Alterations in
miRNA genes play a critical role in the pathophysiology of many, perhaps all, human
cancers:
cancer initiation and progression can involve alterations of
microRNA genes (
miRNAs) encoding small noncoding RNAs that can regulate gene expression. The main mechanism of microRNoma (defined as the full
complement of
microRNAs present in a genome) alteration in
cancer cell seems to result in aberrant gene expression characterized by abnormal levels of expression for mature and/or precursor
miRNA sequences in comparison with the corresponding normal tissues. Loss or amplification of
miRNA genes has been reported in a variety of
cancers, and altered patterns of
miRNA expression may affect cell cycle and survival programs. The causes of the widespread differential expression of
miRNA genes between malignant and normal cells can be explained by the genomic location of these genes in
cancer-associated genomic regions, by epigenetic mechanisms as well as by alterations of members of the processing machinery. Germline and somatic mutations in
miRNAs or polymorphisms in the mRNAs targeted by
miRNAs may also contribute to
cancer predisposition and progression.
miRNAs expression profiling has been exploited to identify
miRNAs potentially involved in the pathogenesis of human
cancers and has allowed the identification of signatures associated with diagnosis, staging, progression, prognosis, and response to treatment of human
tumors. Here we present a flowchart of principal steps to produce, analyze, and understand the biological significance of
miRNA microarray data.