Altered expression pattern of circular RNAs in metastatic oral mucosal melanoma.

Circular RNAs (circRNAs) are known to be associated with carcinogenesis, and can serve as potential biomarkers for cancer diagnosis and therapeutic implications. However, little is known about their expression patterns in oral mucosal melanoma (OMM), an extremely rare cancer that is distinct from cutaneous melanoma for its clinical course and prognosis. To investigate circRNAs expression profile in OMM, we performed a circRNAs microarray to analyze 6 primary OMM samples with lymph nodes dissemination, and constructed a genome-wide circRNA profile. Our results revealed that 90 circRNAs were significantly dysregulated in the metastatic OMM tissues when compared to the paired adjacent tissues. Among them, hsa_circ_0005320, hsa_circ_0067531, hsa_circ_0008042 were significantly upregulated in primary tumor and metastatic lymph nodes compared to paired adjacent normal tissues and non-metastatic lymph nodes, whereas the expression of hsa_circ_0000869 and hsa_circ_0000853 were downregulated relatively. Gene Ontology (GO) and pathway analyses of differentially expressed circRNAs indicated that these identified circRNAs might play important roles in protein modification, protein binding and cellular metabolism in metastatic OMM. Functions of several selected circRNA were also identified. In addition, by using bioinformatics predictions, we further demonstrated that hsa_circ_0005320, hsa_circ_0067531 and hsa_circ_0000869 could serve as competing endogenous RNA (ceRNA), which might regulate tumorigenesis and metastatic of OMM by binding to specific microRNAs. Our results not only suggested that circRNAs might play critical roles in metastasis of OMM, but also provided critical information of circRNAs in regulating OMM progression. The findings would help us to develop potential biomarkers for clinical diagnosis and design therapeutic strategies for OMM.