MYL9 binding with MYO19 suppresses epithelial-mesenchymal transition in non-small-cell lung cancer

The elusive function of myosin light chain 9 (MYL9) in cancer is an area ripe for further investigation. Bioinformatics was used to compare the expression levels of MYL9 in non-small-cell lung cancer (NSCLC) and normal tissues. Gene set enrichment analysis was used to investigate the pathways associated with MYL9. The BioGRID database was used to screen for potential targets of MYL9. The expression of MYL9 and myosin 19 (MYO19) mRNA was quantified using quantitative reverse transcriptase PCR. Cell migration was assessed using a scratch wound healing assay. The protein levels of MYL9, MYO19, and epithelial-mesenchymal transition (EMT) biomarkers were examined using Western blot (WB). Epithelial cell adhesion molecule (EpCAM) expression in different cell groups was profiled using flow cytometry analysis. Coimmunoprecipitation assays were performed to determine the binding affinity between MYL9 and MYO19. In addition, the direct protein interaction between MYL9 and MYO19 was explored using a glutathione-S-transferase (GST) pull-down assay. In NSCLC patients, MYL9 was significantly downregulated both in vivo and in cell cultures and had a high enrichment score in the EMT pathway. Scratch assays pointed to its inhibitory effect on cancer cell migration. WB showed that MYL9 could suppress EMT marker protein expression in NSCLC cells. Flow cytometry found that MYL9 greatly reduced the distribution of EpCAM on the cell surface. MYO19 was pinpointed as a potential target of MYL9, as confirmed by coimmunoprecipitation and GST pull-down assays. Rescue experiments confirmed that MYO19 could enhance cell migration, promote the expression of EMT markers, and increase EpCAM levels on the cell surface, but these effects were reserved by MYL9 overexpression. MYL9 impedes the migration and EMT in NSCLC cells by binding to MYO19.<b>NEW & NOTEWORTHY</b> Myosin light chain 9 (MYL9) is downregulated in non-small-cell lung cancer (NSCLC). MYL9 suppresses epithelial-mesenchymal transition (EMT) in NSCLC cells. MYL9 binds to myosin 19 (MYO19). MYL9/MYO19 signaling inhibits EMT in NSCLC.