Chinese agarwood petroleum ether extract suppressed gastric cancer progression via up-regulation of DNA damage-induced G0/G1 phase arrest and HO-1-mediated ferroptosis

Gastric cancer (GC) refers to the cancer characterized by great morbidity and mortality. Chinese agarwood represents the resin-containing wood of Aquilaria sinensis (Lour.) Gilg., which is used to treat asthma, cardiac ischemia, and tumors. However, in-depth studies on the anti-GC effects of Chinese agarwood and the underlying mechanism are lacking. Herein, Chinese agarwood petroleum ether extract (CAPEE) had strong cytotoxicity to human GC cells, with IC₅₀ values for AGS, HGC27, and MGC803 cells being 2.89, 2.46, and 2.37 μg/mL, respectively, at 48 h. CAPEE remarkably promoted apoptosis of these GC cells, and BCL-2 associated x protein (BAX)/BCL-2 antagonist killer 1 (BAK) was probably related to CAPEE-mediated apoptosis. Additionally, CAPEE arrested cell cycle at G0/G1 phase within human GC cells via the activation of DNA damage-p21-Cyclin D1/Cyclin-dependent kinase 4 (CDK4) signaling axis, and CAPEE elevated Fe^{2 +} , lipid peroxides and reactive oxygen species (ROS) levels within human GC cells, which thus induced ferroptosis. RNA sequencing, qRT-PCR, and western blotting results revealed that CAPEE up-regulated the expression of heme oxygenase-1 (HO-1) within human GC cells. Using RNA interference, we found that knocking down HO-1 expression weakened CAPEE sensitivity in human GC cells and inhibited ferroptosis of human GC cells induced by CAPEE. Additionally, CAPEE administration displayed strong in vivo anti-GC activity, and there were no significant toxic effects of administering CAPEE on nude mice. Moreover, administering CAPEE inhibited tumor cell growth in tumor tissues and promoted apoptosis of tumor tissues. Therefore, CAPEE suppressed human GC cell growth by up-regulating the DNA damage-p21-Cyclin D1/CDK4 signaling axis and HO-1-mediated ferroptosis. CAPEE is the candidate drug used to treat GC.