Testicular germ-cell tumours in a broader perspective

Novel Diagnostic Methods and Posttreatment Clinical Phenotypes Among Intracranial Germ Cell Tumors

BACKGROUND

Central nervous system (CNS) germ cell tumors (GCT) are rare and complex pediatric neoplasms, the optimal management of which remains an area of active investigation.

OBJECTIVE

To present an updated cohort study, with particular attention to novel diagnostic methods and posttreatment clinical phenotypes.

METHODS

A single-institution cohort study of 80 primary, neurosurgically managed, CNS GCTs was conducted at Mayo Clinic, 1988-2017.

RESULTS

Postchemotherapy resection (eg, second-look surgery) was frequently required (27.0%), especially after adjuvant therapies for nongerminomatous GCTs (NGGCTs; 14 of 28 cases, excluding mature teratoma) and significantly associated with pineal lesions, as compared to neurohypophyseal or bifocal lesions (43.6% vs 5.9% vs 6.7%, P = .004), a finding that retained statistical significance after adjusting for index extent of resection and histology (P = .04). Essentially every NGGCT case underwent at least 1 craniotomy, either on presentation, as second-look surgery, or following local recurrence. Mature teratomatous tissue was highly incident in second-look specimens (84.2%), even among lesions initially diagnosed as germinomas. Pretreatment cerebrospinal fluid (CSF) cell fraction analysis demonstrated an association between single lesions and neutrophil predominance, whereas nongerminomatous GCTs were associated with increased monocyte fractions.

CONCLUSION

CNS GCTs are clinically heterogeneous lesions, resulting in numerous opportunities for improved understanding and clinical management via novel diagnostic and therapeutic protocols. Samples from second-look surgeries for recurrent germinomas frequently demonstrate teratomatous tissue, suggesting possible underdiagnosis of mixed GCTs-particularly among pineal lesions. GCT subtypes demonstrate differential cell fraction distributions on CSF analysis, a novel and perhaps diagnostically helpful finding that requires validation in external cohorts.

Multimodality treatment for Central Nervous System Germ Cell Tumors: Disease spectrum and management strategies - A tertiary care center experience from India

OBJECTIVE

Intracranial germ cell tumors (GCTs) are relatively rare neoplasms, representing 2-3 % of paediatric brain tumors in Western countries and 8-15 % in East Asia. Here, we discuss the clinical features and treatment outcomes in patients with central nervous system (CNS) GCTs treated at our institute.

METHODS

Medical records of all primary CNS GCT patients were retrieved retrospectively from 2007 to 2019. Demographic, clinical, treatment and follow up details were entered in a predesigned proforma. Overall survival (OS) and progression-free survival was computed using Kaplan-Meier method and Log-Rank test. Effect of various prognostic factors on survival outcomes was assessed by univariate and multivariate analysis.

RESULTS

A total of 28 CNS GCT patients were included in this analysis. Median age at presentation was 17 years (range, 7-45 years) with a male to female ratio of 1.8:1. Pineal region was the commonest location, encountered in 15 patients (53.6 %). Pure germinoma was the most frequent histology observed, seen in 19 patients (67.9 %). Male gender and germinoma histology were highly associated with pineal location (p = 0.043 and p = 0.052, respectively). Fourteen patients underwent surgical intervention and nine patients underwent biopsy for diagnostic purpose or to relieve the obstructive symptoms. Only 23 patients (82.1 %) received chemotherapy. However, all patients received radiotherapy (Craniospinal irradiation/whole brain radiotherapy/whole ventricular radiotherapy/ or local radiotherapy). After a median follow-up of 53 months (range, 7-150), 23 patients (82.1 %) were alive. OS was significantly affected by histology (89 % in germinoma vs. 60 % in non-germinomatous, p = 0.054) and location (93 % in pineal region vs. 64.2 % in other location, p = 0.042). Age, gender and surgery did not have any impact on the survival outcomes.

CONCLUSION

CNS GCTs are relatively rare and heterogeneous neoplasms commonly seen in pineal and suprasellar locations. A combination of chemotherapy and radiotherapy had shown excellent outcomes.

Developing and Using a Data Commons for Understanding the Molecular Characteristics of Germ Cell Tumors

Germ cell tumors (GCTs) are a rare disease, but they account for 15% of all malignancies diagnosed during adolescence. The biological mechanisms underpinning their development are only starting to be explored. Current GCT treatment may be associated with significant toxicity. Therefore, there is an urgent need to understand the molecular basis of GCT and identify biomarkers to tailor the therapy for individual patients. However, this research is severely hamstrung by the rarity of GCTs in individual hospitals/institutes. A publicly available genomic data commons with GCT datasets compiled from different institutes/studies would be a valuable resource to facilitate such research. In this study, we first reviewed publicly available web portals containing GCT genomics data, focusing on comparing data availability, data access, and analysis tools, and the limitations of using these resources for GCT molecular studies. Next, we specifically designed a GCT data commons with a web portal, GCT Explorer, to assist the research community to store, manage, search, share, and analyze data. The goal of this work is to facilitate GCT molecular basis exploration and translational research.

Assessing Homologous Recombination and Interstrand Cross-Link Repair in Embryonal Carcinoma Testicular Germ Cell Tumor Cell Lines

Testicular germ cell tumors (TGCTs) are typically exquisitely sensitive to DNA interstrand cross-link (ICLs) agents. ICLs covalently link both strands of the DNA duplex, impeding fundamental cellular processes like DNA replication to cause cell death. A leading drug used for the treatment of TGCTs is cisplatin, which introduces ICLs and leads to formation of double strand breaks (DSBs), a DNA lesion that can be repaired in the S/G2 phases of the cell cycle by homologous recombination (HR, also termed homology-direct repair). Although most TGCTs respond to cisplatin-induced ICLs, a fraction is resistant to treatment. One proposed mechanism of TGCT resistance to cisplatin is an enhanced ability to repair DSBs by HR. Other than HR, repair of the ICL-lesions requires additional DNA repair mechanisms, whose action might also be implemented in therapy-resistant cells. This chapter describes GFP assays to measure (a) HR proficiency following formation of a DSB by the endonuclease I-SceI, and (b) HR repair induced by site-specific ICL formation involving psoralen. These experimental approaches can be used to determine the proficiency of TGCT cell lines in DSB repair by HR in comparison to HR repair of ICLs, providing tools to better characterize their recombination profile. Protocols of these assays have been adapted for use in Embryonal Carcinoma (EC) TGCT cell lines. Assays only require transient introduction of plasmids within cells, affording the advantage of testing multiple cell lines in a relatively short time.

Cultivation of Testicular Germ Cell Cancer Cell Lines and Establishment of Gene-Edited Subclones Using CRISPR/Cas9

Type II testicular germ cell tumors (GCTs) can be classified as seminoma or embryonal carcinoma. Both subtypes present distinct cellular morphologies and characteristics. Seminomas closely resemble primordial germ cells (PGCs) with respect to their transcriptome and epigenetic signature (DNA hypomethylation). They express the pluripotency markers LIN28, NANOG, and OCT3/4 and the PGC markers SOX17, PRDM1, TFAP2C, DMRT1, and cKIT. Embryonal carcinomas show increased levels of DNA methylation (hypermethylation). They also express the pluripotency markers LIN28, NANOG, and OCT3/4, but additionally DNMT3B and SOX2. In contrast to seminomas, these tumors are pluripotent to totipotent and thus able to differentiate into cells of all three germ layers (teratoma) and extraembryonic tissues (yolk-sac tumor, choriocarcinoma). This protocol summarizes the essential techniques for standard cultivation of seminoma (TCam-2), embryonal carcinoma (NCCIT, NT2/D1, 2102EP), and choriocarcinoma (JEG-3, JAR) cell lines, as well as the methods to establish gene-edited subclones using the CRISPR/Cas9 system.

Metastatic dysgerminoma in a young patient with 46 XY DSD: A rare case report

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A rare case of metastatic dysgerminoma in a young patient with 46XY DSD.

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Incidence of DSD is 1:5000 with 90% of patients having 46XX chromosome and only 10% have 46 XY chromosome.

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Individuals with an underlying DSD, especially with Y chromosome have an increased risk of developing germ cell tumor.

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Dysgerminoma is highly chemosensitive tumor.

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Multidisciplinary approach is required in management of such cases.

The term DSD (Disorders of Sex development) is issued to define those conditions in whom disharmony exists between chromosomal, hormonal and anatomical sex. Parental and patient mental health and quality of life are adversely affected by these conditions. Moreover, individuals with an underlying DSD, especially those with specific Y chromosomal material in their karyotype have an increased risk for developing a germ cell tumor. Here, we present a unique case of 46XY DSD with bilateral dysgerminomas presenting with abdominal mass at the age of 24 years, who was treated with one cycle of chemotherapy comprising of Carboplatin and Etoposide, following which he developed tumor lysis syndrome and later underwent exploratory laparotomy.

Differential gene expression in cisplatin-resistant and -sensitive testicular germ cell tumor cell lines

Testicular germ cell tumors (TGCTs) represent a well curable malignity due to their exceptional response to cisplatin (CDDP). Despite remarkable treatment results, approximately 5% of TGCT patients develop CDDP resistance and die. Exceptional curability makes TGCTs a highly valuable model system for studying the molecular mechanisms of CDDP sensitivity. Our study was aimed at revealing difference in gene expression between the CDDP-resistant and -sensitive TGCT cell lines, and hence at identifying candidate genes that could serve as potential biomarkers of CDDP response. Using gene expression array, we identified 281 genes that are differentially expressed in CDDP-resistant compared to -sensitive TGCT cell lines. The expression of 25 genes with the highest fold change was validated by RT-qPCR. Of them, DNMT3L, GAL, IGFBP2, IGFBP7, L1TD1, NANOG, NTF3, POU5F1, SOX2, WNT6, ZFP42, ID2, PCP4, SLC40A1 and TRIB3, displayed comparable expression change in gene expression array and RT-qPCR, when all CDDP-resistant TGCT cell lines were pairwise combined with all -sensitive ones. Products of the identified genes are pluripotency factors, or are involved in processes, such as cell metabolism, proliferation or migration. We propose that, after clinical validation, these genes could serve as prognostic biomarkers for early detection of CDDP response in TGCT patients.

[What does the oncologist need from the pathologist in testicular cancer?]

BACKGROUND

Testicular type II germ cell tumours (GCTs) are an exemplar of a curable cancer and the most common malignancy in males aged ≤35 years. Even in metastatic stages, about 70% of patients can be cured by cisplatin-based chemotherapy and multimodal treatments. For patients failing platinum-based standard therapy, prognosis is poor and novel biomarkers and therapeutic options are urgently needed.

OBJECTIVES

Discussion of desired histopathological information to guide urologists' and oncologists' decision making in the treatment of male GCTs.

MATERIAL AND METHODS

A narrative review of histopathological key features of male GCT tissue samples for clinical decision making.

RESULTS

Histopathological workup is crucial to identify (i) a GCT origin in cancers of unknown primary based on isochromosome 12p (i(12p)) detection, (ii) the different type II GCT subtypes, and (iii) risk factors, i.e. lymphovascular or rete testis invasion, among others. Proper histopathological diagnosis is indispensable for guideline-endorsed, histology-driven, and risk-adapted treatment decisions, hereby helping to maintain treatment success while reducing the therapeutic burden and potential long-term sequelae of multimodal treatments. For refractory patients failing standard treatment options, prognosis remains poor and, so far, neither predictive or prognostic biomarkers nor novel therapeutic targets have been established.

CONCLUSIONS

Close interaction and interdisciplinary discussion of histopathologic and radiologic findings and established risk factors including serum tumour markers is crucial for successful treatment including intensified strategies, where necessary, or prevention of overtreatment, where possible.

In Search of TGCT Biomarkers: A Comprehensive In Silico and Histopathological Analysis

Testicular germ cell tumors (TGCTs) are ever more affecting the young male population. Germ cell neoplasia in situ (GCNIS) is the origin of TGCTs, namely, seminomas (SE) and a heterogeneous group of nonseminomas (NS) comprising embryonal carcinoma, teratoma, yolk sac tumor, and choriocarcinoma. Response to the treatment and prognosis, especially of NS, depend on precise diagnosis with a necessity for discovery of new biomarkers. We aimed to perform comprehensive in silico analysis at the DNA, RNA, and protein levels of six prospective (HOXA9, MGMT, CFC1, PRSS21, RASSF1A, and MAGEC2) and six known TGCT biomarkers (OCT4, SOX17, SOX2, SALL4, NANOG, and KIT) and assess its congruence with histopathological analysis in all forms of TGCTs. Cancer Hallmarks Analytics Tool, the Search Tool for the Retrieval of Interacting Genes/Proteins database, and UALCAN, an interactive web resource for analyzing cancer OMICS data, were used. In 108 TGCT and 48 tumor-free testicular samples, the immunoreactivity score (IRS) was calculated. SE showed higher frequency in DNA alteration, while DNA methylation was significantly higher for all prospective biomarkers in NS. In GCNIS, we assessed the clinical positivity of RASSF1 and PRSS21 in 52% and 62% of samples, respectively, in contrast to low or nil positivity in healthy seminiferous tubules, TGTCs as a group, SE, NS, or all NS components. Although present in approximately 80% of healthy seminiferous tubules (HT) and GCNIS, HOXA9 was diagnostically positive in 64% of TGCTs, while it was positive in 82% of NS versus 29% of SE. Results at the DNA, mRNA, and protein levels on putative and already known biomarkers were included in the suggested panels that may prove to be important for better diagnostics of various forms of TGCTs.

Establishment and characterisation of testicular cancer patient-derived xenograft models for preclinical evaluation of novel therapeutic strategies

Testicular cancer (TC) is the most common solid tumour in young men. While cisplatin-based chemotherapy is highly effective in TC patients, chemoresistance still accounts for 10% of disease-related deaths. Pre-clinical models that faithfully reflect patient tumours are needed to assist in target discovery and drug development. Tumour pieces from eight TC patients were subcutaneously implanted in NOD scid gamma (NSG) mice. Three patient-derived xenograft (PDX) models of TC, including one chemoresistant model, were established containing yolk sac tumour and teratoma components. PDX models and corresponding patient tumours were characterised by H&E, Ki-67 and cyclophilin A immunohistochemistry, showing retention of histological subtypes over several passages. Whole-exome sequencing, copy number variation analysis and RNA-sequencing was performed on these TP53 wild type PDX tumours to assess the effects of passaging, showing high concordance of molecular features between passages. Cisplatin sensitivity of PDX models corresponded with patients' response to cisplatin-based chemotherapy. MDM2 and mTORC1/2 targeted drugs showed efficacy in the cisplatin sensitive PDX models. In conclusion, we describe three PDX models faithfully reflecting chemosensitivity of TC patients. These models can be used for mechanistic studies and pre-clinical validation of novel therapeutic strategies in testicular cancer.

Serum RNA Profiling in the 10-Years Period Prior to Diagnosis of Testicular Germ Cell Tumor

Although testicular germ cell tumor (TGCT) overall is highly curable, patients may experience late effects after treatment. An increased understanding of the mechanisms behind the development of TGCT may pave the way for better outcome for patients. To elucidate molecular changes prior to TGCT diagnosis we sequenced small RNAs in serum from 69 patients who were later diagnosed with TGCT and 111 matched controls. The deep RNA profiles, with on average 18 million sequences per sample, comprised of nine classes of RNA, including microRNA. We found that circulating RNA signals differed significantly between cases and controls regardless of time to diagnosis. Different levels of TSIX related to X-chromosome inactivation and TEX101 involved in spermatozoa production are among the interesting findings. The RNA signals differed between seminoma and non-seminoma TGCT subtypes, with seminoma cases showing lower levels of RNAs and non-seminoma cases showing higher levels of RNAs, compared with controls. The differentially expressed RNAs were typically associated with cancer related pathways. Our results indicate that circulating RNA profiles change during TGCT development according to histology and may be useful for early detection of this tumor type.

Malignant recurrence after mature Sacrococcygeal teratoma: A meta-analysis and review of the literature

BACKGROUND AND AIMS

Sacrococcygeal teratoma (SCT) is a rare extragonadal germ cell tumour mostly diagnosed during infancy and early childhood. Neonatal SCTs are mostly mature, but can also contain immature and/or malignant components. Recurrence of an SCT alters prognosis, especially when it is malignant, of which its mechanism is not yet fully understood. This study is a review and meta-analysis of the literature on malignant recurrences after an initially mature SCT.

METHODS

A literature search was performed to identify studies describing children with SCT and presenting specific information on histology of the initial tumour as well as the recurrence. Random effect models for mature recurrence and malignant recurrence after an initially mature SCT were employed to pool study-specific percentages in order to estimate an overall percentage and its associated 95 % confidence intervals (CI). Inverse variance method, which gives more weight to larger studies, was used to pool outcomes for the different studies.

RESULTS

A total of 22 articles, comprising 1516 patients with SCT, were included in the meta-analysis. The pooled proportions of mature and malignant recurrences after mature SCT were 3 % (95 % CI 1-4 %) and 5% (95 % CI 3-6 %), respectively. Fifty-seven (56 %) of a total of 102 recurrences after resection of an initially mature SCT were malignant, mostly yolk sac tumour (YST). Many recurrences occurred within 1-6 years, however some occurred as long as 20 years after initial diagnosis.

CONCLUSIONS

A substantial number of recurrences of mature SCT present as a malignant tumour. Overlooking malignant components on initial pathological evaluation and the progression of mature SCT cells to malignant cells may play a role. Treatment of mature SCTs with resection alone requires thorough follow-up of at least 6 years. Future research is needed to determine whether SCTs with malignant microfoci should be treated or followed-up differently from mature or immature SCTs. In addition, the value of serum biomarkers in follow-up after SCT needs to be further evaluated.

Differential expression of DNA methyltransferases and demethylases among the various testicular germ cell tumor subtypes

Aim: Characterize DNA methyltransferases/demethylases expression in testicular germ cell tumors (TGCTs). Methods:In silico analysis of TCGA database, assessment of transcript levels of most relevant enzymes in four TGCT cell lines and validation in patient cohort (real-time quantitative polymerase chain reaction; immunohistochemistry). Results:DNMT3A, DNMT3B and TET2 were the most differentially expressed between seminomas (SEs) and nonseminomas (NSs). DNMT3B was significantly overexpressed in NS-related cell lines, and the opposite was found for TET2. Significantly higher DNMT3A/B mRNA expression was observed in NS, indicating a role for de novo methylation in reprogramming. Significantly higher TET2 protein expression was observed in SEs, suggesting active demethylation contributes for SE hypomethylated state. More differentiated histologies disclosed distinct expression patterns. Conclusion: DNA-modifying enzymes are differentially expressed between TGCT subtypes, influencing reprogramming and differentiation.

Ovarian and non-ovarian teratomas: a wide spectrum of features

Teratoma is a germ cell tumor (GCT) derived from stem cells of the early embryo and the germ line. Teratoma is the most common neoplasm of the ovaries and is usually diagnosed easily using imagings by detecting fat components. However, there are various histopathological types and the imaging findings differ according to the type. Teratoma usually occurs in the gonads or in the midline due to migration of primordial germ cells during development. The clinical course of teratomas depends on the age of the patient, histological type, and anatomical site. Sometimes teratomas show unusual manifestations, such as mature teratoma without demonstrable fat components, torsion, rupture, growing teratoma syndrome, anti-N-methyl-D-aspartate receptor encephalitis, and autoimmune hemolytic anemia. For all of these reasons, teratomas demonstrate a wide spectrum of imaging features and radiologists should be familiar with these variabilities. The present article aims to introduce a model encompassing types of GCTs based on their developmental potential, and to review several histopathological types in various anatomical sites and unusual manifestations of teratomas, with representative imaging findings.

Integrated clinical, histopathological, and molecular data analysis of 190 central nervous system germ cell tumors from the iGCT Consortium

BACKGROUND

We integrated clinical, histopathological, and molecular data of central nervous system germ cell tumors to provide insights into their management.

METHODS

Data from the Intracranial Germ Cell Tumor Genome Analysis (iGCT) Consortium were reviewed. A total of 190 cases were classified as primary germ cell tumors (GCTs) based on central pathological reviews.

RESULTS

All but one of the cases that were bifocal (neurohypophysis and pineal glands) and cases with multiple lesions including neurohypophysis or pineal gland were germinomas (34 of 35). Age was significantly higher in patients with germinoma than other histologies. Comparison between tumor marker and histopathological diagnoses showed that 18.2% of histopathologically diagnosed germinomas were marker positive and 6.1% of non-germinomatous GCTs were marker negative, suggesting a limitation in the utility of markers or histopathology alone using small specimens for diagnosis. Comparison between local and central histopathological diagnoses revealed a discordance of 12.7%. Discordance was significantly less frequent in biopsy cases, implying difficulty in detecting all histopathological components of heterogeneous GCTs. Germinomas at the typical sites (neurohypophysis or pineal gland) showed a better progression-free survival than those at atypical sites (P = 0.03). A molecular clinical association study revealed frequent mitogen-activated protein kinase (MAPK) pathway mutations in males (51.4% vs 14.3%, P = 0.007), and phosphatidylinositol-3 kinase/mammalian target of rapamycin (PI3K/mTOR) pathway mutations in basal ganglia cases (P = 0.004). Basal ganglia cases also had frequent chromosomal losses. Some chromosomal aberrations (2q, 8q gain, 5q, 9p/q, 13q, 15q loss) showed potential prognostic significance.

CONCLUSIONS

The in-depth findings of this study regarding clinical and molecular heterogeneity will increase our understanding of the pathogenesis of this enigmatic tumor.

The decisive role of molecular pathology in presumed somatic metastases of type II testicular germ cell tumors: report of 2 cases

Background

Molecular diagnostics can be decisive in the differential diagnosis between a somatic metastasis of type II testicular germ cell tumor (TGCT) or a second primary carcinoma. This is in line with recent recommendations from the International Society of Urological Pathology, based on an international survey which showed that molecular testing is currently only performed by a minority of urological pathologists.

Case presentations

This case report illustrates the necessity of molecular testing in two patients with a history of type II TGCT and a metastatic (retro) peritoneal carcinoma years later. The genetic hallmark of type II TGCT, chromosome 12p gain, was studied by fluorescence in situ hybridization and whole genome methylation profiling in case 1, and by single nucleotide polymorphism (SNP)-array in case 2. Next generation sequencing (NGS) was used to further explore clonality between the primary TGCT and peritoneal metastasis in case 2. In case 1, chromosome 12p gain was found in the primary type II TGCT and in the acinar cell carcinoma of the metastatic malignancy. In case 2, SNP array showed 12p gain in the epithelial component of the primary teratomatous TGCT but not in the peritoneal adenocarcinoma. Furthermore, NGS showed no mutations in the primary teratomatous TGCT but a KRAS and GNAS mutation in the peritoneal adenocarcinoma, suggestive of an appendicular origin.

Conclusions

Without the molecular data, both cases would have been regarded as a metastatic TGCT with development of somatic-type malignancy, which appeared a wrong diagnosis for case 2. These cases demonstrate the importance of molecular methods as an adjunct in today’s pathology practice.

Report From the International Society of Urological Pathology (ISUP) Consultation Conference on Molecular Pathology of Urogenital Cancers: IV: Current and Future Utilization of Molecular-Genetic Tests for Testicular Germ Cell Tumors

The International Society of Urological Pathology (ISUP) organized a Consultation Conference in March 2019 dealing with applications of molecular pathology in Urogenital Pathology, including testicular tumors (with a focus on germ cell tumors [GCTs]), preceded by a survey among its members to get insight into current practices in testicular germ cell tumor (TGCT) diagnostics and adoption of the ISUP immunohistochemical guidelines published in 2014. On the basis of the premeeting survey, the most commonly used immunomarker panel includes OCT3/4, placental alkaline phosphate, D2-40, SALL4, CD117, and CD30 for GCTs and the documentation of germ cell neoplasia in situ (GCNIS). Molecular testing, specifically 12p copy gain, is informative to distinguish non-GCNIS versus GCNIS related GCTs, and establishing germ cell origin of tumors both in the context of primary and metastatic lesions. Other molecular methodologies currently available but not widely utilized for TGCTs include genome-wide and targeted approaches for specific genetic anomalies, P53 mutations, genomic MDM2 amplification, and detection of the p53 inactivating miR-371a-3p. The latter also holds promise as a serum marker for malignant TGCTs. This manuscript provides an update on the classification of TGCTs, and describes the current and future role of molecular-genetic testing. The following recommendations are made: (1) Presence of GCNIS should be documented in all cases along with extent of spermatogenesis; (2) Immunohistochemical staining is optional in the following scenarios: identification of GCNIS, distinguishing embryonal carcinoma from seminoma, confirming presence of yolk sac tumor and/or choriocarcinoma, and differentiating spermatocytic tumor from potential mimics; (3) Detection of gain of the short arm of chromosome 12 is diagnostic to differentiate between non-GCNIS versus GCNIS related GCTs and supportive to the germ cell origin of both primary and metastatic tumors.

Development of a Data Model and Data Commons for Germ Cell Tumors

Germ cell tumors (GCTs) are considered a rare disease but are the most common solid tumors in adolescents and young adults, accounting for 15% of all malignancies in this age group. The rarity of GCTs in some groups, particularly children, has impeded progress in treatment and biologic understanding. The most effective GCT research will result from the interrogation of data sets from historical and prospective trials across institutions. However, inconsistent use of terminology among groups, different sample-labeling rules, and lack of data standards have hampered researchers' efforts in data sharing and across-study validation. To overcome the low interoperability of data and facilitate future clinical trials, we worked with the Malignant Germ Cell International Consortium (MaGIC) and developed a GCT clinical data model as a uniform standard to curate and harmonize GCT data sets. This data model will also be the standard for prospective data collection in future trials. Using the GCT data model, we developed a GCT data commons with data sets from both MaGIC and public domains as an integrated research platform. The commons supports functions, such as data query, management, sharing, visualization, and analysis of the harmonized data, as well as patient cohort discovery. This GCT data commons will facilitate future collaborative research to advance the biologic understanding and treatment of GCTs. Moreover, the framework of the GCT data model and data commons will provide insights for other rare disease research communities into developing similar collaborative research platforms.

Molecular and epigenetic pathogenesis of germ cell tumors

The development of germ cell tumors (GCTs) is a unique pathogenesis occurring at an early developmental stage during specification, migration or colonization of primordial germ cells (PGCs) in the genital ridge. Since driver mutations could not be identified so far, the involvement of the epigenetic machinery during the pathogenesis seems to play a crucial role. Currently, it is investigated whether epigenetic modifications occurring between the omnipotent two-cell stage and the pluripotent implanting PGCs might result in disturbances eventually leading to GCTs. Although progress in understanding epigenetic mechanisms during PGC development is ongoing, little is known about the complete picture of its involvement during GCT development and eventual classification into clinical subtypes. This review will shed light into the current knowledge of the complex epigenetic and molecular contribution during pathogenesis of GCTs by emphasizing on early developmental stages until arrival of late PGCs in the gonads. We questioned how misguided migrating and/or colonizing PGCs develop to either type I or type II GCTs. Additionally, we asked how pluripotency can be regulated during PGC development and which epigenetic changes contribute to GCT pathogenesis. We propose that SOX2 and SOX17 determine either embryonic stem cell-like (embryonal carcinoma) or PGC-like cell fate (seminoma). Finally, we suggest that factors secreted by the microenvironment, i.e. BMPs and BMP inhibiting molecules, dictate the fate decision of germ cell neoplasia in situ (into seminoma and embryonal carcinoma) and seminomas (into embryonal carcinoma or extraembryonic lineage), indicating an important role of the microenvironment on GCT plasticity.

CDK4/6 inhibition presents as a therapeutic option for paediatric and adult germ cell tumours and induces cell cycle arrest and apoptosis via canonical and non-canonical mechanisms

BACKGROUND

Germ cell tumours (GCTs) are the most common solid malignancies in young men. Although high cure rates can be achieved, metastases, resistance to cisplatin-based therapy and late toxicities still represent a lethal threat, arguing for the need of new therapeutic options. In this study, we analysed the potential of cyclin-dependent kinase 4/6 (CDK4/6) inhibitors palbociclib and ribociclib (PaRi) as molecular drugs to treat cisplatin-resistant and -sensitive paediatric and adult GCTs.

METHODS

Ten GCT cell lines, including cisplatin-resistant subclones and non-malignant controls, were treated with PaRi and screened for changes in viability (triphenyl tetrazolium chloride (XTT) assay), apoptosis rates (flow cytometry, caspase assay), the cell cycle (flow cytometry), the transcriptome (RNA-sequencing, quantitative reverse transcriptase-polymerase chain reaction (qRT-PCR) and on protein level (western blot). Expression profiling was performed on paediatric and adult GCT tissues (expression microarrays, qRT-PCR, immunohistochemistry, 'The Cancer Genome Atlas' database).

RESULTS

We demonstrate that adult GCTs highly express CDK4, while paediatric GCTs strongly express CDK6 instead. Thus, both GCT types are potentially treatable by PaRi. GCTs presented as highly sensitive towards PaRi, which caused a decrease in viability, cell cycle arrest and apoptosis. Although GCTs mainly arrested in the G1/G0 phase, some embryonal carcinoma cell lines were able to bypass the G1/S checkpoint and progressed to the G2/M phase. We found that upregulation of CDK3 and downregulation of many mitosis regulation factors, like the HAUS genes, might be responsible for bypassing the G1/S checkpoint and termination of mitosis, respectively. We postulate that GCT cells do not tolerate these alterations in the cell cycle and eventually induce apoptosis.

CONCLUSION

Our study highlights PaRi as therapeutic options for cisplatin-resistant and -sensitive paediatric and adult GCTs.

Fluorescent In Situ Hybridization Analysis for 12p Alterations in Sarcomatoid Yolk Sac Tumors

"Sarcomas" in patients with testicular germ cell tumors (GCTs) are a common form of "somatic-type malignancy." There is support, based on morphology and immunohistochemistry, that many such sarcomatous tumors represent an unusual form of yolk sac tumor (YST). A virtually universal chromosomal anomaly in GCTs is increase in 12p copy number, often in the form of isochromosome 12p [i(12p)], but this aspect of sarcomatoid YSTs has not hitherto been studied. We performed interphase fluorescent in situ hybridization assay for detection of increased 12p copy number in sarcomatoid YSTs using a bacterial artificial chromosome-derived probe localized to 12p12.1 and a commercially available centromeric probe. Sixteen formalin-fixed, paraffin-embedded specimens from 11 patients, along with normal controls, were studied. Overrepresentation of 12p was expressed as a ratio between the number of signals for 12p and the number of signals for centromere 12. A ratio ≥1.3 was considered overrepresentation. All cases were postchemotherapy recurrences or metastases. Ages ranged 22 to 38 years (mean: 36). Most tumors (12/16) showed myxoid or fibromyxoid stroma and 15 of 16 were high grade. Thirteen of 16 specimens (81%) showed overrepresentation of 12p by the above criteria. Two cases exhibited loss of 12p and 1 case had gain of a whole chromosome 12 (trisomy 12). We conclude that, as in other GCTs, sarcomatous differentiation of YST demonstrates 12p alterations that can be identified by interphase fluorescent in situ hybridization. Apart from 12p overrepresentation, these tumors may exhibit loss of 12p or even gain of an entire chromosome 12 (trisomy 12). Increase in 12p copy number of a sarcomatous neoplasm provides support for sarcomatoid YST in clinically ambiguous settings.

ARID1A Regulates Transcription and the Epigenetic Landscape via POLE and DMAP1 while ARID1A Deficiency or Pharmacological Inhibition Sensitizes Germ Cell Tumor Cells to ATR Inhibition

Germ cell tumors (GCTs) are the most common solid malignancies found in young men. Although they generally have high cure rates, metastases, resistance to cisplatin-based therapy, and late toxicities still represent a lethal threat, arguing for the need of new therapeutic options. In a previous study, we identified downregulation of the chromatin-remodeling SWI/SNF complex member ARID1A as a key event in the mode of action of the histone deacetylase inhibitor romidepsin. Additionally, the loss-of-function mutations re-sensitize different tumor types to various drugs, like EZH2-, PARP-, HDAC-, HSP90- or ATR-inhibitors. Thus, ARID1A presents as a promising target for synthetic lethality and combination therapy. In this study, we deciphered the molecular function of ARID1A and screened for the potential of two pharmacological ARID1A inhibitors as a new therapeutic strategy to treat GCTs. By CRISPR/Cas9, we generated ARID1A-deficient GCT cells and demonstrate by mass spectrometry that ARID1A is putatively involved in regulating transcription, DNA repair and the epigenetic landscape via DNA Polymerase POLE and the DNA methyltransferase 1-associated protein DMAP1. Additionally, ARID1A/ARID1A deficiency or pharmacological inhibition increased the efficacy of romidepsin and considerably sensitized GCT cells, including cisplatin-resistant subclones, towards ATR inhibition. Thus, targeting ARID1A in combination with romidepsin and ATR inhibitors presents as a new putative option to treat GCTs.

Comparing genome-scale DNA methylation and CNV marks between adult human cultured ITGA6+ testicular cells and seminomas to assess in vitro genomic stability

Autologous transplantation of spermatogonial stem cells is a promising new avenue to restore fertility in infertile recipients. Expansion of the initial spermatogonial stem cell pool through cell culturing is a necessary step to obtain enough cells for effective repopulation of the testis after transplantation. Since in vitro propagation can lead to (epi-)genetic mutations and possibly malignant transformation of the starting cell population, we set out to investigate genome-wide DNA methylation status in uncultured and cultured primary testicular ITGA6+ sorted cells and compare them with germ cell tumor samples of the seminoma subtype. Seminomas displayed a severely global hypomethylated profile, including loss of genomic imprinting, which we did not detect in cultured primary testicular ITGA6+ cells. Differential methylation analysis revealed altered regulation of gamete formation and meiotic processes in cultured primary testicular ITGA6+ cells but not in seminomas. The pivotal POU5F1 marker was hypomethylated in seminomas but not in uncultured or cultured primary testicular ITGA6+ cells, which is reflected in the POU5F1 mRNA expression levels. Lastly, seminomas displayed a number of characteristic copy number variations that were not detectable in primary testicular ITGA6+ cells, either before or after culture. Together, the data show a distinct DNA methylation patterns in cultured primary testicular ITGA6+ cells that does not resemble the pattern found in seminomas, but also highlight the need for more sensitive methods to fully exclude the presence of malignant cells after culture and to further study the epigenetic events that take place during in vitro culture.

Application of miRNAs in the diagnosis and monitoring of testicular germ cell tumours

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.

Age-Dependent Presentation and Clinical Course of 1465 Patients Aged 0 to Less than 18 Years with Ovarian or Testicular Germ Cell Tumors; Data of the MAKEI 96 Protocol Revisited in the Light of Prenatal Germ Cell Biology

OBJECTIVE

To evaluate prognostic factors in pediatric patients with gonadal germ cell tumors (GCT).

METHODS

Patients <18 years with ovarian and testicular GCT (respectively OGCT and TGCT) were prospectively registered according to the guidelines of MAKEI 96. After resection of the primary tumor, patients staged ≥II received risk-stratified cisplatin-based combination chemotherapy. Patients were analyzed in respect to age (six age groups divided into 3-year intervals), histology, stage, and therapy. The primary end point was overall survival.

RESULTS

Between January 1996 and March 2016, the following patients were registered: 1047 OGCT, of those, 630 had ovarian teratoma (OTER) and 417 had malignant OGCT (MOGCT); and 418 TGCT, of those, 106 had testicular teratoma (TTER) and 312 had malignant TGCT (MTGCT). Only in MTGCT, older age correlated with a higher proportion of advanced tumors. All 736 teratomas and 240/415 stage I malignant gonadal GCT underwent surgery and close observation alone. In case of watchful waiting, the progression rate of OGCT was higher than that of TGCT. However, death from disease was reported in 8/417 (1.9%) MOGCT and 8/312 (2.6%) MTGCT irrespective of adjuvant chemotherapy and repeated surgery.

CONCLUSIONS

The different pathogenesis and histogenesis of gonadal GCT reflects sex- and age-specific patterns that define clinically relevant risk groups. Therefore, gender and age should be considered in further research on the biology and clinical practice of pediatric gonadal GCT.

Salvage treatment for children with relapsed/refractory germ cell tumors: The Associazione Italiana Ematologia Oncologia Pediatrica (AIEOP) experience

BACKGROUND

Malignant germ cell tumors (GCTs) are a heterogeneous group of rare neoplasms in children. Optimal outcome is achieved with multimodal therapies for patients with both localized and advanced disease, especially after the introduction of platinum-based chemotherapy regimens. In this respect, data on salvage treatment for children with relapsed or platinum-refractory disease are still limited.

METHODS

Retrospective analysis of data regarding patients affected by malignant GCTs with platinum-refractory or relapsed disease after first-line treatment according to AIEOP TCGM 2004 protocol was conducted.

RESULTS

Twenty-one patients, 15 females and 6 males, were considered for the analysis. All 21 patients received second-line conventional chemotherapy (SLCT), two of these immediately after surgery for local relapse removal. Two patients showed a progression of disease during SLCT and died of disease shortly thereafter, whereas 19 patients were in partial remission (PR) or complete remission (CR) after SLCT. Treatment after SLCT consisted in surgery on residual tumor mass (9/19) followed by high dose of chemotherapy (HDCT) with autologous hematopoietic stem cell support (16/19). The overall survival (OS) and event-free survival of the whole populations are 71% and 66.6%, respectively. Platinum-refractory patients OS is 54.5% compared with 91.5% of the relapsed group. There were no treatment-related deaths.

CONCLUSION

SLCT followed or not by HDCT is an effective salvage treatment for children with relapsed/refractory GCTs. However, the role of HDCT following SLCT needs to be further investigated, especially regarding the identification of specific patient subgroups, which can benefit from this more intensive treatment.

Mammalian germ cells are determined after PGC colonization of the nascent gonad

Mammalian primordial germ cells (PGCs) are induced in the embryonic epiblast, before migrating to the nascent gonads. In fish, frogs, and birds, the germline segregates even earlier, through the action of maternally inherited germ plasm. Across vertebrates, migrating PGCs retain a broad developmental potential, regardless of whether they were induced or maternally segregated. In mammals, this potential is indicated by expression of pluripotency factors, and the ability to generate teratomas and pluripotent cell lines. How the germline loses this developmental potential remains unknown. Our genome-wide analyses of embryonic human and mouse germlines reveal a conserved transcriptional program, initiated in PGCs after gonadal colonization, that differentiates germ cells from their germline precursors and from somatic lineages. Through genetic studies in mice and pigs, we demonstrate that one such gonad-induced factor, the RNA-binding protein DAZL, is necessary in vivo to restrict the developmental potential of the germline; DAZL's absence prolongs expression of a Nanog pluripotency reporter, facilitates derivation of pluripotent cell lines, and causes spontaneous gonadal teratomas. Based on these observations in humans, mice, and pigs, we propose that germ cells are determined after gonadal colonization in mammals. We suggest that germ cell determination was induced late in embryogenesis-after organogenesis has begun-in the common ancestor of all vertebrates, as in modern mammals, where this transition is induced by somatic cells of the gonad. We suggest that failure of this process of germ cell determination likely accounts for the origin of human testis cancer.

The oncogene Gankyrin is expressed in testicular cancer and contributes to cisplatin sensitivity in embryonal carcinoma cells

BACKGROUND

Testicular germ cell cancer (TGCC) develops from pre-malignant germ neoplasia in situ (GCNIS) cells. GCNIS originates from fetal gonocytes (POU5F1+/MAGE-A4-), which fail to differentiate to pre-spermatogonia (POU5F1-/MAGE-A4+) and undergo malignant transformation. Gankyrin is an oncogene which has been shown to prevent POU5F1 degradation and specifically interact with MAGE-A4 in hepatocellular carcinoma (HCC) cells. We aimed to investigate the role of Gankyrin in progression from gonocyte to pre-invasive GCNIS and subsequent invasive TGCC.

METHODS

We determined Gankyrin expression in human fetal testicular tissue (gestational weeks 9-20; n = 38), human adult testicular tissue with active spermatogenesis (n = 9), human testicular tissue with germ cell maturation delay (n = 4), testicular tissue from patients with pre-invasive GCNIS (n = 6), and invasive TGCC including seminoma (n = 6) and teratoma (n = 7). Functional analysis was performed in-vitro by siRNA knock-down of Gankyrin in the NTera2 cells (derived from embryonal carcinoma).

RESULTS

Germ cell expression of Gankyrin was restricted to a sub-population of prespermatogonia in human fetal testes. Nuclear Gankyrin was also expressed in GCNIS cells of childhood and adult pre-invasive TGCC patients, and in GCNIS from seminoma and non-seminoma patients. Cytoplasmic expression was observed in seminoma tumour cells and NTera2 cells. Gankyrin knock-down in NTera2 cells resulted in an increase in apoptosis mediated via the TP53 pathway, whilst POU5F1 expression was unaffected. Furthermore, Gankyrin knock-down in NTera2 cells increased cisplatin sensitivity with an increase in cell death (13%, p < 0.05) following Gankyrin knock-down, when compared to cisplatin treatment alone, likely via BAX and FAS. Our results demonstrate that Gankyrin expression changes in germ cells during normal transition from gonocyte to prespermatogonia. In addition, changes in Gankyrin localisation are associated with progression of pre-invasive GCNIS to invasive TGCC. Furthermore, we found that Gankyrin is involved in the regulation of NTera2 cell survival and that a reduction in Gankyrin expression can modulate cisplatin sensitivity.

CONCLUSIONS

These results suggest that manipulation of Gankyrin expression may reduce the cisplatin dose required for the treatment of TGCC, with benefits in reducing dose-dependent side effects of chemotherapy. Further studies are required in order to assess the effects of modulating Gankyrin on GCNIS/TGCC using in vivo models.

Glycan Analysis as Biomarkers for Testicular Cancer

The U.S. Preventive Services Task Force does not recommend routine screening for testicular cancer (TC) in asymptomatic men, essentially because serological testicular cancer (TC) biomarkers are not reliable. The main reason is that two of the most important TC biomarkers, α-fetoprotein (AFP) and human chorionic gonadotropin (hCG), are not produced solely due to TC. Moreover, up to 40% of patients with TC do not have elevated serological biomarkers, which is why serial imaging with CT is the chief means of monitoring progress. On the other hand, exposure to radiation can lead to an increased risk of secondary malignancies. This review provides the first comprehensive account of the applicability of protein glycoprofiling as a promising biomarker for TC with applications in disease diagnostics, monitoring and recurrence evaluation. The review first deals with the description and classification of TC. Secondly, the limitations of current TC biomarkers such as hCG, AFP and lactate dehydrogenase are provided together with an extensive overview of the glycosylation of hCG and AFP related to TC. The final part of the review summarises the potential of glycan changes on either hCG and AFP as TC biomarkers for diagnostics and prognostics purposes, and for disease recurrence evaluation. Finally, an analysis of glycans in serum and tissues as TC biomarkers is also provided.

Therapeutic Challenges for Cisplatin-Resistant Ovarian Germ Cell Tumors

The majority of patients with advanced ovarian germ cell cancer are treated by cisplatin-based chemotherapy. Despite adequate first-line treatment, nearly one third of patients relapse and almost half develop cisplatin-resistant disease, which is often fatal. The treatment of cisplatin-resistant disease is challenging and prognosis remains poor. There are limited data on the efficacy of specific chemotherapeutic regimens, high-dose chemotherapy with autologous progenitor cell support and targeted therapies. The inclusion of patients in clinical trials is strongly recommended, especially in clinical trials on the most frequent male germ cell tumors, to offer wider therapeutic opportunities. Here, we provide an overview of current and potential new treatment options including combination chemotherapy, high-dose chemotherapy and molecular targeted therapies, for patients with cisplatin-resistant ovarian germ cell tumors.

Predicting Gonadal Germ Cell Cancer in People with Disorders of Sex Development; Insights from Developmental Biology

The risk of gonadal germ cell cancer (GGCC) is increased in selective subgroups, amongst others, defined patients with disorders of sex development (DSD). The increased risk is due to the presence of part of the Y chromosome, i.e., GonadoBlastoma on Y chromosome GBY region, as well as anatomical localization and degree of testicularization and maturation of the gonad. The latter specifically relates to the germ cells present being at risk when blocked in an embryonic stage of development. GGCC originates from either germ cell neoplasia in situ (testicular environment) or gonadoblastoma (ovarian-like environment). These precursors are characterized by presence of the markers OCT3/4 (POU5F1), SOX17, NANOG, as well as TSPY, and cKIT and its ligand KITLG. One of the aims is to stratify individuals with an increased risk based on other parameters than histological investigation of a gonadal biopsy. These might include evaluation of defined susceptibility alleles, as identified by Genome Wide Association Studies, and detailed evaluation of the molecular mechanism underlying the DSD in the individual patient, combined with DNA, mRNA, and microRNA profiling of liquid biopsies. This review will discuss the current opportunities as well as limitations of available knowledge in the context of predicting the risk of GGCC in individual patients.

Targeted treatment approaches in refractory germ cell tumors

Germ cell tumors (GCTs) are the most common type of solid tumor amongst patients between 15 and 35 years of age. They are also one of the types of tumor with the highest cure rate, due to their high sensitivity to cisplatin based chemotherapy. Nonetheless, around 15-20% of metastatic patients will not have curative options after a relapse on the first and second line. This proves that new therapeutic options for these refractory GCTs patients need to be developed. This article offers a bibliographic review of all studies using targeted treatment or immunotherapy for refractory GCTs patients.

Mechanisms of cisplatin sensitivity and resistance in testicular germ cell tumors

Testicular germ cell tumors (TGCTs) are a cancer pharmacology success story with a majority of patients cured even in the highly advanced and metastatic setting. Successful treatment of TGCTs is primarily due to the exquisite responsiveness of this solid tumor to cisplatin-based therapy. However, a significant percentage of patients are, or become, refractory to cisplatin and die from progressive disease. Mechanisms for both clinical hypersensitivity and resistance have largely remained a mystery despite the promise of applying lessons to the majority of solid tumors that are not curable in the metastatic setting. Recently, this promise has been heightened by the realization that distinct (and perhaps pharmacologically replicable) epigenetic states, rather than fixed genetic alterations, may play dominant roles in not only TGCT etiology and progression but also their curability with conventional chemotherapies. In this review, it discusses potential mechanisms of TGCT cisplatin sensitivity and resistance to conventional chemotherapeutics.

XIST-Promoter Demethylation as Tissue Biomarker for Testicular Germ Cell Tumors and Spermatogenesis Quality

BACKGROUND

The event of X chromosome inactivation induced by XIST, which is physiologically observed in females, is retained in testicular germ cell tumors (TGCTs), as a result of a supernumerary X chromosome constitution. X chromosome inactivation also occurs in male germline, specifically during spermatogenesis. We aimed to analyze the promoter methylation status of XIST in a series of TGCT tissues, representative cell lines, and testicular parenchyma.

METHODS

Two independent cohorts were included, comprising a total of 413 TGCT samples, four (T)GCT cell lines, and 86 testicular parenchyma samples. The relative amount of methylated and demethylated XIST promoter fragments was assessed by quantitative methylation-specific PCR (qMSP) and more sensitive high-resolution melting (HRM) methylation analyses.

RESULTS

Seminomas showed a lower amount of methylated XIST fragments as compared to non-seminomas or normal testis (p < 0.0001), allowing for a good discrimination among these groups (area under the curve 0.83 and 0.81, respectively). Seminomas showed a significantly higher content of demethylated XIST as compared to non-seminomas. The percentage of demethylated XIST fragment in cell lines reflected their chromosomal constitution (number of extra X chromosomes). A novel and strong positive correlation between the Johnsen's score and XIST demethylation was identified (r = 0.75, p < 0.0001).

CONCLUSIONS

The X chromosome inactivation event and demethylated XIST promoter are promising biomarkers for TGCTs and for assessing spermatogenesis quality.

Human germ cell tumours from a developmental perspective

Human germ cell tumours (GCTs) are derived from stem cells of the early embryo and the germ line. They occur in the gonads (ovaries and testes) and also in extragonadal sites, where migrating primordial germ cells are located during embryogenesis. This group of heterogeneous neoplasms is unique in that their developmental potential is in effect determined by the latent potency state of their cells of origin, which are reprogrammed to omnipotent, totipotent or pluripotent stem cells. Seven GCT types, defined according to their developmental potential, have been identified, each with distinct epidemiological and (epi)genomic features. Heritable predisposition factors affecting the cells of origin and their niches likely explain bilateral, multiple and familial occurrences of the different types of GCTs. Unlike most other tumour types, GCTs are rarely caused by somatic driver mutations, but arise through failure to control the latent developmental potential of their cells of origin, resulting in their reprogramming. Consistent with their non-mutational origin, even the malignant tumours of the group are characterized by wild-type TP53 and high sensitivity for DNA damage. However, tumour progression and the rare occurrence of treatment resistance are driven by embryonic epigenetic state, specific (sub)chromosomal imbalances and somatic mutations. Thus, recent progress in understanding GCT biology supports a comprehensive developmental pathogenetic model for the origin of all GCTs, and provides new biomarkers, as well as potential targets for treatment of resistant disease.

Ectopic activation of WNT signaling in human embryonal carcinoma cells and its effects in short- and long-term in vitro culture

Human embryonal carcinoma (EC) cells comprise the pluripotent stem cells of malignant non-seminomatous germ cell tumors (GCTs) and represent the malignant counterpart of embryonic stem cells (ESCs). WNT/β-catenin signaling has been implicated in regulating adult and embryonic stem cells although its role in EC cells is less investigated. Here, we studied WNT signaling in a panel of representative pluripotent and nullipotent human EC cell lines. We found that EC cell lines show distinct levels of intrinsic WNT signaling and respond differently to ectopic WNT activation. Short-term activation of WNT signaling induced a differentiation-response in the pluripotent EC cells (NT2 and NCCIT) whereas the nullipotent EC cells (TERA1 and 2102Ep) were refractory and maintained high levels of OCT4 and SSEA4 expression. Long-term activation of WNT signaling in NCCIT and, to a lesser extent, TERA1 cells led to (re)gain of OCT4 expression and a switch from SSEA4 to SSEA1 surface antigens ultimately resulting in OCT4⁺/SSEA4⁻/SSEA1⁺ profile. Cisplatin treatment indicated that the OCT4⁺/SSEA4⁻/SSEA1⁺ NCCIT cells became more resistant to chemotherapy treatment. Our findings are of particular interest for the GCT and ES cell biology and shed light on the role of WNT signaling in human EC cells.

Testis Development

Production of sperm and androgens is the main function of the testis. This depends on normal development of both testicular somatic cells and germ cells. A genetic program initiated from the Y chromosome gene sex-determining region Y (SRY) directs somatic cell specification to Sertoli cells that orchestrate further development. They first guide fetal germ cell differentiation toward spermatogenic destiny and then take care of the full service to spermatogenic cells during spermatogenesis. The number of Sertoli cells sets the limits of sperm production. Leydig cells secrete androgens that determine masculine development. Testis development does not depend on germ cells; that is, testicular somatic cells also develop in the absence of germ cells, and the testis can produce testosterone normally to induce full masculinization in these men. In contrast, spermatogenic cell development is totally dependent on somatic cells. We herein review germ cell differentiation from primordial germ cells to spermatogonia and development of the supporting somatic cells. Testicular descent to scrota is necessary for normal spermatogenesis, and cryptorchidism is the most common male birth defect. This is a mild form of a disorder of sex differentiation. Multiple genetic reasons for more severe forms of disorders of sex differentiation have been revealed during the last decades, and these are described along with the description of molecular regulation of testis development.

Chromosomal gains of 12p and 1q are not associated with inferior outcome of pediatric and adolescent germ cell tumors

BACKGROUND

Pediatric germ cell tumors (GCT) are rare and very heterogeneous neoplasms that show a high diversity in tumor biology and histology. The clinical behavior cannot be predicted based on morphology or immunohistochemistry. The aim of this study was to investigate a large number of pediatric GCT regarding chromosomal gains of 12p and 1q.

METHODS

One hundred and eighty pediatric nonseminomatous GCT, that is, mature teratomas, immature teratomas, yolk sac tumors, and mixed germ cell tumors, from three age groups were evaluated for 1q and 12p gains by fluorescence in situ hybridization in tissue micro arrays. The results were correlated with tumor biology and clinical data.

RESULTS

Eleven out of 143 GCT showed gains of 1q. In 29/157 GCT a gain of 12p was found. Prepubertal patients (≤6 years of age) more often displayed gains of 1q compared to pubertal/adolescent patients (11-17 years of age), whereas pubertal/adolescent patients showed gains of 12p most frequently. Twenty-one out of 155 patients suffered from relapse or metachronous disease. Patients with and without gains of 1q or 12p did not differ in frequency of these events. However, the likelihood of occurrence of these clinical events varied depending on the histological type of the tumor.

CONCLUSION

The biological behavior of pediatric GCT depends more on the histological type of the tumor than on the genetic aberrations examined in this study. Gains of 1q and 12p are not suitable to predict the clinical outcome of GCT in childhood. Nevertheless, both genetic alterations might be used as biomarkers to distinguish different histological types of GCT and therefore could be of diagnostic value, especially in borderline cases.

Male fertility preservation in DSD, XXY, pre-gonadotoxic treatments - Update, methods, ethical issues, current outcomes, future directions

This paper aims at reviewing the fertility preservation strategies that could be considered in several conditions at risk of spermatogonial depletion such as 46,XY disorders of sexual development, Klinefelter syndrome and after gonadotoxic treatment in males highlighting current knowledge on diseases and processes involved in infertility as well as future directions along with their specific ethical issues. While sperm cryopreservation after puberty is the only validated technique for fertility preservation, for prepubertal boys facing gonadotoxic therapies or at risk of testicular tissue degeneration where testicular sperm is not present, cryopreservation of spermatogonial cells may be an option to ensure future parenthood. Promising results with transplantation and in vitro maturation of spermatogonial cells were achieved in animals but so far none of the techniques was applied in humans.

TCam-2 Cells Deficient for SOX2 and FOXA2 Are Blocked in Differentiation and Maintain a Seminoma-Like Cell Fate In Vivo

Testicular germ cell tumors (GCTs) are very common in young men and can be stratified into seminomas and non-seminomas. While seminomas share a similar gene expression and epigenetic profile with primordial germ cells, the stem cell population of the non-seminomas, the embryonal carcinoma (EC), resembles malignant embryonic stem cells. Thus, ECs are able to differentiate into cells of all three germ layers (teratomas) and even extra-embryonic-tissue-like cells (yolk-sac tumor, choriocarcinoma). In the last years, we demonstrated that the cellular microenvironment considerably influences the plasticity of seminomas (TCam-2 cells). Upon a microenvironment-triggered inhibition of the BMP signaling pathway in vivo (murine flank or brain), seminomatous TCam-2 cells reprogram to an EC-like cell fate. We identified SOX2 as a key factor activated upon BMP inhibition mediating the reprogramming process by regulating pluripotency, reprogramming and epigenetic factors. Indeed, CRISPR/Cas9 SOX2-deleted TCam-2 cells were able to maintain a seminoma-cell fate in vivo for about six weeks, but after six weeks in vivo still small sub-populations initiated differentiation. Closer analyses of these differentiated clusters suggested that the pioneer factor FOXA2 might be the driving force behind this induction of differentiation, since many FOXA2 interacting genes and differentiation factors like AFP, EOMES, CDX1, ALB, HAND1, DKK, DLK1, MSX1 and PITX2 were upregulated. In this study, we generated TCam-2 cells double-deficient for SOX2 and FOXA2 using the CRISPR/Cas9 technique and xenografted those cells into the flank of nude mice. Upon loss of SOX2 and FOXA2, TCam-2 maintained a seminoma cell fate for at least twelve weeks, demonstrating that both factors are key players in the reprogramming to an EC-like cell fate. Therefore, our study adds an important piece to the puzzle of GCT development and plasticity, providing interesting insights in what can be expected in a patient, when GCT cells are confronted with different microenvironments.

Meiotic gene activation in somatic and germ cell tumours

Background

Germ cell tumours are uniquely associated with the gametogenic tissues of males and females. A feature of these cancers is that they can express genes that are normally tightly restricted to meiotic cells. This aberrant gene expression has been used as an indicator that these cancer cells are attempting a programmed germ line event, meiotic entry. However, work in non‐germ cell cancers has also indicated that meiotic genes can become aberrantly activated in a wide range of cancer types and indeed provide functions that serve as oncogenic drivers. Here, we review the activation of meiotic factors in cancers and explore commonalities between meiotic gene activation in germ cell and non‐germ cell cancers.

Objectives

The objectives of this review are to highlight key questions relating to meiotic gene activation in germ cell tumours and to offer possible interpretations as to the biological relevance in this unique cancer type.

Materials and Methods

PubMed and the GEPIA database were searched for papers in English and for cancer gene expression data, respectively.

Results

We provide a brief overview of meiotic progression, with a focus on the unique mechanisms of reductional chromosome segregation in meiosis I. We then offer detailed insight into the role of meiotic chromosome regulators in non‐germ cell cancers and extend this to provide an overview of how this might relate to germ cell tumours.

Conclusions

We propose that meiotic gene activation in germ cell tumours might not indicate an unscheduled attempt to enter a full meiotic programme. Rather, it might simply reflect either aberrant activation of a subset of meiotic genes, with little or no biological relevance, or aberrant activation of a subset of meiotic genes as positive tumour evolutionary/oncogenic drivers. These postulates provide the provocation for further studies in this emerging field.

Identification of testicular cancer driver genes by a cross-species comparative oncology approach

BACKGROUND

Germ cell tumors arise in the testis, ovary, or extragonadal locations and have a wide range of histopathological and clinical presentations. The relative lack of animal models of germ cell tumors has impeded functional assessment of candidate driver genes. Previously, we described the development of testicular germ cell tumors in zebrafish carrying a mutation in bmpr1bb, a BMP family receptor, and demonstrated that human germ cell tumors have defects in BMP signaling.

OBJECTIVE

To further credential the zebrafish model for studies of human germ cell tumor, and to elucidate conserved genetic programs underlying the development of germ cell tumor.

MATERIALS AND METHODS

We used genetic techniques to ablate the germ cell lineage in developing fish and tested tumors for loss-of-heterozygosity of the wild-type allele of bmpr1bb. We performed comparative gene expression profiling of zebrafish and human germ cell tumors and carried out functional studies of selected genes.

RESULTS

Ablation of germ cells completely prevents testis tumor formation in the fish, definitively establishing the germ cell origin of the tumors. Germ cell tumors in bmpr1bb heterozygous mutants retain the wild-type allele, indicating haploinsufficiency of bmpr1bb as the mechanism of tumor formation. Comparison of RNA-Seq and microarray data from human and zebrafish germ cell tumors revealed a unique overlapping signature shared by the zebrafish tumors with human seminomas, yolk sac tumors, and embryonal carcinomas. The most highly conserved gene set in this cross-species analysis included potential driver genes such as JUP, which we show to be essential for germ cell tumor cell growth.

CONCLUSION

Our findings highlight the value of cross-species comparative oncology for the identification of candidate human cancer genes.

An up-date on novel molecular targets in testicular germ cell tumors subtypes

Testicular germ cell tumors (TGCTs) are the most frequent solid malignant tumors in men 20-34 years of age and the most frequent cause of death from solid tumors in this age group. In addition, the incidence of these tumors has significantly increased over the last few decades. Testicular germ cell tumors are classified into seminoma and nonseminoma germ cell tumors (NSGCTs). NSGCTs can be further divided into embryonal carcinoma, Teratoma, yolk sac tumor, and choriocarcinoma. There are noteworthy differences about therapy and prognosis of seminomas and nonseminoma germ cell tumors, even though both share characteristics of the primordial germ cells (PGCs). Many discovered biomarkers including HMGA1, GPR30, Aurora-B, estrogen receptor β, and others have given further advantage to discriminate between histological subgroups and could represent useful molecular therapeutic targets.