PMID- 16185816
OWN - NLM
STAT- MEDLINE
DCOM- 20051213
LR  - 20131121
IS  - 0361-090X (Print)
IS  - 0361-090X (Linking)
VI  - 29
IP  - 5
DP  - 2005
TI  - Inhibition of DNA methyltransferase reverses cisplatin induced drug resistance in 
      murine neuroblastoma cells.
PG  - 456-63
AB  - BACKGROUND: Acquired drug resistance is a major obstacle to the successful 
      treatment of neuroblastoma by chemotherapy. Recent studies from our laboratory 
      have demonstrated that drug-induced alterations in DNA methylation play an 
      important role in this process. METHODS: The reversal of resistance to cisplatin 
      in murine neuroblastoma (MNB) was induced by inhibition of DNA methyltransferase 
      activity. MNB cells overexpressing DNA methyltransferase activity (Dnmt3a or 
      Dnmt3b) were established by stable co-transfection of wild type MNB cells with 
      plasmids containing Dnmt3a or Dnmt3b cDNA. Cytotoxic response (IC50), total DNA 
      methyltransferase activity and expression of Dnmt3a or Dnmt3b methyltransferase 
      were determined in Dnmt3a or Dnmt3b transfected MNB cells, respectively. RESULTS: 
      These data demonstrated that total DNA methyltransferase activity was increased 
      to 3-fold above controls (P<0.001) in cisplatin resistant MNB cells, 3-fold in 
      Dnmt3a and 4-fold in Dnmt3b transfected MNB cells. Western blot and RT-PCR data 
      confirmed a corresponding increase in Dnmt3a and 3b expression in cisplatin 
      resistant and transfected cells when compared with control MNB cells (P<0.001). 
      MNB clones overexpressing Dnmt3a or Dnmt3b proteins were resistant to cisplatin 
      treatment (10(-6) M). Incubation of cisplatin resistant, Dnmt3a or Dnmt3b 
      overexpressing MNB cells with 5'-azacytidine (5'-azaC), a methylation inhibitor 
      (2.5 microM) significantly decreased DNA methyltransferase activity, expression 
      of Dnmt3a and Dnmt3b proteins and mRNA levels of cisplatin resistant, Dnmt3a and 
      Dnmt3b transfected MNB cells. Cytotoxicity studies using the MTT assay 
      demonstrated that the sensitivity of cisplatin resistant, Dnmt3a and Dnmt3b 
      overexpressing MNB cells to cisplatin was increased 10-fold (P<0.001) following 
      5'-azaC treatment. CONCLUSIONS: These findings suggest that the overexpression of 
      DNA methyltransferase is associated with a cisplatin resistant phenotype in MNB 
      cells that may or may not be true in animal studies or in the clinical setup. 
      Thus, DNA methylation plays a central role in onset of drug resistance in 
      cisplatin resistant neuroblastoma cells in vitro.
FAU - Qiu, Yi-Yong
AU  - Qiu YY
AD  - Children's Memorial Research Center, Children's Memorial Hospital, Department of 
      Pediatrics, Feinberg School of Medicine, Northwestern University, 2300 Children's 
      Plaza, Mail Box # 224, Chicago, IL 60614-3394, USA.
FAU - Mirkin, Bernard L
AU  - Mirkin BL
FAU - Dwivedi, Rama S
AU  - Dwivedi RS
LA  - eng
PT  - Journal Article
PT  - Research Support, Non-U.S. Gov't
DEP - 20050923
PL  - England
TA  - Cancer Detect Prev
JT  - Cancer detection and prevention
JID - 7704778
RN  - 0 (Antineoplastic Agents)
RN  - EC 2.1.1.- (DNA Modification Methylases)
RN  - Q20Q21Q62J (Cisplatin)
SB  - IM
MH  - Animals
MH  - Antineoplastic Agents/*pharmacology
MH  - Blotting, Western
MH  - Cisplatin/*pharmacology
MH  - DNA Damage
MH  - DNA Modification Methylases/*antagonists & inhibitors/*genetics
MH  - DNA Repair
MH  - Drug Resistance, Neoplasm/genetics
MH  - Gene Expression Profiling
MH  - Mice
MH  - Neuroblastoma/*pathology
MH  - Phenotype
MH  - Reverse Transcriptase Polymerase Chain Reaction
MH  - Transfection
MH  - Tumor Cells, Cultured
EDAT- 2005/09/28 09:00
MHDA- 2005/12/15 09:00
CRDT- 2005/09/28 09:00
PHST- 2005/05/16 00:00 [accepted]
PHST- 2005/09/28 09:00 [pubmed]
PHST- 2005/12/15 09:00 [medline]
PHST- 2005/09/28 09:00 [entrez]
AID - S0361-090X(05)00075-9 [pii]
AID - 10.1016/j.cdp.2005.05.004 [doi]
PST - ppublish
SO  - Cancer Detect Prev. 2005;29(5):456-63. doi: 10.1016/j.cdp.2005.05.004. Epub 2005 
      Sep 23.