Anti-breast cancer activity of curcumin on the human oxidation-resistant cells ZR-75-1 with gamma-glutamyltranspeptidase inhibition.

Since curcumin, a polyphenol extracted from the rhizomes of Curcuma longa L. (Zingiberaceae), has been proposed for breast cancer chemoprevention, the aim of the present work was to determine if it had anti-tumour effects on mammary cells which are resistant to oxidative damage. ZR-75-1 cells were treated with curcumin and copper(II) sulphate in order to evaluate cell death and gamma-glutamyltranspeptidase (GGTP) activity. Curcumin was cytotoxic in a dose-dependent manner (loss of viability with lactate-dehydrogenase release) with apoptotic effects on ZR-75-1 cells. Also, curcumin displayed an antioxidant effect only on the copper-oxidized cells. The GGTP activity was decreased in a dose-dependent manner by curcumin, with the changes in this parameter accounting for neoplastic inhibition (direct relation between the enzyme activity and cellular viability). Summing up, our results suggest that curcumin induced apoptosis in ZR-75-1 with an antioxidant activity performed on those treated with copper(II) sulphate, which should be explored more thoroughly with the involvement of the GGTP enzyme activity as biomarker of their malignancy.