MicroRNAs 103 and 107： potential molecular links between diabetes and cancerand cancer

The prevalence of type 2 diabetes （T2DM）, which is characterized by insulin resistance, is increasingdramatically worldwide, and it has become a major public health issue. T2DM and cancer are common diseases that are frequently diagnosed in the same individual and the relationship of them appears to be complex. Epidemiologic data have shown T2DM is significantly associated with cancer, but potential biologic links between the two diseases are not fully understood. MicroRNAs （miRNAs） are endogenously expressed RNAs consisting of 20-24 nucleotides that influence the expression of hundreds of genes that involved in numerous biological processes, including organ development, lipid metabolism, differentiation, apoptosis, and brain morphogenesis. MiRNAs are now shown to be stably expressed in serum,~ plasma,2 or blood.3＇4 Moreover, the unique expression patterns of these circulating miRNAs are correlated with specific human diseases,5 including various types of cancer and diabetes. Therefore, miRNAs in serum or plasma are emerging as novel blood-based fingerprints for the detection of human cancers with diabetes, especially at an early stage. Accumulating studies have association between T2DM demonstrated a significant and tumorigenesis. One of the mechanisms underlying is insulin resistance, which contributes to the development of T2DM and cancer. High expression of miRNAs 103 and 107 （miR-103/107） leads to insulin resistance by down regulating caveolin-1, which is the direct target gene of miR-103/1076 and also a critical regulator of insulin receptor. Downregulation of caveolin-1 is susceptible to be tumorigenesis.7 Emerging evidence suggests the important role of miR-103/107 in the development and progression of breast and colorectal cancer patients,8＇9 which of them are associated with diabetes, yet their roles in linking diabetes and cancer are only now beginning to be recognized. In this review, we discuss the current understanding of the molecular roles of miR-103/107 linking diabetes and cancer.