Dauriporphine Inhibits NSCLC Growth and Stemness by Targeting USP7/CASK Pathway

Introduction and Rationale

Dauriporphine is an aporphine monomer extracted from Menispermum dauricum DC that has demonstrated anti-cancer effects in non-small cell lung cancer (NSCLC). The molecular mechanisms underlying its activity were incompletely characterized. This study aimed to identify the molecular targets and pathways through which dauriporphine exerts anti-tumor effects in NSCLC cells and in vivo models.

In vitro assays and phenotypic effects of dauriporphine on NSCLC

Multiple cellular assays were used to evaluate dauriporphine’s impact on NSCLC cell behaviors. Cell viability was measured with the cell counting kit-8 (CCK-8) assay and proliferation assessed via ethynyl-2'-deoxyuridine (EdU) incorporation. Apoptosis was analyzed by flow cytometry. Invasive and migratory capacities were tested using transwell and scratch assays, respectively. Tumor stemness was evaluated with sphere formation assays.

Dauriporphine treatment restrained NSCLC cell proliferation, invasion, migration, and stemness with statistical significance (p < 0.05). The compound therefore affected multiple malignant phenotypes relevant to tumor growth and metastatic potential.

Bioinformatics and WGCNA identification of CASK

To identify candidate molecular targets of dauriporphine in NSCLC, the investigators combined bioinformatics analyses with weighted gene co-expression network analysis (WGCNA). These approaches highlighted calcium/calmodulin-dependent serine protein kinase (CASK) as a core target linked to the compound’s activity in NSCLC.

Expression of CASK in NSCLC samples and cells

Analysis of clinical samples and NSCLC cell lines found that CASK was up-regulated in NSCLC (p < 0.05). Experimental reduction of CASK expression was associated with the anti-cancer effects of dauriporphine in NSCLC cells (p < 0.05), supporting a functional role for CASK in promoting malignant phenotypes.

USP7–CASK interaction and ubiquitination regulation

The study examined the regulatory relationship between ubiquitin-specific protease 7 (USP7) and CASK. Co-immunoprecipitation experiments demonstrated interaction between USP7 and CASK, and assays of ubiquitination indicated that USP7 stabilized CASK protein by inducing deubiquitination (p < 0.05). This identifies a post-translational mechanism by which CASK protein levels can be maintained in NSCLC cells.

Genetic modulation of USP7 and effects on NSCLC phenotypes

Silencing of USP7 reduced NSCLC cell proliferation, metastatic behaviors, and stemness through inhibition of CASK (p < 0.05). These genetic studies position USP7 upstream of CASK in a regulatory axis that supports NSCLC malignant characteristics, indicating that targeting USP7 can phenocopy the effects of CASK inhibition.

Dauriporphine interaction with USP7 and rescue experiments

Biochemical analysis showed that dauriporphine interacted with USP7. Functionally, overexpression of USP7 reversed the inhibitory effects of dauriporphine on malignant cell behaviors (p < 0.05), demonstrating that USP7 activity is required for maintaining the NSCLC phenotypes that dauriporphine suppresses. This supports the interpretation that dauriporphine’s anti-tumor effect occurs, at least in part, via modulation of USP7 activity.

In vivo xenograft findings

The authors evaluated dauriporphine in a xenograft tumor model. Dauriporphine treatment reduced tumor growth in vivo and was associated with down-regulation of USP7 and CASK expression in tumor tissue (p < 0.05). These in vivo results align with the in vitro findings and support the translational relevance of the USP7–CASK axis as a mediator of dauriporphine’s anti-tumor activity.

Proposed mechanism and therapeutic implications

Collectively, the data indicate that dauriporphine blocks key malignant phenotypes of NSCLC cells by inhibiting USP7-mediated deubiquitination of CASK, thereby promoting CASK proteasomal degradation. By reducing CASK protein stability, dauriporphine suppresses proliferation, invasion, migration, and stemness in NSCLC models. The study proposes USP7 and CASK as potential molecular targets for dauriporphine-based therapeutic strategies in NSCLC.

Limitations and details not reported

The abstract reports significant findings across multiple assays and an in vivo xenograft model, but it does not provide full experimental details in this summary. Specific data points such as exact effect sizes, concentrations of dauriporphine used in each assay, numbers of biological replicates, animal model parameters, and full statistical reporting beyond p < 0.05 are not specified in the abstract and therefore are not reported here. Additional methodological and quantitative details would be available in the full published article.

Clinical and research takeaways

• Dauriporphine demonstrates multi-faceted anti-NSCLC activity in preclinical models by targeting a post-translational regulatory axis (USP7 → deubiquitination → CASK stabilization).
• Targeting deubiquitinases such as USP7 to destabilize oncogenic proteins (here, CASK) represents a mechanistic approach supported by both in vitro and in vivo data in this study.
• The findings warrant further preclinical investigation into dosing, pharmacokinetics, safety, and efficacy, and justify mechanistic follow-up in more detailed studies to assess translational potential.