This study began with a transcriptomic analysis of the The Cancer Genome Atlas (TCGA) mesothelioma cohort to map immune-regulatory ligand expression across tumour subtypes. The authors report that VISTA and B7-H3 are highly expressed in mesothelioma samples. Expression patterns for these molecules correlated with gene sets associated with distinct histologic subtypes: VISTA expression aligned with genes highly expressed in epithelioid cells, whereas B7-H3 expression correlated with genes characteristic of sarcomatoid cells. These observations motivated functional investigation of VISTA in mesothelioma cells.
To determine whether VISTA affects tumour cell behaviour directly, the investigators manipulated VISTA expression in mesothelioma cell lines. Overexpression of VISTA increased proliferation in these cell lines, while targeted knockdown of VISTA produced a marked suppression of cell growth in vitro. The reported findings indicate that VISTA modulates proliferative capacity of mesothelioma cells independent of any described immune-mediated effects.
The authors used immunoprecipitation–mass spectrometry (IP–MS) to define proteins that physically associate with VISTA in mesothelioma cells. Proteomic profiling revealed interactions between VISTA and multiple proteins, including cell adhesion molecules and intracellular signalling components. Among the intracellular interactors identified was receptor-interacting serine/threonine-protein kinase 1 (RIPK1). These associations provide candidate mechanisms by which membrane-associated VISTA could influence intracellular signalling networks that regulate proliferation.
RNA sequencing (RNA-seq) was performed to characterise downstream transcriptional changes linked to VISTA expression. Differential expression analysis revealed enrichment of TNF signalling pathways among the genes altered by VISTA manipulation. The transcriptomic signature associated with VISTA changes supports the proteomic findings and points to activation of inflammatory and survival-related pathways that can influence cell proliferation.
Functional assays assessing intracellular signalling demonstrated enhanced phosphorylation of protein kinase B (AKT) in association with VISTA expression. Increased AKT phosphorylation is consistent with activation of growth and survival signalling cascades, providing a plausible mechanistic link between membrane-localised VISTA, its identified intracellular interactors, and enhanced proliferative phenotype. The combined proteomic, transcriptomic and signalling data support a model in which VISTA engages adhesion and signalling partners to activate AKT-dependent pathways that promote tumour-intrinsic proliferation.
The study extended in vitro observations to an in vivo context using a mouse xenograft model. Tumours derived from mesothelioma cells with VISTA knockdown exhibited markedly suppressed growth compared with controls. These in vivo results corroborate the cell-line data and indicate that VISTA contributes to tumour growth in an organismal setting, again consistent with a tumour-intrinsic role rather than a solely immune-mediated effect.
The authors conclude that VISTA promotes mesothelioma cell proliferation through tumour-intrinsic signalling mechanisms that include interactions with cell adhesion molecules, engagement of RIPK1-associated complexes, enrichment of TNF signalling transcripts, and enhancement of AKT phosphorylation. Importantly, these effects were observed in cell lines and in a xenograft model, supporting the concept that VISTA functions within tumour cells to modulate growth. Based on these data, the authors propose that VISTA represents a promising subtype-specific therapeutic target for mesothelioma, particularly in contexts where VISTA is highly expressed.
The RNA-seq datasets generated in this study are deposited in the NCBI Sequence Read Archive (SRA) under accession PRJNA1418830. The IP–MS data are deposited in the Japan ProteOme STandard Repository/Database (jPOST) via ProteomeXchange under the dataset identifier JPST004202. The article states that additional datasets and materials are available from the corresponding author upon reasonable request.
Figures referenced in the source illustrate: TCGA-based VISTA expression analysis (Fig. 1); in vitro suppression of proliferation after VISTA knockdown (Fig. 2); results of IP–MS identifying VISTA-associated proteins (Fig. 3); gene expression changes and AKT-related signalling modulation (Fig. 4); and suppressed tumour growth in vivo following VISTA knockdown (Fig. 5). The source text is a subscription article in the British Journal of Cancer and provides these primary data and deposit identifiers as the basis for the conclusions.