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Archive > Volume 26 Issue 9 > 2019,26(9):948-954. DOI:10.3872/j.issn.1007-385X.2019.09.003 Prev Next
Basic Research
Betulinic acid enhances gefitinib-sensitivity of pancreatic cancer cells via inhibition of STAT3 activation
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Abstract:
[Abstract] 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), BEA group, gefitinib group and BEA combined with gefitinib group, respectively.The sensitization effect of BEA on 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 BEA on apoptosis of Panc-1 cells while WB was applied to determine the effect of BEA onapoptosis-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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