RESUMO
The patient's hormonal context plays a crucial role in the outcome of cancer. However, the association between thyroid disease and breast cancer risk remains unclear. We evaluated the effect of thyroid status on breast cancer growth and dissemination in an immunocompetent mouse model. For this, hyperthyroid and hypothyroid Balb/c mice were orthotopically inoculated with triple-negative breast cancer 4T1 cells. Tumors from hyperthyroid mice showed an increased growth rate and an immunosuppressive tumor microenvironment, characterized by increased IL-10 levels and decreased percentage of activated cytotoxic T cells. On the other hand, delayed tumor growth in hypothyroid animals was associated with increased tumor infiltration of activated CD8+ cells and a high IFNγ/IL-10 ratio. Paradoxically, hypothyroid mice developed a higher number of lung metastasis than hyperthyroid animals. This was related to an increased secretion of tumor CCL2 and an immunosuppressive systemic environment, with increased proportion of regulatory T cells and IL-10 levels in spleens. A lower number of lung metastasis in hyperthyroid mice was related to the reduced presence of mesenchymal stem cells in tumors and metastatic sites. These animals also exhibited decreased percentages of regulatory T lymphocytes and myeloid-derived suppressor cells in spleens but increased activated CD8+ cells and the IFNγ/IL-10 ratio. Therefore, thyroid hormones modulate the cellular and cytokine content of the breast tumor microenvironment. A better understanding of the mechanisms involved in these effects could be a starting point for the discovery of new therapeutic targets for breast cancer.
Assuntos
Neoplasias da Mama , Hipertireoidismo , Hipotireoidismo , Neoplasias Pulmonares , Neoplasias de Mama Triplo Negativas , Animais , Neoplasias da Mama/patologia , Linhagem Celular Tumoral , Feminino , Humanos , Interleucina-10/uso terapêutico , Neoplasias Pulmonares/secundário , Camundongos , Camundongos Endogâmicos BALB C , Microambiente TumoralRESUMO
Thyroid hormones (THs) - 3,3',5-triiodo-L-thyronine (T3) and L-thyroxine (T4) - are important regulators of the metabolism and physiology of most normal tissues. Cytochrome P450 family 3A members are drug metabolizing enzymes involved in the activation and detoxification of several drugs. CYP3A4 is the major enzyme involved in the metabolism of chemotherapeutic drugs. In this work, we demonstrate that THs induce a significant increase in CYP3A4 mRNA levels, protein expression and metabolic activity through the membrane receptor integrin αvß3 and the activation of signalling pathways through Stat1 and NF-κB. We reasoned that TH-induced CYP3A4 modulation may act as an important regulator in the metabolism of doxorubicin (Doxo). Experiments in vitro demonstrated that in CYP3A4-knocked down cells, no TH-mediated chemosensitivity to Doxo was observed. We also found that THs modulate these functions by activating the membrane receptor integrin αvß3. In addition, we showed that the thyroid status can modulate CYP450 mRNA levels in tumor and liver tissues, and the tumor volume in response to chemotherapy in vivo. In fact, Doxo treatment in hypothyroid mice was associated with lower tumors, displaying lower levels of CYP enzymes, than euthyroid mice. However, higher mRNA levels of CYP enzymes were found in livers from Doxo treated hypothyroid mice respect to control. These results present a new mechanism by which TH could modulate chemotherapy response. These findings highlight the importance of evaluating thyroid status in patients during application of T-cell lymphoma therapeutic regimens.
RESUMO
Radiotherapy is one of the leading treatments for clinical cancer therapy. External beam radiotherapy has been proposed as an adjuvant treatment for patients bearing differentiated thyroid cancer refractory to conventional therapy. Our purpose was to study the combined effect of HDAC inhibitors (HDACi) and ionizing irradiation in thyroid cancer cell lines (Nthy-ori 3-1, WRO, TPC-1 and 8505c). HDACi radiosensitized thyroid cancer cells as evidenced by the reduction of survival fraction, whereas they had no effect in the normal cells. HDACi enhanced radiation-induced cell death in WRO cells. Gamma-H2AX foci number increased and persisted long after ionizing exposure in the HDACi-treated cells (WRO and TPC-1). Moreover, the expression of the repair-related gene Ku80 was differentially modulated only in the cancer cells, by the compounds at the protein and/or mRNA levels. We present in vitro evidence that HDACi can enhance the radiosensitivity of human thyroid cancer cells.
Assuntos
Ácido Butírico/farmacologia , Inibidores de Histona Desacetilases/farmacologia , Tolerância a Radiação/efeitos dos fármacos , Neoplasias da Glândula Tireoide/patologia , Ácido Valproico/farmacologia , Pontos de Checagem do Ciclo Celular/efeitos dos fármacos , Pontos de Checagem do Ciclo Celular/efeitos da radiação , Morte Celular/efeitos dos fármacos , Morte Celular/efeitos da radiação , Linhagem Celular Tumoral , Dano ao DNA , Enzimas Reparadoras do DNA/genética , Enzimas Reparadoras do DNA/metabolismo , Raios gama , Regulação Neoplásica da Expressão Gênica/efeitos dos fármacos , Regulação Neoplásica da Expressão Gênica/efeitos da radiação , Histonas/metabolismo , Humanos , Tolerância a Radiação/efeitos da radiação , Neoplasias da Glândula Tireoide/genéticaRESUMO
Stat3 is a signaling node for multiple oncogenic pathways and is therefore frequently active in breast cancer. As experimental and clinical evidence reveals that progestins are key players in controlling mammary gland tumorigenesis, we studied Stat3 participation in this event. We have previously shown that progestins induce Stat3Tyr705 phosphorylation and its transcriptional activation in breast cancer cells. In this study, we demonstrate that progestins also induce Stat3 phosphorylation at Ser727 residue, which occurs via activation of c-Src/p42/p44 MAPK pathways in murine progestin-dependent C4HD cells and in T-47D cells. Expression of a Stat3S727A vector, which carries a serine-to-alanine substitution at codon 727, shows that Stat3Ser727 phosphorylation is required for full transcriptional activation of cyclin D1 gene expression by progestins and for in vivo Stat3 recruitment on cyclin D1 promoter. Transfection of Stat3S727A in murine and human breast cancer cells abolished progestin-induced in vitro and in vivo growth. Moreover, we found a positive correlation between progesterone receptor expression and nuclear localization of Stat3Ser727 phosphorylation in breast cancer biopsies. These data highlight Stat3 phosphorylation in Ser727 residue as a nongenomic action by progestins, necessary to promote breast cancer growth.
Assuntos
Acetato de Medroxiprogesterona/farmacologia , Proteína Quinase 1 Ativada por Mitógeno/metabolismo , Proteína Quinase 3 Ativada por Mitógeno/metabolismo , Fator de Transcrição STAT3/metabolismo , Animais , Neoplasias da Mama/metabolismo , Proliferação de Células , Ciclina D1/metabolismo , Feminino , Humanos , Camundongos , Camundongos Endogâmicos BALB C , Fosforilação , Fator de Transcrição STAT3/genéticaRESUMO
Aberrant Stat3 activation and signaling contribute to malignant transformation by promoting cell cycle progression, inhibiting apoptosis, and mediating tumor immune evasion. Stat3 inhibition in tumor cells induces the expression of chemokines and proinflammatory cytokines, so we proposed to apply Stat3-inhibited breast cancer cells as a source of immunogens to induce an antitumor immune response. Studies were performed in two murine breast cancer models in which Stat3 is activated: progestin-dependent C4HD cells and 4T1 cells. We immunized BALB/c mice with irradiated cancer cells previously transfected with a dominant-negative Stat3 vector (Stat3Y705F) in either a prophylactic or a therapeutic manner. Prophylactic administration of breast cancer cells transfected with Stat3Y705F (Stat3Y705F-breast cancer cells) inhibited primary tumor growth compared with administration of empty vector-transfected cells in both models. In the 4T1 model, 50% of the challenged mice were tumor free, and the incidence of metastasis decreased by 90%. In vivo assays of C4HD tumors showed that the antitumor immune response involves the participation of CD4(+) T cells and cytotoxic NK cells. Therapeutic immunization with Stat3Y705F-breast cancer cells inhibited tumor growth, promoted tumor cell differentiation, and decreased metastasis. Furthermore, inhibition of Stat3 activation in breast cancer cells induced cellular senescence, contributing to their immunogenic phenotype. In this work, we provide preclinical proof of concept that ablating Stat3 signaling in breast cancer cells results in an effective immunotherapy against breast cancer growth and metastasis. Moreover, our findings showing that Stat3 inactivation results in induction of a cellular senescence program disclose a potential mechanism for immunotherapy research.
Assuntos
Linfócitos T CD4-Positivos/imunologia , Senescência Celular/imunologia , Marcação de Genes , Células Matadoras Naturais/imunologia , Neoplasias Mamárias Animais/imunologia , Neoplasias Mamárias Animais/terapia , Animais , Linfócitos T CD4-Positivos/metabolismo , Linfócitos T CD4-Positivos/patologia , Linhagem Celular Tumoral , Quimiocinas/metabolismo , Citocinas/metabolismo , Modelos Animais de Doenças , Feminino , Marcação de Genes/métodos , Células Matadoras Naturais/metabolismo , Células Matadoras Naturais/patologia , Neoplasias Mamárias Animais/patologia , Camundongos , Camundongos Endogâmicos BALB C , Camundongos Nus , Cultura Primária de Células , Fator de Transcrição STAT3RESUMO
Progesterone receptor (PR) and ErbB-2 bidirectional cross talk participates in breast cancer development. Here, we identified a new mechanism of the PR and ErbB-2 interaction involving the PR induction of ErbB-2 nuclear translocation and the assembly of a transcriptional complex in which ErbB-2 acts as a coactivator of Stat3. We also highlighted that the function of ErbB-2 as a Stat3 coactivator drives progestin-induced cyclin D1 promoter activation. Notably, PR is also recruited together with Stat3 and ErbB-2 to the cyclin D1 promoter, unraveling a new and unexpected nonclassical PR genomic mechanism. The assembly of the nuclear Stat3/ErbB-2 transcriptional complex plays a key role in the proliferation of breast tumors with functional PR and ErbB-2. Our findings reveal a novel therapeutic intervention for PR- and ErbB-2-positive breast tumors via the specific blockage of ErbB-2 nuclear translocation.
Assuntos
Neoplasias da Mama/etiologia , Neoplasias da Mama/metabolismo , Neoplasias Mamárias Experimentais/etiologia , Neoplasias Mamárias Experimentais/metabolismo , Receptor ErbB-2/metabolismo , Receptores de Progesterona/metabolismo , Fator de Transcrição STAT3/metabolismo , Transativadores/metabolismo , Transporte Ativo do Núcleo Celular/efeitos dos fármacos , Animais , Sequência de Bases , Neoplasias da Mama/genética , Neoplasias da Mama/patologia , Linhagem Celular Tumoral , Proliferação de Células , Feminino , Técnicas de Silenciamento de Genes , Genes bcl-1 , Humanos , Neoplasias Mamárias Experimentais/genética , Neoplasias Mamárias Experimentais/patologia , Acetato de Medroxiprogesterona/toxicidade , Camundongos , Camundongos Endogâmicos BALB C , Progestinas/toxicidade , Regiões Promotoras Genéticas , RNA Interferente Pequeno/genética , Receptor ErbB-2/antagonistas & inibidores , Receptor ErbB-2/genética , Receptores de Progesterona/antagonistas & inibidores , Receptores de Progesterona/genética , Fator de Transcrição STAT3/antagonistas & inibidores , Fator de Transcrição STAT3/genética , Transdução de Sinais , Transcrição Gênica/efeitos dos fármacosRESUMO
Tumor necrosis factor alpha (TNFalpha) is a pleiotropic cytokine which, acting locally, induces tumor growth. Accumulating evidence, including our findings, showed that TNFalpha is mitogenic in breast cancer cells in vitro and in vivo. In the present study, we explored TNFalpha involvement on highly aggressive ErbB-2-overexpressing breast cancer cells. We found that TNFalpha induces ErbB-2 phosphorylation in mouse breast cancer C4HD cells and in the human breast cancer cell lines SK-BR-3 and BT-474. ErbB-2 phosphorylation at Tyr877 residue was mediated by TNFalpha-induced c-Src activation. Moreover, TNFalpha promoted ErbB-2/ErbB-3 heterocomplex formation, Akt activation and NF-kappaB transcriptional activation. Inhibition of ErbB-2 by addition of AG825, an epidermal growth factor receptor/ErbB-2-tyrosine kinase inhibitor, or knockdown of ErbB-2 by RNA interference strategy, blocked TNFalpha-induced NF-kappaB activation and proliferation. However, the humanized monoclonal antibody anti-ErbB-2 Herceptin could not inhibit TNFalpha ability to promote breast cancer growth. Interestingly, our work disclosed that TNFalpha is able to transactivate ErbB-2 and use it as an obligatory downstream signaling molecule in the generation of mitogenic signals. As TNFalpha has been shown to be present in the tumor microenvironment of a significant proportion of human infiltrating breast cancers, our findings would have clinical implication in ErbB-2-positive breast cancer treatment.
Assuntos
Neoplasias da Mama/genética , Genes erbB-2 , NF-kappa B/metabolismo , Proteínas de Neoplasias/biossíntese , Receptor ErbB-2/biossíntese , Receptor ErbB-2/fisiologia , Ativação Transcricional , Fator de Necrose Tumoral alfa/fisiologia , Animais , Neoplasias da Mama/patologia , Divisão Celular , Linhagem Celular Tumoral/efeitos dos fármacos , Linhagem Celular Tumoral/metabolismo , Dimerização , Feminino , Humanos , Neoplasias Mamárias Experimentais/genética , Neoplasias Mamárias Experimentais/metabolismo , Neoplasias Mamárias Experimentais/patologia , Camundongos , Camundongos Endogâmicos BALB C , Invasividade Neoplásica , Proteínas de Neoplasias/genética , Fosforilação , Proteínas Quinases/fisiologia , Processamento de Proteína Pós-Traducional , RNA Interferente Pequeno/farmacologia , Receptor ErbB-2/genética , Transdução de Sinais/efeitos dos fármacos , Transdução de Sinais/genéticaRESUMO
Cross talk between the steroid hormone receptors for estrogen and progesterone (PR) and the ErbB family of receptor tyrosine kinases appears to be a hallmark of breast cancer growth, but its underlying mechanism remains poorly explored. Here we have highlighted signal transducer and activator of transcription 3 (Stat3) as a key protein activated by heregulin (HRG), a ligand of the ErbB receptors, through co-opted, ligand-independent PR function as a signaling molecule. Stat3 activation was an absolute requirement in HRG-induced mammary tumor growth, and targeting Stat3 effectively inhibited growth of breast cancer cells with activated HRG/ErbB-2 and PR. Our findings unravel a novel potential therapeutic intervention in PR- and ErbB-2-positive breast tumors, involving the specific blockage of PR signaling activity.
Assuntos
Proliferação de Células , Neoplasias Mamárias Animais/patologia , Neuregulina-1/metabolismo , Receptor ErbB-2/metabolismo , Receptores de Progesterona/metabolismo , Fator de Transcrição STAT3/metabolismo , Animais , Feminino , Neoplasias Mamárias Animais/etiologia , Camundongos , Camundongos Endogâmicos BALB C , Transdução de SinaisRESUMO
Tumor necrosis factor alpha (TNF alpha) enhances proliferation of chemically-induced mammary tumors and of T47D human cell line through not fully understood pathways. Here, we explored the intracellular signaling pathways triggered by TNF alpha, the participation of TNF alpha receptor (TNFR) 1 and TNFR2 and the molecular mechanism leading to breast cancer growth. We demonstrate that TNFalpha induced proliferation of C4HD murine mammary tumor cells and of T47D cells through the activation of p42/p44 MAPK, JNK, PI3-K/Akt pathways and nuclear factor-kappa B (NF-kappa B) transcriptional activation. A TNF alpha-specific mutein selectively binding to TNFR1 induced p42/p44 MAPK, JNK, Akt activation, NF-kappa B transcriptional activation and cell proliferation, just like wild-type TNF alpha, while a mutein selective for TNFR2 induced only p42/p44 MAPK activation. Interestingly, blockage of TNFR1 or TNFR2 with specific antibodies was enough to impair TNF alpha signaling and biological effect. Moreover, in vivo TNF alpha administration supported C4HD tumor growth. We also demonstrated, for the first time, that injection of a selective inhibitor of NF-kappa B activity, Bay 11-7082, resulted in regression of TNF alpha-promoted tumor. Bay 11-7082 blocked TNF alpha capacity to induce cell proliferation and up-regulation of cyclin D1 and of Bcl-xLin vivo and in vitro. Our results reveal evidence for TNF alpha as a breast tumor promoter, and provide novel data for a future therapeutic approach using TNF alpha antagonists and NF-kappa B pharmacological inhibitors in established breast cancer treatment.
Assuntos
Carcinoma Ductal de Mama/fisiopatologia , Proliferação de Células/efeitos dos fármacos , Neoplasias Mamárias Experimentais/fisiopatologia , Neoplasias Hormônio-Dependentes/fisiopatologia , Receptores Tipo I de Fatores de Necrose Tumoral/efeitos dos fármacos , Transdução de Sinais/efeitos dos fármacos , Fator de Necrose Tumoral alfa/farmacologia , Animais , Proteínas Reguladoras de Apoptose/efeitos dos fármacos , Proteínas Reguladoras de Apoptose/genética , Proteínas Reguladoras de Apoptose/metabolismo , Carcinógenos , Carcinoma Ductal de Mama/induzido quimicamente , Carcinoma Ductal de Mama/tratamento farmacológico , Linhagem Celular Tumoral , Feminino , Humanos , Proteínas Quinases JNK Ativadas por Mitógeno/efeitos dos fármacos , Proteínas Quinases JNK Ativadas por Mitógeno/metabolismo , Neoplasias Mamárias Experimentais/induzido quimicamente , Neoplasias Mamárias Experimentais/tratamento farmacológico , Acetato de Medroxiprogesterona , Camundongos , Camundongos Endogâmicos BALB C , Proteína Quinase 1 Ativada por Mitógeno/efeitos dos fármacos , Proteína Quinase 1 Ativada por Mitógeno/metabolismo , Proteína Quinase 3 Ativada por Mitógeno/efeitos dos fármacos , Proteína Quinase 3 Ativada por Mitógeno/metabolismo , NF-kappa B/antagonistas & inibidores , NF-kappa B/metabolismo , Neoplasias Hormônio-Dependentes/induzido quimicamente , Neoplasias Hormônio-Dependentes/tratamento farmacológico , Nitrilas/farmacologia , Proteínas Proto-Oncogênicas c-akt/efeitos dos fármacos , Proteínas Proto-Oncogênicas c-akt/metabolismo , Receptores Tipo I de Fatores de Necrose Tumoral/imunologia , Transdução de Sinais/imunologia , Sulfonas/farmacologia , Ativação Transcricional/efeitos dos fármacos , Ativação Transcricional/imunologiaRESUMO
The present study employs an in vitro system to analyse the role of steroid hormones in hCG-induced spermiation in two species of anuran amphibian: Rana catesbeiana and Leptodactylus ocellatus. In vitro spermiation was induced with 10 IU hCG and the effect of different steroid-biosynthesis inhibitors was analysed. Cyanoketone (10(-5)M), an inhibitor of 3-oxo-4-ene steroid biosynthesis, did not block hCG-inducing activity even when biosynthesis of androgen was significantly reduced. These results clearly showed that, in both species, spermiation-inducing action of hCG does not depend on the biosynthesis of 3-oxo-4-ene steroids. Moreover, when combined inhibitors, aminoglutethimide (10(-5)M) plus cyanoketone (10(-5)M), were employed, spermiation evoked by hCG was not modified while hCG-induced androgen secretion significantly decreased. Additionally, none of the steroids used, progesterone, 17, 20 alpha-dihydroxy-4-pregnen-3-one, testosterone and 5 alpha-dihydrotestosterone, were able to induce spermiation in the absence of hCG, confirming that steroids are not involved in that process. In conclusion, as previously described in Bufo arenarum, in L. ocellatus and R. catesbeiana hCG-induced spermiation does not depend on steroid biosynthesis.
Assuntos
Anuros/fisiologia , Rana catesbeiana/fisiologia , Espermatogênese , Esteroides/biossíntese , Androgênios/metabolismo , Animais , Gonadotropina Coriônica/farmacologia , Di-Hidrotestosterona/farmacologia , Humanos , Hidroxiprogesteronas/farmacologia , Masculino , Progesterona/farmacologia , Testosterona/farmacologiaRESUMO
This paper analyzes, in the toad Bufo arenarum, the effect on spermiation and androgen secretion of two human recombinant gonadotropins, human recombinant LH (hrLH) and human recombinant FSH (hrFSH) as well as the well-known spermiation-inducing hormone, human chorionic gonadotropin (hCG). For this purpose, testes were incubated with different concentrations of hrLH (0.01-2.5 microg/ml) and hrFSH (0.05-5 microg/ml), and results were compared with those obtained with 2.5 microg/ml hCG. Spermiation was most efficiently stimulated by hrFSH, which elicited a higher response than either hrLH or hCG. Both hrFSH and hrLH produced a bell-shaped dose-response curve, with a 50% inhibition on spermiation at a concentration twice higher than that necessary to get the highest response. However, none of the gonadotropins yielded a biphasic response on androgen secretion, hrLH producing the highest response at a concentration that evoked a 70% inhibition in the spermiation test. Regarding steroidogenesis, hrLH and hrFSH were more active than hCG. Taken together, the results described in this paper suggest that, in B. arenarum, spermiation and androgen secretion are mediated by different receptors. After comparing the effects of recombinant hormones, we conclude that hrFSH has a greater effect on spermiation than hCG or hrLH.
Assuntos
Bufo arenarum/fisiologia , Hormônio Foliculoestimulante/fisiologia , Hormônio Luteinizante/fisiologia , Espermatogênese/fisiologia , Testículo/fisiologia , Animais , Gonadotropina Coriônica/fisiologia , Relação Dose-Resposta a Droga , Hormônio Foliculoestimulante/administração & dosagem , Humanos , Hormônio Luteinizante/administração & dosagem , Masculino , Espermatogênese/efeitos dos fármacos , Espermatozoides/efeitos dos fármacos , Espermatozoides/fisiologia , Testículo/efeitos dos fármacos , Testículo/metabolismo , Testosterona/biossíntese , Testosterona/metabolismoRESUMO
Interactions between steroid hormone receptors and signal transducer and activator of transcription (Stat)-mediated signaling pathways have already been described. In the present study, we explored the capacity of progestins to modulate Stat3 transcriptional activation in an experimental model of hormonal carcinogenesis in which the synthetic progestin medroxyprogesterone acetate (MPA) induced mammary adenocarcinomas in BALB/c mice and in the human breast cancer cell line T47D. We found that C4HD epithelial cells, from the MPA-induced mammary tumor model, expressed Stat3 and that MPA treatment of C4HD cells up-regulated Stat3 protein expression. In addition, MPA induced rapid, nongenomic Stat3, Jak1, and Jak2 tyrosine phosphorylation in C4HD and T47D cells. MPA treatment of C4HD cells also resulted in rapid c-Src tyrosine phosphorylation. These effects were completely abolished by the progestin antagonist RU486. Abrogation of Jak1 and Jak2 activity by transient transfection of C4HD cells with dominant negative (DN) Jak1 or DN Jak2 vectors, or inhibition of Src activity by preincubation of cells with the Src family kinase inhibitor PP2, blocked the capacity of MPA to induce Stat3 phosphorylation. Treatment of C4HD cells with MPA induced Stat3 binding to DNA. In addition, MPA promoted strong Stat3 transcriptional activation in C4HD and T47D cells that was inhibited by RU486 and by blockage of Jak1, Jak2, and Src activities. To investigate the correlation between MPA-induced Stat3 activation and cell growth, C4HD cells were transiently transfected with a DN Stat3 expression vector, Stat3Y705-F, or with a constitutively activated Stat3 mutant, Stat3-C. While expression of Stat3Y705-F mutant had an inhibitory effect on MPA-induced growth of C4HD cells, transfection with the constitutively activated Stat3-C vector resulted in MPA-independent proliferation. Finally, we addressed the effect of targeting Stat3 in in vivo growth of C4HD breast tumors. Blockage of Stat3 activation by transfection of C4HD cells with the DN Stat3Y705-F expression vector significantly inhibited these cells' ability to form tumors in syngeneic mice. Our results have for the first time demonstrated that progestins are able to induce Stat3 transcriptional activation, which is in turn an obligatory requirement for progestin stimulation of both in vitro and in vivo breast cancer growth.
Assuntos
Proteínas de Ligação a DNA/metabolismo , Progestinas/metabolismo , Proteínas Tirosina Quinases/metabolismo , Proteínas Proto-Oncogênicas/metabolismo , Transativadores/metabolismo , Ativação Transcricional , Quinases da Família src/metabolismo , Transporte Ativo do Núcleo Celular , Animais , Antineoplásicos Hormonais/metabolismo , Neoplasias da Mama , Linhagem Celular Tumoral , DNA/metabolismo , Proteínas de Ligação a DNA/genética , Células Epiteliais/citologia , Células Epiteliais/metabolismo , Feminino , Humanos , Janus Quinase 1 , Janus Quinase 2 , Acetato de Medroxiprogesterona/metabolismo , Camundongos , Camundongos Endogâmicos BALB C , Proteínas Tirosina Quinases/genética , Proteínas Proto-Oncogênicas/genética , Receptores de Progesterona/metabolismo , Fator de Transcrição STAT3 , Transativadores/genética , Quinases da Família src/genéticaRESUMO
In Bufo arenarum, androgen biosynthesis occurs through a complete 5-ene pathway, including 5-androstane-3beta,17beta-diol as the immediate precursor of testosterone. Besides, steroidogenesis changes during the breeding period, turning from androgens to C(21)-steroids such as 5alpha-pregnan-3alpha,20alpha-diol, 3alpha-hydroxy-5alpha-pregnan-20-one and 5alpha-pregnan-3,20-dione. In B. arenarum, steroid hormones are not involved in hCG-induced spermiation, suggesting that the steroidogenic shift to C(21)-steroids during the breeding be not related to spermiation. The activity of 17-hydroxylase-C(17-20) lyase (CypP450(c17)) decreases during the reproductive season, suggesting that this enzyme would represent a key enzyme in the regulation of seasonal changes. However, the increase in the affinity for pregnenolone of 3beta-hydroxysteroid dehydrogenase (3alphaHSD)/isomerase could also be involved. Moreover, the reduction in CypP450(c17) leading to a reduction in C(19)-steroids, among them dehydroepiandrosterone (DHE), would contribute to the conversion of pregnenolone into progesterone, avoiding the non-competitive inhibition exerted by DHE on this transformation. Additionally, CypP450(c17) possesses a higher affinity for pregnenolone than for progesterone, explaining the predominance of the 5-ene pathway for testosterone biosynthesis. Animals in reproductive condition showed a significant reduction in circulating androgens, enhancing the physiological relevance of all the in vitro results. The in vitro effects of mGnRH and hrFSH on testicular steroidogenesis revealed that both hormones inhibited CypP450(c17) activity. In summary, these results demonstrate that, in B. arenarum, the change in testicular steroidogenesis during the reproductive period could be partially due to an FSH and GnRH-induced decrease in CypP450(c17) activity.