Effects of Ultrasound Contrast Agent-Encapsulated Paclitaxel Extract on the Proliferation and Invasion Ability of Hepatocellular Carcinoma Cells

Regarding to the limitations of paclitaxel (PTX) in cancer treatment, PTX was extracted from Taxus chinensis and PTX nano-ultrasound contrast agents (NUCA) were prepared to investigate their impacts on proliferation and invasion of hepatocellular carcinoma (HCC) cells (HCCCs). The PTX extract was obtained through extraction and multi-step purification methods using Taxus chinensis as the source material and poly(lactic-co-glycolic acid)-carboxylic acid (PLGA-COOH) as the experimental material. A modified double emulsion solvent evaporation (DESE) method was employed to prepare paclitaxel-loaded PLGA NUCA (PLGA@PTX). The particle size distribution (PSD) and zeta potential (ZP) of PLGA@PTX were identified using a laser particle size (PS) analyzer, while the drug-loading capacity (DLC) and encapsulation efficiency (EE) of PTX in PLGA@PTX NUCA were evaluated using high-performance liquid chromatography (HPLC). The in vitro release rate (IVRR) of PTX from PLGA@PTX NUCA was also analyzed. HepG2 lines, a human HCC cell line, were grouped into four randomly: a blank control group (Blank), a PTX group, a blank nano-contrast agent group without PTX encapsulation (PLGA), and a PTX-loaded NUCA group (PLGA@PTX). In the Blank group, HepG2 lines were cultured conventionally for 12 hours, while PTX or PLGA@PTX was added to the PTX and PLGA@PTX groups, respectively, to achieve a required concentration (10(-7) mol/L) of PTX. An equal amount of PLGA nanoparticles was added to the PLGA group. 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) and Transwell were utilized to judge the impacts of PLGA@PTX nanoparticles on proliferation and invasion of HepG2 lines, respectively. Moreover, flow cytometry (FCT) was utilized to examine the influence of PLGA@PTX nanoparticles on cell cycle (CC) and apoptosis of HepG2 lines. The results revealed that the purity of the PTX extract was as high as 99.04 +/- 0.92%. The average PS of PLGA@PTX NUCA was (432.79 +/- 4.56) nm, with a surface potential of (-10.79 +/- 2.28) mV. Furthermore, the EE and DLC were (89.27 +/- 2.63) % and (9.03 +/- 0.29) %, respectively. The inhibition rate (IR) to HepG2 lines and cell invasion and the apoptotic rate (AR) in the PLGA@PTX group were much higher to those in the PLGA and PTX groups (P < 0.01, P < 0.05). The ratio of G1/G0 phase in the CC was greatly lower in the PLGA@PTX group to the PLGA and PTX groups, showing obvious differences with (P < 0.05), while that of G2/M phase was higher (P < 0.05). These findings indicated that the prepared PLGA@PTX NUCA hindered the proliferation and invasion of HepG2 lines and induced CC arrest at the G2/M phase and apoptosis.