Altered expression of the DNA repair protein, N-methylpurine-DNA glycosylase (MPG) in breast cancer.
We examined expression of N-methylpurine-DNA glycosylase (MPG), a DNA repair enzyme that removes N-alkylpurine damage, in normal, malignant, and immortalized breast epithelial cells, and breast cancer cell lines (MDA-MB-231, MCF7, T47D). Northern analysis showed increased expression in cancer versus normal breast epithelial cells (2-24-fold). Southern blots revealed no gene amplification or polymorphisms. Immunofluorescence, immunohistochemistry, and Western blot analysis demonstrated increased MPG protein expression in the tumor cells that correlated with elevated glycosylase activity. Since MPG overexpression has been shown to be paradoxically associated with increased susceptibility to DNA damage, up-regulation of this gene may suggest a functional role in breast carcinogenesis.
Department of Medicine, Northwestern University Cancer Center, Chicago, IL 60611, USA.
S R
SR
Cerda
P W
PW
Turk
A D
AD
Thor
S A
SA
Weitzman
D000225:Adenine / Q000031:analogs & derivatives / Q000378:metabolism; D000595:Amino Acid Sequence; D001940:Breast / Q000378:metabolism; D001943:Breast Neoplasms / Q000201:enzymology* / Q000235:genetics; D002478:Cells, Cultured; D045647:DNA Glycosylases; D004260:DNA Repair; D006801:Humans; D008969:Molecular Sequence Data; D009699:N-Glycosyl Hydrolases / Q000096:biosynthesis* / Q000378:metabolism; D012333:RNA, Messenger / Q000378:metabolism; D014407:Tumor Cells, Cultured
D012333:RNA, Messenger; C004981:1,N(6)-ethenoadenine; D045647:DNA Glycosylases; D009699:N-Glycosyl Hydrolases; C076131:DNA-3-methyladenine glycosidase II; D000225:Adenine