Reduced accumulation of specific microRNAs in colorectal neoplasia.

Short non-coding RNAs are known to regulate cellular processes including development, heterochromatin formation, and genomic stability in eukaryotes. Given the impact of these processes on cellular identity, a study was undertaken to investigate possible changes in microRNA (miRNA) levels during tumorigenesis. A total of 28 different miRNA sequences was identified in a colonic adenocarcinoma and normal mucosa, including 3 novel sequences and a further 7 that had previously been cloned only from mice. Human homologues of murine miRNA sequences, miR-143 and miR-145, consistently display reduced steady-state levels of the mature miRNA at the adenomatous and cancer stages of colorectal neoplasia.