A novel melittin nano-liposome exerted excellent anti-hepatocellular carcinoma efficacy with better biological safety

Abstract

Melittin is the main effective component of bee venom and has extensive biological functions; however, serious side effects have restricted its clinical application. Preclinical and clinical studies showed that the main adverse events were allergic reaction and pain at the administration site. To decrease the toxicity, we prepared melittin nano-liposomes by encapsulating melittin with poloxamer 188 and explored the inhibitory activities on liver cancer together with biological safety. Here, we showed that melittin nano-liposomes significantly inhibited the survival of hepatocellular carcinoma (HCC) cells in vitro and prominently suppressed the growth of subcutaneous and orthotopic HCC transplantation tumors in vivo. It was important that it induced less inflammation and allergy in mice compared with melittin. Overall, melittin nano-liposomes would have a better application in HCC therapy due to its significant anti-tumor activity and better biological safety.

Keywords: Anti-tumor activity; Bee venom; Biological safety; Melittin nano-liposomes.

Fig. 1

Melittin nano-liposomes induced apoptosis in hepatic carcinoma cells in vitro and vivo and inhibit hepatocellular carcinoma in LM-3 xenograft tumor model. a HepG2 cells were cultured with vehicle, blank liposomes (2 μM), melittin (2 μM), or melittin nano-liposomes (2 μM) for 24 h, stained with annexin V-FITC and PI, and analyzed by flow cytometry. b Western blot analysis of apoptosis-related proteins after HepG2 cells were treated with vehicle, liposomes (2 μM), melittin (2 μM), or melittin nano-liposomes (2 μM) for 24 h. c HepG2 cells were pretreated with or without the caspase inhibitor Z-VAD-FMK for 6 h and then treated with vehicle, liposomes (2 μM), melittin (2 μM), or melittin nano-liposomes (2 μM) for 24 h. Western blot analysis of Bcl-2 and procaspase-3 was carried out subsequently. d TUNEL assay for detecting apoptosis in tumor tissues of the hepatocellular carcinoma Hepa 1-6 orthotopic tumor model. e Western blot analysis of apoptosis-related proteins of Hepa 1-6 tumor tissues. f Live imaging photos and the fluorescence degree of vehicle, blank liposomes (8 mg/kg), melittin (2 mg/kg), melittin nano-liposomes (2, 4, and 8 mg/kg), and sorafenib (30 mg/kg) treated groups in the LM-3 orthotopic implanted tumor model. The data are presented as the mean ± SEM. Statistical significance was calculated using Student’s t test (*p ≤ 0.05)

Fig. 2

Melittin nano-liposomes showed reduced toxicity in vivo. a Photos of the tails of each group at the end point of treatment. These mice were from the LM-3 model. b TUNEL assay for detecting apoptosis in the liver tissue after mice (n = 10) were treated with vehicle, blank liposomes (8 mg/kg), melittin (2 mg/kg), and melittin nano-liposomes (2 mg/kg) for 2 weeks. c Peripheral blood was collected from the ICR mice and analyzed by automated hematology analyzer