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1.
Int J Mol Sci ; 22(21)2021 Nov 04.
Artigo em Inglês | MEDLINE | ID: mdl-34769387

RESUMO

Besides the well-known double-helical conformation, DNA is capable of folding into various noncanonical arrangements, such as G-quadruplexes (G4s) and i-motifs (iMs), whose occurrence in gene promoters, replication origins, and telomeres highlights the breadth of biological processes that they might regulate. Particularly, previous studies have reported that G4 and iM structures may play different roles in controlling gene transcription. Anyway, molecular tools able to simultaneously stabilize/destabilize those structures are still needed to shed light on what happens at the biological level. Herein, a multicomponent reaction and a click chemistry functionalization were combined to generate a set of 31 bis-triazolyl-pyridine derivatives which were initially screened by circular dichroism for their ability to interact with different G4 and/or iM DNAs and to affect the thermal stability of these structures. All the compounds were then clustered through multivariate data analysis, based on such capability. The most promising compounds were subjected to a further biophysical and biological characterization, leading to the identification of two molecules simultaneously able to stabilize G4s and destabilize iMs, both in vitro and in living cells.

2.
Pharmaceutics ; 13(10)2021 Oct 03.
Artigo em Inglês | MEDLINE | ID: mdl-34683905

RESUMO

In the quest for selective G-quadruplex (G4)-targeting chemotypes, natural compounds have been thus far poorly explored, though representing appealing candidates due to the high structural diversity of their scaffolds. In this regard, a unique high diversity in-house library composed of ca. one thousand individual natural products was investigated. The combination of molecular docking-based virtual screening and the G4-CPG experimental screening assay proved to be useful to quickly and effectively identify-out of many natural compounds-five hit binders of telomeric and oncogenic G4s, i.e., Bulbocapnine, Chelidonine, Ibogaine, Rotenone and Vomicine. Biophysical studies unambiguously demonstrated the selective interaction of these compounds with G4s compared to duplex DNA. The rationale behind the G4 selective recognition was suggested by molecular dynamics simulations. Indeed, the selected ligands proved to specifically interact with G4 structures due to peculiar interaction patterns, while they were unable to firmly bind to a DNA duplex. From biological assays, Chelidonine and Rotenone emerged as the most active compounds of the series against cancer cells, also showing good selectivity over normal cells. Notably, the anticancer activity correlated well with the ability of the two compounds to target telomeric G4s.

3.
Int J Mol Sci ; 21(23)2020 Nov 25.
Artigo em Inglês | MEDLINE | ID: mdl-33255744

RESUMO

The transcription factor CCCTC-binding factor (CTCF) modulates pleiotropic functions mostly related to gene expression regulation. The role of CTCF in large scale genome organization is also well established. A unifying model to explain relationships among many CTCF-mediated activities involves direct or indirect interactions with numerous protein cofactors recruited to specific binding sites. The co-association of CTCF with other architectural proteins such as cohesin, chromodomain helicases, and BRG1, further supports the interplay between master regulators of mammalian genome folding. Here, we report a comprehensive LC-MS/MS mapping of the components of the switch/sucrose nonfermentable (SWI/SNF) chromatin remodeling complex co-associated with CTCF including subunits belonging to the core, signature, and ATPase modules. We further show that the localization patterns of representative SWI/SNF members significantly overlap with CTCF sites on transcriptionally active chromatin regions. Moreover, we provide evidence of a direct binding of the BRK-BRG1 domain to the zinc finger motifs 4-8 of CTCF, thus, suggesting that these domains mediate the interaction of CTCF with the SWI/SNF complex. These findings provide an updated view of the cooperative nature between CTCF and the SWI/SNF ATP-dependent chromatin remodeling complexes, an important step for understanding how these architectural proteins collaborate to shape the genome.


Assuntos
Fator de Ligação a CCCTC/genética , Montagem e Desmontagem da Cromatina/genética , Proteínas Cromossômicas não Histona/genética , DNA Helicases/genética , Proteínas Nucleares/genética , Fatores de Transcrição/genética , Dedos de Zinco/genética , Adenosina Trifosfatases/genética , Sítios de Ligação/genética , Proteínas de Ciclo Celular/genética , Regulação da Expressão Gênica/genética , Genoma Humano/genética , Humanos , Complexos Multiproteicos/genética , Mapas de Interação de Proteínas/genética , Espectrometria de Massas em Tandem
4.
Cancers (Basel) ; 12(7)2020 Jul 08.
Artigo em Inglês | MEDLINE | ID: mdl-32650388

RESUMO

Metastatic colorectal cancer (mCRC) remains challenging because of the emergence of resistance mechanisms to anti-epidermal growth factor receptor (EGFR) therapeutics, so more effective strategies to improve the patients' outcome are needed. During the last decade, the application of a multi-omics approach has contributed to a deeper understanding of the complex molecular landscape of human CRC, identifying a plethora of drug targets for precision medicine. Target validation relies on the use of experimental models that would retain the molecular and clinical features of human colorectal cancer, thus mirroring the clinical characteristics of patients. In particular, organoids and patient-derived-xenografts (PDXs), as well as genetically engineered mouse models (GEMMs) and patient-derived orthotopic xenografts (PDOXs), should be considered for translational purposes. Overall, omics and advanced mouse models of cancer represent a portfolio of sophisticated biological tools that, if optimized for use in concert with accurate data analysis, could accelerate the anticancer discovery process and provide new weapons against cancer. In this review, we highlight success reached following the integration of omics and experimental models; moreover, results produced by our group in the field of mCRC are also presented.

5.
J Exp Clin Cancer Res ; 39(1): 111, 2020 Jun 15.
Artigo em Inglês | MEDLINE | ID: mdl-32539869

RESUMO

BACKGROUND: Colorectal cancer is one of most common tumors in developed countries and, despite improvements in treatment and diagnosis, mortality rate of patients remains high, evidencing the urgent need of novel biomarkers to properly identify colorectal cancer high-risk patients that would benefit of specific treatments. Recent works have demonstrated that the telomeric protein TRF2 is over-expressed in colorectal cancer and it promotes tumor formation and progression through extra-telomeric functions. Moreover, we and other groups evidenced, both in vitro on established cell lines and in vivo on tumor bearing mice, that TRF2 regulates the vascularization mediated by VEGF-A. In the present paper, our data evidence a tight correlation between TRF2 and VEGF-A with prognostic relevance in colorectal cancer patients. METHODS: For this study we sampled 185 colorectal cancer patients surgically treated and diagnosed at the Regina Elena National Cancer Institute of Rome and investigated the association between the survival outcome and the levels of VEGF-A and TRF2. RESULTS: Tissue microarray immunohistochemical analyses revealed that TRF2 positively correlates with VEGF-A expression in our cohort of patients. Moreover, analysis of patients' survival, confirmed in a larger dataset of patients from TCGA, demonstrated that co-expression of TRF2 and VEGF-A correlate with a poor clinical outcome in stage I-III colorectal cancer patients, regardless the mutational state of driver oncogenes. CONCLUSIONS: Our results permitted to identify the positive correlation between high levels of TRF2 and VEGF-A as a novel prognostic biomarker for identifying the subset of high-risk colorectal cancer patients that could benefit of specific therapeutic regimens.


Assuntos
Adenocarcinoma/mortalidade , Biomarcadores Tumorais/metabolismo , Neoplasias Colorretais/mortalidade , Cirurgia Colorretal/mortalidade , Recidiva Local de Neoplasia/mortalidade , Proteína 2 de Ligação a Repetições Teloméricas/metabolismo , Fator A de Crescimento do Endotélio Vascular/metabolismo , Adenocarcinoma/metabolismo , Adenocarcinoma/secundário , Adenocarcinoma/cirurgia , Adulto , Idoso , Idoso de 80 Anos ou mais , Neoplasias Colorretais/metabolismo , Neoplasias Colorretais/patologia , Neoplasias Colorretais/cirurgia , Feminino , Seguimentos , Regulação Neoplásica da Expressão Gênica , Humanos , Metástase Linfática , Masculino , Pessoa de Meia-Idade , Invasividade Neoplásica , Recidiva Local de Neoplasia/metabolismo , Recidiva Local de Neoplasia/patologia , Recidiva Local de Neoplasia/cirurgia , Prognóstico , Estudos Retrospectivos , Taxa de Sobrevida
6.
Eur J Pharm Sci ; 149: 105337, 2020 Apr 18.
Artigo em Inglês | MEDLINE | ID: mdl-32311457

RESUMO

The oncogene KRAS is involved in the pathogenesis of many tumors such as pancreatic, lung and colorectal cancers, thereby representing a relevant target for the treatment of these diseases. The KRAS P1 promoter contains a nuclease hypersensitive, guanine-rich sequence able to fold into a G-quadruplex motif (G4). The stabilization of this G4 structure by small molecules is emerging as a feasible approach to downregulate KRAS expression. Here, a set of novel stabilizing molecules was identified through a virtual screening campaign on the NMR structure of the 22-mer KRAS G4. The most promising hits were then submitted to structure-activity relationships studies which allowed improving their binding affinity and selectivity over double helix DNA and different G4 topologies. The best derivative (19) underwent fluorescence titration experiments and further computational studies to disclose its binding mechanism to KRAS G4. Finally, biological assays showed that this compound is capable to reduce the viability of colorectal cancer cells in which mutated KRAS acts as a driver oncogene. Thus, 19 might represent the prototype of a new class of drugs for the treatment of tumors that, expressing mutated forms of KRAS, are refractory to current therapeutic regimens.

7.
Int J Mol Sci ; 21(6)2020 Mar 13.
Artigo em Inglês | MEDLINE | ID: mdl-32183038

RESUMO

A focused library of newly designed monomeric and dimeric naphthalene diimides (NDIs) was analyzed in its ability to recognize specific G-quadruplex (G4) structures discriminating duplex DNA. The best G4 ligands-according to an affinity chromatography-based screening method named G4-CPG-were tested on human cancer and healthy cells, inducing DNA damage at telomeres, and in parallel, showing selective antiproliferative activity on HeLa cancer cells with IC50 values in the low nanomolar range. CD and fluorescence spectroscopy studies allowed detailed investigation of the interaction in solution with different G4 and duplex DNA models of the most promising NDI of the series, as determined by combining the biophysical and biological assays' data.


Assuntos
Antineoplásicos/química , Quadruplex G/efeitos dos fármacos , Iminas/química , Naftalenos/química , Antineoplásicos/farmacologia , Proliferação de Células/efeitos dos fármacos , Dano ao DNA , Células HeLa , Humanos , Iminas/farmacologia , Ligantes , Naftalenos/farmacologia , Telômero/efeitos dos fármacos
8.
Nucleic Acids Res ; 47(18): 9950-9966, 2019 10 10.
Artigo em Inglês | MEDLINE | ID: mdl-31504744

RESUMO

HMGB1 is a ubiquitous non-histone protein, which biological effects depend on its expression and subcellular location. Inside the nucleus, HMGB1 is engaged in many DNA events such as DNA repair, transcription and telomere maintenance. HMGB1 has been reported to bind preferentially to bent DNA as well as to noncanonical DNA structures like 4-way junctions and, more recently, to G-quadruplexes. These are four-stranded conformations of nucleic acids involved in important cellular processes, including telomere maintenance. In this frame, G-quadruplex recognition by specific proteins represents a key event to modulate physiological or pathological pathways. Herein, to get insights into the telomeric G-quadruplex DNA recognition by HMGB1, we performed detailed biophysical studies complemented with biological analyses. The obtained results provided information about the molecular determinants for the interaction and showed that the structural variability of human telomeric G-quadruplex DNA may have significant implications in HMGB1 recognition. The biological data identified HMGB1 as a telomere-associated protein in both telomerase-positive and -negative tumor cells and showed that HMGB1 gene silencing in such cells induces telomere DNA damage foci. Altogether, these findings provide a deeper understanding of telomeric G-quadruplex recognition by HMGB1 and suggest that this protein could actually represent a new target for cancer therapy.


Assuntos
Quadruplex G , Proteína HMGB1/genética , Conformação de Ácido Nucleico , Telômero/genética , DNA/química , DNA/genética , Escherichia coli/genética , Proteína HMGB1/química , Humanos , Telomerase/química , Telomerase/genética , Telômero/química
9.
Genes (Basel) ; 10(9)2019 09 10.
Artigo em Inglês | MEDLINE | ID: mdl-31510074

RESUMO

BRCA1/2 are tumor suppressor genes controlling genomic stability also at telomeric and subtelomeric loci. Their mutation confers a predisposition to different human cancers but also sensitivity to antitumor drugs including poly(ADP-ribose) polymerase (PARP) inhibitors and G-quadruplex stabilizers. Here we demonstrate that BRCA2 deletion triggers TERRA hyperexpression and alternative lengthening mechanisms (ALT) in colon cancer cells in presence of telomerase activity. This finding opens the question if cancer patients bearing BRCA2 germline or sporadic mutation are suitable for anti-telomerase therapies, or how ALT activation could influence the short or long-term response to anti-PARP inhibitors or anti-G-quadruplex therapies.


Assuntos
Proteína BRCA1/genética , Neoplasias do Colo/genética , Homeostase do Telômero , Deleção de Genes , Células HCT116 , Humanos
10.
Nat Commun ; 10(1): 3143, 2019 07 17.
Artigo em Inglês | MEDLINE | ID: mdl-31316060

RESUMO

Heterozygous germline mutations in BRCA2 predispose to breast and ovarian cancer. Contrary to non-cancerous cells, where BRCA2 deletion causes cell cycle arrest or cell death, tumors carrying BRCA2 inactivation continue to proliferate. Here we set out to investigate adaptation to loss of BRCA2 focusing on genome-wide transcriptome alterations. Human cells in which BRCA2 expression is inhibited for 4 or 28 days are subjected to RNA-seq analyses revealing a biphasic response to BRCA2 abrogation. The early, acute response consists of downregulation of genes involved in cell cycle progression, DNA replication and repair and is associated with cell cycle arrest in G1. Surprisingly, the late, chronic response consists predominantly of upregulation of interferon-stimulated genes (ISGs). Activation of the cGAS-STING-STAT pathway detected in these cells further substantiates the concept that BRCA2 abrogation triggers cell-intrinsic immune signaling. Importantly, we find that treatment with PARP inhibitors stimulates the interferon response in cells and tumors lacking BRCA2.


Assuntos
Proteína BRCA2/genética , Neoplasias da Mama/genética , Animais , Neoplasias da Mama/imunologia , Carcinoma Pulmonar de Células não Pequenas/genética , Carcinoma Pulmonar de Células não Pequenas/imunologia , Ciclo Celular/efeitos dos fármacos , Linhagem Celular Tumoral , Neoplasias Colorretais/genética , Neoplasias Colorretais/imunologia , Dano ao DNA , Reparo do DNA , Feminino , Deleção de Genes , Regulação Neoplásica da Expressão Gênica , Humanos , Imunidade Inata , Camundongos SCID , Ftalazinas/farmacologia , Piperazinas/farmacologia
11.
EMBO Mol Med ; 11(7): e9982, 2019 07.
Artigo em Inglês | MEDLINE | ID: mdl-31273933

RESUMO

Due to compromised homologous recombination (HR) repair, BRCA1- and BRCA2-mutated tumours accumulate DNA damage and genomic rearrangements conducive of tumour progression. To identify drugs that target specifically BRCA2-deficient cells, we screened a chemical library containing compounds in clinical use. The top hit was chlorambucil, a bifunctional alkylating agent used for the treatment of chronic lymphocytic leukaemia (CLL). We establish that chlorambucil is specifically toxic to BRCA1/2-deficient cells, including olaparib-resistant and cisplatin-resistant ones, suggesting the potential clinical use of chlorambucil against disease which has become resistant to these drugs. Additionally, chlorambucil eradicates BRCA2-deficient xenografts and inhibits growth of olaparib-resistant patient-derived tumour xenografts (PDTXs). We demonstrate that chlorambucil inflicts replication-associated DNA double-strand breaks (DSBs), similarly to cisplatin, and we identify ATR, FANCD2 and the SNM1A nuclease as determinants of sensitivity to both drugs. Importantly, chlorambucil is substantially less toxic to normal cells and tissues in vitro and in vivo relative to cisplatin. Because chlorambucil and cisplatin are equally effective inhibitors of BRCA2-compromised tumours, our results indicate that chlorambucil has a higher therapeutic index than cisplatin in targeting BRCA-deficient tumours.


Assuntos
Proteína BRCA1/deficiência , Proteína BRCA2/deficiência , Clorambucila/farmacologia , Sistemas de Liberação de Medicamentos , Resistencia a Medicamentos Antineoplásicos/efeitos dos fármacos , Leucemia Linfocítica Crônica de Células B/tratamento farmacológico , Receptores Ativados por Proliferador de Peroxissomo/antagonistas & inibidores , Ftalazinas/farmacologia , Piperazinas/farmacologia , Animais , Linhagem Celular Tumoral , Cricetinae , Resistencia a Medicamentos Antineoplásicos/genética , Humanos , Leucemia Linfocítica Crônica de Células B/genética , Leucemia Linfocítica Crônica de Células B/metabolismo , Masculino , Camundongos , Camundongos SCID , Receptores Ativados por Proliferador de Peroxissomo/metabolismo , Ensaios Antitumorais Modelo de Xenoenxerto
12.
Chemistry ; 25(47): 11085-11097, 2019 Aug 22.
Artigo em Inglês | MEDLINE | ID: mdl-31219221

RESUMO

Naphthalene diimide (NDI) dyads exhibiting a different substitution pattern and linker length have been synthesised and evaluated as G-quadruplex (G4) ligands, by investigating their cytotoxicity in selected cell lines. The dyads with the long C7 linker exhibit extremely low IC50 values, below 10 nm, on different cancer cell lines. Contrary, the dyads with the shorter C4 linker were much less effective, with IC values increasing up to 1 µm. Among the three dyads with the longest linker, small differences in the IC50 values emerge, suggesting that the linker length plays a more important role than the substitution pattern. We have further shown that the dyads are able to induce cellular DNA damage response, which is not limited to the telomeric regions and is likely the origin of their cytotoxicity. Both absorption titration and dynamic light scattering of the most cytotoxic dyads in the presence of hTel22 highlight their ability to induce effective G4 aggregation, acting as non-covalent cross-linking agents.


Assuntos
Dano ao DNA/efeitos dos fármacos , Reparo do DNA/efeitos dos fármacos , Quadruplex G , Imidas/farmacologia , Naftalenos/farmacologia , Linhagem Celular Tumoral , Proliferação de Células/efeitos dos fármacos , Ensaios de Seleção de Medicamentos Antitumorais , Humanos , Imidas/síntese química , Imidas/química , Ligantes , Metáfase/efeitos dos fármacos , Microscopia de Fluorescência , Naftalenos/síntese química , Naftalenos/química , Proteínas Proto-Oncogênicas c-kit/genética , Proteínas Proto-Oncogênicas c-kit/metabolismo , Proteínas Proto-Oncogênicas c-myc/genética , Proteínas Proto-Oncogênicas c-myc/metabolismo , Telômero/efeitos dos fármacos , Telômero/metabolismo
13.
EMBO J ; 38(11)2019 06 03.
Artigo em Inglês | MEDLINE | ID: mdl-31000523

RESUMO

Myeloid-derived suppressor cells (MDSCs) are immature myeloid cells with strong immunosuppressive activity that promote tumor growth. In this study, we describe a mechanism by which cancer cells control MDSCs in human cancers by upregulating TRF2, a protein required for telomere stability. Specifically, we showed that the TRF2 upregulation in cancer cells has extratelomeric roles in activating the expression of a network of genes involved in the biosynthesis of heparan sulfate proteoglycan, leading to profound changes in glycocalyx length and stiffness, as revealed by atomic force microscopy. This TRF2-dependent regulation facilitated the recruitment of MDSCs, their activation via the TLR2/MyD88/IL-6/STAT3 pathway leading to the inhibition of natural killer recruitment and cytotoxicity, and ultimately tumor progression and metastasis. The clinical relevance of these findings is supported by our analysis of cancer cohorts, which showed a correlation between high TRF2 expression and MDSC infiltration, which was inversely correlated with overall patient survival.


Assuntos
Glicocálix/metabolismo , Neoplasias/imunologia , Neoplasias/patologia , Proteína 2 de Ligação a Repetições Teloméricas/fisiologia , Evasão Tumoral/fisiologia , Animais , Células Cultivadas , Feminino , Regulação Neoplásica da Expressão Gênica , Glicocálix/genética , Células HEK293 , Humanos , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Nus , Células Supressoras Mieloides/metabolismo , Células Supressoras Mieloides/fisiologia , Células NIH 3T3 , Neoplasias/genética , Neoplasias/mortalidade , Telômero/metabolismo , Proteína 2 de Ligação a Repetições Teloméricas/genética , Evasão Tumoral/genética
14.
J Exp Clin Cancer Res ; 38(1): 21, 2019 Jan 17.
Artigo em Inglês | MEDLINE | ID: mdl-30654820

RESUMO

Telomeres, the nucleoprotein structures that cap the ends of eukaryotic chromosomes, play important and multiple roles in tumorigenesis. Functional telomeres need the establishment of a protective chromatin structure based on the interplay between the specific complex named shelterin and a tight nucleosomal organization. Telomere shortening in duplicating somatic cells leads eventually to the destabilization of the telomere capping structure and to the activation of a DNA damage response (DDR) signaling. The final outcome of this process is cell replicative senescence, which constitute a protective barrier against unlimited proliferation. Cells that can bypass senescence checkpoint continue to divide until a second replicative checkpoint, crisis, characterized by chromosome fusions and rearrangements leading to massive cell death by apoptosis. During crisis telomere dysfunctions can either inhibit cell replication or favor tumorigenesis by the accumulation of chromosomal rearrangements and neoplastic mutations. The acquirement of a telomere maintenance mechanism allows fixing the aberrant phenotype, and gives the neoplastic cell unlimited replicative potential, one of the main hallmarks of cancer.Despite the crucial role that telomeres play in cancer development, little is known about the epigenetic alterations of telomeric chromatin that affect telomere protection and are associated with tumorigenesis. Here we discuss the current knowledge on the role of telomeric chromatin in neoplastic transformation, with a particular focus on H3.3 mutations in alternative lengthening of telomeres (ALT) cancers and sirtuin deacetylases dysfunctions.


Assuntos
Cromatina/genética , Variação Genética , Neoplasias/genética , Telômero/genética , Animais , Transformação Celular Neoplásica/genética , Transformação Celular Neoplásica/metabolismo , Cromatina/metabolismo , Dano ao DNA , Epigênese Genética , Heterocromatina/genética , Heterocromatina/metabolismo , Humanos , Neoplasias/metabolismo , Neoplasias/patologia , Neoplasias/terapia , Sirtuínas/metabolismo , Homeostase do Telômero/genética
15.
Nucleic Acids Res ; 47(7): 3365-3382, 2019 04 23.
Artigo em Inglês | MEDLINE | ID: mdl-30698737

RESUMO

The telomeric protein TRF2 is overexpressed in several human malignancies and contributes to tumorigenesis even though the molecular mechanism is not completely understood. By using a high-throughput approach based on the multiplexed Luminex X-MAP technology, we demonstrated that TRF2 dramatically affects VEGF-A level in the secretome of cancer cells, promoting endothelial cell-differentiation and angiogenesis. The pro-angiogenic effect of TRF2 is independent from its role in telomere capping. Instead, TRF2 binding to a distal regulatory element promotes the expression of SULF2, an endoglucosamine-6-sulfatase that impairs the VEGF-A association to the plasma membrane by inducing post-synthetic modification of heparan sulfate proteoglycans (HSPGs). Finally, we addressed the clinical relevance of our findings showing that TRF2/SULF2 expression is a worse prognostic biomarker in colorectal cancer (CRC) patients.


Assuntos
Neoplasias do Colo/metabolismo , Sulfotransferases/genética , Proteína 2 de Ligação a Repetições Teloméricas/metabolismo , Microambiente Tumoral , Fator A de Crescimento do Endotélio Vascular/metabolismo , Animais , Linhagem Celular Tumoral , Neoplasias do Colo/irrigação sanguínea , Neoplasias do Colo/patologia , Proteoglicanas de Heparan Sulfato/química , Proteoglicanas de Heparan Sulfato/metabolismo , Heparina/metabolismo , Humanos , Masculino , Camundongos , Camundongos Nus , Metástase Neoplásica , Neovascularização Patológica , Sulfatases , Sulfotransferases/biossíntese , Proteína 2 de Ligação a Repetições Teloméricas/deficiência , Ensaios Antitumorais Modelo de Xenoenxerto
16.
Eur J Med Chem ; 163: 295-306, 2019 Feb 01.
Artigo em Inglês | MEDLINE | ID: mdl-30529547

RESUMO

A focused library of analogs of a lead-like G-quadruplex (G4) targeting compound (4), sharing a furobenzoxazine naphthoquinone core and differing for the pendant groups on the N-atom of the oxazine ring, has been here analyzed with the aim of developing more potent and selective ligands. These molecules have been tested vs. topologically different G4s by the G4-CPG assay, an affinity chromatography-based method for screening putative G4 ligands. The obtained results showed that all these compounds were able to bind several G4 structures, both telomeric and extra-telomeric, thus behaving as multi-target ligands, and two of them fully discriminated G4 vs. duplex DNA. Biological assays proved that almost all the compounds produced effective DNA damage, showing marked antiproliferative effects on tumor cells in the low µM range. Combined analysis of the G4-CPG binding assays and biological data led us to focus on compound S4-5, proved to be less cytotoxic than the parent compound 4 on normal cells. An in-depth biophysical characterization of the binding of S4-5 to different G4s showed that the here identified ligand has higher affinity for the G4s and higher ability to discriminate G4 vs. duplex DNA than 4. Molecular docking studies, in agreement with the NMR data, suggest that S4-5 interacts with the accessible grooves of the target G4 structures, giving clues for its increased G4 vs. duplex selectivity.


Assuntos
Desenho de Fármacos , Quadruplex G/efeitos dos fármacos , Sítios de Ligação , Proliferação de Células/efeitos dos fármacos , Cromatografia de Afinidade , Dano ao DNA , Humanos , Ligantes , Naftoquinonas/química , Naftoquinonas/farmacologia , Oxazinas/química , Oxazinas/farmacologia , Ligação Proteica , Relação Estrutura-Atividade
17.
Cell Death Dis ; 9(10): 996, 2018 09 24.
Artigo em Inglês | MEDLINE | ID: mdl-30250025

RESUMO

Sirtuin 6 (SIRT6) is a member of the NAD+-dependent class III deacetylase sirtuin family, which plays a key role in cancer by controlling transcription, genome stability, telomere integrity, DNA repair, and autophagy. Here we analyzed the molecular and biological effects of UBCS039, the first synthetic SIRT6 activator. Our data demonstrated that UBCS039 induced a time-dependent activation of autophagy in several human tumor cell lines, as evaluated by increased content of the lipidated form of LC3B by western blot and of autophagosomal puncta by microscopy analysis of GFP-LC3. UBCS039-mediated activation of autophagy was strictly dependent on SIRT6 deacetylating activity since the catalytic mutant H133Y failed to activate autophagy. At the molecular level, SIRT6-mediated autophagy was triggered by an increase of ROS levels, which, in turn, resulted in the activation of the AMPK-ULK1-mTOR signaling pathway. Interestingly, antioxidants were able to completely counteract UBCS039-induced autophagy, suggesting that ROS burst had a key role in upstream events leading to autophagy commitment. Finally, sustained activation of SIRT6 resulted in autophagy-related cell death, a process that was markedly attenuated using either a pan caspases inhibitor (zVAD-fmk) or an autophagy inhibitor (CQ). Overall, our results identified UBCS039 as an efficient SIRT6 activator, thereby providing a proof of principle that modulation of the enzyme can influence therapeutic strategy by enhancing autophagy-dependent cell death.


Assuntos
Autofagia/efeitos dos fármacos , Ativação Enzimática , Neoplasias/metabolismo , Neoplasias/patologia , Pirróis/farmacologia , Quinoxalinas/farmacologia , Sirtuínas/metabolismo , Proteínas Quinases Ativadas por AMP/metabolismo , Acetilação/efeitos dos fármacos , Apoptose/efeitos dos fármacos , Autofagossomos/metabolismo , Proteína Homóloga à Proteína-1 Relacionada à Autofagia/metabolismo , Ciclo Celular , Proliferação de Células , Células HCT116 , Células HeLa , Histonas/metabolismo , Humanos , Peptídeos e Proteínas de Sinalização Intracelular/metabolismo , Pirróis/síntese química , Quinoxalinas/síntese química , Espécies Reativas de Oxigênio/metabolismo , Transdução de Sinais/efeitos dos fármacos
18.
J Exp Clin Cancer Res ; 37(1): 57, 2018 Mar 13.
Artigo em Inglês | MEDLINE | ID: mdl-29534749

RESUMO

Developing drugs that target KRAS, the most frequently mutated oncogene in cancer, has not been successful despite much concerted efforts dedicated towards it in the last thirty years. Considering the key role this driver oncogene plays, the pharmacological drugging of KRAS remains a key challenge for cancer research. In this review, we highlight the emerging experimental strategies for blocking KRAS function and signaling and its direct targeting. We also report on the results in this field of research produced by our group.


Assuntos
Antineoplásicos/farmacologia , Biomarcadores Tumorais , Neoplasias Colorretais/metabolismo , Neoplasias Colorretais/patologia , Terapia de Alvo Molecular , Proteínas Proto-Oncogênicas p21(ras)/antagonistas & inibidores , Animais , Antineoplásicos/uso terapêutico , Neoplasias Colorretais/tratamento farmacológico , Neoplasias Colorretais/genética , Resistencia a Medicamentos Antineoplásicos/efeitos dos fármacos , Resistencia a Medicamentos Antineoplásicos/genética , Receptores ErbB/antagonistas & inibidores , Receptores ErbB/genética , Receptores ErbB/metabolismo , Regulação Neoplásica da Expressão Gênica/efeitos dos fármacos , Humanos , Terapia de Alvo Molecular/métodos , Mutação , Proteínas Proto-Oncogênicas p21(ras)/genética , Proteínas Proto-Oncogênicas p21(ras)/metabolismo , Interferência de RNA , Transdução de Sinais/efeitos dos fármacos
19.
J Exp Clin Cancer Res ; 36(1): 189, 2017 12 22.
Artigo em Inglês | MEDLINE | ID: mdl-29273061

RESUMO

Telomeres are specialized nucleoprotein structures responsible for protecting chromosome ends in order to prevent the loss of genomic information. Telomere maintenance is required for achieving immortality by neoplastic cells. While most cancer cells rely on telomerase re-activation for linear chromosome maintenance and sustained proliferation, a significant population of cancers (10-15%) employs telomerase-independent strategies, collectively referred to as Alternative Lengthening of Telomeres (ALT). ALT mechanisms involve different types of homology-directed telomere recombination and synthesis. These processes are facilitated by loss of the ATRX or DAXX chromatin-remodeling factors and by abnormalities of the telomere nucleoprotein architecture. Although the functional consequences of telomerase and ALT up-regulation are similar in that they both prevent overall telomere shortening in tumors, these telomere maintenance mechanisms (TMMs) differ in several aspects which may account for their differential prognostic significance and response to therapy in various tumor types. Therefore, reliable methods for detecting telomerase activity and ALT are likely to become an important pre-requisite for the use of treatments targeting one or other of these mechanisms. However, the question whether ALT presence can confer sensitivity to rationally designed anti-cancer therapies is still open. Here we review the latest discoveries in terms of mechanisms of ALT activation and maintenance in human tumors, methods for ALT identification in cell lines and human tissues and biomarkers validation. Then, original results on sensitivity to rational based pre-clinical and clinical anti-tumor drugs in ALT vs hTERT positive cells will be presented.


Assuntos
Antineoplásicos Alquilantes/farmacologia , Dioxóis/farmacologia , Neoplasias/patologia , Homeostase do Telômero/efeitos dos fármacos , Telômero/efeitos dos fármacos , Tetra-Hidroisoquinolinas/farmacologia , Humanos , Neoplasias/genética , Trabectedina
20.
EMBO Mol Med ; 9(10): 1398-1414, 2017 10.
Artigo em Inglês | MEDLINE | ID: mdl-28729482

RESUMO

Maintenance of genome integrity requires the functional interplay between Fanconi anemia (FA) and homologous recombination (HR) repair pathways. Endogenous acetaldehyde, a product of cellular metabolism, is a potent source of DNA damage, particularly toxic to cells and mice lacking the FA protein FANCD2. Here, we investigate whether HR-compromised cells are sensitive to acetaldehyde, similarly to FANCD2-deficient cells. We demonstrate that inactivation of HR factors BRCA1, BRCA2, or RAD51 hypersensitizes cells to acetaldehyde treatment, in spite of the FA pathway being functional. Aldehyde dehydrogenases (ALDHs) play key roles in endogenous acetaldehyde detoxification, and their chemical inhibition leads to cellular acetaldehyde accumulation. We find that disulfiram (Antabuse), an ALDH2 inhibitor in widespread clinical use for the treatment of alcoholism, selectively eliminates BRCA1/2-deficient cells. Consistently, Aldh2 gene inactivation suppresses proliferation of HR-deficient mouse embryonic fibroblasts (MEFs) and human fibroblasts. Hypersensitivity of cells lacking BRCA2 to acetaldehyde stems from accumulation of toxic replication-associated DNA damage, leading to checkpoint activation, G2/M arrest, and cell death. Acetaldehyde-arrested replication forks require BRCA2 and FANCD2 for protection against MRE11-dependent degradation. Importantly, acetaldehyde specifically inhibits in vivo the growth of BRCA1/2-deficient tumors and ex vivo in patient-derived tumor xenograft cells (PDTCs), including those that are resistant to poly (ADP-ribose) polymerase (PARP) inhibitors. The work presented here therefore identifies acetaldehyde metabolism as a potential therapeutic target for the selective elimination of BRCA1/2-deficient cells and tumors.


Assuntos
Acetaldeído/metabolismo , Proteína BRCA1/metabolismo , Proteína BRCA2/metabolismo , Rad51 Recombinase/metabolismo , Aldeído-Desidrogenase Mitocondrial/genética , Aldeído-Desidrogenase Mitocondrial/metabolismo , Animais , Proteína BRCA1/genética , Proteína BRCA2/genética , Linhagem Celular Tumoral , Dano ao DNA , Anemia de Fanconi/genética , Proteína do Grupo de Complementação D2 da Anemia de Fanconi/genética , Proteína do Grupo de Complementação D2 da Anemia de Fanconi/metabolismo , Fibroblastos , Recombinação Homóloga , Humanos , Camundongos , Camundongos Nus , Rad51 Recombinase/genética , Ensaios Antitumorais Modelo de Xenoenxerto
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