The new mechanism of apatinib in treating gastric cancer-related hypertension: dynamin-related protein 1-mediated pathological mitochondrial fission in endothelial cells

Abstract Background In cancer therapy, hypertension induced by VEGFR-TKI inhibitors significantly interferes with cancer treatment, and their vascular toxicity threatens patients' health. Most studies suggest that anti-angiogenic drugs may damage endothelial cell mitochondria, but related research is limited. Investigating the role of endothelial mitochondrial damage in apatinib-induced hypertension in gastric cancer is essential. Purpose To explore the mechanisms of endothelial cell mitochondrial damage leading to hypertension in apatinib-treated gastric cancer-bearing nude mice. Methods In vitro: Umbilical vein endothelial cells were divided into control, DMSO, and apatinib groups (treated with 2.5 µM apatinib for 48 hrs). ROS production and apoptosis rate were assessed by flow cytometry. Mitochondria were stained with Mitotracker and observed by confocal microscopy. WB measured NOX4, Caspase-3, Drp1, MFF, and Fis1 expression. Immunofluorescence detected Drp1/Fis1 co-localization. In vivo: Eighteen 5-week-old SPF male nude mice were divided into control (C, n=6), tumor (T, n=6), and tumor + apatinib (T+A, n=6) groups. MKN-45 cells were injected into the axillae. After tumor formation, the T group received 0.2ml saline by gavage daily, and T+A received 100mg/kg apatinib by gavage daily for one month. Blood pressure was measured every three days. Mitochondrial morphology was observed by TEM. Immunofluorescence measured DRP1 in aortic endothelial cells (CD31 labeled). WB assessed NOX4, Caspase-3, Drp1, MFF, and Fis1 in thoracic aorta. ImageJ was used to analyze protein levels. Statistical analysis was done using GraphPad 8.0.2. Results were expressed as mean ± SD, with P 0.05 considered significant. Results Apatinib treatment significantly increased ROS and apoptosis in endothelial cells, indicating mitochondrial damage. Confocal microscopy revealed excessive mitochondrial fission. In the apatinib group, NOX4, Caspase-3, Drp1, MFF, and Fis1 expressions were notably higher than in control and DMSO groups. Immunofluorescence showed increased co-localization of Drp1 and Fis1. In T+A-treated mice, systolic and diastolic blood pressures were significantly elevated. TEM showed excessive mitochondrial fission in aortic endothelial cells. Immunofluorescence revealed significantly higher DRP1 expression. In T+A group, NOX4, Caspase-3, Drp1, MFF, and Fis1 levels in thoracic aorta were higher than in control and tumor groups. In vivo experimental results are shown in Figure 1, and in vitro experimental results are shown in Figure 2. Conclusion Apatinib induces significant blood pressure elevation in gastric cancer-bearing nude mice and causes excessive mitochondrial fission and damage in endothelial cells, suggesting pathological mitochondrial fission. Mechanistically, apatinib activates DRP1 expression, and its interaction with Fis1 mediates pathological mitochondrial fission, leading to endothelial dysfunction and hypertension.Figure 1 Figure 2