KLK5 promotes anoikis resistance in non-small cell lung cancer by activating PI3K/AKT signaling pathway

Background Metastasis and recurrence remain the principal causes of mortality in non-small cell lung cancer (NSCLC) patients. A critical prerequisite for tumor cell invasion and metastasis is the development of resistance to anoikis. In NSCLC, high levels of KLK5 are linked to lymphatic metastasis and unfavorable patient survival. This study was designed to investigate the role of KLK5 in anoikis and hypothesized that KLK5 promotes NSCLC metastasis by conferring anoikis resistance via the PI3K/AKT pathway. Methods We established and characterized an anoikis-resistant stable cell line, AR-H1299. KLK5 expression in these cells was measured using RT-qPCR and Western blot. Functional assessments of AR-H1299 cells, including CCK-8 assay, colony formation assay, flow cytometry, wound healing assay, and Transwell assay, were performed, and the levels of epithelial-mesenchymal transition (EMT) and metastasis signaling-related proteins were examined. The mechanism by which KLK5 confers anoikis resistance was further investigated through Western blot analysis and functional rescue experiments. Results Our results show that KLK5 expression is closely associated with anoikis resistance in NSCLC cells. Genetic knockdown of KLK5 inhibited, while its overexpression enhanced, the proliferation, migration, invasion, and EMT process of AR-H1299 cells. Mechanistic studies revealed that KLK5 promotes the expression of downstream apoptotic regulators Bcl-2 and Bad by activating the PI3K/AKT pathway. Rescue experiments confirmed that the PI3K/AKT inhibitor LY294002 could counteract the pro-metastatic effects induced by KLK5 upregulation. Conclusion This study elucidates a previously unreported mechanism by which KLK5 confers anoikis resistance through the PI3K/AKT signaling pathway to promote metastasis in NSCLC.