Calcitriol, the hormonal form of vitamin D, potentiates the activity of some common
anticancer drugs and agents of the anticancer immune system, including tumor necrosis
factor α (TNFα). TNFα‐induced cytotoxicity is due to both caspase‐dependent and‐
independent pathways. Cotreatment with calcitriol enhanced both modes of TNFα‐induced
death in MCF‐7 breast cancer cells. It increased caspase‐3‐like activity as assayed by the
cleavage of poly‐(ADP‐ribose) polymerase and of the fluorogenic substrate ac‐DEVD …

Calcitriol, the hormonal form of vitamin D, enhanced TNF‐induced cytotoxicity in MCF‐7
breast cancer cells. It increased the induction of caspase‐3‐like activity and TNF‐induced
caspase‐independent cytotoxicity in the presence of a pan‐caspase inhibitor. The
antioxidants N‐acetylcysteine, glutathione, lipoic acid, and ascorbic acid markedly reduced
the effect of the hormone on TNF‐induced caspase activation, attesting to the involvement of
reactive oxygen species (ROS) in the cross‐talk between the hormone and the cytokine …