Long Noncoding RNA MRPL23-AS1 Promotes Adenoid Cystic Carcinoma Lung Metastasis

Lung metastasis is a major factor affecting long-term survival in patients with adenoid cystic carcinoma. Here, we showed that the long noncoding RNA (lncRNA) MRPL23 antisense RNA 1 (MRPL23-AS1) was highly expressed and correlated with lung metastasis and overall survival in patients with salivary adenoid cystic carcinoma (SACC). MRPL23-AS1 positively regulated epithelial-mesenchymal transition by forming an RNA-protein complex with enhancer of zeste homolog 2 (EZH2). MRPL23-AS1 increased the binding of EZH2 and H3K27me3 on the E-cadherin promoter region. Moreover, MRPL23-AS1 levels were higher in exosomes isolated from the blood plasma of patients with SACC, and exosomal MRPL23-AS1 affected pulmonary microvascular endothelial cells in an "exosomecrine" manner. MRPL23-AS1-enriched exosomes increased microvascular permeability and facilitated the metastasis of SACC in vivo. Collectively, these findings highlight a molecular mechanism of lung metastasis in SACC. MRPL23-AS1 may represent a biomarker and target for clinical intervention to control this intractable disease. SIGNIFICANCE: This study identifies a novel metastasis-promoting lncRNA MRPL23-AS1, which mediates the transcriptional silencing of E-cadherin through forming an RNA-protein complex with EZH2.