PLK1-mediated phosphorylation of 13-catenin enhances its stability and transcriptional activity for extracellular matrix remodeling in metastatic NSCLC
Rationale: 13-catenin is a component for cell adhesion and a transcriptional coactivator in epithelial-mesenchymal transition (EMT). Previously we found that catalytically active PLK1 drives EMT in non-small cell lung cancer (NSCLC), upregulating extracellular matrix factors including TSG6, laminin y2, and CD44. To understand the underlying mechanism and clinical significance of PLK1 and 13-catenin in NSCLC, their relationship and function in metastatic regulation were investigated.Methods: The clinical relevance between the survival rate of NSCLC patients and the expression of PLK1 and 13-catenin was analyzed by a KM plot. Immunoprecipitation, kinase assay, LC-MS/MS spectrometry, and site-directed mutagenesis were performed to reveal their interaction and phosphorylation. A lentiviral doxycycline-inducible system, Transwell-based 3D culture, tail-vein injection model, confocal microscopy, and chromatin immunoprecipitation assays were used to elucidate the function of phosphorylated 13-catenin in the EMT of NSCLC.Results: Clinical analysis revealed that the high expression of CTNNB1/PLK1 was inversely correlated with the survival rates of 1,292 NSCLC patients, especially in metastatic NSCLC. In TGF-13-induced or active PLK1-driven EMT, 13-catenin, PLK1, TSG6, laminin y2, and CD44 were concurrently upregulated. 13-catenin is a binding partner of PLK1 in TGF-13-induced EMT and is phosphorylated at S311. Phosphomimetic 13-catenin promotes cell motility, invasiveness of NSCLC cells, and metastasis in a tail-vein injection mouse model. Its upregulated stability by phosphorylation enhances transcriptional activity through nuclear translocation for the expression of laminin y2, CD44, and c-Jun, therefore enhancing PLK1 expression by AP-1.Conclusions: Our findings provide evidence for the critical role of the PLK1/beta-catenin/AP-1 axis in metastatic NSCLC, implying that 13-catenin and PLK1 may serve as a molecular target and prognostic indicator of the therapeutic response in metastatic NSCLC patients.
Web of Science Categories
Medicine, Research & Experimental
Funding
Basic Science Research Program through the National Research Foundation of Korea (NRF) - Ministry of Education, Science and Technology [NRF-2017R1A2B2012301, NRF-2020R1A2C2008672]