MicroRNAs: the primary cause or a determinant of progression in leukemia?

Abstract

Leukemia is a complex disease with many different types and subtypes caused by a huge diversity of genetic and epigenetic aberrations. Until recently, alterations of protein-coding genes were thought to be the sole cause of tumorigenesis. With the recent discovery of multiple types of non-coding RNAs, it has become evident that mutations in these also contribute to the development of cancer. Among the non-coding RNAs, microRNAs play a crucial role in cancer owing to their involvement in fundamental processes such as apoptosis, differentiation and proliferation. MicroRNAs are small noncoding RNAs (approximately 19–25 nucleotides in length) that bind to and downregulate multiple mRNA targets; in mammals, the production of over a third of all proteins is regulated by microRNAs [3]. Several studies demonstrated that microRNAs are involved in leukemia progression but their role as the primary cause or a determinant of progression in leukemia has been unclear. Some have been identified as oncogenes or tumor suppressor genes, which suggests that they are playing a central role in tumorigenesis, while others appear to be associated with a specific stage in disease progression. Deciphering the exact role of microRNAs in oncogenesis is important in order to improve the diagnosis and treatment of leukemia patients.