Mitotically associated long non-coding RNA is a tumor promoter in anaplastic thyroid cancer

BACKGROUND: Patients with anaplastic thyroid cancer (ATC), which is among the deadliest of all cancers, often have a poor response to traditional therapies. Currently, the role of long non-coding RNAs (lncRNAs) in ATC carcinogenesis is unclear. In this study, we analyzed the lncRNA expression profile of ATC with the aim of identifying potential molecular targets for treatment of the disease. METHODS: Whole transcriptome sequencing of three ATC and two normal thyroid (NT) samples was performed, and the lncRNA expression profile of ATC was analyzed. Original data as well as datasets deposited in the Gene Expression Omnibus (GEO) and The Cancer Genome Atlas (TCGA) were used for clinical validation. Cell proliferation, Transwell, and apoptosis assays were performed using ATC cell lines. Gene Ontology (GO) and gene set enrichment analyses (GSEA) were performed to determine the dysregulated pathways. RESULTS: Whole transcriptome sequencing revealed 182 lncRNAs to be differentially expressed in ATC. One of the lncRNAs, mitotically associated long non-coding RNA (MANCR; LINC00704), was significantly overexpressed in ATC cell lines and patient samples compared with NT and papillary thyroid cancer (PTC). MANCR depletion in ATC cells significantly inhibited cancer cell proliferation and invasion, and induced apoptosis. By further analyzing the transcriptome data, we identified 451 genes co-expressed with MANCR. GO and GSEA showed that the top dysregulated pathways were related to mitosis and cell cycle. CONCLUSIONS: MANCR is a tumor promoter in ATC, and its role in carcinogenesis is possibly associated with cell cycle regulation. Because MANCR expression is minimal in most normal tissues, it may serve as a potential target in the future treatment of ATC.