HMOX1 and cancer: PPIX nanoparticles have been extensively studied for photodynamic therapy in cancer treatment.16,17 PPIX NPs have also been investigated as antibacterial agents due to ROS production.18 Metal-chelated PPIX, such as ZnPPIX NPs, have been proposed as potential anticancer agents due to HO-1 inhibition.19 In contrast, CoPPIX is an inducer of HO-1, which may increase the survival of cell lines by protecting against ROS.