The intra-tissue level of thyroid hormones (THs) regulates organ functions. Environmental factors can impair it by damaging the thyroid gland and/or the peripheral TH metabolism. We investigated the effects of embryonic and/or long-life exposure to low-dose pesticides, ethylenethiourea (ETU), chlorpyrifos (CPF) and their mixture, on the intra-tissue T4/T3 metabolism/signalling in zebrafish at different life stages. Hypothyroidism was evidenced in exposed larvae that showed reduced number of follicle and induced tshb mRNAs. Despite that, we evidenced the increase of free T4 (fT4) and free T3 (fT3) levels/signalling that was confirmed by the transcriptional regulation of TH metabolic enzymes (deiodinases) and T3-regulated mRNAs (cpt1, igfbp1a). The second-generation larvae showed effects on thyroid and TH signalling even when not directly exposed, suggesting a role of the parental exposure. In adult zebrafish we found a sex-dependent damage of hepatic T3 level/signalling associated to liver steatosis, more pronounced in female, with a sex-dependent alteration of transcripts codifying the key enzymes involved in “de novo lipogenesis” and of β- oxidation. We found an impaired activation of liver T3 and PPARα/Foxo3a pathways whose deregulation was already involved in mammalian liver steatosis. The data underscore the intra-tissue imbalance of T3 level as a target of thyroid endocrine disruptors (THDC) and suggest that the effects of slight modification of T3 signalling might be amplified by its direct regulation or crosstalk with PPAR/Foxo3a pathways. Because T3 levels define the hypothyroid/hyperthyroid status of each organ, our findings might explain the pleiotropic and site-dependent effects of pesticides.

Thyroid hormones (THs) regulate many biological processes in vertebrates, including reproduction. Testicular somatic and germ cells are equipped with the arrays of enzymes (deiodinases), transporters, and receptors necessary to locally maintain the optimal level of THs and their signalling, needed for their functions and spermatogenesis. Pesticides, as chlorpyrifos (CPF) and ethylene thiourea (ETU), impair the function of thyroid and testis, affecting male fertility. However, their ability to disarrange testicular T3 (t-T3) metabolism and signalling is poorly considered. Here, a multi-species analysis involving zebrafish and mouse suggests the damage of t-T3 metabolism and signalling as a mechanism of gonadic toxicity of low-doses CPF and ETU. Indeed, the developmental exposure to both compounds reduces Dio2 transcript in both models, as well as in ex-vivo cultures of murine seminiferous tubules, and it is linked to alteration of steroidogenesis and germ cell differentiation. A major impact on spermatogonia was confirmed molecularly by the expression of their markers and morphologically evidenced in zebrafish. The results reveal that in the adopted models, exposure to both pesticides alters the t-T3 metabolism and signalling, affecting the reproductive capability. Our data, together with previous reports suggest zebrafish as an evaluable model in assessing the action of compounds impairing locally T3 signalling.

Although the imbalance of circulating levels of Thyroid Hormones (THs) affects female fertility in vertebrates, its involvement in the promotion of Premature Ovarian Aging (POA) is debated. Therefore, altered synthesis of THs in both thyroid and ovary can be a trait of POA. We investigated the relationship between abnormal TH signaling, dysthyroidism, and POA in evolutionary distant vertebrates: from zebrafish to humans. Ovarian T3 signaling/metabolism was evaluated by measuring T3 levels, T3 responsive transcript, and protein levels along with transcripts governing T3 availability (deiodinases) and signaling (TH receptors) in distinct models of POA depending on genetic background and environmental exposures (e.g., diets, pesticides). Expression levels of well-known (Amh, Gdf9, and Inhibins) and novel (miR143/145 and Gas5) biomarkers of POA were assessed. Ovarian dysthyroidism was slightly influenced by genetics since very few differences were found between C57BL/6J and FVB/NJ females. However, diets exacerbated it in a strain-dependent manner. Similar findings were observed in zebrafish and mouse models of POA induced by developmental and long-life exposure to low-dose chlorpyrifos (CPF). Lastly, the T3 decrease in follicular fluids from women affected by diminished ovarian reserve, as well as of the transcripts modulating T3 signaling/availability in the cumulus cells, confirmed ovarian dysthyroidism as a common and evolutionary conserved trait of POA.

Mesothelioma, sometimes referred to as asbestos cancer, is known to be among the most aggressive and difficult to treat tumours. The disease attacks the mesothelium, a protective two-layered membrane that covers the internal organs of the body including the lungs, heart and abdominal organs. Mesothelioma can affect any of these layers, but is usually seen in the pleural (lung) or peritoneal (abdomen) mesothelium. The most commonly diagnosed form of this cancer is pleural mesothelioma, caused primarily by the inhalation of asbestos fibers. The prevalence of this cancer is estimated at less than 1% of all cancers, however its incidence is increasing, with an expected peak in the next 10-20 years. Mesotheliomas are tumours that have a poor prognosis due to limited treatment options. The most aggressive form is the sarcomatoid histotype, followed by the biphasic and the epithelioid histotypes.In order to setup in vivo models of human mesothelioma, translational related to human pathology in terms of histology, antigen expression and pharmacological response to therapy, we have established three mesothelioma in vivo models using primary cells derived from patients having different mesothelioma histotypes.We stably transfected MM-432 (sarcomatoid), MM-473 (epithelioid) and MM-487 (biphasic) mesothelioma cell lines with a luciferase expression vector. The selected high luc-espressing clones were inoculated intrapleurally in immunodeficient nude mice, and they successfully invaded and proliferated within the murine host. In particular, the epithelioid histotype presented tumour growth 100% of the time, after a short latency period. The biphasic histotype failed to present tumour growth in 30% of the cases, however was far more aggressive than the epithelial histotype upon establishment of tumour growth. Moreover, the ex-vivo Immunocytochemistry (i.e for CEA, EMA, Mesothelin, Podoplanin, calretinin) and biochemical characterization (i.e.EGFR, VEGF, Top1, TKs pathways) of the three histotypes, revealed histotype-related differences. Finally, the cytotoxic responses to a panel of antitumor drugs (i.e . Doxorubicin , Topotecan , Ciclofosfamide, Dacarbazina, Gemcitabine, Temozolomide, Bortezomib, 5-azacitidina, Paclitaxel, Etoposide, 5-FU, Cisplatin, and AZD-2281) revealed that the three original cell lines, compared to the corresponding luc-expressing clones, had similar sensitivities to drugs depending upon the tumor histotypes. Further, in vivo characterizations focused on chemotherapeutic responses of these models, are currently in progress. Citation Format: Claudio Pisano, Alison G. Cole, Marcella Barbarino, Erminia Bianchino, Mario Guglielmi, Carmela Melito, Grazia Mercadante, Alfonsina Porciello, Assunta Riccio, Ilaria La Porta, Sara Orecchia, Roberta Libener, Laura Mazzucco, Simonetta Andrea Licandro, Pasquale De Luca. Mice models of three human mesothelioma histotypes derived from primary patient tumors. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 5556. doi:10.1158/1538-7445.AM2014-5556

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