Methyl triclosan
(mTCS) is a methylated derivative of triclosan
(TCS), which is extensively used as an antimicrobial component of
various nursing products and disinfectants. Current research studies
of mTCS mainly focused on the environmental persistence and bioaccumulation
potential. Knowledge regarding the toxicity and carcinogenicity of
mTCS is limited until now. In this study, the human hepatocyte L02
cells were used to investigate the cellular effects of mTCS under
different concentrations (0.1–60 μM). The hormesis effect
was observed where a low dose of mTCS (≤5 μM) exposure
stimulated the cell proliferation ability, while high-dose exposure
(≥20 μM) inhibited cell proliferation. In the same time,
low doses of mTCS (0.5 and 1 μM) induced enhanced anchorage-independent
proliferation ability and cell migration ability, indicating a positive
effect on malignant transformation in L02 cells. Moreover, reactive
oxygen species productions were significantly increased after mTCS
exposure (≥1 μM), as compared with the control group.
Furthermore, expressions of tumor-related genes, mouse double minute
2 (MDM2), matrix metalloproteinase 9 (MMP9), and proliferating cell
nuclear antigen (PCNA), and proto-oncogene MYC (c-Myc), Jun, and FosB were
significantly upregulated, while no significant changes were observed
on expressions of apoptosis-related and cell cycle-related genes in
L02 cells after exposure of low-dose mTCS. In conclusion, these results
indicated that a low dose of mTCS had a hormesis effect in L02 cells
on cell proliferation and malignant transformation in vitro, which might be mediated through oxidative stress response.