Characterization of the model for experimental testicular teratoma in 129/SvJ-mice

An animal model of experimental testicular teratoma has been established to study how a teratoma affects the host testis and how the host testis reacts against the teratoma. 129/SvJ-mice were used as experimental animals. To induce the experimental testicular teratoma, male gonadal ridges from 12-day-old 129/SvJ-mouse fetuses were grafted into the testes of adult mice for 1-12 weeks. The developing tumour was analysed by light and electron microscopy and by immunocytochemical localization of transcription factors SOX9 and c-kit, glial fibrillary acidic protein (GFAP) and type IV collagen. Testicular teratoma was observed in 36 out of 124 testes with implanted fetal gonadal ridges (frequency 29%). One spontaneous testicular teratoma was observed in this material from 70 male mice (1.5%). One week after implantation intracordal clusters of cells were seen in embryonic testicular cords of the graft as the first sign of testicular teratomas. Four weeks after implantation the embryonic testicular cords had totally disappeared from grafts with teratomas, and the tumour tissue had enlarged the testis and invaded the interstitium of the host testis. It consisted of solitary pieces of immature cartilage as well as of glial cells and of primitive neuroepithelium. Six to eight weeks after implantation the tumour tissue had expanded so that the enlarged testis could be detected by macroscopic enlargement of the scrotum. The testicular tissue of the host had practically disappeared, and only solitary disrupted seminiferous tubules of the host were seen surrounding the teratoma. Neuroepithelial structures of some teratomas cultured for 8 weeks had cells with a granular nucleus as a sign of obvious apoptosis. Eleven to 12 weeks after implantation the growth of the teratoma had stopped, and the histology corresponded to that of a mature cystic teratoma. GFAP, SOX9 and type IV collagen were strongly positive in some parts of the tumours cultured for 4 and 8 weeks, while only occasional c-kit-positive areas were observed in tumours cultured for 8 weeks. As conclusions: (1) the metastasizing capacity of the experimental testicular teratoma is very low during 12 weeks, but the behaviour of the tumour in the testicular tissue of the graft is invasive; (2) the growth of experimental testicular teratomas cease 6-8 weeks after implantation of the fetal gonadal ridges with the obvious apoptosis of the immature tissue components; (3) the model of experimental testicular teratoma in the mouse is suitable for studying how the teratoma affects the host testis and how the host testis reacts to teratoma

Microsatellite Instability, Mismatch Repair Deficiency, and BRAF Mutation in Treatment-Resistant Germ Cell Tumors

Purpose Mismatch repair (MMR) deficiency and microsatellite instability (MSI) are associated with cisplatin resistance in human germ cell tumors (GCTs). BRAF mutation (V600E) is found in MSI colorectal cancers. The role of RAS/RAF pathway mutations in GCT treatment response is unknown. Patients and Methods Two patient cohorts were investigated: 100 control GCTs (50 seminomas and 50 nonseminomas) and 35 cisplatin-based chemotherapy-resistant GCTs. MMR proteins were analyzed by immunohistochemistry, and eight microsatellite loci were examined for MSI. Tumors were assessed for specific BRAF and KRAS mutations. Results Resistant tumors showed a higher incidence of MSI than controls: 26% versus 0% in two or more loci (P<.0001). All resistant tumors were wild-type KRAS, and two controls (2%) contained a KRAS mutation. There was a significantly higher incidence of BRAF V600E mutation in resistant tumors compared with controls: 26% versus 1% (P<.0001). BRAF mutations were highly correlated with MSI (P=.006), and MSI and mutated BRAF were correlated with weak or absent staining for hMLH1 (P=.017 and P=.008). Low or absent staining of hMLH1 was correlated with promoter hypermethylation (P<.001). Tumors lacking expression of hMLH1 or MSH6 were significantly more frequent in resistant GCTs than in controls (P=.001 and 0.0036, respectively). Within the subgroup of resistant tumors, patients with MSI showed a trend to longer progression-free survival (P=.068). Conclusion We report for the first time a correlation between a gene mutation-BRAF V600E-and cisplatin resistance in nonseminomatous GCTs. Furthermore, a correlation between MMR deficiency, MSI, and treatment failure is confirmed

Testicular cancer: biology and biomarkers

The term "human germ cell tumors" (GCTs) refers to a heterogeneous group of neoplasms, all with a defined histological appearance. They have specific epidemiological characteristics, clinical behavior, and pathogenesis. Histologically, GCTs contain various tissue elements, which are homologs of normal embryogenesis. We have proposed a subclassification of GCTs in five subtypes, three of which preferentially occur in the testis. These include teratomas and yolk sac tumors of neonates and infants (type I), seminomas and nonseminomas of (predominantly) adolescents and adults (type II), and spermatocytic seminomas of the elderly (type III). Both spontaneous and induced animal models have been reported, of which the relevance for human GCTs is still to be clarified. Multidisciplinary studies have recently shed new light on the (earliest steps in the) pathogenesis of GCTs, mainly in regard of malignant type II GCTs (germ cell cancer (GCC)). This review discusses novel understanding of the pathogenesis of (mainly) GCC, focusing on identification of informative diagnostic markers suitable for application in a clinical setting. These include OCT3/4, SOX9/FOXL2, SOX17/SOX2, as well as embryonic microRNAs. These markers have been identified through studies on normal embryogenesis, specifically related to the gonads, including the germ cell lineage. Their strengths and limitations are discussed as well as the expected future approach to identify the group of individuals at highest risk for development of a GCC. The latter would allow screening of defined populations, early diagnosis, optimal follow-up, and potentially early treatment, preventing long-term side effects of systemic treatment