In mammals, the correct spatio-temporal patterns of gene expression are coordinated by transcription factor networks in combination with epigenetic signalling pathways. CpG methylation is an epigenetic modification of DNA involved in the heritable transmission of gene silencing patterns. Increasing evidence suggest a primary role for CpG methylation in the direct regulation of gene expression, at least for a subset of promoters. An example of this direct regulation is represented by the ectopic expression of genes involved in genome defence pathways upon global loss of methylation. However, the mechanistic relationship between CpG methylation and transcriptional regulation is not well understood. To explore this, we have applied Cap Analysis of Gene Expression (CAGE), to cells deficient in CpG methylation (Mouse Embryonic Fibroblasts with hypomorphic mutation of Dnmt1 ) and matched controls. This provides a quantitative, single nucleotide resolution, genome wide map of methylation responsive transcription initiation. Integrating this with RNA-seq, genome wide measures of CpG methylation and ChIP-seq for histone modifications in the same system, provides a detailed view of how reduced CpG methylation alters the chromatin and transcriptional landscape of the genome. Our results show dramatic shifts in the cellular RNA pool, with the pronounced up-regulation or de-repression of promoters in a specific sub-family of transposable elements. Tens of other genic and non-coding RNA promoters similarly show dramatic inductions. Contrary to a prior hypothesis, we found no evidence for increased rates of transcriptional initiation from anonymous genomic sites not previously implicated in promoter activity. Transcription initiation at CpG island promoters is generally unaffected by hypomethylation, however a set of TSSs located in CpG island shores and a class to transposable element overlapping TSSs do appear to be sensitive to methylation and are significantly up-regulated upon hypomethylation.

Background: Hyperhomocysteinemia (HHcy) is an established risk factor for thrombotic diseases yet the underlying mechanism remain unclear. In this study we investigated the effect of HHcy on endothelial cell-platelet interaction and its role in thrombosis. Methods and Results: We used a novel mouse model of HHcy (plasma homocysteine, Hcy 80 micromolar) in which a Zn2+ inducible human cystathionine beta-synthase (CBS) transgene was introduced to circumvent the neonatal lethality of the Cbs gene deficiency (Tg-hCBS Cbs-/- mice). Hcy-lowering therapy was performed by giving ZnSO4 water to induce human CBS transgene expression in adult mice. Thrombus formation was examined by photo dye-induced cremaster microvasculature thrombosis using intravital microscopy, in which endothelium was preserved, and by FeCl3-induced carotid artery thrombosis, which denudated the endothelium. HHcy accelerated cremaster arteriolar thrombosis and decreased blood flow cessation time from 41.8 min in control mice to 30.5 min in TghCBS Cbs-/- mice. Venular blood flow cessation time was slightly decreased from 5.6 to 5.0 min. Hcy-lowering therapy reduced Hcy level from 80 micromolar to 6.8 micromolar after 2 weeks of ZnSO4 water and prolonged arteriolar blood cessation time from 30.5 to 37.8 min. Interestingly, FeCl3-induced carotid artery thrombosis did not change the occlusion time. Hcy did not potentiate the aggregation and secretion function in washed human platelets from healthy donor treated with Hcy (50, 100 micromolar) or from Tg-hCBS Cbs-/- mice. However, inter-cellular adhesion molecule 1 (ICAM-1) levels, but not vascular adhesion molecule 1 (VCAM-1), were increased in cremaster tissues from Tg-hCBS Cbs-/- mice by western blot. In cultured human umbilical vein ECs (HUVEC), Hcy (100 micromolar, 24h) promoted human platelet adhesion by 200% in static adhesion assay. Using western blot, FACS and RT-PCR, we found that Hcy increased protein and mRNA levels of ICAM-1, but not that of VCAM-1, in HUVEC. ICAM-1 blocking antibody partially reversed Hcy increased platelets adhesion to HUVEC. Hcy induced ICAM-1 expression and reduced DNA methylation on ICAM-1 promoter, which were mimicked by DNA methyltransferase inhibitor azacytidine, and histone deacetylase inhibitors sodium butyrate and trichostatin A. Hcy treatment also increased intracellular Hcy, Sadenosylhomocysteine (SAH) accumulation and decreased SAM/SAH ratio in HUVECs. Hcy decreased methyl CpG binding protein 2 (MeCP2) binding and increased acetylated histone H3 (AcH3) binding to ICAM-1 core promoter region using chromatin immunoprecipitation. Pyrosequencing of ICAM-1 core promoter and adjacent region shows a decreased DNA methylation by Hcy treatment. In high methionine diet-induce HHcy in WT and Icam-/- mice, Icam-/- mice fed with HM diet only show moderately accelerated venular and barely accelerated arteriolar occlusion time compared with WT mice with CT diet using photo dye-induced thrombosis model. Conclusion: HHcy accelerates arteriolar thrombosis and increases EC-platelet interaction via ICAM-1 induction partially through DNA hypomethylation. / Pharmacology

Hyperhomocysteinemia (HHcy) is an independent risk factor for cardiovascular disease (CVD). We previously demonstrated that homocysteine (Hcy) suppresses endothelial cell (EC) proliferation, migration, and post-injury EC repair, but the molecular mechanism underlying Hcy-induced EC injury is unclear. In this study, we identified a novel gene, Carom, which mediates Hcy-induced suppression of EC migration and angiogenesis. We identified FCH and double SH3 domains 2 (FCHSD2), a novel gene, as an Hcy-responsive gene through Differential Display in Hcy (50µM)-treated human umbilical vein endothelial cells (HUVEC). FCHSD2 was initially named as Carom, based on the identification of this molecule as an interacting protein of calcium/calmodulin-dependent serine protein kinase (CASK) and membrane associated guanylate kinase, WW and PDZ domain containing 1 (MAGI1). In this thesis, we describe this gene as Carom. Carom belongs to the Fes/CIP4 homology and Bin/amphiphysin/Rvs (F-BAR) protein family, which is a group of multivalent adaptors linking plasma membrane and cytoskeleton, involved in endocytosis and cell migration. However, Carom's function is poorly characterized. Based on the findings that CASK and MAGI1 inhibit cell migration and growth, and the role of F-BAR proteins in cell migration, we hypothesize that Hcy up-regulates Carom to inhibit EC growth and/or migration, finally leading to CVD. We confirmed the significant induction of Carom mRNA expression in Hcy-treated HUVECs or human aortic endothelial cells (HAEC) by Northern blot and Real-time PCR. In addition, we found that Carom protein expressions were significantly increased both in Hcy-treated HAECs and lung ECs isolated from HHcy mice by Western blot using our homemade rabbit antibody against Carom. These data indicate that Hcy increases endothelial expression of Carom both in vitro and in vivo. Furthermore, in order to characterize Carom function in EC, we generated recombinant adenovirus Adv-Carom to transduce Carom for gain-of-function study and Adv-Carom-shRNA to express Carom shRNA for loss-of-function study. We found that neither adenovirus-transduced Carom expression nor adenoviral Carom shRNA had any impact on HUVEC proliferation by using [3H]-thymidine incorporation. Interestingly, we demonstrated that Adv-Carom inhibited HAEC migration, while Hcy-induced HEAC migration inhibition could be rescued by Adv-Carom-shRNA. These data suggest that Carom may inhibit angiogenesis via a cell proliferation-independent mechanism. Furthermore, we found that Hcy significantly increased the intracellular level of S-adenosyl homocysteine (SAH) but not S-adenosyl methionine (SAM), and decreased the SAM/SAH ratio, an indicator of cellular methylation, in HAECs, by using High-performance liquid chromatography/electrospray tandem mass spectrometry (HPLC-MS) to measure SAH and SAM levels. Meanwhile, Carom protein expression was significantly induced by azacytidine (AZC), a DNA methyltransferse inhibitor, in a dose-dependent manner in HAECs. Based on these data, we speculated that Hcy-induced hypomethylation could associate with Carom up-regulation. Thus we used bisulfite deep sequencing to profile methylation status of Carom gene in Hcy-treated HUVECs and found that Carom promoter was hypomethylated by Hcy. In addition, eight transcriptional factor binding sites on Carom were hypomethylated by Hcy. These data suggest that Hcy may induce Carom via a DNA hypomethylation-dependent mechanism. Moreover, we found that adenovirus-transduced Carom expression significantly increased the secretions of two anti-angiogenic chemokines, CXCL10 and CXCL11 in HAECs by using human cytokine array. Similarly, Hcy also significantly increased mRNA expressions of CXCL10 and CXCL11, while Adv-Carom-shRNA blocked down the inductions of CXCL10 and CXCL11 by Hcy. We further demonstrated that adenovirus-transduced Carom expression inhibited angiogenesis by performing tube formation assay of HAECs, whereas Hcy-induced angiogenesis suppression were rescued by Adv-Carom-shRNA as well as the neutralizing antibodies of CXCL10 and CXCL11. These data suggest that Hcy induces Carom to trigger CXCL10 and CXCL11 downstream to inhibit angiogenesis. In conclusion, Hcy induces Carom expression through DNA hypomethylation to inhibit EC migration and angiogenesis. / Pharmacology

Submitted by Fabio Sobreira Campos da Costa (fabio.sobreira@ufpe.br) on 2016-03-30T13:52:07Z No. of bitstreams: 2 license_rdf: 1232 bytes, checksum: 66e71c371cc565284e70f40736c94386 (MD5) Tese_Adriana_Bispo_final_ficha catalografica.pdf: 4400523 bytes, checksum: b3e9eb79c58483144a4659be5ab2d45c (MD5) / Made available in DSpace on 2016-03-30T13:52:07Z (GMT). No. of bitstreams: 2 license_rdf: 1232 bytes, checksum: 66e71c371cc565284e70f40736c94386 (MD5) Tese_Adriana_Bispo_final_ficha catalografica.pdf: 4400523 bytes, checksum: b3e9eb79c58483144a4659be5ab2d45c (MD5) Previous issue date: 2015-09-15 / A síndrome de Turner (ST) é caracterizada primariamente pelo cariótipo 45,X, mas podem ocorrer linhagens celulares incluindo o cromossomo Y. A precisa identificação do cromossomo Y nessas pacientes é de grande importância clínica devido a um aumento no risco de tumores gonadais. A alta frequência de mosaicismo na ST faz dessa síndrome um importante modelo para investigação do efeito dos polimorfismos dos genes da rota do folato como fatores de risco à não disjunção cromossômica somática. Alterações no metabolismo do folato podem promover aneuploidias por um efeito indireto sobre os padrões de metilação do DNA. Neste trabalho reportamos a frequência de mosaicismo críptico do cromossomo Y e sua associação clínica, como também a descrição de uma alteração cromossômica rara. Adicionalmente, foi investigada uma possível associação entre os polimorfismos de genes da rota do folato e o risco de não disjunção cromossômica somática na ST. A presença de mosaicismo oculto do cromossomo Y foi detectada em 2,7% dos casos, os quais mostraram genitália feminina normal sem sinais de virilização ou desenvolvimento tumoral. Assim, a busca de sequências do Y deve ser realizada na ST independente do cariótipo e/ou sinais clínicos. Não foi possível estabelecer uma associação entre os polimorfismos dos genes MTHFR, MTR, RFC1 e TYMS, independentes ou combinados, modulando o risco de não disjunção somática na ST, demostrando que polimorfismos nesses genes, envolvidos na rota do folato, podem não representar uma importante contribuição para os mecanismos de geração das aneuploidias. / Turner syndrome (TS) is primarily characterized by the 45,X karyotype, but can occur cell lines including the Y-chromosome. The precise identification of Y-chromosome in TS patients is of great clinical importance due to an increased risk of gonadal tumors. The high frequency of mosaicism in TS makes this syndrome an important model to investigate the effect of genetic polymorphisms in folate pathway as risk factors to somatic non-disjunction. Changes in folate metabolism can promote aneuploidies by an indirect effect on the DNA methylation patterns. In this work was reported the frequency of Y-chromosome hidden mosaicism and its clinical association, and also described a rare chromosomal alteration. Additionally, a possible association between gene polymorphisms in folate pathway and the risk of somatic chromosome non-disjunction in TS was investigated. The presence of hidden Y chromosome mosaicism was detected in 2.7% of cases, which showed normal female genitalia without signs virilization or tumor development. Thus, the search for Y sequences should be held at TS regardless of the karyotypes and/or clinical signs. We could not establish an association between polymorphisms of MTHFR, MTR, RFC1 and TYMS genes, independent or combined, modulating the risk of somatic non-disjunction in TS, showing that polymorphisms in these genes, involved in folate metabolism, may not represent an important contribution to the generation mechanisms of aneuploidies.

No description available.

Homocysteine-Methionine (HM) cycle produces a universal methyl group donor S-adenosylmethionine (SAM), a competitive methylation inhibitor S-adenosylhomocysteine (SAH), and an intermediate amino acid product homocysteine (Hcy). Elevated plasma levels of Hcy is termed as hyperhomocycteinemia (HHcy) which is an established risk factor for cardiovascular disease (CVD) and neural degenerative disease. We were the first to describe methylation inhibition as a mediating biochemical mechanism for endothelial injury and inflammatory monocyte differentiation in HHcy-related CVD and diabetes. We proposed metabolism-associated danger signal (MADS) recognition as a novel mechanism for metabolic risk factor-induced inflammatory responses, independent from pattern recognition receptor (PRR)-mediated pathogen-associated molecular pattern (PAMP)/danger-associated molecular pattern (DAMP) recognition. In this study, we examined the relationship of HM cycle gene expression with methylation regulation in human disease. We selected 115 genes in the extended HM cycle, including 31 metabolic enzymes and 84 methyltransferases (MT), examined their mRNA levels in 35 human disease conditions using a set of public databases. We discovered that: 1) HM cycle senses metabolic risk factor and controls SAM/SAH-dependent methylation. 2) Most of metabolic enzymes in HM cycle (8/11) are located in cytosol, while most of the SAM-dependent MTs (61/84) are located in the nucleus, and Hcy metabolism is absent in the nucleus. 3) 11 up-regulated, 3 down-regulated and 24 differentially regulated SAM/SAH-responsive signal pathways are involved in 7 human disease categories. 4) 8 SAM/SAH-responsive H3/H4 hypomethylation sites are identified in 8 disease conditions. We conclude that HM cycle is a key metabolic sensor system which mediates receptor-independent MADS recognition and modulates SAM/SAH-dependent methylation in human disease. We propose that HM metabolism takes place in cytosol and that nuclear methylation equilibration requires nuclear-cytosol transfer of SAM, SAH and Hcy. CD40 is a cell surface molecule which is expressed on antigen presenting cells such as monocyte, macrophage, dendritic cells and neutrophils. The costimulatory pair, CD40 and CD40L, enhances T cell activation and induce chronic inflammatory disease. Also, DNA hypomethylation on CD40 promotor induces inflammatory monocyte differentiation in chronic kidney disease. In order to figure out if CD40 is a prototypic HM cycle regulated master gene, RNA-seq analysis were performed for CD40+ and CD40- monocytes from mouse peripheral blood and 1,093 differentially expressed genes (DEGs) were selected from those two groups. All the DEGs modulate as much as 15 functional gene groups such as cytokines, enzymes and transcriptional factors. Furthermore, CD40+ monocytes activated trained immunity pathways especially in Acetyl-CoA generation and mevalonate pathway. In HM cycle, CD40 is a prototypic HM cycle regulated master gene to induce the most of the Hcy metabolic enzymes as well as MT, which can further modulate the methylation-regulated pathological signaling. / Biomedical Sciences

ABSTRACT Hepatocellular carcinoma (HCC) is one of the most prevalent cancers in Taiwan. The development of hepatocellular carcinoma is a multi-step process associated with alterations in genes expression such as activation of oncogenes and inactivation of tumor suppressor genes. Mutation/deletion of tumor suppressor gene p53 occurs in 40-50% HCC. Moreover, patients with p53 inactivation have significantly shorter survival after surgery. Inactivation of p53 leads to chromosome instability and may alter expression of its downstream target genes including 14-3-3s for cell cycle arrest or PUMA for apoptosis induction. In this thesis study, we employed five human hepatoma cell lines and ten surgical HCC samples containing paired normal and tumor tissues to investigate 14-3-3s and PUMA expression during liver carcinogenesis. Quantitative reverse transcription-polymerase chain reaction (qRT-PCR) revealed that 14-3-3s mRNA expression was detected in well and poorly differentiated hepatoma cells except Mahlavu cells. Western blot analysis further validated such finding that 14-3-3s protein is not detectable in Mahlavu cell. In human surgical HCC tissues, qRT-PCR showed that 14-3-3s mRNA was elevated in 90% of HCC tissues. Western blot analysis indicated that 14-3-3s protein level was increased in 60% of HCC tissues. Finally, immunohistochemical analysis revealed that 14-3-3s was up-regulated in 50% of HCC tissues comparing with their adjacent non-tumor tissues. Together, these results indicated that 14-3-3s expression was up-regulated in HCC. qRT-PCR and western blot analysis indicated that PUMA mRNA and protein levels were decreased in human and rat hepatoma cells. In human surgical HCC tissues, qRT-PCR showed that PUMA mRNA was reduced in 60% of HCC tissues. Western blot analysis indicated that PUMA protein level was decreased in 100 of HCC tissues. Finally, immunohistochemical analysis revealed that PUMA was down-regulated in 70% of HCC tissues comparing with their adjacent non-tumor tissues. Together, these results indicated that PUMA expression was down-regulated in HCC. In the future, large-scale analysis using more HCC samples will be required to delineate the correlation of 14-3-3s/PUMA expression with clinical parameters of HCC.

Myelodysplastic syndrome (MDS) is a heterogeneous group of clonal hematopoietic stem cell disorders with ineffective hematopoiesis. It is characterized by morphological dysplasia, peripheral cytopenias affecting one or more cell lineages and an increased risk of transformation into acute myeloid leukemia (AML). The early stages of MDS can be considered a premalignant disease. The pathogenesis of MDS has not been fully explained yet, but due to the development of molecular genetic and cytogenetic methods, the origin and development of the disease is gradually being elucidated. In addition to the cytogenetic changes that are part of the prognostic system (IPSS-R), the somatic mutations found in different genes come to the forefront of interest. However, they are not routinely used in clinical practice. One of the objectives of this study was monitoring of mutations in TP53 gene in lower-risk MDS patients who generally have a good prognosis and for whom these findings have a particularly relevant prognostic significance. We investigated a total of 154 patients with lower-risk MDS, and 13% of them had a mutation. After dividing patients according to the presence of del(5q), we observed significant differences in the incidence of the mutations. The mutations were detected in 23.6% of patients with...

Les cellules placentaires portent un génome différent du génome maternel, puisque 50% de leurs gènes proviennent du génome paternel. Cependant, comme les cellules cancéreuses après la transformation néoplasique, elles réussissent à envahir les tissus de leur hôte, échapper à son système immunitaire et induire une angiogenèse afin d’établir la grossesse. Les cellules cancéreuses et placentaires arborent aussi une différence majeure : alors que de tels mécanismes typiques des cancers sont incontrôlés dans les cellules cancéreuses, ils sont spatialement et temporairement contrôlés dans les cellules placentaires saines. Ainsi, le recherche sur le « concept cancer/placenta » – l’utilisation du placenta pour mieux comprendre le cancer – peut aboutir à l’identification de biomarqueurs et d’approches thérapeutiques innovantes en oncologie, tout comme en gynécologie-obstétrique. Par exemple, les efforts de recherche portant sur l’expression des gènes CGB, codant pour la sous-unité ß de l’hormone chorionique gonadotrope humaine, dans les cellules cancéreuses et placentaires a mené au développement d’un biomarqueur largement utilisé pour la prise en charge de multiples cancers. Il est aussi intéressant de noter que ce même biomarqueur est aussi utilisé pour le dépistage d’aneuploïdies fœtales. De même, le clonage d’INSL4, codant pour le précurseur du peptide placentaire précoce ressemblant à l’insuline (pro-EPIL), dans des cellulaires placentaires précoces, a mené au développement d’un biomarqueur faisant actuellement l’objet d’études cliniques. Avec l’émergence de l’épigénétique, des études de la méthylation de l’ADN, la caractéristique épigénétique la mieux comprise, ont montré que les loci de gènes CGB et INSL4 sont hypométhylés dans les cellules cancéreuses et placentaires ; ce qui pourrait refléter l’hypométhylation globale caractéristique de ces deux types cellulaires. Par conséquent, le projet doctoral présenté dans cette thèse a exploré les modifications des paysages épigénétiques des cellules placentaires au cours de la grossesse et des cellules cancéreuses au cours de la transformation néoplasique. Ce projet a contribué initialement au développement d’un test d’immunoanalyse qui détecte l’hCGß de type II, spécialement codée par un sous-groupe de gènes CGB et détectée dans le sérum de patients atteints de cancers non-placentaires et de trisomie 21 fœtale. Ce test d’immunoanalyse, avec un test similaire développé pour la détection de pro-EPIL, a aussi été utilisé pour des études de preuve de concept précoces quant à l’effet de la méthylation de l’ADN sur l’expression de l’hCGß de type II et de pro-EPIL dans des surnageants de culture cellulaire. En fin de compte, ce projet a mené à la première comparaison directe et pan-génomique de la méthylation de l’ADN dans des cellules cancéreuses au cours de la transformation néoplasique et dans des cellulaires placentaires au cours de la grossesse. Cette étude a porté sur des données, disponibles publiquement, générées à partir de biopsies de 13 types de tumeurs, de villosités choriales (tissus placentaires) et d’autres tissus sains. Elle a également porté sur des données originales générées par nos soins à partir d’échantillons placentaires uniques : des cellules cytotrophoblastiques isolées de villosités choriales ex vivo. Toutes les données inclus dans cette étude ont été générées sur une plateforme de puces à ADN pour la mesure de la méthylation au niveau de 485 512 sites CpG pour chaque échantillon. En combinant, des logiciels innovants reposant sur la puissance d’algorithmes de lissage statistique et sur un solide rationnel biologique, cette étude a ainsi contribué à l’identification de motifs d’hypométhylation à l’échelle du mégabase distinguant les cellules placentaires du début de la grossesse de celles de la fin de la grossesse tout comme ils distinguent les cellules cancéreuses des cellules normales. (...) / Placental cells carry a genome different from the maternal genome, as 50% of it originate from the paternal genome. However, like cancer cells after neoplastic transformation, they successfully invade their host tissues, escape its immune system and induce angiogenesis in order to establish the pregnancy. Cancer and placental cells also display a major discrepancy: while such hallmarks of cancer mechanisms are uncontrolled in cancer cells, they are spatially and temporally controlled in healthy placental cells. Thus, research on the “cancer/placenta concept” – the use of the placenta to better understand cancer – can lead to innovative biomarkers and therapeutic approaches in oncology as well as in gynecology and obstetrics. For example, research efforts on the expression of the CGB genes, encoding for the human chorionic gonadotropin beta subunit (hCGß), in cancer and placental cells have led to the development of a biomarker widely used for the management of various cancers. Interestingly, this same biomarker is also used for the screening of fetal aneuploidies. Likewise, the cloning of INSL4, encoding for the precursor of the early placenta insulin-like peptide (pro-EPIL) in early pregnancy placental cells, has led to the development of a biomarker currently investigated in the clinical setting. Following the rise of epigenetic, studies on DNA methylation, the most well understood epigenetic mark, showed that the loci of CGB genes and INSL4 are hypomethylated in cancer and placental cells, which may reflect a global hypomethylation also characteristic of these cells. Therefore, the doctoral project presented in this dissertation had explored modifications in the epigenetic landscape of placental cells throughout pregnancy and cancer cells throughout neoplastic transformation. This project initially contributed to the development of an immunoassay detecting type II hCGß, specifically encoded by a subset of CGB genes and detected in the serum of patients with non-placental cancers and fetal Down Syndrome. This immunoassay, along with another one directed to pro-EPIL, was also used for an early proof of concept study regarding the effect of DNA methylation on the expression of type II hCGß and pro-EPIL in cell culture supernatants. Ultimately, this project led to the first direct genome-wide comparison of DNA methylation in cancer cells throughout neoplastic transformation and in placental cells throughout pregnancy. It included publically available data generated from biopsies of 13 types of tumors, chorionic villi (placental tissues) and other normal tissues. It also included original data generated from unique placental samples: villous cytotrophoblastic cells isolated ex vivo from chorionic villi. All datasets were generated on a microarray platform measuring DNA methylation at 485,512 CpG sites in each sample. Combining innovative software that leverages the power of statistical smoothing algorithms and a strong biological rationale, this study thus contributed to the identification of megabase-scale patterns of hypomethylation distinguishing early pregnancy from late pregnancy placenta cells as they distinguish normal from cancers cells. Strikingly, the affected genomic regions encompassed genes related to hallmarks of cancer mechanisms such as epithelial-mesenchymal transition (EMT), innate and acquired immune response, and hypoxia. Taken together, these results suggest the hypothesis that patterns of DNA methylation might contribute to “cancer/placenta epigenetic switches” allowing placental implantation and neoplastic transformation when turned “on”, while preventing the placenta to degenerate into an aggressive tumor when turned “off”.