1 3934 260 LIVER TUMOR INDUCTION. THE SIGNIFICANCE OF THE DEVELOPMENT OF NODULAR LIVER LESIONS IN RODENTS FOLLOWING THE ADMINISTRATION OF TEST AGENTS RAISES SEVERAL QUESTIONS WHICH COULD BE PLACED IN ONE OF TWO GENERAL CATEGORIES: DIAGNOSTIC AND INTERPRETATIONAL. FROM A DIAGNOSTIC POINT OF VIEW, THE PROPER CLASSIFICATION OF LIVER TUMORS INTO A BENIGN AND MALIGNANT CATEGORY HAS TO BE BASED ON THE DIRECT CORRELATION BETWEEN THE MORPHOLOGY AND THE BIOLOGIC BEHAVIOR OF THE LESIONS. THEREFORE, EXTREME CARE SHOULD BE TAKEN TO SEPARATE THE MALIGNANT TUMORS FROM THE BENIGN AND THE BENIGN NEOPLASIA FROM THE HYPERPLASIA. THE SUBSTITUTION OF THE TERM "NEOPLASTIC NODULE" FOR HYPERPLASTIC NODULE IN RATS IS MISLEADING. MOST OF THESE NODULES, WHEN INDUCED UNDER SPECIAL EXPERIMENTAL CONDITIONS, MAY REGRESS OR REMODEL AND THUS THEY ARE NOT NEOPLASTIC IN NATURE. CHRONIC CARCINOGENICITY BIOASSAYS SHOULD INCLUDE "STOP" TYPE OF TREATMENT LEAVING ENOUGH OF THE OBSERVATIONAL TIME TO ESTABLISH THE FATE OF INDUCED NODULAR LESIONS. THE INDUCTION OF HISTOCHEMICALLY CHANGED FOCI CAN SERVE ONLY AS AN INDICATION OF POTENTIAL HEPATOCARCINOGENICITY AND SHOULD NOT BE EQUATED WITH THE INDUCTION OF BONA FIDE CANCER. THE BIOLOGIC INTERPRETATION OF NODULAR LIVER LESIONS, ESPECIALLY IN MICE, NEEDS FURTHER SCRUTINY BECAUSE THESE LESIONS HAVE A TENDENCY TO DEVELOP SPONTANEOUSLY WITH HIGH INCIDENCE IN SOME STRAINS. THIS CHARACTERISTIC THEN RAISES THE QUESTION AS TO THE MECHANISM BY WHICH VARIOUS AGENTS AUGMENT AND/OR ACCELERATE THE DEVELOPMENT OF SUCH TUMORS. IS THIS ACTION PRIMARILY PROMOTING OR INITIATING IN NATURE OR DOES IT REPRESENT THE INDUCTION OF TUMORS DE NOVO? THE ANSWER TO THIS DILEMMA MAY HAVE A DECISIVE BEARING ON CARCINOGENIC RISK ASSESSMENT AND THE TYPE OF REGULATORY ACTION, SINCE THE PROMOTING AGENTS POSSESS A THRESHOLD EFFECT AND THE PROMOTED CHANGES MAY REGRESS FOLLOWING WITHDRAWAL OF TREATMENT. THE INTERPRETATION OF HEPATOCARCINOGENESIS IS FURTHER COMPLICATED BY THE FACT THAT SEVERAL FACTORS, SUCH AS SEX HORMONAL ENVIRONMENT, INCREASED MITOTIC ACTIVITY FOLLOWING AN EXCESSIVE LOSS OF PARENCHYMAL CELLS, DEGREE OF CALORIC INTAKE, ENZYMATIC COMPLEMENT, AND ANIMALS' AGE AT THE TIME OF THE EXPOSURE TO A TEST AGENT, MAY INFLUENCE THE OUTCOME OF LIVER TUMOR DEVELOPMENT BY MODULATING "INITIATION" AND/OR "PROMOTION" OF CARCINOGENESIS. BROAD FLUCTUATION IN THE HISTORIC INCIDENCE OF LIVER TUMORS FURTHER COMPOUNDS THE COMPLEXITY OF THE PROPER BIOASSAY INTERPRETATION. THE SPECIFICALLY DESIGNED EXPERIMENTS MAY HAVE THE OBJECTIVE TO EXPLORE PREDOMINANTLY THE INITIATING OR PROMOTING EFFECTS OF THE AGENT. SUCH PROTOCOLS SHOULD BE USED WHENEVER NECESSARY TO DIFFERENTIATE BETWEEN THESE TWO MECHANISMS OF ACTION. IN THE CAUCASIANS, THE "SPONTANEOUS" DEVELOPMENT OF THE PRIMARY HEPATOCELLULAR TUMORS IS RARE. THE MAJORITY OF THESE TUMORS ARE MALIGNANT AND RAPIDLY FATAL. ACCORDING TO SOME HUMAN PATHOLOGISTS, THE BENIGN VARIETY OF LIVER TUMORS IS RARE AND IT DOES NOT REPRESENT NECESSARILY A PREMALIGNANT STAGE IN TUMOR DEVELOPMENT. CARCINOMA OF THE LIVER MAY OCCUR IN INFANCY, ESPECIALLY IN MALES BEFORE THE AGE OF 2 YEARS. THIS SUGGESTS A GENETIC CAUSATION OR CARCINOGENIC EXPOSURE IN UTERO. ONE OF THE GEOGRAPHIC FACTORS WHICH SIGNIFICANTLY ENHANCES THE INCIDENCE OF HEPATOCELLULAR CARCINOMA IN HUMANS IS EXPOSURE TO AFLATOXIN B(1) WHICH IS APPARENTLY POTENTIATED BY CONCURRENT LIVER CIRRHOSIS. BECAUSE MANY MORE AGENTS HAVE BEEN FOUND TO BE HEPATOCARCINOGENIC IN MICE AND RATS THAN IN MEN, A QUESTION ARISES AS TO THE DIRECT RELEVANCE OF RODENT STUDIES TO HUMANS. A BALANCED ASSESSMENT OF THE CARCINOGENICITY OF THE AGENT COULD ONLY BE REACHED IN CONSIDERING BOTH THE PHARMACOKINETICS AND THE DEVELOPMENT OF MALIGNANT NEOPLASIA IN OTHER ORGANS. IN THE CASE OF POSITIVE CARCINOGENICITY ASSESSMENT, THE OUTCOME OF THE MUTAGENICITY BIOASSAYS CAN SUGGEST GENIC (GENOTOXIC) OR PARAGENIC (EPIGENETIC) MODE OF ACTION IN MAMMALIAN SYSTEMS. 1982 2 6361 56 THE ROLE OF INNATE IMMUNITY IN THE PATHOGENESIS OF PRENEOPLASIA IN DRUG-INDUCED CHRONIC HEPATITIS BASED ON A MOUSE MODEL. INNATE IMMUNITY FACTORS SUCH AS CONVERSION OF THE 26S PROTEASOME TO FORM THE IMMUNOPROTEASOME AND THE TOLL-LIKE RECEPTOR SIGNALING PATHWAYS ARE ACTIVATED IN CHRONIC HEPATITIS INDUCED BY THE CARCINOGENIC DRUG DDC. OVER TIME, PRENEOPLASTIC HEPATOCYTE PHENOTYPES APPEAR IN THE LIVER PARENCHYMA. THESE CHANGED HEPATOCYTES EXPAND IN NUMBER BECAUSE THEY HAVE A GROWTH ADVANTAGE OVER NORMAL HEPATOCYTES WHEN RESPONDING TO CHRONIC LIVER INJURY. THE CHANGED HEPATOCYTES CAN BE IDENTIFIED USING IMMUNOFLUORESCENT ANTIBODIES TO PRENEOPLASTIC CELLS E.G. FAT10/UBD, A2 MACROGLOBULIN, GLUTATHIONE TRANSPEPTIDASE, ALPHA FETOPROTEIN, GLYCIPAN 3, FAS, AND GAMMA GLUTAMYL TRANSPEPTIDASE. THE FORMATION OF THE PRENEOPLASTIC CELLS OCCURS CONCOMITANT WITH ACTIVATION OF THE TOLL-LIKE RECEPTOR SIGNALING PATHWAYS AND THE TRANSFORMATION OF THE 26S PROTEASOME TO FORM THE IMMUNOPROTEASOME. THIS TRANSFORMATION IS IN RESPONSE TO INTERFERON STIMULATING RESPONSE ELEMENT ON THE PROMOTER OF THE FAT10/UBD GENE. NFKAPPAB, ERK, P38 AND JNK ARE ALSO UP REGULATED. SPECIFIC INHIBITORS BLOCK THESE RESPONSES IN VITRO IN A MOUSE TUMOR CELL LINE EXPOSED TO INTERFERON GAMMA. MALLORY-DENK BODIES FORM IN THESE PRENEOPLASTIC CELLS, BECAUSE OF THE DEPLETION OF THE 26S PROTEASOME DUE TO FORMATION OF THE IMMUNOPROTEASOME. THUS, MDB FORMING CELLS ARE ALSO MARKERS OF THE PRENEOPLASTIC HEPATOCYTES. THE UBD POSITIVE PRENEOPLASTIC CELLS REGRESS WHEN THE LIVER INJURY INDUCED CHRONIC HEPATITIS SUBSIDES. WHEN THE DRUG DDC IS REFED TO MICE AND CHRONIC HEPATITIS IS ACTIVATED, THE PRENEOPLASTIC CELL POPULATION EXPANDS AND MALLORY-DENK BODIES RAPIDLY REFORM. THIS RESPONSE IS REMEMBERED BY THE PRENEOPLASTIC CELLS FOR AT LEAST FOUR MONTHS INDICATING THAT AN EPIGENETIC CELLULAR MEMORY HAS FORMED IN THE PRENEOPLASTIC CELLS. THIS PROLIFERATIVE RESPONSE IS PREVENTED BY FEEDING METHYL DONORS SUCH AS S-ADENOSYLMETHIONINE OR BETAINE. DRUG FEEDING REDUCES THE METHYLATION OF H(3) K4, 9, AND 27 AND THIS RESPONSE IS PREVENTED BY FEEDING THE METHYL DONORS. AFTER 8 TO 15MONTHS OF DRUG WITHDRAWAL IN MICE THE PRENEOPLASTIC LIVER CELLS PERSIST AS SINGLE OR SMALL CLUSTERS OF CELLS IN THE LIVER LOBULES. MULTIPLE LIVER TUMORS FORM, SOME OF WHICH ARE HEPATOCELLULAR CARCINOMAS. THE TUMORS IMMUNOSTAIN POSITIVELY FOR THE SAME PRENEOPLASTIC MARKERS AS THE PRENEOPLASTIC CELLS. SIMILAR CELLS ARE IDENTIFIED IN HUMAN CIRRHOSIS AND HEPATOCELLULAR CARCINOMA INDICATING THE RELEVANCE OF THE DRUG MODEL DESCRIBED HERE TO THE PRENEOPLASTIC CHANGES ASSOCIATED WITH HUMAN CHRONIC HEPATITIS AND HEPATOCELLULAR CARCINOMA. 2011 3 2792 38 FAT10 IS AN EPIGENETIC MARKER FOR LIVER PRENEOPLASIA IN A DRUG-PRIMED MOUSE MODEL OF TUMORIGENESIS. THERE IS CLINICAL EVIDENCE THAT CHRONIC LIVER DISEASES IN WHICH MDBS (MALLORY DENK BODIES) FORM PROGRESS TO HEPATOCELLULAR CARCINOMA. THE PRESENT STUDY PROVIDES EVIDENCE THAT LINKS MDB FORMATION INDUCED BY CHRONIC DRUG INJURY, WITH PRENEOPLASIA AND LATER TO THE FORMATION OF TUMORS, WHICH DEVELOP LONG AFTER DRUG WITHDRAWAL. EVIDENCE INDICATED THAT THIS LINK WAS DUE TO AN EPIGENETIC CELLULAR MEMORY INDUCED BY CHRONIC DRUG INGESTION. MICROARRAY ANALYSIS SHOWED THAT THE EXPRESSIONS OF MANY MARKERS OF PRENEOPLASIA (UBD, ALPHA FETOPROTEIN, KLF6 AND GLUTATHIONE-S-TRANSFERASE MU2) WERE INCREASED TOGETHER WHEN THE DRUG DDC WAS REFED. THESE CHANGES WERE SUPPRESSED BY S-ADENOSYLMETHIONINE FEEDING, INDICATING THAT THE DRUG WAS AFFECTING DNA AND HISTONES METHYLATION IN AN EPIGENETIC MANNER. THE LINK BETWEEN MDB FORMATION AND NEOPLASIA FORMATION WAS LIKELY DUE TO THE OVER EXPRESSION OF UBD (ALSO CALLED FAT10), WHICH IS UP REGULATED IN 90% OF HUMAN HEPATOCELLULAR CARCINOMAS. IMMUNOHISTOCHEMICAL STAINING OF DRUG-PRIMED MOUSE LIVERS SHOWED THAT FAT10 POSITIVE LIVER CELLS PERSISTED UP TO 4 MONTHS AFTER DRUG WITHDRAWAL AND THEY WERE STILL FOUND IN THE LIVERS OF MICE, 14 MONTHS AFTER DRUG WITHDRAWAL. THE REFEEDING OF DDC INCREASED THE PERCENT OF FAT10 HEPATOCYTES. 2008 4 5182 42 PREMALIGNANT LESIONS OF SQUAMOUS CELL CARCINOMA OF THE LUNG: THE MOLECULAR MAKE-UP AND FACTORS AFFECTING THEIR PROGRESSION. SQUAMOUS CELL CARCINOMA (SCC), ONE OF THE MOST COMMON FORMS OF LUNG CANCER, SHOWS ACCELERATED PROGRESSION AND AGGRESSIVE GROWTH AND USUALLY IS OBSERVED AT ADVANCED STAGES. SCC ORIGINATES FROM MORPHOLOGICAL CHANGES IN THE BRONCHIAL EPITHELIUM THAT OCCUR DURING CHRONIC INFLAMMATION: BASAL CELL HYPERPLASIA, SQUAMOUS METAPLASIA, AND DYSPLASIA I-III. HOWEVER, THE PROCESS IS NOT INEVITABLE; IT CAN BE STOPPED AT ANY STAGE, REMAIN IN THE STABLE STATE INDEFINITELY AND EITHER PROGRESS OR REGRESS. THE REASONS AND MECHANISMS OF DIFFERENT SCENARIOS OF THE EVOLUTION OF PREMALIGNANT LESIONS IN THE RESPIRATORY EPITHELIUM ARE NOT FULLY UNDERSTOOD. IN THIS REVIEW, WE SUMMARIZED THE LITERATURE DATA (INCLUDING OUR OWN DATA) REGARDING GENETIC, EPIGENETIC, TRANSCRIPTOMIC AND PROTEOMIC PROFILES OF THE PREMALIGNANT LESIONS AND HIGHLIGHTED FACTORS (ENVIRONMENTAL CAUSES, INFLAMMATION, AND GENE POLYMORPHISM) THAT MAY GOVERN THEIR PROGRESSION OR REGRESSION. IN CONCLUSION, WE REVIEWED STRATEGIES FOR LUNG CANCER PREVENTION AND PROPOSED NEW MODELS AND RESEARCH DIRECTIONS FOR STUDYING PREMALIGNANT LESIONS AND DEVELOPING NEW TOOLS TO PREDICT THE RISK OF THEIR MALIGNANT TRANSFORMATION. 2019 5 5057 47 PHENOBARBITAL MECHANISTIC DATA AND RISK ASSESSMENT: ENZYME INDUCTION, ENHANCED CELL PROLIFERATION, AND TUMOR PROMOTION. CHRONIC EXPOSURE TO HIGH DOSES OF PHENOBARBITAL (PB) CAUSES HEPATOCELLULAR ADENOMAS IN BOTH MICE AND RATS AND HEPATOCELLULAR CARCINOMAS IN SOME STRAINS OF MICE. LONG-TERM PB THERAPY HAS NOT BEEN FOUND TO CAUSE HUMAN TUMORS. PB IS NOT DNA REACTIVE, AND MOST GENOTOXICITY TESTS HAVE YIELDED NEGATIVE RESULTS. PB HAS BEEN EXTENSIVELY STUDIED AS AN EPIGENETIC, RODENT LIVER TUMOR PROMOTER. AT EXPOSURES CAUSING RODENT LIVER TUMORS, PB HAS MEASURABLE EFFECTS ON HEPATOCYTES: PB INHIBITS CELL-TO-CELL COMMUNICATION; PB INDUCES ENZYMES, INCLUDING P450 CYTOCHROMES; PB STIMULATES PROLIFERATION AND INHIBITS APOPTOSIS OF HEPATOCYTES IN NEOPLASTIC FOCI. THRESHOLD EXPOSURES FOR SOME OF THESE ENDPOINTS COINCIDE WITH THE THRESHOLD EXPOSURE FOR TUMORIGENESIS. 1996 6 835 56 CHEMICAL CARCINOGEN MECHANISMS OF ACTION AND IMPLICATIONS FOR TESTING METHODOLOGY. CHEMICAL CARCINOGENS ARE OF TWO DISTINCT TYPES, DNA-REACTIVE AND EPIGENETIC. TESTING METHODOLOGY CAN BE DIRECTED TOWARD DETECTING EFFECTS OF BOTH TYPES OF CARCINOGEN. CARCINOGENS OF THE DNA-REACTIVE TYPE ARE DEFINED BY THE FORMATION OF COVALENTLY BOUND DNA ADDUCTS. THESE CHEMICALS HAVE STRUCTURES THAT YIELD ELECTROPHILIC REACTANTS EITHER DIRECTLY OR AFTER BIOACTIVATION. THESE AGENTS CAUSE GENOMIC ALTERATION IN THE STRUCTURE OR FUNCTION OF DNA IN THE TARGET CELL. IN ADDITION, THESE COMPOUNDS CAN EXERT OTHER CELLULAR AND TISSUE EPIGENETIC EFFECTS, SUCH AS CELL PROLIFERATION AND GROWTH PROMOTION. CARCINOGENS OF THE EPIGENETIC (PARAGENETIC) TYPE, IN CONTRAST, DO NOT REACT WITH DNA, BUT RATHER DISPLAY CELLULAR EFFECTS SUCH AS NEOPLASM GROWTH PROMOTION, CYTOTOXICITY, INHIBITION OF TISSUE GROWTH REGULATION, PEROXISOME PROLIFERATION, ENDOCRINE MODIFICATION, IMMUNOSUPPRESSION AND/OR SUSTAINED TISSUE ISCHEMIA THAT CAN BE THE BASIS FOR INCREASES IN NEOPLASIA. THEIR CHEMICAL STRUCTURE IS SUCH THAT THEY DO NOT GIVE RISE TO A REACTIVE ELECTROPHILE. THE TESTING METHODOLOGIES TO IDENTIFY EITHER TYPE FOLLOW A DECISION POINT APPROACH DESIGNED TO IDENTIFY POTENTIAL CARCINOGENICITY AND YIELD MECHANISTIC INFORMATION ON THE PRODUCTION OF EFFECTS THAT UNDERLIE CARCINOGENICITY. IT HAS 5 STAGES FOCUSING ON THE CHEMICAL STRUCTURE, DNA-REACTIVITY, EPIGENETIC EFFECTS, LIMITED BIOASSAYS AND FINALLY THE APPLICATION OF THE ACCELERATED BIOASSAY (ABA). ABA REQUIRES 40 WEEKS AND APPLIES THE USE OF SENSITIVE MARKERS FOR INDUCTION OF NEOPLASIA IN COMPARISON TO POSITIVE CONTROL COMPOUNDS FOR IMPORTANT ORGANS IN HUMAN CARCINOGENESIS. IT ENABLES DATA ACQUISITION OF THE ENTIRE CARCINOGENIC PROCESS DIRECTED TOWARD DEVELOPING MECHANISTIC INFORMATION. THE ABA HAS THE POTENTIAL TO REPLACE THE CHRONIC BIOASSAY IN RODENTS IN SOME CIRCUMSTANCES AND CAN SERVE AS AN ALTERNATIVE TO A CHRONIC BIOASSAY IN A SECOND SPECIES. 1996 7 6310 42 THE REGULATION OF NON-CODING RNA EXPRESSION IN THE LIVER OF MICE FED DDC. MALLORY-DENK BODIES (MDBS) ARE FOUND IN THE LIVER OF PATIENTS WITH ALCOHOLIC AND CHRONIC NONALCOHOLIC LIVER DISEASE, AND HEPATOCELLULAR CARCINOMA (HCC). DIETHYL 1,4-DIHYDRO-2,4,6,-TRIMETHYL-3,5-PYRIDINEDICARBOXYLATE (DDC) IS USED AS A MODEL TO INDUCE THE FORMATION OF MDBS IN MOUSE LIVER. PREVIOUS STUDIES IN THIS LABORATORY SHOWED THAT DDC INDUCED EPIGENETIC MODIFICATIONS IN DNA AND HISTONES. THE COMBINATION OF THESE MODIFICATIONS CHANGES THE PHENOTYPE OF THE MDB FORMING HEPATOCYTES, AS INDICATED BY THE MARKER FAT10. THESE EPIGENETIC MODIFICATIONS ARE PARTIALLY PREVENTED BY ADDING TO THE DIET S-ADENOSYLMETHIONINE (SAME) OR BETAINE, BOTH METHYL DONORS. THE EXPRESSION OF THREE IMPRINTED NCRNA GENES WAS FOUND TO CHANGE IN MDB FORMING HEPATOCYTES, WHICH IS THE SUBJECT OF THIS REPORT. NCRNA EXPRESSION WAS QUANTITATED BY REAL-TIME PCR AND RNA FISH IN LIVER SECTIONS. MICROARRAY ANALYSIS SHOWED THAT THE EXPRESSION OF THREE NCRNAS WAS REGULATED BY DDC: UP REGULATION OF H19, ANTISENSE IGF2R (AIR), AND DOWN REGULATION OF GTL2 (ALSO CALLED MEG3). S-ADENOSYLMETHIONINE (SAME) FEEDING PREVENTED THESE CHANGES. BETAINE, ANOTHER METHYL GROUP DONOR, PREVENTED ONLY H19 AND AIR UP REGULATION INDUCED BY DDC, ON MICROARRAYS. THE RESULTS OF THE SAME AND BETAINE GROUPS WERE CONFIRMED BY REAL-TIME PCR, EXCEPT FOR AIR EXPRESSION. AFTER 1 MONTH OF DRUG WITHDRAWAL, THE EXPRESSION OF THE THREE NCRNAS TENDED TOWARD CONTROL LEVELS OF EXPRESSION. LIVER TUMORS THAT DEVELOPED ALSO SHOWED UP REGULATION OF H19 AND AIR. THE RNA FISH APPROACH SHOWED THAT THE MDB FORMING CELLS' PHENOTYPE CHANGED THE LEVEL OF EXPRESSION OF AIR, H19 AND GTL2, COMPARED TO THE SURROUNDING CELLS. FURTHERMORE, OVER EXPRESSION OF H19 AND AIR WAS DEMONSTRATED IN TUMORS FORMED IN MICE WITHDRAWN FOR 9 MONTHS. THE DYSREGULATION OF NCRNA IN MDB FORMING LIVER CELLS HAS BEEN OBSERVED FOR THE FIRST TIME IN DRUG-PRIMED MICE ASSOCIATED WITH LIVER PRENEOPLASTIC FOCI AND TUMORS. 2009 8 5282 49 PROMOTION OF HEPATOCARCINOGENESIS IN HUMANS AND ANIMAL MODELS. RISK ASSESSMENT BASED ON RODENT CARCINOGENICITY DATA DEPENDS ON THE ASSUMPTION OF SIMILARITY BETWEEN RODENTS AND HUMANS. WHILE THIS ASSUMPTION IS CONCEIVABLE IN THE CASE OF GENOTOXIC INITIATING CARCINOGENS, CONSIDERABLE SPECIES DIFFERENCES HAVE BEEN OBSERVED WITH NONGENOTOXIC TUMOR PROMOTERS. THIS HETEROGENEOUS GROUP OF AGENTS INCREASES THE PROBABILITY OF CANCER BY STIMULATING SELECTION AND CLONAL EXPANSION OF CELLS TRANSFORMED DURING TUMOR INITIATION. SINCE TUMOR PROMOTERS DIFFERENTIALLY AFFECT NORMAL TISSUE AND PRENEOPLASTIC CELL CLONES, THEIR ACTION CANNOT BE DISCUSSED WITHOUT KNOWLEDGE OF PERSISTENT GENOMIC AND EPIGENETIC ALTERATIONS OCCURRING DURING INITIATION AND FORMATION OF PRENEOPLASTIC CELLS. CHEMICAL CARCINOGENESIS, AND IN PARTICULAR, TUMOR PROMOTION, IS KNOWN TO BE TISSUE SPECIFIC. WE FOCUS ON HEPATOCARCINOGENESIS IN HUMANS AND IN ANIMAL MODELS AND EMPHASIZE TWO DIFFERENT MODES OF ACTION: (1) CHRONIC CYTOTOXICITY LEADING TO PROMOTION OF LIVER CARCINOGENESIS IN BOTH HUMANS AND ANIMAL MODELS; (2) SUSTAINED ACTIVATION OF ORPHAN RECEPTORS SUCH AS CAR, PPARALPHA AND AH RECEPTOR LEADING TO PROMOTION OF RODENT BUT PROBABLY NOT HUMAN HEPATOCARCINOGENESIS. FURTHER STUDIES ON THE DIFFERENT MODES OF ACTION MAY HELP TO AVOID OVERESTIMATION OF THE RISK OF LIVER TUMOR PROMOTION. 2008 9 567 47 BASIC PROPERTIES AND MOLECULAR MECHANISMS OF EXOGENOUS CHEMICAL CARCINOGENS. EXOGENOUS CHEMICAL CARCINOGENESIS IS AN EXTREMELY COMPLEX MULTIFACTORIAL PROCESS DURING WHICH GENE-ENVIRONMENT INTERACTIONS INVOLVING CHRONIC EXPOSURE TO EXOGENOUS CHEMICAL CARCINOGENS (ECCS) AND POLYMORPHISMS OF CANCER SUSCEPTIBILITY GENES ADD FURTHER COMPLEXITY. WE DESCRIBE THE PROPERTIES AND MOLECULAR MECHANISMS OF ECCS THAT CONTRIBUTE TO INDUCE AND GENERATE CANCER. A BASIC AND SPECIFIC PROPERTY OF MANY LIPOPHILIC ORGANIC ECCS INCLUDING POLYCYCLIC AROMATIC HYDROCARBONS AND POLYHALOGENATED AROMATIC HYDROCARBONS IS THEIR ABILITY TO BIOACCUMULATE IN THE ADIPOSE TISSUE FROM WHERE THEY MAY BE RELEASED IN THE BLOOD CIRCULATION AND TARGET PERIPHERAL TISSUES FOR CARCINOGENESIS. MANY ORGANIC ECCS ARE PROCARCINOGENS AND CONSEQUENTLY NEED TO BE ACTIVATED BY THE CYTOCHROME P450 (CYP) SYSTEM AND/OR OTHER ENZYMES BEFORE THEY CAN ADDUCT DNA AND PROTEINS. BECAUSE THEY CONTRIBUTE NOT ONLY TO THE COCARCINOGENIC AND PROMOTING EFFECTS OF MANY AROMATIC POLLUTANTS BUT ALSO TO THEIR MUTAGENIC EFFECTS, THE ARYL HYDROCARBON RECEPTOR-ACTIVATING AND THE INDUCIBLE CYP SYSTEMS ARE CENTRAL TO EXOGENOUS CHEMICAL CARCINOGENESIS. ANOTHER BASIC PROPERTY OF ECCS IS THEIR ABILITY TO INDUCE STABLE AND BULKY DNA ADDUCTS THAT CANNOT BE SIMPLY REPAIRED BY THE DIFFERENT REPAIR SYSTEMS. IN ADDITION, FOLLOWING ECC EXPOSURE, MUTAGENESIS MAY ALSO BE CAUSED INDIRECTLY BY FREE-RADICAL PRODUCTION AND BY EPIGENETIC ALTERATIONS. AS A RESULT OF COMPLEX MOLECULAR INTERPLAYS, DIRECT AND/OR INDIRECT MUTAGENESIS MAY ESPECIALLY ACCOUNT FOR THE CARCINOGENIC EFFECTS OF MANY EXOGENOUS METALS AND METALLOIDS. BECAUSE OF THESE MOLECULAR PROPERTIES AND ACTION MECHANISMS, WE CONCLUDE THAT ECCS COULD BE MAJOR CONTRIBUTORS TO HUMAN CANCER, WITH OBVIOUSLY GREAT PUBLIC HEALTH CONSEQUENCES. 2010 10 3271 45 HEPATOCELLULAR CARCINOMA RISK AFTER VIRAL RESPONSE IN HEPATITIS C VIRUS-ADVANCED FIBROSIS: WHO TO SCREEN AND FOR HOW LONG? HEPATITIS C VIRUS (HCV) CHRONIC INFECTION IS ASSOCIATED WITH FIBROSIS PROGRESSION, END-STAGE LIVER COMPLICATIONS AND HCC. NOT SURPRISINGLY, HCV INFECTION IS A LEADING CAUSE OF LIVER-RELATED MORBIDITY AND MORTALITY WORLDWIDE. AFTER SUSTAINED VIROLOGICAL RESPONSE (SVR), THE RISK OF DEVELOPING HEPATOCELLULAR CARCINOMA IS NOT COMPLETELY ELIMINATED IN PATIENTS WITH ESTABLISHED CIRRHOSIS OR WITH ADVANCED FIBROSIS. THEREFORE, LIFELONG SURVEILLANCE IS CURRENTLY RECOMMENDED. THIS STRATEGY IS LIKELY NOT UNIVERSALLY COST-EFFECTIVE AND HARMLESS, CONSIDERING THAT NOT ALL PATIENTS WITH ADVANCED FIBROSIS HAVE THE SAME RISK OF DEVELOPING HCC. FACTORS RELATED TO THE SEVERITY OF LIVER DISEASE AND ITS POTENTIAL TO IMPROVE AFTER SVR, THE MOLECULAR AND EPIGENETIC CHANGES THAT OCCUR DURING INFECTION AND OTHER ASSOCIATED COMORBIDITIES MIGHT ACCOUNT FOR DIFFERENT RISK LEVELS AND ARE LIKELY ESSENTIAL FOR IDENTIFYING PATIENTS WHO WOULD BENEFIT FROM SCREENING PROGRAMS AFTER SVR. EFFORTS TO DEVELOP PREDICTIVE MODELS AND RISK CALCULATORS, BIOMARKERS AND GENETIC PANELS AND EVEN DEEP LEARNING MODELS TO ESTIMATE THE INDIVIDUAL RISK OF HCC HAVE BEEN MADE IN THE DIRECT-ACTING ANTIVIRAL AGENTS ERA, WHEN THOUSANDS OF PATIENTS WITH ADVANCED FIBROSIS AND CIRRHOSIS HAVE REACHED SVR. THESE TOOLS COULD HELP TO IDENTIFY PATIENTS WITH VERY LOW HCC RISK IN WHOM SURVEILLANCE MIGHT NOT BE JUSTIFIED. IN THIS REVIEW, FACTORS AFFECTING THE PROBABILITY OF HCC DEVELOPMENT AFTER SVR, THE BENEFITS AND RISKS OF SURVEILLANCE, SUGGESTED STRATEGIES TO ESTIMATE INDIVIDUALIZED HCC RISK AND THE CURRENT EVIDENCE TO RECOMMEND LIFELONG SURVEILLANCE ARE DISCUSSED. 2021 11 6486 41 TP53 AND LIVER CARCINOGENESIS. PRIMARY HEPATOCELLULAR CARCINOMA (HCC) IS ONE OF THE MOST COMMON MALIGNANCIES AND HAS THE FOURTH HIGHEST MORTALITY RATE WORLDWIDE. THE MAJOR RISK FACTORS, INCLUDING CHRONIC INFECTIONS WITH THE HEPATITIS B OR C VIRUS, ARE EXPOSURE TO DIETARY AFLATOXIN B1(AFB1), VINYL CHLORIDE, OR ALCOHOL CONSUMPTION. SOUTHERN CHINA AND SUB-SAHARAN AFRICA HAVE THE HIGHEST DIETARY AFB1 EXPOSURE, MAKING IT AND HEPATITIS B VIRUS (HBV) THE MAJOR CAUSES OF CANCER MORTALITY IN THESE GEOGRAPHIC AREAS. RECENT STUDIES HAVE DISCOVERED GENETIC AND EPIGENETIC CHANGES INVOLVED IN THE MOLECULAR PATHOGENESIS OF HCC, INCLUDING SOMATIC MUTATIONS IN THE P53 TUMOR SUPPRESSOR GENE (TP53). AFB1 INDUCES TYPICAL G:C TO T:A TRANSVERSIONS AT THE THIRD BASE IN CODON 249 OF P53. CHRONIC ACTIVE HEPATITIS B AND C (HCV) INFECTION, AND FURTHER INFLAMMATORY AND OXYRADICAL DISORDERS INCLUDING WILSON DISEASE (WD) OR HEMOCHROMATOSIS, GENERATE REACTIVE OXYGEN/NITROGEN SPECIES THAT CAN DAMAGE DNA AND MUTATE THE P53 GENE. THE X GENE OF HBV (HBX) IS THE MOST COMMON OPEN READING FRAME INTEGRATED INTO THE HOST GENOME IN HCC. THE INTEGRATED HBX IS FREQUENTLY MUTATED AND HAS A DIMINISHED ABILITY TO FUNCTION AS A TRANSCRIPTIONAL COTRANSACTIVATOR AND TO ACTIVATE THE NF-KAPPA B PATHWAY. HOWEVER, THE MUTANT HBX PROTEINS STILL RETAIN THEIR ABILITY TO BIND TO AND ABROGATE P53-MEDIATED APOPTOSIS. IN SUMMARY, BOTH VIRUSES AND CHEMICALS ARE IMPLICATED IN THE ETIOLOGY AND MOLECULAR PATHOGENESIS OF HCC. THE RESULTANT MOLECULAR CHANGES IN THE RAS AND WNT SIGNAL-TRANSDUCTION PATHWAYS, AND THE P53 AND RB TUMOR SUPPRESSOR PATHWAYS SIGNIFICANTLY CONTRIBUTE TO LIVER CARCINOGENESIS 2003 12 5493 26 REVIEW OF IN VITRO TEST SYSTEMS USING DNA DAMAGE AND REPAIR FOR SCREENING OF CHEMICAL CARCINOGENS. CHEMICAL CARCINOGENS ARE MECHANISTICALLY CLASSIFIED AS GENOTOXIC WHICH INTERACT DIRECTLY WITH DNA, AND EPIGENETIC WHICH CAUSE CHRONIC TISSUE INJURY, HORMONAL IMBALANCE, AND PROMOTIONAL EFFECTS. THIS REVIEW EVALUATES IN VITRO TESTS FOR THEIR CONTRIBUTION TO A BATTERY FOR IDENTIFYING GENOTOXIC CHEMICAL CARCINOGENS. IN ADDITION TO BACTERIAL MUTAGENIC ASSAYS, NONSPECIFIC DNA DAMAGE/REPAIR TESTS ARE RECOMMENDED FOR SCREENING CHEMICALS, IN PARTICULAR THE HEPATOCYTE PRIMARY CULTURE/DNA REPAIR TEST. 1979 13 4134 58 MECHANISMS OF HUMAN HEPATOCARCINOGENESIS. THE MAJOR RISK FACTORS AND ETIOLOGICAL AGENTS RESPONSIBLE FOR DEVELOPMENT OF HEPATOCELLULAR CARCINOMA IN HUMANS HAVE BEEN IDENTIFIED AND CHARACTERIZED. AMONG THESE ARE CHRONIC INFECTION WITH HEPATITIS B VIRUS OR HEPATITIS C VIRUS, EXPOSURE TO AFLATOXIN B1, AND CIRRHOSIS OF ANY ETIOLOGY (INCLUDING ALCOHOLIC CIRRHOSIS AND CIRRHOSIS ASSOCIATED WITH GENETIC LIVER DISEASES). BOTH CHRONIC HEPATITIS AND CIRRHOSIS REPRESENT MAJOR PRENEOPLASTIC CONDITIONS OF THE LIVER AS THE MAJORITY OF HEPATOCELLULAR CARCINOMAS ARISE IN THESE PATHOLOGICAL SETTINGS. HEPATOCARCINOGENESIS REPRESENTS A LINEAR AND PROGRESSIVE PROCESS IN WHICH SUCCESSIVELY MORE ABERRANT MONOCLONAL POPULATIONS OF HEPATOCYTES EVOLVE. REGENERATIVE HEPATOCYTES IN FOCAL LESIONS IN THE INFLAMED LIVER (CHRONIC HEPATITIS OR CIRRHOSIS) GIVE RISE TO HYPERPLASTIC HEPATOCYTE NODULES, AND THESE PROGRESS TO DYSPLASTIC NODULES, WHICH ARE THOUGHT TO BE THE DIRECT PRECURSOR OF HEPATOCELLULAR CARCINOMA. IN MOST CASES, THE NEOPLASTIC TRANSFORMATION OF HEPATOCYTES RESULTS FROM ACCUMULATION OF GENETIC DAMAGE DURING THE REPETITIVE CELLULAR PROLIFERATION THAT OCCURS IN THE INJURED LIVER IN RESPONSE TO PARACRINE GROWTH FACTOR AND CYTOKINE STIMULATION. HEPATOCELLULAR CARCINOMAS EXHIBIT NUMEROUS GENETIC ABNORMALITIES (INCLUDING CHROMOSOMAL DELETIONS, REARRANGEMENTS, ANEUPLOIDY, GENE AMPLIFICATIONS, AND MUTATIONS), AS WELL AS EPIGENETIC ALTERATIONS (INCLUDING MODULATION OF DNA METHYLATION). THESE GENETIC AND EPIGENETIC ALTERATIONS COMBINE TO ACTIVATE POSITIVE MEDIATORS OF CELLULAR PROLIFERATION (INCLUDING CELLULAR PROTO-ONCOGENES AND THEIR MITOGENIC SIGNALING PATHWAYS) AND INACTIVATE NEGATIVE MEDIATORS OF CELLULAR PROLIFERATION (INCLUDING TUMOR SUPPRESSOR GENES), RESULTING IN CELLS WITH AUTONOMOUS GROWTH POTENTIAL. HOWEVER, HEPATOCELLULAR CARCINOMAS EXHIBIT A HIGH DEGREE OF GENETIC HETEROGENEITY, SUGGESTING THAT MULTIPLE MOLECULAR PATHWAYS MAY BE INVOLVED IN THE GENESIS OF SUBSETS OF HEPATOCELLULAR NEOPLASMS. CONTINUED INVESTIGATION OF THE MECHANISMS OF HEPATOCARCINOGENESIS WILL REFINE OUR CURRENT UNDERSTANDING OF THE MOLECULAR AND CELLULAR BASIS FOR NEOPLASTIC TRANSFORMATION IN LIVER, ENABLING THE DEVELOPMENT OF EFFECTIVE STRATEGIES FOR PREVENTION AND/OR MORE EFFECTIVE TREATMENT OF HEPATOCELLULAR CARCINOMA. 2003 14 3803 60 INTESTINAL METAPLASIA OF THE STOMACH. A STATUS REPORT. INTESTINAL METAPLASIA IN THE STOMACH INCREASES THE RISK OF GASTRIC CANCER, AND THE INCREASED RISK IS PROPORTIONAL TO THE EXTENT OF THE METAPLASIA. THIS RISK COULD BE GENERATED BY ONE OR MORE MECHANISMS: (1) THE METAPLASTIC TISSUE IS AN EARLY STEP IN A MULTISTEP INDUCTION PROCESS; (2) THE METAPLASTIC TISSUE IS AN EPIGENETIC CHANGE THAT RAISES THE PH OF GASTRIC JUICE BY REPLACING OXYNTIC MUCOSA, FAVORING THE GROWTH OF A BACTERIA CAPABLE OF GENERATING ENDOGENOUS MUTAGENS; AND/OR (3) THE METAPLASIA IS ONLY A MARKER FOR CHRONIC GASTRITIS DUE TO H. PYLORI INFECTION OR PERNICIOUS ANEMIA. WITH THE LAST MECHANISM, THE INFLAMMATORY RESPONSE FAVORS INTRAMURAL MUTAGENESIS THAT MIGHT RESULT IN METAPLASIA OR NEOPLASIA AS INDEPENDENT EVENTS. FINDING GENE REARRANGEMENTS COMMON TO BOTH METAPLASTIC AND NEOPLASTIC TISSUE MAY ESTABLISH A DIRECT LINK BETWEEN THEM, BUT TOO FEW HAVE BEEN IDENTIFIED TO ACCOUNT FOR THE LARGE NUMBER OF STOMACH CANCERS THAT DEVELOP IN HIGH RISK POPULATIONS. HISTOCHEMICAL AND IMMUNOCHEMICAL STAINS THAT IDENTIFY ENZYMES OR MUCOSUBSTANCES MAY SUGGEST THAT METAPLASTIC EPITHELIAL CELLS RESEMBLE SMALL OR LARGE INTESTINAL CELLS, BUT THEY ARE DISTINCTLY DIFFERENT FROM BOTH. MOREOVER, THESE STAINS DO NOT INDICATE WHETHER A GIVEN CYTOLOGIC CHANGE IS GENETIC OR EPIGENETIC; THEREFORE, THEY CANNOT BE USED TO DEFINE THE RELATIONSHIP BETWEEN METAPLASIA AND NEOPLASIA. IT IS UNNECESSARY FOR PRACTICING PHYSICIANS TO AWAIT RESOLUTION OF THIS QUESTION. IT CAN BE ASSUMED THAT ANY PERSON WITH EXTENSIVE METAPLASIA IS AT HIGH RISK FOR GASTRIC CANCER AND SHOULD BE SUBJECT TO PERIODIC SCREENING. THE EXTENT OF THE METAPLASTIC PROCESS IS PROBABLY MORE IMPORTANT THAN THE METAPLASTIC SUBTYPE. 1994 15 837 81 CHEMICALLY INDUCED RENAL TUBULE TUMORS IN THE LABORATORY RAT AND MOUSE: REVIEW OF THE NCI/NTP DATABASE AND CATEGORIZATION OF RENAL CARCINOGENS BASED ON MECHANISTIC INFORMATION. THE INCIDENCE OF RENAL TUBULE CARCINOGENESIS IN MALE AND FEMALE RATS OR MICE WITH 69 CHEMICALS FROM THE 513 BIOASSAYS CONDUCTED TO DATE BY THE NCI/NTP HAS BEEN COLLATED, THE CHEMICALS CATEGORIZED, AND THE RELATIONSHIP BETWEEN CARCINOGENESIS AND RENAL TUBULE HYPERPLASIA AND EXACERBATION OF THE SPONTANEOUS, AGE-RELATED RODENT DISEASE CHRONIC PROGRESSIVE NEPHROPATHY (CPN) EXAMINED. WHERE INFORMATION ON MECHANISM OR MODE OF ACTION EXISTS, THE CHEMICALS HAVE BEEN CATEGORIZED BASED ON THEIR ABILITY TO DIRECTLY OR INDIRECTLY INTERACT WITH RENAL DNA, OR ON THEIR ACTIVITY VIA EPIGENETIC PATHWAYS INVOLVING EITHER DIRECT OR INDIRECT CYTOTOXICITY WITH REGENERATIVE HYPERPLASIA, OR EXACERBATION OF CPN. NINE CHEMICALS WERE IDENTIFIED AS DIRECTLY INTERACTING WITH DNA, WITH SIX OF THESE PRODUCING RENAL TUBULE TUMORS AT HIGH INCIDENCE IN RATS OF BOTH SEXES, AND IN SOME CASES ALSO IN MICE. OCHRATOXIN A WAS THE MOST POTENT COMPOUND IN THIS GROUP, PRODUCING A HIGH TUMOR INCIDENCE AT VERY LOW DOSES, OFTEN WITH METASTASIS. THREE CHEMICALS WERE DISCUSSED IN THE CONTEXT OF INDIRECT DNA DAMAGE MEDIATED BY AN OXIDATIVE FREE RADICAL MECHANISM, ONE OF THESE BEING FROM THE NTP DATABASE. A THIRD CATEGORY INCLUDED FOUR CHEMICALS THAT HAD THE POTENTIAL TO CAUSE DNA DAMAGE FOLLOWING CONJUGATION WITH GLUTATHIONE AND SUBSEQUENT ENZYMATIC ACTIVATION TO A REACTIVE SPECIES, USUALLY A THIOL-CONTAINING ENTITY. TWO CHEMICALS WERE ALLOCATED INTO THE CATEGORY INVOLVING A DIRECT CYTOTOXIC ACTION ON THE RENAL TUBULE FOLLOWED BY SUSTAINED COMPENSATORY CELL PROLIFERATION, WHILE NINE WERE INCLUDED IN A GROUP WHERE THE CELL LOSS AND SUSTAINED INCREASE IN RENAL TUBULE CELL TURNOVER WERE DEPENDENT ON LYSOSOMAL ACCUMULATION OF THE MALE RAT-SPECIFIC PROTEIN, ALPHA2MU-GLOBULIN. IN A SIXTH CATEGORY, MORPHOLOGIC EVIDENCE ON TWO CHEMICALS INDICATED THAT THE RENAL TUMORS WERE A CONSEQUENCE OF EXACERBATED CPN. FOR THE REMAINING CHEMICALS, THERE WERE NO PERTINENT DATA ENABLING ASSIGNMENT TO A MECHANISTIC CATEGORY. ACCORDINGLY, THESE CHEMICALS, ACTING THROUGH AN AS YET UNKNOWN MECHANISM, WERE GROUPED AS EITHER BEING ASSOCIATED WITH AN ENHANCEMENT OF CPN (CATEGORY 7, 16 CHEMICALS), OR NOT ASSOCIATED WITH ENHANCED CPN (CATEGORY 8, 4 CHEMICALS). A NINTH CATEGORY DEALT WITH 11 CHEMICALS THAT WERE REGARDED AS PRODUCING INCREASES IN RENAL TUBULE TUMORS THAT DID NOT REACH STATISTICAL SIGNIFICANCE. A 10TH CATEGORY DISCUSSED 6 CHEMICALS THAT INDUCED RENAL TUMORS IN MICE BUT NOT IN RATS, PLUS 8 CHEMICALS THAT PRODUCED A LOW INCIDENCE OF RENAL TUBULE TUMORS IN MICE THAT DID NOT REACH STATISTICAL SIGNIFICANCE. AS MORE MECHANISTIC DATA ARE GENERATED, SOME CHEMICALS WILL INEVITABLY BE PLACED IN DIFFERENT GROUPS, PARTICULARLY THOSE FROM CATEGORIES 7 AND 8. A LARGE NUMBER OF CHEMICALS IN THE SERIES EXACERBATED CPN, BUT THOSE IN CATEGORY 7 ESPECIALLY MAY BE CANDIDATES FOR INCLUSION IN CATEGORY 6 WHEN FURTHER INFORMATION IS GLEANED FROM THE RELEVANT NTP STUDIES. ALSO, NEW DATA ON SPECIFIC CHEMICALS WILL PROBABLY EXPAND CATEGORY 5 AS CYTOTOXICITY AND CELL REGENERATION ARE IDENTIFIED AS OBLIGATORY STEPS IN RENAL CARCINOGENESIS IN MORE CASES. ADDITIONAL CONFIRMATORY OUTCOMES ARISING FROM THIS REVIEW ARE THAT METASTASES FROM RENAL TUBULE TUMORS, WHILE ENCOUNTERED WITH CHEMICALS CAUSING DNA DAMAGE, ARE RARE WITH THOSE ACTING THROUGH AN EPIGENETIC PATHWAY, WITH THE EXCEPTION BEING FUMONISIN B1; THAT MALE RATS AND MICE ARE GENERALLY MORE SUSCEPTIBLE THAN FEMALE RATS AND MICE TO CHEMICAL INDUCTION OF RENAL TUBULE TUMORS; AND THAT A BACKGROUND OF ATYPICAL TUBULE HYPERPLASIA IS A USEFUL INDICATOR REFLECTING A CHEMICALLY ASSOCIATED RENAL TUBULE TUMOR RESPONSE. WITH RESPECT TO RENAL TUBULE TUMORS AND HUMAN RISK ASSESSMENT, CHEMICALS IN CATEGORIES 1 AND 2, AND POSSIBLY 3, WOULD CURRENTLY BE JUDGED BY LINEAR DEFAULT METHODS; CHEMICALS IN CATEGORY 4 (AND PROBABLY SOME IN CATEGORY 3) AS EXHIBITING A THRESHOLD OF ACTIVITY WARRANTING THE BENCHMARK APPROACH; AND THOSE IN CATEGORIES 5 AND 6 AS REPRESENTING MECHANISMS THAT HAVE NO RELEVANCE FOR EXTRAPOLATION TO HUMANS. 2004 16 6406 41 THE SEARCH FOR RELIABLE BIOMARKERS OF DISEASE IN MULTIPLE CHEMICAL SENSITIVITY AND OTHER ENVIRONMENTAL INTOLERANCES. WHILST FACING A WORLDWIDE FAST INCREASE OF FOOD AND ENVIRONMENTAL ALLERGIES, THE MEDICAL COMMUNITY IS ALSO CONFRONTED WITH ANOTHER INHOMOGENEOUS GROUP OF ENVIRONMENT-ASSOCIATED DISABLING CONDITIONS, INCLUDING MULTIPLE CHEMICAL SENSITIVITY (MCS), FIBROMYALGIA, CHRONIC FATIGUE SYNDROME, ELECTRIC HYPERSENSITIVITY, AMALGAM DISEASE AND OTHERS. THESE SHARE THE FEATURES OF POLY-SYMPTOMATIC MULTI-ORGAN CUTANEOUS AND SYSTEMIC MANIFESTATIONS, WITH POSTULATED INHERITED/ACQUIRED IMPAIRED METABOLISM OF CHEMICAL/PHYSICAL/NUTRITIONAL XENOBIOTICS, TRIGGERING ADVERSE REACTIONS AT EXPOSURE LEVELS FAR BELOW TOXICOLOGICALLY-RELEVANT VALUES, OFTEN IN THE ABSENCE OF CLEAR-CUT ALLERGOLOGIC AND/OR IMMUNOLOGIC INVOLVEMENT. DUE TO THE LACK OF PROVEN PATHOGENIC MECHANISMS GENERATING MEASURABLE DISEASE BIOMARKERS, THESE ENVIRONMENTAL HYPERSENSITIVITIES ARE GENERALLY IGNORED BY SANITARY AND SOCIAL SYSTEMS, AS PSYCHOGENIC OR "MEDICALLY UNEXPLAINED SYMPTOMS". THE UNCONTROLLED APPLICATION OF DIAGNOSTIC AND TREATMENT PROTOCOLS NOT CORRESPONDING TO ACCEPTABLE LEVELS OF VALIDATION, SAFETY, AND CLINICAL EFFICACY, TO A STEADILY INCREASING NUMBER OF PATIENTS DEMANDING ASSISTANCE, OCCURS IN MANY COUNTRIES IN THE ABSENCE OF EVIDENCE-BASED GUIDELINES. HERE WE REVISE AVAILABLE INFORMATION SUPPORTING THE ORGANIC NATURE OF THESE CLINICAL CONDITIONS. FOLLOWING INTENSE RESEARCH ON GENE POLYMORPHISMS OF PHASE I/II DETOXIFICATION ENZYME GENES, SO FAR STATISTICALLY INCONCLUSIVE, EPIGENETIC AND METABOLIC FACTORS ARE UNDER INVESTIGATION, IN PARTICULAR FREE RADICAL/ANTIOXIDANT HOMEOSTASIS DISTURBANCES. THE FINDING OF RELEVANT ALTERATIONS OF CATALASE, GLUTATHIONE-TRANSFERASE AND PEROXIDASE DETOXIFYING ACTIVITIES SIGNIFICANTLY CORRELATING WITH CLINICAL MANIFESTATIONS OF MCS, HAS RECENTLY REGISTERED SOME PROGRESS TOWARDS THE IDENTIFICATION OF RELIABLE BIOMARKERS OF DISEASE ONSET, PROGRESSION, AND TREATMENT OUTCOMES. 2011 17 4769 42 NUCLEAR MORPHOMETRY, NUCLEOMICS AND PROSTATE CANCER PROGRESSION. PROSTATE CANCER (PCA) RESULTS FROM A MULTISTEP PROCESS. THIS PROCESS INCLUDES INITIATION, WHICH OCCURS THROUGH VARIOUS AGING EVENTS AND MULTIPLE INSULTS (SUCH AS CHRONIC INFECTION, INFLAMMATION AND GENETIC INSTABILITY THROUGH REACTIVE OXYGEN SPECIES CAUSING DNA DOUBLE-STRAND BREAKS), FOLLOWED BY A MULTISTEP PROCESS OF PROGRESSION. THESE STEPS INCLUDE SEVERAL GENETIC AND EPIGENETIC ALTERATIONS, AS WELL AS ALTERATIONS TO THE CHROMATIN STRUCTURE, WHICH OCCUR IN RESPONSE TO THE CARCINOGENIC STRESS-RELATED EVENTS THAT SUSTAIN PROLIFERATIVE SIGNALING. EVENTS SUCH AS EVADING GROWTH SUPPRESSORS, RESISTING CELL DEATH, ENABLING REPLICATIVE IMMORTALITY, INDUCING ANGIOGENESIS, AND ACTIVATING INVASION AND METASTASIS ARE READILY OBSERVED. IN ADDITION, IN CONJUNCTION WITH THESE CRITICAL DRIVERS OF CARCINOGENESIS, OTHER FACTORS RELATED TO THE ETIOPATHOGENESIS OF PCA, INVOLVING ENERGY METABOLISM AND EVASION OF THE IMMUNE SURVEILLANCE SYSTEM, APPEAR TO BE INVOLVED. IN ADDITION, WHEN CANCER SPREAD AND METASTASIS OCCUR, THE 'TUMOR MICROENVIRONMENT' IN THE BONE OF PCA PATIENTS MAY PROVIDE A WAY TO SUSTAIN DORMANCY OR SENESCENCE AND EVENTUALLY ESTABLISH A 'SEED AND SOIL' SITE WHERE PCA PROLIFERATION AND GROWTH MAY OCCUR OVER TIME. WHEN PCA IS INITIATED AND PROGRESSION ENSUES, SIGNIFICANT ALTERATIONS IN NUCLEAR SIZE, SHAPE AND HETEROCHROMATIN (DNA TRANSCRIPTION) ORGANIZATION ARE FOUND, AND KEY NUCLEAR TRANSCRIPTIONAL AND STRUCTURAL PROTEINS, AS WELL AS MULTIPLE NUCLEAR BODIES CAN LEAD TO PRECANCEROUS AND MALIGNANT CHANGES. THESE SERIES OF CELLULAR AND TISSUE-RELATED MALIGNANCY-ASSOCIATED EVENTS CAN BE QUANTIFIED TO ASSESS DISEASE PROGRESSION AND MANAGEMENT. 2012 18 1066 54 CLINICAL USE OF AMINO ACIDS AS DIETARY SUPPLEMENT: PROS AND CONS. NITROGEN SUPPLY IS PIVOTAL FOR THE MAINTENANCE OF LIFE. AMINO ACIDS CAN BE UTILIZED TO SYNTHESIZE BOTH GLUCOSE AND LIPIDS. THE OPPOSITE, I.E., PRODUCTION OF AMINO ACIDS FROM EITHER ONE OF THEM, IS NOT POSSIBLE IN THE ABSENCE OF OTHER AMINO ACIDS AS DONORS OF NITROGEN. THE QUALITY OF AMINO ACID CONTENT IN PROTEIN HAS BEEN RE-EVALUATED RECENTLY, AND THE RELEVANCE OF ESSENTIAL AMINO ACIDS HAS BEEN REPEATEDLY UNDERLINED. ESSENTIAL AMINO ACID REQUIREMENTS IN DIFFERENT MAMMALS ARE NOT IDENTICAL, AND RATIOS AMONG THEM SHOULD BE TAKEN INTO ACCOUNT WHEN PROJECTING AN EFFICIENT FORMULATION. RECENT RESEARCH HAS DEMONSTRATED THAT GENES RESPOND TO DIFFERENT QUALITIES AND QUANTITIES OF NUTRITIONAL SUPPLY, AND INCREASED PROVISION OF ESSENTIAL AMINO ACIDS INCREASES LIFESPAN IN ANIMAL EXPERIMENTS THROUGH MITOCHONDRIOGENESIS AND MAINTENANCE OF ELEVATED RATES OF SYNTHESIS OF ANTI-OXIDANT MOLECULES. MOREOVER, GENETIC EXPRESSION OF KEY CONTROLLERS OF SYNTHESIS, LIKE MTOR, MAY BE PARTICULARLY IMPORTANT FOR UNDERSTANDING SKELETAL MUSCLE MAINTENANCE. LOSSES OF MUSCLE MASS AND IMPAIRED IMMUNE FUNCTION ARE RELATED TO REDUCED PROTEIN SUPPLY, AND THERE IS INCREASING EVIDENCE THAT REGULAR ESSENTIAL AMINO ACID INTAKE AS PART OF AN ORAL DIET IS EFFECTIVE IN REVERSING MUSCLE CATABOLISM, PROMOTING MUSCLE ANABOLISM, AND RESTORING IMMUNOLOGICAL FUNCTION. THEREFORE, THE USE OF AMINO ACIDS AS SUPPLEMENTS TO DIET WOULD BE EXPANDING IN THE NEAR FUTURE. IS THIS SAFE? FEW DATA ARE AVAILABLE ON AMINO ACID TOXICITY, AND ONLY ONE ESSENTIAL AMINO ACID MAY BE CONSIDERED TO HAVE CLINICALLY RELEVANT TOXICITY: METHIONINE, BECAUSE IT IS TRANSFORMED INTO A TOXIC INTERMEDIATE, HOMOCYSTEINE, WHEN CYSTEINE SYNTHESIS IS REQUIRED BY METABOLIC NEEDS. MATCHING OF STOICHIOMETRIC RATIOS BETWEEN METHIONINE AND CYSTEINE MAY SOLVE THE PROBLEM OF SUPPLYING SUFFICIENT AMOUNTS OF SULFUR TO THE BODY. ARGININE AND GLUTAMINE ARE TWO NON-ESSENTIAL AMINO ACIDS THAN CAN BECOME "CONDITIONALLY ESSENTIAL" BECAUSE OF ELEVATED NEEDS DURING PATHOLOGICAL CONDITIONS, AND METABOLISM MAY NOT BE ABLE TO MAINTAIN THEIR CONCENTRATIONS AT SUFFICIENT LEVELS TO MATCH METABOLIC REQUIREMENTS. CHRONIC EXOGENOUS ARGININE SUPPLEMENTATION HAS NOT PROVEN TO EXERT POSITIVE CLINICAL EFFECTS IN DIFFERENT TRIALS, AND SEQUENTIAL ARTICULATION OF THE KNOWLEDGE OF INTRODUCTION OF ARGININE-DRIVEN TRANSCRIPTIONAL, TRANSLATIONAL, AND EPIGENETIC ADAPTATIONS MAY GIVE US A KEY FOR INTERPRETING THOSE PUZZLING RESULTS. 2011 19 537 36 ASYMPTOMATIC HYPERURICEMIA: IS IT REALLY ASYMPTOMATIC? PURPOSE OF REVIEW: HYPERURICEMIA IS HIGHLY PREVALENT, AFFECTING APPROXIMATELY 38 MILLION INDIVIDUALS IN THE UNITED STATES. HOWEVER, THE SIGNIFICANCE OF ASYMPTOMATIC HYPERURICEMIA - HYPERURICEMIA IN THE ABSENCE OF GOUT - CONTINUES TO BE DEBATED. RECENT FINDINGS: ASYMPTOMATIC HYPERURICEMIA RESULTS IN MONOSODIUM URATE CRYSTAL DEPOSITION IN TISSUES, WHICH MAY PROMOTE CHRONIC INFLAMMATION. INTRACELLULARLY, HYPERURICEMIA INHIBITS THE MASTER REGULATOR ADENOSINE MONOPHOSPHATE (AMP)-ASSOCIATED PROTEIN KINASE AND MAY CONDITION INNATE IMMUNE RESPONSES THROUGH DURABLE EPIGENETIC MODIFICATIONS. AT THE POPULATION LEVEL, ASYMPTOMATIC HYPERURICEMIA IS ASSOCIATED WITH MULTIPLE COMORBIDITIES, INCLUDING HYPERTENSION, CHRONIC KIDNEY DISEASE, CORONARY ARTERY DISEASE, AND DIABETES; LIMITATIONS OF THESE STUDIES INCLUDE THAT MOST ARE RETROSPECTIVE AND SOME DO NOT RIGOROUSLY DISTINGUISH BETWEEN ASYMPTOMATIC HYPERURICEMIA AND GOUT. TREATMENT STUDIES SUGGEST THAT URATE LOWERING MAY REDUCE THE RISK OF INCIDENCE OR PROGRESSION OF SOME OF THESE COMORBIDITIES; UNFORTUNATELY, MANY OF THESE TREATMENT STUDIES ARE SMALL OR FLAWED, AND NOT ALL STUDY RESULTS ARE CONSISTENT. SUMMARY: ACCUMULATING EVIDENCE SUGGESTS THAT ASYMPTOMATIC HYPERURICEMIA CONTRIBUTES TO THE COMORBIDITIES WITH WHICH IT ASSOCIATES AND THAT PROPER ASYMPTOMATIC HYPERURICEMIA TREATMENT MAY REDUCE FUTURE RISK. ADDITIONAL PROSPECTIVE TRIALS ARE NEEDED TO DEFINITELY ESTABLISH CAUSALITY AND SUPPORT DECISION-MAKING AS TO WHETHER, AND WHICH PATIENTS WITH ASYMPTOMATIC HYPERURICEMIA WOULD WARRANT URATE-LOWERING TREATMENT. 2020 20 6842 35 [MECHANISTIC ISSUES AND PREVENTION STRATEGIES TARGETING OCCUPATIONAL CARCINOGENESIS]. CARCINOGENESIS CAN BE VISUALIZED EITHER AS A MULTISTEP PROCESS (INITIATION, PROMOTION, PROGRESSION, INVASION, AND METASTASIS) OR AS A CONTINUUM OF MUTAGENIC AND MITOGENIC EVENTS, WITH THE CONTRIBUTION OF EPIGENETIC MECHANISMS. THE EXPONENTIAL GROWTH OF THE NEOPLASTIC MASS EXPLAINS THE IMPORTANCE OF SECONDARY PREVENTION (EARLY DIAGNOSIS) AND OF TERTIARY PREVENTION. PRIMARY PREVENTION, WHICH WAS SUCCESSFUL IN CONTROLLING OCCUPATIONAL CANCERS, AIMS AT MINIMIZING EXPOSURES TO CARCINOGENS IN HEALTHY SUBJECTS AND AT FAVORING THE INTAKE OF CHEMOPREVENTIVE AGENTS WITH DIETARY AND PHARMACOLOGICAL AGENTS. BESIDES CHEMICAL CARCINOGENS, OFTEN IN THE FORM OF COMPLEX MIXTURES, THE WORKPLACE MAY INVOLVE EXPOSURES TO PHYSICAL AGENTS, SUCH AS SUNLIGHT AND ARTIFICIAL ILLUMINATION SYSTEMS DELIVERING UV RADIATION, OR TO BIOLOGICAL AGENTS, SUCH AS CHRONIC VIRAL INFECTIONS (HBV, HCV, AND HIV) ASSOCIATED WITH CANCERS. A CONTROVERSIAL ISSUE IS THE OCCURRENCE OF THRESHOLD DOSES FOR CARCINOGENS IN THE WORKPLACE AND THE ENVIRONMENT. 2011