RESUMO
Introduction: Intracellular communication is essential for the maintenance of the anterior pituitary gland plasticity. The aim of this study was to evaluate whether GPCR-Gαi modulates basic fibroblast growth factor (FGF2)-induced proliferative activity in normal pituitary cell populations. Methods: Anterior pituitary primary cell cultures from Wistar female rats were treated with FGF2 (10ng/mL) or somatostatin analog (SSTa, 100nM) alone or co-incubated with or without the inhibitors of GPCR-Gαi, pertussis toxin (PTX, 500nM), MEK inhibitor (U0126, 100µM) or PI3K inhibitor (LY 294002, 10 µM). Results: FGF2 increased and SSTa decreased the lactotroph and somatotroph BrdU uptak2e (p<0.05) whereas the FGF2-induced S-phase entry was prevented by SSTa co-incubation in both cell types, with these effects being reverted by PTX, U0126 or LY294002 pre-incubation. The inhibition of lactotroph and somatotroph mitosis was associated with a downregulation of c-Jun expression, a decrease of phosphorylated (p) ERK and pAKT. Furthermore, SSTa was observed to inhibit the S-phase entry induced by FGF2, resulting in a further increase in the number of cells in the G1 phase and a concomitant reduction in the number of cells in the S phases (p< 0.05), effects related to a decrease of cyclin D1 expression and an increase in the expression of the cell cycle inhibitors p27 and p21. Discussion: In summary, the GPCR-Gαi activated by SSTa blocked the pro-proliferative effect of FGF2 in normal pituitary cells via a MEK-dependent mechanism, which acts as a mediator of both anti and pro-mitogenic signals, that may regulate the principal effectors of the G1 to S-phase transition.
Assuntos
Fator 2 de Crescimento de Fibroblastos , Hipófise , Animais , Feminino , Ratos , Proliferação de Células , Fator 2 de Crescimento de Fibroblastos/farmacologia , Quinases de Proteína Quinase Ativadas por Mitógeno , Fosfatidilinositol 3-Quinases/metabolismo , Ratos Wistar , Hipófise/citologia , Hipófise/efeitos dos fármacosRESUMO
This paper describes the development of a coating for cotton and polypropylene (PP) fabrics based on a polymeric matrix embedded with cuprous oxide nanoparticles (Cu2O@SDS NPs) in order to inactivate SARS-CoV-2 and manufactured by a simple process using a dip-assisted layer-by-layer technology, at low curing temperature and without the need for expensive equipment, capable of achieving disinfection rates of up to 99%. The polymeric bilayer coating makes the surface of the fabrics hydrophilic, enabling the transportation of the virus-infected droplets to achieve the rapid inactivation of SARS-CoV-2 by contact with the Cu2O@SDS NPs incorporated in the coated fabrics.
Assuntos
COVID-19 , Nanopartículas , Humanos , SARS-CoV-2 , COVID-19/prevenção & controle , Têxteis , PolímerosRESUMO
INTRODUCTION: Macroautophagy is a lysosome-mediated degradation process that controls the quality of cytoplasmic components and organelles, with its regulation depending on autophagy-related proteins (Atg) and with Beclin1/Atg6 and microtubule-associated protein light chain 3 (LC3/Atg8) being key players in the mammalian autophagy. As reports on this mechanism in the field of pituitary neuropathology and neuroendocrinology are scarce, our study analyzed the ultrastructural signs of macroautophagy and the expression of Beclin1 and LC3 proteins in human functioning PitNETs and in experimental pituitary tumors. METHODS: A group of humans functioning PitNETs and an experimental lactotroph model in rats of the F344 strain stimulated with estradiol benzoate (BE) were used. Ultrastructural and molecular evidence of the macroautophagic process was evaluated using different techniques. RESULTS: In functioning PitNETs cohort, 60% exhibited evidence of macroautophagy, with a significant difference found for Beclin1 and LC3 between macro- and micro-PitNETs (p < 0.05). In the experimental model, the expression of both Beclin1 and LC3 proteins was immunopositive in normal and tumoral glands when analyzed by immunofluorescence, Western blot, and immunohistochemistry. In the experimental model, protein expression was associated with increased glandular size and weight. CONCLUSIONS: Our study revealed evidence of macroautophagy at the pituitary level and the important role of Beclin1 and LC3 in the progression of functioning PitNETs, implying that this mechanism participate in regulating pituitary cell growth.
Assuntos
Macroautofagia , Neoplasias Hipofisárias , Humanos , Ratos , Animais , Proteína Beclina-1 , Ratos Endogâmicos F344 , Autofagia , Proteínas Associadas aos Microtúbulos/metabolismo , Mamíferos/metabolismoRESUMO
To investigate the putative stem cell/tumor stem cell (SC/TSC) niche contribution to hyperplasic/adenomatous pituitary lesions, we analyzed variation in the pituitary stem cell population during the development of experimental pituitary tumors. Pituitary tumors were induced in female F344 rats with estradiol benzoate for 5, 10, 20 and 30 days. Cells positive for GFRa2, Sox2, Sox9, Nestin, CD133 and CD44 were identified in the marginal zone and in the adenoparenchyma in both control and 30D groups, with predominant adenoparenchyma localization of GRFa2 and SOX9 found in tumoral pituitaries. GFRa2, Nestin, CD133 and CD44 were upregulated at the initial stages of tumor growth, whereas Sox9 significantly decreased at 5D, with Sox2 remaining invariable during the hyperplasic/adenomatous development. In addition, isolated pituispheres from normal and tumoral pituitary glands enriched in SC/TSC were characterized. Pituispheres from the 30D glands were positive for the above-mentioned markers and showed a significant increase in the proliferation. In conclusion, our data revealed pituitary SC pool fluctuations during hyperplastic/adenomatous development, with differential localization of the SC/TSC niche in this process. These findings may help to provide a better understanding of these cell populations, which is crucial for achieving advancements in the field of pituitary tumor biology.
Assuntos
Adenoma/patologia , Neoplasias Hipofisárias/patologia , Nicho de Células-Tronco/fisiologia , Animais , Diferenciação Celular , Proliferação de Células , Células Cultivadas , Feminino , Células-Tronco Neoplásicas/patologia , Células-Tronco Neoplásicas/fisiologia , Hipófise/patologia , Hipófise/fisiologia , Ratos , Ratos Endogâmicos F344 , Microambiente Tumoral/fisiologiaRESUMO
BACKGROUND: PTP4A3 is a subclass of a protein tyrosine phosphatase super family and is expressed in a range of epithelial neoplasms. We evaluated PTP4A3 expression and its association with clinicopathological parameters in different types of functioning pituitary adenomas. METHODS: A total of 34 functioning pituitary adenomas samples were evaluated in this observational study. PTP4A3 expression was examined by immunohistochemical staining, and, possible correlations between PTP4A3 and some clinicopathological variables were investigated. RESULTS: PTP4A3 was expressed in 19 out of 34 tumours (55%), at the cytoplasmic level of tumorous cells. Moreover, there was significant association (p=0.042) between PTP4A3 expression and tumorous size. CONCLUSIONS: PTP4A3 was expressed in more than half of the tumours analysed, with there being a significant association with the tumorous size of functioning adenomas. This allows to speculate that PTP4A3 may regulate tumour growth, although further investigations are necessary to determine if this phosphatase can serve as a biomarker or used as a therapeutic target in pituitary macroadenomas.
Assuntos
Adenoma/diagnóstico , Regulação Neoplásica da Expressão Gênica , Proteínas de Neoplasias/metabolismo , Neoplasias Hipofisárias/diagnóstico por imagem , Proteínas Tirosina Fosfatases/metabolismo , Adenoma/metabolismo , Adenoma/patologia , Adulto , Citoplasma/metabolismo , Feminino , Humanos , Imuno-Histoquímica , Masculino , Pessoa de Meia-Idade , Proteínas de Neoplasias/genética , Hipófise/metabolismo , Neoplasias Hipofisárias/metabolismo , Neoplasias Hipofisárias/patologia , Proteínas Tirosina Fosfatases/genética , Estudos Retrospectivos , Adulto JovemRESUMO
Serum prolactin levels gradually increase from birth to puberty in both male and female rats, with higher levels observed in female since the first days of life. The increase in lactotroph secretion was attributed to the maturation of prolactin-inhibiting and prolactin-releasing factors; however, those mechanisms could not fully explain the gender differences observed. Prolactin secretion from isolated lactotrophs, in the absence of hypothalamic control, also increases during the first weeks of life, suggesting the involvement of intra-pituitary factors. We postulate that pituitary transforming growth factor beta 1 (TGFß1) is involved in the regulation of prolactin secretion as well as in the gender differences observed at early postnatal age. Several components of the local TGFß1 system were evaluated during postnatal development (11, 23, and 45 days) in female and male Sprague-Dawley rats. In vivo assays were performed to study local TGFß1 activation and its impact on prolactin secretion. At day 11, female pituitaries present high levels of active TGFß1, concomitant with the highest expression of TGFß1 target genes and the phospho-Smad3 immunostaining in lactotrophs. The steady increase in prolactin secretion inversely correlates with active TGFß1 levels only in females. Dopamine and estradiol induce TGFß1 activation at day 11, in both genders, but its activation induces the inhibition of prolactin secretion only in females. Our findings demonstrate that: (1) TGFß1 activation is regulated by dopamine and estradiol; (2) the inhibitory regulation of local TGFß1 on prolactin secretion is gender specific; and (3) this mechanism is responsible, at least partially, for the gender differences observed being relevant during postnatal development.
Assuntos
Fator de Crescimento Transformador beta1/metabolismo , Animais , Dopamina/farmacologia , Estradiol/farmacologia , Feminino , Lactotrofos/efeitos dos fármacos , Lactotrofos/metabolismo , Masculino , Prolactina/metabolismo , Ratos , Ratos Sprague-Dawley , Caracteres Sexuais , Proteína Smad3/metabolismoRESUMO
In pituitary adenomas, early recurrences and resistance to conventional pharmacotherapies are common, but the mechanisms involved are still not understood. The high expression of epidermal growth factor receptor 2 (HER2)/extracellular signal-regulated kinase (ERK1/2) signal observed in human pituitary adenomas, together with the low levels of the antimitogenic transforming growth factor beta receptor 2 (TBR2), encouraged us to evaluate the effect of the specific HER2 inhibition with trastuzumab on experimental pituitary tumor cell growth and its effect on the antiproliferative response to TGFB1. Trastuzumab decreased the pituitary tumor growth as well as the expression of ERK1/2 and the cell cycle regulators CCND1 and CDK4. The HER2/ERK1/2 pathway is an attractive therapeutic target, but its intricate relations with other signaling modulators still need to be unraveled. Thus, we investigated possible cross-talk with TGFB signaling, which has not yet been studied in pituitary tumors. In tumoral GH3 cells, co-incubation with trastuzumab and TGFB1 significantly decreased cell proliferation, an effect accompanied by a reduction in ERK1/2 phosphorylation, an increase of SMAD2/3 activation. In addition, through immunoprecipitation assays, a diminution of SMAD2/3-ERK1/2 and an increase SMAD2/3-TGFBR1 interactions were observed when cells were co-incubated with trastuzumab and TGFB1. These findings indicate that blocking HER2 by trastuzumab inhibited pituitary tumor growth and modulated HER2/ERK1/2 signaling and consequently the anti-mitogenic TGFB1/TBRs/SMADs cascade. The imbalance between HER2 and TGFBRs expression observed in human adenomas and the response to trastuzumab on experimental tumor growth may make the HER2/ERK1/2 pathway an attractive target for future pituitary adenoma therapy.
Assuntos
Adenoma/metabolismo , Proliferação de Células/efeitos dos fármacos , Neoplasias Hipofisárias/metabolismo , Transdução de Sinais/efeitos dos fármacos , Proteínas Smad/metabolismo , Fator de Crescimento Transformador beta/metabolismo , Trastuzumab/farmacologia , Adenoma/patologia , Adulto , Ciclo Celular/efeitos dos fármacos , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Fosforilação , Neoplasias Hipofisárias/patologia , Adulto JovemRESUMO
The cellular transformation of normal functional cells to neoplastic ones implies alterations in the cellular metabolism and mitochondrial function in order to provide the bioenergetics and growth requirements for tumour growth progression. Currently, the mitochondrial physiology and dynamic shift during pituitary tumour development are not well understood. Pituitary tumours present endocrine neoplastic benign growth which, in previous reports, we had shown that in addition to increased proliferation, these tumours were also characterized by cellular senescence signs with no indication of apoptosis. Here, we show clear evidence of oxidative stress in pituitary cells, accompanied by bigger and round mitochondria during tumour development, associated with augmented biogenesis and an increased fusion process. An activation of the Nrf2 stress response pathway together with the attenuation of the oxidative damage signs occurring during tumour development were also observed which will probably provide survival advantages to the pituitary cells. These neoplasms also presented a progressive increase in lactate production, suggesting a metabolic shift towards glycolysis metabolism. These findings might imply an oxidative stress state that could impact on the pathogenesis of pituitary tumours. These data may also reflect that pituitary cells can modulate their metabolism to adapt to different energy requirements and signalling events in a pathophysiological situation to obtain protection from damage and enhance their survival chances. Thus, we suggest that mitochondria function, oxidative stress or damage might play a critical role in pituitary tumour progression.
Assuntos
Transformação Celular Neoplásica/metabolismo , Mitocôndrias/metabolismo , Estresse Oxidativo/fisiologia , Neoplasias Hipofisárias/metabolismo , Adaptação Fisiológica/fisiologia , Animais , Antioxidantes/metabolismo , Metabolismo Energético/fisiologia , Ratos , Ratos Wistar , Espécies Reativas de Oxigênio/metabolismoRESUMO
Pituitary tumor cells have a poor response to the growth inhibitory effect of TGFß1, possibly resulting from the cross talk of TGFß/Smads signal with other signaling pathways, an undescribed mechanism in these tumoral cells. To address this hypothesis, we investigated whether the mitogen-activated extracellular signal-regulated kinase (MEK)/ERK1/2 and phosphoinositide-3 kinase/protein kinase B (PI3K/Akt) pathways were able to regulate the antimitogenic effect of TGFß1 on GH3B6 cells. TGFß1 treatment decreased the cell proliferation and induced an activation of mothers against decapentaplegic homolog 2/3 (Smad2/3), effects that were potentiated by MEK and PI3K inhibitors, thus indicating the existence of a cross talk between TGFß1/Smad with the MEK/ERK1/2 or PI3K/Akt pathways. In addition, through immunoprecipitation assays, a direct interaction was observed between Smad2/3-ERK1/2 and Smad2/3-Akt, which decreased when the GH3B6 cells were incubated with TGFß1 in the presence of MEK or PI3K inhibitors, thereby suggesting that the ERK1/2- and Akt-activated states were involved. These Smad2/3-ERK1/2 and Smad2/3-Akt associations were also confirmed by confocal and transmission electron microscopy. These findings indicate that the TGFß1-antimitogenic effect in GH3B6 cells was attenuated by the MEK/ERK1/2 and PI3K/Akt pathways via modulating Smad2/3 phosphorylation. This molecular mechanism could explain in part the refractory behavior of pituitary tumor cells to the inhibitory effect of TGFß1.
Assuntos
Adenoma/metabolismo , Sistema de Sinalização das MAP Quinases , Fosfatidilinositol 3-Quinases/metabolismo , Neoplasias Hipofisárias/metabolismo , Proteínas Proto-Oncogênicas c-akt/metabolismo , Fator de Crescimento Transformador beta1/metabolismo , Animais , Carcinogênese , Linhagem Celular Tumoral , Prolactina/metabolismo , Ratos , Proteínas Smad/metabolismoRESUMO
Toll like receptor 4 (TLR4) has been characterized for its ability to recognize bacterial endotoxin lipopolysaccharide (LPS). Considering that infections or inflammatory processes might contribute to the progression of pituitary tumors, we analyzed the TLR4 functional role by evaluating the LPS effect on lactotroph proliferation in primary cultures from experimental pituitary tumors, and examined the involvement of PI3K-Akt and NF-κB activation in this effect. In addition, the role of 17ß-estradiol as a possible modulator of LPS-induced PRL cell proliferation was further investigated. In estrogen-induced hyperplasic pituitaries, LPS triggered lactotroph cell proliferation. However, endotoxin failed to increase the number of lactotrophs taking up BrdU in normal pituitaries. Moreover, incubation with anti-TLR4 antibody significantly reduced LPS-induced lactotroph proliferation, suggesting a functional role of this receptor. As a sign of TLR4 activation, an LPS challenge increased IL-6 release in normal and tumoral cells. By flow cytometry, TLR4 baseline expression was revealed at the plasma membrane of tumoral lactotrophs, without changes noted in the percentage of double PRL/TLR4 positive cells after LPS stimulus. Increases in TLR4 intracellular expression were detected as well as rises in CD14, p-Akt and NF-κB after an LPS challenge, as assessed by western blotting. The TLR4/PRL and PRL/NF-κB co-localization was also corroborated by immunofluorescence and the involvement of PI3K/Akt signaling in lactotroph proliferation and IL-6 release was revealed through the PI3K inhibitor Ly-294002. In addition, 17ß-estradiol attenuated the LPS-evoked increase in tumoral lactotroph proliferation and IL-6 release. Collectively these results demonstrate the presence of functional TLR4 in lactotrophs from estrogen-induced hyperplasic pituitaries, which responded to the proliferative stimulation and IL-6 release induced by LPS through TLR4/CD14, with a contribution of the PI3K-Akt and NF-κB signaling pathways.
Assuntos
Proliferação de Células/efeitos dos fármacos , Lipopolissacarídeos/farmacologia , Hipófise/metabolismo , Neoplasias Hipofisárias/metabolismo , Receptor 4 Toll-Like/metabolismo , Animais , Células Cultivadas , Hiperplasia/metabolismo , Interleucina-6/metabolismo , Masculino , NF-kappa B/metabolismo , Fosfatidilinositol 3-Quinases/metabolismo , Hipófise/ultraestrutura , Neoplasias Hipofisárias/imunologia , Neoplasias Hipofisárias/ultraestrutura , Proteínas Proto-Oncogênicas c-akt/metabolismo , Ratos , Ratos Wistar , Transdução de Sinais/fisiologiaRESUMO
Prostate smooth muscle cells (pSMCs) are capable of responding to inflammatory stimuli by secreting proinflammatory products, which causes pSMCs to undergo dedifferentiation. Although it has been proposed that androgens decrease proinflammatory molecules in many cells and under various conditions, the role of testosterone in the prostate inflammatory microenvironment is still unclear. Therefore, our aim was to evaluate if testosterone was able to modulate the pSMCs response to bacterial LPS by stimulating primary pSMC cultures, containing testosterone or vehicle, with LPS (1 or 10 µg/ml) for 24-48 h. The LPS challenge induced pSMCs dedifferentiation as evidenced by a decrease of calponin and alpha smooth muscle actin along with an increase of vimentin in a dose-dependent manner, whereas testosterone abrogated these alterations. Additionally, an ultrastructural analysis showed that pSMCs acquired a secretory profile after LPS and developed proteinopoietic organelles, while pSMCs preincubated with testosterone maintained a more differentiated phenotype. Testosterone downregulated the expression of surface TLR4 in control cells and inhibited any increase after LPS treatment. Moreover, testosterone prevented IκB-α degradation and the LPS-induced NF-κB nuclear translocation. Testosterone also decreased TNF-α and IL6 production by pSMCs after LPS as quantified by ELISA. Finally, we observed that testosterone inhibited the induction of pSMCs proliferation incited by LPS. Taken together, these results indicate that testosterone reduced the proinflammatory pSMCs response to LPS, with these cells being less reactive in the presence of androgens. In this context, testosterone might have a homeostatic role by contributing to preserve a contractile phenotype on pSMCs under inflammatory conditions.
Assuntos
Miócitos de Músculo Liso/citologia , Miócitos de Músculo Liso/metabolismo , Próstata/citologia , Próstata/metabolismo , Testosterona/metabolismo , Receptor 4 Toll-Like/metabolismo , Animais , Diferenciação Celular/efeitos dos fármacos , Proliferação de Células/efeitos dos fármacos , Citocinas/biossíntese , Mediadores da Inflamação/metabolismo , Lipopolissacarídeos/farmacologia , Masculino , Modelos Biológicos , Miócitos de Músculo Liso/efeitos dos fármacos , NF-kappa B/metabolismo , Fenótipo , Próstata/efeitos dos fármacos , Ratos , Ratos Wistar , Testosterona/farmacologiaRESUMO
BACKGROUND: In this report, we explored the role of PKCalpha and PKCe as mediators of phorbol 12-myristate13-acetate (PMA)-induced proliferation in pituitary tumor GH3B6 cells, and determined if the ERK1/2 and Akt pathways were activated. METHODS: The GH3B6 cell proliferation was estimated by BrdU incorporation and the cell cycle progression by flow cytometric cell cycle analysis. We determined the expression of PKCalpha and PKCe in membrane and cytosolic fractions by western blotting. The subcellular redistribution of both PKC isozymes was analyzed by confocal microscopy. RESULTS: Incubation with PMA for 15 min stimulated PKCalpha and PKCe activation, which was correlated with the phosphorylation of ERK1/2 but not Akt. The activation of both these PKC isozymes was closely associated with the stimulation of proliferation and the cell cycle progression induced by PMA in GH3B6 cells, an effect that was blocked by the inhibitors of PKCalpha (Gö6976) and PKCe (eV1-2). In addition, the pretreatment with the inhibitor of ERK1/2 (PD98059) prevented the mitogenic activity induced by treatment with PMA for 15 min. CONCLUSION: We demonstrated that the activation of PKCalpha and PKCe by phorbol ester in tumor pituitary GH3B6 cells led to cell proliferation and cell cycle progression, effects that involved ERK1/2 activation.
Assuntos
Proteína Quinase 1 Ativada por Mitógeno/metabolismo , Proteína Quinase 3 Ativada por Mitógeno/metabolismo , Neoplasias Hipofisárias/enzimologia , Proteína Quinase C-alfa/metabolismo , Proteína Quinase C-épsilon/metabolismo , Animais , Bromodesoxiuridina/farmacologia , Proliferação de Células , Flavonoides/farmacologia , Citometria de Fluxo , Proteína Quinase 1 Ativada por Mitógeno/antagonistas & inibidores , Proteína Quinase 3 Ativada por Mitógeno/antagonistas & inibidores , Fosforilação , Proteína Quinase C-alfa/antagonistas & inibidores , Proteína Quinase C-épsilon/antagonistas & inibidores , Ratos , Transdução de Sinais , Acetato de Tetradecanoilforbol/análogos & derivados , Acetato de Tetradecanoilforbol/farmacologia , Células Tumorais CultivadasRESUMO
Bromocriptine (Bc) produces pituitary tumoral mass regression which induces the cellular death that was classically described as apoptosis. However, recent works have related that other mechanisms of cell death could also be involved in the maintenance of physiological and pathological pituitary homeostasis. The aim of this study was to evaluate and characterize the different types of cell death in the involution induced by Bc in experimental rat pituitary tumors. The current study demonstrated that Bc induced an effective regression of estrogen induced pituitary tumors by a mechanism identified as parapoptosis. This alternative cell death was ultrastructurally recognized by extensive cytoplasmic vacuolization and an increased cell electron density, represented around 25% of the total pituitary cells counted. Furthermore, the results obtained from biochemical assays did not correspond to the criteria of apoptosis or necrosis. We also investigated the participation of p38, ERK1/2 and PKC delta in the parapoptotic pathway. An important observation was the significant increase in phosphorylated forms of these MAPKs, the holoenzyme and catalytic fragments of PKC delta in nuclear fractions after Bc administration compared to control and estrogen treated rats. Furthermore, the immunolocalization at ultrastructural level of these kinases showed a similar distribution pattern, with a prevalent localization at nuclear level in lactotrophs from Bc treated rats. In summary, we determined that parapoptosis is the predominant cell death type involved in the regression of pituitary tumors in response to Bc treatment, and may cause the activation of PKC delta, ERK1/2 and p38.
Assuntos
Apoptose/efeitos dos fármacos , Bromocriptina/uso terapêutico , Neoplasias Hipofisárias/tratamento farmacológico , Neoplasias Hipofisárias/patologia , Prolactinoma/tratamento farmacológico , Prolactinoma/patologia , Animais , Apoptose/fisiologia , Morte Celular/efeitos dos fármacos , Morte Celular/fisiologia , MAP Quinase Quinase 2/fisiologia , Masculino , Proteína Quinase 3 Ativada por Mitógeno/fisiologia , Neoplasias Hipofisárias/enzimologia , Prolactinoma/enzimologia , Proteína Quinase C-delta/fisiologia , Ratos , Ratos Wistar , Proteínas Quinases p38 Ativadas por Mitógeno/fisiologiaRESUMO
The variations of the intracellular localization of the individual protein kinase C (PKC) isoforms are related with their different biological functions. In this study, we have investigated the precise intracellular translocation of endogenous PKCalpha and PKCepsilon in PMA-stimulated normal and tumoral lactotroph cells by using confocal and immunogold electron microscopy, which was correlated with the rate of cell proliferation of both pituitary cell phenotypes. The present results showed that the short phorbol ester incubation stimulated the proliferation of normal and tumoral lactotroph cells, as determined by the measurement of the BrdU-labelling index. The translocation of PKCalpha to plasma and nuclear membranes induced by PMA was more marked than that observed for PKCepsilon in normal and tumoral lactotroph cells. Our results showed that PKCs translocation to the plasma and nuclear membranes varied from isozyme to isozyme emphasizing that PKCalpha could be related with the mitogenic stimulus exerted by phorbol ester. These data support the notion that specific PKC isozymes may exert spatially defined effects by virtue of their directed translocation to distinct intracellular sites.
Assuntos
Lactotrofos/enzimologia , Lactotrofos/patologia , Proteína Quinase C-alfa/metabolismo , Proteína Quinase C-épsilon/metabolismo , Acetato de Tetradecanoilforbol/farmacologia , Animais , Linhagem Celular Tumoral , Proliferação de Células/efeitos dos fármacos , Feminino , Imunofluorescência , Lactotrofos/efeitos dos fármacos , Lactotrofos/ultraestrutura , Mitógenos/farmacologia , Membrana Nuclear/efeitos dos fármacos , Membrana Nuclear/enzimologia , Membrana Nuclear/ultraestrutura , Neoplasias Hipofisárias/enzimologia , Neoplasias Hipofisárias/patologia , Neoplasias Hipofisárias/ultraestrutura , Proteína Quinase C-alfa/ultraestrutura , Proteína Quinase C-épsilon/ultraestrutura , Transporte Proteico/efeitos dos fármacos , Ratos , Frações Subcelulares/efeitos dos fármacos , Frações Subcelulares/enzimologiaRESUMO
The aim of this investigation was to contribute to current knowledge about intracellular mechanisms that are involved in lactotroph cell proliferation, by evaluating the role of PKCalpha, PKCepsilon and extracellular-signal regulated kinase (ERK) 1/2 in response to phorbol 12-myristate13-acetate (PMA). In primary pituitary cultures, the activation of protein kinase C (PKC) by PMA for 15 min stimulated lactotroph proliferation; whereas a prolonged activation for 3-8h diminished this proliferative effect. The use of PMA for 15 min-activated PKCepsilon and ERK1/2, whereas incubation with PMA for 3 h induced PKCalpha activation and attenuated the PMA-triggered phosphorylation of ERK1/2. The following inhibitors: PKCs (bisindolylmaleimide I), PKCepsilon (epsilonV1 peptide) and ERK1/2 (PD98059) prevented the mitogenic activity induced by PMA for 15 min. Lactotroph cells stimulated with PMA for 15 min showed a translocation of PKCepsilon to membrane compartment and nucleus. These results thus establish that PKCepsilon plays an essential role in the lactotroph proliferation induced by PMA by triggering signals that involve ERK1/2 activation.
Assuntos
Proliferação de Células/efeitos dos fármacos , Lactotrofos/citologia , Lactotrofos/fisiologia , Proteína Quinase C-épsilon/metabolismo , Acetato de Tetradecanoilforbol/farmacologia , Animais , Células Cultivadas , Ativação Enzimática/efeitos dos fármacos , Feminino , Sistema de Sinalização das MAP Quinases/efeitos dos fármacos , Proteína Quinase 3 Ativada por Mitógeno/metabolismo , Transporte Proteico/efeitos dos fármacos , Ratos , Ratos WistarRESUMO
The effects of IGF-1, 17 beta oestradiol and its functional interaction on lactotrophs cell proliferation were evaluated. In addition we investigated the involvement of PKC alpha, epsilon and phosphorilated ERK, in the mitogenic process. Primary cell cultures of adenohypophysis from female Wistar rats were studied in serum free conditions. The proliferation of lactotrophs was determined by double immunostaining for BrdU and PRL. The incubation with IGF-1 5, 30 or 100 ng/ml during 48 or 72 h increased lactotrophs proliferation two-threefold depending on IGF-1 concentration. Co-incubation of IGF-1 (30 ng/ml) with genistein (25 microM) or BIM (0.5 or 2 microM), lowered of tyrosine kinase receptor or of PKC respectively, inhibited the induced IGF-1 lactotrophs proliferation. 17 beta oestradiol (1, 10 or 100 nM) had not mitogenic effect, whereas in the presence of serum PRL cells proliferation was stimulated. Co-incubation with 1 nM oestradiol and IGF-1 significantly decreased the lactotroph BrdU-labelling achieved with IGF-1. PKC alpha, epsilon and ERK1/2 levels measured by western blot augmented in the presence of IGF-1 and were inhibited with the addition of genistein, supporting a participation of these enzymes in the proliferate process. Co-incubation of IGF-1 with 1 nM oestradiol decreased both PKC isoforms and activated ERK1/2 levels, suggesting that oestradiol would exert its antiproliferative effect by acting on the signalling pathway of IGF-1. The results revealed antagonic effects of oestradiol on lactotroph proliferation depending on its concentration and the presence of IGF-1.