Enhancing The Efficacy Of Doxorubicin By SiMCT1 Delivery With Cationic Lipid Assisted Nanoparticle

Malignant tumor is an important disease seriously threatening human health.Chemotherapy is the most important systemic treatment means,but it lacks specificity and is prone to cause systemic adverse reactions,the combination of chemotherapy and other therapies is the trend of tumor treatment.Monocarboxylic acid transporter 1（MCT1）mediates the bidirectional transport of lactic acid efflux and reuptake in tumor cells,several studies have confirmed that interfering with MCT1 function can effectively inhibit the growth and metastasis of various types of tumor.RNA interference（RNAi）has the theoretical ability to down-regulate the expression of any gene,showing great advantages in the treatment of malignant tumors.However,siRNA is easy to be degraded by nuclease and difficult to enter target cells,which limits its wide application.Nanocarriers have the ability to help siRNA overcome delivery barriers and improve the efficiency of siRNA action,which has an important application in the field of RNAi technology for disease treatment,Our lab has developed a Cationic Lipid-Assisted Nanoparticle（CLAN）,which can effectively improve the load of siRNA,overcome the difficulties of siRNA delivery in vivo,it’s very effective in a variety of disease.This paper aims to combine the advantages of MCT1 in promoting tumor metastasis and RNAi therapy in tumor treatment,to explore the effect of CLAN delivery of MCT1-targeting siRNA（siMCT1）in combination with chemotherapy drug doxorubicin（DOX）to inhibit tumor proliferation and metastasis,the main contents and results are as follows:In the first part of this study,using polyethylene glycol-polylactic acid(PEG_5K-b-PLAG_10.5K)as the main material,with 8%（W/W）cationic lipid（2,3-dioleyl-propyl）-trimethylammonium chloride（DOTAP）and 0.8%（W/W）siRNA,CLAN_siMCT1 nanoparticles prepared by double emulsification.The particle size of the nanoparticles was 113±2.01 nm,the PDI was 0.161,and the encapsulation rate was 96.77%,it has good stability,by flow cytometry（FCM）and Real-Time quantitative PCR（RT-q PCR）,we found that CLAN could effectively deliver siRNA into mouse melanoma cell B16F10 and effectively knock down the expression of MCT1.The lung metastasis of B16F10 cells was effectively affected,but the proliferation of B16F10 cells was not inhibited.In the second part,in order to achieve the purpose of simultaneously killing tumor cells and inhibiting tumor cell metastasis,we’re using CLAN_siMCT1 in combination with DOX to study its anti-tumor efficacy.It was found that reducing MCT1 expression enhanced the sensitivity of B16F10 cells to DOX,and the combination therapy significantly inhibited tumor growth in mice loaded with B16F10 subcutaneous tumor model,RT-q PCR and Western Blotting（WB）proved that CLAN_siMCT1 can effectively down-regulate the expression of MCT1 in tumor tissues.H&E staining and blood biochemical analysis of the main organs of mice showed that there was no pathological damage in the main organs of mice in each group,and the main biochemical function index values were within the normal range,These results suggest that combining CLAN_siMCT1 and DOX is a potential cancer treatment strategy.