Impact of liquid-liquid phase separation- and immune-related gene signatures on multiple myeloma prognosis: focus on DDX21 and EZH2.

Objective: Liquid-liquid phase separation (LLPS) may affect the therapeutic sensitivity of multiple myeloma (MM). This study aimed to identify LLPS-related genes with MM prognostic values and to confirm their effects on tumor progression.

Methods: Based on public transcriptomic data, this study screened LLPS- and immune-related genes for MM-derived plasma cells. Subtypes were identified using consensus clustering, followed by comparisons using t-test and survival analysis. Least absolute shrinkage and selection operator was implemented to screen prognostic signatures, and Kaplan-Meier and receiver operator characteristic curves were plotted to assess their prognostic values. After transfected with sh-DDX21, CCK8, flow cytometry, and Transwells were used to observe MM cell proliferation, apoptosis, migration, and invasion.

Results: By overlapping LLPS- and immune-related genes, 103 genes were obtained to cluster MM samples into three subtypes, which had significant differences in survival and immune landscape. Cox regression analysis screened out EZH2 and DDX21 that significantly overexpressed in MM to construct a prognostic model, with superior performance in predicting MM prognostic risks. Notably, subtype2 with more adverse prognosis showed significantly elevated risk scores and was more distributed in groups with high prognostic risk. In vitro experiments confirmed that cell proliferation, invasion, and migration were significantly inhibited in MM.1S cells transfected with sh-DDX21.

Conclusion: LLPS-related EZH2 and DDX21 were novel markers to predict prognostic risk of MM. Among them, DDX21 was experimentally confirmed to promote MM cell proliferation, migration and invasion. These potential prognostic markers could be targeted in future personalized therapeutic strategies for MM, potentially improving patient outcomes.