Preliminary Research On Radioresistance Of The Host-derived Malignant Transformed Cells In Tumor Stroma Induced By Glioma Stem Progenitor Cells

Objective：To establish red-green dual-color fluorescence tracing glioma model andexplore its actual practical values.Methods：C6-CM-DiI cells were transplanted into the brain of athymic nude miceexpressing green fluorescence protein (NC-C57BL/6J-EGFP). Then the dual-color tracingwith whole-body in-vivo fluorescence imaging was detected dynamically. Finally brains oftumor-bearing mice were removed completely and then5μm thick serial frozen sliceswere made. Light microscope, fluorescence microscopic and confocal laser scanningmicroscopy were performed to observe transplantation tumor organization structure andfluorescent cells.Results：The tumor with red fluorescence gradually increased under continuousin-vivo fluorescence imaging monitoring. Under the fluorescence microscope, cells withred, green and yellow fluorescence were observed in transplantation tumor tissue andmutual structural relationships among them could be defined. Also the tumor cellsmigration, implantation and cell fusion degree between transplantable tumor cells and hostcells could be observed. Furthermore according to the fluorescence tumor blood vesselscould be easily attributed: blood vessels originated from tumor itself displayed redfluorescence; blood vessels derived from host displayed green fluorescence and mosaicblood vessels appeared yellow fluorescence. We newly discovered that host innateastrocytes and oligodendrocytes in the microenvironment at the periphery of tumor couldbe activated and dedifferentiated to Nestin positive cells.Conclusion：In contrast to traditional animal model, the dual-color fluorescence tracing glioma model possessed enormous advantages in investigating tumor mass in-vivofluorescence imaging, tumor cells migration and metastasis, tumor angiogenesis andreactive activation of host innate cells in the microenvironment at the periphery of tumor. Objective: Glioma stem progenitor cells could induce malignant transformation ofthe host-derived cells in glioma stroma, however whether these malignant cells wereresistant to radiation as glioma stem progenitor cells was still unknown. The molecularmechanisms underlying radioresistance of these cells deserved further investigation.Methods: The SU3-5R cells were the progeny of SU3cells that had been irradiatedwith4Gy X-rays for5times to induce its radioresistance. Clonogenic assays wereperformed to assess the radiosensitivity of SU3, SU3-5R and ihBTC2(transformed hostglial cells induced by SU3), and the multi-target single-hit model was used to fit thesurvival curve. Quantitative Real Time-PCR was used to determine the relative mRNAlevels of Notch1and Hes1. pAkt and Bcl-2protein levels were assayed by Western blot.Results: The host interstitial malignant transformed cells, ihBTC2, was moreradioresistant than SU3-5R. Proliferation of these cells was accelerated after radiation invitro, radiation could upregulate pAkt activity and Bcl-2expression levels in ihBTC2cells.Notch inhibition with GSIs could sensitize radiation sensitivity of ihBTC2cells.Conclusion: Notch signaling could be involved in radioresistance of ihBTC2cells,which offered valuable references for further research on the role of tumor interstitialcomponents in tumor radioresistance.