Explore The Influence Of Aptamer-protamine-siRNA Nanoparticle In Targeted Cancer Therapy

Cancer therapy is still a difficult subject for doctors and pharmacists, although some radical operations could prolong some cancer patients'5 years or 10 years survival rates, the recurrence of most cancers still need us to deal with, maybe chemotherapy and radiotherapy could make benefits for some patients, but the side effects of them, for example, the normal tissues toxicities of chemotherapy and regional tissues adhesions of radiotherapy still can not be avoided. RNAi might be a good choice for cancer therapy. RNAi therapy is a new and hot way to treat disease by targeting specified genes strongly associated with disease. From the day of discovering RNAi in Caenorhabditis elegans and subsequently the exploration of siRNA in mammalian cells, these years'researches on RNAi have acquired large achievements. It has been not only a tool of gene research in laboratory, but also a way in clinical trials for some diseases therapy. But there are still many problems in RNAi applications, the main of which is the delivery. In recent times, formulations of RNAi in vivo research are mainly as conjugated with cholesterol or aptamer, embedded by liposome or lipoplexes, complexed with peptides or polymers and fused with antibodies. Although these methods of using siRNA could meet the results of silencing specified genes, but there are still some problems to be resolved, such as lack of targeted cell characteristics or high cell membrane toxicities. So, this gives us the enthusiasm to find a safe and effective way to deliver siRNA into targeted cells.Here we designed a way to use siRNA, which is complexed with protamine and aptamer, so we called aptamer-protamine-siRNA nanoparticle. Then we performed four parts of experiments to verify the potency of the nanoparticle:(1) aptamer-parotamine-FAMsiRNA could be uptaken by cells, (2) aptamer-protamin-siEGFP could downrelgulate the expression of EGFP, (3) aptamer-protamine-sisurvivin could inhibit the expression of survivin, and the cell growth was obviously slower than the control group, some cells went to apoptosis. (4) in vivo test of the interfering effect of aptamer-protamine-siRNA in nude mice, we found that the tumors in aptamer-protamine-sisurvivin nanoparticle group were significantly smaller than vehicle group, and the expression of survivin could also be inhibited in vivo, the cell proliferation in nanoparticle group was significantly inhibited by the detection of PCNA and Ki67, also in this research we explored that growth hormone might have the ability to promote cancer cell's proliferation which could increase the sensitivity of cancer cells to targeted therapy.Our research showed that aptamer-protamine-siRNA nanoparticle was an effective delivery to carry siRNA into cells and the siRNA could take part in the gene-silence activities. It could not only be a good delivery of siRNA in vitro tests but also be proved to be effective in vivo experiments. This nanoparticle could recognize targeted cells which express aptamer conjunctive antigens by aptamer, the siRNA it carried could inhibit the expression of specified gene, so aptamer-protamine-siRNA nanoparticle could act as a targeted RNAi delivery. This nanoparticle could be used not only on breast cancer but also on other cancers and other diseases just by changing the aptamer to another specified antigen conjunctive aptamer and replacing the siRNA to another gene siRNAs, so aptamer-protamine-siRNA nanoparticle might become a good method for gene silencing research and even for clinical diseases therapy.