Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:3.1.22.1 (DNase II)
 429 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Bleomycin (BLM) exclusively affects thymidine-containing compounds such as DNA and polydeoxyribonucleotides by releasing free thymine and leaving aldehyde functions. Molecular morphology and base sequence of the DNA strongly influence BLM activity. High BLM concentrations, besides modifying DNA into oligothyminic or athyminic nucleic acids, cause strand scissions. Enzymatic DNA and RNA synthesis is strongly influenced by BLM. The inhibition in DNA-dependent DNA polymerase and DNA-dependent RNA polymerase assays is of the non-competitive type. Protein biosynthesis in in vitro systems is not affected by BLM even at high concentrations. BLM turns out to be a strong inhibitor of DNase I and of DNase II; the inhibition is of the competitive type. The enzymatic activities of nucleases using RNA as substrate (RNase A, RNase B, Rnase T1, venom phosphodiesterase I and spleen phosphodiesterase II) are not influenced by this antibiotic. The antibiotic reduces cell proliferation (L5178y mouse lymphoma cells) in vitro in low concentrations by cytostasis and at higher concentrations by cytotoxicity. In BLM-treated L5178y cells, DNA synthesis is strongly reduced, while RNA and protein synthesis are not affected. In vivo, using growing quail oviducts, cell proliferation and cytodifferentiation are markedly inhibited after BLM treatment. This is attributed to the observed inhibition of DNA synthesis. RNA and protein synthesis as well as gene expression are not influenced by BLM under the conditions used. The selective inhibition of DNA synthesis in vivo may be caused by the following mechanisms: (1) competition of BLM with RNA; (2) blocking of the accessibility of DNA in chromatin to BLM, and (3) dependence from the repair processes. BLM inhibits growth of sarcomas, induced by oncogenic RNA viruses in vivo; well-developed tumours show regression after BLM treatment. Transformation of chick embryo fibroblasts by oncogenic RNA viruses in vitro and growth of these viruses is blocked by BLM; the most sensitive period for BLM inhibition is the time during the first period (integration of viral genome into cellular genome?) after infection.
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PMID:Effect of bleomycin on DNA, RNA, protein, chromatin and on cell transformation by oncogenic RNA viruses. 6 69

Forty-seven human leukaemia/lymphoma cell lines belonging to myelocytic, monocytic, non-T/non-B, T-, and B-lineage and representing different levels of maturation as well as fresh cells from normal and leukaemic subjects were examined for immunological markers and cytochemically for acid phosphatase, alkaline phosphatase, alpha-naphthyl acetate esterase (pH 5.8 and 8.0), alpha-naphthyl butyrate esterase (pH 5.8 and 8.0), non-specific esterase, chloroacetate esterase, chymotrypsin-like protease, deoxyribonuclease II, beta-glucuronidase, sudan black, and periodic acid Schiff's staining. Strong sudan black, nonspecific esterase, and chloroacetate esterase reaction was obtained only for myelocytic and monocytic cell lines with the reaction intensity increasing progressively in more mature cells. Focal acid phosphatase reaction like T-ALL was found in all T-ALL cell lines, whereas myeloid/monocytoid lines had semicircular distribution and B-cell lines cytoplasmic distribution of activity. Acid phosphatase activity appeared to decline with maturation along both myeloid and T-cell lineage. High activity of alpha-naphthyl acetate esterase and alpha-naphthyl butyrate esterase both at pH 5.8 and 8.0 and of beta-glucuronidase was found in myeloid/monocytoid lines although both B- and T-cell lines in contrast to peripheral blood B-cells also had significant esterase activity. alpha-Naphthyl butyrate esterase activity declined with increasing cell maturation along myeloid lineage. Except for weak activity in two B-cell lines alkaline phosphatase was not detected in any cell lines. Monocyte esterase activity was inhibited by sodium fluoride whereas acid phosphatase, only from hairy cell leukaemia line, was resistant to L-tartarate. Although periodic acid Schiff's staining could not distinguish myeloid, T-, B-, or non-T/non-B cell lines it gave characteristic reaction (large number of coarse granules against a clear background forming a ring around the nucleus) with erythroblastic leukaemia cell line and along myeloid series its intensity increased in more mature cells. Deoxyribonuclease II and chymotrypsin-like protease staining were not discriminatory. The results of this study show that cytochemical staining characteristics of various leukaemia/lymphoma cell lines are comparable to those of corresponding cells from patients and that the intensity and pattern of expression of these activities are related to cell type and degree of cell maturation. These studies give further credence to the use of these cell lines in cell differentiation, differential drug cytotoxicity, and many other studies.
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PMID:Cytochemical comparison of immunologically characterized human leukaemia/lymphoma cell lines representing different levels of maturation. 619 Apr 91