1 1744 212 EARLY LIFE ADVERSE ENVIRONMENTAL EXPOSURES INCREASE THE RISK OF UTERINE FIBROID DEVELOPMENT: ROLE OF EPIGENETIC REGULATION. UTERINE FIBROIDS [UF(S), AKA: LEIOMYOMA] ARE THE MOST IMPORTANT BENIGN NEOPLASTIC THREAT TO WOMEN'S HEALTH. THEY ARE THE MOST COMMON CAUSE OF HYSTERECTOMY IMPOSING UNTOLD PERSONAL CONSEQUENCES AND 100S OF BILLIONS OF HEALTHCARE DOLLARS, WORLDWIDE. CURRENTLY, THERE IS NO LONG TERM EFFECTIVE FDA-APPROVED MEDICAL TREATMENT AVAILABLE, AND SURGERY IS THE MAINSTAY. THE ETIOLOGY OF UFS IS NOT FULLY UNDERSTOOD. IN THIS REGARD, WE AND OTHERS HAVE RECENTLY REPORTED THAT SOMATIC MUTATIONS IN THE GENE ENCODING THE TRANSCRIPTIONAL MEDIATOR SUBUNIT MED12 ARE FOUND TO OCCUR AT A HIGH FREQUENCY ( APPROXIMATELY 85%) IN UFS. UFS LIKELY ORIGINATE WHEN A MED12 MUTATION OCCURS IN A MYOMETRIAL STEM CELL CONVERTING IT INTO A TUMOR-FORMING STEM CELL LEADING TO A CLONAL FIBROID LESION. ALTHOUGH THE MOLECULAR ATTRIBUTES UNDERLYING THE MECHANISTIC FORMATION OF UFS IS LARGELY UNKNOWN, A GROWING BODY OF LITERATURE IMPLICATES UNFAVORABLE EARLY LIFE ENVIRONMENTAL EXPOSURES AS POTENTIALLY IMPORTANT CONTRIBUTORS. EARLY LIFE EXPOSURE TO EDCS DURING SENSITIVE WINDOWS OF DEVELOPMENT CAN REPROGRAM NORMAL PHYSIOLOGICAL RESPONSES AND ALTER DISEASE SUSCEPTIBILITY LATER IN LIFE. NEONATAL EXPOSURE TO THE EDCS SUCH AS DIETHYLSTILBESTROL (DES) AND GENISTEIN DURING REPRODUCTIVE TRACT DEVELOPMENT HAS BEEN SHOWN TO INCREASE THE INCIDENCE, MULTIPLICITY AND OVERALL SIZE OF UFS IN THE EKER RAT MODEL, CONCOMITANTLY REPROGRAMMING ESTROGEN-RESPONSIVE GENE EXPRESSION. IMPORTANTLY, EDC EXPOSURE REPRESSES ENHANCER OF ZESTE 2 (EZH2) AND REDUCES LEVELS OF HISTONE 3 LYSINE 27 TRIMETHYLATION (H3K27ME3) REPRESSIVE MARK THROUGH ESTROGEN RECEPTOR/PHOSPHATIDYLINOSITIDE 3-KINASES/PROTEIN KINASE B NON-GENOMIC SIGNALING IN THE DEVELOPING UTERUS. CONSIDERING THE FACT THAT DISTINCT MEDIATOR COMPLEX SUBUNIT 12 (MED12) MUTATIONS ARE DETECTED IN DIFFERENT FIBROID LESIONS IN THE SAME UTERUS, THE EMERGENCE OF EACH MED12 MUTATION IS LIKELY AN INDEPENDENT EVENT IN AN ALTERED MYOMETRIAL STEM CELL. IT IS THEREFORE POSSIBLE THAT A CHRONIC REDUCTION IN DNA REPAIR CAPACITY EVENTUALLY CAUSES THE EMERGENCE OF MUTATIONS SUCH AS MED12 IN MYOMETRIAL STEM CELLS CONVERTING THEM INTO FIBROID TUMOR-FORMING STEM CELLS, AND THEREBY LEADS TO THE DEVELOPMENT OF UFS. ADVANCING OUR UNDERSTANDING OF THE MECHANISTIC ROLE EPIGENETIC REGULATION OF STEM CELLS PLAYS IN MEDIATING RISK AND TUMORIGENESIS WILL HELP IN POINTING THE WAY TOWARD THE DEVELOPMENT OF NOVEL THERAPEUTIC OPTIONS. 2016 2 3174 50 H19 LNCRNA IDENTIFIED AS A MASTER REGULATOR OF GENES THAT DRIVE UTERINE LEIOMYOMAS. UTERINE LEIOMYOMAS OR FIBROIDS (UFS) ARE BENIGN TUMORS CHARACTERIZED BY HYPERPLASTIC SMOOTH MUSCLE CELLS AND EXCESSIVE DEPOSITION OF EXTRACELLULAR MATRIX (ECM). AFFLICTING ~80% OF WOMEN, AND SYMPTOMATIC IN 25%, UFS BRING TREMENDOUS SUFFERING AND ARE AN ECONOMIC BURDEN WORLDWIDE; THEY CAUSE SEVERE PAIN AND BLEEDING, AND ARE THE LEADING CAUSE OF HYSTERECTOMY. YET, UFS ARE SEVERELY UNDERSTUDIED WITH FEW EFFECTIVE TREATMENT OPTIONS AVAILABLE; THOSE THAT ARE AVAILABLE FREQUENTLY HAVE SIGNIFICANT SIDE EFFECTS SUCH AS MENOPAUSAL SYMPTOMS. RECENTLY, INTEGRATED GENOME-SCALE STUDIES HAVE REVEALED MUTATIONS AND FIBROID SUBTYPE-SPECIFIC EXPRESSION CHANGES IN KEY DRIVER GENES, WITH MED12 AND HMGA2 TOGETHER CONTRIBUTING TO NEARLY 90% OF ALL UFS, BUT THEIR REGULATION OF EXPRESSION IS POORLY CHARACTERIZED. HERE WE REPORT THAT THE EXPRESSION OF H19 LONG NONCODING RNA (LNCRNA) IS ABERRANTLY INCREASED IN UFS. USING CELL CULTURE AND GENOME-WIDE TRANSCRIPTOME AND METHYLATION PROFILING ANALYSES, WE DEMONSTRATE THAT H19 PROMOTES EXPRESSION OF MED12, HMGA2, AND KEY ECM-REMODELING GENES VIA MULTIPLE MECHANISMS INCLUDING A NEW CLASS OF EPIGENETIC MODIFICATION BY TET3. OUR RESULTS MARK THE FIRST EXAMPLE OF AN EVOLUTIONARILY CONSERVED LNCRNA IN PATHOGENESIS OF UFS AND REGULATION OF TET EXPRESSION. GIVEN THE LINK BETWEEN A H19 SINGLE-NUCLEOTIDE POLYMORPHISM (SNP) AND INCREASED RISK AND TUMOR SIZE OF UFS, AND THE EXISTENCE OF MULTIPLE FIBROID SUBTYPES DRIVEN BY KEY PATHWAY GENES REGULATED BY H19, WE PROPOSE A UNIFYING MECHANISM FOR PATHOGENESIS OF UTERINE FIBROIDS MEDIATED BY H19 AND IDENTIFY A PATHWAY FOR FUTURE EXPLORATION OF NOVEL TARGET THERAPIES FOR UTERINE LEIOMYOMAS. 2019 3 2295 35 EPIGENETIC REGULATION IN UTERINE FIBROIDS-THE ROLE OF TEN-ELEVEN TRANSLOCATION ENZYMES AND THEIR POTENTIAL THERAPEUTIC APPLICATION. UTERINE FIBROIDS (UFS) ARE MONOCLONAL, BENIGN TUMORS THAT CONTAIN ABNORMAL SMOOTH MUSCLE CELLS AND THE ACCUMULATION OF EXTRACELLULAR MATRIX (ECM). ALTHOUGH BENIGN, UFS ARE A MAJOR SOURCE OF GYNECOLOGIC AND REPRODUCTIVE DYSFUNCTION, RANGING FROM MENORRHAGIA AND PELVIC PAIN TO INFERTILITY, RECURRENT MISCARRIAGE, AND PRETERM LABOR. MANY RISK FACTORS ARE INVOLVED IN THE PATHOGENESIS OF UFS VIA GENETIC AND EPIGENETIC MECHANISMS. THE LATTER INVOLVING DNA METHYLATION AND DEMETHYLATION REACTIONS PROVIDE SPECIFIC DNA METHYLATION PATTERNS THAT REGULATE GENE EXPRESSION. ACTIVE DNA DEMETHYLATION REACTIONS MEDIATED BY TEN-ELEVEN TRANSLOCATION PROTEINS (TETS) AND ELEVATED LEVELS OF 5-HYDROXYMETHYLCYTOSINE HAVE BEEN SUGGESTED TO BE INVOLVED IN UF FORMATION. THIS REVIEW PAPER SUMMARIZES THE MAIN FINDINGS REGARDING THE FUNCTION OF TET ENZYMES AND THEIR ACTIVITY DYSREGULATION THAT MAY TRIGGER THE DEVELOPMENT OF UFS. UNDERSTANDING THE ROLE THAT EPIGENETICS PLAYS IN THE PATHOGENESIS OF UFS MAY POSSIBLY LEAD TO A NEW TYPE OF PHARMACOLOGICAL FERTILITY-SPARING TREATMENT METHOD. 2022 4 828 42 CHARACTERIZATION OF M (6) A MODIFIERS AND RNA MODIFICATIONS IN UTERINE FIBROIDS. UTERINE LEIOMYOMA OR FIBROIDS ARE THE MOST COMMON PREVALENT NONCANCEROUS TUMORS OF THE UTERINE MUSCLE LAYER. COMMON SYMPTOMS ASSOCIATED WITH FIBROIDS INCLUDE PELVIC PAIN, HEAVY MENSTRUAL BLEEDING, ANEMIA, AND PELVIC PRESSURE. THESE TUMORS ARE A LEADING CAUSE OF GYNECOLOGICAL CARE BUT LACK LONG-TERM THERAPY AS THE ORIGIN AND DEVELOPMENT OF FIBROIDS ARE NOT WELL UNDERSTOOD. SEVERAL NEXT-GENERATION SEQUENCING TECHNOLOGIES HAVE BEEN PERFORMED TO IDENTIFY THE UNDERLYING GENETIC AND EPIGENETIC BASIS OF FIBROIDS. HOWEVER, THERE REMAINS A SYSTEMIC GAP IN OUR UNDERSTANDING OF MOLECULAR AND BIOLOGICAL PROCESS THAT DEFINE UTERINE FIBROIDS. RECENT EPITRANSCRIPTOMICS STUDIES HAVE UNRAVELED RNA MODIFICATIONS THAT ARE ASSOCIATED WITH ALL FORMS OF RNA AND ARE THOUGHT TO INFLUENCE BOTH NORMAL PHYSIOLOGICAL FUNCTIONS AND THE PROGRESSION OF DISEASES. WE QUANTIFIED RNA EXPRESSION PROFILES BY ANALYZING PUBLICLY AVAILABLE RNA-SEQ DATA FOR 15 KNOWN EPIGENETIC MEDIATORS TO IDENTIFY THEIR EXPRESSION PROFILE IN UTERINE FIBROIDS COMPARED TO MYOMETRIUM. TO VALIDATE OUR FINDINGS, WE PERFORMED RT-QPCR ON A SEPARATE COHORT OF UTERINE FIBROIDS TARGETING THESE MODIFIERS CONFIRMING OUR RNA-SEQ DATA. WE THEN EXAMINED PROTEIN PROFILES OF KEY M (6) A MODIFIERS IN FIBROIDS AND THEIR MATCHED MYOMETRIUM. IN CONCORDANCE WITH OUR RNA EXPRESSION PROFILES, NO SIGNIFICANT DIFFERENCES WERE OBSERVED IN THESE PROTEINS IN UTERINE FIBROIDS COMPARED TO MYOMETRIUM. TO DETERMINE ABUNDANCE OF RNA MODIFICATIONS, MRNA AND SMALL RNA FROM FIBROIDS AND MATCHED MYOMETRIUM WERE ANALYZED BY UHPLC MS/MS. IN ADDITION TO THE PREVALENT N6-METHYLADENOSINE (M (6) A), WE IDENTIFIED 11 OTHER KNOWN MODIFIERS BUT DID NOT IDENTIFY ANY ABERRANT EXPRESSION IN FIBROIDS. WE THEN MINED A PREVIOUSLY PUBLISHED DATASET AND IDENTIFIED DIFFERENTIAL EXPRESSION OF M (6) A MODIFIERS THAT WERE SPECIFIC TO FIBROID GENETIC SUB-TYPE. OUR ANALYSIS ALSO IDENTIFIED M (6) A CONSENSUS MOTIFS ON GENES PREVIOUSLY IDENTIFIED TO BE DYSREGULATED IN UTERINE FIBROIDS. OVERALL, USING STATE-OF-THE-ART MASS SPECTROMETRY, RNA EXPRESSION AND PROTEIN PROFILES, WE CHARACTERIZED AND IDENTIFIED DIFFERENTIALLY EXPRESSED M (6) A MODIFIERS IN RELATION TO DRIVER MUTATIONS. DESPITE THE USE OF SEVERAL DIFFERENT APPROACHES, WE IDENTIFIED LIMITED DIFFERENTIAL EXPRESSION OF RNA MODIFIERS AND ASSOCIATED MODIFICATIONS IN UTERINE FIBROIDS. HOWEVER, CONSIDERING THE HIGHLY HETEROGENOUS GENOMIC AND CELLULAR NATURE OF FIBROIDS, AND THE POSSIBLE CONTRIBUTION OF SINGLE MOLECULE M (6) A MODIFICATIONS TO FIBROID PATHOLOGY, THERE IS A NEED FOR GREATER IN-DEPTH CHARACTERIZATION OF M (6) A MARKS AND MODIFIERS IN A LARGER AND VARIED PATIENT COHORT. 2023 5 4413 46 MOLECULAR AND CELLULAR INSIGHTS INTO THE DEVELOPMENT OF UTERINE FIBROIDS. UTERINE LEIOMYOMAS REPRESENT THE MOST COMMON BENIGN GYNECOLOGIC TUMOR. THESE HORMONE-DEPENDENT SMOOTH-MUSCLE FORMATIONS OCCUR WITH AN ESTIMATED PREVALENCE OF ~70% AMONG WOMEN OF REPRODUCTIVE AGE AND CAUSE SYMPTOMS INCLUDING PAIN, ABNORMAL UTERINE BLEEDING, INFERTILITY, AND RECURRENT ABORTION. DESPITE THE PREVALENCE AND PUBLIC HEALTH IMPACT OF UTERINE LEIOMYOMAS, AVAILABLE TREATMENTS REMAIN LIMITED. AMONG THE POTENTIAL CAUSES OF LEIOMYOMAS, EARLY HORMONAL EXPOSURE DURING PERIODS OF DEVELOPMENT MAY RESULT IN DEVELOPMENTAL REPROGRAMMING VIA EPIGENETIC CHANGES THAT PERSIST IN ADULTHOOD, LEADING TO DISEASE ONSET OR PROGRESSION. RECENT DEVELOPMENTS IN UNBIASED HIGH-THROUGHPUT SEQUENCING TECHNOLOGY ENABLE POWERFUL APPROACHES TO DETECT DRIVER MUTATIONS, YIELDING NEW INSIGHTS INTO THE GENOMIC INSTABILITY OF LEIOMYOMAS. CURRENT DATA ALSO SUGGEST THAT EACH LEIOMYOMA ORIGINATES FROM THE CLONAL EXPANSION OF A SINGLE TRANSFORMED SOMATIC STEM CELL OF THE MYOMETRIUM. IN THIS REVIEW, WE PROPOSE AN INTEGRATED CELLULAR AND MOLECULAR VIEW OF THE ORIGINS OF LEIOMYOMAS, AS WELL AS PARADIGM-SHIFTING STUDIES THAT WILL LEAD TO BETTER UNDERSTANDING AND THE FUTURE DEVELOPMENT OF NON-SURGICAL TREATMENTS FOR THESE HIGHLY FREQUENT TUMORS. 2021 6 1929 46 ENVIRONMENTAL EXPOSURE, DNA METHYLATION, AND GENE REGULATION: LESSONS FROM DIETHYLSTILBESTEROL-INDUCED CANCERS. DNA METHYLATION IS AN EPIGENETIC MECHANISM THAT REGULATES CHROMOSOMAL STABILITY AND GENE EXPRESSION. ABNORMAL DNA METHYLATION PATTERNS HAVE BEEN OBSERVED IN MANY TYPES OF HUMAN TUMORS, INCLUDING THOSE OF THE BREAST, PROSTATE, COLON, THYROID, STOMACH, UTERUS, AND CERVIX. WE AND OTHERS HAVE SHOWN THAT EXPOSURE TO A WIDE VARIETY OF XENOBIOTICS DURING CRITICAL PERIODS OF MAMMALIAN DEVELOPMENT CAN PERSISTENTLY ALTER THE PATTERN OF DNA METHYLATION, RESULTING IN POTENTIALLY ADVERSE BIOLOGICAL EFFECTS SUCH AS ABERRANT GENE EXPRESSION. THUS, THIS EPIGENETIC MECHANISM MAY UNDERLIE THE OBSERVED INCREASED RISK IN ADULTHOOD OF SEVERAL CHRONIC DISEASES, INCLUDING CANCER, IN RESPONSE TO XENOBIOTIC EXPOSURES EARLY IN LIFE. WE PRESENT HERE THE LESSONS LEARNED FROM STUDIES ON THE EFFECTS OF PERINATAL DIETHYLSTILBESTEROL (DES) EXPOSURE ON THE METHYLATION PATTERN OF THE PROMOTERS OF SEVERAL ESTROGEN-RESPONSIVE GENES ASSOCIATED WITH THE DEVELOPMENT OF REPRODUCTIVE ORGANS. PERINATAL DES EXPOSURE, WHICH INDUCES EPITHELIAL TUMORS OF THE UTERUS IN MICE AND IS ASSOCIATED WITH SEVERAL REPRODUCTIVE TRACT ABNORMALITIES AND INCREASED VAGINAL AND CERVICAL CANCER RISK IN WOMEN, PROVIDES A CLEAR EXAMPLE OF HOW ESTROGENIC XENOBIOTIC EXPOSURE DURING A CRITICAL PERIOD OF DEVELOPMENT CAN ABNORMALLY DEMETHYLATE DNA SEQUENCES DURING ORGAN DEVELOPMENT AND POSSIBLY INCREASE CANCER RISK LATER IN LIFE. IN ADDITION, NUTRITIONAL FACTORS AND STRESS MAY ALSO ALTER DNA METHYLATION DURING EARLY LIFE AND MODULATE THE RISK OF CANCER AND OTHER CHRONIC DISEASES IN ADULTHOOD. WE SUGGEST THAT DNA METHYLATION STATUS MAY BE INFLUENCED BY ENVIRONMENTAL EXPOSURES IN EARLY LIFE, LEADING TO INCREASED RISK OF CANCER IN ADULTHOOD. 2003 7 2086 37 EPIGENETIC DYSREGULATION IN ENDOMETRIOSIS: IMPLICATIONS FOR PATHOPHYSIOLOGY AND THERAPEUTICS. ENDOMETRIOSIS IS A PREVALENT GYNECOLOGICAL CONDITION ASSOCIATED WITH PELVIC PAIN AND INFERTILITY. DESPITE MORE THAN A CENTURY OF RESEARCH, THE ETIOLOGY OF ENDOMETRIOSIS STILL ELUDES SCIENTIFIC CONSENSUS. THIS LACK OF CLARITY HAS RESULTED IN SUBOPTIMAL PREVENTION, DIAGNOSIS, AND TREATMENT OPTIONS. EVIDENCE OF GENETIC CONTRIBUTORS TO ENDOMETRIOSIS IS INTERESTING BUT LIMITED; HOWEVER, SIGNIFICANT PROGRESS HAS BEEN MADE IN RECENT YEARS IN IDENTIFYING EPIGENETIC ROLE IN THE PATHOGENESIS OF ENDOMETRIOSIS THROUGH CLINICAL STUDIES, IN VITRO CELL CULTURE EXPERIMENTS, AND IN VIVO ANIMAL MODELS. THE PREDOMINANT FINDINGS INCLUDE ENDOMETRIOSIS-RELATED DIFFERENTIAL EXPRESSION OF DNA METHYLTRANSFERASES AND DEMETHYLASES, HISTONE DEACETYLASES, METHYLTRANSFERASES, AND DEMETHYLASES, AND REGULATORS OF CHROMATIN ARCHITECTURE. THERE IS ALSO AN EMERGING ROLE FOR MIRNAS IN THE CONTROL OF EPIGENETIC REGULATORS IN THE ENDOMETRIUM AND ENDOMETRIOSIS. CHANGES IN THESE EPIGENETIC REGULATORS RESULT IN DIFFERENTIAL CHROMATIN ORGANIZATION AND DNA METHYLATION WITH CONSEQUENCES FOR GENE EXPRESSION INDEPENDENT OF A GENETIC SEQUENCE. EPIGENETICALLY ALTERED EXPRESSION OF GENES RELATED TO STEROID HORMONE PRODUCTION AND SIGNALING, IMMUNE REGULATION, AND ENDOMETRIAL CELL IDENTITY AND FUNCTION HAVE ALL BEEN IDENTIFIED AND APPEAR TO PLAY INTO THE PATHOPHYSIOLOGICAL MECHANISMS OF ENDOMETRIOSIS AS WELL AS RESULTING INFERTILITY. THIS REVIEW SUMMARIZES AND CRITICALLY DISCUSSES EARLY SEMINAL FINDINGS, THE EVER-GROWING RECENT EVIDENCE OF EPIGENETIC CONTRIBUTIONS TO THE PATHOPHYSIOLOGY OF ENDOMETRIOSIS, AND IMPLICATIONS FOR PROPOSED EPIGENETICALLY TARGETED THERAPEUTICS. 2023 8 3005 38 GENETIC, EPIGENETIC, AND STEROIDOGENIC MODULATION MECHANISMS IN ENDOMETRIOSIS. ENDOMETRIOSIS IS A CHRONIC GYNECOLOGICAL DISEASE, AFFECTING UP TO 10% OF REPRODUCTIVE-AGE WOMEN. THE EXACT CAUSE OF THE DISEASE IS UNKNOWN; HOWEVER, IT IS A HERITABLE CONDITION AFFECTED BY MULTIPLE GENETIC, EPIGENETIC, AND ENVIRONMENTAL FACTORS. PREVIOUS STUDIES REPORTED VARIATIONS IN THE EPIGENETIC PATTERNS OF NUMEROUS GENES KNOWN TO BE INVOLVED IN THE ABERRANT MODULATION OF CELL CYCLE STEROIDOGENESIS, ABNORMAL HORMONAL, IMMUNE AND INFLAMMATORY STATUS IN ENDOMETRIOSIS, APOPTOSIS, ADHESION, ANGIOGENESIS, PROLIFERATION, IMMUNE AND INFLAMMATORY PROCESSES, RESPONSE TO HYPOXIA, STEROIDOGENIC PATHWAY AND HORMONE SIGNALING ARE INVOLVED IN THE PATHOGENESIS OF ENDOMETRIOSIS. ACCUMULATING EVIDENCE SUGGEST THAT VARIOUS EPIGENETIC ABERRATIONS MAY CONTRIBUTE TO THE PATHOGENESIS OF ENDOMETRIOSIS. AMONG THEM, DNA METHYLTRANSFERASES, HISTONE DEACETYLATORS, AND NON-CODING MICRORNAS DEMONSTRATE DIFFERENTIAL EXPRESSION WITHIN ENDOMETRIOTIC LESIONS AND IN THE ENDOMETRIUM OF PATIENTS WITH ENDOMETRIOSIS. IT HAS BEEN INDICATED THAT THE IDENTIFICATION OF EPIGENETIC DIFFERENCES WITHIN THE DNA OR HISTONE PROTEINS MAY CONTRIBUTE TO THE DISCOVERY OF A USEFUL PROGNOSTIC BIOMARKER, WHICH COULD AID IN THE FUTURE EARLIER DETECTION, TIMELY DIAGNOSIS, AND INITIATION OF A NEW APPROACH TO THE TREATMENT OF ENDOMETRIOSIS, AS WELL AS INFORM US ABOUT THE EFFECTIVENESS OF TREATMENT AND THE STAGE OF THE DISEASE. AS THE ETIOLOGY OF ENDOMETRIOSIS IS HIGHLY COMPLEX AND STILL FAR FROM BEING FULLY ELUCIDATED, THE PRESENTED REVIEW FOCUSES ON DIFFERENT APPROACHES TO IDENTIFY THE GENETIC AND EPIGENETIC LINKS OF ENDOMETRIOSIS AND ITS PATHOGENESIS. 2020 9 3003 46 GENETIC, EPIGENETIC AND STEM CELL ALTERATIONS IN ENDOMETRIOSIS: NEW INSIGHTS AND POTENTIAL THERAPEUTIC PERSPECTIVES. HUMAN ENDOMETRIUM IS A HIGHLY DYNAMIC TISSUE, UNDERGOING PERIODIC GROWTH AND REGRESSION AT EACH MENSTRUAL CYCLE. ENDOMETRIOSIS IS A FREQUENT CHRONIC PATHOLOGICAL STATUS CHARACTERIZED BY ENDOMETRIAL TISSUE WITH AN ECTOPIC LOCALIZATION, CAUSING PELVIC PAIN AND INFERTILITY AND A VARIABLE CLINICAL PRESENTATION. IN ADDITION, THERE IS WELL-ESTABLISHED EVIDENCE THAT, ALTHOUGH ENDOMETRIOSIS IS CONSIDERED BENIGN, IT IS ASSOCIATED WITH AN INCREASED RISK OF MALIGNANT TRANSFORMATION IN APPROXIMATELY 1.0% OF AFFECTED WOMEN, WITH THE INVOLVEMENT OF MULTIPLE PATHWAYS OF DEVELOPMENT. INCREASING EVIDENCE SUPPORTS A KEY CONTRIBUTION OF DIFFERENT STEM/PROGENITOR CELL POPULATIONS NOT ONLY IN THE CYCLIC REGENERATION OF EUTOPIC ENDOMETRIUM, BUT ALSO IN THE PATHOGENESIS OF AT LEAST SOME TYPES OF ENDOMETRIOSIS. EVIDENCE HAS ARISEN FROM EXPERIMENTS IN ANIMAL MODELS OF DISEASE THROUGH DIFFERENT KINDS OF ASSAYS (INCLUDING CLONOGENICITY, THE LABEL-RETAINING CELL APPROACH, THE ANALYSIS OF UNDIFFERENTIATION MARKERS), AS WELL AS FROM DESCRIPTIVE STUDIES ON ECTOPIC AND EUTOPIC TISSUE SAMPLES HARVESTED FROM AFFECTED WOMEN. CHANGES IN STEM CELL POPULATIONS IN ENDOMETRIOTIC LESIONS ARE ASSOCIATED WITH GENETIC AND EPIGENETIC ALTERATIONS, INCLUDING IMBALANCE OF MIRNA EXPRESSION, HISTONE AND DNA MODIFICATIONS AND CHROMOSOMAL ABERRATIONS. THE PRESENT SHORT REVIEW MAINLY SUMMARIZES THE LATEST OBSERVATIONS CONTRIBUTING TO THE CURRENT KNOWLEDGE REGARDING THE PRESENCE AND THE POTENTIAL CONTRIBUTION OF STEM/PROGENITOR CELLS IN EUTOPIC ENDOMETRIUM AND THE AETIOLOGY OF ENDOMETRIOSIS, TOGETHER WITH A REPORT OF THE MOST RECENTLY IDENTIFIED GENETIC AND EPIGENETIC ALTERATIONS IN ENDOMETRIOSIS. WE ALSO DESCRIBE THE POTENTIAL ADVANTAGES OF SINGLE CELL MOLECULAR PROFILING IN ENDOMETRIUM AND IN ENDOMETRIOTIC LESIONS. ALL THESE DATA CAN HAVE CLINICAL IMPLICATIONS AND PROVIDE A BASIS FOR NEW POTENTIAL THERAPEUTIC APPLICATIONS. 2014 10 5892 48 SYSTEMS GENETICS VIEW OF ENDOMETRIOSIS: A COMMON COMPLEX DISORDER. ENDOMETRIOSIS IS A CONDITION IN WHICH CELLS DERIVED FROM THE ENDOMETRIUM GROW OUTSIDE THE UTERUS, E.G. IN THE PERITONEUM (EXTERNAL GENITAL ENDOMETRIOSIS). AS THESE CELLS ARE UNDER THE INFLUENCE OF FEMALE HORMONES, MAJOR SYMPTOMS OF ENDOMETRIOSIS ARE PAIN, ESPECIALLY DURING THE CYCLE, AND INFERTILITY. NUMEROUS HYPOTHESES FOR THE FORMATION OF ENDOMETRIOSIS CAN BE FOUND IN THE LITERATURE, BUT THERE IS GROWING EVIDENCE OF SERIOUS GENETIC CONTRIBUTIONS TO ENDOMETRIOSIS SUSCEPTIBILITY. THE INVOLVEMENT OF GENES, STEROID HORMONE METABOLISM, IMMUNOLOGICAL REACTIONS, RECEPTOR FORMATION, INFLAMMATION, PROLIFERATION, APOPTOSIS, INTERCELLULAR ADHESION, CELL INVASION AND ANGIOGENESIS AS WELL AS GENES REGULATING THE ACTIVITY OF AFOREMENTIONED ENZYMES HAVE BEEN SUGGESTED. SOME MORE RECENTLY SUGGESTED CANDIDATE GENES PICKED UP IN GENOME-WIDE ASSOCIATION STUDIES ARE INVOLVED IN ONCOGENESIS, METAPLASIA OF ENDOMETRIUM CELLS AND PATHWAYS OF EMBRYONIC DEVELOPMENT OF THE FEMALE REPRODUCTIVE SYSTEM. HOWEVER, GENE MUTATIONS PROVEN TO BE CAUSATIVE FOR ENDOMETRIOSIS HAVE NOT BEEN IDENTIFIED SO FAR, EVEN THOUGH THE ABNORMAL EXPRESSION OF CANDIDATE GENES FOR ENDOMETRIOSIS COULD BE PROVOKED BY DIFFERENT EPIGENETIC MODIFICATIONS INCLUDING DNA METHYLATION, HETEROCHROMATIZATION OR INTRODUCTION OF REGULATORY MIRNA. WE HYPOTHESIZE THAT ENDOMETRIOSIS IS INDUCED BY A COMBINATION OF ABNORMAL GENETIC AND/OR EPIGENETIC MUTATIONS: THE LATTER PAVE THE WAY FOR PATHOLOGICAL CHANGES WHICH BECOME IRREVERSIBLE, AND ACCORDING TO THE "EPIGENETIC LANDSCAPE" THEORY, THIS PROCEEDS TO THE TYPICAL CLINICAL MANIFESTATIONS. TWO STAGES IN THE ENDOMETRIOSIS PATHWAY ARE SUGGESTED: (1) INDUCTION OF PRIMARY ENDOMETRIAL CELLS TOWARD ENDOMETRIOSIS, AND (2) IMPLANTATION AND PROGRESSION OF THESE CELLS INTO ENDOMETRIOSIS LESIONS. THE MODEL FAVORS ENDOMETRIOSIS AS AN OUTGROWTH OF PRIMARY CELLS DIFFERENT IN THEIR ORIGIN, CANALIZATION OF PATHOLOGICAL PROCESSES, MANIFESTATION DIVERSITY PROVOKED BY UNIQUE GENETIC BACKGROUND AND EPIGENETIC INFLUENCES, WHICH RESULT IN MANY DIFFERENT CLINICAL FORMS OF THE DISEASE. 2015 11 2412 58 EPIGENETIC SIDE-EFFECTS OF COMMON PHARMACEUTICALS: A POTENTIAL NEW FIELD IN MEDICINE AND PHARMACOLOGY. THE TERM "EPIGENETICS" REFERS TO DNA AND CHROMATIN MODIFICATIONS THAT PERSIST FROM ONE CELL DIVISION TO THE NEXT, DESPITE A LACK OF CHANGE IN THE UNDERLYING DNA SEQUENCE. THE "EPIGENOME" REFERS TO THE OVERALL EPIGENETIC STATE OF A CELL, AND SERVES AS AN INTERFACE BETWEEN THE ENVIRONMENT AND THE GENOME. THE EPIGENOME IS DYNAMIC AND RESPONSIVE TO ENVIRONMENTAL SIGNALS NOT ONLY DURING DEVELOPMENT, BUT ALSO THROUGHOUT LIFE; AND IT IS BECOMING INCREASINGLY APPARENT THAT CHEMICALS CAN CAUSE CHANGES IN GENE EXPRESSION THAT PERSIST LONG AFTER EXPOSURE HAS CEASED. HERE WE PRESENT THE HYPOTHESIS THAT COMMONLY-USED PHARMACEUTICAL DRUGS CAN CAUSE SUCH PERSISTENT EPIGENETIC CHANGES. DRUGS MAY ALTER EPIGENETIC HOMEOSTASIS BY DIRECT OR INDIRECT MECHANISMS. DIRECT EFFECTS MAY BE CAUSED BY DRUGS WHICH AFFECT CHROMATIN ARCHITECTURE OR DNA METHYLATION. FOR EXAMPLE THE ANTIHYPERTENSIVE HYDRALAZINE INHIBITS DNA METHYLATION. AN EXAMPLE OF AN INDIRECTLY ACTING DRUG IS ISOTRETINOIN, WHICH HAS TRANSCRIPTION FACTOR ACTIVITY. A TWO-TIER MECHANISM IS POSTULATED FOR INDIRECT EFFECTS IN WHICH ACUTE EXPOSURE TO A DRUG INFLUENCES SIGNALING PATHWAYS THAT MAY LEAD TO AN ALTERATION OF TRANSCRIPTION FACTOR ACTIVITY AT GENE PROMOTERS. THIS STIMULATION RESULTS IN THE ALTERED EXPRESSION OF RECEPTORS, SIGNALING MOLECULES, AND OTHER PROTEINS NECESSARY TO ALTER GENETIC REGULATORY CIRCUITS. WITH MORE CHRONIC EXPOSURE, CELLS ADAPT BY AN UNKNOWN HYPOTHETICAL PROCESS THAT RESULTS IN MORE PERMANENT MODIFICATIONS TO DNA METHYLATION AND CHROMATIN STRUCTURE, LEADING TO ENDURING ALTERATION OF A GIVEN EPIGENETIC NETWORK. THEREFORE, ANY EPIGENETIC SIDE-EFFECT CAUSED BY A DRUG MAY PERSIST AFTER THE DRUG IS DISCONTINUED. IT IS FURTHER PROPOSED THAT SOME IATROGENIC DISEASES SUCH AS TARDIVE DYSKINESIA AND DRUG-INDUCED SLE ARE EPIGENETIC IN NATURE. IF THIS HYPOTHESIS IS CORRECT THE CONSEQUENCES FOR MODERN MEDICINE ARE PROFOUND, SINCE IT WOULD IMPLY THAT OUR CURRENT UNDERSTANDING OF PHARMACOLOGY IS AN OVERSIMPLIFICATION. WE PROPOSE THAT EPIGENETIC SIDE-EFFECTS OF PHARMACEUTICALS MAY BE INVOLVED IN THE ETIOLOGY OF HEART DISEASE, CANCER, NEUROLOGICAL AND COGNITIVE DISORDERS, OBESITY, DIABETES, INFERTILITY, AND SEXUAL DYSFUNCTION. IT IS SUGGESTED THAT A SYSTEMS BIOLOGY APPROACH EMPLOYING MICROARRAY ANALYSES OF GENE EXPRESSION AND METHYLATION PATTERNS CAN LEAD TO A BETTER UNDERSTANDING OF LONG-TERM SIDE-EFFECTS OF DRUGS, AND THAT IN THE FUTURE, EPIGENETIC ASSAYS SHOULD BE INCORPORATED INTO THE SAFETY ASSESSMENT OF ALL PHARMACEUTICAL DRUGS. THIS NEW APPROACH TO PHARMACOLOGY HAS BEEN TERMED "PHAMACOEPIGENOMICS", THE IMPACT OF WHICH MAY BE EQUAL TO OR GREATER THAN THAT OF PHARMACOGENETICS. WE PROVIDE HERE AN OVERVIEW OF THIS POTENTIALLY MAJOR NEW FIELD IN PHARMACOLOGY AND MEDICINE. 2009 12 1844 51 EFFECTS OF THE LIFESTYLE HABITS IN BREAST CANCER TRANSCRIPTIONAL REGULATION. THROUGH RESEARCH CARRIED OUT IN THE LAST 25 YEARS ABOUT THE BREAST CANCER ETIOLOGY, IT HAS BEEN POSSIBLE TO ESTIMATE THAT LESS THAN 10 % OF PATIENTS WHO ARE DIAGNOSED WITH THE CONDITION ARE CARRIERS OF SOME GERMLINE OR SOMATIC MUTATION. THE CLINICAL REPORTS OF BREAST CANCER PATIENTS WITH HEALTHY TWINS AND THE DEVELOPMENT OF DISEASE IN WOMEN WITHOUT HIGH PENETRANCE MUTATIONS DETECTED, WARN THE PARTICIPATION MORE FACTORS IN THE TRANSFORMATION PROCESS. THE HIGH INCIDENCE OF MAMMARY ADENOCARCINOMA IN THE MODERN WOMAN AND THE URGENT NEED FOR NEW METHODS OF PREVENTION AND EARLY DETECTION HAVE DEMANDED MORE INFORMATION ABOUT THE ROLE THAT ENVIRONMENT AND LIFESTYLE HAVE ON THE TRANSFORMATION OF MAMMARY GLAND EPITHELIAL CELLS. OBESITY, ALCOHOLISM AND SMOKING ARE FACTORS THAT HAVE SHOWN A CLOSE CORRELATION WITH THE RISK OF DEVELOPING BREAST CANCER. AND ALTHOUGH THESE CONDITIONS AFFECT DIFFERENT CELL REGULATION LEVELS, THE STUDY OF ITS EFFECTS IN THE MECHANISMS OF TRANSCRIPTIONAL AND EPIGENETIC REGULATION IS CONSIDERED CRITICAL FOR A BETTER UNDERSTANDING OF THE LOSS OF IDENTITY OF EPITHELIAL CELLS DURING CARCINOGENESIS OF THIS TISSUE. THE MAIN OBJECTIVE OF THIS REVIEW WAS TO ESTABLISH THE IMPORTANCE OF CHANGES OCCURRING TO TRANSCRIPTIONAL LEVEL IN THE MAMMARY GLAND AS A CONSEQUENCE OF ACUTE OR CHRONIC EXPOSURE TO HARMFUL PRODUCTS SUCH AS OBESITY-CAUSING FOODS, ETHANOL AND CIGARETTE SMOKE COMPONENTS. AT ANALYZE THE MAIN STUDIES RELATED TO TOPIC, IT HAS CONCLUDED THAT THE UNDERSTANDING OF EFFECTS CAUSED BY THE LIFESTYLE FACTORS IN PERFORMANCE OF THE TRANSCRIPTIONAL MECHANISMS THAT DETERMINE GENE EXPRESSION OF THE MAMMARY GLAND EPITHELIAL CELLS, MAY HELP EXPLAIN THE DEVELOPMENT OF THIS DISEASE IN WOMEN WITHOUT GENETIC PROPENSITY AND DIFFERENT PHENOTYPIC MANIFESTATIONS OF THIS CANCER TYPE. 2016 13 5378 19 RECENT INSIGHTS ON THE GENETICS AND EPIGENETICS OF ENDOMETRIOSIS. ENDOMETRIOSIS IS A GYNECOLOGIC DISEASE AFFECTING UP TO 10% OF THE WOMEN AND A MAJOR CAUSE OF PAIN AND INFERTILITY. IT IS CHARACTERIZED BY THE IMPLANTATION OF FUNCTIONAL ENDOMETRIAL TISSUE AT ECTOPIC POSITIONS GENERALLY WITHIN THE PERITONEUM. THIS COMPLEX DISEASE HAS AN IMPORTANT GENETIC COMPONENT WITH A HERITABILITY ESTIMATED AT AROUND 50%. THIS REVIEW AIMS AT PROVIDING RECENT INSIGHTS INTO THE GENETIC BASES OF ENDOMETRIOSIS, AND PRESENTS A DETAILED OVERVIEW OF EVIDENCE OF EPIGENETIC ALTERATIONS SPECIFIC TO THIS DISEASE. IN THE FUTURE, THESE ALTERATIONS MAY CONSTITUTE THERAPEUTIC TARGETS FOR PHARMACOLOGICAL COMPOUNDS ABLE TO MODIFY THE EPIGENETIC CODE. 2017 14 1202 39 COULD DNA HYDROXYMETHYLATION BE CRUCIAL IN INFLUENCING STEROID HORMONE SIGNALING IN ENDOMETRIAL BIOLOGY AND ENDOMETRIOSIS? ENDOMETRIOSIS AFFECTS 10% OF REPRODUCTIVE-AGED WOMEN. IT IS CHARACTERIZED BY THE GROWTH OF THE ENDOMETRIUM, OUTSIDE THE UTERUS AND IS ASSOCIATED WITH INFERTILITY AND CHRONIC ABDOMINAL PAIN. LACK OF NONINVASIVE DIAGNOSTIC TOOLS AND EARLY SCREENING TESTS RESULTS IN DELAYED TREATMENT AND SUBSEQUENTLY INCREASED DISEASE SEVERITY. ENDOMETRIOSIS IS A DISEASE ASSOCIATED WITH A DEREGULATED HORMONAL RESPONSE, THEREFORE, UNDERSTANDING THE MOLECULAR MECHANISMS THAT GOVERN THIS HORMONAL INTERPLAY IS OF PARAMOUNT IMPORTANCE. DNA METHYLATION IS AN EPIGENETIC MARK THAT REGULATES GENE EXPRESSION AND IS OFTEN ASSOCIATED WITH GENES THAT CODE FOR STEROID RECEPTORS AND ENZYMES ASSOCIATED WITH ESTROGEN SYNTHESIS AND METABOLISM IN ENDOMETRIOSIS. DNA HYDROXYMETHYLATION, WHICH IS STRUCTURALLY SIMILAR TO METHYLATION BUT FUNCTIONALLY DIFFERENT, IS A BIOLOGICALLY CRITICAL MECHANISM THAT IS ALSO KNOWN TO REGULATE GENE EXPRESSION. TEN ELEVEN TRANSLOCATION (TET) PROTEINS MEDIATE HYDROXYMETHYLATION. HOWEVER, THE ROLE OF DNA HYDROXYMETHYLATION OR TETS IN THE ENDOMETRIUM REMAINS RELATIVELY UNEXPLORED. CURRENTLY, THE "GOLD STANDARD" TECHNIQUE USED TO STUDY METHYLATION PATTERNS IS BISULFITE GENOMIC SEQUENCING. THIS TECHNIQUE ALSO DETECTS HYDROXYMETHYLATION BUT FAILS TO DISTINGUISH BETWEEN THE TWO, THEREBY LIMITING OUR UNDERSTANDING OF THESE TWO PROCESSES. THE PRESENCE OF TETS IN THE MALE AND FEMALE REPRODUCTIVE TRACT AND ITS CONTRIBUTION TO ENDOMETRIAL CANCER MAKES IT AN IMPORTANT FACTOR TO STUDY IN ENDOMETRIOSIS. THIS REVIEW SUMMARIZES THE ROLE OF DNA METHYLATION IN ABERRANT STEROID HORMONE SIGNALING AND HYPOTHESIZES THAT HYDROXYMETHYLATION COULD BE A FACTOR INFLUENCING HORMONAL INSTABILITY SEEN IN ENDOMETRIOSIS. 2020 15 2541 31 EPIGENETICS IN KIDNEY DEVELOPMENT AND RENAL DISEASE. THE STUDY OF EPIGENETICS IS INTIMATELY LINKED AND INSEPARABLE FROM DEVELOPMENTAL BIOLOGY. MANY OF THE GENES THAT IMPRINT EPIGENETIC INFORMATION ON CHROMATIN FUNCTION DURING THE SPECIFICATION OF CELL LINEAGES IN THE DEVELOPING EMBRYO. THESE INCLUDE THE HISTONE METHYLTRANSFERASES AND THEIR COFACTORS OF THE POLYCOMB AND TRITHORAX GENE FAMILIES. HOW HISTONE METHYLATION IS ESTABLISHED AND WHAT REGULATES THE TISSUE AND LOCUS SPECIFICITY OF HISTONE METHYLATION IS AN EMERGING AREA OF RESEARCH. THE EMBRYONIC KIDNEY IS USED AS A MODEL TO UNDERSTAND HOW DNA-BINDING PROTEINS CAN SPECIFY CELL LINEAGES AND HOW SUCH PROTEINS INTERACT DIRECTLY WITH THE HISTONE METHYLATION MACHINERY TO GENERATE A UNIQUE EPIGENOME FOR PARTICULAR TISSUES AND CELL TYPES. IN ADULT TISSUES, HISTONE METHYLATION MARKS MUST BE MAINTAINED FOR NORMAL GENE EXPRESSION PATTERNS. IN CHRONIC AND ACUTE RENAL DISEASE, EPIGENETIC MARKS ARE BEING CHARACTERIZED AND CORRELATED WITH THE ESTABLISHMENT OF METABOLIC MEMORY, IN PART TO EXPLAIN THE PERSISTENCE OF PATHOLOGIES EVEN WHEN OPTIMAL TREATMENT MODALITIES ARE USED. THUS, THE STATE OF THE EPIGENOME IN ADULT CELLS MUST BE CONSIDERED WHEN ATTEMPTING TO ALLEVIATE OR ALTER GENE EXPRESSION PATTERNS IN DISEASE. 2015 16 733 31 CANCER EPIGENETICS: LINKING BASIC BIOLOGY TO CLINICAL MEDICINE. CANCER EVOLUTION AT ALL STAGES IS DRIVEN BY BOTH EPIGENETIC ABNORMALITIES AS WELL AS GENETIC ALTERATIONS. DYSREGULATION OF EPIGENETIC CONTROL EVENTS MAY LEAD TO ABNORMAL PATTERNS OF DNA METHYLATION AND CHROMATIN CONFIGURATIONS, BOTH OF WHICH ARE CRITICAL CONTRIBUTORS TO THE PATHOGENESIS OF CANCER. THESE EPIGENETIC ABNORMALITIES ARE SET AND MAINTAINED BY MULTIPLE PROTEIN COMPLEXES AND THE INTERPLAY BETWEEN THEIR INDIVIDUAL COMPONENTS INCLUDING DNA METHYLATION MACHINERY, HISTONE MODIFIERS, PARTICULARLY, POLYCOMB (PCG) PROTEINS, AND CHROMATIN REMODELING PROTEINS. RECENT ADVANCES IN GENOME-WIDE TECHNOLOGY HAVE REVEALED THAT THE INVOLVEMENT OF THESE DYSREGULATED EPIGENETIC COMPONENTS APPEARS TO BE EXTENSIVE. MOREOVER, THERE IS A GROWING CONNECTION BETWEEN EPIGENETIC ABNORMALITIES IN CANCER AND CONCEPTS CONCERNING STEM-LIKE CELL SUBPOPULATIONS AS A DRIVING FORCE FOR CANCER. EMERGING DATA SUGGEST THAT ASPECTS OF THE EPIGENETIC LANDSCAPE INHERENT TO NORMAL EMBRYONIC AND ADULT STEM/PROGENITOR CELLS MAY HELP FOSTER, UNDER THE STRESS OF CHRONIC INFLAMMATION OR ACCUMULATING REACTIVE OXYGEN SPECIES, EVOLUTION OF MALIGNANT SUBPOPULATIONS. FINALLY, UNDERSTANDING MOLECULAR MECHANISMS INVOLVED IN INITIATION AND MAINTENANCE OF EPIGENETIC ABNORMALITIES IN ALL TYPES OF CANCER HAS GREAT POTENTIAL FOR TRANSLATIONAL PURPOSES. THIS IS ALREADY EVIDENT FOR EPIGENETIC BIOMARKER DEVELOPMENT, AND FOR PHARMACOLOGICAL TARGETING AIMED AT REVERSING CANCER-SPECIFIC EPIGENETIC ALTERATIONS. 2011 17 738 38 CANCER SUSCEPTIBILITY: EPIGENETIC MANIFESTATION OF ENVIRONMENTAL EXPOSURES. CANCER IS A DISEASE THAT RESULTS FROM BOTH GENETIC AND EPIGENETIC CHANGES. DISCORDANT PHENOTYPES AND VARYING INCIDENCES OF COMPLEX DISEASES SUCH AS CANCER IN MONOZYGOTIC TWINS AS WELL AS GENETICALLY IDENTICAL LABORATORY ANIMALS HAVE LONG BEEN ATTRIBUTED TO DIFFERENCES IN ENVIRONMENTAL EXPOSURES. ACCUMULATING EVIDENCE INDICATES, HOWEVER, THAT DISPARITIES IN GENE EXPRESSION RESULTING FROM VARIABLE MODIFICATIONS IN DNA METHYLATION AND CHROMATIN STRUCTURE IN RESPONSE TO THE ENVIRONMENT ALSO PLAY A ROLE IN DIFFERENTIAL SUSCEPTIBILITY TO DISEASE. DESPITE A GROWING CONSENSUS ON THE IMPORTANCE OF EPIGENETICS IN THE ETIOLOGY OF CHRONIC HUMAN DISEASES, THE GENES MOST PRONE TO EPIGENETIC DYSREGULATION ARE INCOMPLETELY DEFINED. MOREOVER, NEITHER THE ENVIRONMENTAL AGENTS MOST STRONGLY AFFECTING THE EPIGENOME NOR THE CRITICAL WINDOWS OF VULNERABILITY TO ENVIRONMENTALLY INDUCED EPIGENETIC ALTERATIONS ARE ADEQUATELY CHARACTERIZED. THESE MAJOR DEFICITS IN KNOWLEDGE MARKEDLY IMPAIR OUR ABILITY TO UNDERSTAND FULLY THE ETIOLOGY OF CANCER AND THE IMPORTANCE OF THE EPIGENOME IN DIAGNOSING AND PREVENTING THIS DEVASTATING DISEASE. 2007 18 6771 33 [ACQUIRED DISORDERS AND EPIGENETICS]. EPIGENETIC MODIFICATIONS, INVOLVING DNA METHYLATION AND HISTONE MODIFICATIONS, ARE MAINTAINED UPON SOMATIC CELL REPLICATION, AND ARE FUNDAMENTAL MECHANISMS FOR CELLULAR MEMORY. DNA METHYLATION OF PROMOTER CPG ISLANDS OF TUMOR-SUPPRESSOR GENES CAN SILENCE THEIR DOWNSTREAM GENES, AND CAN BE CAUSALLY INVOLVED IN CANCER DEVELOPMENT AND PROGRESSION. SINCE THIS EFFECT IS THE SAME WITH THAT OF INACTIVATING MUTATIONS, THE NATURES OF DNA METHYLATION WERE ONCE CONSIDERED TO BE SIMILAR TO MUTATIONS. HOWEVER, RECENTLY, IT WAS REVEALED THAT A LARGE NUMBER OF EPIGENETIC ALTERATIONS ARE PRESENT IN A SINGLE CANCER CELL, THAT A LARGE NUMBER OF CELLS HAVE AN EPIGENETIC ALTERATION OF A SPECIFIC GENE IN NON-CANCEROUS, THUS POLYCLONAL, TISSUES, THAT GENE SPECIFICITY IN METHYLATION INDUCTION IS PRESENT ACCORDING TO TISSUE TYPES AND INDUCERS, AND THAT CHRONIC INFLAMMATION IS DEEPLY INVOLVED IN METHYLATION INDUCTION. THESE FACTS SUGGEST THAT EPIGENETIC ALTERATIONS OF KEY GENES INVOLVED IN ACQUIRED CHRONIC DISORDERS CAN BE PRESENT IN A SIGNIFICANT FRACTION OF CELLS IN A TISSUE, AND THUS CAN IMPAIR THE FUNCTION OF THE TISSUE. ASSOCIATIONS BETWEEN EPIGENETIC ALTERATIONS AND BEHAVIOR, MEMORY, MENTAL DISORDERS, NEUROLOGICAL DISORDERS, METABOLIC DISORDERS, ALLERGY, AUTOIMMUNE DISORDERS, AND OTHER DISORDERS HAVE BEEN REPORTED. FURTHER RESEARCH IN THE FIELD IS NECESSARY TO CLARIFY THE CAUSAL ROLES OF THESE EPIGENETIC ALTERATIONS IN DISEASE DEVELOPMENT, AND TO APPLY THE FINDINGS TO NEW STRATEGIES OF DISEASE PREVENTION, DIAGNOSIS, AND TREATMENT. 2010 19 6031 31 THE CANCER EPIGENOME: ITS ORIGINS, CONTRIBUTIONS TO TUMORIGENESIS, AND TRANSLATIONAL IMPLICATIONS. EPIGENETIC ABNORMALITIES IN LUNG AND OTHER CANCERS CONTINUE TO BE DEFINED AT A RAPID PACE. WE ARE COMING TO APPRECIATE THAT CANCERS HAVE AN "EPIGENETIC LANDSCAPE" WHEREIN GENES VULNERABLE TO ABNORMALITIES, SUCH AS PROMOTER DNA HYPERMETHYLATION AND ASSOCIATED GENE SILENCING, TEND TO RESIDE IN DEFINED NUCLEAR POSITIONS AND CHROMOSOME DOMAINS AND RELATIONSHIPS TO CHROMATIN REGULATION, WHICH FACILITATES STATES OF STEM CELL RENEWAL. THESE SAME GENES AND DOMAINS ARE ALSO VULNERABLE TO EPIGENETIC ABNORMALITIES INDUCED BY FACTORS TO WHICH CELLS ARE EXPOSED DURING CANCER RISK STATES, SUCH AS CHRONIC INFLAMMATION. WE CAN USE ALL OF THIS BASIC INFORMATION FOR TRANSLATIONAL PURPOSES IN TERMS OF DERIVING BIOMARKERS FOR CANCER RISK STATES AND DETECTION AND THERAPEUTIC STRATEGIES. 2012 20 1641 36 DOES GUT-BREAST MICROBIOTA AXIS ORCHESTRATES CANCER PROGRESSION? BREAST CANCER, EVEN TODAY, CAN CAUSE DEATH. THEREFORE, PREVENTION AND EARLY DETECTION ARE FUNDAMENTAL FACTORS. THE MECHANISMS THAT FAVOUR IT ARE GENETIC AND EPIGENETIC, AND SEEM TO PLAY A SIGNIFICANT ROLE; ALSO, THE MICROBIOTA CAN CHANGE ESTROGEN LEVELS AND CAN INDUCE CHRONIC INFLAMMATION IN THE NEOPLASTIC SITE, ALTERNATING THE BALANCE BETWEEN PROLIFERATION AND CELL DEATH. ACTIVATED STEROID HORMONE RECEPTORS INDUCE TRANSCRIPTION OF GENES THAT ENCODE FOR PROTEINS INVOLVED IN CELL PROLIFERATION AND ACTIVATE ANOTHER TRANSDUCTION PATHWAY, INDUCING CELL CYCLE PROGRESSION AND CELL MIGRATION. THESE IMPORTANT STUDIES HAVE ALLOWED TO DEVELOP THERAPIES WITH SELECTIVE MODULATORS OF ESTROGEN RECEPTORS (SERMS), ABLE TO BLOCK THEIR PROLIFERATIVE AND PRO-TUMORIGENIC ACTION. OF FUNDAMENTAL IMPORTANCE IS ALSO THE ROLE PLAYED BY THE MICROBIOTA IN REGULATING THE METABOLISM OF ESTROGENS AND THEIR LEVELS IN THE BLOOD. THERE ARE MICROBIAL POPULATIONS THAT ARE ABLE TO PROMOTE THE DEVELOPMENT OF BREAST CANCER, THROUGH THE PRODUCTION OF ENZYMES RESPONSIBLE FOR THE DECONJUGATION OF ESTROGENS, THE INCREASE OF THESE IN THE INTESTINE, SUBSEQUENT CIRCULATION AND MIGRATION TO OTHER LOCATIONS, SUCH AS THE UDDER. OTHER MICROBIAL POPULATIONS ARE, INSTEAD, ABLE TO SYNTHESIZE ESTROGEN COMPOUNDS OR MIMIC ESTROGENIC ACTION, AND INTERFERE WITH THE METABOLISM OF DRUGS, AFFECTING THE OUTCOME OF THERAPIES. THE MICROBIAL COMPOSITION OF THE INTESTINE AND HORMONAL METABOLISM DEPEND LARGELY ON EATING HABITS; THE CONSUMPTION OF FATS AND PROTEINS FAVOURS THE INCREASE OF ESTROGEN IN THE BLOOD, UNLIKE A DIET RICH IN FIBER. THEREFORE, IN-DEPTH KNOWLEDGE OF THE MICROBIOTA PRESENT IN THE INTESTINE-BREAST AXIS COULD, IN THE FUTURE, ENCOURAGE THE DEVELOPMENT OF NEW DIAGNOSTIC AND THERAPEUTIC APPROACHES TO BREAST CANCERS. 2022