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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.
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@# Objective: To explore the mechanism of miR-429 targeting PTEN to affect capecitabine-resistance in pancreatic cancer PANC-1 cells though the PI3K/AKT signaling pathway. Methods: Capecitabine-resistant pancreatic cancer cell line PANC-1/CAP was constructed, and the expression of miR-429 and PTEN were detected by quantitative Real-time polymerase chain reaction (qRT-PCR) and Western blotting. The effect of miR-429 knock-down on cell proliferation viability, apoptosis and capecitabine-resistance was measured by colony formation assay, CCK-8 assay andAnnexin V-FITC/PI double staining flow cytometry assay, respectively. Subsequently, dual luciferase reporter assay verified that PTEN was a target gene of miR-429. Furthermore, the effect of miR-429 on PTEN-PI3K/ AKT signaling pathway was measured by Western blotting. Results: miR-429 was found to be up-regulated in PANC-1 cells and PANC-1/CAP cells compared with the non-malignant pancreatic ductal cell line (HPDE6-C7) (P<0.05 or P<0.01). Moreover, silencing of miR-429 significantly decreased cell proliferation viability, capecitabine-resistance and enhanced apoptosis of PANC-1/CAP cells; additionally, dual luciferase reporter assay confirmed that PTEN was a target of miR-429 (P<0.05 or P<0.01). Suppression of miR-429 up-regulated PTEN and blocked the PI3K/AKT signaling pathway to decrease cell proliferation viability and further reduce the capecitabine-resistance of PANC-1/CAP cells (P<0.05 or P<0.01). Conclusion: miR-429/PTEN-PI3K/AKT signaling pathway plays a certain role in regulating the capecitabine-resistance of pancreatic cancer, and inhibition of miR-429 expression may reverse the resistance of PANC-1/CAPto capecitabine.
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Objective Few reports are seen on the methods of establishing the rabbit model of pancreatic cancer .This study was to compare the effect of Panc-1 cell suspension orthotopic implantation with that of VX-2 tissue orthotopic implantation in construc-ting the rabbit model of pancreatic cancer . Methods Using the random number table method , we divided 30 healthy rabbits into a tissue suspension group ( n=15) and a cell suspension group ( n=15) , VX-2 tissue suspension employed for in-situ implanting in the former group and panc-1 cell suspension utilized in the latter .Then we evaluated the two modeling methods by B-ultrasonography , 3.0T MRI, and CT. Results In the third week after modeling , transpla-ntive metastasis of lots of tumor tissues was observed in the duode-num, colon, appendix, and peritoneal wall in 5 rabbits of the tissue suspension group , but only in the greater omentum of 3 rabbits in the cell suspension group , with high signals of MR T 2 in the posterior gastric body .One case of duodenal metastasis was seen in the cell suspension group , with slightly high signals of MR LAVA in the posterior gastric body .The model of pancreatic cancer was successfully established in all the 15 rabbits of the tissue suspension group , but only in 3 of the cell suspension group .The success rate of tumor im-planting at 3 and 4 weeks was significantly higher in the former ( 46.66%and 100%) than in the latter group ( 6.67%and 20.00%) (P<0.05). Conclusion VX-2 tissue orthotopic implantation is a more feasible and convenient method than Panc -1 cell suspension orthotopic implantation for establishing the rabbit model of pancreatic cancer .
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Objective: To clarify the structure features of polysaccharides from Chrysanthemum morifolium (PCM) and to study their activities against tumor cells and NF-κB. Methods: Six homogeneous neutral polysaccharides were obtained from three kinds of C. morifolium (Hangju, Huaiju, and Boju) flowers by successive hot water extraction, followed by ethanol precipitation, ion-exchange chromatography, and gel permeation chromatography. Their primary structures were characterized by HPGPC, IR, GC, and GC-MS analyses. Their bioactivities were examined by MTT assay using PANC-1 and LO2 cells. In addition, NF-κB signaling activation in PANC-1 and LO2 cells treated by polysaccharides were also measured. Results: The weight-average molecular mass of the six PCM, CMTA0S1, CMTA0S3, CMJA0S1, CMJA0S2, CMBA0S1, and CMBA0S3 was 7.523 × 104, 7.80 × 103, 7.80 × 104, 1.04 × 104, 5.79 × 104, and 1.35 × 104, respectively. CMTA0S1, CMJA0S1, and CMBA0S1 mainly contained galactose (Gal), arabinose (Ara) and glucose (Glc) residues in molar ratio of 1.23:1.00:0.20, 2.18:1.00:0.53, and 3.30:1.00:0.75, while CMTA0S3, CMJA0S2, and CMBA0S3 mainly contained Gal, Ara, Glc, and mannose (Man) residues in molar ratio of 0.73:1.00:0.40:0.21, 1.39:1.00:0.84: 0.55, and 1.19:1.00:0.48:0.19. Methylation analysis indicated that six PCM primarily consisted of T-arabinofuranosyl, 1, 5-arabinofuranosyl, 1, 4-galactopyranosyl, 1, 3, 6-galactopyranosyl, and 1, 4-glucopyranosyl residues. The biological activity study suggested that all the PCM could inhibit the growth of PANC-1 cells. Among them the inhibitory rates of CMTA0S3 and CMJA0S2 were at most to 70% with concentration-effect relationship. The NF-κB inhibition test indicated that only the crude polysaccharide CMBA had strong immunosuppressive activity, and homogeneous polysaccharides CMTA0S1 and CMJA0S1 showed potential immunostimulation. Conclusion: The six homogeneous polysaccharides share similar structures and inhibition on PANC-1 cells growth. Meanwhile they also may regulate the NF-κB activation.