MicroRNA Profile of Human Small Intestinal Tumors Compared to Colorectal Tumors

Abstract

Small intestinal tumors (adenoma and adenocarcinoma, SIT) are rare, and their microRNA (miRNA) expression profiles have not been established. Previously, we reported a relationship between miRNA expression profiles and the development, growth, morphology, and anticancer drug resistance of colorectal tumors. Here, we demonstrate that the miRNA expression profile of SIT is significantly different from those of tumors of the colon. We compared the onco-related miRNA expression profiles of SIT and colorectal tumors and found them to be different from each other. The expressions of miR-143 and miR-145 were frequently downregulated in SIT and colorectal tumors but not in sessile serrated adenoma/polyp tumors. The profiles of SIT and colorectal carcinomas of miR-7, miR-21, and miR-34a were considerably different. Upregulation of miR-31 expression was not found in any SIT cases. Our data suggested that miR-143 and miR-145 might act as anti-oncomirs common to adenocarcinoma of the small intestine, similar to those of colorectal adenoma and other cancers. However, the expression profiles of the other miRNAs of SIT were significantly different from those of colorectal tumors. These findings contribute useful insights into the tumor development and diagnosis of SIT.

Keywords: carcinogenesis; colorectal adenoma and adenocarcinoma; miR-143; miR-145; miR-31; onco-related microRNA; small intestinal adenoma and adenocarcinoma.

Figure 1

Box-and-whisker plots of miR-143, miR-145, miR-7, miR-21, miR-34a, and miR-31 expression in small intestinal tumors and colorectal tumors. The relative expression level in normal tissue was defined as 1. SIT, small intestinal tumor (adenoma and adenocarcinoma); FAP, familial adenomatous polyposis; SSA/P, sessile serrated adenoma/polyp; ×, upper outlier (over the 3rd quartile + 1.5 × interquartile range).

Figure 2

Expression profiles of miR-7, miR-34a, and miR-21 with or without downregulation of miR-143 and miR-145 in human colorectal tumors. ↓, downregulated; ↑, upregulated; SIT, small intestinal tumor (adenoma and adenocarcinoma); FAP, familial adenomatous polyposis; SSA/P, sessile serrated adenoma/polyp.