Human Telomerase Reverse Transcriptase Gene Antisense Oligonucleotide Increases the Sensitivity of Pancreatic Cancer Cells to Gemcitabine In Vitro

Resistance to gemcitabine is the major problem in pancreatic cancer chemotherapy, and recent evidence suggests that down-regulation of hTERT mRNA could enhance the antitumor efficacy of other well known chemotherapy agents targeting DNA. The aim of this study was to evaluate the combined antitumor efficacy of antisense oligonucleotides (AS-ODN) targeting hTERT mRNA and gemcitabine in human pancreatic cancer cells. Our results showed that transient transfection in clones of the human pancreatic cancer cell lines BxPC-3 and Panc-1 with 0.2μM hTERT AS-ODN for 24 h diminished the abundance of hTERT mRNA and inhibited telomerase activity, but only resulted in a slightly attenuated ability of proliferation. While pretreatment with 0.2μM AS-ODN for 24 h followed by gemcitabine in BxPC-3 or Panc-1 cells led to tumor cell growth suppression more significantly than gemcitabine alone in MTT, and the IC50 of gemcitabine was reduced to about 8.7 times in Panc-1 cells, and 4.2 times in BxPC-3 cells. Likewise, after treatment with gemcitabine for 48 h, the AS-ODN-transfected cells exhibited significantly decreased colony formation ability relative to the parental cells. Apoptosis analysis indicated that hTERT AS-ODN increased the gemcitabine-induced apoptosis in both cell lines. All together, these findings implied that hTERT AS-ODN could increase the chemosensitivity of gemcitabine through down-regulation of hTERT mRNA expression and inhibition of telomerase activity, which may make it an attractive agent for the sensitization of pancreatic cancer cells to gemcitabine.