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@#[Abstract] Objective: To explore the application value of human IL-15 transgenic NCG mice (NCG-hIL-15 mice) in preclinical evaluation of chimeric antigen receptor modified NK (CAR-NK) cell therapy for tumor treatment. Methods: qPCR and WB were performed to detect the expression of human IL-15 in the bone marrow and main organs (spleen, liver, lung, kidney and pancreas) of transgenic mice. After being transfused with human PBMC-derived NK (PB-NK) cells, the NCG-hIL-15 mice and control NCG mice were continuously monitored for the in vivo amplification of NK cells and the changes in body weight and survival time. Flow cytometry was used to detect the differential expressions of activated receptors and inhibitory receptors in amplified NK cells. WB was used to detect the expressions of perforin and granzyme-B. NCG-hIL-15 mice or NCG mice bearing MIAPaca-2 cell transplanted tumor were treated with anti-MUC1-CAR-NK cell reinfusion; then, the CAR-NK cell survival in different groups of mice was detected by Flow cytometry, and the survival time of tumor bearing mice was recorded and tumor growth was detected by in vivo imaging. Results: The results indicated that PB-NK cells could proliferate stably within 10 weeks in NCG-hIL-15 mice without obvious graft versus host diseases (GVHD) during the observation period. The in vivo-expanded human NK cells maintained the original expression patterns of various surface molecules, including KARs and KIRs. Compared with the NK cells in NCG mice, the NK cells in NCG-hIL-15 mice contained significantly higher amounts of granzyme-B and perforin (all P<0.05). CAR-NK cells showed significantly increased survival rate and stronger tumor-inhibitory effect in NCG-hIL-15 mice as compared with those in control NCG mice, resulting in significantly prolonged survival in NCG-hIL-15 mice (all P<0.01). Conclusion: NCG-hIL-15 mouse model has potential application value in preclinical trial and biological evaluation of NK cell-based immunotherapy.
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@# Objective: To investigate the effects and the underlying mechanisms of betulinic acid (BEA) on sensitizing pancreatic cancer cell lines Panc-1 and Miapaca-2 to gefitinib. Methods: After the cell culture was completed, Panc-1 and Miapaca-2 cells were randomly divided into 4 groups: control group (without treatment), BEAgroup, gefitinib group and BEAcombined with gefitinib group, respectively.The sensitization effect of BEAon gefitinib-insensitive pancreatic cancer cells was detected by MTS assay. The treatment effects of combined treatment of gefitinib and BEA against Panc-1 and Miapaca-2 cells were evaluated by colony formation assay. Flow cytometry was used to examine the effect of BEAon apoptosis of Panc-1 cells while WB was applied to determine the effect of BEAonapoptosis-related proteins. Surface plasmon resonance (SPR) experiment was used to detect the direct combination between signal transducer and activator of transcription 3(STAT3) and BEA; Molecular docking and molecular dynamics simulation experiments were adopted topredict the combining mode between STAT3 and BEA. Results: BEA synergistically enhanced the gefitinib-sensitivity of pancreatic cancer Panc-1 and Miapaca-2 cells (P<0.05), and IC50 of gefitinib on two cells were reduced by over 50%. Compared with single treatment, the combined treatment of BEA and gefitinib promoted the apoptosis and up-regulated the expressions of apoptosis-relatedproteins (cleaved-PARP and Bax), but reduced the apoptosis-inhibitory protein Bcl-2 (all P<0.05 or P<0.01). Moreover, the inhibitory effect of BEA on STAT3 activation in Panc-1 cells was in a dose-dependent mannar (P<0.01). BEA stabilizes its binding to STAT3 by forming hydrogen bonds with Lys-591 and Ser-613 of STAT3; in the meanwhile, BEA stabilized inthebinding site of STAT3, there by blocking STAT3 dimerization to enhance the drug sensitivity. Conclusion: Combined use of BEA and gefitinib could significantly inhibit the proliferation and induce apoptosis of Panc-1 and Miapaca-2 cells, which might be mediated by the inhibition of BEA on STST3.