MicroRNA Alterations and Associated Aberrant DNA Methylation Patterns across Multiple Sample Types in Oral Squamous Cell Carcinoma

Abstract

BackgroundMicroRNA (miRNA) expression is broadly altered in cancer, but few studies have investigated miRNA deregulation in oral squamous cell carcinoma (OSCC). Epigenetic mechanisms are involved in the regulation of >30 miRNA genes in a range of tissues, and we aimed to investigate this further in OSCC.MethodsTaqMan® qRT-PCR arrays and individual assays were used to profile miRNA expression in a panel of 25 tumors with matched adjacent tissues from patients with OSCC, and 8 control paired oral stroma and epithelium from healthy volunteers. Associated DNA methylation changes of candidate epigenetically deregulated miRNA genes were measured in the same samples using the MassArray® mass spectrometry platform. MiRNA expression and DNA methylation changes were also investigated in FACS sorted CD44high oral cancer stem cells from primary tumor samples (CSCs), and in oral rinse and saliva from 15 OSCC patients and 7 healthy volunteers.ResultsMiRNA expression patterns were consistent in healthy oral epithelium and stroma, but broadly altered in both tumor and adjacent tissue from OSCC patients. MiR-375 is repressed and miR-127 activated in OSCC, and we confirm previous reports of miR-137 hypermethylation in oral cancer. The miR-200 s/miR-205 were epigenetically activated in tumors vs normal tissues, but repressed in the absence of DNA hypermethylation specifically in CD44high oral CSCs. Aberrant miR-375 and miR-200a expression and miR-200c-141 methylation could be detected in and distinguish OSCC patient oral rinse and saliva from healthy volunteers, suggesting a potential clinical application for OSCC specific miRNA signatures in oral fluids.ConclusionsMiRNA expression and DNA methylation changes are a common event in OSCC, and we suggest miR-375, miR-127, miR-137, the miR-200 family and miR-205 as promising candidates for future investigations. Although overall activated in OSCC, miR-200/miR-205 suppression in oral CSCs indicate that cell specific silencing of these miRNAs may drive tumor expansion and progression.

The functional significance of microRNA-375 in human squamous cell carcinoma: aberrant expression and effects on cancer pathways

“…Several groups have reported that reduced expression of miR-375 could be a biomarker for HNSCC. 18,21,37 The expression levels of miR-375 were found to be lower in oral SCC patient oral rinse and saliva compared with those in healthy controls. 21 The expression ratio miR-221:miR-375 could be useful for distinguishing HNSCC from normal epithelium.…”

“…18,21,37 The expression levels of miR-375 were found to be lower in oral SCC patient oral rinse and saliva compared with those in healthy controls. 21 The expression ratio miR-221:miR-375 could be useful for distinguishing HNSCC from normal epithelium. 18 Another report showed that low miR-375 expression levels significantly correlated with cancer survival and distant metastasis.…”

“…In this review, we have listed nine miRNA expression signatures in HNSCC and ESCC. 12,13,15, [18][19][20][21][22][23] Differentially expressed miRNAs are summarized based on the nine signatures in Table 1. Recently, we conducted miRNA expression signature analyses in hypopharyngeal-SCC, maxillary sinus SCC and ESCC using clinical specimens.…”

“…16,17 Other research groups also showed downregulation of miR-375 in HNSCC and ESCC and other types of human cancers. [18][19][20][21][22][23][24][25][26][27][28][29][30][31] In this review, we focus on HNSCC and ESCC and describe the aberrant expression of miRNAs in these cancers and the cancer pathways they may regulate in these diseases.…”

Effect of HPV status, smoking and alcohol consumption, on miRNA expression in oral cancer - a review of the literature

“…MiR-375 was confirmed as a strongly repressed miRNA in OSCC. Wiklund et al reported a 10-fold decrease of expression in tumours compared to matched adjacent tissue, and a 1000-fold change when compared to healthy epithelium [70]. They also suggested that miRNA-375 was probably epithelial specific, highlighted by two orders of magnitude higher miR-375 expression in healthy epithelium than stroma.…”