Abstract
MicroRNAs (miRNAs) are small [~21 nucleotide (nt)] non coding RNAs (ncRNAs) that regulate gene expression posttranscriptionally. About 3.0% of human genes encode for miRNAs, and up to 30.0% of human protein coding genes may be regulated by miRNAs. Currently, more than 2000 unique human mature microRNAs are known. MicroRNAs play a key role in diverse biological processes including development, cell proliferation, differentiation and apoptosis. These processes are commonly dysregulated in cancer, implicating miRNAs in carcinogenesis, where they act as tumor supressors or oncogenes. Several miRNAs are associated with breast cancer. Here we present our initial results of miRNA analyses of breast cancer tissues using quantitative real time-polymerase chain reaction (ReTi-PCR) (qPCR) involving stem-loop reverse transcriptase (RT) primers combined with TaqMan® PCR and miRNA microarray analysis