Comparison of miRNA Profiles of Primary Tumors and Metastatic Tumors of Salivary Gland Tumors and Their Role in Prognosis: A Systematic Review.

Background: MicroRNAs (miRNAs) are implicated in several biological processes, such as control of tissue homeostasis, cell signaling, differentiation, proliferation, neoplastic transformation, and activation/inhibition of apoptotic mechanisms. In this systematic review, we evaluated the changes in the expression pattern of miRNAs in salivary gland tumors (SGTs).

Methods: A comprehensive search was conducted in PubMed, and Scopus with no language and date restrictions in Feb 2023. All the studies on SGTs that evaluated miRNA profiling were included. Relevant data regarding the overexpression and down-regulation of the miRNAs were extracted. The quality of the included studies was evaluated with Newcastle-Ottawa checklist. The altered expression of miRNAs was evaluated between SGTs and normal cases, benign and malignant tumors, and primary and high-grade tumors.

Results: Thirteen studies were included in this systematic review. There were considerable differences between malignant and benign tumors regarding the miRNAs expression level. In the five studies, the miRNA profile of the primary tumors was compared with metastatic tumors to reveal the involvement of the miRNA in the prognosis of the salivary tumors. The miRNAs expression changes were correlated with tumor size, stage, recurrence, and occurrence of solid components. Perineural invasion and lymph node metastasis were also reported in ACCLM cell line and recurrence of adenoid cystic carcinoma (ACC) tissues.

Conclusion: The miRNA profiling confirms their prognostic value in salivary gland tumors. Significant alternations of the miRNAs expression are useful for distinguishing different types of salivary tumors and malignant tumors from benign types. The miRNA expression changes also affect the prognosis of salivary tumors.