title: Modulation of CYP3A4 expression by ceramide in human colon carcinoma HT-29 cells.
abstract: Cytochrome P450 3A4 (CYP3A4) enzyme is responsible for the metabolic activation and inactivation of the majority of clinically used drugs in human liver and intestines. Recent studies have increasingly implicated various inflammatory stimuli to cause changes in the activities and expression levels of CYPs. However, the underlying mechanisms are largely unknown. In the present study, our studies investigated the effects of ceramide on CYP3A4 expression in human colon carcinoma HT-29 cells. Treatment with the cell-permeable ceramide analog C(6)-ceramide to the cells significantly decreased the expression of CYP3A4. By contrast, C(6)-dihydroceramide, a biologically inactive analog of C(6)-ceramide, did not affect CYP3A4 expression. We found that bacterial sphingomyelinase (SMase) and tumor necrosis factor-alpha (TNF), which are known to increase intracellular ceramide levels, also markedly suppressed the synthesis of CYP3A4. To elucidate whether nitric oxide (NO) participates in suppression of CYP3A4 expression by ceramide, the effects of NO modulators were determined. Treatment with N(G)-monomethyl-L-arginine, a competitive inhibitor of inducible nitric oxide synthase (iNOS), was able to protect ceramide-dependent CYP3A4 suppression. In contrast, the addition of S-nitroso-N-acetylpenicillamine, a NO donor, to HT-29 cells reduced CYP3A4 expression. The addition of iNOS antisense oligonucleotide prevented ceramide-mediated induction of iNOS expression and restored CYP3A4 expression. Wortmannin which is known to inhibit phosphatidylinositol 3-kinase (PI3-K) blocked CYP3A4 suppression by ceramide. Taken together, our results demonstrate that ceramide-mediated suppression of CYP3A4 is due to production of NO, which might result from activation of PI3-K.
authors.affiliation: College of Pharmacy, Chung-Ang University, 221 Huksuk-dong, Dongjak-gu, Seoul, Republic of Korea. yjchun@cau.ac.kr
authors.forename: Young-Jin
authors.initials: YJ
authors.lastname: Chun
authors.forename: Sunghee
authors.initials: S
authors.lastname: Lee
authors.forename: Soon Ae
authors.initials: SA
authors.lastname: Yang
authors.forename: Sungsik
authors.initials: S
authors.lastname: Park
authors.forename: Mie Young
authors.initials: MY
authors.lastname: Kim
mesh_terms: D000730:Androstadienes / Q000494:pharmacology; D002518:Ceramides / Q000494:pharmacology*; D003110:Colonic Neoplasms / Q000201:enzymology / Q000235:genetics; D051544:Cytochrome P-450 CYP3A; D003577:Cytochrome P-450 Enzyme System / Q000096:biosynthesis / Q000235:genetics*; D004791:Enzyme Inhibitors / Q000494:pharmacology; D015870:Gene Expression / Q000187:drug effects; D006801:Humans; D009569:Nitric Oxide / Q000096:biosynthesis; D020030:Nitric Oxide Donors / Q000494:pharmacology; D019001:Nitric Oxide Synthase / Q000037:antagonists & inhibitors / Q000096:biosynthesis; D052247:Nitric Oxide Synthase Type II; D020319:Oligodeoxyribonucleotides, Antisense / Q000494:pharmacology; D000081082:Phosphoinositide-3 Kinase Inhibitors; D026423:S-Nitroso-N-Acetylpenicillamine / Q000494:pharmacology; D013108:Sphingomyelin Phosphodiesterase / Q000494:pharmacology; D014407:Tumor Cells, Cultured; D014409:Tumor Necrosis Factor-alpha / Q000494:pharmacology; D000077191:Wortmannin; D019323:omega-N-Methylarginine / Q000494:pharmacology
chemical_list: D000730:Androstadienes; D002518:Ceramides; D004791:Enzyme Inhibitors; D020030:Nitric Oxide Donors; D020319:Oligodeoxyribonucleotides, Antisense; D000081082:Phosphoinositide-3 Kinase Inhibitors; D014409:Tumor Necrosis Factor-alpha; C101954:N-caproylsphingosine; D019323:omega-N-Methylarginine; D009569:Nitric Oxide; D026423:S-Nitroso-N-Acetylpenicillamine; D003577:Cytochrome P-450 Enzyme System; C496319:NOS2 protein, human; D019001:Nitric Oxide Synthase; D052247:Nitric Oxide Synthase Type II; C104464:CYP3A protein, human; D051544:Cytochrome P-450 CYP3A; C510163:CYP3A4 protein, human; D013108:Sphingomyelin Phosphodiesterase; D000077191:Wortmannin