Novel 3′-diindolylmethane nanoformulation induces apoptosis, and reduces migration and angiogenesis in liver cancer cells

Liver cancer (LC) ranks as the second most prevalent cause of cancer-related deaths. Herbaceous plants are valuable sources of complementary, adjuvant, or alternative anti-tumor therapy as they contain natural active ingredients with anti-cancer potential. Although the clinical use of 3, 3′-Diindolylmethane (DIM) has been established, its low chemical stability and bioavailability, limits its therapeutic applications. Increasing effort has been undertaken to improve DIM's biological activity including nanoformulations. Here, we evaluated the efficacy of DIM nanoparticles (DIM-NPs) coated with PEG/chitosan for the treatment of liver cancer and elucidated the underlying molecular mechanisms contributing to its anti-tumor activity. DIM-PLGA-PEG/chitosan NPs were synthesized and characterized using dynamic light scattering (DLS). The effect of newly synthesized DIM-NPs was evaluated in HepG-2 and HUH-7 hepatocarcinoma cells and compared to THLE-2 immortal normal liver cells and WI-38 (normal lung fibroblast cells). These cells were treated with different non-cytotoxic concentrations of DIM-NPs and MTT assay and other functional assays were performed. Compared to normal cells, DIM-NPs induced cytotoxicity in HepG-2 cells at 6.25 µg/mL after 48 h of treatment. Treatment of HepG-2 cells with the 50 % inhibitory concentration (IC50) 12.5 µg/mL of DIM-NPs inhibited cell migration (p < 0.001). Treatment of chicken embryo with 5ug/ml DIM-NPs reduced (p < 0.001) angiogenesis at day 4. Notably, at the molecular level, DIM-NPs upregulated Bax and p53 and downregulated Bcl-2 in a dose-dependent manner. DIM-NPs also induced cell apoptosis in HepG-2 cells. Treatment of hepatic cells with DIM-NPs decreased cell proliferation, migration and angiogenesis, and induced cell death via up-regulation of Bax and p53, and down-regulation of Bcl-2 in HepG-2 cells. Further investigations are necessitated to determine the pharmacokinetics of DIM-NPs using a preclinical cancer model.