Long noncoding RNA MYOSLID promotes invasion and metastasis by modulating the partial epithelial-mesenchymal transition program in head and neck squamous cell carcinoma

BACKGROUND: Partial epithelial mesenchymal transition (p-EMT) was found to play a potential role in the initial stage of metastasis in human head and neck squamous cell carcinoma (HNSCC). Some long noncoding RNAs (lncRNAs) have been reported to function as promoters or inhibitors of cancer metastasis. This study aimed to identify p-EMT-related lncRNAs in HNSCC. METHODS: Differentially expressed lncRNAs (DE-lncRNAs) and mRNAs (DEGs) in HNSCC obtained from The Cancer Genome Atlas (TCGA) were screened out by using the “edgeR” package. DE-lncRNAs in the Oral squamous cell carcinoma (OSCC) lncRNA microarray dataset GSE84805 were screened out by using the “limma” package. Slug-related lncRNAs were determined by Pearson correlation analysis (|Pearson correlation coefficient| ≥ 0.4, p < 0.01) based on TCGA. Survival analysis were performed for the overlapping DE-lncRNAs by using the “Survival” package. Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analyses were used to predict the potential functions of MYOSLID. RT-qPCR and In Site Hybridization (ISH) were used to explore the MYOSLID expression and its clinical significance in HNSCC specimens. Immunohistochemical staining, siRNA, wound healing assay, transwell assay, and western blot were used to explore the biological function and potential molecular mechanisms. RESULTS: MYOSLID was identified as a Slug-related lncRNA and with prognostic value among the 9 overlapping DE-lncRNAs. GO and KEGG analyses revealed that MYOSLID was closely related to important biological processes and pathways that regulate cancer metastasis. The results of univariate and multivariate Cox regression analysis based on TCGA and HNSCC tissue microarray data suggested MYOSLID was an independent prognostic factor. MYOSLID expression in HNSCC was closely correlated with Slug, PDPN and LAMB3. The knockdown of MYOSLID in OSCC cell line significantly inhibited cell migration and invasion compared to those in the control cells. In addition, the knockdown of MYOSLID significantly reduced Slug, PDPN and LAMB3 expression levels. However, the knockdown of MYOSLID had no effect on the expression levels of the EMT biomarkers E-cadherin and Vimentin. CONCLUSIONS: Our study revealed that MYOSLID expression was closely related to the p-EMT program in HNSCC, and it might be a new predictive biomarker for aggressive HNSCC. ELECTRONIC SUPPLEMENTARY MATERIAL: The online version of this article (10.1186/s13046-019-1254-4) contains supplementary material, which is available to authorized users.