Characterization of a novel lncRNA RP3-340N1.2 and its association with a miR-4650-5p/SHC1-related regulatory network in lung adenocarcinoma
by Fang Chen, Yan Yan, Wenting Yang, Zhilin Li, Daying Wang, Jianqiao Huang, Chaozhou Wan, Tingting An, Li Tong, Maoxia Ran, Yaqiong Dong, Yunfen Chen Long noncoding RNAs (lncRNAs) are increasingly recognized as regulators of cancer-related biological processes. However, the functional significance of many lncRNAs in lung adenocarcinoma (LUAD) remains incompletely understood. In this study, we identified RP3-340N1.2 as an upregulated lncRNA in LUAD through analyses of public transcriptomic datasets, which was further confirmed by quantitative real-time PCR in LUAD cell lines. Functional assays demonstrated that knockdown of RP3-340N1.2 was associated with reduced proliferation, migration, invasion, and clonogenic growth of LUAD cells in vitro. In addition, suppression of RP3-340N1.2 attenuated tumor growth in a xenograft model. Bioinformatic analysis using the LncBase Experimental v3 database identified hsa-miR-4650-5p as a potential interacting microRNA of RP3-340N1.2. This interaction was further examined by dual-luciferase reporter and RNA immunoprecipitation assays. Functional experiments additionally showed that miR-4650-5p overexpression was associated with reduced proliferative and migratory capacities in LUAD cells. Among the predicted downstream targets of miR-4650-5p, SHC1 was selected for further investigation. Alterations in RP3-340N1.2 or miR-4650-5p expression were accompanied by corresponding changes in SHC1 expression and ERK1/2 phosphorylation. Furthermore, rescue experiments demonstrated that SHC1 knockdown largely reversed RP3-340N1.2-associated cellular phenotypes, supporting the functional involvement of SHC1 within this regulatory framework. Collectively, these findings indicate that RP3-340N1.2 is aberrantly expressed in LUAD and may participate in tumor-associated cellular behaviors through a miR-4650-5p/SHC1-related regulatory mechanism. This study provides preliminary evidence supporting the potential relevance of RP3-340N1.2 in LUAD and offers additional insight into lncRNA-associated regulatory networks in this disease.