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| Author(s): |
Maria Alice Vieira Willrich
Total Authors: 1
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| Document type: | Doctoral Thesis |
| Press: | São Paulo. |
| Institution: | Universidade de São Paulo (USP). Conjunto das Químicas (IQ e FCF) (CQ/DBDCQ) |
| Defense date: | 2011-10-07 |
| Examining board members: |
Rosario Dominguez Crespo Hirata;
Marcelo Chiara Bertolami;
Silvya Stuchi Maria Engler;
Elida Paula Benquique Ojopi;
Elvira Maria Guerra Shinohara
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| Advisor: | Rosario Dominguez Crespo Hirata |
| Abstract | |
Background: CYP3A4 and CYP3A5 are enzymes from the cytochrome P450 resposible for the biotransformation of endogenous steroids and several drugs, e.g. statins. Polymorphisms in CYP3A4 and CYP3A5 (CYP3A4*1B, CYP3A5*3C and CYP3A5*1D) have been associated with variation of lipid-lowering response in individuals treated with atorvastatin and simvastatin. In this study we evaluated the effect of hypolipemiants on expression and activity of CYP3A4 and CYP3A5, in HepG2 and Caco-2 cell lines as well as peripheral blood mononuclear cells (PBMC) in hypercholesterolemic individuals, and their relationship with CYP3A4 and CYP3A5 variants. Methods: We analyzed 99 normolipidemic individuals (NL) and 139 hypercholesterolemic (HC). HC subjects were treated with atorvastatin (HC, 10 mg/day/4 weeks). Analysis of CYP3A4*1B, CYP3A5*3C e CYP3A5*1D variants was performed with PCR-RFLP or sequencing assays and mRNA expression of CYP3A4 and CYP3A5 with Quantitative Real-time PCR (qRT-PCR) was performed . Total protein content was extracted from HepG2 for Western Blotting experiments. Activity of CYP3A4 and CYP3A5 in vivo was evaluated by 6βOH-cortisol and cortisol ratio in urine samples, by HPLC-UV method. Results: Baseline mRNA expression is different for HepG2 and Caco-2. Caco-2 expresses 31 times more CYP3A4 and 122 times more CYP3A5 than HepG2. In HepG2 cells treated for 12h, atorvastatin 20 µM increased CYP3A4 expression in 10 times, when compared to the control (p=0.006). After 24h treatment, atorvastatin (1-20 µM) increased CYP3A4 mRNA expression in 5 to 8 times, in HepG2 (p< 0.001). To CYP3A5, exposure for 12h to atorvastatin 20 µM increased expression in 4 times when compared to the control (p<0.001). Exposure to simvastatin 1.0 µM for 24 h increased CYP3A4 expression in 2 times, (p<0.01), in HepG2. With the 24h treatment,simvastatin (0.1 µM - 10 µM) CYP3A5 showed increased mRNA expression in 2 to 4 times (p<0.05). HepG2 cell line carries homozygous functional alleles (CYP3A4*1A e CYP3A5*1A). Caco-2 carries heterozygous CYP3A5*3C and CYP3A5*1D. We evaluated the protein expression of CYP3A4 and CYP3A5 with Western Blotting in HepG2 cells, after atorvastatin (0.1 - 20 µM) and simvastatin (0.01 - 10 µM) for 12 and 24 h. The proteins profile did not change with statins treatment. In PBMC, baseline mRNA expression of CYP3A4 is approximately 2.6 to 9.5 times higher than CYP3A5 (p< 0.05). There was a correlation in expression between CYP3A4 and CYP3A5, before (r2 = 0.22; p< 0.0001) and after treatment (r2 = 0.58; p<0.0001) with atorvastatin. Baseline mRNA expression of CYP3A4 and CYP3A5 is higher in (NL) than in (HC) (p<0.05). Atorvastatin treatment did not increase CYP3A4 and CYP3A5 mRNA in PBMC (p>0.05). CYP3A4/5 activity was higher in NL subjects than in HC (p<0.0001). Atorvastatin treatment did not affect CYP3A4/5 activity in HC (p>0.05). The studied variants CYP3A4*1B, CYP3A5*3C e CYP3A5*1D analyzed as a haplotype block did not affect response to treatment, mRNA expression or activity of CYP3A4 and CYP3A5. However, AGT haplotype showed lower CYP3A5 mRNA expression levels when compared to GAC and GAT haplotypes at baseline (p<0.05). Conclusion: The results of this study allow us to conclude that atorvastatin and simvastatin, but not ezetimibe, influence the expression of CYP3A4 and CYP3A5 mRNA in vitro in HepG2 cell line, but this effect was not reproduced in Caco-2 cell line or PBMC. CYP3A4 and CYP3A5 present great interindividual variability, despite the individual´s haplotype and is not influenced by atorvastatin. (AU) | |
| FAPESP's process: | 07/02944-5 - Hypolipemiant effects on CYP3A4 and CYP3A5 mRNA expression in vitro and in vivo |
| Grantee: | Maria Alice Vieira Willrich |
| Support Opportunities: | Scholarships in Brazil - Doctorate |