Galactosylated chitosan/5-fluorouracil nanoparticles inhibit mouse hepatic cancer growth and its side effects

AIM： To observe the curative effect of galactosylated chitosan （GC）/5-fluorouracil （5-FU） nanoparticles in liver caner mice and its side effects. METHODS： The GC/5-FU nanoparticle is a nanomate- rial made by coupling GC and 5-FU. The release experiment was performed in vitro. The orthotropic liver cancer mouse models were established and divided into control, GC, 5-FU and GC/5-FU groups. Mice in the control and GC group received an intravenous injection of 200 μL saline and GC, respectively. Mice in the 5-FU and GC/5-FU groups received 200 μL （containing 0.371 mg 5-FU） 5-FU and GC/5-FU, respectively. The tumor weight and survival time were observed. The cell cycle and apoptosis in tumor tissues were monitored by flow cytometry. The expression of p53, Bax, Bcl-2, caspase-3 and poly adenosine 50-diphosphate-ribose polymerase 1 （PARP-1） was detected by immunohistochemistry, reverse transcription-polymerase chain reaction and Western blot. The serum blood biochemical parameters and cytotoxic activity of natural killer （NK） cell and cy- totoxicity T lymphocyte （CTL） were measured. RESULTS： The GC/5-FU nanoparticle is a sustained release system. The drug loading was 6.12% ± 1.36%, the encapsulation efficiency was 81.82% ± 5.32%, and the Zeta potential was 10.34 ± 1.43 mV. The tu- mor weight in the GC/5-FU group （0.4361±0.1153 g vs 1.5801 ± 0.2821 g, P 〈 0.001） and the 5-FU （0.7932±0.1283 g vs 1.5801 ±0.2821 g, P 〈 0.001） was sig- nificantly lower than that in the control group; GC/5- FU treatment can significantly lower the tumor weight （0.4361± 0.1153 g vs 0.7932±0.1283 g, P 〈 0.001）, and the longest median survival time was seen in the GC/5-FU group, compared with the control （12 d vs 30 d, P 〈 0.001）, GC （13 d vs 30 d, P 〈 0.001） and 5-FU groups （17 d vs 30 d, P 〈 0.001）. Flow cytom- etry revealed that compared with the control, GC/5- FU caused a higher rate of G0-G1 arrest （52.79% ± 13.42% vs 23.92%±9.09%, P = 0.014 ） and apopto- sis （2.55% ±1.10% vs 11.13% ±11.73%, P 〈 0.001） in hepatic cancer cells. Analysis of the apoptosis path- ways showed that GC/5-FU upregulated the expression of p53 at both the protein and the mRNA levels, which in turn lowered the ratio of Bcl-2lBax expression; this led to the release of cytochrome C into the cytosol from the mitochondria and the subsequent activation of caspase-3. Upregulation of caspase-3 expression de- creased the PARP-1 at both the mRNA and the protein levels, which contributed to apoptosis. 5-FU increased the levels of aspartate aminotransferase and alanine aminotransferase, and decreased the numbers of platelet, white blood cell and lymphocyte and cytotoxic activities of CTL and NK cells, however, there were no such side effects in the GC/5-FU group. CONCLUSION： GC/5-FU nanoparticles can significant- ly inhibit the growth of liver cancer in mice via the p53 apoptosis pathway, and relieve the side effects and im- munosuppression of 5-FU.