γ-Secretase inhibitor DAPT sensitizes t-AUCB-induced apoptosis of human glioblastoma cells in vitro via blocking the p38 MAPK/MAPKAPK2/Hsp27 pathway
Abstract
Jun-yang LI1, Ru-jun LI2, Han-dong WANG1, *
1Department of Neurosurgery, Jinling Hospital, School of Medicine, Nanjing University, Nanjing 210002, China; 2Department of Neurosurgery, Second Affiliated Hospital of Soochow University, Suzhou 215004, China
Aim: Trans-4-[4-(3-adamantan-1-yl-ureido)-cyclohexyloxy]-benzoic acid (t-AUCB) is a soluble epoxide hydrolase inhibitor that suppresses glioblastoma cell growth in vitro. The aim of this study was to examine whether the γ-secretase inhibitor N-[N-(3,5-difluorophenacetyl)-l-alanyl]-S-phenylglycine t-butyl ester (DAPT) could sensitize glioma cells to t-AUCB-induced apoptosis.
Methods: Both U251 and U87 human glioblastoma cell lines were tested. Cell growth was assessed using the cell counting kit-8. Cell apoptosis was detected with caspase-3 activity assay kits and flow cytometry. The protein levels in the p38 MAPK/MAPKAPK2/Hsp27 pathway in the cells were analyzed using Western blots.
Results: Pretreatment with DAPT (2 μmol/L) substantially potentiated the growth inhibition caused by t-AUCB (200 μmol/L) in U251 and U87 cells. Furthermore, pretreatment with DAPT markedly increased t-AUCB-induced apoptosis of U251 and U87 cells. T-AUCB alone did not significant affect caspase-3 activity in the cells, but t-AUCB plus DAPT pretreatment caused significant increase of caspase-3 activity. Furthermore, pretreatment with DAPT completely blocked t-AUCB-induced phosphorylation of p38 MAPK, MAPKAPK2 and Hsp27 in the cells.
Conclusion: The γ-secretase inhibitor DAPT sensitizes t-AUCB-induced apoptosis of human glioblastoma cells in vitro via blocking the p38 MAPK/MAPKAPK2/Hsp27 pathway, suggesting that the combination of t-AUCB and DAPT may be a potentially effective strategy for the treatment of glioblastoma.
Keywords: glioma; chemotherapy; γ-secretase; DAPT; soluble epoxide hydrolase; t-AUCB; apoptosis; caspase-3; p38 MAPK; MAPKAPK2; Hsp27
We thank Prof Bruce D HAMMOCK for providing the sEH inhibitor t-AUCB. This study was supported by the National Natural Science Foundation of China (No 81070974 and No 81301905).
* To whom correspondence should be addressed.
E-mail njhdwang@hotmail.com
Received 2013-09-24 Accepted 2013-12-12
Keywords:
1Department of Neurosurgery, Jinling Hospital, School of Medicine, Nanjing University, Nanjing 210002, China; 2Department of Neurosurgery, Second Affiliated Hospital of Soochow University, Suzhou 215004, China
Aim: Trans-4-[4-(3-adamantan-1-yl-ureido)-cyclohexyloxy]-benzoic acid (t-AUCB) is a soluble epoxide hydrolase inhibitor that suppresses glioblastoma cell growth in vitro. The aim of this study was to examine whether the γ-secretase inhibitor N-[N-(3,5-difluorophenacetyl)-l-alanyl]-S-phenylglycine t-butyl ester (DAPT) could sensitize glioma cells to t-AUCB-induced apoptosis.
Methods: Both U251 and U87 human glioblastoma cell lines were tested. Cell growth was assessed using the cell counting kit-8. Cell apoptosis was detected with caspase-3 activity assay kits and flow cytometry. The protein levels in the p38 MAPK/MAPKAPK2/Hsp27 pathway in the cells were analyzed using Western blots.
Results: Pretreatment with DAPT (2 μmol/L) substantially potentiated the growth inhibition caused by t-AUCB (200 μmol/L) in U251 and U87 cells. Furthermore, pretreatment with DAPT markedly increased t-AUCB-induced apoptosis of U251 and U87 cells. T-AUCB alone did not significant affect caspase-3 activity in the cells, but t-AUCB plus DAPT pretreatment caused significant increase of caspase-3 activity. Furthermore, pretreatment with DAPT completely blocked t-AUCB-induced phosphorylation of p38 MAPK, MAPKAPK2 and Hsp27 in the cells.
Conclusion: The γ-secretase inhibitor DAPT sensitizes t-AUCB-induced apoptosis of human glioblastoma cells in vitro via blocking the p38 MAPK/MAPKAPK2/Hsp27 pathway, suggesting that the combination of t-AUCB and DAPT may be a potentially effective strategy for the treatment of glioblastoma.
Keywords: glioma; chemotherapy; γ-secretase; DAPT; soluble epoxide hydrolase; t-AUCB; apoptosis; caspase-3; p38 MAPK; MAPKAPK2; Hsp27
We thank Prof Bruce D HAMMOCK for providing the sEH inhibitor t-AUCB. This study was supported by the National Natural Science Foundation of China (No 81070974 and No 81301905).
* To whom correspondence should be addressed.
E-mail njhdwang@hotmail.com
Received 2013-09-24 Accepted 2013-12-12