Oncofetal protein glypican-3 in testicular germ-cell tumor

Administration of a glypican-3 peptide increases the infiltration and cytotoxicity of CD8+ T cells against testicular yolk sac tumor, associated with enhancing the intratumoral cGAS/STING signaling

BACKGROUND

Glypican-3 (GPC3) is highly expressed in testicular yolk sac tumor (TYST). GPC3 has been evaluated as a cancer vaccine for some types of tumors, but little is known on the effects of GPC3 peptide-based therapy on TYST. Here, we evaluated the antitumor effect of GPC3144-152 on TYST and its potential mechanisms.

METHODS

GPC3144-152 -specific CD8+ T cells were induced by vaccine immunization and examined by ELISPOT. The CD8+ T cells were purified for testing their cytotoxicity in vitro against TYST cells by CCK-8 and TUNEL assays and in vivo against tumor growth. The influence of GPC3144-152 loading and/or cGAS silencing on the tumor growth, apoptosis and cGAS/STING signaling was tested by immunohistochemistry, immunofluorescence, flow cytometry, and Western blot.

RESULTS

Vaccination with GPC3144-152 induced tumor-specific CD8+ T cells that secreted high levels of IFN-γ and granzyme B, and had potent cytotoxicity against TYST in a dose-dependent manner. Adoptive transfer of CD8+ T cells and treatment with GPC3144-152 significantly inhibited the growth of TYST tumors, but less effective for cGAS-silenced TYST tumors in vivo. Treatment with GPC3144-152 enhanced the infiltration of CD8+ T cells into the tumor environment and their cytotoxicity against TYST tumors in vivo by up-regulating granzyme B and IFN-β expression, but down-regulating GPC3 expression in the tumors. Co-culture of CD8+ T cells with TYST in the presence of exogenous GPC3144-152 enhanced peptide-specific CD8+ T-cell cytotoxicity in vitro, accompanied by enhancing cGAS, γH2AX, TBK1, and IRF3 phosphorylation in TYST cells, but less effective in cGAS-silenced TYST cells.

CONCLUSIONS

These data indicated that GPC3 peptide-specific CD8+ T cells had potent antitumor activity against TYST tumor, particularly for combined treatment with the peptide, which was partially dependent on the intratumoral cGAS/STNG signaling. GPC3 peptide vaccine may be valuable for the combination treatment of TYST.

Paradoxical Expression of R-10G-reactive Antigen in Human Testicular Embryonal Carcinoma

Thus far, several monoclonal antibodies directed against cell-surface carbohydrate antigens have been generated. Among them, R-10G reportedly reacts selectively with human embryonic stem and induced pluripotent stem cells, but not with embryonal carcinoma (EC) cells. However, EC cells derived from patients' EC tumors may exhibit varying levels of R-10G-reactive antigen expression. Thus, we asked whether human EC tissues or germ cell tumor (GCT) tissues other than EC express R-10G-reactive antigen. To do so, we quantitatively analyzed R-10G-reactive antigen expression in 83 testicular GCT surgical specimens containing a total of 125 various GCT components. Accordingly, in all EC components examined, the EC cell plasma membrane was immunolabeled with R-10G, while most seminoma components were R-10G-negative. In non-seminomatous GCT (NSGCT) other than EC (non-EC NSGCT), R-10G-reactive antigen expression was variable, but signal distribution was focal, and the average intensity was weaker than that seen in EC. The percentages of R-10G-positive cells in these three groups varied with high statistical significance (p<0.001 for all combinations). These findings indicate that the R-10G-reactive antigen is preferentially expressed in human testicular EC tissues and, thus, could be used as a diagnostic marker for this malignancy.

The extracellular matrix in hepatocellular carcinoma: Mechanisms and therapeutic vulnerability

The tumor microenvironment (TME) is influenced by a "disorganized" extracellular matrix (ECM) that sensitizes cancer cells toward mechanical stress, signaling, and structural alterations. In hepatocellular carcinoma (HCC), lack of knowledge about key ECM proteins driving the TME refractory to targeted therapies poses a barrier to the identification of new therapeutic targets. Herein, we discuss the contributions of various ECM components that impact hepatocytes and their surrounding support network during tumorigenesis. In addition, the underpinnings by which ECM proteins transduce mechanical signals to the liver TME are detailed. Finally, in view of the bidirectional feedback between the ECM, transformed hepatocytes, and immune cells, we highlight the potential role of the ECM disorganization process in shaping responses to immune checkpoint inhibitors and targeted therapies. Our comprehensive characterization of these ECM components may provide a roadmap for innovative therapeutic approaches to restrain HCC.

Pure post-pubertal yolk sac tumor of the testis: An extremely rare and aggressive entity

CONTEXT

Pure post-pubertal yolk sac tumors (YSTs) are an extremely rare type of malignant germ cell tumor (GCT) that account for <1 % of testicular GCTs. Clinically, they are more aggressive compared to the more common pre-pubertal counterpart. The aim of this study is to analyze the clinical presentation, ancillary tests and clinical outcomes in addition to presenting a spectrum of histomorphological features, in a case series along with a literature review.

DESIGN

A retrospective review of 4 cases of pure post-pubertal YST of the testis was performed. Data collected for each patient included demographics, clinical presentation, serum markers, radiology and pathologic findings, treatment, and clinical outcomes.

RESULTS

All patients presented with a testicular mass with or without associated pain and elevated serum alpha-feto protein. Mean age at presentation was 36 years (range 25-68 years). Two patients presented with metastatic disease at the time of diagnosis. Histologic patterns and features are as follows: germ cell neoplasia in-situ (n = 4), reticular/microcystic, solid, glandular, papillary, endometrioid, cystic, necrosis and angiolymphatic invasion (n = 3). Fluorescent in-situ hybridization test performed on Case 2, showed presence of isochromosome 12p and next generation sequencing showed gains of 12p. Case 1, 2 and 4 showed metastatic disease on follow-up.

CONCLUSIONS

Diagnosis of pure post-pubertal YST remains challenging due to the variety of morphologic patterns often present in these tumors. Extensive sampling along with use of ancillary tests is the key for diagnosis. In this study, 75 % of cases had metastatic disease at or after the diagnosis confirming the aggressive nature of this rare entity.

An update on diagnostic tissue-based biomarkers in testicular tumors

Testicular cancer is rare overall but comprises the most common solid malignancy diagnosed in young men aged ∼20-40 years. Most testicular neoplasms generally fall into 2 broad categories: germ cell tumors (GCTs; ∼95%) and sex cord-stromal tumors (SCSTs ∼5%). Given the relative rarity of these tumors, diagnostic biomarkers are highly relevant for their diagnosis. Over the past several decades, diagnostic biomarkers have improved dramatically through targeted immunohistochemical and molecular characterization. Despite these recent advances, most markers are not perfectly sensitive or entirely specific. Therefore, they need to be used in combination and interpreted in context. In this review, we summarize tissue-based biomarkers relevant to the pathologist, with a focus on practical diagnostic issues that relate to testicular GCT and SCST.

Proteoglycans in Cancer: Friends or Enemies? A Special Focus on Hepatocellular Carcinoma

Simple Summary

Proteoglycans affect multiple molecular and cellular processes during the progression of solid tumors with a highly desmoplastic stroma, such as HCC. Due to their role in enhancing or limiting the traits of cancer cells underlying their aggressiveness, such as proliferation, angiogenesis, epithelial to mesenchymal transition (EMT), and stemness, these macromolecules could be exploited as molecular targets or therapeutic agents. Proteoglycans, such as biglycan, versican, syndecan-1, glypican-3, and agrin, promote HCC cell proliferation, EMT, and angiogenesis, while endostatin and proteoglycan 4 were shown to impair cancer neovascularization or to enhance the sensitivity of HCC cells to drugs, such as sorafenib and regorafenib. Based on this evidence, interventional strategies involving the use of humanized monoclonal antibodies, T cells engineered with chimeric antigen receptors, or recombinant proteins mimicking potentially curative proteoglycans, are being employed or may be adopted in the near future for the treatment of HCC.

Abstract

Proteoglycans are a class of highly glycosylated proteins expressed in virtually all tissues, which are localized within membranes, but more often in the pericellular space and extracellular matrix (ECM), and are involved in tissue homeostasis and remodeling of the stromal microenvironment during physiological and pathological processes, such as tissue regeneration, angiogenesis, and cancer. In general, proteoglycans can perform signaling activities and influence a range of physical, chemical, and biological tissue properties, including the diffusivity of small electrolytes and nutrients and the bioavailability of growth factors. While the dysregulated expression of some proteoglycans is observed in many cancers, whether they act as supporters or limiters of neoplastic progression is still a matter of controversy, as the tumor promoting or suppressive function of some proteoglycans is context dependent. The participation of multiple proteoglycans in organ regeneration (as demonstrated for the liver in hepatectomy mouse models) and in cancer suggests that these molecules actively influence cell growth and motility, thus contributing to key events that characterize neoplastic progression. In this review, we outline the main roles of proteoglycans in the physiology and pathology of cancers, with a special mention to hepatocellular carcinoma (HCC), highlighting the translational potential of proteoglycans as targets or therapeutic agents for the treatment of this disease.

Recombinant immunotoxin targeting GPC3 is cytotoxic to H446 small cell lung cancer cells

Glypican-3 (GPC3) is a cell membrane glycoprotein that regulates cell growth and proliferation. Aberrant expression or distribution of GPC3 underlies developmental abnormalities and the development of solid tumours. The strongest evidence for the participation of GPC3 in carcinogenesis stems from studies on hepatocellular carcinoma and lung squamous cell carcinoma. To the best of our knowledge, the role of the GPC3 protein and its potential therapeutic application have never been studied in small cell lung carcinoma (SCLC), despite the known involvement of associated pathways and the high mortality caused by this disease. Therefore, the aim of the present study was to examine GPC3 targeting for SCLC immunotherapy. An immunotoxin carrying an anti-GPC3 antibody (hGC33) and Pseudomonas aeruginosa exotoxin A 38 (PE38) was generated. This hGC33-PE38 protein was overexpressed in E. coli and purified. ADP-ribosylation activity was tested in vitro against eukaryotic translation elongation factor 2. Cell internalisation ability was confirmed by confocal microscopy. Cytotoxicity was analysed by treating liver cancer (HepG2, SNU-398 and SNU-449) and lung cancer (NCI-H510A, NCI-H446, A549 and SK-MES1) cell lines with hGC33-PE38 and estimating viable cells number. A BrdU assay was employed to verify anti-proliferative activity of hGC33-PE38 on treated cells. Fluorescence-activated cell sorting was used for the detection of cell membrane-bound GPC3. The hGC33-PE38 immunotoxin displayed enzymatic activity comparable to native PE38. The protein was efficiently internalised by GPC3-positive cells. Moreover, hGC33-PE38 was cytotoxic to HepG2 cells but had no effect on known GPC3-negative cell lines. The H446 cells were sensitive to hGC33-PE38 (IC₅₀, 70.6±4.6 ng/ml), whereas H510A cells were resistant. Cell surface-bound GPC3 was abundant on the membranes of H446 cells, but absent on H510A. Altogether, the present findings suggested that GPC3 could be considered as a potential therapeutic target for SCLC immunotherapy.

Clinical Applications of Immunohistochemistry in Germ Cell Tumors in Men

Germ cell tumors (GCT) in men comprise of tumor subtypes with distinct histomorphologies, genetic and genomic alterations, and clinical behavior. Immunohistochemical (IHC) markers, including many newly described nuclear transcription factors, are often applied in challenging cases to arrive at a correct diagnosis and classification, and to establish germ cell origin for metastatic tumors. However, there is no established role for IHC markers in prognosis and therapy response prediction in GCTs. This chapter briefly reviews the clinical utility of IHC in diagnosis and classification of GCTs, including technical aspects of performing IHC and clinical applications of commonly used IHC markers in the workup of common and clinically relevant diagnostic scenarios.

SALL4 is a useful marker for pediatric yolk sac tumors

BACKGROUND

SALL4 is a zinc finger transcription factor that exerts its physiological role during embryo-fetal development. Analyses of SALL4 expression have shown its oncogenic role in precursor B-cell lymphoblastic lymphoma, acute and chronic myeloid leukemia, gastrointestinal, breast, and lung cancers. The aim of this study was to determine the immunohistochemical profile of SALL4 in pediatric yolk sac tumors (YSTs).

METHODS AND RESULTS

Immunohistochemistry detection of SALL4 was performed in 22 cases of pediatric YSTs and 10 mature teratomas. The percentage of tumor cells stained was scored as 0, 1+ (1-30% cells), 2+ (31-60%), 3+ (61-90%), and 4+ (> 90%). To compare its sensitivity and specificity with Glypican-3 and α-fetoprotein (AFP), we also stained tumors from these cases for Glypican-3 and AFP. In contrast to AFP and glypican-3, SALL4 staining in more than 90% of the tumor cells was seen in all 22 pediatric YSTs (100% sensitivity) (P < 0.001 for both SALL4 vs. AFP and SALL4 vs. glypican-3).

CONCLUSIONS

SALL4 is a sensitive marker for pediatric YSTs and it can be used to distinguish them from mature teratomas. SALL4 is likely to become a new and valuable biomarker for the diagnosis of pediatric YST.

Testicular germ cell tumor: a comprehensive review

Testicular tumors are the most common tumors in adolescent and young men and germ cell tumors (TGCTs) account for most of all testicular cancers. Increasing incidence of TGCTs among males provides strong motivation to understand its biological and genetic basis. Gains of chromosome arm 12p and aneuploidy are nearly universal in TGCTs, but TGCTs have low point mutation rate. It is thought that TGCTs develop from premalignant intratubular germ cell neoplasia that is believed to arise from the failure of normal maturation of gonocytes during fetal or postnatal development. Progression toward invasive TGCTs (seminoma and nonseminoma) then occurs after puberty. Both inherited genetic factors and environmental risk factors emerge as important contributors to TGCT susceptibility. Genome-wide association studies have so far identified more than 30 risk loci for TGCTs, suggesting that a polygenic model fits better with the genetic landscape of the disease. Despite high cure rates because of its particular sensitivity to platinum-based chemotherapy, exploration of mechanisms underlying the occurrence, progression, metastasis, recurrence, chemotherapeutic resistance, early diagnosis and optional clinical therapeutics without long-term side effects are urgently needed to reduce the cancer burden in this underserved age group. Herein, we present an up-to-date review on clinical challenges, origin and progression, risk factors, TGCT mouse models, serum diagnostic markers, resistance mechanisms, miRNA regulation, and database resources of TGCTs. We appeal that more attention should be paid to the basic research and clinical diagnosis and treatment of TGCTs.

Glypican-3 expression in malignant small round cell tumors

Malignant small round cell tumors usually progress rapidly and show resistance to chemotherapy, and it is often difficult to make a definitive diagnosis based on their histological morphology. Glypican-3 (GPC3) is a highly tumor-specific antigen, and the overexpression of GPC3 was reported in many pediatric and adult malignancies. In the present study, we investigated the GPC3 expression in pediatric malignant small round cell tumors to assess its role in the differential diagnosis of the tumors. Immunohistochemistry was performed to assess the expression of GPC3 in samples from 84 rhabdomyosarcomas (RMSs; 44 alveolar and 40 embryonal RMSs), 62 Ewing sarcomas (EWSs), 35 neuroblastomas (NBs) and two desmoplastic small round cell tumors (DSRCTs). We performed a reverse transcription-quantitative polymerase chain reaction for GPC3 to determine the GPC3 mRNA expression in samples from 66 frozen tumors (23 RMSs, 28 EWSs and 15 NBs). The serum expression levels of GPC3 were analyzed in pre-operative blood samples from two RMS and eight NB patients. In total, 25% (21/84) of the RMSs and 3% (1/35) of the NBs exhibited a focal expression of GPC3, whereas, the other specimens showed no GPC3 expression. The GPC3 mRNA expression level of the RMSs with positive GPC3 expression (n=6) was significantly higher compared with the RMSs without such expression (n=17). A total of two cases of NB showed high serum levels of GPC3, but neither tumor showed immunoreactivity for GPC3. The immunohistochemical overexpression of GPC3 may be a candidate ancillary parameter in the differential diagnosis of RMS from EWS and DSRCT.

Pitfalls in the interpretation of specimens from patients with testicular tumours, with an emphasis on variant morphologies

Accurate diagnosis of primary and metastatic tumours is essential in testicular cancer. While many cases are straightforward, some pose difficulties, especially when variant morphologies occur. Seminoma with 'atypical' features, including increased nuclear pleomorphism and crowding and greater cytoplasmic density with loss of membrane definition, mimics embryonal carcinoma, although ancillary features (fibrous septa, lymphocytes) and immunohistochemistry are of great help. Other deceptive seminoma features include prominent to exclusive intertubular growth, microcystic/tubular patterns, and signet-ring tumour cells. Conversely, embryonal carcinomas may have 'seminoma-like' foci, as may Sertoli cell tumours with diffuse growth and pale cytoplasm. Solid pattern yolk sac tumour mimics seminoma and, conversely, microcytic seminoma resembles yolk sac tumour. Other architectural patterns, ancillary yolk sac tumour features (intercellular basement membrane deposits, hyaline cytoplasmic globules) and immunohistochemistry aid in distinction from seminoma. Embryonal carcinomas may show, in addition to 'seminoma-like' foci, pseudoendodermal sinus-like structures, sieve-like patterns, endometrioid-like morphology and prominent zones of stratified columnar tumour cells. These may cause confusion with yolk sac tumour and teratoma, although careful attention to cytological features usually suffices for accurate diagnosis. Recent work has defined 'new' primary trophoblastic tumours, i.e., cystic trophoblastic tumour and epithelioid trophoblastic tumour. The newly termed 'spermatocytic tumour' occasionally consists mostly of a monotonous proliferation of intermediate-sized tumour cells with prominent nucleoli, thereby simulating either seminoma or embryonal carcinoma. Prostatic adenocarcinoma remains the most common tumour to metastasise to the testis and can cause confusion with rete carcinomas and primary germ cell tumours. Post-chemotherapy resections pose their own challenges. Effete tumour cells in areas of necrosis and prominent fibroxanthomatous reactions should not be interpreted as persistent, viable germ cell tumour. 'Fibrosis' often has atypical widely scattered spindle tumour cells in a densely collagenous background but does not merit additional treatment apart from excision. The marked cytological atypia that may occur in metastatic teratoma may be disconcerting but, again, the proper treatment is complete surgical excision rather than more chemotherapy. Glandular and sarcomatoid yolk sac tumours, which are almost exclusively seen after chemotherapy, resemble adenocarcinomas and sarcomas, respectively. Unlike de novo malignancies, they are mostly seen in sites expected for metastases.

Perinatal Case of Fatal Simpson-Golabi-Behmel Syndrome with Hyperplasia of Seminiferous Tubules

Patient: Male, newborn

Final Diagnosis: Simpson-Golabi-Behmel syndrome

Symptoms: Dyspnea

Medication: —

Clinical Procedure: —

Specialty: Pediatrics and Neonatology

Identifying functional cancer-specific miRNA-mRNA interactions in testicular germ cell tumor

Testicular cancer is the most common cancer in men aged between 15 and 35 and more than 90% of testicular neoplasms are originated at germ cells. Recent research has shown the impact of microRNAs (miRNAs) in different types of cancer, including testicular germ cell tumor (TGCT). MicroRNAs are small non-coding RNAs which affect the development and progression of cancer cells by binding to mRNAs and regulating their expressions. The identification of functional miRNA-mRNA interactions in cancers, i.e. those that alter the expression of genes in cancer cells, can help delineate post-regulatory mechanisms and may lead to new treatments to control the progression of cancer. A number of sequence-based methods have been developed to predict miRNA-mRNA interactions based on the complementarity of sequences. While necessary, sequence complementarity is, however, not sufficient for presence of functional interactions. Alternative methods have thus been developed to refine the sequence-based interactions using concurrent expression profiles of miRNAs and mRNAs. This study aims to find functional cancer-specific miRNA-mRNA interactions in TGCT. To this end, the sequence-based predicted interactions are first refined using an ensemble learning method, based on two well-known methods of learning miRNA-mRNA interactions, namely, TaLasso and GenMiR++. Additional functional analyses were then used to identify a subset of interactions to be most likely functional and specific to TGCT. The final list of 13 miRNA-mRNA interactions can be potential targets for identifying TGCT-specific interactions and future laboratory experiments to develop new therapies.

Proteoglycans in liver cancer

Proteoglycans are a group of molecules that contain at least one glycosaminoglycan chain, such as a heparan, dermatan, chondroitin, or keratan sulfate, covalently attached to the protein core. These molecules are categorized based on their structure, localization, and function, and can be found in the extracellular matrix, on the cell surface, and in the cytoplasm. Cell-surface heparan sulfate proteoglycans, such as syndecans, are the primary type present in healthy liver tissue. However, deterioration of the liver results in overproduction of other proteoglycan types. The purpose of this article is to provide a current summary of the most relevant data implicating proteoglycans in the development and progression of human and experimental liver cancer. A review of our work and other studies in the literature indicate that deterioration of liver function is accompanied by an increase in the amount of chondroitin sulfate proteoglycans. The alteration of proteoglycan composition interferes with the physiologic function of the liver on several levels. This article details and discusses the roles of syndecan-1, glypicans, agrin, perlecan, collagen XVIII/endostatin, endocan, serglycin, decorin, biglycan, asporin, fibromodulin, lumican, and versican in liver function. Specifically, glypicans, agrin, and versican play significant roles in the development of liver cancer. Conversely, the presence of decorin could potentially provide protective effects.

HMGA2 expression distinguishes between different types of postpubertal testicular germ cell tumour

The group of postpubertal testicular germ cell tumours encompasses lesions with highly diverse differentiation – seminomas, embryonal carcinomas, yolk sac tumours, teratomas and choriocarcinomas. Heterogeneous differentiation is often present within individual tumours and the correct identification of the components is of clinical relevance. HMGA2 re‐expression has been reported in many tumours, including testicular germ cell tumours. This is the first study investigating HMGA2 expression in a representative group of testicular germ cell tumours with the highly sensitive method of quantitative real‐time PCR as well as with immunohistochemistry. The expression of HMGA2 and HPRT was measured using quantitative real‐time PCR in 59 postpubertal testicular germ cell tumours. Thirty specimens contained only one type of tumour and 29 were mixed neoplasms. With the exception of choriocarcinomas, at least two pure specimens from each subgroup of testicular germ cell tumour were included. In order to validate the quantitative real‐time PCR data and gather information about the localisation of the protein, additional immunohistochemical analysis with an antibody specific for HMGA2 was performed in 23 cases. Expression of HMGA2 in testicular germ cell tumours depended on the histological differentiation. Seminomas and embryonal carcinomas showed no or very little expression, whereas yolk sac tumours strongly expressed HMGA2 at the transcriptome as well as the protein level. In teratomas, the expression varied and in choriocarcinomas the expression was moderate. In part, these results contradict data from previous studies but HMGA2 seems to represent a novel marker to assist pathological subtyping of testicular germ cell tumours. The results indicate a critical role in yolk sac tumours and some forms of teratoma.

Expression of Glypican 3 in low and high grade urothelial carcinomas

Background

Glypican-3 (GPC3) is an oncofetal protein which is encoded by GPC3 gene and takes role in the regulation of cell division and apoptosis. Overexpression of GPC3 has been reported in some types of cancer such as hepatocellular carcinoma (HCC), melanoma, squamous cell carcinoma of the lungs and testicular germ cell tumors. The aim of this study was to investigate the immunohistochemical expression of GPC3 in the non-neoplastic urothelium and in urothelial carcinoma (UC). We also aimed to explore the alterations in the GPC3 expression according to the grade and the invasiveness of UC.

Methods

GPC3 expression was studied in 108 UC cases by using immunohistochemistry. Each section was evaluated in terms of the extensiveness and intensity of GPC3 staining. Scores of immunostaining were correlated with tumor grade and stage.

Results

GPC3 expression was observed in 38 cases (35.2%). GPC3 expression was positive in 43.6% of high and in 13.3% of low grade UC (p: 0.003). In 19 UC cases biopsy also harbored non-neoplastic urothelium which showed no staining for GPC3. The difference in staining percentages between low and high grade UCs, suggests that GPC3 staining could be used as an adjunctive marker in cases where the distinction between the low and high grade tumors is difficult. In addition, lack of staining in the non-neoplastic urothelial areas in 19 cases raises the possibility of the use of GPC3 staining for the distinction between neoplastic and non-neoplastic urothelium, especially in punch biopsy samples.

Conclusions

Based on our results potential role of GPC3 in urothelial carcinogenesis warrants further investigation, especially the potential use of GPC3 for therapeutic and diagnostic purposes.

Virtual Slides

The virtual slide(s) for this article can be found here: http://www.diagnosticpathology.diagnomx.eu/vs/2260833001522844

CK19 is a sensitive marker for yolk sac tumours of the testis

Background

Malignant germ cell tumours are the most common malignant tumours in young men. They are histologically divided into seminomas and non-seminomas. Non-seminomas are further subdivided into embryonic carcinomas, yolk sac tumours, chorionic carcinomas, and teratomas. For the therapeutic management it is essential to differentiate between these histological subtypes.

Methods

Investigated cases included normal testis (n = 50), intratubular germ cell neoplasia (n = 25), seminomas (n = 67), embryonic carcinomas (n = 56), yolk sac tumours (n = 29), chorionic carcinomas (n = 2), teratomas (n = 7) and four metastases of YST’s for their CK19 expression. In addition Leydig cell- (n = 10) and Sertoli cell- tumours (n = 4) were included in this study.

Results

All investigated seminomas, embryonic carcinomas as well as normal testis and intratubular germ cell neoplasias did not express CK19. In contrast, all investigated yolk sac tumours strongly expressed CK19 protein. These findings became also evident in mixed germ cell tumours consisting of embryonic carcinomas and yolk sac tumours, although CK19-expression could also be observed in analysed chorionic carcinomas and epithelial components of teratomas.

Conclusion

CK19 proved to be a sensitive marker to identify yolk sac tumours of the testis and to distinguish them from other germ cell tumours, especially seminomas and embryonic carcinomas.

Virtual slides

The virtual slide(s) for this article can be found here: http://www.diagnosticpathology.diagnomx.eu/vs/4075546891400979.

[Non-seminomatous germ cell tumours]

The group of non-seminomatous germ cell tumors can be morphologically and therapeutically distinguished from the group of seminomas. The group of non-seminomatous germ cell tumors includes embryonal carcinoma, yolk sac tumor, choriocarcinoma and teratoma. All entities can occur rarely in pure form or much more commonly in mixed germ cell tumors consisting of more than one histological type. The non-seminomatous germ cell tumors are also characterized by the appearance of an isochromosome 12p, i(12p) and arise from a common precursor lesion called intratubular germ cell neoplasia of the unclassified type (ITGCNU). Various immunohistochemical markers are used to distinguish the different tumor components in addition to morphological characteristics.

The Application of Immunohistochemical Biomarkers in Urologic Surgical Pathology

Context

Tumors of the genitourinary tract can be diagnostically challenging, particularly in core biopsies and cystoscopic biopsies with limited material. Immunohistochemistry is a valuable tool to use when morphology alone is insufficient for diagnosis.

Objectives

To review tumors and benign lesions of the kidney, urinary bladder, prostate gland, testis, and paratesticular structures with an emphasis on difficult differential diagnoses, as well as staining patterns in normal tissue. Recommended immunohistochemical stain panels are discussed that can assist in the diagnostic workup.

Data Sources

Review of current literature.

Conclusions

Immunohistochemistry is a valuable tool, assisting in the diagnosis of problematic tumors and benign lesions of the genitourinary tract.

Discovery and diagnostic value of a novel oncofetal protein: glypican 3

Glypican 3 is a membrane-bound heparan sulfate proteoglycan, which has recently been identified as a marker for liver cancer and germ cell malignancies. Individuals with loss-of-function mutations for the glypican 3 gene exhibit Simpson-Golabi-Behmel syndrome, a rare X-linked overgrowth disorder. Expression of glypican 3 mRNA and protein is normally silenced in most adult organs and may reappear during malignant transformation. In the past few years, immunohistochemical and molecular characteristics of glypican 3 in hepatocellular carcinoma have been elucidated. More recently, glypican 3 has been emerging as a new diagnostic marker for germ cell tumors and especially testicular and ovarian yolk sac tumors. However, in other tumors such as renal cell carcinomas, squamous cell carcinomas, and melanomas, studies disagree on the level of glypican 3 expression. Finally, there is the controversial notion of glypican 3 as a tumor suppressor gene. In this review article, we update current knowledge on glypican 3 expression in normal and neoplastic tissues, evaluate its utility as a tumor marker in clinical practice, and explore its role as a novel oncofetal protein with clinical implications. Our focus is on the diagnostic value of glypican 3 in germ cell tumors and other neoplasms in addition to hepatocellular carcinoma. In conclusion, glypican 3 has been proven to be a useful immunohistochemical marker in distinguishing yolk sac tumors, choriocarcinomas, and Wilms tumors from other malignancies histologically mimicking these primitive tumors. Clinically, we recommend that glypican 3 be used as part of a panel of markers in subtyping testicular germ cell tumors.

Immunohistochemical expression of SALL4 in hepatocellular carcinoma, a potential pitfall in the differential diagnosis of yolk sac tumors

SALL4 is a transcription factor that serves as a marker of yolk sac tumor. Yolk sac tumor and hepatocellular carcinoma share histologic, serologic, and immunohistochemical features. Previous studies have shown lack of SALL4 expression in hepatocellular carcinoma, suggesting utility in this differential diagnosis. Sixty-nine samples of hepatocellular carcinoma were retrieved from surgical pathology archives and used to construct 9 tissue microarrays. A germ cell tumor tissue microarray containing 10 yolk sac tumors was used for comparison. Extent, intensity, and pattern of nuclear SALL4 expression were assessed in each spot. Mean percentage of expression was calculated for each tumor and used during analysis. Optimal discriminatory extent of expression cutoff was determined by receiver operating characteristic curve analysis. Other potential discriminatory markers including Hep Par1 were also evaluated. Forty-six percent (32/69) of hepatocellular carcinoma and all yolk sac tumors revealed at least focal expression of SALL4. A unique punctuate/clumped pattern of nuclear staining was present in 94% (30/32) of hepatocellular carcinoma, whereas all yolk sac tumors displayed a diffuse finely granular nuclear staining pattern. A 25% extent of SALL4 expression cutoff was found to be optimal for the distinction of yolk sac tumor from hepatocellular carcinoma yielding a sensitivity of 100%, specificity of 92.8%, and a positive predictive value of 66.6% for yolk sac tumor diagnosis. The addition of Hep Par1 increased the specificity (99%) and positive predictive value (90%). This is the first report of SALL4 expression in hepatocellular carcinoma. Our finding should be taken into consideration in the differential diagnosis of hepatocellular carcinoma and yolk sac tumor. The unique punctuate/clumped pattern seen in hepatocellular carcinoma cases could be of further discriminatory value.

Glypican-3 expression in gastrointestinal and pancreatic epithelial neoplasms

Glypican-3 (GPC3) is a plasma membrane-bound proteoglycan that can be overexpressed in certain malignancies but has been particularly linked to hepatocellular carcinoma (HCC). GPC3 is currently used as an immunohistochemical marker for HCC, but its expression in epithelial neoplasms of the gastrointestinal (GI) tract and pancreas, a common source of liver metastasis, has not been studied in detail. In this study, we examined GPC3 immunoreactivity in 98 neoplasms of the GI tract including 30 adenocarcinomas (ADCA), 29 squamous cell carcinomas (esophageal and anal), and 39 neuroendocrine carcinomas, and 60 neoplasms of the pancreas including 22 ADCA, 26 pancreatic neuroendocrine neoplasms, and 12 pancreatic acinar cell carcinomas. Two control groups of 32 HCCs and 16 intrahepatic cholangiocarcinomas were also stained with GPC3. Although most (7/12, 58.5%) acinar cell carcinomas were GPC3 positive, pancreatic ADCA and neuroendocrine neoplasms were GPC3 negative. In addition, 27.5%, (8/29) of squamous cell carcinomas, 20% (6/30) of ADCA, and 2.5% (1/39) of neuroendocrine carcinomas of the GI tract were immunoreactive for GPC3. HCC was positive for GPC3 in 75% (24/32) of cases but cholangiocarcinoma was negative. While significant correlation between GPC3 positivity and poor differentiation was observed in HCC only, GPC3 expression did not correlate with tumor size. In conclusion, 14% of GI tract and pancreatic carcinomas/neoplasms (particularly pancreatic acinar cell carcinoma) can express GPC3 by immunohistochemistry. As these tumors commonly metastasize to the liver, this offers a potential pitfall in differentiating between HCC and metastatic carcinoma when evaluating tumors involving the liver.

N-cadherin Expression in Testicular Germ Cell and Gonadal Stromal Tumors

Neural-cadherin is a member of the cadherin gene family encoding the N-cadherin protein that mediates cell adhesion. N-cadherin is a marker of Sertoli cells and is also expressed in germ cells of varying stages of maturation. The purpose of this study was to determine the presence and distribution of this protein by immunohistochemistry in 105 germ cell tumors of both single and mixed histological types and 12 gonadal stromal tumors. Twenty-four germ cell tumors consisted of one cell type and the remaining were mixed. Of the 23 seminomas in either pure or mixed tumors, 74% were positive. Two spermatocytic seminomas were positive. Of the 83 cases with yolk sac tumor, 99% were positive for N-cadherin. The teratomas were positive in 73% in neuroectodermal and / or glandular components. In contrast, 87% of embryonal carcinomas did not express N-cadherin. Only 17% of the syncytiotrophoblastic cells were positive for N-cadherin. In conclusion, N-cadherin expression is very helpful in the identification of yolk sac tumors. In addition to glypican-3 and Sal-like protein 4, N-cadherin can be beneficial for the diagnosis and classification of this subtype of testicular germ cell tumor. Nine of the 12 gonadal stromal tumors were positive to a variable extent.

Immunohistochemical detection of glypican-5 in paraffin-embedded material: an optimized method for a novel research antibody

Glypican-5 (GPC5) is a cell surface heparan sulfate proteoglycan and 1 of 6 closely related members of the glypican family in mammals. Glypicans are predominantly expressed during development in cell-specific and tissue-specific contexts, and the expression of some is linked to developmental disorders and several visceral malignancies. We have previously shown that the region of amplification at 13q31.3 in a subset of rhabdomyosarcomas contains the GPC5 locus, and by copy number and gene expression analyses, that GPC5 is consistently expressed and upregulated in amplified tumors. As the immunohistochemical profile of GPC5 is untested, our aim was to optimize a commercially available anti-human GPC5 antibody for immunohistochemical use in formalin-fixed and paraffin-embedded (FFPE) tissue. Quantitative real-time polymerase chain reaction analyses of normal tissue samples indicated that the brain and testis highly expressed GPC5. High protein expression in these tissues and a cell line constructed to overexpress GPC5 were demonstrated by Western blotting. These normal tissues and the isogenic cell line were FFPE, and immunohistochemical expression of GPC5 was assessed using different methods of antigen retrieval, detection, and primary antibody concentration. The optimum conditions for detection were by heat-induced antigen retrieval, in sodium citrate buffer at pH 6. Enzyme-mediated retrieval did not produce effective detection, producing weaker, less well-localized GPC5 expression. We demonstrate that anti-human GPC5 antibody is amenable to use in FFPE tissue and with the optimized protocol we describe shows specific cellular localization and good staining intensity with minimal background staining.

Difficult differential diagnoses in testicular pathology

CONTEXT

Although relatively rare, testicular cancer is the most common solid organ malignancy in young men and remains a leading cause of cancer death in this population. Different types of testicular tumors are treated differently, with an overall very high cure rate with proper management. Pathologists must, therefore, be familiar with important diagnostic pitfalls in testicular pathology, particularly those that result in different treatments or prognoses.

OBJECTIVE

To summarize key diagnostic features and useful ancillary tools for the most frequently encountered problems in testicular tumor pathology.

DATA SOURCES

Current texts, PubMed (National Library of Medicine) articles, and archives at Indiana University School of Medicine and Beth Israel Deaconess Medical Center were all reviewed.

CONCLUSIONS

Problematic differential diagnoses include seminoma versus nonseminomatous germ cell tumors, germ cell tumors versus non-germ cell tumors, intratubular germ cell neoplasia versus atypical germ cells with maturation arrest, pseudolymphovascular invasion versus real lymphovascular invasion in germ cell tumors, and macroscopic Sertoli cell nodules versus Sertoli cell tumors. In almost all cases, awareness of the differential diagnostic possibilities based on routine light microscopic features permits application of either additional, directed observations or immunohistochemical studies that lead to an accurate diagnosis.

Oral extragonadal yolk sac tumor in a patient with Aicardi syndrome: putative origin and differential diagnosis

We report, for the first time, a primary oral presentation of a germ cell yolk sac tumor in a 4-year-old girl with Aicardi syndrome. The diagnosis, differential diagnosis, and histogenesis are discussed.

Targeting of hepatocellular carcinoma with glypican-3-targeting peptide ligand

Hepatocellular carcinoma is a common malignancy. The carcinoma cells express glypican-3 (GPC-3) on the cell membrane. GPC-3 is also expressed in melanoma cells. Therefore, GPC-3 might be a potential target for tumor imaging or therapy. Here, proteomic mass spectrometry was used to identify peptides that target GPC-3-expressing tumors. A mammalian expression vector expressing a FLAG-GPC-3 fusion protein was cloned for immunoprecipitation. With the use of liposomes, the vector was transfected into HepG2 (HepG2/FLAG-GPC-3) and HEK 293 cells, and the transfected cell lines were selected with geneticin. HepG2/FLAG-GPC-3 cells were used for immunoprecipitation of FLAG-GPC-3 fusion protein. Seven peptide candidates (L1-L7) were selected for GPC-3-targeting ligands by mass spectrometric analysis. The L5 peptide with 14 amino acids (Arg-Leu-Asn-Val-Gly-Gly-Thr-Tyr-Phe-Leu-Thr-Thr-Arg-Gln) showed selective binding to the GPC-3-expressing tumor cells, as did a shortened L5 peptide (L5-2) with seven amino acids (Tyr-Phe-Leu-Thr-Thr-Arg-Gln). These peptide ligands have potential as targeting moieties to GPC-3-expressing tumors for diagnostic and/or therapeutic purposes.

Proteoglycans in cancer biology, tumour microenvironment and angiogenesis

Proteoglycans, key molecular effectors of cell surface and pericellular microenvironments, perform multiple functions in cancer and angiogenesis by virtue of their polyhedric nature and their ability to interact with both ligands and receptors that regulate neoplastic growth and neovascularization. Some proteoglycans such as perlecan, have pro- and anti-angiogenic activities, whereas other proteoglycans, such as syndecans and glypicans, can also directly affect cancer growth by modulating key signalling pathways. The bioactivity of these proteoglycans is further modulated by several classes of enzymes within the tumour microenvironment: (i) sheddases that cleave transmembrane or cell-associated syndecans and glypicans, (ii) various proteinases that cleave the protein core of pericellular proteoglycans and (iii) heparanases and endosulfatases which modify the structure and bioactivity of various heparan sulphate proteoglycans and their bound growth factors. In contrast, some of the small leucine-rich proteoglycans, such as decorin and lumican, act as tumour repressors by physically antagonizing receptor tyrosine kinases including the epidermal growth factor and the Met receptors or integrin receptors thereby evoking anti-survival and pro-apoptotic pathways. In this review we will critically assess the expanding repertoire of molecular interactions attributed to various proteoglycans and will discuss novel proteoglycan functions modulating cancer progression, invasion and metastasis and how these factors regulate the tumour microenvironment.

Induction of latency-associated peptide (transforming growth factor-β(1)) expression on CD4+ T cells reduces Toll-like receptor 4 ligand-induced tumour necrosis factor-α production in a transforming growth factor-β-dependent manner

CD4(+) T cells expressing the latent form of transforming growth factor-β [latency-associated peptide (LAP) (TGF-β(1))] play an important role in the modulation of immune responses. Here, we identified a novel peptide ligand (GPC(81-95) ) with an intrinsic ability to induce membrane-bound LAP (TGF-β(1)) expression on a subpopulation of human CD4(+) T cells (using flow cytometry; ranging from 0·8% to 2·6%) and stimulate peripheral blood mononuclear cells to release LAP (TGF-β(1) ) (using ELISPOT assay; ranging from 0·03% to 0·16%). In spite of this low percentage of responding cells, GPC(81-95) significantly reduced Toll-like receptor 4 ligand-induced tumour necrosis factor-α production in a TGF-β(1) - and CD4(+) T-cell-dependent manner. The results demonstrate that GPC(81-95) is a useful tool to study the functional properties of a subpopulation of LAP (TGF-β(1))(+) CD4(+) T cells and suggest a pathway that can be exploited to suppress inflammatory response.

Glypican 3 has a higher sensitivity than alpha-fetoprotein for testicular and ovarian yolk sac tumour: immunohistochemical investigation with analysis of histological growth patterns

AIMS

Glypican 3 (GPC3) has been reported to be overexpressed in yolk sac tumour (YST), but the sensitivity has not been compared with alpha-fetoprotein (AFP). YST can form numerous growth patterns and the expression of GPC3 in these patterns has not been studied. The aim was to address these aspects.

METHODS AND RESULTS

Sections from testicular or ovarian YST were subjected to immunohistochemistry using GPC3 (n = 39) and AFP (n = 24). Overall immunoreactivity for each case and specific histological patterns were semiquantitatively evaluated (0-3+) and intensity of reactivity was scored (0-3). All cases expressed GPC3 (1+, 5%; 2+, 8%; 3+, 87%) with strong intensity (2.9). The majority expressed AFP (58%) but immunoreactivity was often focal (0, 42%; 1+, 33%; 2+, 25%) and intensity was low (1.0). Using GPC3, >75% of the microcystic (n = 38), macrocystic (n = 26), solid (n = 21), glandular-alveolar (n = 8), endodermal sinus (n = 7), polyvesicular vitelline (n = 5), enteric (n = 4) and micropapillary (n = 2) growth patterns displayed 2+ or 3+ positivity.

CONCLUSIONS

YST can display a variety of growth patterns that can be confused with other germ cell tumour components. GPC3 detects all growth patterns tested and has a higher sensitivity for detecting YST than AFP.

Expression of glypican 3 in placental site trophoblastic tumor

Background

Glypican-3 (GPC3) is a membrane-bound heparan sulfate proteoglycan that functions in embryonic cell growth and differentiation and is highly expressed in the placenta. GPC3 is mutated in Simpson-Golabi-Behmel syndrome, which is characterized by tissue overgrowth and an increased risk of embryonal malignancies. GPC3 has also been implicated in sporadic cancer, particularly hepatocellular carcinoma, for which it has been shown to be a useful diagnostic marker. Although GPC3 expression has been studied in non-neoplastic placental tissue, its presence in gestational trophoblastic diseases has not been previously explored. The purpose of this study was to investigate the immunohistochemical expression of GPC3 in placental site trophoblastic tumor (PSTT), a very rare gestational trophoblastic neoplasm which may be morphologically confused with non-trophoblastic tumors, and to assess its possible utility as a diagnostic marker.

Methods

Fifteen cases of PSTT, as well as samples from placental site nodule (PSN) (n = 2), leiomyosarcoma (n = 1), leiomyoma (n = 1), invasive cervical squamous cell carcinoma (n = 7) and endometrial adenocarcinoma (n = 11) were examined. Immunoreactivity was semi-quantitatively evaluated as negative (0, < 5% of cells stained), focally positive (1+, 5-10% of cells stained), positive (2+, 11-50% of cells stained) or diffusely positive (3+, > 50% of cells stained). Staining intensity for each subtype was graded from 0 to 3 and a mean intensity was calculated.

Results

Eighty percent of PSTT (12/15) were immunoreactive for GPC3 (0, 20; 1+, 20%; 2+, 40%; 3+, 20%) with a mean intensity of 1.3. Stronger, predominately cytoplasmic staining was seen in larger multi- and mononucleated cells with smaller mononucleate cells showing weak muddy cytoplasmic staining. Both PSN cases were positive (1+, 50%; 2+, 50%) and two of nine invasive cervical squamous cell carcinomas showed staining (0, 57%; 1+, 29%; 2+, 14%), predominately in a basal distribution. Other uterine tumors and non-neoplastic tissues were negative.

Conclusions

Identification of GPC3 in PSTT and PSN is consistent with the derivation of these lesions from intermediate trophoblasts, which have been described to express GPC3. GPC3 may be a useful adjunct immunohistochemical marker in differentiating PSTT from non-trophoblastic tumors.

Arginase-1: a new immunohistochemical marker of hepatocytes and hepatocellular neoplasms

The distinction of hepatocellular carcinoma (HCC) from metastatic tumor in the liver often presents a diagnostic challenge that carries significant impact on prognostication and therapy. The number of diagnostically useful immunohistochemical markers of hepatocytes is limited to hepatocyte paraffin antigen (HepPar-1), polyclonal carcinoembryonic antigen, and CD10, with alpha-fetoprotein and glypican-3 labeling HCCs. Arginase-1 (Arg-1) is a binuclear manganese metalloenzyme that catalyzes the hydrolysis of arginine to ornithine and urea. We used immunohistochemistry to compare the sensitivity of Arg-1 to that of HepPar-1 in 151 HCCs. We found that the overall sensitivities of Arg-1 and HepPar-1 are 96.0% and 84.1%, respectively. The sensitivities of Arg-1 in well, moderately, and poorly differentiated HCCs are 100%, 96.2%, and 85.7%, respectively, whereas, in comparison, HepPar-1 demonstrated sensitivities of 100%, 83.0%, and 46.4% for well, moderately, and poorly differentiated tumors, respectively. There were no HCCs in our study that were reactive for HepPar-1 but nonreactive for Arg-1. We also examined Arg-1 expression in nonhepatocellular tumors, including many that are potential mimics of HCC (renal cell carcinomas, neuroendocrine tumors, melanomas, gastric adenocarcinomas, and adrenocortical carcinomas) and found that only 2 non-HCC tumors were reactive for Arg-1. Arg-1 represents a sensitive and specific marker of benign and malignant hepatocytes that may ultimately prove to be a useful diagnostic tool in routine surgical pathology practice.

Intratubular germ cell neoplasia of the testis and its associated cancers: the use of novel biomarkers

Recent advances in the understanding of the molecular pathology of testicular tumours have led to the identification of several new immunohistochemical markers for invasive and in situ germ cell neoplasms. OCT3/4 and NANOG are nuclear stains that have high sensitivity and specificity for the identification of intratubular germ cell neoplasia as well as seminoma and embryonal carcinoma. A potential pitfall in their application to the detection of intratubular germ cell neoplasia, as in other markers that represent oncofetal antigens, is their expression in non-neoplastic germ cells with 'delayed maturation'. SALL4, another nuclear stain, is positive for most germ cell tumours as a group and may be especially helpful in the distinction of these tumours from somatic carcinomas in non-testicular sites. Glypican 3 is a more sensitive marker for yolk sac tumour than alpha-fetoprotein. SOX2 and SOX17 may be useful for differentiating seminoma and embryonal carcinoma, especially following chemotherapy as embryonal carcinoma may lose CD30 expression in this setting. This article reviews the application of these immunohistochemical markers and others to the diagnosis of germ cell neoplasia with reference to older immunohistochemical stains when appropriate. Suggested immunohistochemical panels are described for individual tumour types.

Diagnostic utility of SALL4 in extragonadal yolk sac tumors: an immunohistochemical study of 59 cases with comparison to placental-like alkaline phosphatase, alpha-fetoprotein, and glypican-3

Extragonadal yolk sac tumors (YSTs; primary and metastatic) are rare but are malignant germ cell tumors. Pathologic diagnosis of extragonadal YSTs can be challenging without immunohistochemical markers but markers used for diagnosing these tumors such as placental-like alkaline phosphatase (PLAP), alpha-fetoprotein (AFP), and glypican-3 lack adequate sensitivity and/or specificity. In earlier studies with gonadal germ cell tumors, SALL4 has been identified as a novel diagnostic marker for YSTs and other types of primitive germ cell tumors. Here, we investigated the diagnostic utility of SALL4 in 59 extragonadal YSTs (27 primary sacrococcygeal, 15 primary nonsacrococcygeal, and 17 metastatic) by immunohistochemical staining. We also compared SALL4 with PLAP, AFP, and glypican-3. In addition, we performed immunostains for pancytokeratin, epithelial membrane antigen, and OCT4 in these tumors. Our results showed that all 59 YSTs showed strong pancytokeratin staining (70% tumor cells in 1 case, >90% tumor cells in 58) and 10 (17%) of them also showed focal epithelial membrane antigen staining (<3% tumor cells). All 59 YSTs were negative for OCT4. Strong SALL4 staining was seen in all 59 YSTs (in more than 90% tumor cells in 54 and 70% to 85% tumor cells in 5 YSTs). Only 39 of 59 (66%) YSTs showed positive PLAP staining and the staining was often focal (in less than 30% tumor cells) (28 of 39 cases). Positive AFP staining was seen in the vast majority of YSTs (56 of 59 or 95%); however, 32 (54%) YSTs showed staining in less than 30% tumor cells. Although all 59 YSTs showed positive glypican-3 staining, 18 (30%) showed staining in less than 30% tumor cells, and additional 10 (17%) showed staining in between 30% and 60% tumor cells. In these 59 YSTs, the mean percentage of tumor cells stained with PLAP was 14% (range: 0% to 90%), with AFP 35% (range 0% to 95%), and with glypican-3 57% (range: 1% to 100%), whereas the mean percentage of tumor cells stained for SALL4 was 94% (range: 70% to 100%) (P<0.001). Our results indicate that SALL4 is a novel sensitive (100% sensitivity) diagnostic marker for extragonadal YSTs. SALL4 is a more sensitive marker than PLAP, AFP, or glypican-3 for extragonadal YSTs.

Morphologic, immunohistochemical, and fluorescence in situ hybridization study of ovarian embryonal carcinoma with comparison to solid variant of yolk sac tumor and immature teratoma

The prognosis and therapy for malignant ovarian germ cell tumors including embryonal carcinoma differ from those of other categories of ovarian tumors, making accurate diagnosis imperative for patient care. Because of its rarity, the protein markers and genomic alterations typifying primary ovarian embryonal carcinoma have not been fully characterized. The present study aims to establish a set of sensitive and specific protein markers useful for the diagnosis and delineation of ovarian embryonal carcinoma. Chromosomal 12p anomalies were analyzed by dual-color fluorescence in situ hybridization. In a series of 6 ovarian mixed germ cell tumors with a component of embryonal carcinomas, OCT4, CD30, SOX2, and glypican 3 expressions were analyzed immunohistochemically on formalin-fixed paraffin-embedded tissue specimens. The results were compared to 4 cases of mixed germ cell tumor that were originally mistaken for embryonal carcinoma. OCT4 marked the nuclei of 6 cases, among which 5 cases also showed glypican 3 expression indicative of an admixed yolk sac tumor component. SOX2 was positive in only 3 cases of embryonal carcinoma. In 1 case of mixed germ cell tumor containing embryonal carcinoma, embryoid bodies from a component of polyembryoma were demonstrated to be both OCT4 and CD30 positive. Two cases originally classified as embryonal carcinoma were OCT4 and CD30 negative and showed glypican 3 positivity. They were reclassified as solid variant of yolk sac tumor. Two other cases originally classified as embryonal carcinoma were OCT4 positive and CD30 negative and were classified as immature teratoma with neuroectodermal differentiation based on the immunohistochemical findings as well as morphologic features and were diagnosed as immature teratoma. Chromosome 12p alterations were identified in 5 of 6 cases of embryonal carcinomas. In summary, a panel of immunostains is more useful than a single biomarker in the differential diagnosis of ovarian germ cell tumors. Chromosome 12p fluorescence in situ hybridization combined with OCT4, CD30, and glypican 3 immunostains is useful in confirming the diagnosis of ovarian embryonal carcinoma.

Glypican-3 protein expression in primary and metastatic melanoma: a combined immunohistochemistry and immunocytochemistry study

BACKGROUND

The incidence of melanoma is increasing. Fine-needle aspiration (FNA) is critical in documenting recurrent/metastatic disease in established cases. The potential of metastatic melanoma (MM) to mimic epithelial tumors presents a diagnostic dilemma. In liver FNA, the distinction between hepatocellular carcinoma (HCC) and MM is a frequent challenge. Glypican-3 (GPC3), a heparan sulfate proteoglycan, is a highly sensitive and specific marker for HCC. Serum GPC3 was shown to be expressed in 40% of primary melanomas (PMs), but to the authors' knowledge no tissue studies to date have assessed GPC3 expression in MM. In this study, GPC3 protein expression was investigated in FNAs from MM, and in corresponding histologic sections from the primary tumors.

METHODS

Sixty archival, direct FNA smears or CytoLyt-fixed samples from 50 patients with MM were retrieved together with formalin-fixed, paraffin-embedded specimens available from 17 corresponding PMs. All cases were stained with anti-GPC3 antibody. FNA and core biopsy specimens from HCCs and benign liver were used as positive and negative controls. GPC3 expression was divided into 2 categories: negative (negative or weak cytoplasmic staining) and positive (moderate or strong cytoplasmic with membranous accentuation).

RESULTS

All FNAs from MM cases were negative (0 of 60) for GPC3. The exact 95% Clopper-Pearson confidence interval was 0.0% to 5.96%. Only 1 case of PM (1 of 17; 5.9%) demonstrated weak focal cytoplasmic staining (regarded as negative).

CONCLUSIONS

In the current study, all MM and PM cases in archival FNAs and tissue sections were found to be negative for GPC3. These data suggest that GPC3 is not expressed in melanoma using the 1G12 clone.

Glypican-3 expression in clear cell adenocarcinoma of the ovary

Glypican-3 is a heparan sulfate proteoglycan that is overexpressed in various neoplasms such as hepatocellular carcinoma, malignant melanoma, and testicular yolk sac tumor. Glypican-3 is currently regarded as a tumor marker and potential target for immunotherapy. To clarify the significance of glypican-3 expression in ovarian clear cell adenocarcinoma, we evaluated glypican-3 expression by immunohistochemistry in nonneoplastic and neoplastic ovaries, and other Müllerian duct derivatives including endometrium in different menstrual phases. Among the benign lesions examined, glypican-3 expression was identified exclusively in the endometrial epithelium in the gestational period. A total of 213 cases of ovarian adenocarcinoma, including 94 clear cell adenocarcinomas, were studied. Glypican-3 expression was observed in 44% of clear cell adenocarcinomas, whereas it was rarely observed in other histological subtypes: mucinous (4%), endometrioid (5%), and serous (11%; P<0.0001). All six ovarian yolk sac tumors showed diffuse immunoreactivity for glypican-3. In cases of clear cell adenocarcinoma, no correlations were found between glypican-3 expression and clinicopathological factors, such as tumor stage, lymph node metastasis, peritoneal dissemination, and death rate. However, glypican-3 expression was significantly associated with poor overall survival in stage III/IV clear cell adenocarcinoma cases. Our results suggest that overexpression of glypican-3 may be related to the development and aggressive behavior of ovarian clear cell adenocarcinoma.

Glypican 3-expressing gastric carcinoma: distinct subgroup unifying hepatoid, clear-cell, and alpha-fetoprotein-producing gastric carcinomas

Gypican-3 (GPC3) has been recognized as an oncofetal protein in hepatic neoplasms and yolk sac tumors. To characterize a distinct subgroup of gastric carcinoma (GC) expressing GPC3 (GPC3-GC), primary and metastatic GC tissues were evaluated by immunohistochemistry with special focus on their related entities: hepatoid, clear-cell, and alpha-fetoprotein-producing GC. GPC3-GC was defined as focal GPC3-GC when 10-49% of neoplastic cells were positive, and as diffuse GPC3-GC when more than 50% of cells were positive. Among 926 GC cases, 101 (11%) were GPC3-GC, of which 45 were diffuse and 56 were focal GPC3-GC. Specific histological patterns, such as the hepatoid and clear-cell patterns, were frequently observed in diffuse GPC3-GC (38 and 49%, respectively) and in focal GPC3-GC (4 and 25%, respectively), whereas these patterns were extremely rare in GPC3-negative GC. Immunoreactive alpha-fetoprotein was only identified in GPC3-GC (38% of diffuse and 14% of focal GPC3-GC). Both diffuse and focal GPC3-GC showed nodal metastasis more frequently (67 and 55%, respectively) than GPC3-negative GC (34%), and the diffuse GPC3-GC had significantly more T2-4 and M1 stage cases. GPC3 immunostaining was present in 57 out of 61 nodal metastases (93%) and in all four liver metastases examined. Importantly, diffuse GPC3 expression was observed in the liver metastasis, even if the primary tumor was focal GPC3-GC. GPC3-GC is a distinctive group of GC, which unifies hepatoid, clear-cell, and alpha-fetoprotein-producing GC. GPC3 is expected to be a target of forthcoming immunotherapy for a patient bearing this specific type of GC.