MaTAR25LncRNA Regulates theTensin1Gene to Impact Breast Cancer Progression

SUMMARY Misregulation of long non-coding RNA genes has been linked to a wide variety of cancer types. Here we report on Ma mmary T umor A ssociated R NA 25 ( MaTAR25 ), a nuclear enriched and chromatin associated lncRNA that plays a role in mammary tumor cell proliferation, migration, and invasion, both in vitro and in vivo . MaTAR25 functions by interacting with purine rich element binding protein B (PURB), and associating with a major downstream target gene Tensin 1 ( Tns1 ) to regulate its expression in trans . Knockout of MaTAR25 results in down-regulation of Tns1 leading to a reorganization of the actin cytoskeleton, and a reduction of focal adhesions and microvilli. The human ortholog of MaTAR25 , LINC01271 , is upregulated with human breast cancer stage and metastasis. SIGNIFICANCE LncRNAs have great potential to reveal new regulatory mechanisms of function as well as having exciting therapeutic capacity given their ease of being targeted by nucleic acid drugs. Our study of MaTAR25, and its human ortholog LINC01271, reveal an unexpected function of this lncRNA in breast cancer progression by regulating Tns1 gene expression, whose protein product is a critical component of focal adhesions linking signaling between the extracellular matrix and the actin cytoskeleton. We identified LINC01271 as the human ortholog of MaTAR25 , and importantly, increased expression of LINC01271 is associated with poor patient prognosis and cancer metastasis. Our findings demonstrate that LINC01271 represents an exciting therapeutic target to alter breast cancer progression.