Gonadal malignant germ cell tumors express immunoreactive inhibin/activin subunits

TGF-β and microRNA Interplay in Genitourinary Cancers

Genitourinary cancers (GCs) include a large group of different types of tumors localizing to the kidney, bladder, prostate, testis, and penis. Despite highly divergent molecular patterns, most GCs share commonly disturbed signaling pathways that involve the activity of TGF-β (transforming growth factor beta). TGF-β is a pleiotropic cytokine that regulates key cancer-related molecular and cellular processes, including proliferation, migration, invasion, apoptosis, and chemoresistance. The understanding of the mechanisms of TGF-β actions in cancer is hindered by the "TGF-β paradox" in which early stages of cancerogenic process are suppressed by TGF-β while advanced stages are stimulated by its activity. A growing body of evidence suggests that these paradoxical TGF-β actions could result from the interplay with microRNAs: Short, non-coding RNAs that regulate gene expression by binding to target transcripts and inducing mRNA degradation or inhibition of translation. Here, we discuss the current knowledge of TGF-β signaling in GCs. Importantly, TGF-β signaling and microRNA-mediated regulation of gene expression often act in complicated feedback circuits that involve other crucial regulators of cancer progression (e.g., androgen receptor). Furthermore, recently published in vitro and in vivo studies clearly indicate that the interplay between microRNAs and the TGF-β signaling pathway offers new potential treatment options for GC patients.

Adult-type granulosa cell tumor of the testis: report of a case and review of literature

Granulosa cell tumors is classified into juvenile and adult types and comprise less than 5% of ovarian tumors in women and are much rarer in men which only 45 have been previously reported. We report here a 40-year young man with a left testicular adult type granulosa cell tumor. The tumor measured 5.5X5X4cm; Immunohistochemical stains showed the tumor diffusely positive for inhibin and vimentin. Post operative CT scans shows a lomboaortic lymphnodes treated by four cycles of chemotherapy type BEP (bleomycin, etoposide, cisplatin). The thoraco abdominal CT scans post chemotherapy shows the disappearance of the right testicular nodule and the lomboaortic lymphnodes. 2 years after treatment, the patient is alive and well with no signs of recurrence. Our report highlights one more case of this very rare tumor of the testis, which is quite problematic In terms of prognosis and management, and for this reason seems to have attracted the interest of many researchers recently.

High Concentrations of Activin A in the Peritoneal Fluid of Women With Epithelial Ovarian Cancer

OBJECTIVE

The aim of the present study was to evaluate the concentrations of activin A in the peritoneal fluid of women with epithelial (serous) ovarian cancer.

METHODS

A group of 160 women was studied and divided in four subgroups as follows: 1) serous ovarian carcinoma (n = 32); 2) serous ovarian cystadenoma (n = 20); 3) endometriosis (n = 53); and 4) healthy controls (n = 55), including both fertile (n = 32) and postmenopausal women (n = 23). Specimens of peritoneal fluid were collected during surgical interventions, and activin A was quantified using a specific two-site enzyme immunoassay.

RESULTS

Peritoneal fluid activin A concentrations in women with ovarian carcinoma were about five-fold higher than those found in the control group (median [interquartile range] = 7.60 [2.85-10.15] and 1.50 [1.00-2.50] ng/mL, respectively, P <.001). In contrast, the women with benign serous cystadenoma had peritoneal fluid activin A concentrations (1.50 [1.0-2.70] ng/mL) similar to those of the control group. High peritoneal fluid activin A levels (>2 multiples of the mean) distinguished carcinoma from cystadenoma with a sensitivity of 72% and a specificity of 80%. The follow-up of nine patients with stage IIIc ovarian cancer showed no apparent relationship between the peritoneal fluid activin A levels and overall survival. No significant difference in peritoneal fluid activin A concentrations between patients with endometriosis and control women was observed.

CONCLUSION

Most women with serous ovarian carcinoma had high concentrations of activin A in the peritoneal fluid, supporting a possible role of this growth factor in ovarian cancer.

Activins in reproductive biology and beyond

BACKGROUND

Activins are members of the pleiotrophic family of the transforming growth factor-beta (TGF-β) superfamily of cytokines, initially isolated for their capacity to induce the release of FSH from pituitary extracts. Subsequent research has demonstrated that activins are involved in multiple biological functions including the control of inflammation, fibrosis, developmental biology and tumourigenesis. This review summarizes the current knowledge on the roles of activin in reproductive and developmental biology. It also discusses interesting advances in the field of modulating the bioactivity of activins as a therapeutic target, which would undoubtedly be beneficial for patients with reproductive pathology.

METHODS

A comprehensive literature search was carried out using PUBMED and Google Scholar databases to identify studies in the English language which have contributed to the advancement of the field of activin biology, since its initial isolation in 1987 until July 2015. 'Activin', 'testis', 'ovary', 'embryonic development' and 'therapeutic targets' were used as the keywords in combination with other search phrases relevant to the topic of activin biology.

RESULTS

Activins, which are dimers of inhibin β subunits, act via a classical TGF-β signalling pathway. The bioactivity of activin is regulated by two endogenous inhibitors, inhibin and follistatin. Activin is a major regulator of testicular and ovarian development. In the ovary, activin A promotes oocyte maturation and regulates granulosa cell steroidogenesis. It is also essential in endometrial repair following menstruation, decidualization and maintaining pregnancy. Dysregulation of the activin-follistatin-inhibin system leads to disorders of female reproduction and pregnancy, including polycystic ovary syndrome, ectopic pregnancy, miscarriage, fetal growth restriction, gestational diabetes, pre-eclampsia and pre-term birth. Moreover, a rise in serum activin A, accompanied by elevated FSH, is characteristic of female reproductive aging. In the male, activin A is an autocrine and paracrine modulator of germ cell development and Sertoli cell proliferation. Disruption of normal activin signalling is characteristic of many tumours affecting reproductive organs, including endometrial carcinoma, cervical cancer, testicular and ovarian cancer as well as prostate cancer. While activin A and B aid the progression of many tumours of the reproductive organs, activin C acts as a tumour suppressor. Activins are important in embryonic induction, morphogenesis of branched glandular organs, development of limbs and nervous system, craniofacial and dental development and morphogenesis of the Wolffian duct.

CONCLUSIONS

The field of activin biology has advanced considerably since its initial discovery as an FSH stimulating agent. Now, activin is well known as a growth factor and cytokine that regulates many aspects of reproductive biology, developmental biology and also inflammation and immunological mechanisms. Current research provides evidence for novel roles of activins in maintaining the structure and function of reproductive and other organ systems. The fact that activin A is elevated both locally as well as systemically in major disorders of the reproductive system makes it an important biomarker. Given the established role of activin A as a pro-inflammatory and pro-fibrotic agent, studies of its involvement in disorders of reproduction resulting from these processes should be examined. Follistatin, as a key regulator of the biological actions of activin, should be evaluated as a therapeutic agent in conditions where activin A overexpression is established as a contributing factor.

Molecular characteristics of malignant ovarian germ cell tumors and comparison with testicular counterparts: implications for pathogenesis

This review focuses on the molecular characteristics and development of rare malignant ovarian germ cell tumors (mOGCTs). We provide an overview of the genomic aberrations assessed by ploidy, cytogenetic banding, and comparative genomic hybridization. We summarize and discuss the transcriptome profiles of mRNA and microRNA (miRNA), and biomarkers (DNA methylation, gene mutation, individual protein expression) for each mOGCT histological subtype. Parallels between the origin of mOGCT and their male counterpart testicular GCT (TGCT) are discussed from the perspective of germ cell development, endocrinological influences, and pathogenesis, as is the GCT origin in patients with disorders of sex development. Integrated molecular profiles of the 3 main histological subtypes, dysgerminoma (DG), yolk sac tumor (YST), and immature teratoma (IT), are presented. DGs show genomic aberrations comparable to TGCT. In contrast, the genome profiles of YST and IT are different both from each other and from DG/TGCT. Differences between DG and YST are underlined by their miRNA/mRNA expression patterns, suggesting preferential involvement of the WNT/β-catenin and TGF-β/bone morphogenetic protein signaling pathways among YSTs. Characteristic protein expression patterns are observed in DG, YST and IT. We propose that mOGCT develop through different developmental pathways, including one that is likely shared with TGCT and involves insufficient sexual differentiation of the germ cell niche. The molecular features of the mOGCTs underline their similarity to pluripotent precursor cells (primordial germ cells, PGCs) and other stem cells. This similarity combined with the process of ovary development, explain why mOGCTs present so early in life, and with greater histological complexity, than most somatic solid tumors.

SALL4 and SF-1 Are Sensitive and Specific Markers for Distinguishing Granulosa Cell Tumors From Yolk Sac Tumors

Granulosa cell tumors are classified as juvenile and adult types. They may be misinterpreted as a yolk sac tumor when they exhibit a “reticular” growth pattern and contain prominent mitotic activity. In this study, the authors performed immunohistochemical stains for SALL4 and steroidogenic factor-1 (SF-1) on 27 cases of yolk sac tumors and 24 granulosa cell tumors. Nuclear stains for both antibodies were considered as positive and the intensity of staining was graded as negative, weak, moderate, and strong. All the yolk sac tumors were positive for SALL4 (100%) with moderate to strong grade staining and negative for SF-1 (100%). In contrast, all the granulosa cell tumors were positive for SF-1 (85% moderate to strong grade staining and 15% weak staining) and negative for SALL4 (100%). The difference was significant ( P < .01, Student’s t test). This result indicates that these 2 markers could be used to distinguish these 2 tumors in a difficult situation.

A genome-wide association study of men with symptoms of testicular dysgenesis syndrome and its network biology interpretation

Background

Testicular dysgenesis syndrome (TDS) is a common disease that links testicular germ cell cancer, cryptorchidism and some cases of hypospadias and male infertility with impaired development of the testis. The incidence of these disorders has increased over the last few decades, and testicular cancer now affects 1% of the Danish and Norwegian male population.

Methods

To identify genetic variants that span the four TDS phenotypes, the authors performed a genome-wide association study (GWAS) using Affymetrix Human SNP Array 6.0 to screen 488 patients with symptoms of TDS and 439 selected controls with excellent reproductive health. Furthermore, they developed a novel integrative method that combines GWAS data with other TDS-relevant data types and identified additional TDS markers. The most significant findings were replicated in an independent cohort of 671 Nordic men.

Results

Markers located in the region of TGFBR3 and BMP7 showed association with all TDS phenotypes in both the discovery and replication cohorts. An immunohistochemistry investigation confirmed the presence of transforming growth factor β receptor type III (TGFBR3) in peritubular and Leydig cells, in both fetal and adult testis. Single-nucleotide polymorphisms in the KITLG gene showed significant associations, but only with testicular cancer.

Conclusions

The association of single-nucleotide polymorphisms in the TGFBR3 and BMP7 genes, which belong to the transforming growth factor β signalling pathway, suggests a role for this pathway in the pathogenesis of TDS. Integrating data from multiple layers can highlight findings in GWAS that are biologically relevant despite having border significance at currently accepted statistical levels.

Adult type granulosa cell tumor in adult testis: report of a case and review of the literature

Granulosa cell tumors can be classified into juvenile and adult types and more commonly occur in ovaries. Adult testicular granulosa cell tumors are extremely rare and only 29 cases of adult type have previously been reported. We report here a 28-year old Caucasian man with a left testicular adult type granulosa cell tumor. The tumor measured 2.6×2.6×2.5 cm and was mitotically active (10/10 HPF). Immunohistochemical stains showed the tumor diffusely positive for inhibin and vimentin, and negative for epithelial membrane antigen, cytokeratins, synaptophysin, HMB-45, OCT-4, placental-like alkaline phosphatase and lymphoid markers. The reported granulosa cell tumors in adult testis were briefly reviewed.

Bone morphogenetic protein signalling activity distinguishes histological subsets of paediatric germ cell tumours

Germ cell tumours (GCTs) are cancers of the testis, ovary or extragonadal sites that occur in infants, children and adults. Testicular GCT is the most common cancer in young men aged 15-40 years. Abnormalities in developmental signalling pathways such as wnt/β-catenin, TGF-β/BMP and Hedgehog have been described in many childhood tumours. To date, however, the status of BMP signalling in GCTs has not been described. Herein, we examine BMP-SMAD signalling in a set of clinically-annotated paediatric GCTs. We find that BMP signalling activity is absent in undifferentiated tumours such as seminomas and dysgerminomas, but robustly present in most yolk sac tumours, a differentiated tumour type. Gene expression profiling of TGF-β/BMP pathway genes in germinomas and yolk sac tumours reveals a set of genes that distinguish the two tumour types. There is significant intertumoural heterogeneity between tumours of the same histological subclass, implying that the BMP pathway can be differentially regulated in individual tumours. Finally, through miRNA expression profiling, we identify differential regulation of a set of miRNAs predicted to target the TGF-β/BMP pathway at multiple sites. Taken together, these results suggest that the BMP signalling pathway may represent a new therapeutical target for childhood GCTs.

Combined functional genome survey of therapeutic targets for clear cell carcinoma of the kidney

OBJECTIVE

Emerging molecular targeting therapeutics have been incorporated into the management of advanced renal cell carcinoma; however, their efficacy remains limited. The aim of this study was to catalog potential therapeutic target molecules for renal cell carcinoma.

METHODS

We first selected genes up-regulated in clear cell renal cell carcinoma relative to surrounding normal kidney tissues in 10 patients (Study Cohort) using high-density exon arrays that detect all potential transcripts predicted in the human genome. The selected genes were subjected to independent validation in another set of 10 patients (Validation Cohort) using real-time reverse transcriptase polymerase chain reaction and functional screening using small interfering RNA in six clear cell renal cell carcinoma cell lines.

RESULTS

We identified 164 genes whose expression was significantly elevated in clear cell renal cell carcinoma (P< 0.0001 [Student's t-test] and at least a 3-fold change in transcription signal). We finally extracted 33 genes required for maintaining cell proliferation in at least two clear cell renal cell carcinoma cell lines. The 33 genes included 13 genes known to be associated with the development/progression of renal cell carcinoma, including CAIX and FLT-1, confirming the robustness of the current strategy.

CONCLUSIONS

Through a combination of genome-wide expression and functional assays, we identified a set of genes with high potential as targets for drug development. This method is rapid and comprehensive and could be applied to the discovery of diagnostic biomarkers and therapeutic targets for cancers other than clear cell renal cell carcinoma.

New targets for old hormones: inhibins clinical role revisited

Inhibins are gonadal peptide hormones belonging to the transforming growth factor-β (TGF-β) superfamily that regulate the pituitary follicle stimulating hormone (FSH) secretion by negative feedback mechanisms. It is evident that the understanding of inhibins function in the hypothalamic-pituitary-gonadal axis will provide insights into physiology and pathology of the gonadal function. In recent years, a great deal of attention has been focussed on clinical relevance of measuring circulating inhibins in normal and disease state. The past few years also have witnessed the emergence and discovery of extra pituitary action of inhibins that might provide further insights into the underlying diseases like cancer especially in the reproductive axis and various other new endocrine target organs. In this review after systematic analysis of literature, we discuss briefly the known and recent advances in function of these hormones highlighting also its structure, production and mechanisms of signal transduction. Also this review discusses about the physiological relevance of inhibin association in the normal function to the development of reproductive cancers. Finally, we describe evidence from various emerging studies that inhibins make an important contribution to other physiological functions apart from reproduction which reveals new endocrine target organs of inhibins. The emerging view is inhibin participates in multiple ways to regulate the function in different cell types and still complete repertoire of its actions is under investigation.

Spermatocytic seminoma with neuroectodermal differentiation and sertoli cell tumor in a dog

Two distinct nodules developed in a cryptorchid testis of an 8-year-old male West Highland White Terrier. One nodule was a Sertoli cell tumor. The other was a spermatocytic seminoma with focal primitive neuroectodermal differentiation: formation of Homer-Wright rosettes and perivascular pseudorosettes, with immunoreactivity for S-100 protein, neuron-specific enolase, synaptophysin, neurofilament-68 kDa, microtubule-associated protein 2, and vimentin. The dog was alive and healthy 2 years after castration.

Analysis of activin/TGFB-signaling modulators within the normal and dysfunctional adult human testis reveals evidence of altered signaling capacity in a subset of seminomas

Activin is a pleiotropic growth factor belonging to the transforming growth factor-beta (TGFB) superfamily of signaling molecules. Regulated activin signaling is known to influence several steps in rodent male gamete differentiation. TGFB ligand isoforms, TGFB1-B3, also influence germ cell survival in the rodent testis at the onset of spermatogenesis and around the time of puberty. Given the importance of regulated activin and TGFB signaling in testis development and function, we sought to investigate the cellular production sites of activin/TGFB-signaling modulators in normal and dysfunctional adult human testes samples. Signaling transducers phosphorylated SMAD2/3, and signaling modulators SMAD6, MAN-1, inhibin alpha (INHA), and beta-glycan were detected in Bouins fixed, paraffin-embedded adult human testis sections using immunohistochemistry. Additional samples examined were from testicular cancer patients and from normal men subjected to gonadotropin suppression with androgen-based contraceptives. Our findings identify distinct differences between normal and gonadotropin-deprived human testis in the expression and cellular localization of activin/TGFB-signaling modulators. The presence of a nuclear phosphorylated SMAD2/3 signal in all analyzed seminoma specimens indicated active activin/TGFB signaling. Moreover, a subset of seminoma specimens exhibited selective enhanced expression of beta-glycan (4 out of 28 seminoma tumors), INHA (6 out of 28), and MAN-1 (6 out of 28), highlighting potential functional differences between individual tumors in their capacity to regulate activin/TGFB signaling. Within the heterogenous nonseminomas, expression of signaling modulators was variable and reflected the degree of somatic differentiation. Thus, synthesis of activin and TGFB-signaling modulators may be affected by spermatogenic disruption and altered hormone levels in the testis.

Genetic variation in the inhibin pathway and risk of testicular germ cell tumors

Gene-knockout studies in mice suggest that INHA, encoding a subunit of gonadotropin-regulating proteins known as inhibins, is a tumor suppressor for testicular stromal cell tumors. It is not known whether genetic variation in the inhibin pathway also influences susceptibility to testicular germ cell tumors (TGCT), the most common testicular cancer in young men. To address this question, we conducted a case-control analysis (577 cases; 707 controls) of single-nucleotide polymorphisms (SNP) in genes in the inhibin pathway among participants in the U.S. Servicemen's Testicular Tumor Environmental and Endocrine Determinants Study. Thirty-eight tagging SNPs in six genes (INHA, INHBA, INHBB, INHBC, INHBE, and SMAD4) were genotyped. Odds ratios (OR) and 95% confidence intervals (CI) relating variant genotypes to TGCT risk were calculated using unconditional logistic regression. Among White subjects, an elevated risk of TGCT was observed for carriers of the T allele of the INHA variant rs2059693 (CT genotype: OR, 1.33; 95% CI, 1.04-1.71; TT: OR, 1.60; 95% CI, 1.01-2.52; P(trend) = 0.008). The association with rs2059693 was stronger for nonseminomas, and for teratomas and teratocarcinomas in particular (N = 58; CT: OR, 1.63; 95% CI, 0.89-2.99; TT: OR, 4.54; 95% CI 2.00-10.3; P(trend) = 0.0008). We found no evidence of association with variants in the other investigated genes. These findings suggest that genetic variation in the INHA locus influences TGCT development.

The transforming growth factor-? superfamily in early spermatogenesis: potential relevance to testicular dysgenesis

Regulated transforming growth factor-beta (TGFbeta) superfamily signalling is an integral part of normal testicular development and the processes that enable the production of fertile sperm. Through shared utilization of receptors, signal transduction components and inhibitors, many ligands in this family exhibit functional overlaps; this facet of their function is critical to understand because these ligands are often co-expressed and, hence, they may compete with or compensate for one another, depending on the specific cellular context. This review describes particular germ cell maturation steps governed by bone morphogenetic proteins, glial cell line-derived neurotrophic factor and activins, focusing on data predominantly from rodent studies that implicate activin and other family members in modulation of gonocyte and spermatogonial stem cell development. We also review knowledge of the TGFbeta superfamily signalling components in the human testis, exploring their potential impact on the processes associated with disrupted gonocyte development and an enhanced risk of testicular cancer.

Inhibin as a diagnostic marker for ovarian cancer

The inhibins are a family of growth factors comprised of several different species that are secreted in the female principally from the ovarian follicle. The inhibins perform best as markers of ovarian cancer when measured collectively (total inhibin) by immunoassays targeted to common epitopes. After menopause with the depletion of ovarian follicles, the circulating level of total inhibin becomes undetectable. In contrast, serum total inhibin levels are elevated in women with ovarian cancer, in particular those with granulosa cell tumours and those with the mucinous subtype of epithelial carcinoma. Investigations into the clinical utility of inhibin to detect ovarian cancer have shown that it complements CA125, an established marker of epithelial ovarian cancer, in that each performs best in detecting different subtypes of ovarian cancer. In some published studies, the two markers together have detected up to 95% of ovarian cancers with 95% specificity.

Inhibins and ovarian cancer

The inhibins are produced and secreted by several ovarian cancers. Monitoring serum levels by immunoassay may be a useful diagnostic aid in the initial assessment of this disease and in monitoring its potential recurrence following surgery. The assays are applicable to women after menopause when the majority of ovarian cancers are detected, and when the normal ovarian production of inhibin is low to negligible. A new inhibin immunoassay (total inhibin ELISA) has been developed with the intention of widespread clinical application. The assay readily detects granulosa cell and mucinous tumours. CA125, a widely used ovarian cancer marker, detects the other main ovarian cancer types (serous, endometrioid, undifferentiated) with high sensitivity. The combination of the two tests detects the majority of ovarian cancers with high specificity (95%) and sensitivity (95%). Studies have been undertaken to assess its application to women in the perimenopausal stage and to younger women during normal reproductive life. These studies are providing a platform for the introduction of the test into clinical practice.

Chromosomes, genes, and development of testicular germ cell tumors

A literature review found 265 articles on testicular germ cell tumors (TGCTs) detailing the copy number of chromosomal regions and expression of 245 genes. An initial precursor stage, intratubular germ cell neoplasia (IGCN), is characterized by triploidization and an upregulation of KIT, ALPP, CCDN2, and ZNF354A, and a downregulation of CDKN2D. TGCT regularly have a series of chromosomal aberrations: a decrease in copy number at 4q21 approximately qter and 5q14 approximately qter; an increase at 7p21 approximately pter, 7q21 approximately q33, and 8q12 approximately q23 (especially high increase in seminoma); a decrease at 11p11 approximately p15 and 11q14 approximately q24; an increase at 12p11 approximately pter; a decrease at 13q14 approximately q31; an increase of 17q11 approximately q21 (only for nonseminoma); a decrease of 18q12 approximately qter; and an increase at 21q21 approximately qter, 22q11 approximately qter (only for seminoma), and Xq. Macroscopically overt TGCT is associated with a characteristic series of abnormalities in the retinoblastoma pathway including upregulation of cyclin D2 and p27 and downregulation of RB1 and the cyclin-dependent kinase inhibitors p16, p18, p19, and p21. TGCT thus has a synergistic pattern in gene expressions of the retinoblastoma pathway that is rare in other malignancies.

Growth regulatory factors and signalling proteins in testicular germ cell tumours

The molecular basis of testicular germ cell tumourigenesis are not well elucidated. Growth factors regulate cell growth, differentiation and apoptosis. Major families of growth factors are present in the male gonad from early fetal development to adult life. They are involved in germ cell proliferation and differentiation. Growth signalling pathways suffer deregulation in many human malignancies. Given the importance of growth signals in normal testicular development and their acquired deregulation in most human cancers, growth factors and signalling molecules that have been implicated in the genesis of testicular germ cell tumours, are reviewed. We detected a somatic mutation of SMAD4 gene, responsible for loss of protein function in seminomas. This mutational inactivation may affect the activity of several members of TGFbeta superfamily (TGFbeta, activin, inhibin, BMP). VEGF expression has been shown to predict metastasis in seminomas. A significant association of HST-1 expression, a member of fibroblast growth factors, with the nonseminomatous phenotype and with tumour stage has been described. In contrast, C-KIT is expressed by seminomas only, from the preinvasive stage. Despite intense expression in almost all seminomas, activating mutation of C-KIT gene is seldom reported. Recently, the first animal model of classical testicular seminoma has been identified in transgenic mouse overexpressing GDNF. RET (GDNF receptor) expression is demonstrated in human seminomas, and not in nonseminomatous tumours. However, the exact molecular alterations of GDNF/RET/GFRalpha1 complex in germ cell tumours are not known. Finally, beside growth factors, other signalling molecules such as peptide hormones may be involved in testicular carcinogenesis. We have demonstrated a specific pattern of somatostatin receptors expression in each type of testicular germ cell tumours, with a loss of sst3 and sst4 in seminomas and loss of sst4 and expression of sst1 in nonseminomas only. These data suggest an antiproliferative action of somatostatin in testicular cancers. In summary, many growth factors and signalling molecules seem to represent specific markers for different histological types of germ cell tumours (seminomas versus nonseminomas) and may play a role in the differentiation of germ cell tumours. Despite a complex signalling pathway involved in the physiological functions of male gonad, little is known about the implication of this signalling network in testicular malignancies. From a practical stand-point, further studies on the role of growth factors in human germ cell tumours may offer a new therapeutical perspective with the development of specific pharmacological signalling modulators that could be used as therapeutic agents.

Inhibin immunohistochemical staining: a practical approach for the surgical pathologist in the diagnoses of ovarian sex cord-stromal tumors

Through a brief introduction of inhibin history, characteristics of the antibody against inhibin, and normal tissue distribution of alpha-inhibin expression, this comprehensive review focuses on a practical approach to using alpha-inhibin in the differential diagnosis of ovarian sex cord-stromal tumors (SCSTs). Alpha-inhibin has become a most useful immunohistochemical marker of gonadal SCST, regardless if the tumors are primary, recurrent, or metastatic. However, pathologic diagnosis of individual SCST is still based largely on morphologic criteria. Alpha-inhibin immunohistochemical (IHC) staining should be used only when a difficult morphologic diagnosis is encountered. In this perspective, alpha-inhibin and other properly selected markers should be ordered at the same time. This is simply because alpha-inhibin is not specific for SCSTs. Caution should be exercised in the interpretation of alpha-inhibin-positive cells, because a wide variety of primary and metastatic ovarian tumors may contain significant numbers of alpha-inhibin-positive stromal cells. As with other immunohistochemical stains, a panel of stains and comparison with the corresponding hematoxylin and eosin (H&E) slides is necessary, especially when staining patterns and cellular localization are in question. The antibody will not help to differentiate tumors within the category of SCST. The pattern or the intensity of staining in SCSTs does not predict tumor behavior, although there is a tendency of loss of alpha-inhibin expression in poorly differentiated Sertoli or Sertoli-Leydig cell tumors. In cases where metastatic granulosa or Sertoli-Leydig cell tumors are a concern, positive alpha-inhibin staining is diagnostic, but a negative result does not rule out metastatic disease. Calretinin has been recently recognized as a more sensitive, but less specific marker for SCSTs and it may be used to recognize an inhibin-negative SCST. In this review, we have listed nine of the most commonly encountered clinical scenarios where alpha-inhibin and other markers could be used in diagnostic surgical pathology of ovarian tumors.