microRNA-1/133a and microRNA-206/133b clusters: Dysregulation and functional roles in human cancers

Nijiro Nohata 1,2 , Toyoyuki Hanazawa 2 , Hideki Enokida 3 , Naohiko Seki 1 1 Department of Functional Genomics, Chiba University Graduate School of Medicine, Chiba, Japan 2 Department of Otorhinolaryngology/Head and Neck Surgery, Chiba University Graduate School of Medicine, Chiba, Japan 3 Department of Urology, Graduate School of Medical and Dental Sciences, Kagoshima University, Kagoshima, Japan Received: January 25, 2012; Accepted: January 25, 2012; Published: February 4, 2012; Keywords: cancer, miRNA, miR-1, miR-133a, miR-133b, miR-206 Correspondence: Naohiko Seki, email: // // Abstract MicroRNAs (miRNAs) are endogenous short non-coding RNA molecules that regulate gene expression by repressing translation or cleaving RNA transcripts in a sequence-specific manner. A growing body of evidence suggests that miRNAs are aberrantly expressed in many human cancers and that they play significant roles in the initiation, development and metastasis of human cancers. Genome-wide miRNA expression signatures provide information on the aberrant expression of miRNAs in cancers rapidly and precisely. Recently, studies from our group and others revealed that microRNA-1 (miR-1), microRNA-133a (miR-133a), microRNA-133b (miR-133b) and microRNA-206 (miR-206) are frequently downregulated in various types of cancers. Interestingly, miR-1-1/miR-133a-2, miR-1-2/miR-133a-1, and miR-206/miR-133b form clusters in three different chromosomal regions of the human genome – 20q13.33, 18q11.2 and 6p12.1, respectively. Here we review highlights of recent findings on the aberrant expression and functional significance of the miR-1/miR-133a and miR-206/miR-133b clusters in human cancers.