[The effects of soluble epoxide hydrolase inhibitors on cholesterol efflux in adipocytes].

OBJECTIVE: To observe the effects of soluble epoxide hydrolase inhibitors tAUCB on cholesterol efflux in adipocytes. METHODS: 3T3-L1 preadipocytes were induced to differentiation and maturation. Cells were stimulated with 100 µg/L LPS after starved for 24 hours, then tAUCB in various concentrations (1, 10, 50, 100 µmol/L)were added for 24 h, or incubated with the peroxisome proliferator activated receptor gamma (PPARγ) antagonist GW9662 (5 µmol/L). 0 µmol/L tAUCB treated group was taken as empty control. After then, the mRNA expression of PPARγ and adenosine triphosphate binding cassette transporter A1(ABCA1) in cells were determined via realtime-PCR, the amounts of protein expression of PPARγ and ABCA1 in cells were detected by Western blot, the efflux rates of (3)H-cholesterol in cells were detected by means of liquid scintillation counter. RESULTS: tAUCB could dose-dependently increase the apolipoprotein A1 (apoA1)-mediated cholesterol efflux in adipocytes. After stimulated by 1, 10, 50, 100 µmol/L tAUCB, cholesterol efflux rates were (5.93 ± 0.66)%, (7.40 ± 0.43)%, (8.30 ± 0.34)%, (9.77 ± 0.42)% respectively, there were significant difference after treated by 10 - 100 µmol/L tAUCB compared with control (5.67 ± 0.17)% (P < 0.05).With the concentration of tAUCB increased, ABCA1, PPARγ mRNA and protein expression were also dose-dependently up-regulated. GW9662 could significantly inhibit the effects of tAUCB, and then reduce the cholesterol efflux and the expression of PPARγ and ABCA1 in adipocytes. CONCLUSIONS: tAUCB could up-regulate PPARγ expression in adipocytes, and promote the cholesterol efflux of adipocytes via apoA1-ABCA1 pathway, which might decrease the cellular cholesterol accumulation in adipocytes.

Activation of Cdc2 contributes to apoptosis in HPV E6 expressing human keratinocytes in response to therapeutic agents.

Infection with human papillomaviruses (HPV) is strongly associated with the development of cervical cancer. The HPV E6 oncogene induces apoptosis in cervical cancer precursor lesions but the mechanism is poorly understood. While it is expected that inactivation of p53 by E6 should lead to a reduction in apoptosis, E6 also sensitizes cells to apoptosis under some experimental conditions. Here, we demonstrate that expression of E6 in human keratinocytes rendered sensitization to chemotherapeutic agents. The cell death was shown to be by apoptosis involving caspase activation and the mitochondria pathway. To explore mechanisms involved in sensitization of E6 expressing cells to apoptosis, we used a proteomic approach to identify proteins differentially expressed in E6 expressing and control keratinocytes. Among nearly a thousand proteins examined, Cdc2 was demonstrated to be the most dramatically up-regulated protein in E6 expressing cells. p53 degradation appears to be important for the up-regulation of Cdc2 by E6. Using genetic, pharmacologic, and siRNA strategies, a role for Cdc2 in E6 expression-conferred apoptosis was demonstrated. Thus, these results have important therapeutic implications in enhancing the efficacy of chemotherapy.