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Acute myeloid leukemia (AML) is a highly lethal malignancy characterized by unchecked expansion of immature myeloid blasts. While certain genetic and cytogenetic aberrations have been associated with chemotherapy response and disease risk, clinical outcomes remain heterogeneous. AML harbors relatively few somatic mutations compared to other cancers, however, it shows marked enrichment for epigenetic regulator alterations, and has been shown to harbor DNA methylation defects. My focus has been to dissect these epigenetic defects using high-throughput DNA methylation data. I first characterized two genome-wide hypermethylation signatures in AML: AML-CpG island methylator phenotype (A-CIMP+), and IDH-associated CIMP (I-CIMP+). While I-CIMP+ leukemias showed significant enrichments for mutations in IDH1 or IDH2, A-CIMP+ cases were mutation independent, and were best defined by their epigenetic defects, and associated transcriptomic changes. Importantly, A-CIMP+ leukemias had relatively favorable clinical outcomes, while I-CIMP+ patients did not. I next sought to characterize epigenetic defects involving demethylation of normally methylated genomic regions. I identified two distinct demethylator phenotypes (DMPs): DMP.1+ and DMP.2+. DMP.1+ AML was largely defined by mutations in DNMT3A, FLT3, and NPM1, while DMP.2+ leukemias harbored favorable-risk genomic rearrangements and a distinct gene expression profile. Both DMPs also carried prognostic information in AML; DMP.1+ cases had poor outcomes, while DMP.2+ patients tended to have favorable survival. Using both CIMP and DMP signatures, I then built an integrated epigenetic model for AML prognosis I termed MethylScore. The MethylScore algorithm was prognostic independent of age and cytogenetic risk in multivariate Cox regression models, suggesting that DNA methylation defects may augment existing clinical tools for risk stratification, and/or treatment selection. Finally, I explored whether DNA methylation signatures and genetic mutations could serve as biomarkers of response to epigenetic therapy, and found that DNA hypermethylation correlated with poor overall survival, and a gene mutation profile was associated with lack of complete remission after treatment with a DNA methylation inhibitor. These data provide evidence of distinct epigenetic signatures in AML that define transcriptionally, genetically, and clinically distinct populations that should be evaluated in future translational/clinical studies. / Biomedical Sciences

Genomic DNA methylation is an epigenetic marker that reflects influences of the environment, aging, and diseases. Although causal mechanisms of these alterations are understudied, the first step to addressing changes in DNA methylation is to map alterations appearing in a particular context. For example, human populations have diverse situational exposures. As an extreme example, the isolated populations of nomadic hunter/gatherer individuals in the Kalahari Desert lack access to most of the conveniences of modern lifestyles. Due to climate and behavioral adaptations of the lifestyle of these isolated populations (acoustic sensitivity to predators, irregular water and food availability), I predicted and demonstrated altered methylation landscapes compared with a non-Khoesan group of southern Africans with more industrialized lifestyles. The sites of differential methylation were assessed for potential functional impact at several example loci. A related project addressed nucleotide variants at interrogated methylation loci. For instance, C to T polymorphisms occurring in some individuals cannot initially be discriminated from loci that have differential cytosine methylation (following bisulfite treatment) in an array-based assay. My solution to this problem was the development of a computational approach to detect loci in methylation array data, which show tiered patterns created by SNP alleles rather than the usual continuum of differential methylation values. This approach was applied to the Kalahari populations and HapMap groups to show the utility of the approach. In the Kalahari populations, post-infancy ages are not recorded. We used functions that utilize DNA methylation to calculate estimates of aging and compared these results with predictions reported by the sample collectors, which were based primarily on interactions with non-nomadic neighbors. I compared the same aging estimates to known ages in the non-Khoesan samples and found correspondence. Although DNA methylation is a good predictor of cellular age, another method is telomere length measurement. To assess a relationship between predictors, I assessed associations in 300 samples between age, DNA methylation, and telomere length. Initial results indicated multiple correlated loci when accounting for gender and ethnicity using a linear model approach. / 2020-07-31T00:00:00Z

Appetite regulation is primarily mediated by the hypothalamus, within which many neurotransmitters that regulate feeding are shared by the stress response circuitry. Stressors, especially those occur during critical periods of life, influence epigenetic programming and gene expression in the long-term. Therefore, the aim of this dissertation was to elucidate how hypothalamic mechanisms of appetite regulation correlate with the stress response and epigenetic modifications, using avian models and intracerebroventricular administration of various appetite-regulating factors. We first administered two methylation modifiers, S-adenosylmethionine (SAM), a methyl donor, and 5-azacytidine (AZA), a methylation inhibitor, to determine their effects on appetite. When measuring food intake immediately post-injection, SAM didn't affect fed or fasted chickens from a line selected for low bodyweight (LWS, individuals with anorexia), but suppressed feeding in fed and fasted broilers. In Japanese quail, SAM transiently induced satiety in fed but not fasted chicks. Intriguingly, AZA increased feeding in fasted LWS but decreased it in fed chicks. While it didn't affect either fed or fasted broilers, AZA induced satiety in both fed and fasted quail. These results suggests that SAM/AZA can directly affect appetite depending on genetics and nutritional state. The LWS chickens, when injected with SAM or AZA on day of hatch, didn't show increased feeding to the orexigenic stimulation of neuropeptide Y central injection on day 5 post-hatch. This suggests that epigenetic modifications occurred following SAM/AZA injection and affect appetite regulation that persisted. In other studies, we injected broilers with prostaglandin E2 (PGE2) or β-melanocyte-stimulating hormone (β-MSH) since their effects on appetite are unknown in meat-type chicks. We found that they both potently induced satiety, but the effective duration was longer in β-MSH-injected birds (up to 9 hours) than in PGE2-injected chicks (lasted for 1.5 hours). They both activated the paraventricular nucleus of the hypothalamus. The satiety induced by β-MSH mainly involved corticotropin-releasing factor and mesotocin, while the effect of PGE2 included ghrelin and brain-derived neurotropic factor. Nevertheless, all affected appetite-related factors have connections with the stress response. Thus, our results demonstrate that the hypothalamic mechanisms underlying anorexia induced by different neuroactive molecules involve the stress response and epigenetic modifications. / Doctor of Philosophy / Eating disorders (EDs) all involve abnormal eating behaviors and altered body weight. These aberrant conditions are associated with a change in metabolism and pose great risk to human health and animal production, and are generally characterized by two opposite outcomes, anorexia and obesity. Although affected by multiple systems within the body, appetite regulation is mainly controlled by the brain, especially the hypothalamus. Thus, it is important to understand the hypothalamic mechanisms underlying the regulation of eating behavior. In the hypothalamus, many neurotransmitters affect multiple pathways, including the stress response and those that regulate appetite. Additionally, stress, especially when occurring during early life, can influence behaviors later in life through inducing epigenetic modifications (changes to the packaging of the DNA nucleotide sequence) that alter gene expression. Therefore, the aim of this dissertation was to elucidate how hypothalamic mechanisms of appetite regulation correlate with the stress response and epigenetic modifications, using avian models. To focus on the effects within the brain, we directly injected various appetite regulating factors into the brain in each of the experiments. Previously, our group demonstrated that early-life cold exposure and delayed food supply changed DNA methylation and affected expression of appetite-related genes and food intake in a chicken line predisposed to anorexia. We herein injected chicks with one of two methylation modifiers, S-adenosylmethionine (SAM), a methyl donor, and 5-azacytidine (AZA), a methylation inhibitor, to evaluate their effects on feeding behavior. When food intake was measured immediately after injection, SAM did not affect food intake in either fed or fasted line chickens from a genetic line selected for low body weight (LWS, individuals with anorexia), but suppressed food intake in both fed and fasted broiler (meat-type chickens) chicks. In Japanese quail, however, SAM only transiently induced satiety in fed chicks but not in fasted ones. Intriguingly, AZA increased food intake in fasted LWS chicks but decreased it in fed chicks, but AZA had no effects on food consumption in either fed or fasted broilers. Additionally, AZA suppressed food intake in both fed and fasted quail. These results suggest that SAM and AZA affect appetite differently depending on genetic background and nutritional states. LWS chickens, when injected with SAM or AZA on day of hatch, did not eat more after being injected with the potent hunger factor, neuropeptide Y, at 5 days of age. This indicates that epigenetic modifications occurred following SAM/AZA injection and had persisting effects on appetite regulation. In the other two studies, we injected broiler chicks with prostaglandin E2 (PGE2), a fatty acid-based molecule, or β-melanocyte-stimulating hormone (β-MSH), a peptide. These two molecules have been reported to regulate feeding behavior in rodents and layer-type chickens, but effects are unknown in broilers. They both potently decreased food intake in broilers, but the effective duration was much longer in β-MSH-injected birds (up to 9 hours) than in PGE2-injected chicks (lasted for 1.5 hours). They both activated the paraventricular nucleus of the hypothalamus, while β-MSH also activated the arcuate nucleus and ventromedial nucleus. We further found that the anorexia induced by β-MSH involved corticotropin-releasing factor, mesotocin, and their receptors, while the effect of PGE2 was associated with a change in ghrelin and brain-derived neurotropic factor gene expression. Nevertheless, all of these affected factors have connections with the stress response. Thus, results indicate that the hypothalamic mechanisms underlying anorexia induced by different neuroactive molecules involve the stress response and epigenetic modifications.

Obesity is a major health condition in which little is known about the molecular mechanisms that drive it. The hypothalamus is the primary control center for controlling both food intake and energy expenditure in order to maintain the body's energy balance and dysregulation of molecular processes in this region have been implicated in the development and progression of obesity. Recently, several studies have shown altered DNA methylation of critical appetite genes, including the satiety gene Pomc, in the hypothalamus of rodents fed a high fat obesogenic diet. However, it has not previously been studied whether diet-induced changes in DNA methylation of critical appetite genes in the hypothalamus contributes to the development and persistence of the obesity phenotype. Further, DNA 5-hydroxymethylation (5-hmC) is one type of DNA methylation that is 10 times more abundant in the brain than peripheral tissues. However, to date, no study has been conducted examining whether DNA 5-hmC becomes altered in the brain following weight gain and/or contributes to the obesity phenotype. Additionally, there is also evidence to support that exposure to a high fat diet dysregulates the activity of the ubiquitin-proteasome system, the master regulator of protein degradation in cells, in the hypothalamus of male rodents. Despite this, whether this can occur in both sexes and directly contributes to abnormal weight gain has not been investigated. Here, we used a rodent diet-induced obesity model in combination with quantitative molecular assays and CRISPR-dCas9 manipulations to test the role of hypothalamic 1) DNA 5-hmC levels, 2) Pomc methylation, and 3) dysregulated ubiquitin-proteasome signaling in abnormal weight gain following exposure to obesogenic diets. We found that males, but not females, have decreased levels of DNA 5-hmC in the hypothalamus following exposure to a high fat diet, which tracked body weight. Short-term exposure to a high fat diet, which does not result in significant weight gain, resulted in decreased hypothalamic DNA 5-hmC levels, suggesting these changes occur prior to obesity development. Moreover, decreases in DNA 5-hmC persist even after the high fat diet is removed. Importantly, CRISPR-dCas9 mediated upregulation of DNA 5-hmC enzymes in the male, but not female, hypothalamus significantly reduced the percentage of weight gained on the high fat diet relative to controls. Next, we used the CRISPR-dCas9-TET1 and dCas9-DNMT3a systems to test the role of Pomc DNA methylation in the hypothalamus in abnormal weight gain following acute exposure to a high fat diet in male rats. We found that exposure to a high fat diet increases Pomc DNA methylation and reduces gene expression in the hypothalamus. Despite this, we found that CRISPR-dCas9-TET1-mediated demethylation of Pomc was not sufficient to prevent abnormal weight gain following exposure to a high fat diet. Moreover, CRISPR-dCas9-DNMT3a-mediated methylation of Pomc did not alter weight gain following exposure to standard or high fat diets. Finally, we found that both males and females showed dynamic downregulation of proteasome activity, decreases in proteasome subunit expression and an accumulation of degradation-specific K48 polyubiquitinated proteins in the hypothalamus. However, while the CRISPR-dCas9 system was able to selectively increase some forms of proteasome activity, it was unable to prevent diet-induced proteasome downregulation or abnormal weight gain. Collectively, this data reveals novel, sex-specific differences in the engagement of the ubiquitin proteasome system and role of DNA 5-hydroxymethylation in the hypothalamus during the development of the obesity phenotype. / Doctor of Philosophy / Obesity affects 34% of the American population at an annual cost of more than $340 billion in healthcare and is a risk factor for the development of diabetes and certain cancers. Genetic and environmental factors have also been shown to influence the expression of genes that play a role in the development of obesity. The hypothalamus coordinates many integral activities such as hormone regulation and feed intake and numerous studies have observed altered hypothalamic gene regulation in obesity models. Recently, several studies have shown altered DNA methylation of critical appetite genes, including the satiety gene Pomc, in the hypothalamus of rodents fed a high fat obesogenic diet. However, it has not previously been studied whether diet-induced changes in DNA methylation of critical appetite genes in the hypothalamus contributes to the development and persistence of the obesity phenotype. Further, DNA 5-hydroxymethylation (5-hmC) is one type of DNA methylation that is 10 times more abundant in the brain than peripheral tissues. However, to date, no study has been conducted examining whether DNA 5-hmC becomes altered in the brain following weight gain and/or contributes to the obesity phenotype. Additionally, there is also evidence to support that exposure to a high fat diet dysregulates the activity of the ubiquitin-proteasome system, the master regulator of protein degradation in cells, in the hypothalamus of male rodents. Despite this, whether this can occur in both sexes and directly contributes to abnormal weight gain has not been investigated. In this document, I outline a series of experiments designed to elucidate novel, sex-specific differences in the role of the ubiquitin proteasome system and DNA 5-hydroxymethylation in the hypothalamus during the development of the obesity phenotype.

A Doença de Parkinson é a segunda doença neurodegenerativa mais comum na atualidade. Cerca de 10% dos casos da doença estão relacionados com fatores genéticos e os outros 90% são devido a fatores ambientais e epigenéticos. Evidências indicam alterações na metilação de genes relacionados ao desenvolvimento da doença de Parkinson. No entanto, não se sabe o efeito de inibidores da metilação de DNA sobre a neurotoxicidade induzida por MPP+, uma neurotoxina que mimetiza processos neurodegenerativos associados ao Parkinson in vitro. Portanto, este trabalho teve como objetivo avaliar o efeito dos inibidores da metilação de DNA (RG108, n-ftaloil-l-triptofano e 5azadC, 5-aza-2´-deoxycytidina) e do doador universal de grupamentos metil (SAM, S-adenosilmetionina) sobre neurotoxicidade induzida por MPP+ em cultura de células imortalizadas (PC12), por meio da análise da viabilidade celular avaliada no teste do MTT (3 - [4,5 dimetiltiazol-2-il] -2,5-difenil-tetrazólio); e da análise de neuritogênese, na presença e na ausência de MPP+. Os resultados demonstraram que: 1. o tratamento com DNMTi (inibidor da DNA metiltransferase) ou com SAM induziram efeito per se sobre a viabilidade celular, apenas quando incubados em altas concentrações e em perídos prolongados (24h); 2. não modificaram a morte celular induzida pelo MPP+, em baixas concentrações, mas agravaram a neurotoxicidade quando incubados em altas concentrações ou por períodos prolongados (24h); 3. essas drogas induziram neuritogênese per se e potencializaram a neuritogênese induzida pelo NGF (fator de crescimento neural); 4. protegeram parcialmente contra a diminuição da neuritogênse induzida pelo MPP+. O conjunto de dados sugere que tanto os DNMTi quanto o SAM podem ser citotóxicos, dependen de suas concentrações e do tempo de exposição à droga. No entanto, essas drogas são capazes de aumentar a neuritogênese (diferenciação celular) e proteger contra a neurotoxicidade celular induzida pelo NGF, em células diferenciadas. / Parkinson\'s disease is the second most common neurodegenerative disease nowadays. About 10% of the disease cases are related to genetic factors and the other 90% are due to environmental and epigenetic factors. Evidence indicates changes in DNA methylation in genes related to the development of Parkinson\'s disease. However, the effect of DNA methylation inhibitors on MPP+-induced neurotoxicity, a drug that mimics neurodegenerative processes associated with Parkinson\'s in vitro, is not known. The aim of this study was to evaluate the effect of DNA methylation inhibitors (RG108, N-phthalyl-L-tryptophan and 5azadC, 5-aza-2?-deoxycytidine) and of the universal donor of methyl group (SAM, S-adenosyl methionine) on: 1. MPP+ -induced neurotoxicity in culture of immortalized cells (PC12), by analysis of cell viability in the MTT (3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyltetrazolium) test; 2. neuritogenesis, in the presence and absence of MPP +. Results indicated that: 1. treatment with DNMTi or SAM induced effects per se on cell viability only at higher concentrations and after prolonged periods of incubation (24h); 2. DNMTi (DNA methyltransferase inhibitors) and SAM increased cell differentiation and neuritogenesis per se, especially when incubated for 30 minutes, as well as they potentiated NGF-induced neurogenesis; 3. the drugs attenuated MPP+-induced effects on neuritogenesis. Altogether, these data suggests short treatment with both DNMTi and SAM do not cause cellular cytotoxicity (cell death), but are able to increase neuritogenesis (cell differentiation) and protect against MPP+-induced neurotoxicity in differentiated cells.

Wang, Shiyan. / Thesis (Ph.D.)--Chinese University of Hong Kong, 2011. / Includes bibliographical references (leaves 123-139). / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Abstract also in Chinese.

Cheung Kin Fai. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2006. / Includes bibliographical references (leaves 87-105). / Abstracts in English and Chinese. / Abstract (English version) --- p.i / Abstract (Chinese version) --- p.iii / Acknowledgments --- p.vi / Table of Contents --- p.v / List of Tables --- p.viii / List of Figures --- p.iv / List of Abbreviations --- p.xi / Chapter CHAPTER 1 --- GENERAL INTRODUCTION --- p.1 / Chapter CHAPTER 2 --- LITERATURE REVIEW --- p.3 / Chapter 2.1 --- Multiple myeloma --- p.3 / Chapter 2.2 --- Epidemiology of MM --- p.3 / Chapter 2.3 --- Risk factors --- p.4 / Chapter 2.4 --- Pathophysiology of MM --- p.5 / Chapter 2.5 --- Clinical presentations and diagnosis --- p.6 / Chapter 2.5.1 --- Diagnosis --- p.6 / Chapter 2.5.1.1 --- Laboratory testing of blood and urine --- p.6 / Chapter 2.5.1.2 --- Radiographic evaluations --- p.1 / Chapter 2.5.1.3 --- Bone marrow biopsy --- p.7 / Chapter 2.6 --- Staging and classification --- p.9 / Chapter 2.6.1 --- Staging --- p.9 / Chapter 2.6.2 --- Classification --- p.11 / Chapter 2.6.2.1 --- Monoclonal gammopathy of undetermined significance --- p.11 / Chapter 2.6.2.2 --- Asymptomatic MM --- p.12 / Chapter 2.6.2.3 --- Smouldering MM --- p.12 / Chapter 2.6.2.4 --- Indolent MM --- p.12 / Chapter 2.6.2.5 --- Symptomatic MM --- p.12 / Chapter 2.7 --- Treatment --- p.14 / Chapter 2.8 --- Epigenetics: DNA methylation --- p.15 / Chapter 2.9 --- Fundamental aspects of DNA methylation --- p.16 / Chapter 2.9.1 --- CpG islands --- p.16 / Chapter 2.9.2 --- Roles of DNA methylation --- p.16 / Chapter 2.9.3 --- Proposed mechanisms of transcriptional repression mediated by methylation --- p.18 / Chapter 2.10 --- Possible mechanisms to initiate aberrant DNA methylation --- p.21 / Chapter 2.11 --- DNA methylation in tumorigenesis --- p.22 / Chapter 2.11.1 --- Oncogenic point C → T mutation --- p.22 / Chapter 2.11.2 --- Global DNA hypomethylation --- p.23 / Chapter 2.11.3 --- Regional DNA hypermethylation --- p.23 / Chapter 2.12 --- Aberrant DNA methylation in MM --- p.25 / Chapter 2.12.1 --- Self-sufficiency in growth signals --- p.25 / Chapter 2.12.2 --- Evading apoptosis --- p.26 / Chapter 2.12.3 --- Insensitivity to antigrowth signals --- p.26 / Chapter 2.12.4 --- Tissue invasion and metastasis --- p.27 / Chapter 2.12.5 --- Infinite replicative potential --- p.28 / Chapter 2.12.6 --- Genome instability --- p.30 / Chapter 2.13 --- Methodologies of DNA methylation analysis --- p.32 / Chapter 2.13.1 --- Genome wide screening method: MS.AP-PCR --- p.32 / Chapter 2.13.2 --- Combined bisulfite restriction analysis --- p.34 / Chapter 2.13.3 --- Cloned bisulfite genomic sequencing --- p.36 / Chapter 2.13.4 --- Treatment with demethylating agent --- p.36 / Chapter CHAPTER 3 --- MATERIALS AND METHODS --- p.38 / Chapter 3.1 --- MM specimens --- p.38 / Chapter 3.1.1 --- MM samples --- p.38 / Chapter 3.1.2 --- MM cell lines --- p.38 / Chapter 3.2 --- Magnetic cell sorting of CD138-positive plasma cells --- p.39 / Chapter 3.3 --- Isolation of nuclear pellet from PB --- p.41 / Chapter 3.4 --- "DNA extraction from MM cell lines, MM plasma cells and PB" --- p.41 / Chapter 3.5 --- MS.AP-PCR --- p.42 / Chapter 3.5.1 --- Restriction enzyme digestion of genomic DNA --- p.42 / Chapter 3.5.2 --- Arbitrarily primed polymerase chain reaction --- p.42 / Chapter 3.5.3 --- Isolation of differentially methylated DNA fragments --- p.43 / Chapter 3.6 --- Cloning of differentially methylated DNA fragments --- p.46 / Chapter 3.6.1 --- TA cloning --- p.46 / Chapter 3.6.2 --- Heat shock transformation --- p.46 / Chapter 3.6.3 --- Screening of positive clones by PCR --- p.46 / Chapter 3.6.4 --- Alkaline lysis for plasmid DNA preparation --- p.47 / Chapter 3.7 --- MS.AP-PCR sequence analysis --- p.47 / Chapter 3.7.1 --- Nucleotide sequencing --- p.47 / Chapter 3.7.2 --- CpG islands analysis of differentially methylated sequences --- p.48 / Chapter 3.8 --- DNA methylation analysis --- p.48 / Chapter 3.8.1 --- Sodium bisulfite modification --- p.48 / Chapter 3.8.2 --- Combined bisulfite restriction analysis --- p.49 / Chapter 3.8.3 --- Cloned bisulfite genomic sequencing --- p.49 / Chapter 3.9 --- Gene expression analysis --- p.50 / Chapter 3.9.1 --- RNA extraction --- p.50 / Chapter 3.9.2 --- Reverse transcription PCR --- p.50 / Chapter 3.9.3 --- 5'-aza-2'-deoxycytidine treatment --- p.51 / Chapter CHAPTER 4 --- RESULTS --- p.53 / Chapter 4.1 --- Generation of DNA methylation patterns by MS.AP-PCR --- p.53 / Chapter 4.1.1. --- Global methylation content in MM samples and normal PB lymphocytes --- p.56 / Chapter 4.1.2. --- Differential methylation in MM --- p.56 / Chapter 4.2 --- UCSC BLAT analysis of differentially methylated DNA fragments --- p.60 / Chapter 4.3 --- Identification of two candidate genes with downregulated expression --- p.60 / Chapter 4.4 --- Zinc fingers and homeoboxes 2 (ZHX2) --- p.62 / Chapter 4.4.1 --- ZHX2 CpG islands BLAT search analysis --- p.62 / Chapter 4.4.2 --- Hypermethylation of ZHX2 in MM cell lines --- p.63 / Chapter 4.4.3 --- Downregulated expression of ZHX2 in methylated MM cell lines --- p.66 / Chapter 4.4.4 --- Restoration of ZHX2 expression by 5-Aza-dC treatment --- p.67 / Chapter 4.4.5 --- Unmethylation of ZHX2 in primary MM tumors --- p.68 / Chapter 4.5 --- Ring finger protein 180 (RNF180) --- p.69 / Chapter 4.5.1 --- RNF180 CpG islands BLAT search analysis --- p.69 / Chapter 4.5.2 --- Hypermethylation of RNF180 in MM cell lines --- p.70 / Chapter 4.5.3 --- Downregulated expression of RNF180 in methylated MM cell lines --- p.73 / Chapter 4.5.4 --- Restoration of RNF180 expression by 5-Aza-dC treatment --- p.74 / Chapter 4.5.5 --- Methylation of RNF180 in primary MM tumors --- p.75 / Chapter CHAPTER 5 --- DISCUSSION --- p.76 / Chapter 5.1 --- Importance of methylation in MM --- p.76 / Chapter 5.2 --- Genome-wide screening approach by MS.AP-PCR --- p.76 / Chapter 5.3 --- Sample selection in MS.AP-PCR --- p.78 / Chapter 5.4 --- Methylation patterns in MM --- p.79 / Chapter 5.5 --- Candidate genes selection strategies --- p.81 / Chapter 5.6 --- Zinc fingers and homeoboxes 2 --- p.81 / Chapter 5.7 --- Ring finger protein 180 --- p.83 / Chapter 5.8 --- Limitations --- p.84 / Chapter CHAPTER 6 --- CONCLUSION --- p.86 / REFERENCES --- p.87