Long Noncoding RNA MSL3P1 Regulates CUL3 mRNA Cytoplasmic Transport and Stability and Promotes Lung Adenocarcinoma Metastasis

Lung adenocarcinoma (LUAD) is the most prevalent histological type of lung cancer. Previous studies have reported that specific long noncoding RNAs (lncRNA) are involved in cancer development and progression. The phenotype and mechanism of ENST00000440028, named MSL3P1, an lncRNA referred to as a cancer-testis gene with potential roles in tumorigenesis and progression, have not been reported. MSL3P1 is overexpressed in LUAD tumor tissues, which is significantly associated with clinical characteristics, metastasis, and poor clinical prognosis. MSL3P1 promotes the metastasis of LUAD in vitro and in vivo. The enhancer reprogramming in LUAD tumor tissue is the major driver of the aberrant expression of MSL3P1. Mechanistically, owing to the competitive binding to CUL3 mRNA with ZFC3H1 protein (a protein involved in targeting polyadenylated RNA to exosomes and promoting the degradation of target mRNA), MSL3P1 can prevent the ZFC3H1-mediated RNA degradation of CUL3 mRNA and transport it to the cytoplasm. This activates the downstream epithelial-to-mesenchymal transition signaling pathway and promotes tumor invasion and metastasis. Implications: This study indicates that lncRNA MSL3P1 regulates CUL3 mRNA stability and promotes metastasis and holds potential as a prognostic biomarker and therapeutic target in LUAD.