N. Chevalier

GPR30, the Non-Classical Membrane G Protein Related Estrogen Receptor, Is Overexpressed in Human Seminoma and Promotes Seminoma Cell Proliferation

Background Testicular germ cell tumours are the most frequent cancer of young men with an increasing incidence all over the world. Pathogenesis and reasons of this increase remain unknown but epidemiological and clinical data have suggested that fetal exposure to environmental endocrine disruptors (EEDs) with estrogenic effects, could participate to testicular germ cell carcinogenesis. However, these EEDs (like bisphenol A) are often weak ligands for classical nuclear estrogen receptors. Several research groups recently showed that the non classical membrane G-protein coupled estrogen receptor (GPER/GPR30) mediates the effects of estrogens and several xenoestrogens through rapid non genomic activation of signal transduction pathways in various human estrogen dependent cancer cells (breast, ovary, endometrium). The aim of this study was to demonstrate that GPER was overexpressed in testicular tumours and was able to trigger JKT-1 seminoma cell proliferation. Results We report here for the first time a complete morphological and functional characterization of GPER in normal and malignant human testicular germ cells. In normal adult human testes, GPER was expressed by somatic (Sertoli cells) and germ cells (spermatogonia and spermatocytes). GPER was exclusively overexpressed in seminomas, the most frequent testicular germ cell cancer, localized at the cell membrane and triggered a proliferative effect on JKT-1 cells in vitro, which was completely abolished by G15 (a GPER selective antagonist) and by siRNA invalidation. Conclusion These results demonstrate that GPER is expressed by human normal adult testicular germ cells, specifically overexpressed in seminoma tumours and able to trigger seminoma cell proliferation in vitro. It should therefore be considered rather than classical ERs when xeno-estrogens or other endocrine disruptors are assessed in testicular germ cell cancers. It may also represent a prognosis marker and/or a therapeutic target for seminomas.

Bisphenol A promotes testicular seminoma cell proliferation through GPER/GPR30

Dear Sir, Testicular germ cell tumors (TGCT) are the most frequent cancer affecting young men with an increasing incidence all over the world. Pathogenesis and reasons of this increase remain unknown. Epidemiological, clinical and molecular data have suggested that fetal exposure to environmental endocrine disruptors with estrogenic effects could participate in testicular germ cell carcinogenesis by influencing the fate of germ stem cells that share molecular markers with the malignant germ cells. However, no animal model supports this hypothesis, and even estrogen dependency of TGCT has not yet been fully demonstrated. Using the JKT-1 cell line derived from a human testicular seminoma and seminoma tumors, the most frequent TGCTs, we have previously reported that seminoma cells expressed functional aromatase, which is able to convert testosterone into estradiol as well as estrogen receptor beta (ERb) but not ERa. Estradiol 17b (E2) at physiological concentrations was able to suppress in vitro JKT-1 cell proliferation through ERb. However, when E2 was conjugated to bovine serum albumin (E2-BSA), which does not cross the membrane, the effect observed was completely different. E2BSA was able to stimulate JKT-1 cell proliferation by activating the PKA pathway with a rapid (15 min) phosphorylation of the transcription factor cAMP response element binding protein (CREB), through a membrane G-protein-coupled receptor (GPCR). Similar results were obtained with bisphenol A (BPA) at low (pM to nM) concentrations. BPA, a well-recognized estrogenic endocrine disruptor, is used as the monomer to manufacture polycarbonate plastic, and it is released from resin lining of canned foods or beverages or from dental sealants. It is believed to be involved in developmental, reproductive and malignant diseases by mimicking the natural hormone E2 and interfering with

Statut iodé et fonction thyroïdienne chez 330 femmes de la région niçoise évaluées en deuxième partie de grossesse

BACKGROUND Iodine deficiency (ID) is still common in Western Europe and its prevention remains a challenge, particularly during pregnancy. METHODS We studied 330 pregnant women in the third trimester of pregnancy for ioduria (UIE) and thyroid tests (TSH, fT4). We collected information on personal history of thyroid disease and treatment with thyroid hormones or iodinated pregnancy tablets. RESULTS AND DISCUSSION Median UIE was 64 microg/l, reflecting inadequate iodine intake in our population. According to the UIE threshold used for diagnosis (100 to 150 microg/l), ID was present in 74.3% to 85.8% of women; 5.4% had excessive iodine intake, including one taking iodine fortified tablets. Only 8.8% had adequate intake, suggesting that current strategies to eradicate ID are inefficient in our country. Among the 22 women taking iodine supplements, only three had adequate UIE and four had UIE below the detection level, which could suggest either poor compliance or insufficient supplementation. Median fT4 was 12.3pmol/l (8-20.1) and TSH 1.93mUI/l (0.24-6.57). We used different thresholds proposed in the literature to diagnose: hypothyroxinemia: 41.2% were less than 12pmol/l, 10% less than 10.3pmol/l and 1.8% less than 9pmol/l (lower limit of our reference range); subclinical hypothyroidism: 26.3% had TSH greater than 2.5 or 3.9% greater than 4mUI/L, 1.2 to 13% had combined low fT4 (<9pmol/l or <12pmol/) and higher TSH (>2.5mUI/l). There was no correlation between UIE and thyroid tests, nor maternal predicting factors for ID. CONCLUSION ID is common in our population. The wide range of hypothyroxinemia and subclinical hypothyroidism prevalence should also trigger reflection of diagnostic thresholds and therapeutic intervention.

Genetic Variants of GPER/GPR30, a Novel Estrogen-Related G Protein Receptor, Are Associated with Human Seminoma

Testicular germ cell tumors (TGCTs) are the most common solid cancers in young men, with an increasing incidence over several years. However, their pathogenesis remains a matter of debate. Some epidemiological data suggest the involvement of both environmental and genetic factors. We reported two distinct effects of estrogens and/or xeno-estrogens on in vitro human seminoma-derived cells proliferation: (1) an antiproliferative effect via a classical estrogen receptor beta-dependent pathway, and (2) a promotive effect via a non-classical membrane G-protein-coupled receptor, GPR30/GPER, which is only overexpressed in seminomas, the most common TGCT. In order to explain this overexpression, we investigated the possible association of polymorphisms in the GPER gene by using allele-specific tetra-primer polymerase chain reaction performed on tissue samples from 150 paraffin-embedded TGCT specimens (131 seminomas, 19 non seminomas). Compared to control population, loss of homozygous ancestral genotype GG in two polymorphisms located in the promoter region of GPER (rs3808350 and rs3808351) was more frequent in seminomas but not in non-seminomas (respectively, OR = 1.960 (1.172–3.277) and 7.000 (2.747–17.840); p < 0.01). These polymorphisms may explain GPER overexpression and represent a genetic factor of susceptibility supporting the contribution of environmental GPER ligands in testicular carcinogenesis.