New study reveals E2F and CREB as a novel therapeutic option for testicular DLBCL patients

Primary testicular diffuse large B-cell lymphomas (PT-DLBCL), the most prevalent subtype of testicular lymphoma, occurs in an immune-privileged site within the testis. Although advances in genomic technologies have resulted in remarkable progress in understanding the pathogenesis of DLBCLs, the characterization of the tumor microenvironment (TME) and spatial organization of PT-DLBCL remains unclear.

This research, published in the Genes & Diseases journal by a team from Zhejiang University, Nantong University, Shanghai Jiao Tong University and Singleron Biotechnologies Ltd., utilized single-cell RNA sequencing (scRNA-seq) and spatial transcriptomics to identify the tissue architecture of PT-DLBCL.

Single-cell RNA-sequencing analysis of normal human testis, paracancerous,
and cancer tissues obtained from a patient with testicular DLBCL

 (A) Schematic of the experimental design and analysis. Paracancerous and cancer tissues obtained from surgically resected DLBCLs were split and processed for scRNA-seq and spatial transcriptomics. (B) Single-cell expression of all cells from healthy, paracancerous, and testicular DLBCL tissues. The red, blue, and orange colors represent cancerous, healthy, and paracancerous cells, respectively. (C) UMAP plot of cells from Figure 1B. Cell types: germ cells, B cells, Sertoli cells, pericytes, Leydig cells, macrophages, T cells, and endothelial cells. (D) Percentages of different cell types in cancerous, paracancerous, and normal cells. (E) Representative gene expression for each cell type. (F) Immunohistochemical staining of primary testicular DLBCL. (+++) represents high expression; (++) represents mild expression; (+) represents low expression; and (−) represents negative expression.

The initial investigation involved profiling of the transcriptomes of 19,559 single cells derived from a PT-DLBCL patient via scRNA-seq. The results revealed that the PT-DLBCL TME was predominantly composed of three exhausted CD8⁺ T cell subpopulations and two B cell subpopulations. Further analysis by the research team revealed significant genetic heterogeneity, providing a deeper understanding of the tumor’s cellular diversity.

Interestingly, the researchers noted that B1 cells constituted 16% of the TME and exhibited a clustered distribution, suggesting a role in tumor progression through distant metastasis. Moreover, inhibition of critical transcription factors, E2F and CREB, reduced cell proliferation, induced apoptosis in human B-lymphoma cells, and inhibited tumor growth in testicular DLBCL xenograft models, underscoring their potential as novel therapeutic targets.

Using chromatin immunoprecipitation sequencing (ChIP-seq), this study identified the enriched loci of E2F and CREB that regulate human B-lymphoma cell proliferation and apoptosis.  Additionally, spatial transcriptomics unveiled the spatial architecture of the TME in DLBCL, where exhausted T cells were strategically positioned around tumor B cells, while macrophages formed an outer ring, encircling the exhausted T cells. Concurrently, the researchers also delineated the expression patterns of key genes such as MALAT1, RPS3A, RPS7, RPS23, RPS27A, IGHM, HINT1, and HSPA8 across various regions.

Despite significant findings, this study has certain limitations, including the use of single patient samples and uneven experimental group sizes. Nonetheless, this study offers insight into the tumorigenic progression mechanisms and potential novel therapeutic opportunities associated with PT-DLBCL.

Source – Compuscript Ltd