PMID- 12479369
OWN - NLM
STAT- MEDLINE
DCOM- 20030113
LR  - 20200930
IS  - 1535-7163 (Print)
IS  - 1535-7163 (Linking)
VI  - 1
IP  - 9
DP  - 2002 Jul
TI  - Mechanisms of resistance to 1,3-bis(2-chloroethyl)-1-nitrosourea in human 
      medulloblastoma and rhabdomyosarcoma.
PG  - 727-36
AB  - 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.
FAU - Bacolod, Manny D
AU  - Bacolod MD
AD  - Department of Surgery, Duke University Medical Center, Durham, NC 27710, USA.
FAU - Johnson, Stewart P
AU  - Johnson SP
FAU - Ali-Osman, Francis
AU  - Ali-Osman F
FAU - Modrich, Paul
AU  - Modrich P
FAU - Bullock, Nancy S
AU  - Bullock NS
FAU - Colvin, O Michael
AU  - Colvin OM
FAU - Bigner, Darell D
AU  - Bigner DD
FAU - Friedman, Henry S
AU  - Friedman HS
LA  - eng
GR  - 2 R01-NS-30245/NS/NINDS NIH HHS/United States
GR  - 5P50 NS-20023/NS/NINDS NIH HHS/United States
GR  - R01-CA-82785/CA/NCI NIH HHS/United States
PT  - Journal Article
PT  - Research Support, U.S. Gov't, P.H.S.
PL  - United States
TA  - Mol Cancer Ther
JT  - Molecular cancer therapeutics
JID - 101132535
RN  - EC 2.1.1.63 (O(6)-Methylguanine-DNA Methyltransferase)
RN  - EC 2.5.1.18 (Glutathione Transferase)
RN  - GAN16C9B8O (Glutathione)
RN  - U68WG3173Y (Carmustine)
SB  - IM
MH  - Amino Acid Sequence
MH  - Apoptosis
MH  - Carmustine/*pharmacology
MH  - Cloning, Molecular
MH  - Dose-Response Relationship, Drug
MH  - Down-Regulation
MH  - *Drug Resistance, Neoplasm
MH  - *Gene Expression
MH  - Glutathione/metabolism
MH  - Glutathione Transferase/metabolism
MH  - Humans
MH  - Medulloblastoma/*drug therapy
MH  - Molecular Sequence Data
MH  - O(6)-Methylguanine-DNA Methyltransferase/metabolism
MH  - Point Mutation
MH  - Rhabdomyosarcoma/*drug therapy
MH  - Sequence Homology, Amino Acid
MH  - Time Factors
MH  - Up-Regulation
EDAT- 2002/12/14 04:00
MHDA- 2003/01/14 04:00
CRDT- 2002/12/14 04:00
PHST- 2002/12/14 04:00 [pubmed]
PHST- 2003/01/14 04:00 [medline]
PHST- 2002/12/14 04:00 [entrez]
PST - ppublish
SO  - Mol Cancer Ther. 2002 Jul;1(9):727-36.