MicroRNAs: Potential diagnostic markers and therapeutic targets for EBV-associated nasopharyngeal carcinoma

Nasopharyngeal carcinoma (NPC) is a highly malignant cancer with local invasion and early distant metastasis. NPC is highly prevalent in the Southern China and South-eastern Asia. The genetic susceptibility, endemic environment factors, and Epstein-Barr virus (EBV) infection are believed to be the major etiologic factors of NPC. Once metastasis occurs, the prognosis is very poor. It is urgently needed to develop biomarkers for early clinical diagnosis/prognosis, and novel effective therapies for nasopharyngeal carcinoma. In this paper, we systematically reviewed the current progress of miRNA studies in NPC. It has been shown that both host encoded miRNAs and EBV encoded miRNAs play key roles in almost all the steps of epithelia cell carcinogenesis, including epithelial-mesenchymal to stem-like transition, cell growth, migration, invasion, and tumorigenesis. More importantly, some miRNAs could be secreted out and play a role in the microenvironments. The level of sera miRNAs is correlated with the copy numbers of host miRNAs in tumor biopsies. Promising results of gene therapy have been also achieved by lentiviral delivered miRNAs. Taken together, cell free miRNAs would be potential biomarkers of early clinical diagnosis/prognosis; while some miRNAs could be further developed into therapeutic agents in the future.