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J Phys Chem B ; 123(34): 7365-7371, 2019 Aug 29.
Artigo em Inglês | MEDLINE | ID: mdl-31365827


The behavior of the structural parameters of DNA considering different levels of methylation in CpG islands is studied by means of full-atom molecular dynamics simulations and electronic circular dichroism, both in an artificial model system and in a gene promoter sequence. It is demonstrated that methylation although intrinsically brings quite local perturbations may, if its level is high enough, induce cooperative effects that strongly modify the DNA backbone torsional parameters altering the helicity as compared to the nonmethylated case. Because methylation of the CpG island is correlated with the regulation of gene expression, understanding the structural modifications induced in DNA is crucial to characterize all the fine equilibria into play in epigenetics phenomena.

Sci Rep ; 7(1): 8885, 2017 08 21.
Artigo em Inglês | MEDLINE | ID: mdl-28827702


Nonsteroidal 2-arylproprionic acids are widely used, over-the-counter, anti-inflammatory drugs. Photosensitivity is a commonly overlooked adverse effect of these drugs. Based on the combined use of cell viability assays and molecular modeling, we prove and rationalize the photochemical pathways triggering photosensitization for two drugs, ibuprofen and ketoprofen. As its parent compound benzophenone, ketoprofen produces singlet oxygen, upon triplet manifold population. However, ibuprofen and ketoprofen photodissociate and hence may generate two highly reactive radicals. The formation of metastable aggregates between the two drugs and B-DNA is also directly probed by molecular dynamics. Our approach characterizes the coupled influence of the drug's intrinsic photochemistry and the interaction pattern with DNA. The photosensitization activity of nonsteroidal 2-arylproprionic acids, being added to gels and creams for topical use, should be crucially analyzed and rationalized to enact the proper preventive measures.

Morte Celular/efeitos dos fármacos , Morte Celular/efeitos da radiação , Ibuprofeno/farmacologia , Cetoprofeno/farmacologia , Fármacos Fotossensibilizantes/farmacologia , Raios Ultravioleta , Apoptose/efeitos dos fármacos , Linhagem Celular Tumoral , Sobrevivência Celular/efeitos dos fármacos , Sinergismo Farmacológico , Humanos , Ibuprofeno/química , Cetoprofeno/química , Modelos Moleculares , Estrutura Molecular , Fármacos Fotossensibilizantes/química , Relação Estrutura-Atividade , Raios Ultravioleta/efeitos adversos
Sci Rep ; 6: 28480, 2016 06 22.
Artigo em Inglês | MEDLINE | ID: mdl-27329409


We report a molecular modeling study, coupled with spectroscopy experiments, on the behavior of two well known organic dyes, nile blue and nile red, when interacting with B-DNA. In particular, we evidence the presence of two competitive binding modes, for both drugs. However their subsequent photophysical behavior is different and only nile blue is able to induce DNA photosensitization via an electron transfer mechanism. Most notably, even in the case of nile blue, its sensitization capabilities strongly depend on the environment resulting in a single active binding mode: the minor groove. Fluorescence spectroscopy confirms the presence of competitive interaction modes for both sensitizers, while the sensitization via electron transfer, is possible only in the case of nile blue.

DNA de Forma B/química , Oxazinas/química , Fármacos Fotossensibilizantes/química , Sítios de Ligação , Ligação Competitiva , Simulação por Computador , Transporte de Elétrons , Corantes Fluorescentes/química , Modelos Moleculares , Conformação de Ácido Nucleico , Processos Fotoquímicos , Polidesoxirribonucleotídeos/química , Espectrometria de Fluorescência , Espectrofotometria
Front Chem ; 3: 67, 2015.
Artigo em Inglês | MEDLINE | ID: mdl-26734600


We report the characterization of the interaction between B-DNA and three terpyridin iron II complexes. Relatively long time-scale molecular dynamics (MD) is used in order to characterize the stable interaction modes. By means of molecular modeling and UV-vis spectroscopy, we prove that they may lead to stable interactions with the DNA duplex. Furthermore, the presence of larger π-conjugated moieties also leads to the appearance of intercalation binding mode. Non-covalent stabilizing interactions between the iron complexes and the DNA are also characterized and evidenced by the analysis of the gradient of the electronic density. Finally, the structural deformations induced on the DNA in the different binding modes are also evidenced. The synthesis and chemical characterization of the three complexes is reported, as well as their absorption spectra in presence of DNA duplexes to prove the interaction with DNA. Finally, their effects on human cell cultures have also been evidenced to further enlighten their biological effects.

Cancer Res ; 73(16): 5040-52, 2013 Aug 15.
Artigo em Inglês | MEDLINE | ID: mdl-23774208


The DNA repair protein damaged DNA-binding 2 (DDB2) has been implicated in promoting cell-cycle progression by regulating gene expression. DDB2 is selectively overexpressed in breast tumor cells that are noninvasive, but not in those that are invasive. We found that its overexpression in invasive human breast tumor cells limited their motility and invasiveness in vitro and blocked their ability to colonize lungs in vivo, defining a new function for DDB2 in malignant progression. DDB2 overexpression attenuated the activity of NF-κB and the expression of its target matrix metalloprotease 9 (MMP9). Mechanistic investigations indicated that DDB2 decreased NF-κB activity by upregulating expression of IκBα by binding the proximal promoter of this gene. This effect was causally linked to invasive capacity. Indeed, knockdown of DDB2-induced IκBα gene expression restored NF-κB activity and MMP9 expression, along with the invasive properties of breast tumor cells overexpressing DDB2. Taken together, our findings enlighten understanding of how breast cancer cells progress to an invasive phenotype and underscore potential clinical interest in DDB2 as a prognostic marker or therapeutic target in this setting.

Neoplasias da Mama/metabolismo , Neoplasias da Mama/patologia , Proteínas de Ligação a DNA/genética , Proteínas de Ligação a DNA/metabolismo , NF-kappa B/genética , Biomarcadores Tumorais/genética , Biomarcadores Tumorais/metabolismo , Neoplasias da Mama/genética , Linhagem Celular Tumoral , Movimento Celular/genética , Feminino , Humanos , Proteínas I-kappa B/genética , Proteínas I-kappa B/metabolismo , Células MCF-7 , Metaloproteinase 9 da Matriz/genética , Metaloproteinase 9 da Matriz/metabolismo , Inibidor de NF-kappaB alfa , NF-kappa B/metabolismo , Invasividade Neoplásica , Prognóstico , Regiões Promotoras Genéticas , Transcrição Genética , Regulação para Cima/genética
Free Radic Biol Med ; 50(12): 1771-9, 2011 Jun 15.
Artigo em Inglês | MEDLINE | ID: mdl-21419216


A high basal expression of manganese superoxide dismutase (MnSOD) has been reported in aggressive breast cancer cells, according to an unknown mechanism, and contributes to their invasive abilities. Here, we report the involvement of Sp1 and nuclear factor-κB (NF-κB) transcription factors in this high basal expression of MnSOD in aggressive breast cancer cells. Suppression or inactivation of Sp1 showed that it plays an essential role in the high MnSOD expression in aggressive breast cancer cells through a unique binding site identified by chromatin immunoprecipitation (ChIP) assay and functional analysis of the MnSOD proximal promoter. Treatment of cells with a specific NF-κB inhibitor peptide decreased significantly high basal MnSOD expression. A ChIP assay showed binding of a constitutive p50/p65 NF-κB complex to the MnSOD intronic enhancer element, associated with hyperacetylation of the H3 histone. Finally, high basal expression of MnSOD resulted in the lack of expression of Damaged DNA binding 2 (DDB2) protein in aggressive breast cancer cells. DDB2 overexpression prevented the binding of Sp1 as well as of NF-κB to their respective elements on the MnSOD gene. These results contribute to a better understanding of MnSOD up-regulation, which may be clinically important in the prediction of breast tumor progression.

Neoplasias da Mama/genética , Proteínas de Ligação a DNA/metabolismo , NF-kappa B/genética , NF-kappa B/metabolismo , Fator de Transcrição Sp1/metabolismo , Superóxido Dismutase/genética , Acetilação , Sequência de Bases , Neoplasias da Mama/metabolismo , Neoplasias da Mama/patologia , Linhagem Celular Tumoral , Elementos Facilitadores Genéticos , Feminino , Radicais Livres , Histonas/genética , Histonas/metabolismo , Humanos , Dados de Sequência Molecular , Regiões Promotoras Genéticas , Estudos Retrospectivos , Fator de Transcrição Sp1/genética , Superóxido Dismutase/biossíntese , Superóxido Dismutase/metabolismo , Fatores de Transcrição/genética , Fatores de Transcrição/metabolismo , Regulação para Cima