Cancer has recently surpassed heart disease as the leading cause of death in Americans under the age of 80 years. This staggering statistic is highlighted in the case of lung cancer. Lung cancer is the leading cause of cancer deaths in the USA with approximately 170,000 newly diagnosed cases each year. The role of miRNAs in various facets of human tumorigenesis,(such as cell proliferation, ifferentiation, invasion, apoptosis, angiogenesis, migration, and motility) begs the question whether reverting these anomalies of the miRNome can be effectively harnessed for therapeutic gains? Promising preclinical data from many groups encourage this hypothesis and provide the biological enthusiasm for clinical studies in this direction. Re-introduction of miRNAs down-regulated in cancer and/or silencing of miRNAs up-regulated in the tumor may drive apoptosis in cancer cells and lead to a desirable therapeutic outcome.
miR-21 is said to be one of the well characterized mi RNAs and over expressed in various solid tumors including prostate cancers and lung cancers.micro-RNA-21 promoter had been reported to contain highly conserved regions with consensus binding sites for several transcriptional factors, including activator protein 1 (AP-1) and factors of the forkhead family (FOXO), such as FOXO3a.MicroRNA-155 is believed to be encoded in B-cell integration cluster (BIC), a conserved region of the non-coding gene Some generally believe that miR-155 is a master oncogene. This review will focus on these two very important micro RNAs with particular reference to their roles in cancer