NEAT1 enhances drug sensitivity by inhibiting cancer stem-like cells in triple-negative breast cancer

Abstract

Background: Accumulating evidence showed that long non-coding RNAs (lncRNAs) dysregulation is the hallmark of cancer. Nuclear paraspeckle assembly transcript 1 (NEAT1) has been reported to overexpress in many cancers, and promote cell growth and disease progression. However, the role of NEAT1 on drug sensitivity and stem-cell like property in triple-negative breast cancer is largely unknown. Methods: LncRNA expression profile were compared between breast cancer patients and healthy individuals using lncRNA array. Large scale validation of NEAT1 expression in blood samples were performed by real-time PCR. Triple-negative breast cancer (TNBC) cells, MDA-MB-231 and its cisplatin resistance subline (MDA-MB-231/cis) were used. Stable transfection of cells with NEAT1 knockdown by shRNA, and evaluated single cell clonogenic assay, aldehyde dehydrogenase (ALDH) activity, CD44+/CD24- and other cancer stem cell (CSC) markers. Drug sensitivity assay, flow cytometry analysis, immunofluorescence staining and xenograft model were used to assess the functional role of NEAT1. Results: Array data showed that NEAT1 was the top upregulated lncRNAs in the plasma of breast cancer patients. Consistent with the array data, validation of larger cohort of patients and healthy individuals (n=369) also demonstrated a higher expression of NEAT1 in breast cancer patients, in particular TNBC subtype. Knockdown of NEAT1 by shRNA sensitized breast cancer cells to cisplatin and taxol treatment. Cell proliferation and colony formation abilities were reduced with S-phase cell cycle arrest in shNEAT1 cells. Flow cytometry analysis revealed an induction of apoptosis with increased cleaved caspase-3. Cells expressing shNEAT1 abrogated ALDH activity, CD44+/CD24- subpopulation and expression of CSC markers (SOX2, NANOG and OCT4). More importantly, shNEAT1 cells retarded tumor growth in xenograft mice model and reduced CSC markers. Conclusion: Taken together, NEAT1 expression is differentially expressed in breast cancer patients, and particularly higher in patients with TNBC. These findings suggest a potent therapeutic target to improve drug sensitivity in patients with TNBC.