Abstract MS1-2: Long Noncoding RNAs in Breast Cancer Progression

Abstract

Abstract Long intergenic noncoding RNAs (lincRNAs) are pervasively transcribed in the genome, yet their potential involvement in human disease is not well understood. Recent studies of dosage compensation, imprinting, and homeotic gene expression suggest that individual lincRNAs can function as the interface between DNA and specific chromatin remodeling activities. We found that many lincRNAs become systematically dysregulated during breast cancer progression. A lincRNA termed HOTAIR is increased in expression in primary breast tumors and metastases, and HOTAIR expression level in primary tumors is a powerful predictor of eventual metastasis and death. Enforced expression of HOTAIR in epithelial cancer cells induced genome-wide re-targeting of Polycomb Repressive Complex 2 (PRC2) to an occupancy pattern more resembling embryonic fibroblasts, leading to altered histone H3 lysine 27 methylation, gene expression, and increased cancer invasiveness and metastasis in a manner dependent on PRC2. Conversely, loss of HOTAIR can inhibit cancer invasiveness, particularly in cells that possess excessive PRC2 activity. A second long noncoding RNA, named PANDA, is part of the DNA damage response mediated by p53 and controls the balance between cell death and cell cycle arrest. Collectively, these findings suggest that lincRNAs play active roles in modulating the cancer epigenome and may be important targets for cancer diagnosis and therapy. Citation Information: Cancer Res 2010;70(24 Suppl):Abstract nr MS1-2.