Gene/Protein
Disease
Symptom
Drug
Enzyme
Compound
Pivot Concepts:
Gene/Protein
Disease
Symptom
Drug
Enzyme
Compound
Target Concepts:
Gene/Protein
Disease
Symptom
Drug
Enzyme
Compound
Query: EC:3.1.22.1 (
DNase II
)
429
document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)
This study examines the relationship between unbalanced growth,
DNase II
activity, DNA breakage and cell survival during the exposure of L5178Y cells to hydroxyurea (HU), excess thymidine (dThR) or HU with excess of four deoxyribonucleosides (dNR). It has been found that in the cells arrested by HU or dThR, but still appearing viable with the trypan blue exclusion test, Protein/DNA imbalance and abnormal cell volume are correlated with enhancement of
DNase II
activity in the cells and in the medium and with moderate increase in parental DNA breakage. The incidence of DNA breaks was markedly potentiated in the presence of non-toxic concentration of
caffeine
(
CAF
), used to inhibit DNA repair. In HU+dNR arrested cells, in which unbalanced growth was abolished, enhancement of
DNase II
activity and of DNA breakage in the presence or absence of
CAF
was substantially prevented. Comparison of posttreatment cell survival in the presence or absence of
CAF
confirmed the differential effect of
CAF
: while in HU or dThR arrested cells the presence of
CAF
induced marked cell killing, in HU+dNR arrested cells the influence of
CAF
was negligible. Only a slight effect of
CAF
was observed in cells in which dThR-induced arrest and unbalanced growth were reversed by deoxycytidine (dCR) addition. It is suggested that the involvement of DNA nucleases in the unbalanced growth-induced overproduction of numerous hydrolytic enzymes, with their progressive leakage through the cell membranes, can lead to progressive DNA digestion. DNA breaks produced in this way are normally, at least partly, repaired. Concomitant exposure of such cells to DNA repair inhibitor can markedly enhance the level of breaks, leading to potentiation of unbalanced growth-induced cell killing.
...
PMID:Mechanism of unbalanced growth-induced cell damage. II. A probable relationship between unbalanced growth, DNA breakage and cell death. 377 83
