Role of miRNA in distinguishing primary brain tumors from secondary tumors metastatic to the brain.

Cancer is the result of complex processes that involve multiple molecular alterations. The understanding of such complexity has been improved by the advent of a new class of small, noncoding RNA gene products known as microRNAs (or miRNAs). miRNAs play an essential role in cancer development and progression by modulating gene expression binding to target mRNA, causing either mRNA degradation or translation inhibition.

Arylamine N-acetyltransferase-1 is highly expressed in breast cancers and conveys enhanced growth and resistance to etoposide in vitro.

Comparative two-dimensional proteome analysis was used to identify proteins differentially expressed in multiple clinical normal and breast cancer tissues. One protein, the expression of which was elevated in invasive ductal and lobular breast carcinomas when compared with normal breast tissue, was arylamine N-acetyltransferase-1 (NAT-1), a Phase II drug-metabolizing enzyme. NAT-1 overexpression in clinical breast cancers was confirmed at the mRNA level and immunohistochemical analysis of NAT-1 in 108 breast cancer donors demonstrated a strong association of NAT-1 staining with estrogen receptor-positive tumors.