Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:3.1.30.1 (S1 nuclease)
 3,660 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

We have investigated whether the translocated and the untranslocated human c-myc oncogenes of Burkitt lymphoma cells are equally or differentially expressed in host mouse B cells. The human c-myc mRNA levels in somatic cell hybrids between mouse plasmacytoma cells and Burkitt lymphoma cells with either the t(8;14) or the t(2;8) chromosome translocation were determined by using the nuclease S1 protection procedure. Although both the human parental lines and the hybrid cells carrying the translocated c-muc oncogene expressed high levels of human specific c-myc transcripts, the hybrid cells carrying the untranslocated c-myc gene on normal chromosome 8 did not contain human specific c-myc mRNA. These results suggest that the translocated human c-myc oncogene has escaped the normal transcriptional control to which the untranslocated c-myc gene remains subjected. This interpretation is also supported by the finding that the expression of the c-myc genes of lymphoblastoid cells and of HL-60 promyelocytic leukemia cells are repressed when they are transferred into a mouse plasmacytoma background. The ability of the translocated c-myc oncogene to escape the normal transcriptional control occurring in B cells may be important for the expression of B cell neoplasia in mouse and man. We have also transferred the Burkitt 14q+ chromosome carrying a translocated c-myc oncogene into mouse LM-TK- fibroblasts and studied the levels of human c-myc transcripts in the hybrids. Because the levels of human c-myc transcripts in the fibroblast hybrids are dramatically decreased in comparison to the plasmacytoma hybrids, we conclude that the levels of transcripts of the translocated c-myc oncogene depend on the differentiated state of the cells harboring the translocated chromosome.
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PMID:Differential expression of the normal and of the translocated human c-myc oncogenes in B cells. 630 54

Variety of synthetic steroids are reported to be mutagenic as well as carcinogenic. The mutagenic and carcinogenic nature of these compounds have been related to their potential of being reactive to genetic material and production of reactive oxygen species. Here we have analyzed the action of aziridinyl steroid on calf thymus DNA and human promyelocytic leukemia cell line HL-60 under in vitro conditions. Calf thymus DNA when treated with various doses of aziridinyl steroid induced a high degree of stand separation and sensitivity/susceptibility to S1 nuclease hydrolysis. The treatment also induced an increasing number of strand breaks per molecule of DNA as determined by alkaline unwinding assay. Relatively higher doses of steroid, however, displayed a reduced susceptibility to S1 nuclease hydrolysis and did not increase the number of strand breaks in DNA. Moreover, the high dose treatments result increased melting temperature and an enhanced rate of reanealing after thermal denaturation, indicating that interstrand crosslinks are induced at higher doses of steroid treatment. Moreover, steroid treatment caused cell death in human promyelocytic leukemia cell line HL-60 and induced DNA degradation, characteristic of apoptosis. The test steroid has the ability to produce reactive oxygen intermediates (ROI) as determined by chemical methods. Incorporation of oxygen radical scavengers into the system blocked the damaging effect of steroid in calf thymus DNA and HL-60 cells. These observations strongly suggest that aziridinyl steroid, a pharmaceutical, damages mammalian DNA and induces apoptosis by the production of ROI in the test system.
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PMID:Aziridinyl steroid-induced lesions in DNA and apoptosis in promyelocytic leukemia cells. 944 30