TRAIL-induced apoptosis of FHIT-negative lung cancer cells is inhibited by FHIT re-expression

FHIT overexpression in HepG2 hepatoma cells affects growth and cyclin D1 expression in vitro

The aim of this study was to investigate the methylation status of fragile histidine triad (FHIT) and the effects of FHIT on cell growth and cyclin D1 expression in hepatoma cells. The total proteins from the human hepatoma cell lines HepG2, Hep3B and Huh7 were collected and the expression levels of FHIT were analyzed. The methylation status in the promoter region of FHIT in the hepatoma cells was measured using methylation-specific polymerase chain reaction (PCR). The HepG2, Hep3B and Huh7 cells were subsequently treated with 5-aza-2′-deoxycytidine (5-azadc) and the restoration of FHIT expression was then examined. A p-hemagglutinin (HA)-FHIT plasmid was constructed and used to transfect the HepG2 cells, and the inhibitory effects of the transfection on cell growth were then assessed. In addition, HepG2 cells were cotransfected with the pHA-FHIT plasmid and a cyclin D1 luciferase reporter plasmid, and the effects of FHIT on the activity of cyclin D1 transcription factor were analyzed using a luciferase assay. FHIT was observed to be expressed at a low level in Hep3B and HepG2 cells; however, it was expressed at a relatively high level in Huh7 cells. The promoter region of FHIT in the Hep3B and HepG2 cells was partially methylated, and 5-azadc treatment induced an increased expression of FHIT. The increased expression of FHIT inhibited the growth of HepG2 cells. Cotransfection with the pHA-FHIT plasmid significantly inhibited the transcriptional activity of the cyclin D1 promoter and decreased the expression of cyclin D1 in HepG2 cells. In conclusion, FHIT was partially methylated in the HepG2 and Hep3B hepatoma cells. The overexpression of FHIT inhibited cell growth and decreased the expression of cyclin D1 in HepG2 cells.

Allicin induces anti-human liver cancer cells through the p53 gene modulating apoptosis and autophagy

Hepatocellular carcinoma (HCC) is the most prevalent type of liver cancer globally and ranks first among the cancer-related mortalities in Taiwan. This study aims to understand the modes of cell death mechanism induced by allicin, a major phytochemical of crushed garlic, in human hepatoma cells. Our earlier study indicated that allicin induced autophagic cell death in human HCC Hep G2 (p53(wild type)) cells, whereas in the present study, allicin induced apoptotic cell death through caspase-dependent and caspase-independent pathways by reactive oxygen species (ROS) overproduction in human HCC Hep 3B (p53(mutation)) cells. To gain insight into the cell death mechanism in p53 knocked down Hep G2, we silenced the p53 gene using siRNA-mediated silencing. Allicin treatment induced apoptotic cell death in p53 knocked down Hep G2 cells similar to that of Hep 3B cells. These results suggest that allicin induced cell death in human hepatoma cells through either autophagy or apoptosis and might be a potential novel complementary gene therapeutic agent for the treatment of apoptosis-resistant cancer cells.