RESUMO
OBJECTIVE: To analyze the clinical, hormonal, anatomical, and molecular characteristics of Leydig cell tumors, a very rare cause of progressive hyperandrogenism in children. STUDY DESIGN: Description of a 9-year-old boy with isosexual precocious pseudopuberty, and of a 12-year-old girl with rapidly progressive virilization, both due to a pure Leydig cell tumor. Review of all cases of pediatric Leydig cell tumors published since 1999 (when the first somatic mutations of the luteinizing hormone receptor were described) and reporting hormonal and/or molecular data. RESULTS: Boys (n = 24) are younger than girls (n = 12) at diagnosis (median 6.5 vs 13.0 years, P = .04). Plasma gonadotrophins are more often completely suppressed in boys (6 cases) than in girls (2 cases). Pure Leydig cell tumors are exceedingly rare in girls (2 cases), who most often have Sertoli-Leydig tumors. These tumors affect either testis equally (11 left, 13 right) but occur more often in the left ovary (8 left, 3 right). Activating mutations of the alpha-subunit of the G(s) stimulatory protein have not been found in either boys or girls and activating mutations of the luteinizing hormone receptor have only been found in boys. CONCLUSIONS: Leydig cell tumors in children display clinical, hormonal, anatomical, and molecular sexual dimorphism.
Assuntos
Tumor de Células de Leydig/diagnóstico , Neoplasias Ovarianas/diagnóstico , Neoplasias Testiculares/diagnóstico , Biomarcadores/sangue , Criança , Feminino , Marcadores Genéticos , Gonadotropinas/sangue , Humanos , Tumor de Células de Leydig/sangue , Tumor de Células de Leydig/genética , Masculino , Neoplasias Ovarianas/sangue , Neoplasias Ovarianas/genética , Fenótipo , Fatores Sexuais , Neoplasias Testiculares/sangue , Neoplasias Testiculares/genéticaRESUMO
The studies presented herein were designed to investigate the effect of mouse epidermal growth factor (mEGF) on arachidonic acid (AA) release in a clonal strain of cultured murine Leydig cells (designed MA-10). In MA-10 cells, mEGF promotes AA release and metabolism to lipoxygenated products to induce the steroidogenic acute regulatory (StAR) protein. However, the mechanism by which mEGF releases AA in these cells is not totally elucidated. We show that mEGF produces an increment in the mitochondrial AA content in a short-term incubation (30 min). This AA is released by the action of a mitochondrial acyl-CoA thioesterase (Acot2), as demonstrated in experiments in which Acot2 was down or overexpressed. This AA in turn regulates the StAR protein expression, indirect evidence of its metabolism to lipoxygenated products. We also show that mEGF induces the expression (mRNA and protein) of Acot2 and an acyl-CoA synthetase that provides the substrate, arachidonyl-CoA, to Acot2. This effect is also observed in another steroidogenic cell line, the adrenocortical Y1 cells. Taken together, our results show that: 1) mEGF can induce the generation of AA in a specific compartment of the cells, i.e. the mitochondria; 2) mEGF can up-regulate acyl-CoA synthetase and Acot2 mRNA and protein levels; and 3) mEGF-stimulated intramitochondrial AA release leads to StAR protein induction.
Assuntos
Fator de Crescimento Epidérmico/farmacologia , Células Intersticiais do Testículo/efeitos dos fármacos , Animais , Ácido Araquidônico/metabolismo , Western Blotting , Linhagem Celular Tumoral , Células Cultivadas , Células Clonais , Coenzima A Ligases/genética , Coenzima A Ligases/metabolismo , Tumor de Células de Leydig/genética , Tumor de Células de Leydig/metabolismo , Tumor de Células de Leydig/patologia , Células Intersticiais do Testículo/citologia , Células Intersticiais do Testículo/metabolismo , Masculino , Mitocôndrias/efeitos dos fármacos , Mitocôndrias/metabolismo , Fosfoproteínas/metabolismo , Ratos , Reação em Cadeia da Polimerase Via Transcriptase Reversa , Tioléster Hidrolases/genética , Tioléster Hidrolases/metabolismoRESUMO
Activating mutations of the G protein genes have been associated with the development of several endocrine neoplasms. Such activating mutations, gip2, affecting the alpha-subunit of the G alpha i2 protein were previously described by a single group in 30% of ovarian sex cord stromal tumors. Other activating mutations of the alpha-subunit of the Gs (gsp) have been identified in GH-secreting and nonfunctioning pituitary tumors, autonomous thyroid adenomas, and all affected McCune-Albright tissues, but not in sex cord stromal tumors. In the present study, we investigated the presence of gip2 and gsp mutations in 14 human sex cord stromal tumors. Six Leydig cell tumors (4 ovaries and 2 testes), 2 thecomas, 2 granulosa cell tumors, 3 androblastomas, and 1 gonadoblastoma (sex cord and germ cell) were included in this study. Genomic DNA was obtained from either fresh-frozen tumor tissues or paraffin-embedded sections and in some cases from blood samples. Using PCR, denaturing gradient gel electrophoresis, and direct sequencing, we detected 4 tumors (66.6%) with the gsp mutation (R201C) in our series of ovarian and testicular Leydig cell tumors. In contrast, no gip2 mutations were found in any of the sex cord stromal tumors studied. In conclusion, our findings suggest that the putative oncogene gsp may play a significant role in the molecular mechanism of these tumors.