Acta Pharmacologica Sinica (2010) 31: 73–80; doi: 10.1038/aps.2009.172; published online 7 December 2009

Yan-qiu OU^#, Wen bo ZHU^#, Yan LI^#, Peng-xin QIU, Yi-jun HUANG, Jun XIE, Song-min HE, Xiao-ke ZHENG, Tian-dong LENG, Dong XU, Guang-mei YAN*

Department of Pharmacology, Zhong-shan Medical College, Sun Yat-Sen University, Guangzhou 510089, China

Aim: To investigate whether aspirin is able to augment gemcitabine-induced cytotoxicity in human pancreatic cancer cells.

Methods: Two gemcitabine-insensitive human pancreatic cancer cell lines, PANC-1 and Capan-1, were used.  Cells were treated with either aspirin or gemcitabine alone or both of them.  Cell growth and apoptosis were determined by MTT assay, Annexin V or Hoechest 33258 staining.  Cell cycle distribution was examined by flow cytometry.  Western blot with specific phosphorylated protein antibodies was used to detect the activation of protein kinase.  RT-PCR and Western blot were applied to assess the transcription and protein level for cyclin D1 and Bcl-2.    

Results: Aspirin alone significantly inhibits the proliferation of PANC-1 cells by causing cell cycle arrest at G₁ phase.  Aspirin potentiates the anti-survival effect of gemcitabine as well as its pro-apoptotic effect in PANC-1 cells, although aspirin per se does not trigger apoptosis.  Aspirin inhibits GSK-3β activation and suppresses the expression of its downstream gene products (cyclin D1 and Bcl-2), which are implicated in proliferation, survival and chemoresistance of pancreatic cancer.  The effects of aspirin on Capan-1, were similar to that on PANC-1.

Conclusion: Our results suggest that aspirin inhibits the proliferation of gemcitabine-resistant pancreatic cancer cells and augments the antisurvival effect of gemcitabine, probably by suppressing the activity of GSK-3β and its downstream gene products.

Keywords: aspirin; human pancreatic cancer; gemcitabine; apoptosis; GSK-3β; cyclin D1; Bcl-2