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H Stoop

Publications and source records attributed to H Stoop.

9 recordsLinked to original sources
PubMed2006

The PTEN gene in locally progressive prostate cancer is preferentially inactivated by bi-allelic gene deletion.

PTEN is frequently inactivated during the development of many cancers, including prostate cancer, and both bi-allelic and mono-allelic PTEN inactivation may contribute to tumorigenesis. PTEN mutations in clinical cancer specimens can easily be recorded but mono- or bi-allelic gene deletions are often difficult to assess. We performed a comprehensive study to detect PTEN inactivation in 40 locally progressive clinical prostate cancer specimens obtained by transurethral resection of the prostate, utilizing a variety of complementary technical approaches. The methods to detect PTEN deletion included allelotype analysis, dual-colour FISH and array-based CGH. We also applied a novel semi-quantitative approach, assessing the PTEN-WT (wild-type): PTEN-Psi (pseudogene) ratio (WPR). Structural analysis of PTEN was performed by single-strand conformational polymorphism (PCR-SSCP) and sequencing. PTEN protein expression was assessed by immunohistochemistry. Our data predict complete PTEN inactivation in 12 samples (30%), nine of these by bi-allelic deletion. Loss of one PTEN copy was also detected by several methodologies but the number could not be accurately assessed. Immunohistochemistry indicated the absence of PTEN protein in 15 samples, and heterogeneous expression of the protein in eight tumours. Taken together, these data show that bi-allelic deletion is a major mechanism of PTEN inactivation in locally progressive prostate cancer.

Chromosomes, Human, Pair 10↗
PubMed2005

Differentiation and development of human female germ cells during prenatal gonadogenesis: an immunohistochemical study.

BACKGROUND: In the development of the human ovary, the second trimester includes the transition from oogonial replication to primordial follicle formation. The present study was carried out to assess differentiation and proliferation of germ cells in a series of female gonads from 19 fetuses from the second and third trimester, and two neonates. METHODS: Using immunohistochemistry, the following markers were studied: placental/germ-like cell alkaline phosphatases (PLAP), the marker of pluripotency OCT3/4, the proliferation marker Ki-67, beta-catenin and E-cadherin, the stem cell factor receptor c-KIT, and VASA, a protein specific for the germ cell lineage. RESULTS: PLAP and OCT3/4 were seen during oogenesis, but not in germ cells engaged in folliculogenesis. A similar pattern was observed for Ki-67. Loss of pluripotency occurs once oocytes engage in follicle formation, suggesting a role of cell-cell interactions in the process of germ cell maturation. VASA, c-KIT, beta-catenin and E-cadherin were found in germ cells at all developmental stages of oogenesis and folliculogenesis. CONCLUSIONS: Immunohistochemically, two groups of germ cells can be distinguished. Germ cells that are predominantly found in the cortical region of the ovary before weeks 22-24 of gestation, showing an immature phenotype, are mitotically active, and express OCT3/4, a marker of pluripotency. On the other hand, germ cells undergoing folliculogenesis have lost their pluripotent potential and no longer proliferate.

Alkaline Phosphatase↗
PubMed2004

Raman spectroscopic analysis identifies testicular microlithiasis as intratubular hydroxyapatite.

PURPOSE: As diagnosed by ultrasonography, testicular microlithiasis is associated with various benign and malignant conditions. The molecular constitution of these microliths is largely unknown. Raman spectroscopy provides detailed in situ information about the molecular composition of tissues and to our knowledge it has not been applied to gonadal microliths. We analyzed the molecular composition of gonadal microlithiasis and its surrounding region using Raman spectroscopy in malignant and benign conditions. MATERIALS AND METHODS: Multiple microliths from 6 independent samples diagnosed with gonadal microlithiasis by ultrasound and histologically confirmed were investigated by Raman spectroscopy. The samples included 4 testicular parenchyma samples adjacent to a germ cell tumor (4 seminomas), a gonadoblastoma of a dysgenetic gonad and testicular biopsy of a subfertile male without malignancy. RESULTS: Raman spectroscopic mapping demonstrated that testicular microliths were located within the seminiferous tubule. Glycogen surrounded all microliths in the samples associated with germ cell neoplasm but not in the benign case. The molecular composition of the 26 microliths in all 6 conditions was pure hydroxyapatite. CONCLUSIONS: Microliths in the testis are located in the seminiferous tubules and composed of hydroxyapatite. In cases of germ cell neoplasm they co-localize with glycogen deposits.

Calculi↗
PubMed2003

Morphology of testicular parenchyma adjacent to germ cell tumours. An interim report.

A comparative morphological analysis of parenchyma adjacent to testicular germ cell tumours (TGCT) was performed in a series of 181 orchidectomy specimens: 86 with seminomas (Se), 72 with nonseminomatous germ cell tumours (NS) and 23 with combined tumours (CT, which have a Se and a NS component). The following morphological features were semiquantitatively scored: spermatogenesis (modified Johnsen score); amount of tubular atrophy; amount of carcinoma in situ (CIS); amount of intertubular tissue. Absence and presence was scored for the following features: lymphocytic infiltrate surrounding and invading CIS; intratubular seminoma (ISe); intratubular nonseminoma (INS); microlithiasis; diffuse and nodular hyperplasia of Leydig cells; angioinvasiveness; testicular angiopathy. Using non-parametric statistics these features were correlated with each other and with tumour type, tumour size and age of the patient. Se-patients presented at significantly higher age than NS-patients (36 vs 29 years, p=0.001). The age of patients with CT (32 years) was in between that of Se- and NS-patients. No correlation was found between patient age and tumour size. Parenchyma adjacent to Se, compared to parenchyma adjacent to NS had the following significant differences: a lower Johnsen score (5.6 vs 7.2, p=0.005); less frequent (85% vs 97% of specimens, p=0.016) and a lesser amount of CIS (26% vs 32% of tubules, p=0.015); more frequent peri- (80% vs 60% of specimens, p=0.001) and intratubular (68% vs 30% of specimens, p=0.001) lymphocytic infiltrates; more extensive tubular atrophy (36% vs 15% of tubules, p=0.001); and a larger area of intertubular tissue (42% vs 34% of parenchyma area, p=0.016). The pooled Se and CT had a significantly higher frequency of ISe than the NS (31% vs 17% of specimens, p=0.036). With one exception INS was only found adjacent to NS or CT, with a frequency of 16%, and 20% of the specimens, respectively. It was significantly associated with angio-invasiveness. In specimens lacking angio-invasion the frequency of INS was 6%. The correlation of INS with tumour size and patient age was studied in a series of 145 NS and CT (95 from the original series supplemented by 50 newer cases). In this series INS was significantly associated with smaller tumours and younger patients. Extensive tubular atrophy was significantly correlated with higher age, the diagnosis of Se, a low Johnsen score, and the presence of angiopathy. The more tubular atrophy, the less CIS (both in incidence and amount). Inversely, a higher Johnsen score is associated with smaller tumours, the diagnosis of NS or CT, a higher incidence and a larger amount of CIS, and little tubular atrophy. Tubules with mature spermatogenesis were found in 42% of the specimens regardless of tumour type. We conclude that ISe and INS are probably frequent intermediate stages between CIS and Se and NS, respectively. The features of parenchyma adjacent to Se are probably due to the host response elicited by the invasive Se, which secondarily also affects CIS. The long time to clinical presentation allows the host to eradicate most of the CIS by the time the tumour is surgically removed. The much less extensive morphological features of a host response in parenchyma adjacent to NS support the contention that NS originates as INS, behind the blood/testis barrier, without exposure of the host to tumour cells with a seminomatous phenotype (CIS- or Se cells). Microlithiasis and testicular angiopathy are frequent, but not specific findings in parenchyma next to TGCT. Their relationship with the development with TGCT is unexplained.

Adult↗
PubMed2001

Reactivity of germ cell maturation stage-specific markers in spermatocytic seminoma: diagnostic and etiological implications.

It is generally accepted that testicular seminomas and spermatocytic seminomas have separate pathogeneses, although the origin of these two types of germ cell tumors of the adult testis remains a matter of debate. Although an embryonic germ cell origin seems to be most likely for seminomas, a spermatogonia-spermatocyte origin has been suggested for spermatocytic seminoma. To shed more light on the etiology of spermatocytic seminomas, we undertook an immunohistochemical and molecular approach using SCP1 (synaptonemal complex protein 1), SSX (synovial sarcoma on X chromosome), and XPA (xeroderma pigmentosum type A) as targets. Although a stage-specific expression pattern has been reported for SCP1 and SSX in normal spermatogenesis, we demonstrate here that it also exists for XPA. In fact, immunohistochemistry shows that the proteins of SCP1 and XPA are specifically present in the stage of primary and pachytene spermatocytes. In contrast, SSX was found in spermatogonia and primary spermatocytes, as well as in germ cells, from at least the 17th week of intrauterine development onward. Although no protein encoded by any of these genes was detected in tumor cells of a series of testicular seminomas, all tested spermatocytic seminomas were positive, in agreement with expression analysis. These data support the model that seminomas originate from an embryonic germ cell, and they imply that the cell of origin of spermatocytic seminomas is at least capable of maturing to the stage of spermatogonia-pachytene spermatocyte.

Antibody Specificity↗
PubMed2000

Restricted 12p amplification and RAS mutation in human germ cell tumors of the adult testis.

Human testicular germ-cell tumors of young adults (TGCTs), both seminomas and nonseminomas, are characterized by 12p overrepresentation, mostly as isochromosomes, of which the biological and clinical significance is still unclear. A limited number of TGCTs has been identified with an additional high-level amplification of a restricted region of 12p including the K-RAS proto-oncogene. Here we show that the incidence of these restricted 12p amplifications is approximately 8% in primary TGCTs. Within a single cell formation of i(12p) and restricted 12p amplification is mutually exclusive. The borders of the amplicons cluster in short regions, and the amplicon was never found in the adjacent carcinoma in situ cells. Seminomas with the restricted 12p amplification virtually lacked apoptosis and the tumor cells showed prolonged in vitro survival like seminoma cells with a mutated RAS gene. However, no differences in proliferation index between these different groups of seminomas were found. Although patients with a seminoma containing a homogeneous restricted 12p amplification presented at a significantly younger age than those lacking it, the presence of a restricted 12p amplification/RAS mutation did not predict the stage of the disease at clinical presentation and the treatment response of primary seminomas. In 55 primary and metastatic tumors from 44 different patients who failed cisplatinum-based chemotherapy, the restricted 12p amplification and RAS mutations had the same incidence as in the consecutive series of responding patients. These data support the model that gain of 12p in TGCTs is related to invasive growth. It allows tumor cells, in particular those showing characteristics of early germ cells (ie, the seminoma cells), to survive outside their specific microenvironment. Overexpression of certain genes on 12p probably inhibits apoptosis in these tumor cells. However, the copy numbers of the restricted amplification of 12p and K-RAS mutations do not predict response to therapy and survival of the patients.

Adult↗
PubMed2000

Comparative genomic and in situ hybridization of germ cell tumors of the infantile testis.

Chromosomal information on germ cell tumors of the infantile testis, ie, teratomas and yolk sac tumors, is limited and controversial. We studied two teratomas and four yolk sac tumors using comparative genomic hybridization (CGH) and in situ hybridization. No chromosomal anomalies were found in the teratomas by any of the methods, not even after CGH on microdissected tumor cells. All yolk sac tumors showed aneuploidy, loss of parts of 4q and 6q, and gain of parts of 20q. Underrepresentation of parts of 8q and overrepresentation of parts of 3p, 9q, 12p, 17, 19q, and 22 were detected in most cases. In addition, one recurrent yolk sac tumor after a sacral teratoma was studied, showing a highly similar pattern of imbalances. While CGH demonstrated loss of 1p36 in one testicular yolk sac tumor, in situ hybridization revealed loss of this region in all yolk sac tumors. High-level amplification of the 12q13-q14 region was found in one yolk sac tumor. MDM2, of which the encoding gene maps to this chromosomal region, was found in all cases using immunohistochemistry, whereas no p53 could be detected. Accordingly, no mutations within exons 5 to 8 of the p53 gene were observed. These data prove the absence of gross chromosomal aberrations in teratomas of the infantile testis and show a characteristic pattern of gains and losses in the yolk sac tumors. Besides confirmation of previously found anomalies, recurrent losses of 1p21-31 and 4q23-33 and gains of 9q34 and 12p12-13 have not been reported before. While genetic inactivation of p53 seems unimportant in the pathogenesis of these tumors, biochemical inactivation by MDM2 might be involved. These data support the existence of three entities of germ cell tumors of the human testis: teratomas and yolk sac tumors of infants, seminomas and nonseminomas of adolescents and young adults, and spermatocytic seminomas of the elderly, each with its own specific pathogenesis.

Aneuploidy↗