High Glucose Concentration Alters Cell Proliferation Dynamics in Human Hepatoma Cells

The aim of this study was to develop an in vitro model to in-vestigate the molecular mechanisms of glucose-induced inhibition of cell proliferation. HuH7 cells were grown in the presence or ab-sence of glucose for 7 days and cell proliferation was stimulated by exposure to thioacetamide. Lactate dehydrogenase leakage and 3H-thymidine incorporation were used as indices of toxicity and DNA synthesis, respectively. Cell cycle progression and protoonco-gene expression was monitored by ow cytometry and slot-blot analyses. Toxicity caused by thioacetamide regressed with time in the presence of 11 mM glucose (control). However, in the pres-ence of 28 mM glucose, sustained toxicity was evident as mirrored by lactate dehydrogenase leakage. Peak DNA synthesis noted at 48 hours in the thioacetamide-treated group (11 mM glucose) was signi cantly diminished in the presence of 28 mM glucose. In-creased c-myc expression was observed as early as 30 minutes in the thioacetamide-treated group. When cells were exposed to 28 mM glucose, c-myc expressionwasdelayed and diminished.Methylation pro le studies revealed no appreciable changes, but c-myc was sig-ni cantly ampli ed in the control, thioacetamide-, and in the pres-ence of 28 mM of glucose-treated groups which correlated with mRNA changes in these groups. In the glucose-pretreated group (28 mM) signi cant ampli cation of the c-myc gene was observed at later time points but there was no change in the mRNA expres-sion, indicating that the expression was delayed. This study shows that high glucose concentrations diminish DNA synthesis and cell cycle progression normally stimulated by thioacetamide. It is con-cluded that high glucose concentration causes cell cycle arrest vi