SOX9 Is Highly Expressed in Nonampullary Duodenal Adenoma and Adenocarcinoma in Humans

Background/Aims: SOX9 is a marker for stem cells in the intestine, and overexpression of SOX9 is found in gastric and colon cancer; however, the expression of SOX9 in non-ampullary duodenal adenoma and adenocarcinoma has not yet been evaluated. This study aimed to investigate SOX9 expression in nonampullary duodenal adenoma and adenocarcinoma by immunohistochemistry. Methods: We evaluated SOX9 expression in 43 clinical samples (nonampullary duodenal adenoma in 22 lesions and nonampullary duodenal adenocarcinoma in 21 lesions) resected under endoscopic mucosal resection or endoscopic submucosal dissection. Results: SOX9 was expressed in part of the base of the normal duodenal mucosa surrounding adenomas and adenocarcinomas. In contrast, SOX9-positive cells were found in more than half of the crypts from the bottom part of the crypt in all of the 43 samples. Moreover, in 15 adenoma samples (68.2%) and 19 carcinoma samples (90.5%), SOX9 was expressed in more than three-quarters of the crypts from the bottom part of the crypt. Conclusions: SOX9 is overexpressed in nonampullary duodenal adenoma and adenocarcinoma in humans.