MicroRNA Gene Expression Deregulation in Human Breast Cancer

TLDR

MicroRNAs are small noncoding RNAs that regulate gene expression, and their aberrant expression has been linked to various diseases, including cancers, with prior studies showing distinct miRNA signatures in leukemias. The study aims to demonstrate that miRNAs are aberrantly expressed in human breast cancer compared to normal breast tissue. The authors confirmed miRNA expression differences using microarray and Northern blot analyses. The miRNA expression profile distinguished normal from cancerous breast tissue, with mir‑125b, mir‑145, mir‑21, and mir‑155 most deregulated, and certain miRNAs correlated with hormone receptor status, tumor stage, vascular invasion, and proliferation.

Abstract

Abstract MicroRNAs (miRNAs) are a class of small noncoding RNAs that control gene expression by targeting mRNAs and triggering either translation repression or RNA degradation. Their aberrant expression may be involved in human diseases, including cancer. Indeed, miRNA aberrant expression has been previously found in human chronic lymphocytic leukemias, where miRNA signatures were associated with specific clinicobiological features. Here, we show that, compared with normal breast tissue, miRNAs are also aberrantly expressed in human breast cancer. The overall miRNA expression could clearly separate normal versus cancer tissues, with the most significantly deregulated miRNAs being mir-125b, mir-145, mir-21, and mir-155. Results were confirmed by microarray and Northern blot analyses. We could identify miRNAs whose expression was correlated with specific breast cancer biopathologic features, such as estrogen and progesterone receptor expression, tumor stage, vascular invasion, or proliferation index.