Identification of nitrosourea-resistant human rhabdomyosarcomas by in situ immunostaining of O6-methylguanine-DNA methyltransferase.

Published

Journal Article

Cellular levels of O6-methylguanine-DNA methyltransferase (MGMT) correlate strongly with cellular resistance to carcinogenic and chemotherapeutic agents that produce adducts at the O6-position of guanine in DNA. Although biochemical and molecular assays can indicate the average MGMT content of tissues or tumors, they cannot distinguish mixed populations of cells, such as those that exist in tumor biopsy samples. We have determined MGMT at the cellular level in a panel of pediatric rhabdomyosarcoma xenografts by in situ immunostaining with a human MGMT-specific antibody employing a very sensitive procedure that involves biotin-avidin coupled horseradish peroxidase with silver-enhanced diaminobenzidine-nickel staining. Two xenograft tumor lines known to be MGMT-deficient were not stained, whereas the nuclei in three MGMT-expressing lines were clearly stained. This is the first demonstration of an in situ procedure that discriminates drug-sensitive MGMT-deficient tumors from drug-resistant MGMT expressing tumors. This procedure should prove useful, therefore, for predicting the susceptibility of tissues and tumors to O6-guanine alkylating agents.

Full Text

Duke Authors

Cited Authors

  • Brent, TP; von Wronski, MA; Edwards, CC; Bromley, M; Margison, GP; Rafferty, JA; Pegram, CN; Bigner, DD

Published Date

  • January 1, 1993

Published In

Volume / Issue

  • 5 / 2

Start / End Page

  • 83 - 86

PubMed ID

  • 8364257

Pubmed Central ID

  • 8364257

Electronic International Standard Serial Number (EISSN)

  • 1555-3906

International Standard Serial Number (ISSN)

  • 0965-0407

Language

  • eng