MicroRNA involvement in mammary gland development and breast cancer

Abstract

-MicroRNA (miRNA) are small non-coding RNA that post-transcriptionally regulate gene expression. In humans, miRNA genes may account for 2 to 3% of the total number of genes. Although the biological functions of most miRNA are unknown, their importance for development, cell proliferation, cell death, and morphogenesis has been demonstrated in several species. One could thus speculate that miRNA should be involved in the regulation of one of the organs that can undergo cycles of cell division, differentiation and dedifferentiation in the adult, the mammary gland. In this paper we summarise several reports dealing with the potential implication of miRNA in the mammary gland, most of them focussed on pathological situations, such as the appearance of breast cancer. These data suggest an implication of miRNA on mammary gland biology. However, direct evidence of this is still lacking. Expression profile analysis of miRNA during the normal mammary gland development could help in addressing this question and in identifying miRNA potentially involved. To this aim, we undertook such an analysis on mouse mammary gland at different stages (virgin, pregnancy, lactation and involution) and will present our preliminary results. gene regulation / mouse / RNA interference / mammary tissue

Transcriptomic analysis reveals key regulators of mammogenesis and the pregnancy-lactation cycle

“…Focusing on miRNAs, we detected 231, 160, and 226 miRNAs during pregnancy, lactation, and involution, respectively. Our results agree with a previous report, where nine miRNAs were verified [30]. Among the miRNAs that were identified, 21 were up- regulated and 72 were down-regulated from pregnancy to lactation, while 69 that were up-regulated and 12 that were down-regulated from lactation to involution were defined as DEGs.…”

“…We first mapped the 50-bp full-length reads to the reference sequence with up to five mismatches, and the un-mapped reads were then mapped to our junction library. Thereafter, we repeated the above two steps for the first 45,40,35,30, and 25-bp truncated reads with up to 4, 4, 3, 3, and 2-bp mismatches, respectively. Ribosomal RNA-related reads were filtered out at the beginning of the read mapping.…”

Milk Protein Synthesis in the Lactating Mammary Gland: Insights from Transcriptomics Analyses

“…Several studies have been published about the use of microarray technologies to investigate transcriptomics adaptation of mammary gland during development, lactation, and involution (some references among others [34,[172][173][174][175][176]). Also the use of microarrays to study the miRNA in mammary gland development has seeing an increase in popularity [177][178][179].…”

MicroRNAs and Breast Cancer

“…In addition, RNA samples analyzed were from 18 adult and 2 fetal normal human tissues and therefore were not adequate to assess miRNA expression patterns during the complex and distinct stages of normal mammary development. More recently, a preliminary study was performed to analyze the expression pattern of 22 miRNAs in mouse mammary gland from various development stages [80]. Taken together with the fact that of these 22 miRNAs, over half (13/22) were not detected in the mammary gland, this is not a comprehensive enough study to assess the role of miRNAs in normal mammary gland development.…”