title: The role of MAPK in the biphasic dose-response phenomenon induced by cadmium and mercury in HEK293 cells.
abstract: Some studies show that Cd(2+) and Hg(2+) may induce cell proliferation and apoptosis via biphasic dose-response relationship in human cells. However, mechanisms underlying this phenomenon are still in puzzle. In this study, we aim at detecting the biphasic effects of Cd(2+) and Hg(2+) on proliferation and apoptosis of human embryonic kidney 293 (HEK293) cells, analyzing the change of the mitogen-activated protein kinase (MAPK) pathways, and discussing the relationship between them. The results demonstrate that Cd(2+) and Hg(2+) can stimulate cell proliferation at lower concentrations (0.05 and 0.5 microM) but inhibit it at higher concentrations (50 and 500 microM). Apoptosis increases at higher concentrations (50 and 500 microM) of Cd(2+) and Hg(2+). While 0.5 microM Cd(2+) and Hg(2+) decrease the JNK phosphorylation, 50 microM Cd(2+) and Hg(2+) increase the JNK and P38 phosphorylation. When HEK293 cells are treated with 20 microM JNK inhibitor or 100 microM ERK1/2 inhibitor, the cell proliferation do not increase significantly at low concentrations (0.05 and 0.5 microM), but still decrease at high concentrations (50 and 500 microM). When HEK293 cells are treated with 20 microM P38 inhibitor, the tendency of cell proliferation is not affected. Data in our study suggests that activation of MAPK pathway may be involved in the biphasic effect induced by Cd(2+) and Hg(2+).
authors.affiliation: Department of Toxicology, School of Public Health, Peking University, Beijing 100083, PR China.
authors.forename: Changfu
authors.initials: C
authors.lastname: Hao
authors.forename: Weidong
authors.initials: W
authors.lastname: Hao
authors.forename: Xuetao
authors.initials: X
authors.lastname: Wei
authors.forename: Lina
authors.initials: L
authors.lastname: Xing
authors.forename: Jianjun
authors.initials: J
authors.lastname: Jiang
authors.forename: Lanqin
authors.initials: L
authors.lastname: Shang