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Recurrent gene fusions (GFs) in translocated sarcomas are recognized as major oncogenic drivers of the disease, as well as diagnostic markers whose identification is necessary for differential diagnosis. EWSR1 is a 'promiscuous' gene that can fuse with many different partner genes, defining different entities among a broad range of mesenchymal neoplasms. Molecular testing of EWSR1 translocation traditionally relies on FISH assays with break-apart probes, which are unable to identify the fusion partner. Therefore, other ancillary molecular diagnostic modalities are being increasingly adopted for accurate classification of these neoplasms. Herein, we report three cases with rare GFs involving EWSR1 in undifferentiated mesenchymal neoplasms with uncertain differential diagnoses, using targeted RNA-seq and confirming with RT-PCR and Sanger sequencing. Two GFs involved hormone nuclear receptors as 3' partners, NR4A2 and RORB, which have not been previously reported. NR4A2 may functionally replace NR4A3, the usual 3' partner in extraskeletal myxoid chondrosarcoma. The third GF, EWSR1::BEND2, has previously been reported in a subtype of astroblastoma and other rare entities, including a single case of a soft-tissue tumor that we discuss in this work. In conclusion, our findings indicate that the catalogue of mesenchymal neoplasm-bearing EWSR1 fusions continues to grow, underscoring the value of using molecular ancillary techniques with higher diagnostic abilities in the routine clinical setting.
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Neoplasias de Tecido Conjuntivo e de Tecidos Moles , Proteínas de Fusão Oncogênica , Proteína EWS de Ligação a RNA , Neoplasias de Tecidos Moles , Humanos , Proteínas de Ligação a Calmodulina/genética , Condrossarcoma/genética , Proteínas de Fusão Oncogênica/genética , Proteína EWS de Ligação a RNA/genética , Proteínas de Ligação a RNA/genética , Sarcoma/patologia , Neoplasias de Tecidos Moles/genéticaRESUMO
The transcription factor, early growth response-1 (EGR-1), is involved in the regulation of cell differentiation, proliferation, and apoptosis in response to different stimuli. EGR-1 is described to be involved in pancreatic endoderm differentiation, but the regulatory mechanisms controlling its action are not fully elucidated. Our previous investigation reported that exposure of mouse embryonic stem cells (mESCs) to the chemical nitric oxide (NO) donor diethylenetriamine nitric oxide adduct (DETA-NO) induces the expression of early differentiation genes such as pancreatic and duodenal homeobox 1 (Pdx1). We have also evidenced that Pdx1 expression is associated with the release of polycomb repressive complex 2 (PRC2) and P300 from the Pdx1 promoter; these events were accompanied by epigenetic changes to histones and site-specific changes in the DNA methylation. Here, we investigate the role of EGR-1 on Pdx1 regulation in mESCs. This study reveals that EGR-1 plays a negative role in Pdx1 expression and shows that the binding capacity of EGR-1 to the Pdx1 promoter depends on the methylation level of its DNA binding site and its acetylation state. These results suggest that targeting EGR-1 at early differentiation stages might be relevant for directing pluripotent cells into Pdx1-dependent cell lineages.
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Endoderma , Células-Tronco Embrionárias Murinas , Animais , Diferenciação Celular/genética , Células-Tronco Embrionárias , Endoderma/metabolismo , Camundongos , Óxido Nítrico/metabolismoRESUMO
Endoglin (ENG) is a mesenchymal stem cell (MSC) marker typically expressed by active endothelium. This transmembrane glycoprotein is shed by matrix metalloproteinase 14 (MMP14). Our previous work demonstrated potent preclinical activity of first-in-class anti-ENG antibody-drug conjugates as a nascent strategy to eradicate Ewing sarcoma (ES), a devastating rare bone/soft tissue cancer with a putative MSC origin. We also defined a correlation between ENG and MMP14 expression in ES. Herein, we show that ENG expression is significantly associated with a dismal prognosis in a large cohort of ES patients. Moreover, both ENG/MMP14 are frequently expressed in primary ES tumors and metastasis. To deepen in their functional relevance in ES, we conducted transcriptomic and proteomic profiling of in vitro ES models that unveiled a key role of ENG and MMP14 in cell mechano-transduction. Migration and adhesion assays confirmed that loss of ENG disrupts actin filament assembly and filopodia formation, with a concomitant effect on cell spreading. Furthermore, we observed that ENG regulates cell-matrix interaction through activation of focal adhesion signaling and protein kinase C expression. In turn, loss of MMP14 contributed to a more adhesive phenotype of ES cells by modulating the transcriptional extracellular matrix dynamics. Overall, these results suggest that ENG and MMP14 exert a significant role in mediating correct spreading machinery of ES cells, impacting the aggressiveness of the disease.
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Neoplasias Ósseas , Endoglina/metabolismo , Sarcoma de Ewing , Neoplasias Ósseas/genética , Endoglina/genética , Humanos , Metaloproteinase 14 da Matriz/genética , Metaloproteinase 14 da Matriz/metabolismo , Proteômica , Receptores de Fatores de Crescimento , Sarcoma de Ewing/patologia , Transdução de SinaisRESUMO
Solitary fibrous tumor is a rare subtype of soft-tissue sarcoma with a wide spectrum of histopathological features and clinical behaviors, ranging from mildly to highly aggressive tumors. The defining genetic driver alteration is the gene fusion NAB2-STAT6, resulting from a paracentric inversion within chromosome 12q, and involving several different exons in each gene. STAT6 (signal transducer and activator of transcription 6) nuclear immunostaining and/or the identification of NAB2-STAT6 gene fusion is required for the diagnostic confirmation of solitary fibrous tumor. In the present study, a new gene fusion consisting of Nuclear Factor I X (NFIX), mapping to 19p13.2 and STAT6, mapping to 12q13.3 was identified by targeted RNA-Seq in a 74-year-old female patient diagnosed with a deep-seated solitary fibrous tumor in the pelvis. Histopathologically, the neoplasm did not display nuclear pleomorphism or tumor necrosis and had a low proliferative index. A total of 378 unique reads spanning the NFIXexon8-STAT6exon2 breakpoint with 55 different start sites were detected in the bioinformatic analysis, which represented 59.5% of the reads intersecting the genomic location on either side of the breakpoint. Targeted RNA-Seq results were validated by RT-PCR/ Sanger sequencing. The identification of a new gene fusion partner for STAT6 in solitary fibrous tumor opens intriguing new hypotheses to refine the role of STAT6 in the sarcomatogenesis of this entity.
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Fusão Gênica , Fatores de Transcrição NFI/genética , Proteínas de Fusão Oncogênica/genética , Fator de Transcrição STAT6/genética , Tumores Fibrosos Solitários/genética , Tumores Fibrosos Solitários/patologia , Idoso , Feminino , Humanos , PrognósticoRESUMO
Nitric oxide (NO) delays mouse embryonic stem cell (mESC) differentiation by regulating genes linked to pluripotency and differentiation. Nevertheless, no profound study has been conducted on cell differentiation regulation by this molecule through signaling on essential biological functions. We sought to demonstrate that NO positively regulates the pluripotency transcriptional core, enforcing changes in the chromatin structure, in addition to regulating cell proliferation, and signaling pathways with key roles in stemness. Culturing mESCs with 2 µM of the NO donor diethylenetriamine/NO (DETA/NO) in the absence of leukemia inhibitory factor (LIF) induced significant changes in the expression of 16 genes of the pluripotency transcriptional core. Furthermore, treatment with DETA/NO resulted in a high occupancy of activating H3K4me3 at the Oct4 and Nanog promoters and repressive H3K9me3 and H3k27me3 at the Brachyury promoter. Additionally, the activation of signaling pathways involved in pluripotency, such as Gsk3-ß/ß-catenin, was observed, in addition to activation of PI3 K/Akt, which is consistent with the protection of mESCs from cell death. Finally, a decrease in cell proliferation coincides with cell cycle arrest in G2/M. Our results provide novel insights into NO-mediated gene regulation and cell proliferation and suggest that NO is necessary but not sufficient for the maintenance of pluripotency and the prevention of cell differentiation. J. Cell. Biochem. 117: 2078-2088, 2016. © 2016 Wiley Periodicals, Inc.
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Diferenciação Celular/fisiologia , Pontos de Checagem da Fase G2 do Ciclo Celular/fisiologia , Expressão Gênica/fisiologia , Pontos de Checagem da Fase M do Ciclo Celular/fisiologia , Células-Tronco Embrionárias Murinas/metabolismo , Óxido Nítrico/metabolismo , Transdução de Sinais/fisiologia , Animais , Diferenciação Celular/efeitos dos fármacos , Linhagem Celular , Pontos de Checagem da Fase G2 do Ciclo Celular/efeitos dos fármacos , Expressão Gênica/efeitos dos fármacos , Pontos de Checagem da Fase M do Ciclo Celular/efeitos dos fármacos , Camundongos , Células-Tronco Embrionárias Murinas/citologia , Fosfatidilinositol 3-Quinases/metabolismo , Proteínas Proto-Oncogênicas c-akt/metabolismo , Transdução de Sinais/efeitos dos fármacos , Triazenos/farmacologiaRESUMO
BACKGROUND: Undifferentiated small round cell sarcomas (URCSs) represent a diagnostic challenge, and their optimal treatment is unknown. We aimed to define the clinical characteristics, treatment, and outcome of URCS patients. METHODS: URCS patients treated from 1983 to 2019 at 21 worldwide sarcoma reference centres were retrospectively identified. Based on molecular assessment, cases were classified as follows: (1) CIC-rearranged round cell sarcomas, (2) BCOR::CCNB3-rearranged round cell sarcomas, (3) unclassified URCSs. Treatment, prognostic factors and outcome were reviewed. RESULTS: In total, 148 patients were identified [88/148 (60%) CIC-rearranged sarcoma (median age 32 years, range 7-78), 33/148 (22%) BCOR::CCNB3-rearranged (median age 17 years, range 5-91), and 27/148 (18%) unclassified URCSs (median age 37 years, range 4-70)]. One hundred-one (68.2%) cases presented with localised disease; 47 (31.8%) had metastases at diagnosis. Male prevalence, younger age, bone primary site, and a low rate of synchronous metastases were observed in BCOR::CCNB3-rearranged cases. Local treatment was surgery in 67/148 (45%) patients, and surgery + radiotherapy in 52/148 (35%). Chemotherapy was given to 122/148 (82%) patients. At a 42.7-month median follow-up, the 3-year overall survival (OS) was 92.2% (95% CI 71.5-98.0) in BCOR::CCNB3 patients, 39.6% (95% CI 27.7-51.3) in CIC-rearranged sarcomas, and 78.7% in unclassified URCSs (95% CI 56.1-90.6; p < 0.0001). CONCLUSIONS: This study is the largest conducted in URCS and confirms major differences in outcomes between URCS subtypes. A full molecular assessment should be undertaken when a diagnosis of URCS is suspected. Prospective studies are needed to better define the optimal treatment strategy in each URCS subtype.
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Sarcoma de Células Pequenas , Sarcoma , Neoplasias de Tecidos Moles , Adolescente , Adulto , Idoso , Idoso de 80 Anos ou mais , Criança , Pré-Escolar , Humanos , Masculino , Pessoa de Meia-Idade , Adulto Jovem , Biomarcadores Tumorais/genética , Ciclina B , Proteínas de Fusão Oncogênica , Proteínas Proto-Oncogênicas/genética , Proteínas Repressoras/genética , Estudos Retrospectivos , Sarcoma/genética , Sarcoma/terapia , Sarcoma/patologia , Sarcoma de Células Pequenas/genética , Sarcoma de Células Pequenas/terapia , Sarcoma de Células Pequenas/diagnóstico , Neoplasias de Tecidos Moles/patologiaRESUMO
The Hippo pathway is an evolutionarily conserved modulator of developmental biology with a key role in tissue and organ size regulation under homeostatic conditions. Like other signaling pathways with a significant role in embryonic development, the deregulation of Hippo signaling contributes to oncogenesis. Central to the Hippo pathway is a conserved cascade of adaptor proteins and inhibitory kinases that converge and regulate the activity of the oncoproteins YAP and TAZ, the final transducers of the pathway. Elevated levels and aberrant activation of YAP and TAZ have been described in many cancers. Though most of the studies describe their pervasive activation in epithelial neoplasms, there is increasing evidence pointing out its relevance in mesenchymal malignancies as well. Interestingly, somatic or germline mutations in genes of the Hippo pathway are scarce compared to other signaling pathways that are frequently disrupted in cancer. However, in the case of sarcomas, several examples of genetic alteration of Hippo members, including gene fusions, have been described during the last few years. Here, we review the current knowledge of Hippo pathway implication in sarcoma, describing mechanistic hints recently reported in specific histological entities and how these alterations represent an opportunity for targeted therapy in this heterogeneous group of neoplasm.
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Nitric oxide (NO) is a gaseous biomolecule endogenously synthesized with an essential role in embryonic development and several physiological functions, such as regulating mitochondrial respiration and modulation of the immune response. The dual role of NO in embryonic stem cells (ESCs) has been previously reported, preserving pluripotency and cell survival or inducing differentiation with a dose-dependent pattern. In this line, high doses of NO have been used in vitro cultures to induce focused differentiation toward different cell lineages being a key molecule in the regenerative medicine field. Moreover, optimal conditions to promote pluripotency in vitro are essential for their use in advanced therapies. In this sense, the molecular mechanisms underlying stemness regulation by NO have been studied intensively over the current years. Recently, we have reported the role of low NO as a hypoxia-like inducer in pluripotent stem cells (PSCs), which supports using this molecule to maintain pluripotency under normoxic conditions. In this review, we stress the role of NO levels on stem cells (SCs) fate as a new approach for potential cell therapy strategies. Furthermore, we highlight the recent uses of NO in regenerative medicine due to their properties regulating SCs biology.
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The incidence of new cancer cases is expected to increase significantly in the future, posing a worldwide problem. In this regard, precision oncology and its diagnostic tools are essential for developing personalized cancer treatments. Digital pathology (DP) is a particularly key strategy to study the interactions of tumor cells and the tumor microenvironment (TME), which play a crucial role in tumor initiation, progression and metastasis. The purpose of this study was to integrate data on the digital patterns of reticulin fiber scaffolding and the immune cell infiltrate, transcriptomic and epigenetic profiles in aggressive uterine adenocarcinoma (uADC), uterine leiomyosarcoma (uLMS) and their respective lung metastases, with the aim of obtaining key TME biomarkers that can help improve metastatic prediction and shed light on potential therapeutic targets. Automatized algorithms were used to analyze reticulin fiber architecture and immune infiltration in colocalized regions of interest (ROIs) of 133 invasive tumor front (ITF), 89 tumor niches and 70 target tissues in a total of six paired samples of uADC and nine of uLMS. Microdissected tissue from the ITF was employed for transcriptomic and epigenetic studies in primary and metastatic tumors. Reticulin fiber scaffolding was characterized by a large and loose reticular fiber network in uADC, while dense bundles were found in uLMS. Notably, more similarities between reticulin fibers were observed in paired uLMS then paired uADCs. Transcriptomic and multiplex immunofluorescence-based immune profiling showed a higher abundance of T and B cells in primary tumor and in metastatic uADC than uLMS. Moreover, the epigenetic signature of paired samples in uADCs showed more differences than paired samples in uLMS. Some epigenetic variation was also found between the ITF of metastatic uADC and uLMS. Altogether, our data suggest a correlation between morphological and molecular changes at the ITF and the degree of aggressiveness. The use of DP tools for characterizing reticulin scaffolding and immune cell infiltration at the ITF in paired samples together with information provided by omics analyses in a large cohort will hopefully help validate novel biomarkers of tumor aggressiveness, develop new drugs and improve patient quality of life in a much more efficient way.
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Molecular testing of pathognomonic gene fusions is mandatory for small round cell tumor diagnosis, including Ewing sarcoma which is indeed defined by a variety of chimeric genes. Reference laboratories are increasingly implementing NGS-based techniques to overcome several limitations of conventional singleplex determinations. We have been early adopters of a targeted-RNA sequencing method based on Anchored multiplex PCR, which allows assessing several fusion transcripts simultaneously with previous knowledge of only one partner gene. Here we describe in detail our protocol and tips for nucleic acid extraction, library preparation, sequencing, and reporting of gene fusions.
Assuntos
Biomarcadores Tumorais , Neoplasias Ósseas/diagnóstico , Sequenciamento de Nucleotídeos em Larga Escala , Técnicas de Diagnóstico Molecular , Sarcoma de Ewing/diagnóstico , Neoplasias Ósseas/genética , Análise de Dados , Sequenciamento de Nucleotídeos em Larga Escala/métodos , Humanos , Técnicas de Diagnóstico Molecular/métodos , Reação em Cadeia da Polimerase Multiplex , Proteínas de Fusão Oncogênica/genética , Medicina de Precisão/métodos , Reação em Cadeia da Polimerase em Tempo Real , Sarcoma de Ewing/genéticaRESUMO
Risk stratification of solitary fibrous tumor (SFT) patients based on clinicopathological features has limited efficacy, especially in predicting late relapse or metastasis. The hallmark alteration of SFT is the gene fusion NAB2-STAT6, whose prognostic value remains controversial. As biological knowledge of this entity has increased in recent years, new molecular alterations have emerged that could be helpful to refine current risk models. Here, we evaluated NAB2-STAT6 fusion variants and other molecular alterations in a series of 83 SFTs that are enriched in progressing cases. Gene fusion variants were identified by targeted RNA-seq in the whole series, whereas TERT promoter (pTERT) mutations were inspected by Sanger sequencing in a subset of 18 cases. Immunohistochemical assays were performed to assess BCOR and NTRK expression as well as P53 mutation status in 45, 44, and 44 cases, respectively. While confirming the associations of gene fusion variants with clinicopathological parameters, our results do not prove their prognostic value. Pan-TRK immunoexpresion correlated with recurrence/progression, P53 staining associated with higher mitotic counts, and pTERT mutations were enriched in cases with fatal outcome. An intriguing correlation was found for BCOR protein expression with gene fusion variants, size, and tumor location.
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The invasive tumor front (the tumor-host interface) is vitally important in malignant cell progression and metastasis. Tumor cell interactions with resident and infiltrating host cells and with the surrounding extracellular matrix and secreted factors ultimately determine the fate of the tumor. Herein we focus on the invasive tumor front, making an in-depth characterization of reticular fiber scaffolding, infiltrating immune cells, gene expression, and epigenetic profiles of classified aggressive primary uterine adenocarcinomas (24 patients) and leiomyosarcomas (11 patients). Sections of formalin-fixed samples before and after microdissection were scanned and studied. Reticular fiber architecture and immune cell infiltration were analyzed by automatized algorithms in colocalized regions of interest. Despite morphometric resemblance between reticular fibers and high presence of macrophages, we found some variance in other immune cell populations and distinctive gene expression and cell adhesion-related methylation signatures. Although no evident overall differences in immune response were detected at the gene expression and methylation level, impaired antimicrobial humoral response might be involved in uterine leiomyosarcoma spread. Similarities found at the invasive tumor front of uterine adenocarcinomas and leiomyosarcomas could facilitate the use of common biomarkers and therapies. Furthermore, molecular and architectural characterization of the invasive front of uterine malignancies may provide additional prognostic information beyond established prognostic factors.
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Ewing sarcoma is a highly aggressive round cell mesenchymal neoplasm, most often occurring in children and young adults. At the molecular level, it is characterized by the presence of recurrent chromosomal translocations. In the last years, next-generation technologies have contributed to a more accurate diagnosis and a refined classification. Moreover, the application of these novel technologies has highlighted the relevance of intertumoral and intratumoral molecular heterogeneity and secondary genetic alterations. Furthermore, they have shown evidence that genomic features can change as the tumor disseminates and are influenced by treatment as well. Similarly, next-generation technologies applied to liquid biopsies will significantly impact patient management by allowing the early detection of relapse and monitoring response to treatment. Finally, the use of these novel technologies has provided data of great value in order to discover new druggable pathways. Thus, this review provides concise updates on the latest progress of these breakthrough technologies, underscoring their importance in the generation of key knowledge, prognosis, and potential treatment of Ewing Sarcoma.
Assuntos
Sarcoma de Ewing/genética , Animais , Humanos , Biópsia Líquida , Terapia de Alvo Molecular , Fenótipo , Sarcoma de Ewing/diagnóstico , Sarcoma de Ewing/patologiaRESUMO
The transcription factor STAT6 is strongly expressed in various tumours and is most highly expressed in human malignant lymphomas and pancreatic, colorectal, prostate and breast cancers. STAT6 is associated with cancer cell proliferation, an increased malignancy and poor prognosis. Thus, techniques aimed at reducing or blocking STAT6 expression may be useful in treating STAT6high cancers. Among these cancers, colorectal and breast cancers represent two of the most common worldwide and their incidence is increasing every year. In 2018, colorectal and breast cancers represented 10.2% and 11.6% of all new cases of cancer diagnosed, respectively. In this study, four proprietary STAT6 specific small interfering RNA (siRNA) sequences were tested in vitro using the human colon adenocarcinoma cell line, HT-29, and the breast/duct carcinoma cell line, ZR-75-1. Decreases in STAT6 mRNA and protein levels were analysed to confirm the transfection was successful and STAT6 knockdown effects were measured by analysing cell proliferation and apoptosis. Results showed that 100nM siRNA concentration was the most effective and, although all individual sequences were capable of significantly inhibiting cell proliferation, STAT6 siRNA sequences 1 and 4 had the largest effects. STAT6 silencing also significantly induced apoptotic events. In conclusion, these results demonstrate that STAT6 siRNA sequences are capable of inhibiting proliferation of and inducing apoptosis of HT-29 colorectal cancer cells and ZR-75-1 breast cancer cells, halving the number of cancer cells in a short period of time. These experiments will be repeated in other STAT6high cancers in vitro, and animal studies in immunocompromised mice have been planned using xenografts of STAT6-expressing human colorectal and breast cancer cells. The STAT6 siRNA sequences therefore represent a potential treatment for STAT6high colorectal and breast cancers and a wide variety of other STAT6-expressing cancers.
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Apoptose/genética , RNA Interferente Pequeno/genética , Fator de Transcrição STAT6/genética , Linhagem Celular Tumoral , Proliferação de Células , Células Cultivadas , Técnicas de Silenciamento de Genes , Humanos , Interferência de RNA , Fator de Transcrição STAT6/metabolismoRESUMO
Pancreatic and duodenal homeobox 1 (Pdx1) is a transcription factor that regulates the embryonic development of the pancreas and the differentiation toward ß cells. Previously, we have shown that exposure of mouse embryonic stem cells (mESCs) to high concentrations of diethylenetriamine nitric oxide adduct (DETA-NO) triggers differentiation events and promotes the expression of Pdx1. Here we report evidence that Pdx1 expression is associated with release of polycomb repressive complex 2 (PRC2) and P300 from its promoter region. These events are accompanied by epigenetic changes in bivalent markers of histones trimethylated histone H3 lysine 27 (H3K27me3) and H3K4me3, site-specific changes in DNA methylation, and no change in H3 acetylation. On the basis of these findings, we developed a protocol to differentiate mESCs toward insulin-producing cells consisting of sequential exposure to DETA-NO, valproic acid, and P300 inhibitor (C646) to enhance Pdx1 expression and a final maturation step of culture in suspension to form cell aggregates. This small molecule-based protocol succeeds in obtaining cells that express pancreatic ß-cell markers such as PDX1, INS1, GCK, and GLUT2 and respond in vitro to high glucose and KCl.
Assuntos
Diferenciação Celular/efeitos dos fármacos , Epigênese Genética/efeitos dos fármacos , Proteínas de Homeodomínio/metabolismo , Óxido Nítrico/farmacologia , Transativadores/metabolismo , Animais , Linhagem Celular , Metilação de DNA/efeitos dos fármacos , Proteína p300 Associada a E1A/antagonistas & inibidores , Proteína p300 Associada a E1A/genética , Proteína p300 Associada a E1A/metabolismo , Regulação da Expressão Gênica/efeitos dos fármacos , Glucoquinase/metabolismo , Glucose/farmacologia , Transportador de Glucose Tipo 2/metabolismo , Histonas/metabolismo , Proteínas de Homeodomínio/genética , Insulina/metabolismo , Secreção de Insulina , Células Secretoras de Insulina/citologia , Células Secretoras de Insulina/efeitos dos fármacos , Células Secretoras de Insulina/metabolismo , Camundongos , Células-Tronco Embrionárias Murinas/citologia , Células-Tronco Embrionárias Murinas/metabolismo , Complexo Repressor Polycomb 2/genética , Complexo Repressor Polycomb 2/metabolismo , Regiões Promotoras Genéticas , Transativadores/genética , Ácido Valproico/farmacologiaRESUMO
Stem cell pluripotency and differentiation are global processes regulated by several pathways that have been studied intensively over recent years. Nitric oxide (NO) is an important molecule that affects gene expression at the level of transcription and translation and regulates cell survival and proliferation in diverse cell types. In embryonic stem cells NO has a dual role, controlling differentiation and survival, but the molecular mechanisms by which it modulates these functions are not completely defined. NO is a physiological regulator of cell respiration through the inhibition of cytochrome c oxidase. Many researchers have been examining the role that NO plays in other aspects of metabolism such as the cellular bioenergetics state, the hypoxia response and the relationship of these areas to stem cell stemness.
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The reduction of pancreatic ß-cell mass is an important factor in the development of type 1 and type 2 diabetes. Understanding the mechanisms that regulate the maintenance of pancreatic ß-cell mass as well as ß-cell death is necessary for the establishment of therapeutic strategies. In this context, nitric oxide (NO) is a diatomic, gaseous, highly reactive molecule with biological activity that participates in the regulation of pancreatic ß-cell mass. Two types of cellular responses can be distinguished depending on the level of NO production. First, pancreatic ß-cells exposed to inflammatory cytokines, lipid stress or hyperglycaemia produce high concentrations of NO, mainly due to the activation of inducible NO synthase (iNOS), thus promoting cell death. Meanwhile, under homeostatic conditions, low concentrations of NO, constitutively produced by endothelial NO synthase (eNOS), promote cell survival. Here, we will discuss the current knowledge of the NO-dependent mechanisms activated during cellular responses, emphasizing those related to the regulation of cell survival.