Small interfering RNA against the apurinic or apyrimidinic endonuclease enhances the sensitivity of human pancreatic cancer cells to gemcitabine in vitro.

OBJECTIVE: To investigate whether the downregulation of human apurinic or apyrimidinic endonuclease/redox factor-1 gene (APE1/Ref-1) expression by ribonucleic acid interference (RNAi) would increase the sensitivity of SW1990 cells to gemcitabine.

METHODS: Chemically synthesized small interfering RNA (siRNA) directed against human APE1/Ref-1 (si-APE1) was transfected into SW1990 cells through transfection reagents. The mRNA expression of APE1/Ref-1 was detected by semi-quantitative RT-PCR and the protein expression of APE1/Ref-1 was detected by Western blot; cell proliferation and apoptosis were studied by a Cell Counting Kit 8 (CCK-8) and flow cytometry (FCM) and fluorescence microscopy.

RESULTS: After transfecting the SW1990 cells with siRNA directed against human APE1/Ref-1, the mRNA expression of APE1/Ref-1 of these cells was reduced, and its protein expression was reduced by 55.41 +/- 3.58%. The CCK-8 assay showed that the absorbance and the inhibition of cell growth transfected with si-APE1 were significantly different from the blank (cultured with Dulbecco's modified Eagle's medium) and negative control (given 50 nmol/L scrambled control siRNA). The inhibition rates of cell growth of the si-APE1 group at 24, 48, 72 h were 41.69 +/- 2.78%, 24.83 +/- 3.70% and 21.27 +/- 9.82%, respectively. A FCM analysis and cell morphology study showed that the apoptotic rate of SW1990 cells transfected with si-APE1 combined with gemcitabine treatment was significantly different from the blank control and others.

CONCLUSION: To knock down APE1/Ref-1 gene expression may significantly sensitize the SW1990 cells to gemcitabine and enhance cell apoptosis.