Abstract:
Objective To study the sources responsible for the generation of reactive oxygen species (ROS) induced by lo w doses of microcystin-LR(MCLR).
Methods Human embryonic kidney cells HEK293 stably expressing the organic anion transporting polypeptides 1B3 (HEK293-OATP1B3 cells) were treated with the solvent(0.1% dimethyl sulfoxide) and MCLR (10-50 nmol/L)for 4 or 24 h. The lactate dehydrogenase (LDH)release was measured and the levels of ROS were determined using fluorescent probes. The mRNA expressions of cytochrome P450 isoforms CYP1A1, 1A2 and 2E1 were determined by realtime polymerase chain reaction(PCR).
Results MCLR did not increase LDH release in HEK293-OATP1B3 cells at low concentrations (10-50nmol/L)when incubated for 4h. However, significant LDH releases were observed when the cells were incubated with MCLR at 20 nmol/L and higher concentrations for 24 h (P < 0.05). Exposure to MCLR (50 nmol/L)for 4 h significantly increased in tracellular ROS level (P < 0.01). MCLR did not affect the expression of CYP1A1. In contrast, the expression level of CYP2E1 mRNA was significantly upregulated in MCLR-treated cells (P < 0.01). The expression level of CYP1A2 was extremely low in both control and MCLR-treated cells.
Conclusion Low doses of MCLR induce the generation of ROS, and upregulate the expression of CYP2E1 mRNA, suggesting that CYP2E1 may be a potential source responsible for ROS generation by MCLR.
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