CETZOLE Analogs as Potent Ferroptosis Inducers and Their Target Identification Using Covalent/Affinity Probes

Ferroptosis
is a recently discovered cell death mechanism triggered
by iron-dependent elevation of reactive oxygen species leading to
lipid membrane peroxidation. We previously reported the development
of a new class of ferroptosis inducers referred to as CETZOLEs with
CC50 values in the low micromolar range. Structure–activity
relationship study of these compounds led to the development of more
potent analogs with CC50 values in the nanomolar range.
Cells exposed to these compounds displayed the hallmarks of ferroptosis
including cell death through ROS accumulation. Cancer cells were found
to be more sensitive to these compounds than normal cells. Proteomic
studies using covalent and affinity probes led to the identification
of cystathionine β-synthase, peroxiredoxins, ADP/ATP carriers,
and glucose dehydrogenase as enriched proteins. The binding of CETZOLEs
to these proteins as well as GPX4 was validated by Western blotting.
This group of proteins is known to be associated with cellular antioxidant
pathways.