Abstract 6885: Investigating a novel role of DCLK1 isoforms in colitis and colitis associated colon cancer

Abstract

Abstract Chronic intestinal inflammation in patients diagnosed with inflammatory bowel disease (IBD) significantly increases their risk of colorectal cancer (CRC). Despite the rising global frequency of IBD, the precise mechanisms that regulate the transition from IBD to colon cancer are poorly understood. Doublecortin-like kinase 1 (DCLK1) is a protein with two major isoforms, DCLK1-L and DCLK1-S. Previous studies have shown that hypermethylation of the DCLK-1α promoter encoding DCLK1-L, particularly in colorectal cancer, allows switching to the DCLK1-S isoform that confers an invasive tumor phenotype. The DCLK1-L is a tuft cell marker that protects against colitis by sensing and eliminating gut pathogenic infection through various mechanisms. On the contrary, the role of DCLK1-S in colitis and colitis-associated cancer has not been thoroughly investigated. Studies from our lab have identified a marked elevation of DCLK1-S in tissue samples of IBD patients. We also recently discovered that DCLK1-S is predominantly expressed in Ly6G+; MHCII- neutrophils, which coincide with elevated levels of inflammation and tissue damage in the colon. To further understand the role of DCLK1 isoforms in driving the progression of colitis to colon cancer, we bred Dclk1fl/fl mice with MRP8-Cre-ires/GFP mice to generate Dclk1fl/fl;MRP8-Cre+/- that eliminates DCLK1-L upon tamoxifen injection resulting in sustained expression of DCLK1-S in the granulocytes especially neutrophils. When infected with Citrobacter rodentium (CR), MRP8;Dclk1−/− mice compared to MRP8;Dclk1+/− or WT mice developed more severe colitis. We have also discovered a novel interaction between DCLK1-S and MMP13 in an unbiased docking study that correlated with significant co-localization of DCLK1-S with MMP13 in the colons of CR-infected mice. Employing a knock-in mice over-expressing the DCLK1-S +19 under the CAG promoter, the DCLK1-MMP13 co-localization correlated with severe ulceration and colitis with loss of crypts and immune cell infiltration including Ly6G+ neutrophils. Studies are underway to see if the severity of colitis in MRP8;Dclk1−/− mice translates into enhanced tumorigenesis and to see if potential interaction between DCLK1-S and MMP13 could provide a plausible mechanism of colitis progression to colon cancer through ECM remodeling and tissue damage. Citation Format: Kafayat Aderonke Yusuf, Badal C. Roy, Shrikant Anant, Shahid Umar. Investigating a novel role of DCLK1 isoforms in colitis and colitis associated colon cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 6885.