Dauriporphine Suppresses Cell Proliferation, Metastasis, and Stemness of Non-Small Cell Lung Cancer Through the Regulation of the USP7/CASK.

Dauriporphine is a monomer extracted from Menispermum dauricum DC, and it exhibits anti-cancer effect in non-small cell lung cancer (NSCLC). The regulatory mechanism of dauriporphine remains incompletely understood, and this study focused on its molecular targets in NSCLC progression. Cell viability, proliferation, apoptosis, invasion, migration, and stemness were evaluated using cell counting kit-8, ethynyl-2'-deoxyuridine assay, flow cytometry, transwell assay, scratch assay, and sphere formation assay, respectively. Bioinformatics analysis and weighted gene co-expression network analysis (WGCNA) were performed to identify targets of dauriporphine in NSCLC. The mRNA and protein expression was quantified using qPCR and Western blot. Co-immunoprecipitation was used to analyze protein interaction and ubiquitination regulation between ubiquitin-specific protease 7 (USP7) and calcium/calmodulin-dependent serine protein kinase (CASK). The role of dauriporphine in vivo was explored using xenograft tumor model. Dauriporphine restrained proliferation, invasion, migration, and stemness of NSCLC cells (p < 0.05). Bioinformatics analysis and WGCNA identified CASK as a core target of dauriporphine in NSCLC. CASK was highly up-regulated in NSCLC samples and cells (p < 0.05). Anti-cancer effects of dauriporphine on NSCLC cells were associated with reduced CASK expression (p < 0.05). USP7 stabilized CASK protein by inducing deubiquitination (p < 0.05). Silencing USP7 restrained NSCLC cell proliferation, metastasis, and stemness by inhibiting CASK (p < 0.05). Dauriporphine interacted with USP7, and then USP7 overexpression reversed the inhibition of dauriporphine in NSCLC cell malignant behaviors (p < 0.05). Dauriporphine reduced tumor growth in vivo and down-regulated USP7 and CASK expression (p < 0.05). This study suggested that dauriporphine blocked the key malignant phenotypes of NSCLC cells via inhibiting USP7-mediated deubiquitination of CASK, thereby promoting its proteasomal degradation. The study elucidates a molecular mechanism underlying anti-tumor role of dauriporphine and providing potential targets for dauriporphine treatment.