Epstein–Barr virus (EBV) is a saliva-borne ɣ-herpesvirus associated with benign and malignant lymphoproliferation. EBV-mediated tumorigenic mechanisms are not fully understood and may be related to viral genetic variations. In this work, we characterize the genetic diversity of EBV from Brazil, assessing 82 samples derived from saliva from asymptomatic carriers (n = 45), biopsies of benign reactive hyperplasia (n = 4), and lymphomas (n = 33). Phylogenetic and phylogeographic analysis of the entire coding region of the LMP-1 was performed. Additionally, type 1/type 2 distinction by the EBNA3C gene and Zp variants were evaluated. Our results revealed a high diversity of EBV in Brazil, with the co-circulation of four main clades, described here as: Mediterranean (40.2%, n = 33), Raji/Argentine (39%, n = 32), B95-8 (6.1%, n = 5), and Asian II (1.2%, n = 1). The Raji/Argentine and Mediterranean clades were the most prevalent in South America (45% and 28%, respectively). The Raji/Argentine clade was associated with polymorphisms I124V/I152L, del30 bp, and ins15 bp (p < 0.0001, to all clades) and with a high haplotype diversity related to EBV type and Zp variants. We found that a Raji/Argentine subclade spread primarily from Brazil and later to other South American countries. Although no LMP1 variant has been directly associated with disease, the Raji/Argentine clade was predominantly clustered with lymphomas (61%) and the Mediterranean clade with non-malignant cases (59%) (p = 0.1). These data highlight the high genetic diversity of EBV circulating in Brazil, calling attention to a Raji-related variant with great recombination potential in Brazilian lymphomas.

Gastric cancer (GC) is an important cancer-related death worldwide. Among its histological subtypes, intestinal gastric cancer (IGC) is the most common. A previous work showed that increased expression of the THY1 gene was associated with poor overall survival in IGC. Furthermore, it was shown that IGC tumor cells with high expression of THY1 have a greater capacity for tumorigenesis and metastasis in vitro. This study aimed to identify molecular differences between IGC with high and low expression of THY1. Using a feature selection method, a group of 35 genes were found to be the most informative gene set for THY1^high IGC tumors. Through a classification model, these genes differentiate THY1^high from THY1^low tumors with 100% of accuracy both in the test subset and the independent test set. Additionally, this group of 35 genes correctly clustered 100% of the samples. An extensive validation of this potential molecular signature in multiple cohorts successfully segregated between THY1^high and THY1^low IGC tumors (>95%), proving to be independent of the gene expression quantification methodology. These genes are involved in central processes to tumor biology, such as the epithelial–mesenchymal transition (EMT) and remodeling of the tumor tissue composition. Moreover, patients with THY1^high IGC demonstrated poor survival and a more advanced clinicopathological staging. Our findings revealed a molecular signature for IGC with high THY1 expression. This signature showed EMT and remodeling of the tumor tissue composition potentially related to the biology of IGC. Altogether, our results indicate that THY1^high IGC tumors are a particular subset of tumors with a specific molecular and prognosis profile.

Background/Objectives: Chronic lymphocytic leukemia (CLL) is the most common adult leukemia in Western countries and it can progress to Richter’s syndrome (RS), a more aggressive condition. The NF-κB pathway is pivotal in CLL pathogenesis, driven mainly by B-cell receptor (BCR) signaling. However, recent evidence indicates that BCR signaling is reduced in RS, raising questions about whether and how NF-κB activity is maintained in RS. This study aims to elucidate the triggers and dynamics of NF-κB activation and the progression from CLL to RS. Methods: Integrated single-cell RNA sequencing data from peripheral blood samples of four CLL–RS patients were analyzed. NF-κB pathway activity and gene expression profiles were assessed to determine changes in NF-κB components and their targets. Tumor microenvironment composition and cell–cell communication patterns were inferred to explore NF-κB regulatory mechanisms. Results: RS samples showed increased proportions of malignant cells expressing NF-κB components, including NFKB1, NFKB2, RELA, IKBKG, MAP3K14, CHUK, and IKBKB, with significantly higher expression levels than in CLL. Enhanced NF-κB pathway activity in RS cells was associated with targets involved in immune modulation. The tumor microenvironment in RS displayed significant compositional changes, and signaling inference revealed enhanced cell–cell communication via BAFF and APRIL pathways, involving interactions with receptors such as BAFF-R and TACI on RS cells. Conclusions: The findings from this study reveal an active state of NF-κB in RS and suggest that this state plays a critical role in the evolution of CLL to RS, which is modulated by alternative signaling pathways and the influence of the tumor microenvironment.

Epstein–Barr virus (EBV) is a ubiquitous gammaherpesvirus etiologically associated with benign and malignant diseases. Since the pathogenic mechanisms of EBV are not fully understood, understanding EBV genetic diversity is an ongoing goal. Therefore, the present work describes the genetic diversity of the lytic gene BZLF1 in a sampling of 70 EBV-positive cases from southeastern Brazil. Additionally, together with the genetic regions previously characterized, the aim of the present study was to determine the impact of viral genetic factors that may influence EBV genetic diversity. Accordingly, the phylogenetic analysis of the BZLF1 indicated two main clades with high support, BZ-A and BZ-B (PP > 0.85). Thus, the BZ-A clade was the most diverse clade associated with the main polymorphisms investigated, including the haplotype Type 1 + V3 (p < 0.001). Furthermore, the multigene phylogenetic analysis (MLA) between BZLF1 and the oncogene LMP1 showed specific clusters, revealing haplotypic segregation that previous single-gene phylogenies from both genes failed to demonstrate. Surprisingly, the LMP1 Raji-related variant clusters were shown to be more diverse, associated with BZ-A/B and the Type 2/1 + V3 haplotypes. Finally, due to the high haplotypic diversity of the Raji-related variants, the number of DNA recombination-inducing motifs (DRIMs) was evaluated within the different clusters defined by the MLA. Similarly, the haplotype BZ-A + Raji was shown to harbor a greater number of DRIMs (p < 0.001). These results call attention to the high haplotype diversity of EBV in southeast Brazil and strengthen the hypothesis of the recombinant potential of South American Raji-related variants via the LMP1 oncogene.

Intestinal gastric cancer (IGC) carcinogenesis results from a complex interplay between environmental and molecular factors, ultimately contributing to disease development. We used integrative bioinformatic analysis to investigate IGC high-throughput molecular data to uncover interactions among differentially expressed genes, microRNAs, and proteins and their roles in IGC. An integrated network was generated based on experimentally validated microRNA-gene/protein interaction data, with three regulatory circuits involved in a complex network contributing to IGC progression. Key regulators were determined, including 23 microRNA and 15 gene/protein hubs. The regulatory circuit networks were associated with hallmarks of cancer, e.g., cell death, apoptosis and the cell cycle, the immune response, and epithelial-to-mesenchymal transition, indicating that different mechanisms of gene regulation impact similar biological functions. Altered expression of hubs was related to the clinicopathological characteristics of IGC patients and showed good performance in discriminating tumors from adjacent nontumor tissues and in relation to T stage and overall survival (OS). Interestingly, expression of upregulated hub hsa-mir-200b and its downregulated target hub gene/protein CFL2 were related not only to pathological T staging and OS but also to changes during IGC carcinogenesis. Our study suggests that regulation of CFL2 by hsa-miR-200b is a dynamic process during tumor progression and that this control plays essential roles in IGC development. Overall, the results indicate that this regulatory interaction is an important component in IGC pathogenesis. Also, we identified a novel molecular interplay between microRNAs, proteins, and genes associated with IGC in a complex biological network and the hubs closely related to IGC carcinogenesis as potential biomarkers.

Gastric cancer (GC) remains one of the leading causes of cancer-related mortality worldwide, with high molecular heterogeneity contributing to its poor prognosis. Among potential biomarkers, THY1 is associated with aggressive tumor behavior and poor patient outcomes. However, the transcriptional mechanisms governing THY1 expression in GC remain largely unexplored. This study aimed to systematically investigate the upstream regulatory landscape of THY1 and its role in tumor progression. By integrating multicohort transcriptomic data (n = 945), we inferred consensus transcriptional regulatory networks (TRNs) and identified six putative transcription factors (PRRX1, TWIST1, SNAI2, MEIS3, VENTX, and EGR2) as robust regulators of THY1. The functional enrichment analysis revealed that these regulators are involved in the epithelial–mesenchymal transition (EMT) and extracellular matrix remodeling, key processes associated with tumor invasion and metastasis. Experimental validation using chromatin immunoprecipitation (ChIP) assays indicated the direct and differential binding of TWIST1 and SNAI2 to the THY1 promoter, supporting their roles as key regulators of THY1 expression in GC. Our findings provide a mechanistic link between THY1 expression and EMT transcriptional programs, offering insights into its association with a poor prognosis. By integrating bioinformatic predictions with experimental demonstration, this study not only improves our understanding of THY1 regulation but also provides a framework for dissecting the transcriptional networks governing aggressive tumor phenotypes. These results contribute to a broader understanding of GC progression and may inform future therapeutic strategies targeting EMT-related pathways in THY1^high GC.