Rapamycin effects on mTOR signaling in benign, premalignant and malignant human breast epithelial cells.
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.
Kim
So Hee
SH
Wayne State University, Detroit, MI 48201, USA.
Zukowski
Kim
K
Novak
Raymond F
RF
D000903:Antibiotics, Antineoplastic / Q000494:pharmacology*; D001940:Breast / Q000187:drug effects*; D001943:Breast Neoplasms / Q000188:drug therapy* / Q000378:metabolism / Q000473:pathology; D002453:Cell Cycle / Q000187:drug effects; D049109:Cell Proliferation / Q000187:drug effects; D002478:Cells, Cultured; D005434:Flow Cytometry; D006801:Humans; D015151:Immunoblotting; D010766:Phosphorylation / Q000187:drug effects; D011230:Precancerous Conditions / Q000188:drug therapy* / Q000378:metabolism / Q000473:pathology; D011494:Protein Kinases / Q000378:metabolism*; D051057:Proto-Oncogene Proteins c-akt / Q000378:metabolism; D038762:Ribosomal Protein S6 Kinases, 70-kDa / Q000378:metabolism; D050794:STAT1 Transcription Factor / Q000378:metabolism; D015398:Signal Transduction / Q000187:drug effects; D020123:Sirolimus / Q000494:pharmacology*; D058570:TOR Serine-Threonine Kinases
D000903:Antibiotics, Antineoplastic; D050794:STAT1 Transcription Factor; C494079:STAT1 protein, human; D011494:Protein Kinases; C546842:MTOR protein, human; D051057:Proto-Oncogene Proteins c-akt; D038762:Ribosomal Protein S6 Kinases, 70-kDa; D058570:TOR Serine-Threonine Kinases; D020123:Sirolimus