Abstract
Rapamycin, an inhibitor of mTOR, is in clinical trials for treatment of cancer. Rapamycin resistance has been reported in human breast epithelial tumor cells. Rapamycin effects on mTOR signaling and resistance were examined using benign, premalignant and tumor human breast epithelial cells. Rapamycin inhibition of cell proliferation, the cell cycle and mTOR signaling, including p70S6 and S6RP phosphorylation, was most effective in benign (MCF10A) and premalignant (MCF10AT; MCF10ATG3B) human breast epithelial cells, relative to MCF10CA1a tumor cells. Rapamycin resistance was reflected by reduced inhibition of p70S6K and S6RP phosphorylation in MCF10CA1a tumor cells, with RS6P showing the least response to rapamycin in the tumor cells. Rapamycin differentially inhibited STAT3 phosphorylation in this cell lineage. These data suggest that inhibition of mTOR signaling and STAT3 phosphorylation in benign and premalignant cells may be effective in the treatment of proliferative breast disease (PBD) and in the prevention of tumorigenesis and tumor recurrence.
- Rapamycin
- mTOR signaling
- mTOR phosphorylation
- STAT3 phosphorylation
- biomarkers of resistance
- p70S6 and RS6P
- human breast epithelial cells
- human breast premalignant and tumor epithelial cells
- early events in breast tumorigenesis
Footnotes
- Copyright© 2009 International Institute of Anticancer Research (Dr. John G. Delinassios), All rights reserved