No / This volume highlights recent studies identifying epigenetic mechanisms as essential regulators of skin development, stem cell activity and regeneration. Chapters are contributed by leading experts and promote the skin as an accessible model system for studying mechanisms that control organ development and regeneration. The discussions contained throughout are of broad relevance to other areas of biology and medicine and can help inform the development of novel therapeutics for skin disorders as well as new approaches to skin regeneration that target the epigenome. Part of the highly successful Stem Cells and Regenerative Medicine series, Epigenetic Regulation of Skin Development and Regeneration uncovers the fundamental significance of epigenetic mechanisms in skin development and regeneration, and emphasizes the development of new therapies for a number of skin disorders, such as pathological conditions of epidermal differentiation, pigmentation and carcinogenesis. At least six categories of researchers will find this book essential, including stem cell, developmental, hair follicle or molecular biologists, and gerontologists or clinical dermatologists.

Epigenetic changes represent chemical modifications of the DNA molecule and histone proteins by which gene expression is altered. Among them, DNA methylation is a known mechanism of silencing of tumor-suppressor and DNA repair genes, with an important role in carcinogenesis. Many studies have been done in order to identify the methylation signatures of these genes in different types of cancer. In our study, we investigated the methylation status of promoter regions of eight mismatch repair genes (MLH1, MSH2, MSH3, MLH3, PMS1, PMS2, MSH6 and EXO1) in 45 sporadic colorectal cancer cases and 12 head and neck cancer patients. Two out of eight genes, MLH1 and MLH3, exhibited promoter methylation. The results from both groups of patients were concordant. We summarize that the methylation profiles of MLH1 and MLH3 promoters could be potential candidates for epigenetic biomarkers in colorectal cancer, and eventually in head and neck cancer. Further investigations, which would confirm this theory, should be carried out.

A combinação de agentes quimiopreventivos com diferentes mecanismos de ação tem sido considerada uma estratégia promissora para a prevenção do câncer. Dentre os diversos compostos bioativos em alimentos, destacam-se a tributirina, um pró-fármaco do ácido butírico presente em laticínios e produzido pela fermentação de fibras dietéticas, e o óleo de linhaça, fonte de ácido alfa linolênico. Nesse contexto, foi avaliada a atividade quimiopreventiva de lipídios estruturados obtidos a partir da interesterificação enzimática de tributirina e óleo de linhaça durante a fase de promoção inicial da hepatocarcinogênese experimental. Ratos Wistar machos submetidos ao modelo do hepatócito resistente receberam diariamente, por via intragástrica (i.g), maltodextrina, óleo de linhaça, tributirina, a mistura não esterificada ou lipídios estruturados durante a fase de promoção inicial. O tratamento com lipídios estruturados demonstrou atividade quimiopreventiva comparável à da tributirina, mesmo resultando em menor concentração hepática de ácido butírico. Tanto a tributirina quanto os lipídios estruturados não inibiram a proliferação celular em lesões preneoplásicas, mas induziram a apoptose naquelas em remodelação. Os efeitos inibitórios da tributirina em fases iniciais da hepatocarcinogênese experimental estão relacionados ao aumento da acetilação de histonas e à modulação de processos de translocação nuclear da p53. No presente estudo, foi observado aumento substancial da razão nuclear/citoplasmática de p53 e importina-alfa em fígados de animais submetidos ao modelo e tratados com tributirina, mas não nos tratados com lipídios estruturados. Por outro lado, o tratamento com lipídios estruturados reduziu a expressão dos oncogenes Bcl2, Ccnd2, Pdgfa, Vegfa e aumentou a expressão dos genes supressores de tumor Cdh13, Fhit e Socs3. Assim, embora o potencial quimiopreventivo dos lipídios estruturados seja comparável ao da tributirina, os resultados sugerem que o novo composto não exibe atividade de HDACi, e que seus efeitos inibitórios na hepatocarcinogênese possam ser atribuídos à modulação da expressão de oncogenes e genes supressores de tumor. / Combination of chemopreventive agents with different mechanisms of action has been considered a promising strategy to cancer prevention. Among several bioactive food compounds, tributyrin, a butyric acid prodrug obtained from dairy products and dietetic fiber fermentation, and flax seed oil, a rich source of alpha linolenic acid have shown chemopreventive potential. Here, we evaluated the chemopreventive activity of structured lipids obtained by enzymatic interesterification of tributyrin and flax seed oil during the early promotion phase of experimental hepatocarcinogenesis. Male Wistar rats subjected to the resistant hepatocyte model were treated daily, i.g, with maltodextrin, flax seed oil, tributyrin, non-sterified blend, or structured lipids. Treatment structured lipids showed similar chemopreventive activity compared to tributyrin, even when structured lipids yielded lower concentrations of butyric in the liver. Tributyrin and structured lipids did not inhibit cell proliferation in preneoplastic lesions, but both of them induced apoptosis in remodeling preneoplastic lesions. In addition, histone acetylation and p21 restored expression tributyrin molecular mechanisms were related to modulation of p53 nuclear shuttling mechanisms. In the present study, it was observed a substantial increase in p53 nuclear/cytoplasmic ratio and importin-alpha in preneoplastic livers of tributyrin treated rats, but not in those treated with structured lipids. In contrast, treatment structured lipids downregulated expression of major oncogenes Bcl2, Ccnd2, Pdgfa, and Vegfa; and upregulated expression of critical tumor suppressor genes, Cdh13, Socs3 and Fhit. Hence, although structured lipids and tributyrin show similar chemopreventive potential, the results suggest that the new compound does not exhibit HDACi activity, and that its inhibitory effects may be attributed to the modulation of oncogenes and tumor suppressor genes expression.

Plusieurs lymphomes à cellules B présentent des anomalies génétiques qui sont importantes pour déterminer leurs caractéristiques biologiques et peuvent être utiles pour le diagnostic. Les types les plus courants sont le lymphome folliculaire et le lymphome diffus à grandes cellules B (LDGCB), qui représentent à eux deux plus de 60 % de tous les lymphomes. Les LDGCB sont agressifs mais peuvent être traités par chimiothérapie à agents multiples. Cependant, les gènes suppresseurs de tumeur (GST) potentiellement responsables de la lymphomagenèse ne sont pas tous connus. Le rationnel de ce projet reposait sur des données non publiées du projet translationnel GHEDI (déchiffrer l'hétérogénéité génétique du lymphome diffus à grandes cellules B à l'ère du rituximab). Une hybridation génomique comparative (CGH) (puce Agilent 180 K) a été réalisée sur une série de 202 LDGCB de la série GHEDI et 40 % des délétions de la région 6q21 ont été identifiées, dont la région minimale commune délétée qui contient le gène HACE1. Par ailleurs, l'analyse transcriptomique a montré une corrélation significative entre le nombre de copies du gène et le niveau d'expression. Le gène HACE1, situé sur le chromosome 6q, code pour une ubiquitine ligase E3 et est régulé négativement chez l'homme dans les tumeurs, y compris les neuroblastomes et les lymphomes à cellules tueuses naturelles (NK). Il a été montré que le gène HACE1 ubiquityle Rac1, une protéine impliquée dans la prolifération cellulaire et la progression G2/M du cycle cellulaire. La fonction du gène HACE1 et les facteurs impliqués dans sa régulation transcriptionnelle sont en grande partie inconnus dans le contexte des lymphomes à cellules B. Dans cette étude, nous avons examiné si le gène HACE1 était un gène candidat dans la région génomique 6q impliqué dans la lymphomagenèse des LDGCB et plus largement dans les lymphomes B. Nous avons déterminé la fréquence de l'inactivation du gène HACE1 dans le lymphome à cellules B et analysé les mécanismes impliqués dans son extinction. / Several B-cell lymphomas have characteristic genetic abnormalities that are important in determining their biologic features and can be useful in differential diagnosis. Historically, classical Hodgkin lymphomas have been distinguished from non-Hodgkin lymphomas (NHL). The most common types are follicular lymphoma and diffuse large B-cell lymphoma (DLBCL), which together make up more than 60% of all lymphomas. DBCL are aggressive but potentially curable with multi-agent chemotherapy. However the putative tumor suppressor genes (TSG) responsible for lymphomagenesis still remain unknown. The rational of this project was based on unpublished data from the translational project GHEDI (Deciphering the Genetic Heterogeneity of Diffuse large B-cell lymphoma in the rituximab era). Array comparative genomic hybridization (aCGH) (Agilent 180 K) was performed in a series of 202 DLBCL and found 40% of deletions of 6q21 region, whose minimal commune deleted region (MCR) contains HACE1 gene. Furthermore, transcriptomic analysis showed a significant correlation between gene copy number and expression level. HACE1, located on chromosome 6q, encodes an E3 ubiquitin ligase and is downregulated in human tumors such as neuroblastomas and natural killer (NK) lymphomas. HACE1 has been shown to ubiquitylate Rac1, a protein involved in cell proliferation and G2/M cell cycle progression. The function of HACE1 and the factors involved in its transcriptional regulation are largely unknown in the context of B-cell lymphomas. In this study, we investigated whether HACE1 is a candidate gene in the 6q genomic region involved in DLBCL lymphomagenesis. We determined the frequency of HACE1 inactivation in B-cell lymphoma and analyzed the mechanisms involved in its silencing. We show, by RT-qPCR, that HACE1 gene is constitutively expressed in normal lymph nodes and in normal B-cells isolated from peripheral blood, contrasting with a strong downregulation of its expression in more than 70% (77/111) of B-cell lymphoma cases and in four tested B-Lymphoma cell lines. HACE1 gene copy number was assessed by quantitative multiplex PCR of short fluorescent fragments (QMPSF) and array for comparative genomic hybridization (aCGH) in 91 DLBCL cases.

A combinação de agentes quimiopreventivos com diferentes mecanismos de ação tem sido considerada uma estratégia promissora para a prevenção do câncer. Dentre os diversos compostos bioativos em alimentos, destacam-se a tributirina, um pró-fármaco do ácido butírico presente em laticínios e produzido pela fermentação de fibras dietéticas, e o óleo de linhaça, fonte de ácido alfa linolênico. Nesse contexto, foi avaliada a atividade quimiopreventiva de lipídios estruturados obtidos a partir da interesterificação enzimática de tributirina e óleo de linhaça durante a fase de promoção inicial da hepatocarcinogênese experimental. Ratos Wistar machos submetidos ao modelo do hepatócito resistente receberam diariamente, por via intragástrica (i.g), maltodextrina, óleo de linhaça, tributirina, a mistura não esterificada ou lipídios estruturados durante a fase de promoção inicial. O tratamento com lipídios estruturados demonstrou atividade quimiopreventiva comparável à da tributirina, mesmo resultando em menor concentração hepática de ácido butírico. Tanto a tributirina quanto os lipídios estruturados não inibiram a proliferação celular em lesões preneoplásicas, mas induziram a apoptose naquelas em remodelação. Os efeitos inibitórios da tributirina em fases iniciais da hepatocarcinogênese experimental estão relacionados ao aumento da acetilação de histonas e à modulação de processos de translocação nuclear da p53. No presente estudo, foi observado aumento substancial da razão nuclear/citoplasmática de p53 e importina-alfa em fígados de animais submetidos ao modelo e tratados com tributirina, mas não nos tratados com lipídios estruturados. Por outro lado, o tratamento com lipídios estruturados reduziu a expressão dos oncogenes Bcl2, Ccnd2, Pdgfa, Vegfa e aumentou a expressão dos genes supressores de tumor Cdh13, Fhit e Socs3. Assim, embora o potencial quimiopreventivo dos lipídios estruturados seja comparável ao da tributirina, os resultados sugerem que o novo composto não exibe atividade de HDACi, e que seus efeitos inibitórios na hepatocarcinogênese possam ser atribuídos à modulação da expressão de oncogenes e genes supressores de tumor. / Combination of chemopreventive agents with different mechanisms of action has been considered a promising strategy to cancer prevention. Among several bioactive food compounds, tributyrin, a butyric acid prodrug obtained from dairy products and dietetic fiber fermentation, and flax seed oil, a rich source of alpha linolenic acid have shown chemopreventive potential. Here, we evaluated the chemopreventive activity of structured lipids obtained by enzymatic interesterification of tributyrin and flax seed oil during the early promotion phase of experimental hepatocarcinogenesis. Male Wistar rats subjected to the resistant hepatocyte model were treated daily, i.g, with maltodextrin, flax seed oil, tributyrin, non-sterified blend, or structured lipids. Treatment structured lipids showed similar chemopreventive activity compared to tributyrin, even when structured lipids yielded lower concentrations of butyric in the liver. Tributyrin and structured lipids did not inhibit cell proliferation in preneoplastic lesions, but both of them induced apoptosis in remodeling preneoplastic lesions. In addition, histone acetylation and p21 restored expression tributyrin molecular mechanisms were related to modulation of p53 nuclear shuttling mechanisms. In the present study, it was observed a substantial increase in p53 nuclear/cytoplasmic ratio and importin-alpha in preneoplastic livers of tributyrin treated rats, but not in those treated with structured lipids. In contrast, treatment structured lipids downregulated expression of major oncogenes Bcl2, Ccnd2, Pdgfa, and Vegfa; and upregulated expression of critical tumor suppressor genes, Cdh13, Socs3 and Fhit. Hence, although structured lipids and tributyrin show similar chemopreventive potential, the results suggest that the new compound does not exhibit HDACi activity, and that its inhibitory effects may be attributed to the modulation of oncogenes and tumor suppressor genes expression.