Transferrin-functionalized co-delivery microemulsion of β-elemene and celastrol for synergistic anti-colorectal cancer treatment / 中草药

ABSTRACT

Objective To verify the synergistic effect of transferrin modified β-elemene and celastrol co-loaded microemulsion (Tf-EC-MEs) on anti-colorectal cancer treatment. Methods The optimal mass ratio of β-elemene and celastrol to growth inhibition of Lovo and HT-29 colorectal cancer cells was optimized by MTT staining method in vitro. Tf-EC-MEs was prepared by “mixing-dripping” method, and the preparation and physicochemical properties of the particles were characterized by high performance liquid chromatography (HPLC), laser particle analyzer, and transmission electron microscope. The MTT staining, HPLC-BCA combined method, and Annexin V-PE/7-Aminoactinomycin D (Annexin V-PE/7-AAD) kit were used to investigate the antitumor activity of Tf-EC-MEs in vitro, and its effect on cell uptake, and apoptosis of tumor cells. The tumor-bearing nude mice model was established by subcutaneous injection of Lovo cells, and the tumor growth, weight, and survival time were observed after intravenous injection of β-elemene + celastrol, β-elemene-celastrol co-loaded microemulsion (EC-MEs), and Tf-EC-MEs. Results The combined administration of β-elemene and celastrol (401) had significant synergistic effect on the anti-colorectal cancer of Lovo and HT-29 cells. IC50 of β-elemene + celastrol in Lovo and HT-29 cells were (17.5 ± 2.9) and (36.4 ± 3.6) μg/mL, with the CI as 0.89 and 0.96, respectively. IC50 of Tf-EC-MEs in Lovo and HT-29 cells were (11.7 ± 0.6) and (27.4 ± 1.2) μg/mL, with the CI as 0.61 and 0.72 respectively. The 4 h of Lovo uptake of Tf-EC-MEs was 7.2 μg/mg, which was 3.3 times higher than that of β-elemene + celastrol. Tf-EC-MEs induced apoptosis in 59.2% of Lovo cells, which was significantly higher than that in beta-elemene + celastrol and EC-MEs groups. Tf-EC-MEs showed the overwhelming inhibition of growth of Lovo tumor-bearing tumors. The survival rate of Tf-EC-MEs-treated mice was 37.5% at day 60. In Tf-EC-MEs treated group, HE staining sections of tumor tissues showed substantial cell necrosis and the Ki-67 immunohistochemical sections displayed the significant inhibition of proliferation of tumor cells. Conclusion Compared with the combination group (beta-elemene and celastrol) and EC-MEs groups, Tf-EC-MEs has a promising potential in the synergistic anti-colorectal cancer treatment.