Integrated Molecular Analysis Reveals 2 Distinct Subtypes of Pure Seminoma of the Testis

Recent Advancements in Research on DNA Methylation and Testicular Germ Cell Tumors: Unveiling the Intricate Relationship

Testicular germ cell tumors (TGCTs) are the most common type of testicular cancer, with a particularly high incidence in the 15-45-year age category. Although highly treatable, resistance to therapy sometimes occurs, with devastating consequences for the patients. Additionally, the young age at diagnosis and the treatment itself pose a great threat to patients' fertility. Despite extensive research concerning genetic and environmental risk factors, little is known about TGCT etiology. However, epigenetics has recently come into the spotlight as a major factor in TGCT initiation, progression, and even resistance to treatment. As such, recent studies have been focusing on epigenetic mechanisms, which have revealed their potential in the development of novel, non-invasive biomarkers. As the most studied epigenetic mechanism, DNA methylation was the first revelation in this particular field, and it continues to be a main target of investigations as research into its association with TGCT has contributed to a better understanding of this type of cancer and constantly reveals novel aspects that can be exploited through clinical applications. In addition to biomarker development, DNA methylation holds potential for developing novel treatments based on DNA methyltransferase inhibitors (DNMTis) and may even be of interest for fertility management in cancer survivors. This manuscript is structured as a literature review, which comprehensively explores the pivotal role of DNA methylation in the pathogenesis, progression, and treatment resistance of TGCTs.

Deep Learning for Subtypes Identification of Pure Seminoma of the Testis

The most critical step in the clinical diagnosis workflow is the pathological evaluation of each tumor sample. Deep learning is a powerful approach that is widely used to enhance diagnostic accuracy and streamline the diagnosis process. In our previous study using omics data, we identified 2 distinct subtypes of pure seminoma. Seminoma is the most common histological type of testicular germ cell tumors (TGCTs). Here we developed a deep learning decision making tool for the identification of seminoma subtypes using histopathological slides. We used all available slides for pure seminoma samples from The Cancer Genome Atlas (TCGA). The developed model showed an area under the ROC curve of 0.896. Our model not only confirms the presence of 2 distinct subtypes within pure seminoma but also unveils the presence of morphological differences between them that are imperceptible to the human eye.

Understanding Sociodemographic Factors among Hispanics Through a Population-Based Study on Testicular Cancer in Mexico

Testicular cancer (TCa) is a rare malignancy affecting young men worldwide. Sociodemographic factors, especially socioeconomic level (SEL) and healthcare access, seem to impact TCa incidence and outcomes, particularly among Hispanic populations. However, limited research has explored these variables in Hispanic groups. This study aimed to investigate sociodemographic and clinical factors in Mexico and their role in health disparities among Hispanic TCa patients. We retrospectively analyzed 244 Mexican TCa cases between 2007 and 2020 of a representative cohort with diverse social backgrounds from a national reference cancer center. Logistic regression identified risk factors for fatality: non-seminoma histology, advanced stage, and lower education levels. Age showed a significant trend as a risk factor. Patient delay and healthcare distance lacked significant associations. Inadequate treatment response and chemotherapy resistance were more likely in advanced stages, while higher education positively impacted treatment response. Cox regression highlighted non-seminoma histology, below-median SEL, higher education, and advanced-stage survival rates. Survival disparities emerged based on tumor histology and patient SEL. This research underscores the importance of comprehensive approaches that integrate sociodemographic, biological, and environmental factors to address health disparities improving outcomes through personalized interventions in Hispanic individuals with TCa.

Identification of testicular cancer immune infiltrates and novel immune cell subtypes

Testicular germ cell tumors (TGCT) are the most common type of testicular cancer, comprising 90-95% of cases and representing the most prevalent solid malignancy in young adult men. Immune infiltrates play important regulatory roles in tumors, but their role in TGCT remains unclear. Molecular subtyping is a promising way to provide precisely personalized treatment and avoid unnecessary toxicities. This study investigated immune infiltrates, key biomarkers, and immune subtyping of TGCT. In GSE3218, 24 differentially expressed immune genes (immDEGs) were identified. A new risk signature consisting of six immDEGs was developed using these genes. Individuals in the high-risk group had poor overall survival (OS; hazard ratio of 4.61 and P-value < 0.001). We validated the six-immDEGs risk signature in pure seminoma and mixed TGCT types. Two distinct immune patterns (Cluster 1 and Cluster 2) were identified using the consensusclusterplus, and Cluster 1 possessed an unfavorable OS compared with Cluster 2 (hazard ratio, 2.56; P < 0.001). Cluster 1 patients had significantly lower naive B cells, memory B cells, plasma cells, naive CD4 T cells, gamma delta T cells, and activated dendritic cells than Cluster 2 patients. Genes relating to the WNT signaling pathway, TGF-β signaling pathway, antigen processing and presentation, and NK cell-mediated cytotoxicity were associated with TGCT. STC1 was elevated in TGCT tissues, and its high expression showed advanced clinicopathological characteristics and poor prognosis of TGCT. Our findings may contribute to an increased understanding of the onset and progression of TGCT.

Updating germ cell tumour pathogenesis - the ability of seminomas for FOXA2-driven extra-embryonic differentiation

Testicular germ cell tumours are the most common solid malignancies in young men of age 14-44 years. It is generally accepted that both seminomas and non-seminomas arise from a common precursor, the germ cell neoplasia in-situ, which itself is the result of a defective (primordial) germ cell development. The stem cell-like population of the non-seminomas, the embryonal carcinoma, is capable of the differentiation of all three germ layers (teratomas) and extra-embryonic tissues (yolk-sac tumours, choriocarcioma) into cells. In contrast, seminomas are thought to have a limited differentiation potential. Nevertheless, several studies have highlighted their ability to undergo reprogramming to an embryonal carcinoma or differentiation into other non-seminomatous entities. Here, we demonstrate that in approximately 5% of seminomas, the yolk-sac tumour driver gene FOXA2 is detectable at the protein level, indicative of an occult yolk-sac tumour subpopulation that putatively arose from seminoma cells, as the presence of other GCT entities could be excluded. The presence of these subpopulations might render the tumour more aggressive and argue for an adjustment of the therapeutic concept. We used our data to update the model of germ cell tumour pathogenesis, especially regarding the developmental potential of seminomas. Additionally, we suggest to include detection of FOXA2 into standard routine diagnosis of seminomas.

Breaking the Mold: Epigenetics and Genomics Approaches Addressing Novel Treatments and Chemoresponse in TGCT Patients

Testicular germ-cell tumors (TGCT) have been widely recognized for their outstanding survival rates, commonly attributed to their high sensitivity to cisplatin-based therapies. Despite this, a subset of patients develops cisplatin resistance, for whom additional therapeutic options are unsuccessful, and ~20% of them will die from disease progression at an early age. Several efforts have been made trying to find the molecular bases of cisplatin resistance. However, this phenomenon is still not fully understood, which has limited the development of efficient biomarkers and precision medicine approaches as an alternative that could improve the clinical outcomes of these patients. With the aim of providing an integrative landscape, we review the most recent genomic and epigenomic features attributed to chemoresponse in TGCT patients, highlighting how we can seek to combat cisplatin resistance through the same mechanisms by which TGCTs are particularly hypersensitive to therapy. In this regard, we explore ongoing treatment directions for resistant TGCT and novel targets to guide future clinical trials. Through our exploration of recent findings, we conclude that epidrugs are promising treatments that could help to restore cisplatin sensitivity in resistant tumors, shedding light on potential avenues for better prognosis for the benefit of the patients.

Seminoma subtypes differ in the organization and functional state of the immune microenvironment

Seminoma is the most common type of testicular germ cell tumors (TGCTs) among 15-44 years old men. Seminoma treatments include orchiectomy, platinum-based chemotherapy and radiotherapy. These radical treatment methods cause up to 40 severe adverse long-term side effects including secondary cancers. Immunotherapy based on immune checkpoint inhibitors, which showed its efficiency for many types of cancer, can be important alternative to the platinum-based therapy for seminoma patients. However, five independent clinical trials evaluating the efficiency of immune checkpoint inhibitors for TGCTs treatment were shut down at the phase II due to lacking clinical efficacy and detailed mechanisms of this phenomena are yet to be discovered. Recently we identified two distinct seminoma subtypes based on transcriptomic data and here we focused on the analysis of seminoma microenvironment and its subtype-specific characteristics. Our analysis revealed that less differentiated subtype 1 of seminoma has immune microenvironment with significantly lower immune score and larger fraction of neutrophils. Both are features of the immune microenvironment at an early developmental stage. On the contrary, subtype 2 seminoma is characterized by the higher immune score and overexpression of 21 genes related to senescence-associated secretory phenotype. Seminoma single cell transcriptomic data showed that 9 out of 21 genes are predominantly expressed in immune cells. Therefore, we hypothesized that senescence of immune microenvironment can be one of the reasons for seminoma immunotherapy failure.

Supplementary Information

The online version contains supplementary material available at 10.1007/s13205-023-03530-1.

Immune-related mechanisms and immunotherapy in extragonadal germ cell tumors

Purpose of review

Extragonadal germ cell tumors (EGCTs) are relatively rare tumors, accounting for 1%-5% of all GCTs. In this review, we summarize the current research progress regarding the pathogenesis, diagnosis, and treatment of EGCTs from an immunology perspective.

Recent findings

The histological origin of EGCTs is related to a gonadal origin, but they are located outside the gonad. They show great variation in morphology and can occur in the cranium, mediastinum, sacrococcygeal bone, and other areas. The pathogenesis of EGCTs is poorly understood, and their differential diagnosis is extensive and challenging. EGCT behavior varies greatly according to patient age, histological subtype, and clinical stage.

Summary

This review provides ideas for the future application of immunology in the fight against such diseases, which is a hot topic currently.

cfDNA methylation in liquid biopsies as potential testicular seminoma biomarker

Background: Seminoma is a testicular tumor type, routinely diagnosed after orchidectomy. As cfDNA represents a source of minimally invasive seminoma patient management, this study aimed to investigate whether cfDNA methylation of six genes from liquid biopsies, have potential as novel seminoma biomarkers. Materials & methods: cfDNA methylation from liquid biopsies was assessed by pyrosequencing and compared with healthy volunteers' samples. Results: Detailed analysis revealed specific CpGs as possible seminoma biomarkers, but receiver operating characteristic curve analysis showed modest diagnostic performance. In an analysis of panels of statistically significant CpGs, two DNA methylation panels emerged as potential seminoma screening panels, one in blood CpG8/CpG9/CpG10 (KITLG) and the other in seminal plasma CpG1(MAGEC2)/CpG1(OCT3/4). Conclusion: The presented data promote the development of liquid biopsy epigenetic biomarkers in the screening of seminoma patients.