Upregulation of long noncoding RNA LOC100507661 promotes tumor aggressiveness in thyroid cancer

Recent advances in next-generation sequencing have revealed a variety of long noncoding RNAs (lncRNAs). However, studies of lncRNAs are at a very early stage, our knowledge of the biological functions and clinical implications remains limited. To investigate the roles of lncRNAs in thyroid cancers, we verified 56 lncRNAs identified as potential cancer-promoting genes in a previous study that analyzed 2394 tumor SNP arrays from 12 types of cancer. Based on verified sequence information in NCBI and Ensembl, we ultimately selected three candidate lncRNAs for detailed analysis. One of the candidates, LOC100507661, was strongly upregulated in thyroid cancer tissues relative to paired contralateral normal tissue. LOC100507661 was easily detectable in papillary and anaplastic thyroid cancer cell lines such as TPC1, BCPAP, C643, and 8505C, but not in the follicular thyroid cancer cell line FTC133. Stable overexpression of LOC100507661 promoted cell proliferation, migration, and invasion of thyroid cancer cells. Lymph node metastasis and BRAF V600E mutations were more frequent in papillary thyroid cancers with high LOC100507661 expression. Our data demonstrate that LOC100507661 expression is elevated in human thyroid cancer and may play a critical role in thyroid carcinogenesis.