title: Rapamycin resistance tied to defective regulation of p27Kip1.
abstract: The potent antiproliferative activity of the macrolide antibiotic rapamycin is known to involve binding of the drug to its cytosolic receptor, FKBP12, and subsequent interaction with targets of rapamycin, resulting in inhibition of p70 S6 kinase (p70S6K). However, the downstream events that lead to inhibition of cell cycle progression remain to be elucidated. The antiproliferative effects of rapamycin are associated with prevention of mitogen-induced downregulation of the cyclin-dependent kinase inhibitor p27Kip1, suggesting that the latter may play an important role in the growth pathway targeted by rapamycin. Murine BC3H1 cells, selected for resistance to growth inhibition by rapamycin, exhibited an intact p70S6K pathway but had abnormally low p27 levels that were no longer responsive to mitogens or rapamycin. Fibroblasts and T lymphocytes from mice with a targeted disruption of the p27Kip1 gene had impaired growth-inhibitory responses to rapamycin. These results suggest that the ability to regulate p27Kip1 levels is important for rapamycin to exert its antiproliferative effects.
authors.affiliation: Cell Biology Program and Howard Hughes Medical Institute, Memorial Sloan-Kettering Cancer Center, New York, New York 10021, USA.
authors.forename: Y
authors.initials: Y
authors.lastname: Luo
authors.forename: S O
authors.initials: SO
authors.lastname: Marx
authors.forename: H
authors.initials: H
authors.lastname: Kiyokawa
authors.forename: A
authors.initials: A
authors.lastname: Koff
authors.forename: J
authors.initials: J
authors.lastname: Massagué
authors.forename: A R
authors.initials: AR
authors.lastname: Marks
mesh_terms: D000818:Animals; D000903:Antibiotics, Antineoplastic / Q000494:pharmacology*; D018797:Cell Cycle Proteins; D002455:Cell Division / Q000187:drug effects; D002460:Cell Line; D050760:Cyclin-Dependent Kinase Inhibitor p27; D004352:Drug Resistance, Microbial / Q000235:genetics*; D005347:Fibroblasts / Q000166:cytology / Q000187:drug effects; D005786:Gene Expression Regulation / Q000187:drug effects*; D051379:Mice; D008869:Microtubule-Associated Proteins / Q000235:genetics*; D011090:Polyenes / Q000494:pharmacology*; D020123:Sirolimus; D013601:T-Lymphocytes / Q000166:cytology* / Q000187:drug effects; D025521:Tumor Suppressor Proteins
chemical_list: D000903:Antibiotics, Antineoplastic; C493961:Cdkn1b protein, mouse; D018797:Cell Cycle Proteins; D008869:Microtubule-Associated Proteins; D011090:Polyenes; D025521:Tumor Suppressor Proteins; D050760:Cyclin-Dependent Kinase Inhibitor p27; D020123:Sirolimus