Objectives: To clarify the inhibition of pancreatic cancer cells by interference with the hTR component of the telomerase reverse transcriptase enzymatic complex and evaluate susceptibility of antisense hTR pancreatic cancer cellsto chemotherapeutic reagents.
Methods: A 593 bp of full length hTR cDNA was subcloned into a mammalian expression vector pcDNA3.1(-) in antisense orientation to construct an antisense hTR expression plasmid. The plasmids were introduced into Pancl cells, a human pancreatic carcinoma cell line, by lipofectin, and G418-resistant stable transformants were expanded. Resulting stable clones were screened for the presence of hTR insert by PCR with T7 and BGH reverse primers located on the flanks of the multiclonal site of pcDNA3.1 vector. Cell growth rate, hTR expression, telomerase activity, and anchorage-independent growth property were analyzed. Finally, susceptibility of antisense hTR cellsto chemotherapeutic reagents was evaluated.
Results: Significant downregulation of endogenous hTR was evident in the antisense-hTR transformed cells, and telomerase activity was markedly decreased compared to control cells in standard TRAP assays. Furthermore, the proliferation and the anchorage-independent growth ability in antisense-hTR expressing cells were significantly decreased compared with the control parental cells. However, no crisis or senescence phenomena was observed. Antisense hTR appearsto increase Pancl cell’s susceptibility to chemotherapeutic reagent cDDP, but not to differentiation reagent DMSO, COX2 inhibitor sulinbac, NS-398, curcumin, and chemotherapeutic reagent adriamycin (ADM).
Conclusions: These data indicate that hTR is probably a critical component of human telomerase activity and that downregulation of the RNA component of human telomerase is an effective target for anticancer strategy and antisense hTR can increase Pancl cell’s susceptibility to cDDP.