Research On The Anti-human Hepatocellular Carcinoma Effects Of Aminopolysaccharide Nanoparticles And The Mechanisms Involved

Aminopolysaccharide is naturally occurred cationic polysaccharide.Its special set of properties, which include low or no toxicity, biocompatibility, biodegradability, low immunogenicity, make it useful in a variety of applications including biomedicine Pharmaceuticals, and food additives. Because of their recognized mucoadhesivity and ability to enhance the penetration of large molecules across mucosal surface, aminopolysaccharide nanoparticles are mainly studied as a drug carrier for control release, and targeted delivery. Previous researches of our group indicated that aminopolysaccharide nanoparticles have antitumor activities, which make them potentially useful in tumor therapy.Aimed to provide a scientific basis for applicating the aminopolysaccharide nanoparticles in human hepatocellular carcinoma (HCC) therapy, the effects of the aminopolysaccharide nanoparticles on HCC were evaluated and the involved mechanisms were investidated through hepatocellular carcinoma cell (BEL-7402) culture and nude mice hepatocellular carcinoma xenograft (SMMC-7721) mode in this study.The results as follows:1 The deacetylation degree (D.D.) of aminopolysaccharide was decreased by the acetylation of acetic anhydride. The aminopolysaccharides with different D.D were prepared to be nanoparticles. Compared with the high D.D. aminopolysaccharide nanoparticles, the low D.D aminopolysaccharide nanoparticles have bigger particle sizes and lower zeta potential which make them distributed in solutions unevenly with poor stability. Although all of these two kind aminopolysaccharide nanoparticles elicited dose-dependent inhibitory effects on the proliferation of BEL7402 cells in a certain concentration range, the high D.D. aminopolysaccharide nanoparticles display a much stronger effects than the low D.D.ones. These results indicate that the free amino groups on aminopolysaccharide molecule not only are important to the morphologic and physicochemical characteristics of the nanoparticles but also critical to their antitumor activities.2. Sphingomyelinase (SMase) activity analysis of the tumor cell protein extraction indicated that aminopolysaccharide nanoparticles caused the increasing of acidic SMase and neutral SMase activities in tumor cells, which may one of the mechanisms involved in tumor cell death induced by aminopolysaccharide nanoparticles.3 The results of human hepatocelluar carcinoma xenografts experiment showed aminopolysaccharide nanoparticles and Adriamycin inhibited the tumor growth significantly (p<0.05). Compared with the negative control group, the values of relative tumor proliferation rate (T/C) (21 days) in the aminopolysaccharide nanoparticles group and Adriamycin group were 61.68%and 48.67%respectively. Histological examination of xenograft,liver and lung tissues stained with H&E under microscope indicated the aminopolysaccharide nanoparticles and adriamycin significantly (p<0.01) improve the necrosis extend in tumors with the proportions of necrotic area in total tumor area were 42.25±3.83%and 35.26±11.87%respectively, compared with negative control group (20.61±3.84%). In addition, aminopolysaccharide nanoparticles can soften injures of liver and lung tissues caused by the tumor growth.4 Imunohistochemistry study results indicated aminopolysaccharide nanoparticles significently inhibited the vascular endothelial growth factor receptor2 (VEGFR2) (p<0.01) and proliferating cell nuclear antigen (PCNA) (p<0.05) expression in tumors while the expression of vascular endothelial growth factor (VEGF) was not affected. The transcription of VEGF and VEGFR2 were also analyzed by real-time quantitative polymerase chain reaction (RQ-PCR). Consistant with the protein expression results, the transcription of VEGFR2 was also significantly inhibited in aminopolysaccharide nanoparticles group, while the transcription of VEGF haven't any significance in the groups,which implicate that antitumor activity of aminopolysaccharide nanoparticles appears to be related to its antiangiogenic activity, which is correlated with VEGFR2 production and subsequent blockage of VEGF-induced endothelial cell activation. In addition, aminopolysaccharide nanoparticles may also inhibit the tumor growth through suppressing the prolification activity of tumor cells.Therefore, aminopolysaccharide nanoparticles can efficiently inhibit the growth of human hepatocelluler carcinoma through activating the sphingomyelinase in the tumor cells, and suppressing the expression of VEGFR2 and PCNA in the tumor tissues.