DCLK1 expression in gastrointestinal stem cells and neoplasia

Doublecortin-like kinase (Dclk1), a gene involved in neurogenesis, has recently been found expressed in single cells of the human and murine adult gastrointestinal tract. Currently, there are opposing opinions on the exact identity and functional characteristics of DCLK1 positive cells. Some view them as gastrointestinal stem cells that fuel the self-renewal process, whereas others view them as an intestinal brush cells or as an enteroendocrine subtype. Interestingly, Dclk1 is over-expressed in several gastrointestinal malignancies, but is expressed at only low levels in normal gastrointestinal cells, making it a possible target for cancer therapy. In view of the recent therapeutic efforts to antagonize and target the cancer stem cell population, there has been ongoing interest in DCLK1. In this review we critically appraise the studies describing the expression of Dclk1 in the normal and neoplastic gastrointestinal tract as well as discuss the possible function and of Dclk1 in the gastrointestinal system and the potential clinical relevance as a tumor marker and a therapeutic target.