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Elevated expression and altered pattern of activity of DNA methyltransferase in liver tumors of rats fed methyl-deficient diets 总被引:3,自引:1,他引:2
DNA methyltransferase (MTase) activity in nuclear extracts from neoplastic
and preneoplastic livers of rats fed a methyl-deficient diet (MDD) is
elevated compared with that seen in the livers of control rats. Nuclear
proteins were prepared in the presence of protease inhibitors including
trans-epoxy succinyl-L-leucylamido-(4- guanido)butane and were fractionated
by isoelectric focusing. In normal, control liver, two distinct MTase
fractions were observed. In MDD-induced malignant liver, a third fraction,
in addition to the previous two, was also seen. Both the DNA substrate and
the cytosine site specificities of the third MTase fraction differ from
those of the other two fractions. The distinct MTase activity in liver
tumor has significantly more de novo MTase activity than do the MTase
fractions of normal, control liver. Thus, normal and neoplastic rat livers
differ in DNA MTase fractionation patterns and site specificities. The
altered DNA MTase activity observed in rat liver tumors caused by MDDs may
be one of the critical factors contributing to cancer formation through
abnormal DNA methylation.
相似文献
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DA O'Sullivan VE Torres PA Gabow SN Thibodeau BF King EJ Bergstralh 《American journal of kidney diseases》1998,32(6):976-983
Recent experiments in cultured cyst epithelial cells from kidneys of patients with autosomal dominant polycystic kidney disease (ADPKD) have shown that the cystic fibrosis (CF) transmembrane conductance regulator (CFTR) is present in the apical surface of these cells and mediates chloride (Cl-) and fluid secretion in vitro. To determine whether the presence of CF with the expression of mutated CFTR proteins modifies cyst formation in ADPKD, we studied a large family with both inherited diseases. ADPKD in this family is linked to PKD1. The family is composed of 26 members; 11 members with ADPKD, 4 members with CF, and 2 members with both diseases. Renal volumes measured by computerized tomography (CT), calculated creatinine clearances, and other clinical parameters in the family members with ADPKD and CF were compared with those in the family members with ADPKD alone, as well as to a large population of patients with ADPKD. The patients with CF and ADPKD, but not the CF heterozygote carriers with ADPKD, had less severe polycystic kidney and liver disease, as indicated by normal renal function; smaller renal volume, even when corrected for height and body surface area; and the absence of hypertension and liver cysts. These observations suggest that the coexistence of CF may reduce the severity of ADPKD. 相似文献
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Differential expression of a novel gene, WDNM1, in nonmetastatic rat mammary adenocarcinoma cells 总被引:5,自引:0,他引:5
Subtractive hybridization was used to investigate differences in gene expression between a metastatic clone and nonmetastatic clone of the rat mammary adenocarcinoma line DMBA-8 which differ 100-fold in their metastatic behavior. Several differentially expressed highly homologous mRNAs (600 to 900 base pairs) were identified from the nonmetastatic line which are expressed at a level 20-fold higher than in the metastatic clone. Available sequence data show no homology to published gene sequences. There is no difference between the metastatic and nonmetastatic clones regarding DNA restriction fragment sizes or copy number of the gene. Expression of this newly described gene, named WDNM1, may be an important correlate of nonmetastasis in this tumor model. 相似文献
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