Calcitriol induced redox imbalance and DNA breakage in cells sharing a common metabolic feature of malignancies: Interaction with cellular copper (II) ions leads to the production of reactive oxygen species.

Calcitriol is known to selectively kill malignant cells, however, not much is known about the mechanism by which it kills malignant cells and spares the "normal" cells. Since elevation of cellular copper is a metabolic condition common to all malignancies, we developed a mouse model to mimic this condition and treated the animals with calcitriol. It was observed that calcitriol-copper interaction in vivo causes severe fluctuations in cellular enzymatic and nonenzymatic scavengers of reactive oxygen species (ROS). Lipid peroxidation, a well-established marker of oxidative stress, was found to increase, and a substantial cellular DNA breakage was observed. Calcitriol-copper interaction in vivo was observed to lead the cells to an apoptosis like cell death. We propose that the interaction of calcitriol and copper within malignant cells and the consequent redox scavenger fluctuations and ROS-mediated DNA breakage may be one of the several mechanisms by which calcitriol causes selective cell death of malignant cells, while sparing normal cells.