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Seminoma is the most common malignant solid tumor in 14 to 44 year-old men. However, its molecular features and tumor microenvironment (TME) is largely unexplored. Here, we perform a series of studies via genomics profiling (single cell multi-omics and spatial transcriptomics) and functional examination using seminoma samples and a seminoma cell line. We identify key gene expression programs share between seminoma and primordial germ cells, and further characterize the functions of TFAP2C in promoting tumor invasion and migration. We also identify 15 immune cell subtypes in TME, and find that subtypes with exhaustion features were located closer to the tumor region through combined spatial transcriptome analysis. Furthermore, we identify key pathways and genes that may facilitate seminoma disseminating beyond the seminiferous tubules. These findings advance our knowledge of seminoma tumorigenesis and produce a multi-omics atlas of in situ human seminoma microenvironment, which could help discover potential therapy targets for seminoma. The molecular features and tumour microenvironment (TME) in seminoma remain to be characterised. Here, the authors perform single cell multi-omics and spatial transcriptomics and identify key gene expression programmes, immune cell subtypes and potential therapeutic targets.

Germ cell tumors (GCTs) pose significant diagnostic challenges because of the limited performance of existing tumor markers. Here, we used phage immunoprecipitation sequencing (PhIP-Seq) to develop a unique immunosignature panel to improve diagnosing and differentiating GCT. Using 427 serum samples (150 GCT, 277 controls), we developed and validated an immunosignature panel (GCT-iSIGN) comprising 24 peptides from 16 unique proteins. This panel achieved 93% sensitivity, 99% specificity, and an area under the curve (AUC) of 0.98, identifying 23/24 biomarker-negative GCT cases. A secondary model (Sem-iSIGN), consisting of 17 peptides from five proteins, differentiated seminoma from nonseminoma with 96% specificity, 65% sensitivity, and AUC of 0.77. RNA sequencing data from The Cancer Genome Atlas confirmed differential overexpression of target antigens in testicular cancer. ELISA validation of ERVK7 and LUZP4 and immunohistochemical detection of ERVK7, MUC4, ZNF91, and LUZP4 in tumor tissues supported target expression. This study highlights PhIP-Seq immunoprofiling to identify serum-based immunosignature panels that can serve as biomarkers for GCTs. This approach addresses the shortcomings of conventional markers and offers a scalable, cost-effective tool for improving cancer diagnosis and management. Germ cell tumours are a complex and heterogenous type of tumour which are difficult to classify using biomarkers. Here, the authors use PhIP-seq to develop an immunosignature panel for classification.

Testicular germ cell tumours (TGCTs) are the most frequent cancer type in young men and originate from the common precursor germ cell neoplasia in situ (GCNIS). For decades, clinical management of patients with TGCT has relied on classic serum tumour markers: α-fetoprotein, human chorionic gonadotropin subunit-β and lactate dehydrogenase. In the past 10 years, microRNAs have been shown to outperform classic serum tumour markers in the diagnosis of primary tumours and in follow-up monitoring and prediction of relapse. miR-371a-3p is the most consistent marker and exhibits >90% diagnostic sensitivity and specificity in TGCT. However, miR-371a-3p cannot be used to diagnose GCNIS or mature teratoma. Future efforts must technically standardize the microRNA-based methods internationally and introduce miR-371a-3p as a molecular liquid biopsy-based marker for TGCTs in the clinic.Here, the authors discuss embryonic microRNAs that are highly expressed in testicular germ cell tumours, critically assess the clinical utility of monitoring these microRNAs in the circulation and compare their diagnostic performance with the classic serum tumour markers.

Recent studies have revealed that feed-forward loops (FFLs) as regulatory motifs have synergistic roles in cellular systems and their disruption may cause diseases including cancer. FFLs may include two regulators such as transcription factors (TFs) and microRNAs (miRNAs). In this study, we extensively investigated TF and miRNA regulation pairs, their FFLs, and TF-miRNA mediated regulatory networks in two major types of testicular germ cell tumors (TGCT): seminoma (SE) and non-seminoma (NSE). Specifically, we identified differentially expressed mRNA genes and miRNAs in 103 tumors using the transcriptomic data from The Cancer Genome Atlas. Next, we determined significantly correlated TF-gene/miRNA and miRNA-gene/TF pairs with regulation direction. Subsequently, we determined 288 and 664 dysregulated TF-miRNA-gene FFLs in SE and NSE, respectively. By constructing dysregulated FFL networks, we found that many hub nodes (12 out of 30 for SE and 8 out of 32 for NSE) in the top ranked FFLs could predict subtype-classification (Random Forest classifier, average accuracy ≥90%). These hub molecules were validated by an independent dataset. Our network analysis pinpointed several SE-specific dysregulated miRNAs (miR-200c-3p, miR-25-3p, and miR-302a-3p) and genes ( EPHA2, JUN, KLF4, PLXDC2, RND3, SPI1 , and TIMP3 ) and NSE-specific dysregulated miRNAs (miR-367-3p, miR-519d-3p, and miR-96-5p) and genes ( NR2F1 and NR2F2 ). This study is the first systematic investigation of TF and miRNA regulation and their co-regulation in two major TGCT subtypes.

Testicular germ cell tumours (TGCT), which comprise seminoma and non-seminoma subtypes, are the most common cancers in young men. In this study, we present a comprehensive whole genome sequencing analysis of adult TGCTs. Leveraging samples from participants recruited via the UK National Health Service and data from the Genomics England 100,000 Genomes Project, our results provide an extended description of genomic elements underlying TGCT pathogenesis. This catalogue offers a comprehensive, high-resolution map of copy number alterations, structural variation, and key global genome features, including mutational signatures and analysis of extrachromosomal DNA amplification. This study establishes correlations between genomic alterations and histological diversification, revealing divergent evolutionary trajectories among TGCT subtypes. By reconstructing the chronological order of driver events, we identify a subgroup of adult TGCTs undergoing relatively late whole genome duplication. Additionally, we present evidence that human leukocyte antigen loss is a more prevalent mechanism of immune disruption in seminomas. Collectively, our findings provide valuable insights into the developmental and immune modulatory processes implicated in TGCT pathogenesis and progression. Testicular germ cell tumours (TGCT) are the most common cancers in young men. Here, the authors analyse the genomic landscape of TGCT using data from the Genomics England 100,000 Genomes Project, revealing divergent evolutionary trajectories and the prevalence of human leukocyte antigen loss.

Testicular cell differentiation is a highly regulated process, essential for male reproductive health. The histone variant H3.5 is apparently a critical player in this intricate orchestra of cell types, but its regulation and function remains poorly understood. To elucidate its role, we fractionized testicular cells using c-Kit/CD117 as a separation marker and analyzed H3.5 expression. Further, we investigated the regulation of H3.5 expression using public data repositories. We explored DNA methylation patterns in specific regions of the H3-5 gene and assessed H3-5 copy number gain in seminoma specimens. Additionally, we examined the testicular localization of H3.5 and its histone chaperone interactions to understand its regulation at the protein level. We used qRT-PCR, MeDIP, and qPCR to study H3.5 expression and DNA methylation in various cell types. H3-5 copy number gain was analyzed using qPCR. Protein interactions were investigated through fluorescence-2-hybrid assays in baby hamster kidney cells. H3.5 is primarily enriched in spermatocytes. DNA methylation of a CpG island overlapping the H3-5 promoter appeared to be involved in the tissue-specific regulation of H3.5 expression. Elevated H3.5 expression was observed in seminoma specimens, suggesting a potential link to testicular tumors. H3-5 copy number gain was associated with elevated H3.5 expression in seminoma specimens. Furthermore, we identified physical interactions between H3.5 and histone chaperones Asf1a and Asf1b, HIRA, CAF p150 and DAXX, shedding light on the protein-level regulation of H3.5. These findings provide valuable insights into the molecular mechanisms governing testicular cell differentiation and the potential role of H3.5 in testicular pathologies.

This study aims to investigate the molecular mechanisms underlying germ cell tumors (GCTs), focusing specifically on seminomas and teratomas. By analyzing gene expression profiles and miRNA interactions, the goal is to identify key regulatory miRNAs and signaling pathways that differentiate these tumor types and could serve as important regulators for therapy development. Raw data for seminomas and teratomas were extracted from the GEO database, and gene hubs were identified using STRING and Gephi. Signaling pathways and functional annotations were analyzed using miRPathDB, while miRNA–gene interactions were explored via miRWalk. Hub miRNAs were filtered and confirmed using miRDB. This study highlights significant changes in gene expression diversity between tumor and normal gonadal tissues, providing insights into the molecular dynamics of seminomas and teratomas. Distinctions between seminomas and teratomas were identified, shifting the focus toward miRNAs to discover more precise and novel therapeutic approaches. The hub genes of seminomas and teratomas were identified separately. MiRNAs targeting these hub genes were also determined and confirmed. These miRNAs collectively influence essential oncogenic pathways—confirming hsa-miR-138-5p as a regulator of pathways such as Hippo signaling, transcriptional misregulation in cancer, and microRNA cancer signaling in seminomas, and hsa-miR-200b-3p as a regulator of p53 signaling, T cell receptor signaling, and pathways including PI3K/AKT, MAPK/ERK, and Wnt/β-catenin in teratomas—confirming their potential as promising candidates for subtype-specific therapeutic intervention. MiRNAs identified through bioinformatics analyses, and their predicted regulatory roles in key oncogenic pathways, represent potential therapeutic targets or regulators of biological processes. However, further experimental validation is needed to confirm these findings.

MicroRNA (miRNA) dysregulation is implicated in testicular germ cell tumor (TGCT) pathogenesis. Here, we characterized miRNA expression profiles across TGCT histologic subtypes using miRNA-sequencing on 43 formalin-fixed paraffin-embedded (FFPE) tissue samples (31 primary, 12 metastases) from 29 patients to identify diagnostic markers and their regulatory functions. From 20 seminomas (SEM), 14 non-seminomatous germ cell tumors (N-SEM), and 9 teratomas, we profiled a total of 2606 miRNAs. Compared to teratomas, 154 miRNAs (targeting 657 genes) were enriched in SEM, and 141 miRNAs (targeting 358 genes) in N-SEM. miR-200-3p, targeting the DNA methyltransferase DNMT3B, was enriched in N-SEM versus SEM. Our findings showed high concordance with The Cancer Genome Atlas (TCGA)-TGCT data (Pearson R > 0.66, p  < 1e−10). miRNA expression was largely similar between primary and metastatic tissues and between chemotherapy-treated and untreated teratomas, reflecting teratoma chemo-resistance. Using novel candidates, miRNA-based logistic regression classifiers distinguished viable GCT (SEM/N-SEM) from teratoma (Area Under the Curve [AUC] > 0.96) and SEM from N-SEM (AUC = 0.81), outperforming well-known miRNA markers. Target gene analysis implicated FOXO and RUNX1 regulation, somatotroph signaling, and height-related pathways. Overall, our comprehensive tissue-level miRNA profiling in TGCTs identified potential diagnostic biomarkers for histologic subtypes, offering insights into miRNA-mediated transcriptional dysregulation.

BackgroundTesticular germ cell tumours (TGCTs) have a high metastasis rate. However, the mechanisms related to their invasion, progression and metastasis are unclear. Therefore, we investigated gene expression changes that might be linked to metastasis in seminomatous testicular germ cell tumour (STGCT) patients.MethodsDefined areas [invasive tumour front (TF) and tumour centre (TC)] of non-metastatic (with surveillance and recurrence-free follow-up >2 years) and metastatic STGCTs were collected separately using laser capture microdissection. The expression of 760 genes related to tumour progression and metastasis was analysed using nCounter technology and validated with quantitative real-time PCR and enzyme-linked immunosorbent assay.ResultsDistinct gene expression patterns were observed in metastatic and non-metastatic seminomas with respect to both the TF and TC. Comprehensive pathway analysis showed enrichment of genes related to tumour functions such as inflammation, angiogenesis and metabolism at the TF compared to the TC. Remarkably, prominent inflammatory and cancer-related pathways, such as interleukin-6 (IL-6) signalling, integrin signalling and nuclear factor-κB signalling, were significantly upregulated in the TF of metastatic vs non-metastatic tumours.ConclusionsIL-6 signalling was the most significantly upregulated pathway in metastatic vs non-metastatic tumours and therefore could constitute a therapeutic target for future personalised therapy. In addition, this is the first study showing intra- and inter-tumour heterogeneity in STGCT.

Background: Recent studies have underlined HMGA protein’s key role in the onset of testicular germ cell tumors, where HMGA1 is differently expressed with respect to the state of differentiation, suggesting its fine regulation as master regulator in testicular tumorigenesis. Several studies have highlighted that the HMGA1 transcript is strictly regulated by a set of inhibitory microRNAs. Thus, the aim of this study is to test whether HMGA1 overexpression in human seminomas may be induced by the deregulation of miR-26a and Let-7a—two HMGA1-targeting microRNAs. Methods: HMGA1 mRNA and Let-7a and miR-26a levels were measured in a seminoma dataset available in the Cancer Genome Atlas database and confirmed in a subset of seminomas by qRT-PCR and western blot. A TCam-2 seminoma cell line was then transfected with Let-7a and miR-26a and tested for proliferation and motility abilities. Results: an inverse correlation was found between the expression of miR-26a and Let-7a and HMGA1 expression levels in seminomas samples, suggesting a critical role of these microRNAs in HMGA1 levels regulation. Accordingly, functional studies showed that miR-26a and Let-7a inhibited the proliferation, migration and invasion capabilities of the human seminoma derived cell line TCam-2. Conclusions: these data strongly support that the upregulation of HMGA1 levels occurring in seminoma is—at least in part—due to the downregulation of HMGA1-targeting microRNAs.