Natural tumor suppressors
microRNAs are naturally occurring molecules that control important functions in normal human cells by inhibiting the expression of other genes. This regulation of gene expression ensures that over 20,000 human protein-encoding genes are produced in the proper cells and at the proper levels. Each individual microRNA can inhibit the expression of multiple genes and therefore can impact a variety of normal cellular processes. Altered expression of microRNAs can disrupt these processes, resulting in the development of human diseases, including cancer.
Studies comparing the microRNA profiles of diseased and normal tissues from patients with cancer, obesity, cardiovascular diseases, neurodegenerative diseases, viral infections and a variety of other conditions have revealed consistent changes in the expression of several microRNAs for each disease. As a result, genes regulated by these microRNAs are also abnormally expressed, which can contribute to the development of the disease. Therapy with microRNA mimics aims to correct abnormal microRNA expression by increasing the naturally occurring microRNAs that are underexpressed in cancer cells with microRNA mimics.