Construction Of Specific Chemo-photothermal Therapy Nanoparticles HCR NPs And Its Anti-colorectal Cancer Effect

Objective: Colorectal cancer(CRC)is a common malignancy with the second highest mortality and the third highest morbidity worldwide.Surgical treatment is currently the main and the first treatment means of colorectal cancer.Although it can alleviate the disease to a certain extent and delay the progress of disease,there are still many defects and problems.Therefore,it is of great clinical significance to develop new diagnosis and treatment methods and more safe and effective targeted drugs to inhibit the growth and progression of colorectal cancer.In this study,by constructing nano drugs targeting colorectal cancer,we explored their inhibitory effect on colorectal cancer and the mechanism of action,and provided a new clinical strategy for the treatment of colorectal cancer.Methods: Celastrol(CLT),a natural bioactive compound,has been reported to induce reactive oxygen species(ROS)-mediated apoptosis to exhibit significant antitumor effects against CRC.However,the poor water solubility,low targeting ability,and bioavailability of CLT have limited its application,and CLT-induced protective autophagy weakens its therapeutic efficiency.Photothermal therapy(PTT)is an attractive compliment to traditional cancer treatments owing to its unique advantages,such as noninvasiveness,low toxicity,negligible drug resistance,and minimal side effects.The new indocyanine green(IR820)as a photosensitizer,has been approved by the Food and Drug Administration(FDA)for clinical use,having the merits of strong near-infrared absorbance,excellent biocompatibility,and easy metabolism.We designed a targeted chemo-phototherapy nanoparticles(HCR NPs)to improve the application of CLT and antitumor effect.CLT and IR820 were self-assembled into nanoparticles,and then modified with hyaluronic acid(HA)-conjugated hydroxychloroquine(HCQ)to obtain the final HCR NPs.Moreover,MTT assay,Ed U assay,and apoptosis assay were used to evaluate the antitumor effect of HCR NPs in vitro.Additionally,a nude mouse xenograft model was used to evaluate the antitumor capacity of HCR NPs in vivo.Results: Through the measurement of diameters,zeta potential,UV absorption characteristic peak,and observation of morphology,the results showed that the preparation of nanoparticles was successful.At the same time,the in vitro photothermal capability showed that the nanoparticles had good heating capability.The anti-colorectal cancer properties of HCR NPs were examined by using 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide(MTT)assay,Ed U assay,LDH assay,colony formation,and other experiments.The results showed that the nanoparticles had a good inhibition on the proliferation and growth of tumor cells.The results of flow cytometry and western blotting showed that the nanoparticles could promote the apoptosis of tumor cells.The detection of reactive oxygen species(ROS)showed that nanoparticles could promote the accumulation of ROS in CRC cells.The expression of peroxiredoxin-2(PRDX2)was measured by western blotting assay.In other words,the expression of PRDX2 was inhibited by nanoparticles,which could promote ROS accumulation and apoptosis.A mouse xenograft tumor model was first established to perform in vivo assays.The biodistribution of HCR NPs was detected by living imaging system,and the results showed that mice injected with nanoparticles in the tail vein had significant nanoparticle enrichment at the tumor site.The in vivo photothermal capability showed that the nanoparticles had a good heating effect.The antitumor experiment showed that the nanoparticles had remarkable antitumor effect.Immunohistochemical and mouse blood biochemical tests showed that the nanoparticles had good biological safety.In summary,HCR NPs showed good inhibitory effect on the growth of colorectal cancer in vitro and in vivo.Conclusions: The codelivery of IR820 and CLT in HCR NPs solved the water-soluble problem of CLT and enhanced apoptosis via IR820-mediated hyperthermia.In addition,hydroxychloroquine(HCQ)conjugated to hyaluronic acid(HA)not only increased the active targeting of HCR NPs but also inhibited CLT-induced protective autophagy to exacerbate apoptosis.The HCR NPs exhibited an excellent antitumor effect on CRC both in vitro and in vivo.In addition,HCR NPs showed good biosafety and no significant damage to major organs,demonstrating its potential application in the treatment of colorectal cancer.The HCR NPs presented in this study may not merely provide a new reference for the clinical application of CLT but also result in an attractive strategy for CRC treatment.