Study On Doxorubicin-polyglycerol-nanodiamond Conjugates For Therapeutic Intervention Of Glioblastoma

Background: Glioblastoma(GBM)is the most common and malignant primary brain tumor and overall responds poorly to chemotherapy.Ineffective drugs for example doxorubicin(DOX)owing to the blood-brain barrier and abnormal tumor vascular distribution is a major cause of GBM's resistance to therapy.So we designed the device based on nanodiamonds with a surface coating of polyglycerol loaded with DOX which named Nano-doxorubicin(Nano-DOX).Astrocytes could promote the growth of GBM,But the mechanism was not clear.Most important is the mechanism of the function of Nano-DOX in astrocytes and GBM crosstalk needs further study.At the same time,Comparing the anti-tumor mechanisms of these two different forms of DOX is also a problem that we need to solve urgently.Objective:(1)Building the model of astrocytes and GBM crosstalk in vivo and vitro;Exploring the new mechanism of that astrocytes promoted the growth of GBM;Revealing the function of Nano-DOX in astrocytes and GBM crosstalk.(2)To compare the different mechanisms of Nano-DOX and DOX on glioma.Method:(1)The effect of astrocytes on proliferation,migration and apoptosis of glioma was studied by co-cultured with astrocytes and glioma cells;When Nano-DOX was added in co-cultured system,using Western blot,ELISA and RT-PCR technologies to detect the mechanism of the function of Nano-DOX in astrocytes and GBM crosstalk.(2)Autophagy,apoptosis-related proteins and HMGB1 were detected by flow cytometry,Western blot,ELISA and electron microscopy and compared the different mechanisms of Nano-DOX and DOX on glioma.(3)At last we used the immunodeficient mice to build the orthotopic GC xenograft modle to verify the mechanism of Nano-DOX inhibiting glioma by IL-6 /STAT3 signal and the special mechanism of Nano-DOX acting alone on glioma in vivo.Results:(1)Nano-DOX blocked the interaction between the GBM and astrocytes;Nano-DOX blocked IL-6/STAT3 signaling-mediated reciprocal activation between the GBM and astrocytes;Nano-DOX inhibited IL-6/STAT3 signaling activation in orthodox GBM xenografts in mice.(2)DOX induced apoptosis in GC while Nano-DOX induced autophagy and autophagy inhibition promoted apoptosis in Nano-DOX-treated GC.DOX suppressed the emission of HMGB1 while Nano-DOX stimulated HMGB1 emission which was attenuated when autophagy was repressed.Blocking of HMGB1 emission mitigated autophagy and enhanced apoptosis inNano-DOX-treated GC.Exogenously administered HMGB1 promoted autophagy and protected against apoptosis in both Nano-DOX-treated GC and DOX-treated GC.Conclusion: Nano-DOX inhibited the IL-6 of GBM and thereby blocked IL-6/STAT3 signaling-mediated reciprocal activation between the GBM and astrocytes;At the same time,Nano-DOX initiates a mutual reinforcement loop between autophagy and HMGB1 in GBM and thereby protects GBM against apoptosis.This study provides a new idea for regulating the GBM microenvironment and the treatment of GBM.