title: Impact of pyrrolidine dithiocarbamate and interleukin-6 on mammalian target of rapamycin complex 1 regulation and global protein translation.
abstract: Interleukin-6 (IL-6) is a proinflammatory cytokine that exerts a wide range of cellular, physiological, and pathophysiological responses. Pyrrolidine dithiocarbamate (PDTC) antagonizes the cellular responsiveness to IL-6 through impairment in signal transducer and activator of transcription-3 activation and downstream signaling. To further elucidate the biological properties of PDTC, global gene expression profiling of human HepG2 hepatocellular carcinoma cells was carried out after treatment with PDTC or IL-6 for up to 8 h. Through an unbiased pathway analysis method, gene array analysis showed dramatic and temporal differences in expression changes in response to PDTC versus IL-6. A significant number of genes associated with metabolic pathways, inflammation, translation, and mitochondrial function were changed, with ribosomal protein genes and DNA damage-inducible transcript 4 protein (DDIT4) primarily up-regulated with PDTC but down-regulated with IL-6. Quantitative polymerase chain reaction and Western blot analyses validated the microarray data and showed the reciprocal expression pattern of the mammalian target of rapamycin (mTOR)-negative regulator DDIT4 in response to PDTC versus IL-6. Cell treatment with PDTC resulted in a rapid and sustained activation of Akt and subsequently blocked the IL-6-mediated increase in mTOR complex 1 function through up-regulation in DDIT4 expression. Conversely, down-regulation of DDIT4 with small interfering RNA dampened the capacity of PDTC to block IL-6-dependent mTOR activation. The overall protein biosynthetic capacity of the cells was severely blunted by IL-6 but increased in a rapamycin-independent pathway by PDTC. These results demonstrate a critical effect of PDTC on mTOR complex 1 function and provide evidence that PDTC can reverse IL-6-related signaling via induction of DDIT4.
authors.affiliation: Laboratory of Clinical Investigation, National Institute on Aging, National Institutes of Health, Biomedical Research Center, 251 Bayview Boulevard, Suite 100, Baltimore, MD 21224, USA.
authors.forename: Shaoming
authors.initials: S
authors.lastname: Song
authors.forename: Kotb
authors.initials: K
authors.lastname: Abdelmohsen
authors.forename: Yongqing
authors.initials: Y
authors.lastname: Zhang
authors.forename: Kevin G
authors.initials: KG
authors.lastname: Becker
authors.forename: Myriam
authors.initials: M
authors.lastname: Gorospe
authors.forename: Michel
authors.initials: M
authors.lastname: Bernier
mesh_terms: D000975:Antioxidants / Q000494:pharmacology*; D016207:Cytokines / Q000494:pharmacology*; D015536:Down-Regulation / Q000187:drug effects; D020869:Gene Expression Profiling; D056945:Hep G2 Cells; D006801:Humans; D015850:Interleukin-6 / Q000494:pharmacology*; D000076222:Mechanistic Target of Rapamycin Complex 1; D046912:Multiprotein Complexes; D016328:NF-kappa B / Q000037:antagonists & inhibitors*; D014176:Protein Biosynthesis / Q000187:drug effects; D011506:Proteins / Q000235:genetics / Q000378:metabolism*; D011759:Pyrrolidines / Q000494:pharmacology*; D034741:RNA, Small Interfering / Q000378:metabolism; D015398:Signal Transduction / Q000187:drug effects; D058570:TOR Serine-Threonine Kinases; D013859:Thiocarbamates / Q000494:pharmacology*; D014157:Transcription Factors / Q000378:metabolism*; D015533:Transcriptional Activation / Q000187:drug effects; D015854:Up-Regulation / Q000187:drug effects
chemical_list: D000975:Antioxidants; D016207:Cytokines; C469991:DDIT4 protein, human; D015850:Interleukin-6; D046912:Multiprotein Complexes; D016328:NF-kappa B; D011506:Proteins; D011759:Pyrrolidines; D034741:RNA, Small Interfering; D013859:Thiocarbamates; D014157:Transcription Factors; C020972:pyrrolidine dithiocarbamic acid; D000076222:Mechanistic Target of Rapamycin Complex 1; D058570:TOR Serine-Threonine Kinases