Expression of a specific mouse germ cell nuclear antigen (GCNA1) by early embryonic testicular teratoma cells in 129/Sv-Sl/+ mice

Spontaneous testicular teratomas which develop at a high rate in 129/Sv-Sl/+ mice are thought to be derived from germ cells. The teratomas present initially as groups of atypical germ-like cells within seminiferous cords of the 15.5 days post coitum (dpc) embryonic testes. These pluripotent teratoma stem cells are capable of differentiating into many kinds of tissues in adult mice. In this immunohistochemical study, we have examined the testes of 129/Sv-Sl/+ mice to determine whether the teratoma cells which developed in these gonads retain the nuclear antigen GCNA1. GCNA1 is a 110 kDa mouse Germ Cell Nuclear Antigen recognized by a rat monoclonal antibody 10D9G11. GCNA1 is expressed in mouse germ cells after they migrate into the genital ridge (11.5 dpc), throughout embryonic development until postnatally germ cells arrive at the diplotene/dictyate stage of the first meiotic division, when it is no longer expressed. Early foci (16.5 dpc) of teratoma stem cells in 129/Sv-Sl/+ mice strongly express GCNA1, but down regulate GCNA1 expression by 19.5 dpc. The loss of GCNA1 expression from teratoma stem cells late in embryonic development is in contrast to embryonic gonocytes which retain GCNA1 expression throughout fetal development. All postnatal undifferentiated and differentiated teratoma cells did not appear to express GCNA1. The expression of the germ cell specific nuclear antigen GCNA1 in early teratoma stem cells further demonstrated that the testicular teratomas originate from early germ cells. The stronger reaction of monoclonal antibody 10D9G11 to GCNA1 within early teratoma cells compared to normal germ cells makes GCNA1 useful in identifying early embryonic tumor foci.     

Telomerase activity in germ cell cancers and mature teratomas.

BACKGROUND: An inverse relationship has been reported between the presence of telomerase enzymatic activity and the induction of differentiation in human tumor cell lines. Male germ cell tumors represent an attractive clinical model to assess this relationship further because high telomerase activity is present in normal germ cell progenitors and in embryonal carcinomas that can differentiate into mature teratomas. To investigate how telomerase activity and the differentiation state of germ cell tumors are related, telomerase activities and telomere lengths were measured in benign testicular tissues, germ cell cancers, and mature or immature teratomas. METHODS: By use of a modified telomeric repeat amplification protocol (TRAP) assay, telomerase activity was measured in four specimens of benign testicular tissue, in 27 germ cell cancers, in seven mature teratomas, and in one immature teratoma. Telomere lengths were measured in all specimens by restriction digestion of genomic DNA and Southern blot hybridization analysis. Associations between telomerase activity and tissue histopathology were assessed with two-sided Fisher's exact tests. RESULTS: Telomerase activity was detected in all examined germ cell cancers and in the benign testicular tissue specimens. In marked contrast, telomerase activity was not detected in any mature teratoma (P<.0001). Very long telomeres were detected in some mature teratomas, consistent with telomerase repression as a late event in teratoma formation. The immature teratoma, with malignant transformation, had high telomerase activity. CONCLUSION: Telomerase is active in germ cell cancers and repressed in mature teratomas. The absence of telomerase activity may contribute to the limited proliferative capacity of mature teratomas. These findings support the existence of an inverse relationship between telomerase activity and the differentiation state of clinical germ cell tumors.     

Imaging of ovarian teratomas: Appearances and complications

Ovarian teratomas are the most common germ cell neoplasm. Subtypes of teratoma include mature cystic, immature and the monodermal teratomas. The benign cystic teratoma shows typical imaging manifestations and can be complicated by torsion, rupture and uncommonly malignant degeneration. Uncommon subtypes of teratomas include the immature, which is usually malignant at diagnosis. The growing teratoma syndrome is an uncommon complication reported in patients treated for immature teratomas. The monodermal teratomas which include the struma ovarii may also have specific imaging characteristics that should be recognised on imaging. This paper aims to provide a comprehensive review describing the spectrum of imaging findings of these ovarian tumours and associated complications     

A recessive mutation (ter) causing germ cell deficiency and a high incidence of congenital testicular teratomas in 129/Sv-ter mice

The genetic basis of a germ cell deficiency, accompanied by a high incidence of testicular teratomas, was studied in strain 129/Sv-ter mice (formerly designated "129/terSv"). Germ cell deficiency became more severe with advancing age in males, and they were sterile whether or not they had bilateral teratomas. Germ cell-deficient testes were smaller than normal except when the testes had teratomas. In females the ovaries were smaller than normal, but the germ cell deficiency did not progress and most were fertile. The germ cell deficiency resulted from the homozygous state of a recessive mutant gene designated "teratoma (ter)." Matings between females with small ovaries and homozygous normal males produced no germ cell-deficient offspring. When F1 offspring with normal gonads were mated together, germ cell-deficient F2 animals appeared at a frequency close to 1 in 4. When females with small ovaries (ter/ter) were mated with heterozygous males (ter/+), half of the offspring were germ cell deficient. It was concluded that the genetic factor is a single recessive gene. The incidence of teratomas in +/+ strain 129/Sv-ter males was 1.4% (3/216), and all teratomas were unilateral. Seventeen percent (20/117) of heterozygous males had teratomas, of which 18 were unilateral and 2 were bilateral. Ninety-four percent (167/178) of homozygous ter/ter males had teratomas, of which 75% were bilateral. Introduction of the mutant gene ter onto the C57BL/6 genetic background resulted in germ cell deficiency in homozygotes, but it reduced considerably the teratoma incidence in ter/ter males.     

Interphase fluorescence in situ hybridization analysis of chromosome 12p abnormalities is useful for distinguishing epidermoid cysts of the testis from pure mature teratoma.

PURPOSE: The distinction of epidermoid cyst of the testis from teratoma is of critical importance because the former is benign and the latter is a malignant tumor that may have associated metastasis of either teratomatous or non-teratomatous germ cell tumor types. Chromosome 12p abnormalities are seen in the vast majority of testicular germ cell tumors of adults and are present in all histologic subtypes. In this study, we investigated the clinical utility of interphase fluorescence in situ hybridization (FISH) analysis of chromosome 12p abnormalities for distinguishing epidermoid cysts of the testis from pure mature teratoma. EXPERIMENTAL DESIGN: Sixteen testicular epidermoid cysts and 17 testicular teratomas were investigated for isochromosome 12p [i(12p)] and 12p overrepresentation using interphase FISH analysis. RESULTS: Neither i(12p) nor 12p overrepresentation were observed in 16 epidermoid cyst cases, whereas i(12p) was detected in 76% of teratomas and 12p overrepresentation was identified in 29% of teratomas. Overall, 88% of testicular teratomas had chromosome 12p abnormalities. CONCLUSIONS: FISH identification of i(12p) and/or 12p overrepresentation in routinely processed surgical specimens is a useful ancillary diagnostic tool in distinguishing testicular epidermoid cysts from teratoma.     

Histogenetic analysis of ovarian germ cell tumors by DNA fingerprinting.

The histogenesis of ovarian germ cell tumors (11 mature teratomas, three malignant transformations of mature teratomas, two immature teratomas, and four dysgerminomas) was investigated genetically using minisatellite DNA probes 33.15 and 33.6 for person-specific restriction fragment length polymorphism (DNA fingerprint) analysis. The DNA fingerprints of six ovarian teratomas were identical with those of mononuclear cells from each host, while some polymorphic bands observed in the host mononuclear cells were lost in the DNA fingerprints of the other five cases. The cases of malignant transformation of mature teratoma and immature teratoma showed that some polymorphic bands of DNA fingerprints from the host mononuclear cells were absent in the tumor tissues. In four cases with dysgerminomas, the DNA fingerprints of tumors were completely identical with those of the respective host mononuclear cells. The present results suggest that mature cystic teratomas of the ovary arise from germ cells arrested at various stages of meiosis, while immature teratomas are derived from postmeiotic germ cells. Malignant transformation may occur exclusively in the mature teratomas arising from postmeiotic germ cells. Dysgerminomas develop from premeiotic oogonia (primordial germ cells). Thus, DNA fingerprints are a useful and sensitive tool for identifying the pathogenesis of germ cell tumours.     

More Cases of Benign Testicular Teratomas are Detected in Adults than in Children. A Clinicopathological Study of 543 Testicular Germ Cell Tumor Cases

Benign testicular teratomas are always thought to be pediatric neoplasms and previously all the teratoid tumors in the adult testis regarded as malignant. Recently, three publications reported benign testicular teratomas in adulthood and the latest WHO classification refers them as “prepubertal type of teratomas” which rarely appear in adulthood. These neoplasms behave benign and seemingly analogous independently whether they appear in pre- or postpubertal patients. The aim of our study was to investigate the frequency of benign testicular teratomas both in children and adults. 593 cases of testicular neoplasms were found in a period of 17 years ranging from 1998 to 2014 in the archive of our department (Department of Pathology, Medical Center, Pécs University). 543 cases diagnosed as germ cell tumor which have all been further evaluated in conjunction with the clinical data available. Of all germ cell tumor cases 14 (2.5 %) were pure teratomas. Ten out of 14 were the WHO-defined “conventional” teratoma, 4 of the 14 were the “benign or the so called prepubertal type” from which three occurred in adult patients. Only one of the 14 occurred in childhood, indicating that benign prepubertal type teratomas –which are regarded generally as childhood tumors- are more frequently detected in adults than in children. Benign adult testicular teratomas comprised 21 % of all pure teratoma cases in our series. Practicioners in the field have to be aware of its existence also in adulthood to avoid overtreatment and not to expose their patients to unnecessary chemotherapy, retroperitoneal lymphadenectomy (RLA) and the potential complications of these interventions.     

The effect of in utero ethinyl oestradiol exposure on the risk of cryptorchid testis and testicular teratoma in mice

Epidemiological findings indicate that both cryptorchid testis and testicular germ cell cancer may be a result of high maternal oestrogen levels early in pregnancy. An experiment was conducted with a mouse strain (129 Sv-S1 C P) in which the males are susceptible to testicular teratomas to determine if the frequency of undescended testis and testicular teratoma in male offspring could be increased by administration of ethinyl oestradiol (EE) to pregnant mice before day 13 of gestation. This point in gestation marks the completion of the migration of germ cells to the gonadal ridge in mice and other studies with these mice have shown that the tumours are initiated in this critical time period. EE mixed with corn oil was administered by subcutaneous injection in doses of 0.02 (n = 76) and 0.2 (n = 102) mg kg-1 of body weight on gestational days 11 and 12. These mice were allowed to deliver their offspring and the males were killed at 15 days of age. Since the tumours are present from birth, this amount of time was allowed to permit the tumours to reach sufficient size for easy visual identification. Compared to controls (n = 63), who received corn oil alone, the treated mothers produced offspring who were significantly more likely to have a cryptorchid testis (P = 0.0001) and who had an increased risk, although not significant, of a testicular teratoma.     

Expression of HER-2/neu in testicular tumors

BACKGROUND: Although the overexpression of the Epidermal Growth Factor Receptor 2 (EGFR-2, HER-2/neu, c-erbB-2) in malignancies might predict chemoresistance and poor prognosis, its clinical relevance has not been widely studied and determined in testicular tumors. PATIENTS AND METHODS: Since teratomas are relatively chemoresistant tumors, we evaluated the HER-2/neu receptor status of 28 primary testicular tumors (7 pure teratomas, 21 mixed germ cell tumors containing teratomatous components) using a standardized immunohistochemical method (HercepTest Kit). RESULTS: Seven (25%) out of 28 non-seminomatous germ cell tumors showed HER-2/neu positivity. The teratomatous components of mixed GCTs showed HER-2/neu overexpression in 5 cases. Three of the 5 choriocarcinoma components of mixed tumors overexpressed HER-2/neu. In one case (teratoma + choriocarcinoma) both components showed HER-2/neu overexpression. No HER-2/neu overexpression was detected in other, less differentiated histological subtypes. Among the HER-2/neu-positive cases, 3 patients are in complete remission, 3 patients are in partial remission and one patient died after primary chemotherapy. CONCLUSION: Twenty-five percent of the non-seminomatous germ cell tumors which contain teratomatous components overexpress HER-2/neu protein. The overexpression is restricted to the more differentiated histotypes. Further molecular investigations and clinicopathological studies are necessary to determine the correlation between HER-2/neu overexpression and clinical resistance of testicular tumors.     

Inhibition of microRNA‐214 ameliorates hepatic fibrosis and tumor incidence in platelet‐derived growth factor C transgenic mice

Differentially regulated microRNA (miRNA) are associated with hepatic fibrosis; however, their potential usefulness for blocking hepatic fibrosis has not been exploited fully. We examined the expression of miRNA in the liver of a transgenic mouse model in which platelet‐derived growth factor C (PDGF‐C) is overexpressed (Pdgf‐c Tg), resulting in hepatic fibrosis and steatosis and the eventual development of hepatocellular carcinoma (HCC). Robust induction of miR‐214 correlated with fibrogenesis in the liver of Pdgf‐c Tg mice, atherogenic high‐fat diet‐induced NASH mice, and patients with chronic hepatitis B or C. Pdgf‐c Tg mice were injected with locked nucleic acid (LNA)‐antimiR‐214 via the tail vein using Invivofectamine 2.0 and the degree of hepatic fibrosis and tumor incidence were evaluated. Pdgf‐c Tg mice treated with LNA‐antimiR‐214 showed a marked reduction in fibrosis and tumor incidence compared with saline or LNA‐miR‐control‐injected control mice. In vitro, LNA‐antimiR‐214 significantly ameliorated TGF‐β1‐induced pro‐fibrotic gene expression in Lx‐2 cells. MiR‐214 targets a negative regulator of EGFR signaling, Mig‐6. Mimic‐miR‐214 decreased the expression of Mig‐6 and increased the levels of EGF‐mediated p‐EGFR (Y1173 and Y845) and p‐Met (Tyr1234/1235) in Huh‐7 cells. Conversely, LNA‐antimiR‐214 repressed the expression of these genes. In conclusion, miR‐214 appears to participate in the development of hepatic fibrosis by modulating the EGFR and TGF‐β signaling pathways. LNA‐antimiR‐214 is a potential therapy for the prevention of hepatic fibrosis.     

Teratoma Formation in Immunocompetent Mice After Syngeneic and Allogeneic Implantation of Germline Capable Mouse Embryonic Stem Cells

Background: Embryonic stem cells (ESCs) have the potential to form teratomas when implanted intoimmunodeficient mice, but data in immunocompetent mice are limited. We therefore investigated teratomaformation after implantation of three different mouse ESC (mESC) lines into immunocompetent mice. Materialsand Methods: BALB/c mice were injected with three highly germline competent mESCs (129Sv, BALB/c andC57BL/6) subcutaneously or under the kidney capsule. After 4 weeks, mice were euthanized and examinedhistologically for teratoma development. The incidence, size and composition of teratomas were compared usingPearson Chi-square, t-test for dependent variables, one-way analysis of variance and the nonparametric Kruskal-Wallis analysis of variance and median test. Results: Teratomas developed from all three cell lines. The incidenceof formation was significantly higher under the kidney capsule compared to subcutaneous site and occurred inboth allogeneic and syngeneic mice. Overall, the size of teratoma was largest with the 129Sv cell line and underthe kidney capsule. Diverse embryonic stem cell-derived tissues, belonging to the three embryonic germ layers,were encountered, reflecting the pluripotency of embryonic stem cells. Most commonly represented tissueswere nervous tissue, keratinizing stratified squamous epithelium (ectoderm), smooth muscle, striated muscle,cartilage, bone (mesoderm), and glandular tissue in the form of gut- and respiratory-like epithelia (endoderm).Conclusions: ESCs can form teratomas in immunocompetent mice and, therefore, removal of undifferentiatedESC is a pre-requisite for a safe use of ESC in cell-based therapies. In addition the genetic relationship of theorigin of the cell lines to the ability to transplant plays a major role.     

Clonal evidence for the development of neuroblastoma with extensive copy-neutral loss of heterozygosity arising in a mature teratoma

Mature teratomas are usually benign tumors that rarely undergo malignant transformation. We report an advanced neuroblastoma arising in a mature teratoma of the ovary. Whole-exome sequencing identified extensive copy-neutral loss of heterozygosity (LOH) in both neuroblastoma and teratoma elements, suggesting that the neuroblastoma evolved from the teratoma. In addition, several truncating germline heterozygous variants in tumor suppressor genes, including RBL2 and FBXW12, became homozygous as a result of LOH. Collectively, we speculate that extensive LOH in teratoma cells may force heterozygous germline variants to become homozygous, which, in turn, may contribute to the development of neuroblastoma with the acquisition of additional chromosomal changes.     

GANP protein encoded on human chromosome 21/mouse chromosome 10 is associated with resistance to mammary tumor development

Human chromosome 21 is known to be associated with the high risk of hematological malignancy but with resistance to breast cancer in the study of Down syndrome. In human cancers, we previously observed the significant alterations of the protein expression encoded by the ganp/MCM3AP gene on human chromosome 21q22.3. Here, we investigated GANP protein alterations in human breast cancer samples (416 cases) at various stages by immunohistochemical analysis. This cohort study clearly showed that expression of GANP is significantly decreased in human breast cancer cases with poor prognosis as an independent risk factor (relapse‐free survival, hazard ratio = 2.37, 95% confidence interval, 1.27–4.42, P = 0.007 [univariate analysis]; hazard ratio = 2.70, 95% confidence interval, 1.42–5.13, P = 0.002 [multivariate analysis]). To investigate whether the altered GANP expression is associated with mammary tumorigenesis, we created mutant mice that were conditionally deficient in the ganp/MCM3AP gene using wap‐cre recombinase transgenic mice. Mammary gland tumors occurred at a very high incidence in female mammary gland‐specific GANP‐deficient mice after severe impairment of mammary gland development during pregnancy. Moreover, tumor development also occurred in female post parous GANP‐heterodeficient mice. GANP has a significant role in the suppression of DNA damage caused by estrogen in human breast cancer cell lines. These results indicated that the GANP protein is associated with breast cancer resistance.     

DNA topoisomerase I and II expression in drug resistant germ cell tumours

A small number of testicular germ cell tumours are refractory to current chemotherapy regimens. DNA topoisomerase I is the target for several new drugs and a potential candidate treatment for chemorefractory germ cell tumours. DNA topoisomerase II alpha is the target for etoposide, which is currently used regularly in germ cell tumour treatment. The expression of DNA topoisomerase I and II alpha were therefore assessed immunohistochemically in a range of testicular tumours, especially those with persistent malignant elements on retroperitoneal lymph node dissection. Pre-chemotherapy orchidectomy specimens were matched with post-chemotherapy retroperitoneal lymph node dissections to examine changes in expression. There was considerable variation in the expression of topoisomerase I in different tumour types. Both yolk sac tumours and teratoma, mature showed universal expression of topoisomerase I, while 38% of seminomas and 30% of embryonal carcinomas were positive. Strong topoisomerase II alpha expression was found in embryonal carcinoma. There was a negative correlation between topoisomerase I and II alpha expression (P=0.004) and downregulation of topoisomerase II alpha after chemotherapy (P=0.02). Topoisomerase I expression appears to increase in those cases with residual teratoma, mature, but is largely unchanged in those cases remaining as embryonal carcinoma. These results suggest that topoisomerase I inhibitors may be useful in chemorefractory germ cell tumours, especially yolk sac tumours and where there are unresectable residual teratoma, mature deposits.