Grillo C A, Dulout F N
Centro de Investigaciones en Genética Básica y Aplicada (CIGEBA), Facultad de Ciencias Veterinarias, Universidad Nacional de La Plata, Argentina.
Mutat Res. 1997 Apr 14;375(1):83-9. doi: 10.1016/s0027-5107(96)00256-4.
The effect of butylated hydroxytoluene (BHT) on chromosomal damage induced by bleomycin (BLM) in CHO cells was studied. Treatments were performed in cells at quiescent state (90/95% at G0-G1), 2 h after subculture (G1) or 3 h before fixation (G2). Cells were treated for 20 min with BLM plus BHT and subsequently incubated in the presence of BHT until fixation. Results were compared with those obtained from untreated and DMSO-treated controls, from treatments with BLM or BHT alone, from treatments with BLM followed by treatment with DMSO until fixation, and from treatments with BLM plus BHT for 20 min without post-treatment with BHT. BLM induced chromatid- and chromosome-type aberrations in cells treated at G0/G1 or G1 and chromatid-type aberrations in cells treated at the G2 stage. Post-treatment with BHT strongly decreased the frequency of chromosome- but not of chromatid-type aberrations in G0/G1 and G1 and of chromatid-type aberrations in G2. These results are explained assuming that chromosome-type aberrations induced at G0/G1 and G1, and chromatid-type aberrations induced at G2 are originated by the induction of double-strand breaks by BLM through the formation of free radicals. Thus, the observed effect of BHT post-treatment could be considered as evidence that chromosome aberrations are induced by BLM following a two-step mechanism. On the other hand, it is necessary to differentiate between chromatid-type aberrations induced by BLM at G0/G1 and those produced by G2 treatment on the basis of replication errors for the former and DNA repair errors for the latter. In addition, the induction of chromatid-type aberrations by BHT itself at G0/G1 must be taken into account. As BHT acts as an S-dependent agent, chromatid-type aberrations observed after treatment with BLM and BHT in G0/G1 could arise from single-strand breaks induced by BLM and DNA primary lesions induced by BHT.
研究了丁基羟基甲苯（BHT）对博来霉素（BLM）诱导的中国仓鼠卵巢（CHO）细胞染色体损伤的影响。处理在处于静止状态（G0-G1期占90/95%）、传代培养后2小时（G1期）或固定前3小时（G2期）的细胞中进行。细胞用BLM加BHT处理20分钟，随后在BHT存在下孵育直至固定。将结果与未处理和二甲基亚砜（DMSO）处理的对照、单独用BLM或BHT处理、先用BLM处理再用DMSO处理直至固定以及用BLM加BHT处理20分钟后不进行BHT后处理所获得的结果进行比较。BLM在G0/G1期或G1期处理的细胞中诱导了染色单体型和染色体型畸变，在G2期处理的细胞中诱导了染色单体型畸变。在G0/G1期和G1期用BHT后处理强烈降低了染色体型畸变的频率，但未降低染色单体型畸变的频率，在G2期降低了染色单体型畸变的频率。假设在G0/G1期和G1期诱导的染色体型畸变以及在G2期诱导的染色单体型畸变是由BLM通过自由基形成诱导双链断裂所致，这些结果就可以得到解释。因此，观察到的BHT后处理的效果可被视为证据，表明染色体畸变是由BLM通过两步机制诱导的。另一方面，有必要根据前者的复制错误和后者的DNA修复错误，区分BLM在G0/G1期诱导的染色单体型畸变和G2期处理产生的染色单体型畸变。此外，必须考虑BHT本身在G0/G1期诱导的染色单体型畸变。由于BHT作为一种依赖于S期的试剂，在G0/G1期用BLM和BHT处理后观察到的染色单体型畸变可能源于BLM诱导的单链断裂和BHT诱导的DNA原发性损伤。
