Abstract 1731: Overexpression of DCLK1 in pancreatic cancer activates KRAS/PI3K/MTOR pathway signaling and supports tumorigenesis, invasiveness, and stemness
Authors: Qu Dongfeng , Weygant Nathaniel , May Randal , Berry William , Tomasek James , Chandrakesan Parthasarathy , Schlosser Michael , Houchen Courtney 
Published: July 2016

Abstract
Pancreatic ductal adenocarcinoma (PDAC) has the worst prognosis of any major malignancy with less than a 6% 5-year survival rate. Oncogenic KRAS mutation plays a key role in PDAC tumorigenesis with nearly 95% of PDAC harboring mutationally activated KRAS. Cells with cancer stem cell-like (CSC) properties have been identified in PDAC. These cells are often resistant to conventional chemotherapy and radiation therapy, and as such may explain why current treatments do not cure PDAC or prevent recurrences. It is suggested that “driver” mutations in these stem-like cells may be the root cause of PDAC. Doublecortin-like kinase 1 (DCLK1), is overexpressed and marks a population of tumor-initiating cells in PDAC. It regulates key oncogenes, pluripotency factors, angiogenic factors, and epithelial mesenchymal transition (EMT) related transcription factors. In this study we evaluated the role of DCLK1 in KRAS-mediated signaling in PDAC. Human pancreatic cancer cells (AsPC-1 and MiaPaCa-2) were infected with Lentivirus containing human DCLK1 cDNA sequence to overexpress DCLK1 or red fluorescent protein (RFP) cDNA sequence as control. The expressing levels of DCLK1, active KRAS, and proteins in KRAS/PI3K/mTOR pathway were analyzed by western blotting. The proliferative and invasive potential of these cells were compared using a MTT assay for proliferation, wound healing assay for migration, soft agar assay for clonogenicity, and Matrigel coated transwell assay for invasion. Gemcitabine, Rapamycin, and PI3K inhibitors were used for evaluation. Analysis of human PDAC was performed using the TCGA PAAD dataset. Here we report that DCLK1 protein levels were increased more than 20 fold in AsPC-DCLK1 and MP2-DCLK1 cells resulting in activation of KRAS which was reversible by DCLK1-inhibitor XMD8-92. Compared to RFP control cells, AsPC-DCLK1 and MP2-DCLK1 cells exhibited a more than 20% increase in proliferation, approximately 30% increase in colony formation, 20% increase in migration, and a 2-fold increase (p &lt; 0.05) in invasion. Evidence from TCGA PAAD demonstrated that pancreatic tumors expressing high levels of DCLK1 had activated PI3K/AKT/MTOR-pathway signaling suggesting greater KRAS activity. These data taken together suggest that DCLK1 promotes KRAS-driven PI3K/AKT/mTOR signaling in PDAC leading to increased migratory, invasive, anti-apoptotic effects, stem-like and tumorigenic properties.
Citation Format: Dongfeng Qu, Nathaniel Weygant, Randal May, William Berry, James Tomasek, Parthasarathy Chandrakesan, Michael Schlosser, Courtney Houchen. Overexpression of DCLK1 in pancreatic cancer activates KRAS/PI3K/MTOR pathway signaling and supports tumorigenesis, invasiveness, and stemness. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 1731.