# Tumor-derived exosomal miR-199b-5p promotes proliferation and epithelial-mesenchymal transition in non-small cell lung cancer by targeting CCNL1

## TL;DR

This study shows that exosomal miR-199b-5p from lung cancer cells promotes cancer growth and spread by targeting CCNL1 and activating the Wnt/β-catenin pathway.

## Contribution

The novel finding is that miR-199b-5p promotes lung cancer progression via CCNL1 and the Wnt/β-catenin signaling pathway.

## Key findings

- Exosomal miR-199b-5p enhances lung cancer cell proliferation and epithelial-mesenchymal transition (EMT).
- miR-199b-5p targets CCNL1 and activates the Wnt/β-catenin signaling pathway in lung cancer cells.
- Exosomes from SK-LU-1 cells with high miR-199b-5p levels promote metastasis and inhibit CCNL1 expression.

## Abstract

•MiR-199b-5p showed the highest expression level in SK-LU-1 cells and its exosomes.•Overexpression of miR-199b-5p promotes lung cancer cell proliferation, migration, and EMT.•The underlying mechanism of miR-199b-5p was related to CCNL1.

MiR-199b-5p showed the highest expression level in SK-LU-1 cells and its exosomes.

Overexpression of miR-199b-5p promotes lung cancer cell proliferation, migration, and EMT.

The underlying mechanism of miR-199b-5p was related to CCNL1.

To explore the effect of exosome-mediated miR-199b-5p on lung cancer cells behavior, intrapulmonary metastasis, and its underlying mechanism.

Exosomes from SK-LU-1 cells overexpressing has-miR-199b-5p (miR-199b-5p) were used to treat A549 or H299 cells. Cell motility was evaluated using wound scratch healing and transwell assays. Gene and protein expression were detected by quantitative real-time PCR (QRT-PCR) and Western blot. Target genes of miR-199b-5p were predicted through multiple-database analysis and validated.

Transmission electron microscopy (TEM) demonstrated isolated exosomes had a typical bilayer membrane (30-100 nm). miR-199b-5p was highly expressed in lung cancer cells and detectable in the serum of lung cancer patients, with the highest levels observed in SK-LU-1 cells and their derived exosomes. Exosomal miR-199b-5p significantly enhanced the motility of A549 and H1299 cells and upregulated the expression of epithelial-mesenchymal transition (EMT)-related proteins. Exosomes promoted lung metastasis of H1299 cells and inhibited the expression of Cyclin L1 (CCNL1). Either CCNL1 inhibition or miR-199b-5p overexpression significantly promoted H1299 cell proliferation and reduced apoptosis, while CCNL1 overexpression inhibited cell motility. Protein-protein interaction (PPI) network, Gene Ontology (GO), and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analyses indicated involvement of the Wnt/β-catenin signaling pathway in the downstream mechanism. Mechanistically, miR-199b-5p inhibited cyclin-dependent kinase 11 (CDK11) and upregulated the expression of transcription factor 4 (TCF-4) and β-catenin.

Overexpression of miR-199b-5p promotes proliferation, migration, and EMT in lung cancer cells by targeting CCNL1, with its downstream regulatory effects mediated through the Wnt/β-catenin signaling.