Phenylboronic Acid-functionalized Polyamidoamine-mediated MiR-34a Delivery For The Treatment Of Gastric Cancer

Gastric cancer is a common malignant tumor and one of the important factors that cause tumor-related death.In the past few decades,with the continuous development of science and technology and the well understanding of gastric cancer,the incidence,diagnosis and therapeutic options have been turned upside down.However,due to the occultation of early digestive system tumors,most patients have developed advanced gastric cancer when they have been diagnosed gastric cancer,and the prognosis of advanced gastric cancer is relatively poor.Therefore,how to treat gastric cancer more effectively is still a hot topic.In recent years,a variety of methods for the treatment of gastric cancer have emerged in an endless stream.In addition to traditional surgical treatment and chemotherapy,immunotherapy and targeted drug therapy have achieved good results.However,as the treatment progresses,the drug resistance of the tumor still increase.Therefore,the above treatments still have defects,and other treatment methods need to be explored.If you can more clearly understand the role of genes in the development of tumors,then new ideas and methods for treating tumors will be explored.In many types of tumors,dysfunction of oncogenes and tumor suppressor genes plays a crucial role in the development of tumors.As an important treatment,gene therapy can start from the source of the disease to achieve the purpose of treatment,it has received more and more attention because of its inherent advantages.From 1989 to 2008,tumors were the main target of gene therapy clinical trials,accounting for 66% of all gene therapy clinical trials.Gene therapy of tumors is mainly reflected in four aspects: down-regulating the expression of oncogenes,enhancing the expression of tumor suppressor factors,inducing tumor cell death,inhibiting neovascularization around the tumor,and mobilizing the immune system to achieve anti-tumor effects.Small non-coding Ribo Nucleic Acids(sncRNA),siRNA,shRNA and microRNA,play an extremely important role in the process of gene regulation and participate in various biological processes in vivo.Therefore,research on the application of sncRNA is also emerging.In the treatment of tumors,it can effectively reduce or increase the abnormally expressed proteins in the cells,leading to the death of tumor cells,thereby achieving the purpose of treating tumors.The biggest limitation of treatment with RNA interference(RNAi)technology is the lack of safe and effective delivery vehicles in vivo,including drug targeting and maintenance of circulating time in the body.In this paper,the polymer dendrimer PAMAM was used as the backbone,and polyethylene glycol(PEG)was used as the cross-linking agent to link the phenylboronic acid(PBA)targeting group to thepolymer material polyamide-amine(PAMAM).A PAMAM-PEG-PBA delivery vector with specific targeting function for gastric cancer BGC-823 cell line.According to the experimental results,this vector has good loading and protection ability for miR-34 a.It is effective to transfect miR-34 a into tumor cells.We evaluated the delivery system at the cellular and animal levels,respectively.At the cellular level,proliferation inhibition assays,transwell assays,colony formation assays,double staining apoptosis assays,wound healing assays,and western blot assays have shown that PPP/miR-34 a nanocomplexes can effectively inhibit tumor cell proliferation,migration,promote BGC-823 cell apoptosis.At the animal level,PPP/miR-34 a nanocomposites were injected into the tail vein of mice by subcutaneous allogeneic tumor implantation model,and the nanocomposites were imaged in mice at 2 h and 6 h respectively to observe the localization of nanocomposites.From the results,we can prove that the small nucleic acid drug delivery system has good biocompatibility with the organism,also it can resist the metabolism of the kidney,liver,etc.,thereby maintaining a long time of drug circulation both in the body and in vitro tumor sites with significant accumulation.It can be observed from the results of the tumor inhibition test that the delivery system can well control the tumor growth without significant interference with the nutritional status of the mouse.The results of Tunel staining and Ki-67 immunohistochemistry showed thatthe nanocomplex could promote the apoptosis of tumor tissues.In addition,HE staining of various organs of nude mice showed no obvious toxic effects,thus demonstrating the safety of the delivery system.In summary,we have established a biological model of gastric cancer,and the delivery of a small nucleic acid system with a PAMAM-based targeting vector can effectively kill gastric cancer cells and inhibit their ability to proliferate and migrate.Our research shows that the small nucleic acid delivery system has good biological behavior and has great potential in anti-tumor therapy,which can help to establish a better tumor treatment strategy in the future.Conclusion:1.We constructed a dendrimer PAMAM as a backbone,polyethylene glycol(PEG)as a cross-linking agent,and phenylboric acid(PBA)as a targeting ligand to PAMAM.Through the physicochemical properties of newly synthesized materials,ability to target cells,anti-tumor proliferation,and migration ability.The experimental results show that the delivery system can load and protect miR-34 a by electrostatic adsorption,and phenylboronic acid can efficiently transfect miR-34 a into cells by specifically binding to the sialic acid receptor on the surface of BGC-823 cell line.In order to induce apoptosis,inhibition of cell proliferation and migration.2.From the animal level,we established the tumor-bearing mice to study the distribution of drugs in the nanoparticle composite object,inhibit the growth of tumor cells,and whether it has toxic effects on organs.From the experimental results,our established nanomaterial delivery small molecule ribonucleic acid system can circulate in mice for a long time and have a high accumulation in tumor tissues.From the tumor inhibition effect,PPP/miR-34 a can effectively inhibit tumor growth,and the PPP/miR-34 a nanoparticle complex can be proved at the animal level again by HE staining,Tunel staining and Ki-67 immunohistochemical staining,which can effectively inhibit tumor cell growth.