Diverse microRNAs with convergent functions regulate tumorigenesis

Abstract

MicroRNAs (miRNAs) regulate several biological processes, including tumorigenesis. In order to comprehend the roles of miRNAs in cancer, various screens were performed to investigate the changes in the expression levels of miRNAs that occur in different types of cancer. The present review focuses on the results of five recent screens, whereby a number of overlapping miRNAs were identified to be downregulated or differentially regulated, whereas no miRNAs were observed to be frequently upregulated. Furthermore, the majority of the miRNAs that were common to >1 screen were involved in signaling networks, including wingless-related integration site, receptor tyrosine kinase and transforming growth factor-β, or in cell cycle checkpoint control. The present review will discuss the aforementioned miRNAs implicated in cell cycle checkpoint control and signaling networks.

Keywords: cancer stem cell; microRNA; microarray; signal transduction; tumorigenesis.

Figure 1.

Wnt signaling interacts with intercellular junction components. β-catenin is involved in Wnt signaling and focal adhesions. β-catenin is a key downstream target of the Wnt signaling pathway and is also an important part of intercellular junctions. The loss of cell-cell contact in the epithelium leads to the formation of cancer cells, which is the initial stage of the metastatic process. Miscellaneous miRs from previous screens discussed in the present review were identified to be involved in this complicated network. Wnt, wingless-related integration site; miR, microRNA; β-cat, β-catenin; α-cat, α-catenin; Frz, frizzy.