PT  - JOURNAL ARTICLE
AU  - M. Isabel Guillén
AU  - M. Teresa Donato
AU  - Ramiro Jover
AU  - JoséV. Castell
AU  - R. Fabra
AU  - R. Trullenque
AU  - M. José Gómez-Lechón
TI  - Oncostatin M Down-regulates Basal and Induced Cytochromes P450 in Human Hepatocytes
DP  - 1998 Apr 01
TA  - Journal of Pharmacology and Experimental Therapeutics
PG  - 127--134
VI  - 285
IP  - 1
4099  - http://jpet.aspetjournals.org/content/285/1/127.short
4100  - http://jpet.aspetjournals.org/content/285/1/127.full
SO  - J Pharmacol Exp Ther1998 Apr 01; 285
AB  - The effects of oncostatin M on the expression of different cytochrome P450 (CYP) isozymes has been investigated in human hepatocytes. The dose-response and time-course analyses of effects on CYP1A2 and CYP3A4 isozymes revealed that maximal inhibition was reached after 48 hr of exposure of human hepatocytes to 25 units/ml oncostatin M. Reductions in CYP1A2 and CYP3A4 activity produced by oncostatin M correlated with decreases in protein content, de novo protein synthesis and specific mRNA levels, thus suggesting that oncostatin M could down-regulate CYP expression at the transcriptional level. The inhibitory potency of oncostatin M on CYP expression was compared with that of other cytokines belonging to the interleukin-6 receptor family (interleukin-6, interleukin-11 and leukemia inhibitory factor), and interferon-γ, which is recognized to inhibit human CYP expression, and granulocyte colony-stimulating factor, a cytokine that shares structural homology with the interleukin-6 family but has a different transduction signal. Maximal reductions in CYP1A2 activity were reached after 48 hr of treatment with cytokines. At that time, oncostatin M showed the highest inhibitory effects on CYP1A2 activity (38% of control), followed by interferon (49% of control) and interleukin-6 (60% of control), whereas minor effects were produced by the other cytokines (74–80%). Comparable decreases were observed for CYP2A6, CYP2B6 and CYP3A4 activities. Enzymatic activity and de novoprotein synthesis of 3-methylcholanthrene-induced CYP1A2 and dexamethasone-induced CYP3A4 were also reduced to a much greater extent by oncostatin M than by other cytokines. The results show that oncostatin M is the most effective cytokine in down-regulating CYP isozymes in human hepatocytes, and its effects were evident even after removal of the cytokine from the culture medium. The American Society for Pharmacology and Experimental Therapeutics