Cervantes-Gracia, K. | Search bioRxiv

bioRxiv2024

Melanoma Response to Immunotherapy is regulated by B Cell-Derived Extracellular Vesicles

The immune tumor microenvironment (TME) is increasingly recognized as a dynamic ecosystem where B cells play pivotal roles in modulating therapeutic responses, particularly in the context of immune checkpoint blockade (ICB) therapy. While B cells have traditionally been viewed as bystanders in tumor immunity, recent evidence suggests they may actively influence anti-tumor immunity, albeit with conflicting reports regarding their pro-tumor or anti-tumor roles. This study explores the crucial roles played by B cells and their secreted extracellular vesicles (EVs) in shaping melanoma responses to ICB therapy. We show a significant enrichment of B cells in ICB therapy responders compared to non-responders, pre-treatment, through retrospective analyses of melanoma patient tumors. Functional assays demonstrate that B cell depletion impairs T cell-mediated tumor cytotoxicity, underscoring the importance of B cells in anti-tumor responses. To investigate the clinical relevance, EVs were isolated from melanoma patient tumors, and fractioned into tumor and immune subpopulations. MiRNA profiling of CD19+ EVs identifies miR-99a-5p as a top candidate, among several others, upregulated in responders. Functional assays show that miR-99a-5p silencing in B cells diminishes T cell-mediated anti-tumor activity, suggesting its role in promoting B cell-mediated immune responses. Mechanistically, miR-99a-5p influences B cell maturation within the TME by mediating class-switch recombination. Our findings highlight the important role of B cells and their derived EVs in shaping the efficacy of melanoma immunotherapy, paving the way for novel therapeutic strategies targeting B cell-related pathways. Graphical abstract (created with Biorender) O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=177 SRC="FIGDIR/small/628150v1_ufig1.gif" ALT="Figure 1"> View larger version (60K): org.highwire.dtl.DTLVardef@144bbe6org.highwire.dtl.DTLVardef@18c1e9eorg.highwire.dtl.DTLVardef@2e37aaorg.highwire.dtl.DTLVardef@487e18_HPS_FORMAT_FIGEXP M_FIG C_FIG

cancer biology↗

bioRxiv2021

Modelling liver cancer microenvironment: novel 3D culture system as a potential anti-cancer drug screening tool

The tumor microenvironment and its contribution to tumorigenesis has been a focal highlight in recent years. A two-way communication between the tumor and the surrounding microenvironment sustains and contributes to the growth and metastasis of tumors. Progression and metastasis of hepatocellular carcinoma have been reported to be exceedingly influenced by diverse microenvironmental cues. In this study, we present a 3D-culture model of liver cancer to better mimic in vivo tumor settings. By creating novel 3D co-culture model that combines free-floating and scaffold based 3D-culture techniques of liver cancer cells and fibroblasts, we aimed to establish a simple albeit reproducible ex vivo cancer microenvironment model that captures tumor-stroma interactions. The model presented herein exhibited unique gene expression and protein expression profiles when compared to 2D and 3D mono-cultures of liver cancer cells. Our results showed that in vivo like conditions cannot be mimicked by simply growing cancer cells as spheroids, but by co-culturing them with 3D fibroblast with which they were able to cross-talk. This was evident by the upregulation of several pathways involved in HCC, and the increase in secreted factors by co-cultured cancer cells, many of which are also involved in tumor-stroma interactions. Compared to the conventional 2D culture, the proposed model exhibits an increase in the expression of genes associated with development, progression, and poor prognosis of HCC. Our results correlated with an aggressive outcome that better mirrors in vivo HCC, and therefore, a more reliable platform for molecular understanding of HCC and possibly better anti-cancer drug screening.

cancer biology↗