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Mechanisms of resistance to 1,3-bis(2-chloroethyl)-1-nitrosourea in human medulloblastoma and rhabdomyosarcoma.

Publication ,  Journal Article
Bacolod, MD; Johnson, SP; Ali-Osman, F; Modrich, P; Bullock, NS; Colvin, OM; Bigner, DD; Friedman, HS
Published in: Mol Cancer Ther
July 2002

Medulloblastoma (D-341 MED) and rhabdomyosarcoma (TE-671) cell lines, which are resistant to either 1,3-bis(2-chloroethyl)-1-nitrosourea (BCNU) or the combination of BCNU and O6-benzylguanine (O6-BG), were generated by serial escalation of BCNU. The activities of O6-alkylguanine-DNA alkyltransferase (AGT), glutathione-S-transferase (GST), and total glutathione (GSH) of the parental, BCNU-resistant (BR), and BCNU + O6-BG-resistant (OBR) cells were measured. No significant differences in GST activity or total GSH were seen between the parental, BR, and OBR cells of both TE-671 and D-341 MED. The AGT activities of D-341 MED (BR) and TE-671 (BR) were twice those of D-341 MED and TE-671, respectively, confirming the importance of this enzyme for BCNU resistance. The D-341 MED (OBR) cells did not exhibit any AGT activity, suggesting that another mechanism must play a role in the drug resistance. Fewer DNA interstrand cross-links (ICLs) were observed in D-341 MED (OBR) than in D-341 MED after 8 h BCNU (100-400 microM) treatment. However, the amounts of DNA ICLs observed in D-341 MED and D-341 MED (OBR) were stable after 24 h. Microarray analysis showed the increased expressions of several metallothionein genes and down-regulation of several proapoptotic genes. The AGT activity of TE-671 (OBR) was 223 fmol/mg when the cells were grown in 10 microM O6-BG and decreased to about half this value when the O6-BG concentration was increased 60 microM. The AGT cDNA of TE-671 (OBR) cells was cloned and found to contain a G-to-T transversion at codon 156, resulting in conversion of glycine to cysteine (G156C). In vitro mutagenesis has shown that the G156C AGT mutant is resistant to inactivation by O6-BG. Thus, the selection of a mutant AGT with decreased sensitivity to O6-BG is a significant contributing factor to BCNU + O6-BG resistance.

Duke Scholars

Published In

Mol Cancer Ther

ISSN

1535-7163

Publication Date

July 2002

Volume

1

Issue

9

Start / End Page

727 / 736

Location

United States

Related Subject Headings

  • Up-Regulation
  • Time Factors
  • Sequence Homology, Amino Acid
  • Rhabdomyosarcoma
  • Point Mutation
  • Oncology & Carcinogenesis
  • O(6)-Methylguanine-DNA Methyltransferase
  • Molecular Sequence Data
  • Medulloblastoma
  • Humans
 

Citation

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ICMJE
MLA
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Bacolod, M. D., Johnson, S. P., Ali-Osman, F., Modrich, P., Bullock, N. S., Colvin, O. M., … Friedman, H. S. (2002). Mechanisms of resistance to 1,3-bis(2-chloroethyl)-1-nitrosourea in human medulloblastoma and rhabdomyosarcoma. Mol Cancer Ther, 1(9), 727–736.
Bacolod, Manny D., Stewart P. Johnson, Francis Ali-Osman, Paul Modrich, Nancy S. Bullock, O Michael Colvin, Darell D. Bigner, and Henry S. Friedman. “Mechanisms of resistance to 1,3-bis(2-chloroethyl)-1-nitrosourea in human medulloblastoma and rhabdomyosarcoma.Mol Cancer Ther 1, no. 9 (July 2002): 727–36.
Bacolod MD, Johnson SP, Ali-Osman F, Modrich P, Bullock NS, Colvin OM, et al. Mechanisms of resistance to 1,3-bis(2-chloroethyl)-1-nitrosourea in human medulloblastoma and rhabdomyosarcoma. Mol Cancer Ther. 2002 Jul;1(9):727–36.
Bacolod, Manny D., et al. “Mechanisms of resistance to 1,3-bis(2-chloroethyl)-1-nitrosourea in human medulloblastoma and rhabdomyosarcoma.Mol Cancer Ther, vol. 1, no. 9, July 2002, pp. 727–36.
Bacolod MD, Johnson SP, Ali-Osman F, Modrich P, Bullock NS, Colvin OM, Bigner DD, Friedman HS. Mechanisms of resistance to 1,3-bis(2-chloroethyl)-1-nitrosourea in human medulloblastoma and rhabdomyosarcoma. Mol Cancer Ther. 2002 Jul;1(9):727–736.

Published In

Mol Cancer Ther

ISSN

1535-7163

Publication Date

July 2002

Volume

1

Issue

9

Start / End Page

727 / 736

Location

United States

Related Subject Headings

  • Up-Regulation
  • Time Factors
  • Sequence Homology, Amino Acid
  • Rhabdomyosarcoma
  • Point Mutation
  • Oncology & Carcinogenesis
  • O(6)-Methylguanine-DNA Methyltransferase
  • Molecular Sequence Data
  • Medulloblastoma
  • Humans