Overexpression of SerpinB9 in non-seminomatous germ cell tumors

Serpinb9 is an inhibitor of granzyme B and is potentially involved in the immune escape of tumor cells. In the present study, bioinformatics analysis using open databases suggested that SerpinB9 is overexpressed in testicular embryonal carcinoma. Immunohistological analysis was performed on 28 cases of testicular germ cell tumors to investigate the relationship between SerpinB9 expression in testicular germ cell tumors and the tumor immune environment. SerpinB9 was significantly upregulated in the non-seminoma group and inversely correlated with the number of tumor-infiltrating CD8-positive cells. In addition, yolk sac tumors were characterized by the loss of human leukocyte antigen-class I expression. These findings suggest that SerpinB9 contributes to the immune escape of testicular germ cell tumors. Targeting therapy for SerpinB9 might therefore be useful in immunotherapy for testicular germ cell tumors resistant to immune checkpoint inhibitors.

Overexpression of melanoma-associated antigen A2 has a clinical significance in embryonal carcinoma and is associated with tumor progression

INTRODUCTION

Melanoma-associated antigen A2 (MAGE-A2) is a member of the cancer-testis antigen family differentially overexpressed in a variety of malignancies and is associated with tumor development. However, clinical significance and prognostic value of MAGE-A2 in different histological subtypes of testicular germ cell tumors (TGCTs) have not been explored.

MATERIALS AND METHODS

Here, we aimed to investigate the clinical significance and prognostic impact of MAGE-A2 expression in TGCTs compared to benign tumors as well as adjacent normal tissues and then between seminomas and non-seminomas groups using immunohistochemistry on tissue microarrays.

RESULTS

The results indicated a statistically significant difference between overexpression of MAGE-A2 and histological subtypes of TGCTs. A statistically significant association was found between a high level of nuclear expression of MAGE-A2 protein and advanced pT stage (P = 0.022), vascular invasion (P = 0.037), as well as involvement of rete testis (P = 0.022) in embryonal carcinomas. Increased nuclear expression of MAGE-A2 was observed to be associated with more aggressive behaviors and tumor progression rather than cytoplasmic expression in these cases. Further, high level nuclear expression of MAGE-A2 had shorter disease-specific survival (DSS) or progression-free survival (PFS) compared to patients with moderate and low expression of MAGE-A2, however, without a statistically significant association.

CONCLUSION

Our results confirm that increased nuclear expression of MAGE-A2 has a clinical significance in embryonal carcinomas and is associated with progression of disease. Moreover, MAGE-A2 may act as a potential predictive biomarker for the prognosis in embryonal carcinomas if follow-up period becomes longer. Further investigations for the biological function of MAGE-A2 are required in future studies.

Fermented Ginseng Extract, BST204, Suppresses Tumorigenesis and Migration of Embryonic Carcinoma through Inhibition of Cancer Stem Cell Properties

The pharmacological effects of BST204—a fermented ginseng extract—on several types of cancers have been reported. However, the effects of ginseng products or single ginsenosides against cancer stem cells are still poorly understood. In this study, we identified the anti-tumorigenic and anti-invasive activities of BST204 through the suppression of the cancer stem cell marker, CD133. The treatment of embryonic carcinoma cells with BST204 induced the expression of the tumor suppressor protein, p53, which decreased the expression of cell cycle regulatory proteins and downregulated the expression of CD133 and several stemness transcription factors. These changes resulted in both the inhibition of tumor cell proliferation and tumorigenesis. The knockdown of CD133 suggests that it has a role in tumorigenesis, but not in cancer cell proliferation or cell cycle arrest. Treatment with BST204 resulted in the reduced expression of the mesenchymal marker, N-cadherin, and the increased expression of the epithelial marker, E-cadherin, leading to the suppression of tumor cell migration and invasion. The knockdown of CD133 also exhibited an anti-invasive effect, indicating the role of CD133 in tumor invasion. The single ginsenosides Rg3 and Rh2—major components of BST204—exhibited limited effects against cancer stem cells compared to BST204, suggesting possible synergism among several ginsenoside compounds.

SC1 inhibits the differentiation of F9 embryonic carcinoma cells induced by retinoic acid

The ability to self-renew is one of the most important properties of embryonic stem (ES) cells. Pluripotin (SC1), a small molecule with high activity and low toxicity, promotes self-renewal in mouse ES cells. SC1 can noticeably change the morphology of retinoic acid (RA)-induced F9 embryonic carcinoma cells (F9 cells). However, in the long term, RA and SC1 together cause cell apoptosis. When being added after 18-24 h of RA-induced F9 cell differentiation, SC1 transitorily activated Nanog and Oct4. Both Nanog and Oct4 were downregulated when SC1 and RA were added simultaneously. On the other hand, Klf4 was continually activated when SC1 was added between 6 and 24 h. Phosphorylated Erk1/2 protein levels were reduced from 6 to 24 h, whereas unphosphorylated Erk1 protein levels remained unchanged. A higher concentration of SC1 promoted cell self-renewal by strengthening the inhibition of Erk1/2 protein phosphorylation in F9 cells. Furthermore, SC1 and RA affect global DNA methylation by influencing the expressions of methylation-associated proteins, including Dnmt3b, Dnmt3l, Tet1, Tet2, and Tet3. In conclusion, SC1 inhibits the differentiation of RA-induced F9 cells mainly by reducing the levels of phosphorylated Erk1/2 and enhancing the expression of Klf4, although it also reduces DNA methylation, which may have an additional effect on ES cell differentiation.

PECULIARITIES OF CATENIN ACTIVITY IN THE EMBRYONAL TESTICULAR CARCINOMA

The aim of the research was to study immunohistochemical peculiarities of catenin activity in the embryonal testicular carcinoma. Material is presented by 39 cases of embryonal testicular carcinoma for the period from 1993 to 2013. Macroscopic and histological investigation has been performed according to the WHO classification (2004). Immunohistochemical examination with monoclonal antibodies to Ki-67, β-catenin and E-cadherin were performed. Embryonal carcinoma is presented 12.38% of all testicular germ cell tumors in our observations with median age of patients 30.85±1.16 years. Embryonic cancer of testis has been characterized histologicaly with combination of different areas of the structure: solid, forming a diffuse field, and acinar, tubular and papillary structures with different developed connective tissue background. Tumor cells are characterized by well-defined cytoplasm, polymorphic hyperchromatic nuclei with distinct nucleoli. Embryonic cancer is characterized pronounced reducing of membranous β-catenin expression (that is usual localization of that protein) with uneven level of expression from weak till strong. Simultaneously nuclear positive immunoreactivity has been appeared in embryonic cancer in isolate and grouped cells of tumor. Correlation between Ki-67 and β-catenin expression is 0.562, between E-cadherin and β-catenin is 0.737. It was concluded that immunohistochemical catenin activity must be interpreted accurately in case of embryonal carcinoma of the testis as there is no clear evidence on prognostic importance of neoplastic behavior as it is in some other tumors.

[Diagnostic value of immunohistochemistry and FISH for chromosome 12p in type Ⅱ testicular germ cell tumors]

OBJECTIVE

To study the pathological morphology, immunohistochemical characteristics, and molecular changes of type Ⅱ testicular germ cell tumors (TGCT) and investigate the possible value of immunohistochemistry and fluorescence in situ hybridization (FISH) in the diagnosis of TGCT.

METHODS

We collected for this study 97 cases of TGCT, including 75 cases of seminoma, 17 cases of embryonal carcinoma, 11 cases of yolk sac tumor, 16 cases of mature teratoma, 3 cases of immature teratoma, and 1 case of epidermoid cyst, in which normal testicular tissue was found in 20 and non-TGCT in 6. We detected the expressions of different antibodies in various subtypes of TGCT by immunohistochemistry and determined the rate of chromosome 12p abnormality using FISH.

RESULTS

The immunophenotypes varied with different subtypes of TGCT. SALL4 and PLAP exhibited high sensitivity in all histological subtypes. CD117 and OCT4 showed strongly positive expressions in invasive seminoma and germ cell neoplasia in situ (GCNIS) but not in normal seminiferous tubules. GPC3 was significantly expressed in the yolk sac tumor, superior to GATA3 and AFP in both range and intensity. CKpan, OCT4, and CD30 were extensively expressed in embryonal carcinoma, while HCG expressed in choriocarcinoma. The positivity rate of isochromosome 12p and 12p amplification in TGCT was 96.7% (29/30).

CONCLUSIONS

The majority of TGCT can be diagnosed by histological observation, but immunohistochemical staining is crucial for more accurate subtypes and valuable for selection of individualized treatment options and evaluation of prognosis. Chromosome 12p abnormality is a specific molecular alteration in type Ⅱ TGCT, which is useful for ruling out other lesions.

Downregulation of miR-320a/383-sponge-like long non-coding RNA NLC1-C (narcolepsy candidate-region 1 genes) is associated with male infertility and promotes testicular embryonal carcinoma cell proliferation

Long non-coding RNAs (lncRNAs), which are extensively transcribed from the genome, have been proposed to be key regulators of diverse biological processes. However, little is known about the role of lncRNAs in regulating spermatogenesis in human males. Here, using microarray technology, we show altered expression of lncRNAs in the testes of infertile men with maturation arrest (MA) or hypospermatogenesis (Hypo), with 757 and 2370 differentially down-regulated and 475 and 163 up-regulated lncRNAs in MA and Hypo, respectively. These findings were confirmed by quantitative real-time PCR (qRT-PCR) assays on select lncRNAs, including HOTTIP, imsrna320, imsrna292 and NLC1-C (narcolepsy candidate-region 1 genes). Interestingly, NLC1-C, also known as long intergenic non-protein-coding RNA162 (LINC00162), was down-regulated in the cytoplasm and accumulated in the nucleus of spermatogonia and primary spermatocytes in the testes of infertile men with mixed patterns of MA compared with normal control. The accumulation of NLC1-C in the nucleus repressed miR-320a and miR-383 transcript and promoted testicular embryonal carcinoma cell proliferation by binding to Nucleolin. Here, we define a novel mechanism by which lncRNAs modulate miRNA expression at the transcriptional level by binding to RNA-binding proteins to regulate human spermatogenesis.

Molecular profiling of embryonal carcinoma cells following retinoic acid or histone deacetylase inhibitor treatment

Regulation of tissue homeostasis is crucial to disease prevention; cell division, cell cycle arrest, differentiation and apoptosis have to be tightly controlled in order to maintain this homeostasis. Retinoic acid (RA) and the histone deacetylase inhibitors (HDACIs) have profound effects on these processes and thus may be critical regulators of homeostasis. Consequently, RA and/or histone deacetylase inhibitors are currently being tested in clinical trials for a variety of cancers. Unfortunately, little is known of the overall affect of these compounds on cellular gene expression. Therefore, we decided to compare the effects of all-trans retinoic acid (ATRA) and a particular HDACI-Trichostatin A (TSA)-on an embryonal carcinoma (EC) cell line (F9) using gene chip analysis. We have focused particular attention on those genes that may be differentially affected by these compounds. Within the parameters established for this study, only 116 of the 12,488 genes examined were similarly regulated by ATRA and TSA: 75 positively and 41 negatively. An additional 70 genes were affected by only one of the compounds and 19 genes were actually inversely regulated. The gene set inversely regulated by ATRA and TSA includes several important patterning genes as well as the crucial tumor suppressor/promoter, transforming growth factor beta 1 (TGFbeta1). Promoter analysis suggests a motif that may regulate one set of these genes. This study provides the first comprehensive comparison of global gene expression on EC cells as affected by ATRA and a HDAC inhibitor (TSA); reveals new targets for ATRA and HDAC inhibitors; identifies a new regulatory motif; demonstrates that ATRA and HDAC inhibitors do not always act synergistically on gene expression; and examines particular questions regarding their concurrent clinical application.

Role of SOX2 in the etiology of embryonal carcinoma, based on analysis of the NCCIT and NT2 cell lines

The transcription factor SOX2, associated with amongst others OCT3/4, is essential for maintenance of pluripotency and self-renewal of embryonic stem cells. SOX2 is highly expressed in embryonal carcinoma (EC), the stem cell component of malignant nonseminomatous germ cell tumors, referred to as germ cell cancer (GCC). In fact, OCT3/4 together with SOX2 is an informative diagnostic tool for EC in a clinical setting. Several studies support the hypothesis that SOX2 is a relevant oncogenic factor in various cancers and recently, SOX2 has been suggested as a putative therapeutic target for early stage EC. We demonstrate the presence of genomic amplification of SOX2 in an EC cell line, NCCIT, using array comparative genome hybridization and fluorescence in situ hybridization. Down-regulation of SOX2 by targeted siRNA provokes NCCIT cells towards apoptosis, while inhibition of OCT3/4 expression induced differentiation, with retained SOX2 levels. Mice pluripotent xenografts from NCCIT (N-NCCIT and N2-NCCIT) show a consistent SOX2 expression, in spite of loss of the expression of OCT3/4, and differentiation, with retained presence of genomic amplification. No SOX2 amplification has been identified in primary pure and mixed EC in vivo patient samples so far. The data presented in this study are based on a single EC cell line with a SOX2 amplification, with NT2 as control EC cell line, showing no profound induction of apoptosis upon SOX2 downregulation. The findings are of relevance to identify mechanisms involved in the pathogenesis of EC tumors, and support the model of SOX2-oncogene dependency of EC, which however, does not exclude induction of differentiation. This finding is likely related to the presence of wild type p53 in GCC, resulting in expression of downstream target genes, amongst others miR-34a, miR-145 and SOX2, associated to the unique sensitivity of GCC to DNA damaging agents.

Persistent CD30 expression by embryonal carcinoma in the treatment time course: prognostic significance of a worthwhile target for personalized treatment

PURPOSE

CD30 is expressed by untreated embryonal carcinoma, supporting the rationale for a targeted approach. However, the reported chemotherapy induced switching off of CD30 noted on immunohistochemistry may affect its therapeutic potential for disease relapse. We evaluated persistent CD30 expression and its prognostic meaning in cases of post-chemotherapy residual disease.

MATERIALS AND METHODS

Paraffin blocks of surgical samples that yielded nonteratomatous viable cells after 1 or more cisplatin based chemotherapy treatments were retrieved and reassessed by 2 pathologists blinded to the study purpose. Multivariable analysis was done for prespecified factors.

RESULTS

A total of 49 cases of pure embryonal carcinoma or mixed germ cell tumor from August 1991 to August 2012 had full clinical data and suitable tissue available for analysis. Of the 35 cases (71.4%, 95% CI 56.7-83.4) with preserved CD30 positivity 14 (40.0%) showed residual disease after a median of 1 regimen (IQR 1-2). Five-year overall survival in CD30 positive and negative cases was 37.0% (95% CI 22.1-61.8) and 50.1% (95% CI 27.9-90.0, p=0.078), while after first line treatment it was 23.2% (95% CI 8.6-62.5) and 47.6% (95% CI 18.8-100, p=0.025), respectively. On multivariable analysis CD30 positivity was a significant prognostic factor for progression-free survival (HR 2.32, 95% CI 1.04-5.19) and overall survival (HR 2.77, 95% CI 1.05-7.29).

CONCLUSIONS

CD30 was retained even after an intensive pretreatment load, confirming that it is a reliable treatment target. Its expression was associated with a significantly poorer prognosis in multiple relapse/chemoresistant cases and it was an independent prognostic factor for survival.

Transforming pluripotency: an exon-level study of malignancy-specific transcripts in human embryonal carcinoma and embryonic stem cells

To circumvent difficulties of isolating pure populations of cancer stem cells (CSCs) for the purpose of identifying malignancy-specific gene expression, we have compared exon-resolution transcriptomic profiles of 5 embryonal carcinoma (EC) cell lines, a histological subtype of germ cell tumor (GCT), to their nonmalignant caricature, specifically 6 human embryonic stem (ES) cell lines. Both cell types are readily accessible, and were purified for undifferentiated cells only. We identified a set of 28 differentially expressed genes, many of which had cancer and stemness roles. Overexpression of the recently discovered pluripotency gene NR5A2 in malignant EC cells revealed an intriguing indication of how WNT-mediated dysregulation of pluripotency is involved with malignancy. Expression of these 28 genes was further explored within 2 publically available data sets of primary EC tumors and normal testis. At the exon-level, alternative splicing events were detected in ZNF195, DNMT3B, and PMF1, and alternative promoters were detected for ASH2L and ETV5. These events were validated by reverse transcriptase-polymerase chain reaction-based methods in EC and ES lines, where the alternative splicing event in the de novo DNA methyltransferase DNMT3B may have functional consequences. In conclusion, we have identified malignancy-specific gene expression differences within a rigorous pluripotent stem cell context. These findings are of particular interest for both GCT and ES cell biology, and, in general, to the concept of CSCs.

Sodium/iodide symporter is expressed in the majority of seminomas and embryonal testicular carcinomas

Testicular cancer is the most frequent cancer in young men. The large majority of patients have a good prognosis, but in a small group of tumors, the current treatments are not effective. Radioiodine is routinely used in the treatment of thyroid cancer and is currently investigated as a potential therapeutic tool even for extra-thyroid tumors able to concentrate this radioisotope. Expression of Na(+)/I(-) symporter (NIS (SLC5A5)), the glycoprotein responsible for iodide transport, has been demonstrated in normal testicular tissue. In this study, we analyzed NIS expression in a large series of testicular carcinomas. Our retrospective series included 107 patients operated for testicular tumors: 98 typical seminomas, six embryonal carcinomas, one mixed embryonal choriocarcinoma, and two Leydig cells tumors. Expression and regulation of NIS mRNA and protein levels were also investigated in human embryonal testicular carcinoma cells (NTERA) by real-time RT-PCR and western blotting respectively. Immunohistochemical analysis showed the presence of NIS in the large majority of seminomas (90/98) and embryonal carcinomas (5/7) of the testis but not in Leydig cell carcinomas. Expression of NIS protein was significantly associated with lymphovascular invasion. In NTERA cells treated with the histone deacetylase inhibitors SAHA and valproic acid, a significant increase in NIS mRNA (about 60- and 30-fold vs control, P<0.001 and P<0.01 respectively) and protein levels, resulting in enhanced ability to uptake radioiodine, was observed. Finally, NIS expression in testicular tumors with the more aggressive behavior is of interest for the potential use of targeting NIS to deliver radioiodine in malignant cells.

Involvement of the cAMP response element binding protein, CREB, and cyclin D1 in LPA-induced proliferation of P19 embryonic carcinoma cells

Lysophosphatidic acid (LPA) is a lipid growth factor that induces proliferation of fibroblasts by activating the cAMP response element binding protein (CREB). Here, we further investigated whether LPA induces proliferation of P19 cells, a line of pluripotent embryonic carcinoma cells. 5'-Bromo-2-deoxyuridine incorporation and cell viability assays showed that LPA stimulated proliferation of P19 cells. Immunoblot experiments with P19 cells revealed that the mitogen activated protein kinases, including p-ERK, p38, pAKT, glycogen synthase kinase 3β, and CREB were phosphorylated by treatment with 10 μM LPA. LPA-induced phosphorylation of CREB was efficiently blocked by U0126 and H89, inhibitors of the MAP kinases ERK1/2 and mitogen- and stress-activated protein kinase 1, respectively. Involvement of cyclin D1 in LPA-induced P19 cell proliferation was verified by immunoblot analysis in combination with pharmacological inhibitor treatment. Furthermore, LPA up-regulated CRE-harboring cyclin D1 promoter activity, suggesting that CREB and cyclin D1 play significant roles in LPA-induced proliferation of P19 embryonic carcinoma cells.

Morphologic features of human chorionic gonadotropin- or alpha-fetoprotein-producing germ cell tumors of the central nervous system: histological heterogeneity and surgical meaning

Our study of germ cell tumors (GCT) of the central nervous system (CNS) investigated the relationship between tumor histology and patient serum titers of human chorionic gonadotropin (HGC) and alpha-fetoprotein (AFP). Thirty-five patients were enrolled. Their serum titers of HCG (mlU/ml) and/or AFP (ng/ml) before initial treatment were available, as were tumor specimens obtained before the administration of adjuvant therapy. They were divided into three groups, depending on whether HCG alone (group H), AFP alone (group A), or both HCG and AFP (group HA) were detected. Each group was subdivided into three groups: patients in group I had H, A, and/or HA titers below 9.9; patients in group II/III had titers from 10.0 to 999; and those in group IV had titers of 1000 or more. Serial sections of tissue specimens were repeatedly stained, mainly with hematoxylin and eosin (H-E) stain, HCG immunostain, and AFP immunostain. There were seven patients in the H-I group and five in H-II/III. Of these 12 patients, 11 had germinomas (G) and one had an embryonal carcinoma (EC). Five patients were included in group A: one was classified as A-II/III and had a germinoma, and the remaining four patients were in A-IV and had yolk sac tumors (YST) or mixed GCT consisting mainly of YST or EC (MXGCT-YST, EC). The HA group consisted of 18 patients. Three were classified as HA-I and had germinomas; nine HA-II/III patients had T or MXGCT-T; and six HA-IV patients had choriocarcinoma (CC), YST, MXGCT-CC, or MXGCT-YST. Throughout the study, the situations for the elevated serum titers could be elucidated in only four cases (three in group A-IV and one in group HA-IV). These results led to the conclusion that serologic evaluation is superior to morphologic evaluation in diagnosing marker-producing GCTs. From a diagnostic perspective, the role of surgery is to verify the HCG- and AFP-immunonegative tissue in patients with G, T, and EC.

Differential Akt signalling in non-seminomatous testicular germ cell tumors

AIM

To investigate the protein kinase B (Akt) signalling proteins phosphatase and tensin homolog (PTEN), phosphorylated-Akt (p-Akt) and cyclin-dependent kinase inhibitor 1B (p27(Kip1)) in non-seminomatous germ cell tumors (NST) with a view to future investigative approaches.

MATERIALS AND METHODS

The expressions of PTEN, p-Akt and p27(Kip1) were immunohistochemically assessed in 17 teratomas, 27 embryonal cell carcinomas, 6 yolk sac tumors and 24 benign testicular parenchymas. The cytoplasmic and corresponding nuclear expressions were compared and correlated to tumor entity.

RESULTS

PTEN was dramatically reduced in all the NST subgroups. Concentrated nuclear p27(Kip1) and loss of the cytoplasmic form was found in teratomas and embryonal cell carcinomas. Neither altered expression nor negative Akt regulation was found. The yolk sac tumors showed late cytoplasmic shift of PTEN and p27(Kip1).

CONCLUSION

Both, the absence of overexpression of p-Akt and of negative correlations to PTEN and p27(Kip1) suggest that signalling of these parameters in NST might include additional mechanisms such as crosstalk to other pathways rather than classical Akt activation.

Identification of the estrogen receptor GPER in neoplastic and non-neoplastic human testes

BACKGROUND

Estrogen signaling is mediated by estrogen receptor beta isoforms in normal and neoplastic human testes. Recently, a G-protein-coupled-receptor (GPER) has been suggested as being involved in rapid responses to estrogens in different normal and tumor cells.

METHODS

This study investigated the GPER expression in paraffin-embedded samples from non neoplastic and neoplastic human testes (sex-cord stromal and germ cell tumors) by immunohistochemical and Western Blot analyses.

RESULTS

In control testes, a positive GPER immunoreactivity was detected in Leydig and in Sertoli cells while all germ cells were immunonegative. Furthermore, neoplastic cells of the Sertoli cell tumor, Leydig cell tumor, seminoma and embryonal carcinoma samples were all immunopositive. The immunoblots of testis extracts confirmed the results.

CONCLUSIONS

These findings suggest that GPER could mediate estrogen signaling in both normal and transformed somatic cells of human testis, but they reveal a differential expression of the novel estrogen receptor in non neoplastic and neoplastic germ cells.

Antiproliferation and redifferentiation in thyroid cancer cell lines by polyphenol phytochemicals

Thyroid carcinogenesis is accompanied by loss of thyroid-specific functions and refractory to radioiodine and thyroid stimulating hormone (TSH) suppression therapy. Redifferentiating agents have been shown to inhibit tumor growth and improve the response to conventional therapy. Polyphenol phytochemicals (PPs) in fruits and vegetables have been reported to inhibit cancer initiation, promotion, progression and induce redifferentiation in selected types. In this study we examined PPs induce redifferentiation in thyroid cancer cell lines. We investigated the effects of genistein, resveratrol, quercetin, kaempferol, and resorcinol on the F9 embryonal carcinoma cell differentiation model. The thyroid cancer cell lines, TPC-1, FTC-133, NPA, FRO, and ARO, displayed growth inhibition in response to genistein, resveratrol, quercetin. We further demonstrated that genistein decreased the dedifferention marker CD97 in NPA cells and resveratrol decreased CD97 in FTC-133, NPA, FRO cells and quercetin decreased CD97 in all cell lines. We observed increased expression of differentiation marker NIS in FTC-133 cells in response to genistein, and resveratrol but no change in NPA, FRO, ARO cells. Quercetin increased or induced NIS in FTC-133, NPA, FRO cells. These findings suggest that PPs may provide a useful therapeutic intervention in thyroid cancer redifferentiation therapy.

Temporal expression profiling of the effects of secreted factors from prostate stromal cells on embryonal carcinoma stem cells

BACKGROUND

There is a growing body of evidence indicating that epigenetic influences originating from stromal cells in the immediate microenvironment may play a role in carcinogenesis. Determining the molecular mechanisms involved in stromal-stem cell interaction could provide critical insight into prostate development and disease progression, particularly with regard to their relationship to and influence on the putative cancer stem cell.

METHODS

Prostate and bladder stromal cells prepared from tissue specimens were co-cultured with the pluripotent embryonal carcinoma cell line NCCIT. Transcriptome analysis was used to characterize NCCIT cell response to prostate or bladder signaling.

RESULTS

A systems approach demonstrated that prostate stromal cells were capable of inducing gene expression changes in NCCIT through secreted factors. Induction led to a loss of embryonic stem cell markers, with concurrent up-regulation of many genes characteristic of stromal mesenchyme cells as well as some of epithelial and cancer stem cells. Bladder stromal signaling produced gene expression changes different from those of prostate signaling.

CONCLUSIONS

This study indicates that paracrine stromal cell signaling can affect cancer stem cell response in an organ-specific manner and may provide insight for future development of treatment strategies such as differentiation therapy.

[Identification of human testicular embryonal carcinoma proteins by two-dimensional gel electrophoresis and mass spectrometry]

OBJECTIVE

To separate and identify human testicular embryonal carcinoma proteomics using two-dimensional electrophoresis (2-DE) and mass spectrometry.

METHODS

Immobilized pH gradient two-dimensional polyacrylamide gel electrophoresis was used to separate the total proteins of the samples. After silver staining, PDQuest 7.30 image analysis software was applied to analyze the 2-DE images. Three of the proteins highly expressed in human testicular embryonal carcinoma were identified by matrix-assisted laser adsorption/ionization-time of flight-tandem mass spectrometry (MALDI-TOF-MS/MS).

RESULTS

2-DE effectively screened the differentially expressed proteins in the carcinoma tissues. Three proteins highly expressed in the carcinoma were successfully identified.

CONCLUSION

The proteins of human testicular embryonal carcinoma can be effectively separated and analyzed using 2-DE and mass spectrometry. Proteomic analysis offers a new means for further study of this carcinoma.

Identification of ERbeta1 and ERbeta2 in human seminoma, in embryonal carcinoma and in their adjacent intratubular germ cell neoplasia

BACKGROUND

Estrogens exert a role on germ cell physiology of normal human testis through the mediation of the estrogen receptor (ER) beta subtypes. Epidemiological studies evidenced an increased incidence of testicular germ cell cancer after elevated pre-natal estrogen exposure but the expression of estrogen receptors in these testicular neoplasms has not been well elucidated.

METHODS

Immunohistochemistry and Western blot analysis were used to investigate the expression of three distinct ER isoforms, ERalpha, ERbeta1, and ERbeta2 in paraffin-embedded tissues from seminomas and embryonal carcinomas, which are the most common testicular germ cell tumours.

RESULTS

Neoplastic cells of all specimens revealed a positive ERbeta1 and ERbeta2 immunoreactivity, while the ERalpha signal was undetectable. A similar pattern of estrogen receptor immunostaining was also observed in the malignant germ cells of intratubular germ cell neoplasia, adjacent to testicular cancers. Western blot analysis of tumour extracts revealed two immunoreactive bands, a 59 kDa band for ERbeta1 and a 53 kDa band for ERbeta2.

CONCLUSION

A variable ERbeta expression was previously reported in testicular germ cell tumours and, particularly, an ERbeta down-regulation was evidenced in seminoma and embryonal carcinoma. Conversely, the current study has clearly identified ERbeta1 and ERbeta2 in the neoplastic cells of seminoma and embryonal carcinoma, as well as in the malignant cells of their common pre-invasive precursor, intratubular germ cell neoplasia. Therefore, our findings suggest that ERbeta1, together with a possible ERbeta2 contribute, can mediate estrogen action in both early and late neoplastic testicular germ cells, not confirming the previously hypothesized antiproliferative effect of ERbeta on male gonadal cells.

Cell-cell signaling through NOTCH regulates human embryonic stem cell proliferation

Unlike pluripotent mouse embryonic stem (ES) cells, human ES cells and their malignant equivalents, embryonal carcinoma (EC) cells, require close cell-cell contact for efficient growth. Signaling through the NOTCH receptor, initiated by interaction with ligands of the DELTA/JAGGED family expressed on neighboring cells, plays a role in regulating the self-renewal of several stem cell systems. Members of the NOTCH and DELTA/JAGGED families are expressed by human EC and ES cells, and we have therefore investigated the possible role of NOTCH in the maintenance of these cells. Cleavage of both NOTCH1 and NOTCH2 to yield the intracellular domain responsible for the canonical signaling pathway of NOTCH was detected in several human EC and ES cell lines, suggesting that NOTCH signaling is active. Furthermore, the proliferation of human EC cells, as well as the expression of several downstream NOTCH target genes, was markedly reduced after small interfering RNA knockdown of NOTCH1, NOTCH2, and the canonical effector CBF-1 or after blocking NOTCH signaling with the gamma-secretase inhibitor L-685,458. The inhibitor also caused a reduction in the growth of human ES cells, although without evidence of differentiation. The results indicate that cell-cell signaling through the NOTCH system provides a critical cue for the proliferation of human EC and ES cell in vitro.

Genome-wide expression profiling reveals new insights into pathogenesis and progression of testicular germ cell tumors

Testicular germ cell tumors (GCT) are the most frequent malignancy in young adults and arise from intratubular germ cell neoplasia undetermined (IGCNU, also referred to as carcinoma in situ, CIS). To determine the transcriptional programs involved in the transition from normal germ cells to GCT, and to further elucidate genetic differences between seminomas and non-seminomatous GCT the global expression profile of 12 neoplastic and 3 normal testicular tissues were investigated by whole genome cDNA microarrays. Transcriptional differences between seminomas and embryonal carcinomas were determined and gene signatures characterizing histological subtypes of GCT were identified. The most significant difference between seminomas and embryonal carcinomas was the expression of spermatogenesis-associated genes (PRAME, MAGEA4, SPAG1, HPX) in seminomas and regulatory genes DNMT3B and SOX2 as well as small molecular weight keratins KRT8, KRT18 in embryonal carcinomas. The expression of several selected genes (CK18, MAGE-A4, SOX2, DNMT3B, CD30, KIT) was studied by immunohistochemistry or reverse transcriptase-polymerase chain reaction (RT-PCR) in a large collective of GCT. In summary, our data identified tumor type-specific gene signatures of GCT and provided new insights into genetic pathways driving the transition to seminomas and embryonal carcinomas from their respective precursor lesions.

Successful co-immunoprecipitation of Oct4 and Nanog using cross-linking

The transcription factors Oct4 and Nanog are essential for the maintenance of an undifferentiated and pluripotent state in early embryonic cells, embryonic stem cells and embryonal carcinoma cells in humans and mice. These factors are co-localized to promoters of more than 300 genes, and synergistically regulate their activities. Currently, the molecular interaction between these two factors has not been well-characterized. During attempts to co-immunoprecipitate Oct4 and Nanog we found that cross-linking with dithiobis[succinimidylpropionate] was necessary to maintain their interaction. This result was supported by gel filtration analysis. Surprisingly, formaldehyde, a cross-linker commonly used during chromatin immunoprecipitation of Oct4 and Nanog, did not preserve the complex. Our findings demonstrate the effectiveness of using DSP to mitigate the instability of the interaction between these two particular proteins. Additionally, this solution may potentially allow us to identify novel members of the Oct4-Nanog complex, leading to better understanding of the regulatory mechanisms behind pluripotency.

Testicular maturation arrest to testis cancer: spectrum of expression of the vitamin D receptor and vitamin D treatment in vitro

PURPOSE

We investigated the qualitative distribution of vitamin D receptor in human testis pathologies and performed an in vitro study of vitamin D receptor expression in a human testis cancer cell line model.

MATERIALS AND METHODS

Qualitative immunohistochemical analysis of vitamin D receptor in testis tumors, normal testis and specimens from infertile patients was performed. The human embryonal carcinoma cell line NT2/D1 (American Type Culture Collection, Manassas, Virginia) was cultured. Vitamin D receptor expression was examined by Western immunoblot analysis after incubating the cells with 250 to 800 nM vitamin D, 10 to 70 nM testosterone, 2 nM calcium or a combination of the 3 products.

RESULTS

Negative controls, synctiotrophoblasts and interstitial stroma did not stain positive for vitamin D receptor. Spermatogenic, Sertoli's, Leydig and tumor cells stained positive in all specimens. Embryonal carcinoma demonstrated more nuclear and cytoplasmic staining than other tumors. Vitamin D receptor expression was seen at 50 kDa in the cell line. Sequential concentrations of vitamin D increased vitamin D receptor expression intensity. Simultaneous addition of vitamin D and testosterone decreased the vitamin D receptor signal, as did testosterone alone. Delayed administration of vitamin D 5 hours after testosterone showed the return of vitamin D receptor expression. A combination of calcium, testosterone and vitamin D showed decreased or no vitamin D receptor expression. Calcium alone increased vitamin D receptor expression at later passages.

CONCLUSIONS

To our knowledge this is the first description of vitamin D receptor in different primary testis pathologies and in an embryonal carcinoma cell line. The in vitro model showed that vitamin D receptor is an active receptor and it is inducible with the addition of vitamin D. Testosterone may be important for vitamin D receptor down-regulation. Calcium may be an important co-factor in vitamin D receptor expression.

Embryonic stem cell transcription factor signatures in the diagnosis of primary and metastatic germ cell tumors

The core embryonic stem cell transcription factors (TFs) OCT3/4 (OCT4), NANOG, and SOX2 have shared as well as nonoverlapping roles in stem cell growth and differentiation. These same TFs are also expressed in various types of human germ cell tumors (GCTs), implicating them in regulation of tumor growth and differentiation. Although NANOG and OCT3/4 are sensitive and specific markers for seminoma and embryonal carcinoma, neither factor aids in the clinically important distinction of seminomatous from nonseminomatous tumors. In contrast, expression profiling data suggest that SOX2 may help with this distinction. To determine if a panel of embryonic stem cell TFs (NANOG, OCT3/4, and SOX2) can facilitate the identification and distinction of seminomatous from nonseminomatous GCTs, we evaluated their expression by immunohistochemistry in primary testicular (n=41) and metastatic retroperitoneal (n=43) GCTs. Our results confirm NANOG and OCT3/4 as sensitive and specific markers for primary seminoma and embryonal carcinoma and demonstrate the novel finding that NANOG is a marker for metastatic GCTs. In addition, SOX2 is expressed in embryonal carcinoma but not pure seminoma and is therefore a useful diagnostic marker for distinguishing seminomatous and nonseminomatous GCTs. In summary, we find that the embryonic stem cell TF signature of seminoma is NANOG+, OCT3/4+, and SOX2-, whereas embryonal carcinoma is NANOG+, OCT3/4+, and SOX2+, and expect these immunohistochemical profiles will facilitate the diagnosis of both primary and metastatic GCTs.

A new role for angiogenin in neurite growth and pathfinding: implications for amyotrophic lateral sclerosis

Mutations in human angiogenin (hANG), an angiogenic member of the RNase A superfamily, have been recently reported in patients with amyotrophic lateral sclerosis (ALS), a progressive late-onset neurodegenerative disorder. However, very little is known about the expression and subcellular distribution of ANG in the nervous system or its role in differentiation. Here we report that mouse angiogenin-1 (mAng-1) is strongly expressed in the developing nervous system during mouse embryogenesis and neuroectodermal differentiation of pluripotent P19 embryonal carcinoma cells. mAng1 is strongly expressed in motor neurons (MNs) in the spinal cord and dorsal root ganglia as well as in post-mitotic MNs derived from P19 cells. We also show for the first time that ANG expression is in the growth cones and neurites. NCI 65828, an inhibitor of the ribonucleolytic activity of hANG, affected pathfinding by P19-derived neurons but not neuronal differentiation. Our findings clearly show that ANG plays an important role in neurite pathfinding and this has implications for ALS.

Outcome of patients with stage II and III nonseminomatous germ cell tumors: results of a single center

BACKGROUND

The prognostic factors in nonseminomatous germ cell tumors have been mainly derived from the analysis of stage I tumors.

AIMS

The aim of this study was to evaluate some prognostic factors and the outcome of patients with stage II and III nonseminomatous germ cell tumors according to risk groups treated between 1993 and 2002.

SETTINGS AND DESIGN

Patients were retrospectively classified as good, intermediate and poor risk groups according to International Germ Cell Cancer Consensus Group.

MATERIALS AND METHODS

Biopsy specimens of 58 patients with stage II and III nonseminomatous germ cell tumors were analyzed by means of tumor histopathology, primary localization site of the tumor, relapse sites, initial serum tumor marker levels, the presence of persistent serum tumor marker elevation and the patients' outcome.

STATISTICAL ANALYSIS

Kruskall Wallis test and Mann-Whitney U test were used to determine the differences between the groups. Kaplan-Meier method was used for survival analysis and log rank test was used to compare the survival probabilities of groups. Cox proportional hazard analysis was used to determine the prognostic factors in univariate and multivariate analysis.

RESULTS

Five-year overall and disease-free survival rates were calculated as 85% and 75% in stage II; 44% and 29% in stage III cases, respectively. Fifty-seven percent of patients were classified in good risk, 9% in intermediate risk and 27% in poor risk groups. Five-year overall survival rates were 97%, 75% and 7% (P<0.001) and disease-free survival rates were 83%, 34% and 7% (P<0.001) in good, intermediate and poor risk groups, respectively. Analysis of the prognostic factors revealed that the localization site of the primary tumor (P<0.001), the initial beta-HCG level (p:0.0048), the presence of yolk sac and choriocarcinoma components in tumor (p:0.003 and p:0.004), relapse sites of tumor (lung versus other than lung) (p:0.003), persistent elevation of serum tumor markers (P<0.001) were significant prognostic factors in univariate analysis. However, in multivariate analysis, only the localization site of tumor (p:0.049) and the relapse site (p:0.003) were found statistically significant.

CONCLUSIONS

This retrospective study revealed that in advanced stage of nonseminomatous germ cell tumors, the outcome is essentially related with the localization site of the tumor and the relapse site.

Qualification of embryonal carcinoma 2102Ep as a reference for human embryonic stem cell research

As the number of human embryonic stem cell (hESC) lines increases, so does the need for systematic evaluation of each line's characteristics and potential. Comparisons between lines are complicated by variations in culture conditions, feeders, spontaneous differentiation, and the absence of standardized assays. These difficulties, combined with the inability of most labs to maintain more than a few lines simultaneously, compel the development of reference standards to which hESC lines can be compared. The use of a stable cell line as a reference standard offers many advantages. A line with a relatively unchanging hESC-like gene and protein expression pattern could be a positive control for developing assays. It can be used as a reference for genomics or proteomics studies, especially for normalizing results obtained in separate laboratories. Such a cell line should be widely available without intellectual property restraints, easily cultured without feeders, and resistant to spontaneous changes in phenotype. We propose that the embryonal carcinoma (EC) line 2102Ep meets these requirements. We compared the protein, gene, and microRNA expression of this cell line with those of hESC lines and alternative reference lines such as the EC line NTERA-2 and the karyotypically abnormal hESC line BG01V. The overall expression profiles of all these lines were similar, with exceptions reflecting the germ cell origins of EC. On the basis of global gene and microRNA expression, 2102Ep is somewhat less similar to hESC than the alternatives; however, 2102Ep expresses more hESC-associated microRNAs than NTERA-2 does, and fewer markers of differentiated fates.

D2-40 immunohistochemistry in the differential diagnosis of seminoma and embryonal carcinoma: a comparative immunohistochemical study with KIT (CD117) and CD30

The distinction between seminoma and embryonal carcinoma based on morphology alone can sometimes be problematic, requiring the use of immunohistochemistry to facilitate diagnosis. D2-40 is a monoclonal antibody that reacts with an oncofetal antigen expressed by fetal germ cells and testicular germ cell tumors. The diagnostic value of D2-40 immunohistochemistry in distinguishing seminoma from embryonal carcinoma has not been determined. D2-40 immunoreactivity was evaluated in a series of testicular germ cell tumors and compared with that of KIT (CD117) and CD30, to assess the relative utility of this marker in discriminating between seminoma and embryonal carcinoma. Forty testicular germ cell neoplasms were examined, which included 19 seminomas, three embryonal carcinomas, three teratomas, one yolk sac tumor, and 14 mixed germ cell tumors. The 14 cases of mixed germ cell tumors contained components of seminoma (n=7), embryonal carcinoma (n=11), teratoma (n=10), yolk sac tumor (n=2), and choriocarcinoma (n=1). All cases of pure seminoma and the seminomatous components of mixed germ cell tumors exhibited positive immunoreactivity for D2-40. Focal positivity for D2-40 was also observed in 29% of the embryonal carcinoma samples. D2-40 immunoreactivity in seminomas was characterized by diffuse membrane staining, whereas for embryonal carcinomas, staining was focal and distributed along the apical surfaces of the neoplastic cells. Immunohistochemical staining for KIT was observed in 92% of the seminoma samples and in none of the embryonal carcinomas. Conversely, CD30 expression was identified in 93% of the embryonal carcinoma samples and in none of the seminomas. Other germ cell components showed no immunoreactivity for D2-40, KIT, or CD30. KIT and CD30 are effective immunohistochemical markers in separating seminoma from embryonal carcinoma. Although a highly sensitive marker for seminomas, D2-40 positivity was also observed in a subset of embryonal carcinomas, thus limiting the utility of this antibody for discriminating between these two malignancies.

Switched alternative splicing of oncogene CoAA during embryonal carcinoma stem cell differentiation

Alternative splicing produces functionally distinct proteins participating in cellular processes including differentiation and development. CoAA is a coactivator that regulates transcription-coupled splicing and its own pre-mRNA transcript is alternatively spliced. We show here that the CoAA gene is embryonically expressed and alternatively spliced in multiple tissues to three splice variants, CoAA, CoAM and CoAR. During retinoic-acid-induced P19 stem cell differentiation, the expression of CoAA undergoes a rapid switch to its dominant negative splice variant CoAM in the cavity of the embryoid body. CoAM functionally inhibits CoAA, and their switched expression up-regulates differentiation marker Sox6. Using a CoAA minigene cassette, we find that the switched alternative splicing of CoAA and CoAM is regulated by the cis-regulating sequence upstream of the CoAA basal promoter. Consistent to this, we show that p54(nrb) and PSF induce CoAM splice variant through the cis-regulating sequence. We have previously shown that the CoAA gene is amplified in human cancers with a recurrent loss of this cis-regulating sequence. These results together suggest that the upstream regulatory sequence contributes to alternative splicing of the CoAA gene during stem cell differentiation, and its selective loss in human cancers potentially deregulates CoAA alternative splicing and alters stem cell differentiation.

Nestin is expressed in the basal/myoepithelial layer of the mammary gland and is a selective marker of basal epithelial breast tumors

Transcriptional profiling has identified five breast cancer subtypes, of which the basal epithelial is most aggressive and correlates with poor prognosis. These tumors display a high degree of cellular heterogeneity and lack established molecular targets, such as estrogen receptor-alpha, progesterone receptor, and Her2 overexpression, indicating a need for definitive diagnostic markers. We present evidence that nestin, a previously described marker of regenerative cells in diverse tissues, is expressed in the regenerative compartment of the normal human mammary gland. Colocalization studies indicate two distinct populations of mammary epithelia that express nestin: one expressing cytokeratin 14 (CK14) and DeltaN-p63 and another expressing desmin. Immunohistochemical analysis indicates that DeltaN-p63 and nestin are coordinately expressed during pregnancy in the murine mammary gland. In the embryonal carcinoma cell line NT2/D1, ectopic DeltaN-p63-alpha disrupts retinoic acid-induced differentiation, thereby preserving expression of nestin; however, small interfering RNA-mediated ablation of nestin is insufficient to promote differentiation, indicating that whereas nestin may identify cells within the regenerative compartment of the mammary gland, it is insufficient to block differentiation and preserve replicative capacity. Immunohistochemical analysis of basal epithelial breast tumors, including those shown to carry BRCA1 mutations, indicates robust expression of nestin and CK14, punctate expression of p63, and low to undetectable levels of desmin expression. Nestin was not detected in other breast cancer subtypes, indicating selectivity for basal epithelial breast tumors. These studies identify nestin as a selective marker of the basal breast cancer phenotype, which displays features of mammary progenitors.

[Embryonic hepatic sarcoma in children: aspects of morphological diagnosis]

13 cases of embryonic undifferentiated sarcoma of the liver were examined. The tumor was detected in children: 50% being between 5-6 years of age and no sex domination was found. The tumors were solitary, large, well demarcated and had cystic areas of gelatinous degeneration. The tumor was composed of atypical round, stellate, spindle and epithelioid-like cells that were loosely arranged in a myxoid stroma. Entrapped bile ducts were commonly present. Electron microscopic and immunohistochemical findings showed no clear-cut differentiation of embryonic sarcoma cells.

Role of retinoic acid in the differentiation of embryonal carcinoma and embryonic stem cells

Retinoic acid (RA), the most potent natural form of vitamin A, plays an important role in many diverse biological processes such as embryogenesis and cellular differentiation. This chapter is a review of the mechanism of action of RA and the role of specific RA-regulated genes during the cellular differentiation of embryonal carcinoma (EC) and embryonic stem (ES) cells. RA acts by binding to its nuclear receptors and inducing transcription of specific target genes. The most studied mouse EC cell lines include F9 cells, which can be induced by RA to differentiate into primitive, parietal, and visceral endodermal cells; and P19 cells, which can differentiate to endodermal and neuronal cells upon RA treatment. ES cells can be induced to differentiate into a number of different cell types; many of which require RA treatment. Over the years, many RA-regulated genes have been discovered in EC and ES cells using a diverse set of techniques. Current research focuses on the elucidation how these genes affect differentiation in EC and ES cells using a variety of molecular biology approaches. However, the exact molecule events that lead from a pluripotent stem cell to a fully differentiated cell following RA treatment are yet to be determined.

Brain-specific BNIP-2-homology protein Caytaxin relocalises glutaminase to neurite terminals and reduces glutamate levels

Human Cayman ataxia and mouse or rat dystonia are linked to mutations in the genes ATCAY (Atcay) that encode BNIP-H or Caytaxin, a brain-specific member of the BNIP-2 family. To explore its possible role(s) in neuronal function, we used protein precipitation and matrix-assisted laser desorption/ionisation mass spectrometry and identified kidney-type glutaminase (KGA) as a novel partner of BNIP-H. KGA converts glutamine to glutamate, which could serve as an important source of neurotransmitter. Co-immunoprecipitation with specific BNIP-H antibody confirmed that endogenous BNIP-H and KGA form a physiological complex in the brain, whereas binding studies showed that they interact with each other directly. Immunohistochemistry and in situ hybridisation revealed high BNIP-H expression in hippocampus and cerebellum, broadly overlapping with the expression pattern previously reported for KGA. Significantly, BNIP-H expression was activated in differentiating neurons of the embryonic carcinoma cell line P19 whereas its overexpression in rat pheochromocytoma PC12 cells relocalised KGA from the mitochondria to neurite terminals. It also reduced the steady-state levels of glutamate by inhibiting KGA enzyme activity. These results strongly suggest that through binding to KGA, BNIP-H could regulate glutamate synthesis at synapses during neurotransmission. Thus, loss of BNIP-H function could render glutamate excitotoxicity or/and deregulated glutamatergic activation, leading to ataxia, dystonia or other neurological disorders.

Embryonal carcinoma producing DU-PAN-2 with burned-out phenomenon in the testis

A burned-out testicular tumor with lung and lymph node metastases presented high serum levels of DU-PAN-2. However, the serum levels of CA19-9, alpha-fetoprotein, beta-human chorionic gonadotropin, and sialyl Lewis X were normal. A biopsy of the cervical lymph nodes revealed embryonal carcinoma. Four courses of chemotherapy, including cisplatin, etoposide, and bleomycin, normalized the level of DU-PAN-2, and the metastatic lesions disappeared. This is the second reported case of an embryonal carcinoma producing DU-PAN-2. The secretor and Lewis gene typings, which affect the normal serum ranges of CA19-9 and DU-PAN-2, were determined.

Immunohistochemical detection of p63 in testicular germ cell neoplasia

p63 is a novel transcription factor-encoding gene with sequence homology to p53. p63 proteins have epithelial stem-cell regulatory functions and play a critical role in tissue development. Study of p63 expression in testicular germ cell tumors has been limited. Thirty-four archival cases of testicular germ cell neoplasia were examined and stained with monoclonal anti-p63 antibody 4A4 using standard methods. Included were 19 seminomas, 1 pure teratoma, 3 pure embryonal carcinomas, 1 pure yolk sac tumor, and 10 mixed germ cell tumors. p63 staining was consistently positive in teratomas in areas of squamous differentiation and in basal reserve-like cells in foci of respiratory/endodermal differentiation. Strong p63 staining was observed within cytotrophoblasts of choriocarcinoma (1/1), whereas focal positivity was detected in embryonal carcinomas (4/10) and yolk sac tumors (2/5). Seminomas and intratubular germ cell neoplasia were p63-negative. These findings may suggest the presence of pluripotent p63-positive stem cell-like nests in yolk sac tumors and embryonal carcinomas or may represent areas of an occult teratoma phenotype undetectable histopathologically on hemotoxylin-eosin sections. p63 positivity in cytotrophoblasts of choriocarcinoma is consistent with gynecologic studies, possibly reflecting the role of p63 in the oncogenesis of neoplastic trophoblasts. The consistent p63 negativity in seminomas may reflect a precommitted embryonic precursor-like phenotype.

Suppression of PTEN expression during aggregation with retinoic acid in P19 mouse embryonal carcinoma cells

Apoptosis is thought to be involved in the maintenance of cellular homeostasis, as well as various pathological processes. However, little information is available about the regulation of apoptosis during the aggregation stage of P19 embryonal carcinoma (EC) cells. Here we report that aggregation-induced apoptosis is markedly attenuated by treatment with retinoic acid (RA). PTEN (phosphatase and tensin homolog deleted on chromosome 10) expression was down-regulated during the aggregation phase of P19 EC cells in the presence, but not in the absence, of RA. Suppression of PTEN expression during the aggregation was accompanied by increased phosphorylation of serine/threonine kinase Akt and glycogen synthase kinase-3beta (GSK-3beta). Our results suggest that RA attenuates the induction of apoptosis during the aggregation phase of P19 EC cells, probably by suppressing PTEN expression.

Suz12 binds to silenced regions of the genome in a cell-type-specific manner

Suz12 is a component of the Polycomb group complexes 2, 3, and 4 (PRC 2/3/4). These complexes are critical for proper embryonic development, but very few target genes have been identified in either mouse or human cells. Using a variety of ChIP-chip approaches, we have identified a large set of Suz12 target genes in five different human and mouse cell lines. Interestingly, we found that Suz12 target promoters are cell type specific, with transcription factors and homeobox proteins predominating in embryonal cells and glycoproteins and immunoglobulin-related proteins predominating in adult tumors. We have also characterized the localization of other components of the PRC complex with Suz12 and investigated the overall relationship between Suz12 binding and markers of active versus inactive chromatin, using both promoter arrays and custom tiling arrays. Surprisingly, we find that the PRC complexes can be localized to discrete binding sites or spread through large regions of the mouse and human genomes. Finally, we have shown that some Suz12 target genes are bound by OCT4 in embryonal cells and suggest that OCT4 maintains stem cell self-renewal, in part, by recruiting PRC complexes to certain genes that promote differentiation.

Inclusion of a matrix-attached region in a 7SK pol III vector increases the efficiency of shRNA-mediated gene silencing in embryonic carcinoma cells

RNA interference is a widely used tool for analysis of gene function in mammalian cells. Stable knockdown of specific target genes can be maintained in cell lines and live organisms using vector-based delivery of short hairpins (shRNAs) driven by RNA polymerase III promoters. Here we describe a vector incorporating the human 7SK promoter for shRNA-mediated gene silencing in the P19 embryonic carcinoma stem cell line. Our preliminary experiments with the 7SK shRNA expression vector indicated that its activity could be hindered by random genomic integration. In order to counter this inhibitory mechanism, we inserted a matrix-attached region sequence to generate an episomal vector system. We compared the effects of insertion versus exclusion of the MAR sequence on the shRNA-mediated gene-specific silencing of the beta-tubulin III and Cyclophilin A genes. While the MAR sequence is not strongly correlated with the episomal status of the expression vector, our studies indicate that inclusion of the MAR element significantly enhances the stability of shRNA-mediated gene silencing in the P19 stem cells.

Expression of SpanX proteins in normal testes and in testicular germ cell tumours

We investigated the expression of the SpanX protein family in cells of normal testes and in testicular germ cell tumours, mainly seminomas and embryonal carcinomas, using an immunohistochemical approach. Most of the normal germ cells, belonging to spermatogonial and primary spermatocytic classes, showed a strong nuclear positivity. In contrast, post-meiotic germ cells showed diffused cytoplasmic and sometimes also perinuclear localization of the signal. The vast majority of cells were also positive in eight seminomas, six embryonal cell carcinomas and one teratocarcinoma. In all seminomas, nuclei were either exclusively or preferentially labelled; whereas, the nuclear signal intensity decreased in parallel with the appearance of some cytoplasmic staining in embryonal carcinomas. In conclusion, these data suggest that the SpanX protein family is not exclusively expressed post-meiotically and that seminomas and embryonal carcinomas may originate from SpanX-positive carcinoma-in-situ cell.

Following the Differentiation of Human Pluripotent Stem Cells by Proteomic Identification of Biomarkers

Following the differentiation of cultured stem cells is often reliant on the expression of genes and proteins that provide information on the developmental status of the cell or culture system. There are few molecules, however, that show definitive expression exclusively in a specific cell type. Moreover, the reliance on a small number of molecules that are not entirely accurate biomarkers of particular tissues can lead to misinterpretation in the characterization of the direction of cell differentiation. Here we describe the use of technology that examines the mass spectrum of proteins expressed in cultured cells as a means to identify the developmental status of stem cells and their derivatives in vitro. This approach is rapid and reproducible and it examines the expression of several different biomarkers simultaneously, providing a profile of protein expression that more accurately corresponds to a particular type of cell differentiation.

DMRT-1 expression during NEC8 human embryonic carcinoma cell differentiation

To elucidate the relationship between dsx and mab-3 related transcription factor 1 (Dmrt-1) and differentiation, alteration in mRNA levels during differentiation of NEC8 human embryonic carcinoma cells was investigated. After stimulation with 50 nM phorbol 12-myristate 13-acetate (PMA), the cells differentiated into cells with mesenchymal characteristics and upregulated Dmrt-1 mRNA, possibly through the protein kinase C/mitogen-activated protein kinase/activated protein-1 signaling pathway. Conversely, knockdown of Dmrt-1 by small interfering RNA resulted in cell morphology that was different from that after PMA treatment. These results indicated that Dmrt-1 expression was apparently associated with the differentiation of NEC8, and this cell line may be a helpful in vitro tool to clarify the role of Dmrt-1 in the differentiation process.

CD30 is a survival factor and a biomarker for transformed human pluripotent stem cells

The application of human embryonic stem (hES) cells in regenerative medicine will require rigorous quality control measures to ensure the safety of hES cell-derived grafts. During propagation in vitro, hES cells can acquire cytogenetic abnormalities as well as submicroscopic genetic lesions, such as small amplifications or deletions. Many of the genetic abnormalities that arise in hES cell cultures are also implicated in human cancer development. The causes of genetic instability of hES cells in culture are poorly understood, and commonly used cytogenetic methods for detection of abnormal cells are capable only of low-throughput analysis on small numbers of cells. The identification of biomarkers of genetic instability in hES cells would greatly facilitate the development of culture methods that preserve genomic integrity. Here we show that CD30, a member of the tumor necrosis factor receptor superfamily, is expressed on transformed but not normal hES cells, and that CD30 expression protects hES cells against apoptosis.

Embryonic stem (ES) cells and embryonal carcinoma (EC) cells: opposite sides of the same coin

Embryonal carcinoma (EC) cells are the stem cells of teratocarcinomas, and the malignant counterparts of embryonic stem (ES) cells derived from the inner cell mass of blastocyst-stage embryos, whether human or mouse. On prolonged culture in vitro, human ES cells acquire karyotypic changes that are also seen in human EC cells. They also 'adapt', proliferating faster and becoming easier to maintain with time in culture. Furthermore, when cells from such an 'adapted' culture were inoculated into a SCID (severe combined immunodeficient) mouse, we obtained a teratocarcinoma containing histologically recognizable stem cells, which grew out when the tumour was explanted into culture and exhibited properties of the starting ES cells. In these features, the 'adapted' ES cells resembled malignant EC cells. The results suggest that ES cells may develop in culture in ways that mimic changes occurring in EC cells during tumour progression.

Endodermal differentiation of murine embryonic carcinoma cells by retinoic acid requires JLP, a JNK-scaffolding protein

Retinoic acid (RA) is a morphogen that induces endodermal differentiation of murine P19 embryonic carcinoma cells. RA-induced differentiation of P19 cells has been used as a model system to define the differentiation programs of pluripotent stem cells. Using this system it has been shown that G alpha13--the alpha-subunit of the heterotrimeric G protein G13--and its activation of JNK-module are critically required for the endodermal differentiation of P19 cells. However, the mechanism through which G alpha13 is linked to JNK-module is unknown. Here, we report that RA stimulates the expression of JNK-interacting leucine zipper protein (JLP), a newly identified JNK-scaffolding protein and its critical role in RA-mediated endodermal differentiation. Our results indicate that there is a physical association between JLP and G alpha13 in RA-stimulated P19 cells. More interestingly, silencing JLP abrogates RA-mediated endodermal differentiation of P19 cells analogous to the effects seen with the silencing of G alpha13 or JNK. Therefore, our studies presented here identify for the first time, a novel role for a newly identified scaffolding protein in RA-mediated endodermal differentiation, providing a new signaling conduit to transmit signals from RA to JNK module.

Multicentre risk-adapted management for stage I non-seminomatous germ cell tumours

BACKGROUND

The Spanish Germ Cell Group is composed of 60 centres. Our challenge was to define a surveillance protocol that would be safe and suitable regardless of population size or geographic coverage.

METHODS

From January 1994 to January 2004, 589 patients with stage I non-seminomatous germ cell tumours entered a risk-adapted surveillance protocol after orchiectomy. Patients with vascular or local invasion of adjacent structures (231/589; 39%) received two cycles of BE400P (bleomycin 30 U/week, etoposide 100 mg/m2 x4, cisplatinum 25 mg/m2 x4). Other patients (358/589; 61%) were kept on close follow-up (chest X-ray; serum tumour markers: first year every 2 months, second year every 3 months, third year every 4 months; abdominal computed tomography scans at every other outpatient control). The outcomes selected for the study were feasibility, relapse rate and number of patients lost to follow-up and mortality.

RESULTS

Median follow-up was 40 months. In the surveillance group, 21 patients were lost to follow-up. In the chemotherapy group, two patients relapsed at 12 and 14.5 months and they are presently free of disease. In the surveillance group, 71 (19%) patients relapsed, of which 55 (71%) relapsed within the first year. Five (1.4%) patients died of their cancer. Factors associated with relapse were embryonal carcinoma and vascular invasion in patients who refused chemotherapy.

CONCLUSIONS

Our risk-adapted surveillance protocol provided a low rate of recurrences.

The CDK inhibitor p27 enhances neural differentiation in pluripotent NTERA2 human EC cells, but does not permit differentiation of 2102Ep nullipotent human EC cells

Embryonal carcinoma (EC) cells, the stem cells of teratocarcinomas, are the malignant counterparts of pluripotent embryonic stem (ES) cells, but commonly exhibit a reduced ability to differentiate, presumably because of continual selection for genetic changes that alter the balance between self-renewal, differentiation and apoptosis in favour of self-renewal. To explore the nature of the genetic changes that promote nullipotency, we have compared two human EC cell lines, a 'nullipotent' line, 2102Ep, and a 'pluripotent' line, NTERA2. A hybrid derived by fusion of these cells differentiates in response to retinoic acid but, unlike the parental NTERA2 line, does not form terminally differentiated neurons. This implies that the nullipotent EC cell line, 2102Ep, differs in expression of at least two functions in comparison with the NTERA2 pluripotent line, one affecting commitment to differentiation, and one affecting terminal neural differentiation. We have now investigated the possible role of the CDK inhibitor, p27kip1 (p27) in commitment and terminal differentiation. In NTERA2, but not in 2102Ep cells, retinoic acid induces up-regulation of p27 expression, suggesting that 2102Ep cells lack this capacity. However, constitutive expression of a p27 transgene does not overcome the block to differentiation in the 2102Ep parental cells; commitment to differentiation must be blocked elsewhere. On the other hand, constitutive over-expression of p27 from a transgene enhances the neural differentiation of NTERA2 cells. Our results suggest that p27 plays a role in terminal neuronal differentiation of human EC cells, but not in their initial commitment to differentiation, and that other factors, possibly Cyclin D2, specifically limit its ability to promote neural differentiation.