Abstract: Objective To investigate the effects of long-and short-isoform of doublecortin-like kinase 1 (DCLK1) on the proliferation of human pancreatic cancer and further to explore the molecular mechanism. Methods The control (PCMV6-AC-GFP), DCLK1 isoform 1 and DCLK1 isoform 4 eukaryotic expression plasmids were transfected into pancreatic cancer PANC-1 cells. G418 screening method was used to construct stable cell lines overexpressing long-and short-isoform of DCLK1. Expression of long-and short-isoform of DCLK1 were determined by quantitative real time polymerase chain reaction(qRT-PCR) and Western blotting. The effect of long-and short-isoform of DCLK1 on the proliferation of PANC-1 cells were detected with real-time cell analysis (RTCA) technology. The effect of DCLK1 on mitogen-activated protein kinase (MAPK) pathway was detected with Western blotting. DCLK1 stabilizing cells were treated with specific c-Jun N-terminal kinase (JNK) pathway inhibitor SP600125 to detect the effect of JNK pathway inhibition on the proliferation of pancreatic cancer cells. Results Overexpression of long-and short-isoform of DCLK1 remarkably promoted the proliferation of pancreatic cancer cells (P<0.05), increased the phosphorylation of JNK in MAPK pathway and the expression of target molecules CMYC, CD44 and CyclinD1 in JNK pathway (P<0.05). No significant influence on the phosphorylation of ERK and p38 were detected (P>0.05). SP600125 inhibited the phosphorylation of JNK and markedly decreased the activation of JNK pathway and the proliferation of pancreatic cancer cells by DCLK1 (P<0.05). Conclusion Both long-and short-isoform of DCLK1 promote the proliferation of pancreatic cancer cells via activating JNK pathway.

Key words: pancreatic cancer, doublecortin-like kinase 1 long and short isoforms, proliferation, JNK pathway