Homoharringtonine (HHT) has been used in leukemia therapy since the 1970s. Its inhibitory effects on solid tumors have attracted increasing interest and have been actively explored in recent years. This study investigates the therapeutic effects and pharmacological mechanisms of HHT on pancreatic cancer, focusing on mitochondrial energy metabolism and macrophage sensitivity to HHT. HHT significantly inhibited the proliferation and colony formation of pancreatic cancer cell lines PANC-1 and Pan02 in vitro and suppressed tumorigenic potential in vivo. The mechanistic study revealed that HHT induced a significant elevation of reactive oxygen species (ROS) levels in pancreatic cancer cells over time, as evidenced by the enhanced dichlorodihydrofluorescein diacetate fluorescence and an elevated NAD+/NADH ratio. This resulted in mitochondrial respiratory dysfunction, including reductions in basal respiration, maximal respiration, and adenosine triphosphate production. In addition, HHT caused cell cycle arrest and disrupted the cytoskeleton, thereby inhibiting cell division and proliferation. The anti-tumor effects of HHT were further evaluated using a subcutaneous pancreatic tumor-bearing mouse model, showing that HHT inhibited the proliferation of pancreatic tumor cells in vivo, which led to reduced tumor mass. Moreover, HHT significantly reduced the viability of macrophages both in vitro and in vivo, leading to the depletion of tumor-associated macrophages in the tumor microenvironment (TME), thereby alleviating immune suppression. In conclusion, HHT effectively inhibits pancreatic cancer progression through upregulating cellular ROS levels over time, thereby disrupting mitochondrial respiratory capacity in tumor cells and reducing macrophage populations, contributing to TME reprogramming and immune restoration.

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