Mutually Synergistic Nanoparticles For Thermo-molecularly Targeted Cancer Therapy

Photothermal therapy(PTT)for tumor ablation has attracted extensive attentions around the world in recent years.The photothermal agent delivered into the tumor site is able to produce heat(over 42 ?)under the irradiation,leading to acute necrosis,apoptosis and immune reaction of tumor cells,thereby achieving tumor elimination.However,tumors treated with PTT are prone to relapse due to the thermoresistance and insufficient damage of tumor cells.Therefore,how to overcome the thermoresistance and improve the PTT efficacy is a hot topic in cancer treatment.Indeed,it is reported that heat shock proteins(HSPs)such as HSP90 will be overexpressed in response to hyperthermia to protect the tumor cells from the heat damage.The inhibition of HSPs can improve the efficacy of PTT.Meanwhile,the inhibitors of HSPs also play a significant role in molecular targeted therapy(MTT).Objective:To achieve the synergistic effect of PTT and MTT,the polymeric micelles loaded with 17AAG,an inhibitor of HSP90,and Cypate,a near-infrared flurescent dye,were constructed.And we further explore the synergistic effect of PTT of Cypate and MTT exerted by 17AAG against tumor.Methods:(1)PEG115-PCL60 was used as the polymer to load Cypate and HSP90,and the synergistic micelles(CA-Micelles)were constructed by dialysis method.The characteristics of CA-Micelles were investigated by TEM,while the release behavior of CA-Micelles was determined in various solutions.(2)A549 cells were utilized as the tumor cells to investigate the cellular uptake of CA-Micelles and its cytotoxicity.(3)The apoptosis of A549 cells and the expression of related proteins were examined by flow cytometry and gel electrophoresis,respectively.(4)A549 tumor-bearing mice were estabilished for animal study of CA-Micelles.Fluorescence imaging of Cypate was used to investigate the tumor targeting of CA-Micelles,and photothermal and photodynamic effects at the animal level were verified by photothermal imaging and DHE staining,respectively.(5)Subcutaneous tumor model was established to study the antitumor efficacy of CA-Micelles.Results:(1)Self-assembled micelles containing Cypate and 17AAG were successfully constructed.The micelles show a particle size of 60 + 10 nm with uniform size distribution.Drug loadings of Cypate and 17AAG in micelles are 14.6%and 1.6%,respectively.And the micellar entrapment can significantly increase the photothermal conversion efficiency of Cypate,thereby enhancing PTT effect.In addition,CA-Micelles show enhanced release of 17AAG at pH 5.0.(2)CA-Micelle can facilitate uptake of Cypate and 17AAG via a clathrin-mediated endocytosis pathway.The loaded Cypate would produce heat and singlet oxygen under irradiation,which could make lysosomal membrane rupture,and thus help 17AAG transport to the cytoplasm.(3)Western blot results showed that HSP90 was over-expressed in the tumor cells after treated with hyperthermia.However,17AAG could inhibit HSP90 to sensitize the tumor cells to photothemal effect.Meanwhile,the inhibition of intrinsic HSP90 leads to MTT effect,thus achieving PTT/MTT synergistic tumor ablation.(4)In vivo imaging results showed that CA-Micelles had good tumor-targeting ability.Furthermore,CA-Micelles exhibited good photothermal and photodynamic effect at the animal level.(5)Finally,CA-Micelles could produce synergistic antitumor effect via PTT and MTT without damaging surrounding normal tissues.Conclusions:The preparation of CA-Micelles was achieved using a simple and reproducible method.The micelles show a good tumor-targeting ability and exhibit synergistic anticancer effect via PTT and MTT at animal models bearing tumors.As a result,CA-Micelles provide a useful strategy to construct a promising nanomedicine for cancer therapy.