Unveiling the PDK4-centered rituximab-resistant mechanism in DLBCL: the potential of the "Smart" exosome nanoparticle therapy.

BACKGROUND: Diffuse large B-cell lymphoma (DLBCL) represents a prevalent malignant tumor, with approximately 40% of patients encountering treatment challenges or relapse attributed to rituximab resistance, primarily due to diminished or absent CD20 expression. Our prior research identified PDK4 as a key driver of rituximab resistance through its negative regulation of CD20 expression. Further investigation into PDK4's resistance mechanism and the development of advanced exosome nanoparticle complexes may unveil novel resistance targets and pave the way for innovative, effective treatment modalities for DLBCL. METHODS: We utilized a DLBCL-resistant cell line with high PDK4 expression (SU-DHL-2/R). We infected it with short hairpin RNA (shRNA) lentivirus for RNA sequencing, aiming to identify significantly downregulated mRNA in resistant cells. Techniques including immunofluorescence, immunohistochemistry, and Western blotting were employed to determine PDK4's localization and expression in resistant cells and its regulatory role in phosphorylation of Histone deacetylase 8 (HDAC8). Furthermore, we engineered advanced exosome nanoparticle complexes, aCD20@ExoCTX/siPDK4, through cellular, genetic, and chemical engineering methods. These nanoparticles underwent characterization via Dynamic Light Scattering (DLS) and Transmission Electron Microscopy (TEM), and their cellular uptake was assessed through flow cytometry. We evaluated the nanoparticles' effects on apoptosis in DLBCL-resistant cells and immune cells using CCK-8 assays and flow cytometry. Additionally, their capacity to counteract resistance and exert anti-tumor effects was tested in a resistant DLBCL mouse model. RESULTS: We found that PDK4 initiates HDAC8 activation by phosphorylating the Ser-39 site, suppressing CD20 protein expression through deacetylation. The aCD20@ExoCTX/siPDK4 nanoparticles served as effective intracellular delivery mechanisms for gene therapy and monoclonal antibodies, simultaneously inducing apoptosis in resistant DLBCL cells and triggering immunogenic cell death in tumor cells. This dual action effectively reversed the immunosuppressive tumor microenvironment, showcasing a synergistic therapeutic effect in a subcutaneous mouse tumor resistance model. CONCLUSIONS: This study demonstrates that PDK4 contributes to rituximab resistance in DLBCL by modulating CD20 expression via HDAC8 phosphorylation. The designed exosome nanoparticles effectively overcome this resistance by targeting the PDK4/HDAC8/CD20 pathway, representing a promising approach for drug delivery and treating patients with Rituximab-resistant DLBCL.

Combination therapy of targeting CD20 antibody and immune checkpoint inhibitor may be a breakthrough in the treatment of B-cell lymphoma.

Background: CD20 is a membrane protein extensively expressed on the surface of B cells at various stages of development and differentiation. Herein, we conducted a bibliometrics analysis of the literature on CD20-targeting antibody therapy in lymphoma. Methods: A total of 6663 articles were downloaded from the web of science core collection (WOSCC) from 1999 to July 23, 2022. Bibliometric.com was used for citation and annual publications analysis. VOSviewer was used to map countries/institutions/authors/journals nodes and links, extract hotspot keywords, and analyze the time trend of keywords. Citespace was employed to recognize the turning points based on the centrality value of countries, define the topic distribution of academics according to the map of dual-map overlay of journals, and characterize the emerging topics or landmark articles in a field based on references citation bursts. Results: All articles were cited 225,032 times, averaging 33.77. The number of articles increased from 1999 to 2002, while the growth rate entered the platform after 2002. The USA was the most publication country, and China was the largest emerging country. Hotspots in this field still focus on the efficacy of rituximab in treating non-Hodgkin's lymphoma and the pathogenesis of lymphoma Application of generation CD-20 antibodies or molecule inhibitors in clinical research and cellular therapy/immunotherapy, such as CAR-T and PDL1/PD1 were the emerging research topics. Conclusion: This study provides essential information and the tendency of the CD20-targeting antibody therapy in lymphoma by using bibliometric and visual methods, which would provide helpful references for clinical experiments and basic scientific research.