MicroRNAs in cancer treatment and prognosis

Abstract

Disturbances in microRNA expression by epigenetic alterations and mutations may promote not only tumorigenesis but also tumor aggressiveness, invasion, metastasis, and resistance to chemotherapy and radiotherapy. Several studies have profiled microRNA expression in normal and tumorigenic tissues, demonstrating a unique microRNA signature, which can be used as a marker for cancer diagnosis and prognosis. This review discusses the importance of microRNAs as regulatory biomolecules involved in cancer, focusing on microRNAs related to cancer invasion, metastasis, epigenetic alterations, chemoresistance, and radioresistance. The identification of both differentially expressed microRNAs in tumors and their target genes provides new tools for gene therapy; the re-expression of microRNAs silenced by cancer development or the silencing of oncogenic microRNAs can be effective in the blockade of cancer-related cell proliferation.

Keywords: MicroRNA; chemotherapy; epigenetic modifications; metastasis; radiotherapy.

Figure 1

MicroRNA biogenesis, with a special focus on the roles of DROSHA and DICER and the formation of the RISC complex.

Figure 2

Overview of the interplay between miRNAs and DNA methylation in tumor cells. Dashed lines denote the original function in normal cells that is lost in tumor cells. Open circles: unmethylated CpG sites; filled circles: methylated CpG sites.

Figure 3

Overview of miRNAs involved in metastasis progression. Dashed lines denote the original function in normal cells that is lost or altered in tumor cells.