Cellular levels of O6-methylguanine-DNA methyltransferase in mammary epithelial cells and liver from virgin, pregnant and pituitary grafted mice
- 1 October 1991
- journal article
- research article
- Published by Oxford University Press (OUP) in Carcinogenesis: Integrative Cancer Research
- Vol. 12 (10) , 1795-1800
- https://doi.org/10.1093/carcin/12.10.1795
Abstract
O6 methyltransferase (O6 is a DNA repair protein that reverses alkylation damage at the O6 position of guanine. In the process, O6-MT undergoes suicide inactivation. To determine if this enzyme might be regulated by pregnancy-associated hormones we measured changes in the level of O6-MT in isolated mouse mammary epithelial cell homogenates during different reproductive states. These were pregnancy, ectopic pituitary transplantation, proestrus/estrus and diestrus. O6 levels were found to be similar in mice in proestrus/estrus (0.95 fmolμg DNA) as compared to diestrus (0.94 fmol/μg DNA) and also mixed populations of virgin mice (1.09 fmol/μg DNA). A mean for all virgin mice (0.97 fmol/μg DNA) was i as a comparative Index. 0 decreased 2-fold during pregnancy in mammary epithelial cells to a mean value of 0.45 fmol/μg DNA (P < 0.05). A smaller decrease (0.65 fmol/μg DNA; P 6-MT increased in pregnant (5.3 fmol/μ DNA) and pituitary transplanted (3.9 fmol/μ DNA) mice, and were 5- and 4-fold higher than the concentration in virgin mammary epithelial cells respectively.Keywords
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