DIFFERENTIAL EXPRESSION OF MICRORNAs IN LUNG CANCER: A REVIEW ARTICLE

MicroRNAs (miRNAs) are small non-coding RNA molecules of approximately 16-24 nucleotide length. The miRNA biogenesis is a 2 step cleavage process mediated by Dorsha and Dicer. The nuclear cleavage by Dorsha / DiGeorge syndrome critical region 8 (DGCR8) generates 60-70 nucleotide long precursor microRNA (pre-miRNA). Furthermore, the pre-miRNA is exported to the cytoplasm by exportin 5 to be cleaved by Dicer. This resultant miRNA is further processed to generate a mature miRNA and get assembled into a RNA-induced silencing complex (RISC). Hence leading to transcriptional repression of the target mRNAs. It has been reported that one miRNA may target many genes accounting from a few to as many as thousands. Lung cancer (LC) ranks third worldwide and is marked by poor prognosis. The early staged LC patients usually exhibit no symptoms and the condition worsens till the time of first diagnosis. Therefore, studies are required to outline good early detecting and surveillance biomarkers for LC. Several evidences support the role of miRNAs in the pathogenesis of LC. They show differential expression pattern i.e. may be either upregulated or downregulated. The oncogenic miRNAs remain upregulated while the tummor suppressive miRNAs remain downregulated. In LC miRNAs are the important factors for tumour initiation, differentiation, apoptosis, proliferation as well as tumor progression. Thus, this review article focuses on the diagnostic significance of miRNAs in LC