Human Cancer HepG2 Research Articles

Essential oil of Curcuma wenyujin induces apoptosis in human hepatoma cells

To investigate the effects of the essential oil of Curcuma wenyujin (CWO) on growth inhibition and on the induction of apoptosis in human HepG2 cancer cells. The cytotoxic effect of drugs on HepG2 cells was measured by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetra-zolium bromide (MTT) assay. DNA fragmentation was visualized by agarose gel electrophoresis. Cell cycle and mitochondrial transmembrane potential (Delta psi m) were determined by flow cytometry (FCM). Cytochrome C immunostaining was evaluated by fluorescence microscopy. Caspase-3 enzymatic activity was assayed by the cleavage of Ac-DEVD-R110. Cleaved PARP and active caspase-3 protein levels were measured by FCM using BD(TM) CBA Human Apoptosis Kit. Treatment with CWO inhibited the growth of HepG2 cells in a dose-dependent manner, and the IC50 of CWO was approximately 70 mug/mL. CWO was found to inhibit the growth of HepG2 cells by inducing a cell cycle arrest at S/G(2). DNA fragmentation was evidently observed at 70 mug/mL after 72 h of treatment. During the process, cytosolic HepG2 cytochrome C staining showed a markedly stronger green fluorescence than in control cells in a dose-dependent fashion, and CWO also caused mitochondrial transmembrane depolarization. Furthermore, the results clearly demonstrated that both, activity of caspase-3 enzyme and protein levels of cleaved PARP, significantly increased in a dose-dependent manner after treatment with CWO. CWO exhibits an antiproliferative effect in HepG2 cells by inducing apoptosis. This growth inhibition is associated with cell cycle arrest, cytochrome C translocation, caspase 3 activation, Poly-ADP-ribose polymerase (PARP) degradation, and loss of mitochondrial membrane potential. This process involves a mitochondria-caspase dependent apoptosis pathway. As apoptosis is an important anti-cancer therapeutic target, these results suggest a potential of CWO as a chemotherapeutic agent.

Effect of Frying-Meat Emission Particulate On 17β-Estradiol 2- and 4-Hydroxylation in Human Lung Adenocarcinoma Cl5 Cells

The effect of airborne frying-meat emission particulate (FMEP) on metabolism of 17 g -estradiol (E 2 ) to potentially toxic catechol estrogens 2- and 4-hydroxyestradiol (2- and 4-OH-E 2 ) was determined using human lung adenocarcinoma CL5 cells treated with organic extracts of beef FMEP. E 2 was incubated with microsomes prepared from untreated CL5 cells or cells treated with 200 w g/ml FMEP extract for 6 h. E 2 metabolites formed were analyzed by high-performance liquid chromatography (HPLC). The results revealed that treatment with FMEP produced three-and twofold increases of 2- and 4-hydroxylation of E 2 , respectively. Monooxygenase activity and immunoblot analyses showed that FMEP markedly induced microsomal 7-ethoxyresorufin O-deethylase (EROD) activity and cytochrome P-450 (CYP) IAI and CYPIBI protein levels. Similar increases in E 2 hydroxylation, EROD activity, and CYP protein levels were observed with HepG2 human hepatoma and MCF-7 human breast cancer cells treated with FMEP or 1 w M dibenz[a,h]anthracene. Cotreatment of CL5 cells with FMEP extract and 2 w M f -naphthoflavone, an arylhydrocarbon receptor antagonist, blocked the inductive effects of FMEP on E 2 hydroxylation and EROD activity. Additions of 0.01, 0.1, or 1 w M f -naphthoflavone, a CYP inhibitor, to microsomes produced concentration-dependent decreases in E 2 2-hydroxylation and EROD activity of CL5 cells induced by dibenz[a,h]anthracene. The present finding demonstrates that FMEP can increase formation of 2-OH-E 2 and 4-OH-E 2 by human lung cells, and induction of CYP1A1 and CYP1B1 is a potential mechanism underlying increased E 2 metabolism. The toxicological significance of FMEP and estrogen interaction warrants further investigation.