A self-guidance biological hybrid drug delivery system driven by anaerobes to inhibit the proliferation and metastasis of colon cancer

Colorectal cancer is often accompanied by multiple organ metastasis.Anaerobic Bifidobacterium Infantis(BI)bacterial can selectively grow in hypoxic colorectal tumor microenvironment(TME),to own the natural advantage of preferentially colorectal tumor targeting.Herein,a self-guidance biological hybrid drug delivery system(BI-ES-Fe Alg/DOX)based on BI was constructed to inhibit the proliferation and metastasis of colon cancer.Results demonstrated that BI-ES-Fe Alg/DOX could overcome physical barriers to target and accumulate in colon tumor tissues.Then DOX was released to kill tumor cells along with the phase transition(solid to liquid)of Fe Alg hydrogel,due to Fe3+was reduced to Fe^(2+)by intracellular GSH.Meanwhile,BI-ES selectively colonized into tumors and expressed endostatin(ES)protein to down-regulate VEGF and b FGF expression,exerting anti-angiogenic effect.Moreover,Fe Alg catalyzed H_(2)O_(2)in the local tumor to generate cytotoxic·OH,further enhancing the antitumor effect.The pharmacodynamic result in AOM/DSS model proved that BI-ES-Fe Alg/DOX had the best therapeutic effect,with the final V/V0of 2.19±0.57,which was significantly lower than the other groups.Meanwhile,on CT-26tumor-bearing model,it also showed an outstanding anti-tumor effect with inhibition rate of 82.12%±3.08%.In addition,lung metastases decreased significantly in tumor metastasis model after BI-ES-Fe Alg/DOX treatment.

In situ autophagy regulation in synergy with phototherapy for breast cancer treatment

Autophagy is an important factor in reducing the efficacy of tumor phototherapy(including PTT and PDT).Accurate regulation of autophagy in tumor cells is a new strategy to improve the anti-tumor efficiency of PTT/PDT.This project intended to construct a tumor-activated autophagy regulator to efficiently block PTT/PDT-induced autophagy and realize synergistic sensitization to tumor phototherapy.To achieve this goal,we first synthesized TRANSFERRIN(Tf)biomimetic mineralized nano-tellurium(Tf-Te)as photosensitizer and then used disulfide bond reconstruction technology to induce Tf-Te self-assembly.The autophagy inhibitor hydroxychloroquine(HCQ)and iron ions carried by Tf were simultaneously loaded to prepare a tumor-responsive drug reservoir Tf-Te/HCQ.After entering breast cancer cells through the“self-guidance system”,Tf-Te/HCQ can generate hyperpyrexia and ROS under NIR laser irradiation,to efficiently induce PTT/PDT effect.Meanwhile,the disulfide bond broke down in response to GSH,and the nanoparticles disintegrated to release Fe2+and HCQ at fixed points.They simultaneously induce lysosomal alkalinization and increased osmotic pressure,effectively inhibit autophagy,and synergistically enhance the therapeutic effect of phototherapy.In vivo anti-tumor results have proved that the tumor inhibition rate of Tf-Te/HCQ can be as high as 88.6%on 4T1 tumor-bearing mice.This multifunctional drug delivery system might provide a new alternative for more precise and effective tumor phototherapy.