Cyclooxygenase 2 in Gastric Carcinoma Is Expressed in Doublecortin- and CaM Kinase-Like-1-Positive Tuft Cells

Background/Aims: Doublecortin and CaM kinase-like-1(DCAMKL1) is a marker of stem cells expressed predominantlyin the crypt base in the intestine. However, DCAMKL1-positive cells have been shown to be differentiated tuft cellsrather than quiescent progenitors. Tuft cells are the onlyepithelial cells that express cyclooxygenase 2 (COX-2) in thenormal intestinal epithelium. We previously generated Cdx2-transgenic mice as model mice for intestinal metaplasia andgastric carcinoma. In the current study, we investigated theassociation between COX-2 and DCAMKL1 in gastric carcinoma. Methods: We examined the association between COX-2 and DCAMKL1 expression in gastric carcinomas in clinicalsamples (early gastric well-differentiated adenocarcinoma)and Cdx2-transgenic mice, and the DCAMKL1-transgenicmouse stomach using immunohistochemistry and quantitativereal-time polymerase chain reaction. Results: The COX-2-expressing cells were scattered, not diffusely expressed, ingastric carcinomas from humans and Cdx2-transgenic mice. DCAMKL1-positive cells were also scattered in the gastriccarcinomas, indicating that tuft cells could still be presentin gastric carcinoma. COX-2 was expressed in DCAMKL1-positive tuft cells in Cdx2- and DCAMKL1-transgenic mousestomachs, whereas the Sox9 transcription factor was ubiquitouslyexpressed in gastric carcinomas, including COX-2-positive cells. Conclusions: COX-2 is expressed in DCAMKL1-expressing quiescent tuft cells in gastric carcinoma. (Gut Liver 2014,8:508-518)