methylation in human glioblastoma. In: Applied Immunohistochemistry and Molecular Morphology. 2008 ; Vol. 16, No. 1. pp. 59-65.
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