%0 Journal Article
%T Assessment of the proliferative, apoptotic and cellular renovation indices of the human mammary epithelium during the follicular and luteal phases of the menstrual cycle
%A Maria Navarrete
%A Carolina M Maier
%A Roberto Falzoni
%A Luiz Quadros
%A Geraldo R Lima
%A Edmund C Baracat
%A Afonso CP Naz¨¢rio
%J Breast Cancer Research
%D 2005
%I BioMed Central
%R 10.1186/bcr994
%X Normal breast tissue samples were obtained from 42 randomly selected patients in the proliferative (n = 21) and luteal (n = 21) phases. Menstrual cycle phase characterization was based on the date of the last and subsequent menses, and on progesterone serum levels obtained at the time of biopsy.The proliferation index (PI), defined as the number of Ki-67-positive nuclei per 1,000 epithelial cells, was significantly larger in the luteal phase (30.46) than in the follicular phase (13.45; P = 0.0033). The AI was defined as the number of TUNEL-positive cells per 1,000 epithelial cells. The average AI values in both phases of the menstrual cycle were not statistically significant (P = 0.21). However, the cell renewal index (CRI = PI/AI) was significantly higher in the luteal phase (P = 0.033). A significant cyclical variation of PI, AI and CRI was observed. PI and AI peaks occurred on about the 24th day of the menstrual cycle, whereas the CRI reached higher values on the 28th day.We conclude that proliferative activity is dependent mainly on hormonal fluctuations, whereas apoptotic activity is probably regulated by hormonal and non-hormonal factors.The cyclical transformations and cellular kinetics of the mammary gland have long been the subject of intense investigation. Interest in alterations caused by steroid actions, specifically on epithelial proliferation, has risen sharply in the past decade owing to increasing numbers of breast carcinomas in the female population [1]. There is also an immediate need for more accurate predictors of breast cancer risk, particularly in light of the various chemoprevention trials under way.Understanding the factors and mechanisms that regulate hormone-related changes in the normal human breast is crucial, because alterations in breast structure and function during the menstrual cycle could predispose this tissue to malignant changes and hence to the development of breast cancer. The present study focuses on epithelial cells, the prim
%K apoptosis
%K Ki-67
%K mammary gland
%K menstrual cycle
%K TdT-mediated dUTP nick end labeling
%U http://breast-cancer-research.com/content/7/3/R306