Immunoreactive neuron-specific enolase (NSE) is expressed in testicular carcinoma-in-situ

Human spermatogonial markers

In this review, we provide an up-to-date compilation of published human spermatogonial markers, with focus on the three nuclear subtypes A_dark, A_pale and B. In addition, we have extended our recently published list of putative spermatogonial markers with protein expression and RNA-sequencing data from the Human Protein Atlas and supported these by literature evidence. Most importantly, we have put substantial effort in acquiring a comprehensive list of new and potentially interesting markers by refiltering the raw data of 15 published germ cell expression datasets (four human, eleven rodent) and subsequent building of intersections to acquire a robust, cross-species set of spermatogonia-enriched or -specific transcripts.

Histologic and Immunohistochemical Characterization of a Testicular Mixed Germ Cell Sex Cord-Stromal Tumor and a Leydig Cell Tumor in a Dog

Mixed germ cell sex cord-stromal tumors (MGSCTs) of the testis are rare in dogs. We describe the histopathology and immunohistochemical characteristics of an MGSCT associated with a Leydig cell tumor in a cryptorchid testis. Histologically, MGSCT consisted of two nodules of seminiferous tubules lined by germ cells and Sertoli cells in variable proportions. Germ cells had variable size and nuclear features, with frequent giant cells. Germ cells were evenly mixed with Sertoli cells or located in the center of tubules. Markers that labeled mainly germ cells and few or no Sertoli or Leydig cells were calretinin, KIT, and PGP 9.5. E-cadherin, GATA-4, inhibin-α (INH-α), and neuron-specific enolase (NSE) were predominantly detected in Sertoli cells, whereas melan A was particularly expressed in Leydig cells and vimentin in all three cell types. OCT3/4 was not detected in any cell type. Although more cases of canine MGSCT need to be examined, our results suggest that an immunohistochemical panel of E-cadherin, GATA-4, INH-α, KIT, NSE, PGP 9.5, and melan A will help distinguish the three main cell types in canine testicular germ cell and sex cord-stromal tumors.

Malignant seminoma in two unilaterally cryptorchid stallions

Two unilateral cryptorchid stallions were referred to the clinic because of chronic debilitating condition with emaciation. Rectal examination, and ultrasound and gross examination revealed in both animals an abdominal mass, caudally of the kidney, and multiple nodules spread over the abdomen. Histologic analysis revealed an intra-abdominal malignant seminoma with intraperitoneal and renal metastasis. Interestingly, a seminoma was also present in the descended testis of the draught horse.

Intratubular spermatocytic seminomas in 2 sprague-dawley rats

This report describes 2 cases of spontaneous intratubular spermatocytic seminomas in Sprague-Dawley rats. These rats were sacrificed at 10 weeks old (case 1) and 40 weeks old (case 2), respectively. Macroscopically, there were no remarkable changes in either case. Microscopically, tumor cells were observed within a single seminiferous tubule (case 1) or several seminiferous tubules (case 2). The proliferating tumor cells were a tripartite cell population comprising small lymphocyte-like, intermediate-sized or large-sized cells, with frequent mitoses, arranged in sheets or forming a basal layer around a tubule or tubules. Immunohistochemically, the tumor cells were strongly positive for proliferating cell nuclear antigen and weakly positive for c-kit, neuron specific enolase and VASA. Our cases provide valuable background control information for the occurrence of seminoma in rats.

Human spermatogonial stem cells: a possible origin for spermatocytic seminoma

In mammals, spermatogenesis is maintained throughout life by a small subpopulation of type A spermatogonia called spermatogonial stem cells (SSCs). In rodents, SSCs, or Asingle spermatogonia, form the self-renewing population. SSCs can also divide into Apaired (Apr) spermatogonia that are predestined to differentiate. Apaired spermatogonia produce chains of Aaligned (Aal) spermatogonia that divide to form A1 to A4, then type B spermatogonia. Type B spermatogonia will divide into primary spermatocytes that undergo meiosis. In human, there are only two different types of A spermatogonia, the Adark and Apale spermatogonia. The Adark spermatogonia are considered reserve stem cells, whereas the Apale spermatogonia are the self-renewing stem cells. There is only one generation of type B spermatogonia before differentiation into spermatocytes, which makes human spermatogenesis less efficient than in rodents. Although the biology of human SSCs is not well known, a panel of phenotypic markers has recently emerged that is remarkably similar to the list of markers expressed in mice. One such marker, the orphan receptor GPR125, is a plasma membrane protein that can be used to isolate human SSCs. Human SSCs proliferate in culture in response to growth factors such as GDNF, which is essential for SSC self-renewal in mice and triggers the same signalling pathways in both species. Therefore, despite differences in the spermatogonial differentiation scheme, both species use the same genes and proteins to maintain the pool of self-renewing SSCs within their niche. Spermatocytic seminomas are mainly found in the testes of older men, and they rarely metastasize. It is believed that these tumours originate from a post-natal germ cell. Because these lesions can express markers specific for meiotic prophase, they might originate from a primary spermatocyte. However, morphological appearance and overall immunohistochemical profile of these tumours indicate that the cell of origin could also be a spermatogonial stem cell.

Comparative evaluation of neural tissue antigens--neurofilament protein (NF), peripherin (PRP), S100B protein (S100B), neuron-specific enolase (NSE) and chromogranin-A (CgA)--in both normal and inflamed human mature dental pulp

The immunohistochemical detection of neurofilament protein (NF), peripherin (PRP), S100B protein (S100B), neuron-specific enolase (NSE) and chromogranin-A (CgA) has been studied in nerve fibres and bundles of human dental pulp. This was done in order to identify possible differences in the distribution pattern of the above markers between normal and inflamed pulp and, further, to evaluate their potential use as peripheral markers of dental innervation as well as objective markers for the determination of the extent of inflammation. Both normal and inflamed human dental pulp showed positive immunolabelling for NF, S100B and NSE and lack of labelling for PRP and CgA protein. An increased density of NF, S100B and NSE immunoreactive nerve fibres was observed in inflamed pulp samples compared to non-inflamed. The findings of this study suggest the possible application of NF, S100B and NSE as markers of dental innervation. Furthermore, they may be useful for the determination of the extent of pulpal inflammation, and might be utilized in alternative modalities of biological pulp therapy to reduce the inflammation process. The absence of CgA immunolabelling implies the presumptive absence of neuroendocrine antigens, while further research is required in order to clarify the involvement of PRP in dental pulp.

Developmental model for the pathogenesis of testicular carcinoma in situ: genetic and environmental aspects

Carcinoma in situ testis (CIS), also known as intratubular germ cell neoplasia (ITGCN), is a pre-invasive precursor of testicular germ cell tumours, the commonest cancer type of male adolescents and young adults. In this review, evidence supporting the hypothesis of developmental origin of testicular germ cell cancer is summarized, and the current concepts regarding aetiology and pathogenesis of this disease are critically discussed. Comparative studies of cell surface proteins (e.g. PLAP and KIT), some of the germ cell-specific markers (e.g. MAGEA4, VASA, TSPY and NY-ESO-1), supported by studies of regulatory elements of the cell cycle (e.g. p53, CHK2 and p19-INK4d) demonstrated a close similarity of CIS to primordial germ cells and gonocytes, consistent with the pre-meiotic origin of CIS. Recent gene expression profiling studies showed that CIS cells closely resemble embryonic stem cells (ESCs). The abundance of factors associated with pluripotency (NANOG and OCT-3/4) and undifferentiated state (AP-2gamma) may explain the remarkable pluripotency of germ cell neoplasms, which are capable of differentiating to various somatic tissue components of teratomas. Impaired gonadal development resulting in the arrest of gonocyte differentiation and retention of its embryonic features, associated with an increasing genomic instability, is the most probable model for the pathogenesis of CIS. Genomic amplification of certain chromosomal regions, e.g. 12p, may facilitate survival of CIS and further invasive progression. Genetic studies, have so far not identified gene polymorphisms predisposing to the most common non-familial testicular cancer, but this research has only recently begun. Association of CIS with other disorders, such as congenital genital malformations and some forms of impaired spermatogenesis, all rising in incidence in a synchronous manner, led to the hypothesis that CIS might be a manifestation of testicular dysgenesis syndrome (TDS). The aetiology of TDS including testicular cancer remains to be elucidated, but epidemiological trends suggest a primary role for environmental factors, probably combined with genetic susceptibility.

New evidence for the origin of intracranial germ cell tumours from primordial germ cells: expression of pluripotency and cell differentiation markers

Primary intracranial germ cell tumours are rare neoplasms that occur in children and adolescents. This study examined both the biology and the origin of these tumours, as it has been hypothesized that they originate from a totipotent primordial germ cell. We applied recent knowledge from gonadal germ cell tumours and analysed expression of a wide panel of stem cell-related proteins (C-KIT, OCT-3/4 (POU5F1), AP-2gamma (TFAP2C), and NANOG) and developmentally regulated germ cell-specific proteins (including MAGE-A4, NY-ESO-1, and TSPY). Expression at the protein level was analysed in 21 children and young adults with intracranial germinomas and non-germinomas, contributing to a careful description of these unusual tumours and adding to the understanding of pathogenesis. Stem cell related proteins were highly expressed in intracranial germ cell tumours, and many similarities were detected with their gonadal equivalents, including a close similarity with primordial germ cells. A notable difference was the sex-specific expression of TSPY, a gene previously implicated in the origin of gonadoblastoma. TSPY was only detected in germ cell tumours in the central nervous system (CNS) from males, suggesting that it is not required for the initiation of malignant germ cell transformation. The expression of genes associated with embryonic stem cell pluripotency in CNS germ cell tumours strongly suggests that these tumours are derived from cells that retain, at least partially, an embryonic stem cell-like phenotype, which is a hallmark of primordial germ cells.

The immunohistochemical expression pattern of Chk2, p53, p19INK4d, MAGE-A4 and other selected antigens provides new evidence for the premeiotic origin of spermatocytic seminoma

AIMS

Spermatocytic seminoma is a rare germ cell derived tumour of the testis that occurs mainly in older men. We analysed the expression of recently discovered markers for germ cell differentiation and the mitosis-meiosis transition in order to define the antigen profile for diagnostic purposes and to clarify the biology and histogenesis of spermatocytic seminoma.

METHODS AND RESULTS

Twenty-five spermatocytic seminomas were examined for immunohistochemical expression of germ cell-specific onco-fetal antigens and proteins involved in regulation of germ cell division, DNA repair and differentiation. The panel included Chk2, p19INK4d, p53, MAGE-A4, KIT, TRA-1-60, neurone-specific enolase and placental-like alkaline phosphatase. Four of these proteins/antigens have never before been investigated in spermatocytic seminoma. Proteins highly expressed in gonocytes and spermatogonia, such as Chk2, MAGE-A4 and neurone-specific enolase, were consistently present in spermatocytic seminoma. Antigens expressed in embryonic germ cells but not in the normal adult testis, e.g. TRA-1-60, were undetectable, with the exception of p53 protein, which was demonstrated in 80% of cases. A proto-oncogene p19INK4d, which is involved in the transition from mitotic to meiotic division in germ cells, was not detected in spermatocytic seminoma.

CONCLUSIONS

The investigation provided new information concerning the expression of Chk2, MAGE-A4, neurone-specific enolase and p19INK4d in spermatocytic seminoma. The pattern of expression is highly consistent with the origin of spermatocytic seminoma from a premeiotic germ cell, which has lost embryonic traits and has committed to spermatogenic lineage but has not yet passed the meiotic checkpoint, most probably from the spermatogonium of the adult testis.

The emerging phenotype of the testicular carcinoma in situ germ cell

This review summarises the existing knowledge on the phenotype of the carcinoma in situ (CIS) cell. CIS is a common pre-invasive precursor of testicular germ cell tumours of adolescents and young adults. These tumours display a variety of histological forms. Classical seminoma proliferates along the germ cell lineage, whereas embryonal carcinoma retains embryonic features and readily differentiates into teratomas that resemble various somatic cell lineages. A thorough review of the gene expression in CIS cells in comparison to normal testicular germ cells and overt tumours supports the view that CIS is a common precursor for both tumour types. Impaired cell differentiation resulting in a partial retention of the embryonic features, associated with an increasing genomic instability may be responsible for a remarkable phenotypic heterogeneity of CIS cells. Depending on the degree of differentiation and pluripotency, CIS cells found in adult patients seem to be predestined for further malignant progression into one or the other of the two main types of overt tumours. A new concept of phenotypic continuity of differentiation of germ cells along germinal lineage with a gradual loss of embryonic features based on the analysis of gene expression in all types of germ cells during their ontogeny is presented in this review. The data point out that despite the phenotypic continuum of gene expression, there are two periods of rapid changes of gene expression: first at the transition from primordial germ cells to pre-spermatogonia, and later during the pubertal switch from the mitotic to meiotic cell division. The persistent expression of embryonic traits in CIS cells, and the high expression of the cell cycle regulators that are typical of mitotic germ cells support our long-standing hypothesis that CIS cells originate from primordial germ cells or gonocytes and not from germ cells in the adult testis.

Carcinoma in situ in the testis

Carcinoma in situ (CIS) of the testis is a common precursor of germ-cell tumours in adults and adolescents, with the exception of spermatocytic seminoma. This article reviews existing knowledge on the pathobiology, genetic aspects and epidemiology of CIS, discusses current hypotheses concerning pathogenesis and invasive progression of germ-cell neoplasms and provides guidelines for diagnosis and clinical management of CIS.

Carcinoma in situ of the testis: review of biological and clinical features

Carcinoma in situ of the testis (CIS) is the uniform precursor of testicular germ-cell tumours. Morphologically, CIS consists of large, intratubular, gonocyte-like cells with large nuclei and abundant glycogen. CIS cells are probably derived from primordial germ cells and are supposed to be present in the testis of a future testis cancer patient at the time of birth. CIS cells appear to spread inside the seminiferous tubules until CIS progresses to invasive cancer. Diagnosis is best achieved by surgical biopsy of the testis and subsequent immunohistological staining of placental alkaline phosphatase (PlAP). This enzyme is present in embryonal germ cells, CIS and seminoma as well as several other types of germ-cell tumour but usually not in normal germ cells. CIS is found in testicular tissue adjacent to testicular germ-cell tumours in about 90% of cases, and it is observed in all clinical groups known to be at risk for testicular cancer: cryptorchidism (2% to 4%), infertility (0% to 1%), ambiguous genitalia (25%) and contralateral testis of patients with testicular cancer (5%). Conversely, CIS is found in less than 1% of the normal male population, and this prevalence corresponds well to the life-time risk of testicular cancer in males. If CIS is left untreated, there is a 50% probability of progressing to frank germ-cell neoplasm within 5 years. Localised low-dose radiotherapy to the testis eradicates CIS and germ cells, while Leydig cells are preserved. The patient can thus be spared orchiectomy and hormone supplementation. Currently, dose-reduction studies are looking for the optimal radiation dose, which is expected to be around 14 to 16 Gy. After chemotherapy, there is a cumulative risk of 42% for recurrence of CIS within 10 years. The concept of CIS offers the chance of very early detection of testicular cancer and organ-preserving early treatment.