Louis, MO); then, a secondary horseradish peroxidase (HRP)-conjugate antibody was utilized for immunodetection. of U87-EGFRvIII and has a better antitumor effect on 188Re-U2 and have a better antitumor effect of 188Re-U2. Our results revealed the encouraging potential of U2 to be a new type of drug candidate for glioblastoma therapy. In the current study, we investigated whether U2 treatment might impact the proliferation, migration, invasion, and apoptosis of U87-EGFRvIII cells and the involvement of relevant signaling pathways. Furthermore, we examined whether the U2 aptamer can increase the radiosensitivity of U87-EGFRvIII cells and improve the antitumor effect of 188Re-U2. Our findings revealed the encouraging potential of U2 to be 20-HETE a new type of drug candidate for glioma therapy. Results U2 Specifically Binds to the U87-EGFRvIII Cells U2 is usually a DNA aptamer obtained by cell SELEX technology using U87-EGFRvIII cells. To investigate the specificity of U2 for the different glioblastoma cells, including U87MG, U87-EGFRwt, and U87-EGFRvIII cells, we applied an FCM binding assay using the 5?end FAM-labeled U2 aptamers, and the FAM-labeled original library GN was used as a control. According to the FCM findings, FAM-U2 was bound to U87-EGFRvIII at a higher extent than FAM-GN bound to U87-EGFRvIII, whereas FAM-U2 shows no different significant binding to FAM-GN in U87MG and U87-EGFRwt cells (Physique?1). U2 binding to U87-EGFRvIII cells but 20-HETE not to U87-EGFRwt cells or U87MG cells confirmed its specificity for U87-EGFRvIII cells. Besides, we added other four main GBM cell lines to confirm the specificity of U2 and the results showed that the average rate of aptamer U2 binding to the four cell lines is usually less than 3% (Physique?S1A). Open in a separate window Physique?1 The Binding Relatives of FAM-U2 or FAM-GN with U87MG cells, U87-EGFRwt cells, and U87-EGFRvIII Cells Obtained by Circulation Cytometry U87MG cells, U87-EGFRwt cells, 20-HETE and U87-EGFRvIII cells bind with FAM-U2 and FAM-GN detected by flow cytometry. ***p? 0.001. Subcellular Localization of U2 Aptamer Consistent with the results by FCM, confocal microscopy on U87EGFRvIII cells with FAM-labeled U2 showed that cells with FAM-labeled aptamer for 5?min were combined with staining via a specific EGFR antibody (targeting to the extracellular EGFR domain name). A wide overlap of EGFR antibody and FAM-U2 fluorescent signals was detected around the membrane, indicating obvious co-localization of the aptamer and 20-HETE antibody around the receptor expressed around the cell surface (Physique?2A). Due to the phenomenon of FAM-U2 incubation after 20?min, overlap signals appeared in the cell and the next objective was BMP13 to validate the uptake mechanism for an anti-EGFR-aptamer complex. Consistently, after co-localization experiments of FAM-U2 with endocytosis markers, early endosome antigen 1 (EEA1) was confirmed by using z stack processing. After incubation for 30?min and then fixing and staining with anti-EGFR antibody and anti-EEA1 antibody, FAM-U2 and EGFR were co-localized inside the cells (Physique?2B), suggesting that U87EGFRvIII cells internalize the compounds through the endosome recycling pathway. Open in a separate window Physique?2 U2 Can Internalize into U87-EGFRvIII Cells (A) U87-EGFRvIII cells were treated with 2?M FAM-U2 for 5 and 20?min. Cells were fixed and labeled with anti-EGFR antibody targeting around the cell membrane without permeabilization. Green: fluorescence labeling FAM-U2; blue: cell nucleus (staining by DAPI); reddish: anti-EGFR antibody. (B) Z stack of U87-EGFRvIII cells incubated with 2?M FAM-U2 for 30?min. Level bar, 10?m. Cells were fixed, permeabilized, and labeled with anti-EGFR and anti-EEA1 antibodies. Green:.