title: Silibinin inhibits translation initiation: implications for anticancer therapy.
abstract: Silibinin is a nontoxic flavonoid reported to have anticancer properties. In this study, we show that silibinin exhibits antiproliferative activity on MCF-7 breast cancer cells. Exposure to silibinin leads to a concentration-dependent decrease in global protein synthesis associated with reduced levels of eukaryotic initiation factor 4F complex. Moreover, polysome profile analysis of silibinin-treated cells shows a decrease in polysome content and translation of cyclin D1 mRNA. Silibinin exerts its effects on translation initiation by inhibiting the mammalian target of rapamycin signaling pathway by acting upstream of TSC2. Our results show that silibinin blocks mammalian target of rapamycin signaling with a concomitant reduction in translation initiation, thus providing a possible molecular mechanism of how silibinin can inhibit growth of transformed cells.
authors.affiliation: McGill University, 3655 Promenade Sir William Osler, Montreal, Quebec, Canada.
authors.forename: Chen-Ju
authors.initials: CJ
authors.lastname: Lin
authors.forename: Rami
authors.initials: R
authors.lastname: Sukarieh
authors.forename: Jerry
authors.initials: J
authors.lastname: Pelletier
mesh_terms: D000970:Antineoplastic Agents / Q000494:pharmacology; D000975:Antioxidants / Q000494:pharmacology; D015153:Blotting, Western; D001943:Breast Neoplasms / Q000235:genetics / Q000378:metabolism / Q000473:pathology; D002453:Cell Cycle / Q000187:drug effects; D045744:Cell Line, Tumor; D002467:Cell Nucleus / Q000378:metabolism; D049109:Cell Proliferation / Q000187:drug effects*; D019938:Cyclin D1 / Q000235:genetics / Q000378:metabolism; D004305:Dose-Response Relationship, Drug; D039561:Eukaryotic Initiation Factor-4E / Q000378:metabolism; D039562:Eukaryotic Initiation Factor-4F / Q000378:metabolism; D005455:Fluorescent Antibody Technique; D006801:Humans; D000076222:Mechanistic Target of Rapamycin Complex 1; D046912:Multiprotein Complexes; D014176:Protein Biosynthesis / Q000187:drug effects*; D021381:Protein Transport / Q000187:drug effects; D011506:Proteins; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction; D015398:Signal Transduction / Q000187:drug effects; D000077385:Silybin; D012838:Silymarin / Q000494:pharmacology; D058570:TOR Serine-Threonine Kinases; D014157:Transcription Factors / Q000378:metabolism; D000077005:Tuberous Sclerosis Complex 2 Protein; D025521:Tumor Suppressor Proteins / Q000378:metabolism
chemical_list: D000970:Antineoplastic Agents; D000975:Antioxidants; D039561:Eukaryotic Initiation Factor-4E; D039562:Eukaryotic Initiation Factor-4F; D046912:Multiprotein Complexes; D011506:Proteins; D012333:RNA, Messenger; D012838:Silymarin; C000624653:TSC2 protein, human; D014157:Transcription Factors; D000077005:Tuberous Sclerosis Complex 2 Protein; D025521:Tumor Suppressor Proteins; D019938:Cyclin D1; D000077385:Silybin; D000076222:Mechanistic Target of Rapamycin Complex 1; D058570:TOR Serine-Threonine Kinases