Clement G Yedjou1, Paul B Tchounwou1. 1. Cellomics and Toxicogenomics Research Laboratory, NIH-Center for Environmental Health, College of Science, Engineering and Technology, Jackson State University, 1400 Lynch Street, P.O. Box 18540, Jackson, Mississippi, USA.
Abstract
BACKGROUND: Recent studies in our laboratory have demonstrated that lead is cytotoxic to human liver carcinoma (HepG2) cells, showing a 48 h-LD50 of 35.5 ± 9.2ug/mL. However, its molecular mechanisms of toxicity are still largely unknown. Hence, the aim of the present study was to use HepG2 cells as a test model to investigate the molecular mechanisms of lead-induced oxidative stress and modulation of cellular response proteins. METHODS: To achieve this goal, we performed lipid peroxidation assay for malondialdehyde (MDA) determination, western blot and densitometric analyses for genes and related proteins expression in human liver carcinoma cells. RESULTS: Data obtained from the lipid peroxidation assay demonstrated a significant increase (p ≤ 0.05) of MDA levels in lead-treated HepG2 cells compared to control cells. Western Blot analysis showed a strong dose-response relationship with regard to p53 expression, and a significant repression in cyclin A in lead-treated cells. CONCLUSIONS: Findings from this research indicate that lead is able to cause oxidative stress, cell cycle arrest through activation of the 53-kDa tumor suppressor protein and down regulation of the cyclin A protein in human liver carcinoma (HepG2) cells.
BACKGROUND: Recent studies in our laboratory have demonstrated that lead is cytotoxic to human liver carcinoma (HepG2) cells, showing a 48 h-LD50 of 35.5 ± 9.2ug/mL. However, its molecular mechanisms of toxicity are still largely unknown. Hence, the aim of the present study was to use HepG2 cells as a test model to investigate the molecular mechanisms of lead-induced oxidative stress and modulation of cellular response proteins. METHODS: To achieve this goal, we performed lipid peroxidation assay for malondialdehyde (MDA) determination, western blot and densitometric analyses for genes and related proteins expression in human liver carcinoma cells. RESULTS: Data obtained from the lipid peroxidation assay demonstrated a significant increase (p ≤ 0.05) of MDA levels in lead-treated HepG2 cells compared to control cells. Western Blot analysis showed a strong dose-response relationship with regard to p53 expression, and a significant repression in cyclin A in lead-treated cells. CONCLUSIONS: Findings from this research indicate that lead is able to cause oxidative stress, cell cycle arrest through activation of the 53-kDa tumor suppressor protein and down regulation of the cyclin A protein in human liver carcinoma (HepG2) cells.
Authors: Clement G Yedjou; Jessica N Milner; Carolyn B Howard; Paul B Tchounwou Journal: Int J Environ Res Public Health Date: 2010-04-28 Impact factor: 3.390