It is known that melatonin-induced apoptosis in cancer
cells is associated with ROS production [45, 54, 55], and
that oxidative stress determines cancer cells fate in response
to melatonin [11]. Here, we found a link between impaired
oxygen consumption, mitochondrial hyperpolarization and
oxidative stress generation in cells grown in the modified
galactose media and treated with melatonin. Although the
precise mechanism by which melatonin induces ROS in
cancer cells remains unknown, our results together with
data from other authors suggest that ROS produced by the
mitochondrial electron transport chain constitutes a key
factor in melatonin-induced cell death [39, 55–57] and
differentiation [50].