Effect of Curcumin on HSP Expression in Tilapia Hepatocytes under Hydrogen Peroxide Stress

  Objective  Expression of heat shock protein (HSP) gene under oxidative stress in the presence of curcumin was studied to understand the toxicological function of the protein and the pharmacological mechanism of curcumin in hepatocytes of Oreochromis nilotica.

  Methods   Tilapia hepatocytes and those pretreated with curcumin for 24 h were subjected to H₂O₂ stress for 0, 1, or 2.5 h. The expressions of HSP70, HSP90α, HSP90β, HSP60, and HSP75, as well as 5 small molecule HSP genes, i.e., HSP30, HSPB1, HSPB7, HSPB8, and HSPB11, in the cells were determined by qPCR.

  Results  The H₂O₂ treatment for 1 h significantly increased the expression of HSPB1 and decreased that of HSP30 in the tilapia hepatocytes, while the treatment that lasted for 2.5 h significantly increased the expressions of HSP90a and HSPB1. A pretreatment of curcumin for 24 h on the cells not only significantly elevated the expressions of HSP70, HSP90α, HSP30, and HSPB1 over control but also on those of HSP70, HSP90α, and HSP30 under 1 h H₂O₂ stress, as well as those on HSP90α, HSP30, and HSPB1 under 2.5 h H₂O₂ stress. However, no significant differences in other HSPs were observed.

  Conclusion   As a spontaneous response of tilapia hepatocytes to oxidative stress, H₂O₂ affected significantly the expressions of HSP90a, HSP30, and HSPB1 in the cells. By pretreating the hepatocytes with curcumin, expressions of these genes could be uplifted boosting the cellular antioxidant capacity to better resist the stress and maintain viability.