Multiple DNA repair mechanisms and alkylator resistance in the human medulloblastoma cell line D-283 Med (4-HCR).

Published

Journal Article

PURPOSE: We have previously reported preferential repair of DNA interstrand crosslinks in the 4-hydroperoxycyclophosphamide-resistant human medulloblastoma cell line D-283 Med (4-HCR). We now report further studies that explored the potential mechanisms underlying this repair. METHODS: Limiting dilution assays and Western, Southern, and Northern blots were used to compare specific differences between D-283 Med (4-HCR) and its parental line D-283 Med. RESULTS: D-283 Med (4-HCR) was cross-resistant to melphalan and 1,3-bis(2-chloroethyl)-1-nitrosourea (BCNU), with O6-alkylguanine-DNA alkyltransferase (AGT) levels of 466+/-164 fmol/mg protein; AGT levels in the parental line, D-283 Med, were 76+/-96 fmol/mg. The increase in AGT activity was not a result of gene amplification. Depleting AGT with O6-benzylguanine partially restored sensitivity to BCNU. Both cell lines were deficient in the human mismatch protein MutLalpha. ERCC4 mRNA and poly(ADP-ribose) polymerase levels were similar in both cell lines, and ERCC1 mRNA levels were 2- to 2.5-fold lower in D-283 Med (4-HCR). Topoisomerase I levels were 2- to 2.5-fold higher in D-283 Med compared with D-283 Med (4-HCR). CONCLUSION: These results, while illustrating the multiple differences between D-283 Med and D-283 Med (4-HCR), do not explain the enhanced DNA interstrand crosslink repair seen in D-283 Med (4-HCR).

Full Text

Duke Authors

Cited Authors

  • Dong, Q; Johnson, SP; Colvin, OM; Bullock, N; Kilborn, C; Runyon, G; Sullivan, DM; Easton, J; Bigner, DD; Nahta, R; Marks, J; Modrich, P; Friedman, HS

Published Date

  • 1999

Published In

Volume / Issue

  • 43 / 1

Start / End Page

  • 73 - 79

PubMed ID

  • 9923544

Pubmed Central ID

  • 9923544

International Standard Serial Number (ISSN)

  • 0344-5704

Digital Object Identifier (DOI)

  • 10.1007/s002800050865

Language

  • eng

Conference Location

  • Germany