Design and synthesis of mitochondria-targeted betulinic acid derivatives with antipancreatic cancer activity via ROS-mediated apoptosis and ferroptosis.

BACKGROUND

Pancreatic cancer is a highly lethal malignancy that is frequently accompanied by drug resistance. Betulinic acid (BA) has therapeutic potential; its clinical utility is hampered by poor solubility and a lack of organelle-specific targeting. Given the functional abnormalities of tumor mitochondria, mitochondria-targeted interventions may enhance therapeutic efficacy while reducing systemic toxicity.

METHODS

Using BA as the parent scaffold, we designed and synthesized 30 mitochondria-targeted BA derivatives by attaching delocalized lipophilic cations (DLCs), including triphenylphosphonium (TPP+), at the C-28 position. We performed in vitro activity screening, transcriptomic analysis, mechanistic validation, and in vivo efficacy and safety assessments.

RESULTS

Compound 14 showed the strongest cytotoxicity against PANC-1 cells (IC50 = 1.36 ± 0.09 μM), which was markedly superior to BA (IC50 = 79.29 ± 6.87 μM) with a fold reduction of approximately 58. Transcriptomics and mechanistic analysis indicate that compound 14 accumulated in mitochondria, inducing excessive ROS production, which then led to the collapse of mitochondrial membrane potential (ΔΨm) and mitochondrial dysfunction. This mitochondrial dysfunction subsequently promoted cytochrome c release and activated the caspase cascade, thereby triggering intrinsic mitochondrial apoptosis. Concurrently, compound 14 induced ferroptosis by upregulating ACSL4 and downregulating GPX4, which was accompanied by increased lipid peroxidation products and intracellular Fe2+. The ROS scavenger N-acetylcysteine significantly reversed these ferroptosis-associated changes. In vivo, compound 14 significantly inhibited tumor growth in xenografts without evident systemic toxicity.

CONCLUSION

Compound 14, a mitochondria-targeted BA derivative, inhibits pancreatic cancer via ROS-driven mitochondrial apoptosis and ferroptosis, showing favorable efficacy and safety and potential for preclinical development.