In Vivo Evaluation Of The Anti-gastric Cancer Activity Of Britanin By Optical Imaging And Preparation Of Its Nano-delivery System

Bioluminescence imaging technology is widely used for real-time monitoring of in vivo tumor progression and physiological activities under drug effect due to its non-invasive properties.It is a novel tool for drug screening and drug evaluation.Britanin is a class of pseudoguaiacyl sesquiterpene lactones with in vitro anti-inflammatory activity found in Inula L.plants.In this project,a bioluminescence imaging platform for drug screening was constructed,which was based on luciferase substrates against gastric cancer-bearing mouse models.Through the platform,we studied the in vivo effects and metabolic information of the natural product Britanin on tumors and modified its formulation by the nanocarrier to obtain potential antitumor drug with high bioavailability and low toxicity and side effects.Britanin is derived from the traditional anti-inflammatory herb Inulae Flos.To date,there has been little research on the therapeutic effect of Britanin on cancer cells.In this study,cell viability assays and colony formation tests were performed to evaluate the anti-proliferative effect of Britanin on gastric cancer cells.After injecting Britanin into nude mice of BGC-823 gastric cancer cell line,the tumor development is monitored in real-time by bioluminescence imaging method.In order to explore the mechanism of Britanin,Western blot analysis was used to detect the expression changes of key molecules in the NF-κB signaling pathway,and ELISA was used to determine the expression of NF-κB downstream cytokines in the immune response.Cell test results showed that Britanin could suppress the proliferation of gastric cancer cells.Through in vivo small animal imaging and pathological examination,it was found that Britanin induced tumor tissue apoptosis,thereby inhibiting tumor development.In the treatment group,decreased levels of p65 and phosphorylated p65(p-p65)were observed,which suggests that NF-κB plays an important role in the antitumor effect of Britanin.In addition,increased levels of interleukin-2(IL-2)and decreased levels of IL-10 in the blood,indicate an enhanced immune response elicited by Britanin.In conclusion,Britanin has effective inhibitory activity on gastric cancer,and its anticancer effect possibly depends on the immune response involved by NF-κB.On this basis,Britanin was encapsulated with ferritin,a drug carrier with self-assembly and natural tumor targeting,in order to improve the bioavailability of nature product.Firstly,RGD-HFn(human ferritin H chain)was expressed by genetic engineering,and the purified ferritin carrier was obtained through Ni-NTA purification and ion exchange chromatography.Based on the self-assembly,TEM was used to characterize ferritin drug complex(RGDHFn-Britanin)after treatment with denaturant guanidine hydrochloride.The ferritin doxorubicin(Dox)complex(RGD-HFn-Dox)synthesized simultaneously was employed as a model drug to study the antitumor activity of ferritin-encapsulated drugs in vitro.After 24 h incubation with cancer cells,the fluorescence emission of Dox was observed through a confocal fluorescence microscope to assess the effect of ferritin drug carriers on cellular uptake.In the cell viability test of SGC-7901 cells,RGD-HFn-Dox showed a significantly enhanced inhibitory effect over free Dox.Fluorescence image exhibited that ferritin nanocages could improve the uptake and distribution of chemotherapy drugs in gastric cancer cells.Drug release tests are performed in different p H buffers.The results proved that the ferritin drug complex has certain stability,and acidic conditions could promote the release of the drug in the ferritin cage.From the good performance of RGD-HFn as a generic drug carrier in a model drug complex,it is inferred that ferritin-Britanin nano-delivery system is highly feasible for improving the antitumor efficacy of Britanin.In this study,the anti-gastric cancer activity of natural product Britanin was evaluated both in vitro and in vivo,and a nano-delivery system for Britanin that can target tumors was preliminarily constructed.Retrospective verification of RGD-HFn-Britanin will be the next goal.The current research results provide a promising candidate for chemotherapy towards gastric cancer,and efforts have been made to achieve improved drug efficacy and possible clinical transformation.