http://repub.eur.nl/res/aut/6007/ List of Publications en http://repub.eur.nl/static-eur/img/logo.png http://repub.eur.nl http://repub.eur.nl/res/pub/10129/ 2003-01-01T00:00:00Z Human germ cell tumors (GCTs) may have variable histology and clinical behavior, depending on factors such as sex of the patient, age at clinical diagnosis, and anatomical site of the tumor. Some types of GCT, i.e., the seminomas/germinomas/dysgerminomas and embryonal carcinomas (the stem cell component of nonseminomas), have pluripotent potential, which is demonstrated by their capacity to differentiate into somatic and/or extraembryonic elements. Although embryonal carcinoma cells are intrinsically pluripotent, seminoma/germinoma/dysgerminoma cells, as well as their precursor carcinoma in situ/gonadoblastoma cells, have the phenotype of early germ cells that can be activated to pluripotency. The other types of GCT (teratomas and yolk sac tumors of infants and newborn, dermoid cyst of the ovary, and spermatocytic seminoma of elderly) are composed of (fully) differentiated tissues and lack the appearance of undifferentiated and pluripotent stem cells. OCT3/4, a transcription factor also known as OTF3 and POU5F1, is involved in regulation of pluripotency during normal development and is detectable in embryonic stem and germ cells. We analyzed the presence of POU5F1 in GCT and other tumor types using immunohistochemistry. The protein was consistently detected in carcinoma in situ/gonadoblastoma, seminomas/germinoma/dysgerminoma, and embryonal carcinoma but not in the various types of differentiated nonseminomas. Multitumor tissue microarray analysis covering >100 different tumor categories and 3600 individual cancers verified that POU5F1 expression is specific for particular subtypes of GCT of adults. No protein was observed in GCT of newborn and infants, spermatocytic seminomas, and the various tumors of nongerm cell origin. In addition, no difference in staining pattern was found in chemosensitive and chemoresistant GCT of adults. These results indicate preservation of the link between POU5F1 and pluripotency, as reported during normal development, after malignant transformation. Therefore, POU5F1 immunohistochemistry is an informative diagnostic tool for pluripotent GCT and offers new insights into the histological heterogeneity of this cancer. http://repub.eur.nl/res/pub/10242/ 2003-01-01T00:00:00Z Testicular germ-cell tumors (TGCTs) of adolescents and adults originate from intratubular germ cell neoplasia (ITGCN), which is composed of the malignant counterparts of embryonal germ cells. ITGCN cells are characterized, among others, by the presence of stem cell factor receptor c-KIT. Once established, ITGCN will always progress to invasiveness. Approximately 2.5-5% of patients with a TGCT will develop bilateral disease and require complete castration, resulting in infertility, a need for lifelong androgen replacement, and psychological stress. To date, the only way to predict a contralateral tumor is surgical biopsy of the contralateral testis to demonstrate ITGCN. We did a retrospective study of 224 unilateral and 61 proven bilateral TGCTs (from 46 patients, in three independently collected series in Europe) for the presence of activating c-KIT codon 816 mutations. A c-KIT codon 816 mutation was found in three unilateral TGCT (1.3%), and in 57 bilateral TGCTs (93%; P < 0.0001). In the two wild-type bilateral tumors for which ITGCN was available, the preinvasive cells contained the mutation. The mutations were somatic in origin and identical in both tumors. We conclude that somatic activating codon 816 c-KIT mutations are associated with development of bilateral TGCT. Detection of c-KIT codon 816 mutations in unilateral TGCT identifies patients at risk for bilateral disease. These patients may undergo tailored treatment to prevent the development of bilateral disease, with retention of testicular hormonal function.