Construction Of Sparfloxacin Based Drug Delivery System And Application Of Triple Negative Breast Cancer Treatment

Background:Under the premise that breast cancer has become the number one cancer in the world,it is of great significance to inhibit the growth of breast cancer and improve the prognosis.Triple negative breast cancer（TNBC）,as one of the breast cancers with obvious invasive characteristics,needs improved research in this area,especially in anti-metastasis.Chemotherapy,as a conventional therapy,has a relatively common frequency of use and has made indelible contributions to the treatment of breast cancer.However,chemotherapy has different disadvantages,including rapid drug degradation and simultaneous eli mination from the system,poor bioavailability,and systemic toxicity due to non-specific targeting and biological distribution.In addition,because of the overexpression of the efflux pump,the enhancement of drug biotransformation,and the modification of target sites,cancer cells also showed resistance to chemotherapy.At this time,the vigorous development of nanotechnology has assisted in the next step of chemotherapy.Nanoparticles have unique properties,including enhanced bioavailability,improved internalization of tumor sites,site-specific delivery,anti-metastasis activity,and avoidance of multiple drug resistance.It can interact with chemotherapy,avoid the side effects of chemotherapy drugs,and improve the treatment efficiency.This article mainly focuses on an"old drug":sparfloxacin（SP）,which has been used clinically as an antibacterial drug for many years.However,due to its obvious phototoxicity,its application may be delisted.From the specific organic structure of its quinolone,SP has the same organic skeleton as anticancer quinoline agents,so it has a certain anti-tumor effect.Besides phototoxicity,it is safer in the human body.Objectives:The characteristics of drug SP include inhibition of nuclear type Ⅱ topoisomerase and chelation of intracellular metal ions,and influence of superoxide dismutase（SOD）and catalase（CAT）activities.Based on the above characteristics of SP,this paper will take advantage of the safety of SP and realize the fixed-point and quantitative release by constructing a specific drug release system,and improve the chemotherapy effect in combination with other therapies to achieve the treatment of TNBC and anti-lung metastasis effect.Methods:Part Ⅰ:Through the selection of amphiphilic thermosensitive polymers,SP and upconversion nanoparticles（UCNPs）were co-coated to form nanomicelles（labeled USP）to achieve tumor treatment and anti-metastasis effects.The successful synthesis of USP was verified by various characterization methods,and its structure and release properties were explored.At the cellular level,the endocytosis was investigated by Nile red labeling and biological transmission electron microscopy;The reactive oxygen species（ROS）production of USP under 980 nm near-infrared light irradiation,namely the phototoxicity of SP,was investigated by using ROS probe;Cell proliferation and apoptosis were investigated by measuring cell viability,live-death staining,and flow cytometry analysis;The migration and invasion of cells were investigated by scratch test,plate cloning test and cell invasion test;The changes of the concentration of SOD and CAT in cells were investigated through the SOD and CAT kit;The changes of apoptotic proteins were investigated by Western blot.On the animal level,the anti-tumor effect of USP in vivo was verified by establishing a subcutaneous tumor model of mouse breast cancer cells（4T1）;The anti-metastasis ability of USP was verified by establishing a lung metastasis model of tumor in situ;The mechanism of the anti-tumor effect and anti-metastasis ability of USP was explored through the detection of various cytokines.Part Ⅱ:Through the selection of hyaluronic acid（HA）microneedle system,zinc manganese sulfide,and SP are coated together（recorded as ZMS/SP-HA microneedle）to further improve the fixed point and quantitative release of SP in situ breast cancer,and achieve treatment and stronger anti-metastasis effect.The successful synthesis of ZMS/SP-HA microneedle was verified by various characterization methods,and its structure and mechanical properties were explored.In terms of bacteria,their antibacterial properties were investigated by plate coating dilution method and live-death staining.At the cellular level,the role of different fluorescent probes in breaking the redox equilibrium was explored;Cell proliferation and apoptosis were investigated by measuring cell viability,live-death staining,and flow cytometry analysis;The cell migration was investigated by scratch test;On the animal level,the mouse wound model was established to study its role in wound healing;The ability of anti-tumor and anti-metastasis was verified by establishing a lung metastasis model of tumor in situ.Results:Part Ⅰ:Under 980 nm laser irradiation,USP has the effect of treating TNBC and inhibiting lung metastasis.At the material level and the cell level,the endocytosis of USP and the production of ROS were verified.At the cellular level,USP has the effect of inhibiting cell proliferation,migration,and invasion,and enhancing apoptosis.At the animal level,it was verified that USP inhibited the growth and lung metastasis of breast cancer in mice.Part Ⅱ:ZMS/SP-HA micro-needle patch was successfully prepared and has good mechanical properties,has the effect of treating TNBC,and inhibits lung metastasis.In terms of bacteria,it has the excellent antibacterial ability to cope with possible postoperative infection.At the cellular level,based on the role of metal ions(Zn²⁺,Mn^2+/4+)and H₂S in promoting ROS production and SP and variable valence Mn^2+/4+in inhibiting the enzyme of reducing system,it is verified that it can break the oxidation-reduction equilibrium and inhibit cell proliferation and migration.On the animal level,it shows the ability to promote wound healing and anti-tumor.However,there are still some defects in immune activation and lung metastasis and its mechanism.Conclusions:A specific drug release system based on SP has been successfully constructed,including thermosensitive polymer micelles and microneedle patches,which can achieve fixed-point and quantitative release,ensure safety,and improve the effect of chemotherapy by combining the effects of near-infrared light to activate the phototoxicity of SP and ZMS/SP to break the oxidation-reduction balance,and achieve the therapeutic effect of TNBC and anti-lung metastasis.In conclusion,the drug release system provides a new strategy to help patients avoid the side effects of chemotherapy and improve their survival rate.