2.1. Cell Culture and Reagents

Three CRC cell lines with different p53 statuses were used in this study: HCT-116 (p53 wild-type), HCT-116 p53 -/- (p53 null), and HT-29 (p53 mutated). HCT-116 and HCT-116 p53 null were obtained from Horizon Discovery (Cambridge, UK). HT-29 cells were obtained from American Type Culture Collection (ATCC, Rockville, MD, USA). All cell types were cultivated in RPMI-1640 medium (Gibco, Carlsbad, CA, USA) supplemented with 2 mM L-glutamine, 10% FBS, and a 1% antibiotic-antimycotic cocktail containing penicillin (100 U/mL), streptomycin (100 μg/mL), and amphotericin B (250 ng/mL) (Gibco, Carlsbad, CA, USA) at 37 °C with 5% CO₂.

CORM3, biliverdin, hemin, and CoPPIX were purchased from Sigma-Aldric Co. (St. Luis, MO, USA). Bosentan was purchased from Selleckchem (Houston, TX, USA).