7,12-Dimethylbenz[a]anthracene plus near-u.v. light initiates DNA damage and repair in Chinese hamster cells.
7,12-Dimethylbenz[a]anthracene plus near-u.v. light initiates DNA damage and repair in Chinese hamster cells.
复制标题
7,12-二甲基苯并[a]蒽加近紫外光
DOI：
10.1093/carcin/8.10.1439
复制
发表时间：
1987
期刊：
影响因子：
4.7
通讯作者：
Elkind,MM
中科院分区：
文献类型：
--
作者：
Utsumi,H;Kitani,H;Chang-Liu,CM;Elkind,MM
Earlier results on the photodynamic action of several carcinogenic polycyclic aromatic hydrocarbons, and particularly 7,12-dimethylbenz[a]anthracene (DMBA), have been extended to determine if DMIBA + near-u.v. light produces damage to DNA. DMEA by itself (30 min,∼24°C) introduces relatively few breaks into genomic DNA. The addition of near -u.v. light, however, inserts large numbers of single-strand breaks in a dose-dependent way. Incubation following exposure initially results in the rapid repair of these breaks. A primary role for DNA damage in photodynamic cell killing is not supported by other observations, however. First, caffeine, an inhibitor of radiation-associated DNA repair processes, has only a minor effect on the oxygen-dependent killing of cells exposed to DMBA + u.v. light. Second, along with the repair of DNA breaks, the insertion of additional breaks becomes evident leading to a massive breakdown of genomic DNA due to an endonucleolytic-like attack. And third, lethally affected cells rapidly lose their surface attachment. Because light induces damage in DNA when DMBA is present, it is likely that DMBA becomes closely associated with DNA. Thus, a starting point for mutagenic and carcinogenic action in the absence of light is suggested although activation of DMBA by a P-450 system does not appear to be a prerequisite of DMBA-DNA association. Still, DNA as such may not be the initial or the primary target for light-induced cell killing. In addition to interacting with DNA, DMBA is sequestered by membranes, suggesting that killing results from an oxygendependent release of catabolic enzymes. These enzymes, which may come from lysosomes, degrade DNA but concomitantly release surface-attached cells into the medium.
