668

FOXL2

BPES|BPES1|PFRK|PINTO|POF3;forkhead box L2;FOXL2;forkhead box L2

forkhead box protein L2|forkhead transcription factor FOXL2

3q23

protein-coding

PURPOSE: FOXL2 is the earliest known marker of ovarian differentiation in mammals. It is involved in ovarian somatic cell differentiation and further follicle maintenance. FOXL2 is not implicated in determination of the male gonadand it is absent in the testis. We investigated whether the rare JGCTT (juvenilegranulose cell tumor of the testis), named for its histological similarity to ovarian tumor, could be the first illustration of aberrant expression of this ovary determining gene in the human testis. MATERIALS AND METHODS: Between 1990 and 2004, 3 boys with JGCTT were reported from the TGM95 database of the French Society for childhood cancer and from 8 pediatric endocrinology centers. Orchiectomy was performed in these patients. Immunohistochemistry of FOXL2, and co-immunofluorescence of FOXL2 and SOX9 were performed on tumor sections. RESULTS: Testicular tumor cells showed aberrant expression of FOXL2, which resembled normal ovarian granulosa cells. The localization of FOXL2 expression was nuclear without any cytoplasmic sequestration, suggesting that FOXL2 had biological activity. Conversely SOX9, which is present in the nucleus of normal testicular cells, was sequestered in the cytoplasm of granulosa tumor cells or markedly under expressed in the nuclei. In this case of residual SOX9 nuclear expression the expression of FOXL2 and SOX9 was mutually exclusive. CONCLUSIONS:To our knowledge we report the first human model of aberrant intratesticular expression of an ovary determining gene along with the extinction of SOX9 and the transdifferentiation of a testicular cell into a granulosa tumor cell.

Ovarian sex cord-stromal tumors are rare tumors that originate from the nongerminal cells of ovary. Two decades ago, the identification of juvenile granulosa-cell tumors (GCT), as a specific entity inside this group, allowed a better treatment of these tumors in children. However, little data have been reported on the natural course of the disease and reliable prognostic factors have not been yet defined. We here review the clinical and genetics aspects of granulosa tumors, based on a series of 40 children. This national collaborative study involved the French Society of children cancer and eight clinical departments of pediatric endocrinology. We found that early diagnosis of a tumor, revealed by clinical signs of hyperoestrogeny, is an important prognostic factor. The pathophysiology of these tumors is still debatable and several cellular- andmolecular-abnormal signals could be implicated in their development. The role ofgrowth factors and oncogenes through the signaling pathway of MAP kinase is still discussed. According to our data, FSH signaling-transduction pathway, such as a constitutionally activated Galphas, could also be implicated in the induction ofgranulosa cell proliferation and seems to modulate the invasiveness of the tumor. Last, we have described a low-expression pattern or an extinction of an ovarian-determination gene, FOXL2, which is related to a worse prognosis of thistumor.