Effects of Mangiferin on Glucose and Lipid Metabolism of Insulin-resistant HepG2 Cells / 中国药房

OBJECTIVE：To analyze the effects of mangiferin （MGF）on glucose and lipid metabolism in insulin resistance （IR）HepG2 cells，and to explore the potential mechanism. METHODS ：Using human hepatoma HepG 2 cells as research objects ， 1 mmol/L palmitic acid and 2 mmol/L oleic acid were used to establish the IR-HepG 2 cell model. Using metformin hydrochloride as positive control ，the effects of low-concentration ，medium-concentration and high-concentration MGF （125，250，500 μmol/L）on the corrected glucose consumption ，the contents of triglyceride （TG）and total cholesterol （TC）in IR-HepG 2 cells were detected. The mRNA expression of APN ，AdipoR2，APPL1，AMPK in the upstream of AMPK signaling pathway and IRS- 1，Akt and GLUT4 in the downstream insulin signaling pathway were detected by RT-PCR. The phosphorylation level of AMPK protein was detected by Western blot assay. RESULTS ：Compared with control group ，corrected glucose consumption ，mRNA expression of APN，AdipoR2，APPL1，AMPK，IRS-1 and GLUT 4，as well as the phosphorylation level of AMPK protein were decreased significantly in model group ，while the contents of TG and TC were increased significantly （P＜0.05 or P＜0.01）. Compared with model group ， corrected glucose consumption ， mRNA expression of APN （except for MGF medium-concentration and high-concentration groups ），AdipoR2，APPL1，AMPK（except for MGF medium-concentration and high-concentration groups ）， IRS-1（except for MGF medium-concentration and high-concentration groups ），Akt（except for positive control group ），GLUT4 （except for MGF high-concentration group ）were increased significantly in administration groups ，while the contents of TG and TC were decreased significantly （P＜0.05 or P＜0.01）. CONCLUSIONS ：Mangiferin may activate APN ，which is the upstream target of pathway ，and then regulate AMPK signaling pathway ，so as to promote glucose uptake of IR-HepG 2 cells，reduce TG and TC contents，and improve IR and abnormal glucose and lipid metabolism.

Development And Application Of Tests With Human Derived Cells For The Detection Of Environmental Genotoxins.

Two novel approaches are described, in which metabolically competent human derived cells were used for the detection of genotoxic effects of environmental carcinogens. In the first, human hepatoma (Hep G2) cells were used for micronucleus and single cells were used for micronucleus and single cell gel electrophoresis (SCGE) assays. These cells have retained the activities of phase I and phase II enzymes which are usually lost during cultivation. We demonstrated that these cells are suitable for the detection of the genotoxic effects of representatives of various classes of DNA-reactive procarcinogens such as benzo(a) pyrene (B(a)P), 2-amino-3-methylimidazo-[4,5-f]-quinoline (IQ), cyclophosphamide (CP), and N-nitrosodimethylamine (NDMA), isatidine and aflatoxin B1 (AFB1). Furthermore, we found that these tests also detect the mutagenic effects of rodent carcinogens such as safrole and hexamethylphosphoramide (HEMPA), which give negative results in conventional in vitro procedures. Additional experimental series showed that genotoxicity assays with Hep G2 cells are also useful for the detection of co- and antimutagens, in particular for compounds which act via induction of activating and detoxifying enzymes. In the second approach, a protocol for stable co-cultivation sandwich cultures with primary human hepatocytes was used. The cultivation of the cells under organotypical conditions leads to an extension of their life span and results in an improved expression of drug metabolising enzymes. Two different experimental models were developed: In the first, the induction of HPRT mutations in V-79 cells was used as an endpoint, in the seconds, single strand breaks were measured in human K562 cells in SCGE assays. Experiments which were carried out with B(a)P and 7,12-diemethylbenz(a)anthracene as model compounds indicate that in both systems positive results are obtained. In conclusion, our data show that tests with human Hep G2 cells as well as sandwich cultures with primary human liver cells are useful for the detection of environmental carcinogens and probably reflect their effects in humans better than conventional in vitro assays with metabolically incompetent cells which are currently used in most mutagenicity studies.