Studies On Multifunctional Nanoparticles Loading Doxorubicin And Tetrahydrocurcumin For Concurrent Chemoradiotherapy

Glioma is the most common and aggressive type of brain tumors with poor prognosis.Surgery,radiotherapy and chemotherapy are major treatments for glioma.However,glioma can rarely be cured with only chemotherapy or radiotherapy,largely due to limited drug penetration of blood-brain barrier,resistance to radiation and severe side effects.Recently,multifunctional nano-carriers have been developed for simultaneous delivery of radiosensitizers and chemotherapy drugs with tumor-targeting drug delivery and stimuli-sensitive drug release properties,which is a promising strategy to improve therapeutic efficiency of glioma.In the present work,the enhanced radiosensitizing effects of THC on glioma cells were examined for the first time,and its underlying mechanism was preliminarily explored.MTT assays,colony forming and wound healing assay were performed to detect the proliferation,radiosensitivity and migration of cells,respectively;Cell apoptosis,cell cycle and GHS level were determined for exploring potent sensitization mechanism of THC.Meanwhile,protein expressions of cyclin D1 and PCNA were also measured.As shown in the results,cells treated with combined THC and radiation demonstrated lower cell viability and higher apoptosis rate compared with radiation group.Moreover,the intracellular GSH was also decreased in the THC co-treated C6 cells;More importantly,combinational treatment group significantly induced G0/G1 cell cycle arrest and a decrease in the S phase cell through the down-regulation of cyclin D1 and PCNA.In conclusion,THC could synergistically enhance the radiosensitivity of glioma cells by inhibiting the expressions of cyclin D1 and PCNA.Then,transferrin-modified PEG-PLGA nanoparticles containing doxorubicin and tetrahydrocurcumin were developed for synergistic chemoradiotherapy of glioma using a double emulsion method.The morphologies of nanoparticles were examined by transmission electron microscopy;The particle size and zeta-potential of nanoparticles were determined by DLS;The in vitro release studies were also conducted;The cytotoxicity studies were performed using conventional MTT assays;Cellular uptake of various nanoparticles was analyzed using a fluorescence microscope;The tissue distribution and brain targeting properties of Tf-NPs were investigated by ex vivo DOX fluorescence imaging;The in vivo tumor growth inhibition was performed on both orthotopic C6 mouse models and C6 subcutaneously grafted mouse models.As shown in the results,when the copolymer/drug ratio was 15:1:1,the nanoparticles presented desirable drug loading content of 6.71%;The mean particle size of each formulation was around 250 nm with a polydispersity index of less than 0.3,indicating that the prepared nanoparticles were uniform.The nanoparticles exhibited a rapid drug release in acidic condition compared with that in pH 7.4,which led to targeted drug release;Tf-NPs-DOX-THC were found to significantly inhibit proliferation of rat C6 glioma cells in vitro;As compared with DOX-and THC-loaded PEG-PLGA nanoparticles(NPs-DOX-THC),Tf-targeted nanoparticles exhibited efficient cellular internalization by C6 cells and selective accumulation in brain in vivo;Furthermore,Tf-NPs-DOX-THC in combination with RAD achieved favorable antitumor efficacy in both orthotopic glioma nude mice and subcutaneous glioma nude mice.In conclusion,all these results suggested combination of Tf-NPs-DOX-THC and RAD was a novel and promising strategy for synergistic chemoradiotherapy of glioma.