Inhibition of proliferation and induction of apoptosis by melatonin in human myeloid HL-60 cells

Abstract

Melatonin is an indoleamine that is synthesized in the pineal glandand has an extensive repertoire of biological activities. In the present study,we found that melatonin reduced the growth of the human myeloid leukemiacells HL-60, inhibiting progression from G1toSphaseofthecellcycleandincreasing apoptotic cell death. Furthermore, melatonin treatment elevatedcytochromecrelease from mitochondria and augmented caspase-3 andcaspase-9 activities. Upregulation of Bax and downregulation of Bcl-2 wasalso observed upon melatonin treatment. The effects of melatonin werefound not to be mediated by membrane receptors for the indoleamine.Together, our results suggest that melatonin reduces the viability of HL-60cells via induction of apoptosis primarily through regulation of Bax/Bcl-2expression.