RNA interference-mediated silencing of cytochrome P450 3A4 gene in CHL-3A4 cells / 南方医科大学学报

<p><b>OBJECTIVE</b>To investigate the effect of small hairpin interfering RNA (shRNA) in suppressing cytochrome P450 3A4 (CYP3A4) gene expression in CHL-3A4 cells.</p><p><b>METHODS</b>Three shRNA expression vectors targeting CYP3A4 gene (CYP3A4 I, C YP3A4 II, and CYP3A4 III, respectively) were designed, synthesized and transfected into CHL-3A4 cells via liposomes. The inhibitory effect of shRNA on CYP 3A4 gene expression was detected by Western blotting and RT-PCR, and the effect of shRNA transfection in suppressing cyclophosphamide-induced cytotoxicity was measured using MTT assay.</p><p><b>RESULTS</b>The vector carrying CYP3A4 III shRNA significantly reduced the expression of CYP3A4 gene at both the mRNA (75%) and protein levels (80%) in CHL3A4 cells. The cytotoxicity of cyclophosphamide was markedly inhibited by CYP3A4 III-mediated suppression of CYP3A4 gene expression by 75% in CHL-3A4 cells.</p><p><b>CONCLUSION</b>The vector-mediated RNA interference can suppress CYP3A4 gene expression in CHL-3A4 cells, and RNA interference technique provides a new means for studying cytochrome P450 gene function in mammalian cells.</p>

Effect of ketoconazole on the activity of CYP4503A4 and CYP450 1A2 of hepatic microsomes in healthy adults / 南方医科大学学报

<p><b>OBJECTIVE</b>To observe the effect of ketoconazole on the activity of cytochrome P450 (CYP) 1A2 and 3A4 in hepatic microsomes of healthy adults.</p><p><b>METHODS</b>Human hepatic microsomes obtained from healthy adults were randomly divided into control group and ketoconazole-treatment groups at different concentrations. After 15 min of culture, the substrates (testosterone for CYP3A4 and phenacetin for CYP1A2) were added and incubated for another 20 min. The metabolites (6-testosterone and acetaminophen) were then measured with high-performance liquid chromatography (HPLC) to assess the activities of CYP3A4 and 1A2.</p><p><b>RESULTS</b>Significant difference was found between the groups in the quantity of 6-testosterone and the relative activity of CYP3A4 (P<0.05). The IC(50) of ketoconazole for CYP3A4 was 0. 16 mg/L. Both the quantity of 6-testosterone and the relative activity of CYP3A4 were reduced gradually with the increment of ketoconazole concentration. Significant differences were found between the ketoconazole groups and the control group in both the quantity of acetaminophen and the relative activity of CYP1A2 (P<0.05). Ketoconazole at low doses reduced CYP1A2 activity and but increased the activities at high doses (P<0.05).</p><p><b>CONCLUSION</b>In the range of maximum clinical blood concentration, ketoconazole can inhibit the activity of CYP3A4, but not that of CYP1A2, in the hepatic microsomes in healthy adults.</p>

Cardiac hypertrophy induced by prostaglandin F(2alpha) may be mediated by calcineurin signal transduction pathway in rats / 生理学报

In this paper, we studied the relationship between the prostaglandin F(2alpha) (PGF(2alpha))-induced cardiac hypertrophy and calcineurin (CaN) signal transduction pathway in vivo and in vitro. Male Sprague-Dawley rats were given a single i.p. injection with monocrotaline (MCT) (60 mg/kg) and then given orally with celecoxib (20 mg/kg) or vehicle once a day for 14 d before (from d 1 to d 14) or after (from d 15 to d 28) right ventricular hypertrophy (RVH) was formed. Body weight (BW), right ventricular weight (RV), left ventricular with septum weight (LV), as well as lung weight were determined. RVH index (RVHI=RV/LV), RV/BW, and lung weight/BW were calculated and histological changes were observed with transmission electron microscope. PGF(2alpha) level, atrial natriuretic peptide (ANP) and CaN mRNA expressions, expression of CaN and its downstream effectors, NFAT(3) and GATA(4) protein were assayed by EIA kit, RT-PCR, and Western blotting, respectively. The cardiomyocyte hypertrophy in primary culture induced by PGF(2alpha) (0.1 micromol/L) was evaluated by measuring the cell diameter, protein content, and ANP mRNA as well as CaN mRNA expressions. It was found that 14 d or 28 d after MCT was given, the RVHI, RV/BW, and lung weight/BW were significantly increased by 47%, 53% and 118%, and by 64%, 94% and 156%, respectively; at the same time PGF(2alpha) levels in RV tissue were increased by 44% and by 51% with increasing RVHI, and elevated expressions of ANP and CaN mRNA, as well as CaN, NFAT(3) and GATA(4) proteins in a positive correlation manner. Furthermore, some histological injuries were found in RV tissue. Celecoxib, a cyclooxygenase inhibitor, obviously blunted the elevation of RVHI, RV/BW, and lung weight/BW no matter it was given before or after RVH. In vitro experiments showed that 0.1 micromol/L PGF(2alpha) significantly increased the cardiomyocyte diameter and protein content, and promoted ANP and CaN mRNA expressions, which was blocked by cyclosporin A, a CaN inhibitor. Our results indicate that PGF(2alpha) may be involved in cardiac hypertrophy induced by MCT in rats through CaN signal transduction pathway.