Effects of estrogen on the stress response in CuSO4-exposed PLHC-1 cells

As part of an effort to validate the use of heat shock proteins (hsp) as a biomarker of adverse effect, we investigated the impact of estrogen (E2), the hormone responsible for vitellogenisis in fish, on the induction of hsp 60 and 70. PLHC-1 (Pociliopsis lucida hepatoma cell line) cells were cultured under standard conditions and treated with either 16 ppm copper; a known inducer of hsp 60 and 70, 1 microM estradiol, a combination of copper and estradiol, or media alone. Copper induced both hsp 60 and 70 two fold, while E2 alone had no effect. The combination of the copper and E2 inhibited the hsp 70 response, indicated by a 51% decrease in cellular hsp 70 compared to the copper treatment alone. In contrast, the expression of hsp 60 in the cells exposed to the copper-estradiol mixture was not significantly different than that in the copper-exposed cells. The results suggest that the use of hsp 70 induction in fish liver as a biomarker of effect may be limited by the gender and sexual maturity of the fish.