Cluster microRNAs miR-194 and miR-215 suppress the tumorigenicity of intestinal tumor organoids

Tumor stem cells with self-renewal and multipotent capacity play critical roles in the initiation and progression of cancer. Recently, a new 3-D culture system known as organoid culture has been developed, allowing Lgr5-positive stem cells to form organoids that resemble the properties of original tissues. Here we established organoids derived from intestinal tumors of Apc^min/+ mice and normal intestinal epithelia of C57BL/6J mice and investigated the roles of microRNA (miRNA) in intestinal tumor organoids. The results of microarray analyses revealed that expression of the cluster miRNAs, miR-194 and miR-215 was markedly suppressed in intestinal tumor organoids in comparison with organoids derived from normal intestinal epithelia. Enforced expression of miR-194 resulted in inhibition of E2f3, a positive regulator of the cell cycle and growth suppression of intestinal tumor organoids. In addition, enforced expression of miR-215 suppressed the cancer stem cell signature through downregulation of intestinal stem cell markers including Lgr5. These findings indicate that the miRNA cluster including miR-194 and miR-215 plays important roles in suppressing the growth and attenuating the stemness of intestinal tumor organoids.