Piceatannol and Pumpkin Seed Oil Synergistically Promote Apoptosis of PC3 Prostate Cancer Cells via Intrinsic Mitochondrial Pathway

<b>Purpose:</b> Piceatannol (PIC) is a polyphenolic stilbene that occurs naturally in various fruits and vegetables. Despite its well-documented anticancer activity, PIC has poor pharmacokinetic properties. Pumpkin seed oil (PSO) has well-known antiproliferative activities on prostate cells. This study aimed to enhance the cytotoxicity of PIC in PC3 prostate adenocarcinoma cells by incorporating PIC into a PSO-based self-emulsifying drug delivery system (PIC-PSO SEDDS). <b>Methods:</b> PIC solubility was investigated along with PSO. Then, the percentage of selected components used in the formulation was optimized to achieve minimum globule size. <b>Results:</b> The optimized PIC-PSO SEDDS was evaluated for its cytotoxicity, cell cycle distribution, apoptotic activities, reactive oxygen species (ROS), and mitochondrial membrane potential (MMP) in PC3 cells. The optimized formula exhibited a globule size of 576.00 ± 39.74 nm. PC3 cells treated with PIC-loaded PSO SEDDS had considerably higher antiproliferative activity than PIC, with an IC₅₀ value of 6.37 ± 0.41 μM. Combination index analysis revealed strong synergistic interactions between PIC and PSO, with a value of 0.24. PIC-PSO SEDDS also caused considerable G2 arrest by downregulating <i>CDK1</i> mRNA expression. In addition, the formulation significantly increased the apoptotic cell percentage, increased caspase-3 concentration, upregulated <i>BAX</i>, and <i>CYCS</i> mRNA expression, and downregulated <i>BCL2</i> mRNA expression. These effects were associated with enhanced generation of ROS and a decrease in MMP. <b>Conclusion:</b> Based on these results, incorporating PIC into PSO-based SEDDS improves its pro-apoptotic activity against PC3 cells. This involves, at least partly, induction of the intrinsic mitochondrial apoptosis pathway.