Publications by authors named "Robert Dante"

Mammalian cytosine DNA methylation (5mC) is associated with the integrity of the genome and the transcriptional status of nuclear DNA. Due to technical limitations, it has been less clear if mitochondrial DNA (mtDNA) is methylated and whether 5mC has a regulatory role in this context. Here, we used bisulfite-independent single-molecule sequencing of native human and mouse DNA to study mitochondrial 5mC across different biological conditions.

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Article Synopsis
  • Aging is a significant risk factor for cancer, yet its relationship with the phospholipase A2 receptor (PLA2R1), which influences cellular senescence, remains underexplored.
  • In experiments with old PLA2R1 knockout mice, researchers found these mice were more likely to develop tumors and had higher levels of PARP1, a key player in DNA repair, suggesting a link between PLA2R1 and tumor suppression.
  • The study indicates that PLA2R1 acts to prevent aging-related tumors by inhibiting PARP1 through a reactive oxygen species-Rb signaling pathway, thereby promoting DNA damage responses that help suppress cancer development.
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Abnormal DNA methylation has been described in human inflammatory conditions of the gastrointestinal tract, such as inflammatory bowel disease (IBD). As other complex diseases, IBD results from the balance between genetic predisposition and environmental exposures. As such, DNA methylation may be the consequence (and potential effector) of both, genetic susceptibility variants and/or environmental signals such as cytokine exposure.

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The Sonic Hedgehog (SHH) pathway plays a key role in cancer. Alterations of SHH canonical signaling, causally linked to tumor progression, have become rational targets for cancer therapy. However, Smoothened (SMO) inhibitors have failed to show clinical benefit in patients with cancers displaying SHH autocrine/paracrine expression.

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In human tumours, the crosstalk between cancer cells and their microenvironment is involved in tumour progression, metastasis and resistance to anti-cancer therapies. Among the factors involved in this exchange of information pro-inflammatory cytokines seem to play a crucial role. We observed that a group of pro-inflammatory cytokines, interleukin 6 (IL6), interleukin 1-beta (IL1b), and tumour necrosis factor-alpha (TNFa), preferentially activated genes exhibiting a high basal methylation level at their transcription start sites, in the human breast cancer cell line MCF7.

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In a number of human cancers, NTN1 upregulation inhibits apoptosis induced by its so-called dependence receptors DCC and UNC5H, thus promoting tumor progression. In other cancers however, the selective inhibition of this dependence receptor death pathway relies on the silencing of pro-apoptotic effector proteins. We show here that a substantial fraction of human breast tumors exhibits simultaneous DNA methylation-dependent loss of expression of NTN1 and of DAPK1, a serine threonine kinase known to transduce the netrin-1 dependence receptor pro-apoptotic pathway.

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Netrin-1 has been shown to be up-regulated in a fraction of human cancers as a mechanism to allow these tumors to escape the pro-apoptotic activity of some of its main dependence receptors, the UNC5 homologs (UNC5H). Here we identify the V-2 domain of netrin-1 to be important for its interaction with the Ig1/Ig2 domains of UNC5H2. We generate a humanized anti-netrin-1 antibody that disrupts the interaction between netrin-1 and UNC5H2 and triggers death of netrin-1-expressing tumor cells in vitro.

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DNA methylation is thought to induce transcriptional silencing through the combination of two mechanisms: the repulsion of transcriptional activators unable to bind their target sites when methylated, and the recruitment of transcriptional repressors with specific affinity for methylated DNA. The Methyl CpG Binding Domain proteins MeCP2, MBD1 and MBD2 belong to the latter category. Here, we present MBD2 ChIPseq data obtained from the endogenous MBD2 in an isogenic cellular model of oncogenic transformation of human mammary cells.

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Loss of secreted phospholipase A2 receptor (PLA2R1) has recently been found to render human primary cells more resistant to senescence whereas increased PLA2R1 expression is able to induce cell cycle arrest, cancer cell death or blockage of cancer cell transformation in vitro, suggesting that PLA2R1 displays tumor suppressive activities. Here we report that PLA2R1 expression strongly decreases in samples of human renal cell carcinoma (RCC). Knockdown of PLA2R1 increases renal cancer cell tumorigenicity supporting a role of PLA2R1 loss to promote in vivo RCC growth.

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In cancer cells, methylation-dependent gene silencing is at least partly mediated by the "Methyl-CpG-Binding Domain protein 2" (MBD2 protein), via the recruitment of chromatin remodeling complexes. However this repressive role was poorly investigated in normal cells. To identify the genes repressed by MBD2 in these cells, we have determined the impact of MBD2 depletion on gene expression in human embryonic MRC5 fibroblasts, using RNA inference combined with microarray analysis.

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Methyl-CpG Binding Domain (MBD) proteins are thought to be key molecules in the interpretation of DNA methylation signals leading to gene silencing through recruitment of chromatin remodeling complexes. In cancer, the MBD-family member, MBD2, may be primarily involved in the repression of genes exhibiting methylated CpG at their 5' end. Here we ask whether MBD2 randomly associates methylated sequences, producing chance effects on transcription, or exhibits a more specific recognition of some methylated regions.

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Introduction: Persistent human papillomavirus (HPV) infection is the primary causal agent in the development of the uterine cervix carcinoma. Nevertheless, only a minority of high-risk HPV-associated lesions progress to cervical cancer, suggesting involvement of other molecular alterations. Among putative changes, aberrant methylation might be a crucial event.

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Aberrant DNA methylation is an early event in carcinogenesis and could serve as an additional molecular marker for the early diagnosis. The study was performed to investigate the promoter methylation of DAPK1, CDH13, and TWIST1 genes in uterine cervix lesions in an effort to examine whether this epigenetic event is involved in the process of cervical carcinogenesis, and whether it might be used as a molecular marker of cervical lesions. We conducted a retrospective study of 60 uterine cervix specimens, including 8 normal tissue samples, 10 benign lesions, 28 precancerous lesions (CIN1-3), and 14 squamous cell carcinomas (SCC).

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Background: In human Estrogen Receptor alpha (ERalpha)-positive breast cancers, 5' end dense methylation of the estrogen-regulated pS2/TFF1 gene correlates with its transcriptional inhibition. However, in some ERalpha-rich biopsies, pS2 expression is observed despite the methylation of its TATA-box region. Herein, we investigated the methylation-dependent mechanism of pS2 regulation.

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Human telomerase reverse transcriptase (hTERT) is expressed in most cancer cells. Paradoxically, its promoter is embedded in a hypermethylated CpG island. A short region escapes to this alteration, allowing a basal level of transcription.

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The quantification of BRCA1 messenger RNA molecules by a quantitative competitive one-step reverse transcriptase polymerase chain reaction method indicates that BRCA1 is upregulated both in human male and female germ cells and in preimplantation embryos. Because BRCA1 is involved in several pathways that participate in preserving intact chromosome and genome integrity, these data suggest that BRCA1 dysfunction might alter human embryogenesis or fertility.

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The methyl-CpG binding domain (MBD) proteins are key molecules in the interpretation of DNA methylation signals leading to gene silencing. We investigated their binding specificity at the constitutively methylated region of a CpG island containing the bidirectional promoter of the Breast cancer predisposition gene 1, BRCA1, and the Near BRCA1 2 (NBR2) gene. In HeLa cells, quantitative chromatin immunoprecipitation assays indicated that MBD2 is associated with the methylated region, while MeCP2 and MBD1 were not detected at this locus.

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SLC5A8, proposed as a thyroid apical iodide transporter, was recently defined as a Na+-coupled transporter of short-chain fatty acid. To document the expression pattern of SLC5A8 in the thyroid, we analyzed the regulation of its expression in normal human thyrocytes in culture and in tissues with distinct functional activity. To determine whether SLC5A8 expression is altered in all thyroid carcinomas or only in particular subtypes, we investigated the level of its expression in a series of 50 hypofunctioning tumors.

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In the vertebrate genome, methylation of deoxycytosine residues of CpGs dinucleotide has been associated with transcriptional silencing of genes, parental imprinting, X-inactivation and chromatin remodelling. In human somatic tissues, the 5' end of the BRCA1 CpG island is methylated, whereas this region is unmethylated in mature germ cells and early embryos. In gametes, as in somatic tissues, the CpG sites in the coding region are methylated.

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During the last years, a direct link between DNA methylation and repressive chromatin structure has been established. This structural modification is mediated by histone deacetylases targeted to the methylated sequences by Methyl Binding Proteins (MBD). Human cancer cells exhibit both a global hypomethylation and some localized hypermethylations suggesting that the deregulation of the methylation machinery is a central event in tumorigenesis.

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