Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0023418 (leukemia)
 93,477 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

One of the more consistent findings in leukemia research is the association between birth weight and childhood leukemia. Because thyroid hormones are critically involved in growth and differentiation, we speculated that hormone levels could be of significance to the development of leukemia in early life. Specifically, we hypothesized that high levels of thyroid-stimulating hormone (TSH) would be associated with a low risk of leukemia. Accordingly, high TSH (low free thyroid hormone) early after birth most likely reflects low function of the thyroid accompanied by low rate of cell turnover and so lower risk of faulty cell divisions leading to cancer. In a matched case-control study nested from all singleton children born in Denmark between 1986 and 1998, we compared levels of TSH (as measured in a neonatal screening program for congenital hypothyroidism) in 188 cases of acute lymphoblastic leukemia (ALL) and 28 of acute myeloid leukemia (AML) with levels in 1,450 and 216 matched controls, respectively. Data were analyzed using conditional logistic regression and odds ratios (OR) were adjusted for birth weight. As hypothesized, we found a decreased risk of ALL and AML associated with high TSH (OR(ALL) = 0.7 [0.5-1.0]; OR(AML) = 0.3 [0.1-1.0]). However, both conditions were also associated with low levels of TSH (OR(ALL) = 0.4 [0.2-0.7]; OR(AML) = 0.3 [0.1-1.4]). In conclusion, extreme TSH levels a few days after birth appears to be associated with a decreased risk of acute childhood leukemia.
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PMID:Neonatal level of thyroid-stimulating hormone and acute childhood leukemia. 1105 81

Hepatocyte-based gene therapy may be used to replace a missing gene product, confer proliferating ability to cultured hepatocytes, prevent allograft rejection, massively repopulate the host liver, or grow xenogeneic hepatocytes in mammalian liver. Gene transfer into isolated hepatocytes can be accomplished via nonviral or viral vectors, the viral vectors being more useful at this time. Common recombinant viruses that integrate into the host genome include murine leukemia retroviruses and lentiviruses, adenoassociated virus, and the T-antigen-deleted SV40 virus. Episomal viruses, such as adenoviruses, permit efficient gene transfer, but the transgene is lost upon proliferation of the transplanted hepatocyte in the host. Hybrid viruses that combine the high transduction efficiency of adenoviral vectors and the integrative capacity of other vectors, such as adenoassociated viruses, have been designed. Massive repopulation of the liver by transplanted hepatocytes can be achieved if a mitotic stimulus to the transplanted cells is combined with prevention of proliferation of the host hepatocytes. Treatment with a plant alkaloid or retrorsine, or preparative irradiation of the liver can be used to inhibit host hepatocellular proliferation, while partial hepatectomy, expression of Fas ligand, or thyroid hormone administration can be used as a mitotic stimulus to the transplanted cells.
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PMID:Hepatocyte-based gene therapy. 1129 90

Salicylazosulfapyridine is widely used for the treatment of ulcerative colitis and Crohn's disease. It has been beneficial in the treatment of psoriasis and rheumatoid arthritis, and it has been used in veterinary medicine for the treatment of granulomatous colitis. Salicylazosulfapyridine was nominated for toxicity and carcinogenicity testing by the National Cancer Institute on the basis of its widespread use in humans and because it is a representative chemical from a class of aryl sulfonamides. Salicylazosulfapyridine is a suspect carcinogen because reductive cleavage of the azo linkage yields a p-amino aryl sulfonamide (sulfapyridine), and a related p-amino aryl sulfonamide (sulfamethoxazole) has been shown to produce thyroid neoplasms in rats. Toxicology and carcinogenicity studies were conducted in F344/N rats and B6C3F1 mice. Rats and mice were administered salicylazosulfapyridine (96% to 98% pure) in corn oil by gavage for 16 days, 13 weeks, or 2 years. The gavage route of administration was selected for these studies because it approximates the typical route of human exposure to the chemical. Genetic toxicology studies were conducted in vitro in Salmonella typhimurium and cultured Chinese hamster ovary cells and in vivo in rat and mouse bone marrow and mouse peripheral blood cells. 16-DAY STUDY IN RATS: Groups of five male and five female rats were administered 0, 675, 1,350, or 2,700 mg salicylazosulfapyridine/kg body weight in corn oil by gavage for 16 days excluding weekends. All rats survived to the end of the study. With the exception of the 675 mg/kg male group, the final mean body weights of all dosed groups of males and females were significantly lower than those of controls. Mean body weight gains of all dosed groups were less than those of controls. Clinical findings included ruffled fur and distended abdomens in male and female rats receiving 2,700 mg/kg. Hypothyroidism, evidenced by decreased serum triiodothyronine and thyroxine concentrations and increased thyroid-stimulating hormone concentrations, occurred in 2,700 mg/kg male and female rats. The absolute and relative thymus weights of male rats receiving,350 or 2,700 mg/kg and female rats receiving 2,700 mg/kg were significantly lower than those of controls. At necropsy, all dosed rats had enlarged cecae/large intestines. Male rats receiving 1,350 mg/kg and male and female rats receiving 2,700 mg/kg had red, enlarged thyroid glands. Chemical-related microscopic lesions were present in the forestomach, thymus, thyroid gland, and pituitary gland. Minimal to mild hyperplasia of the forestomach mucosa was present in the 1,350 and 2,700 mg/kg male and female groups. Lymphoid depletion was observed in the thymus of three male and three female rats in the 2,700 mg/kg groups. Male and female rats receiving 1,350 and 2,700 mg/kg had thyroid gland follicular cell hyperplasia and an increase in thyroid-stimulating hormone producing cells in the pars distalis of the pituitary gland. 16-DAY STUDY IN MICE: Groups of five male and five female mice were administered 0, 675, 1,350, or 2,700 mg salicylazosulfapyridine/kg body weight in corn oil by gavage for 16 days excluding weekends. There were no chemical-related deaths, and final mean body weights of dosed mice were similar to those of controls. No chemical-related clinical findings were noted for male or female mice. There were no differences in triiodothyronine, thyroxine, or thyroid-stimulating hormone concentrations between dosed and control mice. There were no biologically significant differences in absolute or relative organ weights between dosed and control male and female mice. At necropsy, male mice receiving 2,700 mg/kg had enlarged cecae/large intestines. There were no biologically significant histopathologic lesions attributed to salicylazosulfapyridine administration. 13-WEEK STUDY IN RATS: Groups of 10 male and 10 female rats were administered 0, 84, 168.8, or 337.5 mg salicylazosulfapyridine/kg body weight in corn oil by gavage for 13 weeks. All rats survived to the end of the study. The finaludy. The final mean body weights of dosed male rats were similar to those of controls; the final mean body weights and body weight gains of dosed females were significantly lower than those of controls. No chemical-related clinical findings were noted in dosed male or female rats during the 13-week study. No significant differences in hematology or urinalysis parameters between control and dosed rats were observed. The absolute and relative right kidney weights of 337.5 mg/kg females were significantly greater than those of controls. At necropsy, some 337.5 mg/kg male rats had red, enlarged thyroid glands. Histopathologic changes were noted primarily in the thyroid gland and pituitary gland of males and females in the 337.5 mg/kg groups. The thyroid gland lesions observed were similar to those present in the 16-day study. Nine male rats receiving 168.8 mg/kg and ten male and seven female rats receiving.5 mg/kg had minimal but consistent changes in thyroid gland follicular cells. In the pituitary gland of 337.5 mg/kg males and females, the thyroid-stimulating hormone producing cells were enlarged and contained pale-staining cytoplasm and prominent Golgi complexes. Decreased serum triiodothyronine and thyroxine concentrations and increased thyroid-stimulating hormone concentration, similar to differences observed in the 16-day study, occurred in 337.5 mg/kg male rats; thyroid hormone concentrations were not affected in female rats. Sperm motility of all dosed groups of males was significantly lower than that of controls. Vaginal cytology parameters of dosed groups of females were similar to those of controls. 13-WEEK STUDY IN MICE: Groups of 10 male and 10 female mice were administered 0, 675, 1,350, or 2,700 mg salicylazosulfapyridine/kg body weight in corn oil by gavage for 13 weeks. All mice survived to the end of the study. The final mean body weights of dosed male and female mice were similar to those of controls. The mean body weight gains of 1,350 and 2,700 mg/kg male mice were less than that of controls. No chemical-related clinical findings were noted in dosed male or female mice during the 13-week study. There was minimal evidence of a responsive anemia in mice in the 13-week study. The anemia was probably related to a methemoglobinemia. There were minimal decreases in thyroxine concentration in all dosed groups of male and female mice in the -week study. There were, however, no differences in triiodothyronine and thyroid-stimulating hormone concentrations between dosed and control animals. Absolute and relative liver weights of all groups of dosed male and female mice were significantly greater than those of controls. There were no chemical-related gross lesions. Microscopic evaluation of the liver revealed centrilobular hypertrophy in five 1,350 mg/kg and all 2,700 mg/kg male mice. The right cauda weight of the 1,350 mg/kg group and the right epididymis weights of all dose groups were significantly lower than those of controls. There was no evidence of chemical-related alteration in the vaginal cytology parameters of female mice. 2-YEAR STUDY IN RATS: Groups of 60 male and 60 female rats were administered 84, 168, or 337.5 mg salicylazosulfapyridine/kg body weight in corn oil by gavage for up to 105 weeks. Groups of 70 male and 60 female rats were administered the corn oil vehicle by gavage for up to 105 weeks. A stop-exposure group of 70 male rats was administered 337.5 mg/kg salicylazosulfapyridine in corn oil by gavage for 6 months, after which animals received the corn oil vehicle by gavage for the remainder of the 2-year study. Ten animals from the vehicle control male group and 10 animals from the 337.5 mg/kg stop-exposure group were evaluated at 6 months; animals from each core-study group were evaluated at 15 months. Survival, Body Weights, and Clinical Chemistry: Survival of 337.5 mg/kg male core-study rats was significantly lower than that of controls; survival of 84 and 168 mg/kg core-study males, all groups of dosed females, and the stop-exposure male group was similar to controls. Mean body weights of core-study males and stop-exposure males were similar to controls throughout the study. From week 45 to the end of the study, females in the 337.5 mg/kg group had mean body weights that were lower than those of controls. The serum thyroxine concentration in 337.5 mg/kg core-study males at study termination was minimally lower than that of controls; the serum thyroid-stimulating hormone, triiodothyronine, and reverse triiodothyronine concentrations of dosed males and females were similar to those of controls. Pathology Findings: Administration of salicylazosulfapyridine for 2 years was associated with transitional epithelial papilloma in the urinary bladder of male rats and may have been associated with transitional epithelial papilloma of the kidney and of the urinary bladder of female rats. Nonneoplastic effects in the urinary bladder and kidney of male and female rats and in the spleen of male rats were also observed. Dosed male and female rats had increased incidences of grossly and microscopically observed urinary bladder concretions (diagnosed grossly as calculi at necropsy); male and female rats that developed transitional epithelial papillomas of the urinary bladder had grossly observed concretions (calculi) in the urinary bladder at necropsy. The microscopic neoplastic and nonneoplastic urinary bladder and kidney effects observed in dosed male rats during the 2-year continuous study did not occur in dosed rats during the 2-year stop-exposure study, nor were there gross observations of concretions (calculi) at necropsy. The incidences of mononuclear cell leukemia in male and female rats were decreased. The thyroid gland hyperplasia seen in the -week study was not observed in the 2-year study, and there was no evidence of chemical-related thyroid gland follicular cell adenomas or carcinomas. 2-YEAR STUDY IN MICE: Groups of 60 male and 60 female mice were administered 0, 675, 1,350, or 2,700 mg salicylazosulfapyridine/kg body weight in corn oil by gavage for up to 104 weeks. Ten animals from each group were evaluated at 15 months. Survival, Body Weights,and Clinical Chemistry: Survival of all the dosed groups of male and female mice was similar to that of controls. Mean body weights of 675 and 1,350 mg/kg male and female mice were similar to controls throughout the study. From week 12 to the end of the study, 2,700 mg/kg male mice had mean body weights that were lower than those of controls. From week 14 to the end of the study, the 2,700 mg/kg female mice had mean body weights that were lower than those of controls. There were no chemical-related differences in triiodothyronine, reverse triiodothyronine, thyroxine, or thyroid-stimulating hormone concentrations between dosed and control mice at the 15-month evaluation. Pathology Findings: Exposure of mice to salicylazosulfapyridine in corn oil by gavage for 2 years was associated with increased incidences of hepatocellular neoplasms in males and females. Nonneoplastic effects in the liver and spleen were also observed in male and female mice. The incidences of forestomach squamous cell papilloma in females and forestomach hyperplasia in males and females were decreased. GENETIC TOXICOLOGY: Salicylazosulfapyridine was not mutagenic in Salmonella typhimurium strains TA97, TA98, TA100, or TA1535, and it did not induce sister chromatid exchanges or chromosomal aberrations in cultured Chinese hamster ovary cells. These in vitro assays were performed with and without S9 metabolic activation enzymes. Results from in vivo mouse bone marrow chromo somal aberration tests were uniformly negative, while results of micronucleus assays performed on male or female mice exposed to salicylazosulfapyridine for periods ranging from 3 days to weeks were positive. Micronucleus tests in male mice for shorter exposure times (1 to 2 days) yielded negative or very weakly positive results. A three-treatment (72-hour exposure time) micronucleus test performed in male rats yielded equivocal results. Overall, results of these in vivo assays indicate that salicylazosulfa pyridine is capable of inducing chromosomal damage, possibly in the form of aneuploidy, in mouse bone marrow cells after multiple administrations. CONCLUSIONS: Under the conditions of these 2-year gavage studies, there was some evidence of carcinogenic activity of salicylazosulfapyridine in male and female F344/N rats based on increased incidences of neoplasms in the urinary tract. There was an increased incidence of transitional epithelial papilloma of the urinary bladder in males and a low incidence of rare transitional epithelial papillomas of the kidney and of the urinary bladder in females. There was clear evidence of carcinogenic activity of salicylazosulfapyridine in male and female B6C3F1 mice based on increased incidences of hepatocellular neoplasms. Increased incidences of nonneoplastic lesions of the urinary bladder and kidney in male and female rats and of the spleen in male rats were observed. Increased incidences of nonneoplastic lesions of the liver and spleen in male and female mice were observed. Decreased incidences of mononuclear cell leukemia in male and female rats were related to salicylazosulfapyridine administration. Decreased incidences of forestomach squamous cell papilloma in female mice and forestomach hyperplasia in male and female mice were related to salicylazosulfapyridine administration. Synonyms: 2-Hydroxy-5-[[4-[2-(pyridinylamino)sulfonyl]phenyl]azo]benzoic acid; 5-[p- (2-pyridylsulfamoyl)phenylazo]salicylic acid; sulfasalazine; salazosulfapyridine; 5-[4-(2-pyridylsulfamoyl)phenylazo]-2-hydroxybenzoic acid; 4-(pyridyl-2-amidosulfonyl)-3'-carboxy-4'-hydroxyazobenzene; sulphasalazine Trade names: Azopyrin, Azulfidine, Benzosulfa, Colo-Pleon, Reupirin, Salazopyrin
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PMID:NTP Toxicology and Carcinogenesis Studies of Salicylazosulfapyridine (CAS No. 599-79-1) in F344/N Rats and B6C3F1 Mice (Gavage Studies). 1258 19

3,3'-Dimethylbenzidine dihydrochloride is one of five chemicals being evaluated in 2-year carcinogenicity and toxicity studies as part of the NTP's Benzidine Dye Initiative. This Initiative was designed to evaluate representative benzidine congeners, benzidine congener-derived dyes, and benzidine-derived dyes. 3,3'-Dimethylbenzidine dihydrochloride was nominated for study because of the potential for human exposure during production of bisazobiphenyl dyes and because benzidine, a structurally related chemical, is a known human carcinogen. Toxicology and carcinogenesis studies were conducted by administering 3,3'-dimethylbenzidine dihydrochloride (approximately 99% pure) in drinking water to groups of F344/N rats of each sex for 14 days, 13 weeks, or 9 or 14 months. The 14-month exposures were planned as 24-month exposures but were terminated early because of rapidly declining animal survival, due primarily to neoplasia. These studies were performed only in rats because similar studies were being performed in mice at the National Center for Toxicological Research (NCTR). Hematologic and serum chemical analyses and thyroid hormone determinations were conducted in conjunction with the 13-week and 9-month studies. Genetic toxicology studies were conducted in Salmonella typhimurium, Chinese hamster ovary (CHO) cells, and Drosophila melanogaster. 14-Day Studies: Rats were exposed to 3,3'-dimethylbenzidine dihydrochloride in drinking water at doses ranging from 600 to 7,500 ppm. All five males and one female in the 7,500 ppm group and 1/5 males in the 5,000 ppm group died. Final mean body weights were decreased in males receiving 1,250 ppm or more and in all exposed females, and final mean body weights of animals receiving 2,500 ppm or more were lower than initial weights. Water consumption decreased with increasing chemical concentration. Compound-related effects observed in rats receiving 5,000 ppm or more included minimal to slight hepatocellular necrosis, accumulation of brown pigment (presumably bile) in individual hepatocytes, increased severity of nephropathy relative to controls, and severe lymphocytic atrophy of the thymus. Treated animals also showed an increased severity of atrophy of the bone marrow relative to controls, varying degrees of lymphocytic atrophy of the mandibular and mesenteric lymph nodes and spleen, increased vacuolization and necrosis of cells of the adrenal cortex, focal acinar cell degeneration in the pancreas, and, in males, increased immature sperm forms in the testis and epididymis. 13-Week Studies: 3,3'-Dimethylbenzidine dihydrochloride was administered in drinking water at doses of 300, 500, 1,000, 2,000, and 4,000 ppm. All rats receiving 4,000 ppm and 4/10 males and 1/10 females receiving 2,000 ppm died before the end of the studies. Depressions in final mean body weight relative to controls ranged from 12% to 48% for males and from 9% to 42% for females. Water consumption decreased with increasing dose. At compound concentrations of 300 to 2,000 ppm, mean water consumption was 29% to 83% of control values. Compound-related effects included an increase in the severity of nephropathy relative to controls; hepatocellular necrosis and accumulation of brown pigment (presumably bile) in sinusoidal lining cells; lymphocytic atrophy of the thymus, spleen, and mandibular and mesenteric lymph nodes; atrophy of the bone marrow in the higher-dose groups; degeneration of pancreatic acinar cells; and, in males, immature sperm forms in the testis and epididymis. Decreases in serum triiodothyronine (T3) values were observed in exposed females, and decreases in mean thyroxin (T4) concentrations in exposed males and females; no significant changes were observed in thyroid stimulating hormone (TSH) levels in exposed rats. Based on the decreased survival, reductions in water consumption and body weight gain, and chemical-induced hepatocellular and renal lesions observed in the 13-week studies, the doses selected for the 9- and 14-month drinking water studies of 3,3'-dimethylbenzidine dihydrochloride were 0, 3 3,3'-dimethylbenzidine dihydrochloride were 0, 30, 70, and 150 ppm. Seventy rats of each sex were used in the control group, 45 in the low-dose group, 75 in the mid-dose group, and 70 in the high-dose group. 9-Month Studies: Ten rats of each sex in the control and 150 ppm dose groups were evaluated after 9 months. Chemical-related effects observed in exposed animals included alveolar/bronchiolar carcinoma in one male, basal cell carcinoma of the skin in one male, a squamous cell carcinoma of the oral cavity in one female, preputial gland carcinoma in two males, clitoral gland carcinoma in three females, adenocarcinoma of the small intestine in two males, Zymbal's gland carcinoma in two males and three females, hepatocellular carcinoma in two males, and adenomatous polyps of the large intestine in three males. Other effects seen in dosed rats included focal cellular alteration in the liver, lymphoid atrophy in the spleen, and increased severity of nephropathy relative to controls. An increase in serum T3 values was observed in exposed males, and a decrease in mean T4 concentrations in exposed males and females. TSH concentrations were increased in exposed male and female rats. Body Weights and Survival in the 14-Month Studies: The average amount of 3,3'-dimethylbenzidine dihydrochloride consumed per day was approximately 1.8, 4.0, or 11.2, mg/kg for low-, mid-, or high-dose male rats and 3.0, 6.9, or 12.9 mg/kg for low-, mid-, or high-dose female rats. The mean body weight of high-dose males was about 85% of the control value by week 28. By the end of the study, mean body weights of low-, mid-, and high-dose males were 97%, 92%, and 70% of the control values, respectively. Mean body weights of high- and mid-dose females were about 85% of the control values at week 32 and week 44, respectively. At the end of the study, mean body weights of exposed females were about 94%, 81%, and 74% of the control values for low-, mid-, and high-dose groups, respectively. Because of extensive neoplasia, many exposed males and females were dying or were sacrificed moribund in the first year, and all high-dose males died by week 55. The studies were terminated at weeks 60 to 61, at which time the group survivals were male: control, 60/60, low dose, 41/45; mid dose, 50/75; high dose, 0/60; female: 59/60; 39/45; 32/75; 10/60. Nonneoplastic Effects in the 14-Month Studies: Increases in nonneoplastic lesions in dosed rats included cystic degeneration and foci of cellular alteration in the liver; exacerbation of nephropathy; and focal or multifocal hyperplasia of the Zymbal's gland, preputial and clitoral glands, and alveolar epithelium. Neoplastic Effects in the 14-Month Studies: Neoplasms were observed in exposed rats at many sites: skin, Zymbal's gland, preputial and clitoral glands, liver, oral cavity, small and large intestine, mammary gland, lung, brain, and mesothelium. The incidence of these neoplastic effects in male and female rats is summarized in the table at the end of this section (see page 8 of the Technical Report). Genetic Toxicology: 3,3'-Dimethylbenzidine dihydrochloride was mutagenic in Salmonella typhimurium strain TA98 with exogenous metabolic activation; it was not mutagenic in strains TA100, TA1535, or TA97 with or without activation. 3,3'-Dimethylbenzidine dihydrochloride induced sister-chromatid exchanges (CHO) and chromosomal aberrations in CHO cells in the absence of exogenous metabolic activation; these effects were not evident in test with S9 activation. Sex-linked recessive lethal mutations were induced in germ cells of adult male Drosophila melanogaster administered 3,3'-dimethylbenzidine dihydrochloride in feed or by injection. No reciprocal translocations occurred in D. melanogaster germ cells following exposure to 3,3'-dimethylbenzidine dihydrochloride. Conclusions: Under the conditions of these 14-month drinking water studies, there was clear evidence of carcinogenic activity of 3,3'-dimethylbenzidine dihydrochloride for male F344/N rats, as indicated by benign and malignant neoplasms of the skin, Zymbal's gland, preputial gland, liver, oral cavity, small and large intestine, lung, and mesothelium. Increased incidences of neoplasms of the brain may have been related to chemical administration. There was clear evidence of carcinogenic activity for female F344/N rats, as indicated by benign and malignant neoplasms of the skin, Zymbal's gland, clitoral gland, liver, oral cavity, small and large intestine, mammary gland, and lung. Increased incidences of neoplasms of the brain and mononuclear cell leukemia may have been related to chemical administration. Synonyms: o-tolidine dihydrochloride; 3,3'-dimethylbiphenyl-4,4'-diamine dihydrochloride; 3,3'-dimethylbiphenyl-4,4'-biphenyldiamine dihydrochloride; 4,4'-diamino-3,3'-dimethylbiphenyl dihydrochloride
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PMID:NTP Toxicology and Carcinogenesis Studies of 3,3'-Dimethylbenzidine Dihydrochloride (CAS No. 612-82-8) in F344/N Rats (Drinking Water Studies). 1263 69

Several viruses target cellular promyelocytic leukemia (PML)-nuclear bodies (PML-NBs) to induce their disruption, marked morphological changes in these structures or the relocation to PML-NB components to the cytoplasm of infected cells. PML conversely interferes with viral replication. We demonstrate that PML acts as a coactivator for the human T-cell leukemia virus type 1 (HTLV-1) Tax oncoprotein without direct binding. Tax was identified within interchromatin granule clusters (IGCs)/RNA splicing bodies (SBs), not PML-NBs; Tax expression did not affect PML-NB formation. Moreover, PML and CBP/p300 cooperatively activated Tax-mediated HTLV-1-LTR-dependent gene expression. Interestingly, two PML mutants, PML-RAR and PMLDelta216-331, which fail to form PML-NBs, could also coactivate Tax-mediated trans-acting function but had no effect on retinoic acid receptor (RAR)- or p53-dependent gene expression. In contrast, SMRT (silencing mediator for retinoic acid and thyroid hormone receptors), a nuclear corepressor found within the matrix-associated deacetylase (MAD) nuclear body, relocalized into Tax-associated nuclear bodies upon coexpression with Tax. SMRT coactivated the trans-acting function of Tax through direct binding. Coexpression of SMRT and PML resulted in an additive activation of Tax trans-acting function. Thus, crosstalk between distinct nuclear bodies may control Tax function.
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PMID:Distinct nuclear body components, PML and SMRT, regulate the trans-acting function of HTLV-1 Tax oncoprotein. 1264 64

Fms-like tyrosine kinase 3 (Flt3) is a type III receptor tyrosine kinase (RTK). Between 20% and 30% of acute myeloid leukemia (AML) patients have either an internal tandem duplication (ITD) of the juxtamembrane region or a point mutation of the Flt3 receptor leading to the constitutive activation of downstream signaling pathways and aberrant cell growth. The silencing mediator of retinoic and thyroid hormone receptors (SMRT) corepressor mediates transcriptional repression by interacting with transcription factors such as the promyelocytic leukemia zinc finger (PLZF) protein. Previous reports indicate that SMRT interaction with transcription factors can be disrupted by phosphorylation through activation of RTK pathways. We report here that the Flt3-ITD interferes with the transcriptional and biologic action of the PLZF transcriptional repressor. In the presence of Flt3-ITD, PLZF-SMRT interaction was reduced, transcriptional repression by PLZF was inhibited, and PLZF-mediated growth suppression of leukemia cells was partially blocked. Furthermore, overexpression of Flt3-ITD led to a partial relocalization of SMRT protein from the nucleus to the cytoplasm. Nuclear export was dependent on the SMRT receptor interaction domain (RID), and Flt3-ITD enhances the binding of nuclear-cytoplasm shuttling protein nuclear factor-kappaB-p65 (NFkappaB-p65) to this region. These data suggest that activating mutations of Flt3 may disrupt transcriptional repressor function resulting in aberrant gene regulation and abnormal leukemia cell growth.
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PMID:The Flt3 internal tandem duplication mutant inhibits the function of transcriptional repressors by blocking interactions with SMRT. 1498 81

1alpha,25-Dihydroxyvitamin D(3) [1,25-(OH)(2)D(3)], the active metabolite of vitamin D(3), is known for the maintenance of mineral homeostasis and normal skeletal architecture. However, apart from these traditional calcium-related actions, 1,25-(OH)(2)D(3) and its synthetic analogs are being increasingly recognized for their potent antiproliferative, prodifferentiative, and immunomodulatory activities. These actions of 1,25-(OH)(2)D(3) are mediated through vitamin D receptor (VDR), which belongs to the superfamily of steroid/thyroid hormone nuclear receptors. Physiological and pharmacological actions of 1,25-(OH)(2)D(3) in various systems, along with the detection of VDR in target cells, have indicated potential therapeutic applications of VDR ligands in inflammation (rheumatoid arthritis, psoriatic arthritis), dermatological indications (psoriasis, actinic keratosis, seborrheic dermatitis, photoaging), osteoporosis (postmenopausal and steroid-induced osteoporosis), cancers (prostate, colon, breast, myelodysplasia, leukemia, head and neck squamous cell carcinoma, and basal cell carcinoma), secondary hyperparathyroidism, and autoimmune diseases (systemic lupus erythematosus, type I diabetes, multiple sclerosis, and organ transplantation). As a result, VDR ligands have been developed for the treatment of psoriasis, osteoporosis, and secondary hyperparathyroidism. Furthermore, encouraging results have been obtained with VDR ligands in clinical trials of prostate cancer and hepatocellular carcinoma. This review deals with the molecular aspects of noncalcemic actions of vitamin D analogs that account for the efficacy of VDR ligands in the above-mentioned indications.
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PMID:Noncalcemic actions of vitamin D receptor ligands. 1579 98

Fms-like tyrosine kinase 3 (Flt3) is a type III receptor tyrosine kinase. The internal tandem duplication (ITD) of the juxtamembrane region of this receptor is the most prevalent mutation in acute myeloid leukaemia (AML). The silencing mediator of retinoic and thyroid hormone receptors (SMRT) co-repressor recruits histone deacetylases (HDAC) and mediates transcriptional repression by interacting with various transcription factors. We recently reported that Flt3-ITD interferes with the transcriptional and biological action of promyelocytic leukaemia zinc finger transcriptional repressor by dissociating it from SMRT. In this study, we aimed to clarify whether the repressional activity of other well-known oncoproteins, such as AML1/Runx1 (AML1), is also affected by Flt3-ITD. We verified that the repression activity of AML1B, the isoform of AML1, is dependent on HDAC activity by using HDAC inbitor trichostatin A in GAL4 reporter assays. Mammalian two-hybrid assays demonstrated that this protein interacts with SMRT. Furthermore, this AML1B-SMRT interaction was disrupted by the overexpression of Flt3-ITD, leading to the reduction of AML1B repression activity. Additionally, we showed AML1B repression target, p21 (WAF1/CIP1), was aberrantly expressed in Flt3-ITD stably expressed BaF3 cells. Taken together, Flt3-ITD disrupts transcriptional repressor functions resulting in aberrant gene regulation in leukaemic cells.
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PMID:AML1B transcriptional repressor function is impaired by the Flt3-internal tandem duplication. 1604 94

The thyroid gland is afflicted in several endocrine, autoimmune, and malignant diseases. Previous studies detected immunoreactivity against proteins of a human intracisternal A-type retroviral particle type-I (HIAP-I) in serum samples from the majority of patients with Graves' disease, an autoimmune disease of the thyroid that can also affect other organs, most prominently the eyes. To determine whether hyperthyroid animals might provide a model for the retroviral involvement in thyroid autoimmunity, serum samples from 32 cats (21 hyperthyroid and 11 controls) and 10 hypothyroid dogs were examined for immunoreactivity with HIAP-I using a Western blot technique. Of the 21 hyperthyroid cats 15 (71.4%) were HIAP-I positive, while only 2 of 11 (11.8%) control animals without endocrine pathology were positive. No significant correlations were seen between HIAP seroreactivity and serum thyroid hormone levels (T3 and T4), age, gender, treatment history, vaccination status, or weight. No seroreactivity to HIAP-I was detected in hypothyroid dogs. An examination of HIAP-I reactivity in feline leukemia virus (FeLV)-seroconverting cats found that 7/9 (78%) animals viremic for FeLV-A showed an alteration in HIAP serology, whereas only 1/7 (14%) nonviremic animals showed a change in HIAP-I serology. These results suggest that it may be possible to develop an animal (feline) model for the role of retroviruses in thyroid autoimmune diseases.
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PMID:Seroreactivity to A-type retrovirus proteins in a subset of cats with hyperthyroidism. 1627 11

The authors review the epidemiology, clinical manifestations, diagnosis, and treatment of fungal thyroiditis cases previously reported in the medical literature. Aspergillus was by far the most common cause of fungal thyroiditis. Immunocompromised patients, such as those with leukemia, lymphoma, autoimmune diseases, and organ-transplant patients on pharmacological immunosuppression were particularly at risk. Fungal thyroiditis was diagnosed at autopsy as part of disseminated infection in a substantial number of patients without clinical manifestations and laboratory evidence of thyroid dysfunction. Local signs and symptoms of infection were indistinguishable from other infectious thyroiditis and included fever, anterior cervical pain, thyroid enlargement sometimes associated with dysphagia and dysphonia, and clinical and laboratory features of transient hyperthyroidism due to the release of thyroid hormone from follicular cell damage, followed by residual hypothyroidism. Antemortem diagnosis of fungal thyroiditis was made by direct microscopy and culture of a fine-needle aspirate, or/and biopsy in most cases. Since most patients with fungal thyroiditis had disseminated fungal infection with delay in diagnosis and treatment, the overall mortality was high.
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PMID:Fungal thyroiditis: an overview. 1648 84


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