RESUMO
Over-consumption of iron-rich red meat and hereditary or genetic iron overload are associated with increased risk of colorectal carcinogenesis, yet the mechanistic basis of how metal-mediated signaling leads to oncogenesis remains enigmatic. Using fresh colorectal cancer (CRC) samples we identify Pirin, an iron sensor, that overcomes a rate-limiting step in oncogenesis, by re-activating the dormant human-reverse-transcriptase (hTERT) subunit of telomerase holoenzyme in an iron-(Fe3+)-dependent-manner and thereby drives CRCs. Chemical genetic screens combined with isothermal-dose response fingerprinting and mass-spectrometry identified a small molecule SP2509, that specifically inhibits Pirin-mediated hTERT reactivation in CRCs by competing with iron-(Fe3+) binding. Our findings, first to document how metal ions reactivate telomerase, provide a molecular mechanism for the well-known association between red meat, and increased incidence of CRCs. Small molecules like SP2509 represent a novel modality to target telomerase that acts as driver of 90% human cancers and is yet to be targeted in clinic.
RESUMO
Reactivation of telomerase is a major hallmark observed in 90% of all cancers. Yet paradoxically, enhanced telomerase activity does not correlate with telomere length and cancers often possess short telomeres; suggestive of supplementary non-canonical roles that telomerase might play in the development of cancer. Moreover, studies have shown that aberrant expression of shelterin proteins coupled with their release from shortening telomeres can further promote cancer by mechanisms independent of their telomeric role. While targeting telomerase activity appears to be an attractive therapeutic option, this approach has failed in clinical trials due to undesirable cytotoxic effects on stem cells. To circumvent this concern, an alternative strategy could be to target the molecules involved in the non-canonical functions of telomeric proteins. In this review, we will focus on emerging evidence that has demonstrated the non-canonical roles of telomeric proteins and their impact on tumorigenesis. Furthermore, we aim to address current knowledge gaps in telomeric protein functions and propose future research approaches that can be undertaken to achieve this.
Assuntos
Neoplasias/patologia , Proteínas de Ligação a Telômeros/metabolismo , Proteínas de Ciclo Celular/genética , Proteínas de Ciclo Celular/metabolismo , Disceratose Congênita/genética , Disceratose Congênita/patologia , Humanos , Neoplasias/metabolismo , Proteínas Nucleares/genética , Proteínas Nucleares/metabolismo , Regiões Promotoras Genéticas , Ribonucleoproteínas Nucleolares Pequenas/genética , Ribonucleoproteínas Nucleolares Pequenas/metabolismo , Telomerase/genética , Telomerase/metabolismo , Telômero/metabolismo , Proteínas de Ligação a Telômeros/química , Proteínas rap1 de Ligação ao GTP/genética , Proteínas rap1 de Ligação ao GTP/metabolismoRESUMO
The telomerase holoenzyme, which has a highly conserved role in maintaining telomere length, has long been regarded as a high-profile target in cancer therapy due to the high dependency of the majority of cancer cells on constitutive and elevated telomerase activity for sustained proliferation and immortality. In this review, we present the salient findings in the telomerase field with special focus on the association of telomerase with inflammation and cancer. The elucidation of extra-telomeric roles of telomerase in inflammation, reactive oxygen species (ROS) generation, and cancer development further complicated the design of anti-telomerase therapy. Of note, the discovery of the unique mechanism that underlies reactivation of the dormant telomerase reverse transcriptase TERT promoter in somatic cells not only enhanced our understanding of the critical role of TERT in carcinogenesis but also opens up new intervention ideas that enable the differential targeting of cancer cells only. Despite significant effort invested in developing telomerase-targeted therapeutics, devising efficacious cancer-specific telomerase/TERT inhibitors remains an uphill task. The latest discoveries of the telomere-independent functionalities of telomerase in inflammation and cancer can help illuminate the path of developing specific anti-telomerase/TERT therapeutics against cancer cells.
Assuntos
Inflamação/enzimologia , Neoplasias/enzimologia , Telomerase/metabolismo , Animais , Humanos , Estresse OxidativoRESUMO
Tissue macrophages arise during embryogenesis from yolk-sac (YS) progenitors that give rise to primitive YS macrophages. Until recently, it has been impossible to isolate or derive sufficient numbers of YS-derived macrophages for further study, but data now suggest that induced pluripotent stem cells (iPSCs) can be driven to undergo a process reminiscent of YS-hematopoiesis in vitro. We asked whether iPSC-derived primitive macrophages (iMacs) can terminally differentiate into specialized macrophages with the help of growth factors and organ-specific cues. Co-culturing human or murine iMacs with iPSC-derived neurons promoted differentiation into microglia-like cells in vitro. Furthermore, murine iMacs differentiated in vivo into microglia after injection into the brain and into functional alveolar macrophages after engraftment in the lung. Finally, iPSCs from a patient with familial Mediterranean fever differentiated into iMacs with pro-inflammatory characteristics, mimicking the disease phenotype. Altogether, iMacs constitute a source of tissue-resident macrophage precursors that can be used for biological, pathophysiological, and therapeutic studies.
Assuntos
Técnicas de Cultura de Células/métodos , Hematopoese , Macrófagos/fisiologia , Neurônios/fisiologia , Células-Tronco Pluripotentes/fisiologia , Animais , Diferenciação Celular , Células Cultivadas , Embrião de Mamíferos , Humanos , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Transgênicos , NeurogêneseRESUMO
Induced pluripotent stem cells (iPSCs) offer great promise as tools for basic biomedical research, disease modeling, and drug screening. In this chapter, we describe the generation of patient-specific, transgene-free iPSCs from skin biopsies and peripheral blood mononuclear cells through electroporation of episomal vectors and growth under two different culture conditions. The resulting iPSC lines are characterized with respect to pluripotency marker expression through immunostaining, tested for transgene integration by PCR, and assayed for differentiation capacity via teratoma formation.
Assuntos
Técnicas de Cultura de Células/métodos , Reprogramação Celular , Fibroblastos/citologia , Células-Tronco Pluripotentes Induzidas/citologia , Leucócitos Mononucleares/citologia , Amidas/farmacologia , Animais , Biomarcadores/metabolismo , Biópsia , Diferenciação Celular/efeitos dos fármacos , Colágeno/química , Criopreservação , Combinação de Medicamentos , Eletroporação , Inibidores Enzimáticos/farmacologia , Fibroblastos/efeitos dos fármacos , Fibroblastos/metabolismo , Expressão Gênica , Vetores Genéticos/química , Vetores Genéticos/metabolismo , Humanos , Células-Tronco Pluripotentes Induzidas/efeitos dos fármacos , Células-Tronco Pluripotentes Induzidas/metabolismo , Peptídeos e Proteínas de Sinalização Intercelular/farmacologia , Laminina/química , Leucócitos Mononucleares/efeitos dos fármacos , Leucócitos Mononucleares/metabolismo , Camundongos , Plasmídeos/genética , Plasmídeos/metabolismo , Cultura Primária de Células , Proteoglicanas/química , Piridinas/farmacologia , Pele/citologia , Pele/metabolismo , Teratoma/genética , Teratoma/metabolismo , Teratoma/patologia , TransgenesRESUMO
Physalis species are used in folk medicine for phytotherapeutic properties. The extracts of medicinal plants are known to possesscytotoxic and chemopreventative compounds. In this study we investigated antibacterial, antioxidant, DNA damage preventativeproperties of Physalis peruviana (golden berry) on leaf and shoot ethanol extracts and their effects on cytotoxicity of HeLa cellsand expression of apoptotic pathway genes. Among the tested bacteria for antibacterial activity, maximum inhibition zone wasdetermined in Lactococcus lactis. The phenolic content was found higher in leaf extracts than shoot extracts. The antioxidantactivity showed the highest TEAC values of the leaf (2 mg/mL) and the shoot (0.5 mg/mL) extracts as 0.291±0.04 and 0.192±0.015,respectively. In DNA damage prevention assay both leaf and shoot extracts, especially 30 and 20 µg/mL concentrations, exhibitedsignificant protection against DNA damage-induced by hydroxyl radical generated by Fenton reaction. Our results suggest thatleaf and shoot extracts possess cytotoxic effect on HeLa cells when applied as 100 µg/mL concentration. Also mRNA expressionanalysis showed the alteration of antiapoptotic genes, so the results suggest that P. peruviana ethanol extracts induce apoptoticcell death and should be investigated for identification of active compounds and their mechanisms of action.