Up-regulation of Glycolysis Promotes the Stemness and EMT Phenotypes in Gemcitabine-resistant Pancreatic Cancer Cells

Cancer stem cells (CSCs) and epithelial-mesenchymal transition (EMT)-type cells are considered as underlying causes of chemoresistance, tumour recurrence and metastasis in pancreatic cancer. We aimed to describe the mechanisms - particularly glycolysis - involved in the regulation of the CSC and EMT phenotypes. We used a gemcitabine-resistant (GR) Patu8988 cell line, which exhibited clear CSC and EMT phenotypes and showed reliance on glycolysis. Inhibition of glycolysis using 2-deoxy-D-glucose (2-DG) significantly enhanced the cytotoxicity of gemcitabine and inhibited the CSC and EMT phenotypes in GR cells both in vitro and in vivo. Intriguingly, the use of the reactive oxygen species (ROS) scavenger N-acetylcysteine (NAC) restored the CSC and EMT phenotypes. H O produced changes similar to those of 2-DG, indicating that ROS were involved in the acquired cancer stemness and EMT phenotypes of GR cells. Moreover, doublecortin-like kinase 1 (DCLK1), a pancreatic CSC marker, was highly expressed and regulated the stemness and EMT phenotypes in GR cell. Both 2-DG and H O treatment suppressed DCLK1 expression, which was also rescued by NAC. Together, these findings revealed that glycolysis promotes the expression of DCLK1 and maintains the CSC and EMT phenotypes via maintenance of low ROS levels in chemoresistant GR cells. The glycolysis-ROS-DCLK1 pathway may be potential targets for reversing the malignant behaviour of pancreatic cancer.