Antitumor and antimetastasis effects of carboplatin liposomes with polyethylene glycol-2000 on SGC-7901 gastric cell-bearing nude mice

The present study aimed to analyze the characteristics of polyethylene glycol (PEG)ylated carboplatin liposomes (PL-CBPs), including size, stability, their release, entrapping and loading efficiencies, and their antitumor and antimetastatic effects on the lymph nodes. The PL-CBPs were prepared using PEG-2000 with the thin film hydration method. The liposome size and release, entrapping and loading efficiencies were detected by ultra-violet/visible spectrophotometry. A nude mouse model was established with the SGC-7901 gastric cell line to evaluate the antitumor effect of the PL-CBP. After 7 days, the mice were randomly divided into three groups (the control, CBP, and PL-CBP groups). CBP and PL-CBP were administered at a dose of 10 mg/kg for two consecutive cycles of treatment, 5 days apart, to their respective groups. In each group, two doses of 5 mg/kg were administered every 48 h. The tumor weight and volume were detected, and the food intake and body weight were measured during the administration. Apoptosis in the tumor cells was evaluated by terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling and platinum (Pt) accumulation was detected by atomic absorption spectroscopy. Lastly, lymph node metastasis was evaluated by hematoxylin and eosin staining. The PL-CBPs were more stable when comapred with CBP alone, and the drug release efficiency was 0.7, 22.5, 48.7 and 65.1% at 37°C for 0, 12, 24 and 48 h. The results showed that the encapsulation efficiency was 85% and the loading efficiency was 0.15 mg/mg lipid. After 35 days, PL-CBP induced potent antitumor effects compared with the control and CBP groups (PL-CBP vs. control, P<0.01; PL-CBP vs. CBP, P<0.05). PL-CBP and CBP induced a lower and the lowest body weight and level of food intake, respectively, compared with the control group (CBP vs. control, P<0.05). The apoptosis rate and lymph node metastasis in the PL-CBP group was higher than that in the CBP and control groups (PL-CBP vs. control, P<0.01; PL-CBP vs. CBP, P<0.05). Pt accumulation in the tumors was higher in the PL-CBP group than in the CBP group (PL-CBP vs. CBP, P<0.05). The PL-CBPs were more stable in the circulation and could be released more slowly at the tumor site than compared with CBP injection. The PL-CBPs showed potent antitumor and antimetastatic effects on the lymph nodes.