Carlisle D L, Pritchard D E, Singh J, Owens B M, Blankenship L J, Orenstein J M, Patierno S R
Department of Pharmacology, Molecular and Cellular Oncology and Genetics, The George Washington University Medical Center, Washington, DC 20037, USA.
Toxicol Sci. 2000 May;55(1):60-8. doi: 10.1093/toxsci/55.1.60.
Some forms of hexavalent chromium [Cr(VI)] are known to cause damage to respiratory tract tissue, and are thought to be human lung carcinogens. Because Cr(VI) is mutagenic and carcinogenic at doses that evoke cell toxicity, the objective of these experiments was to examine the effect of Cr(VI) on the growth, survival, and mode of cell death in normal human lung fibroblasts (HLF cells). DNA adduct formation was monitored as a marker for bioavailability of genotoxic chromium. We also examined the modulation of these endpoints by vitamins C and E. Long-term Cr(VI) exposures were employed, which decreased clonogenic cell survival by 25% to 95% in a dose-dependent manner. The predominant cellular response to Cr(VI) was growth arrest. We found that Cr(VI) caused up to 20% of HLF cells to undergo apoptosis, and documented apoptotic morphology and the phagocytosis of apoptotic bodies by neighboring cells. P53 levels increased 4- to 6-fold in chromium-treated cells. In contrast with previous studies using CHO cells, the present study using HLFs found that pretreatment with either vitamin C or E did not exhibit a significant effect on Cr-induced apoptosis or clonogenic survival. In addition, pretreatment with vitamin C did not affect the p53 induction observed after chromium treatment. Neither vitamin had any effect on Cr-DNA adduct formation. These data indicate that although pretreatment with vitamin C or E alters the spectrum of cellular and/or genetic lesions induced by chromium(VI), neither vitamin altered the initiation or progression of apoptosis in diploid human lung cells.
已知某些形式的六价铬[Cr(VI)]会对呼吸道组织造成损害，并且被认为是人类肺癌致癌物。由于Cr(VI)在引起细胞毒性的剂量下具有致突变性和致癌性，因此这些实验的目的是研究Cr(VI)对正常人肺成纤维细胞（HLF细胞）的生长、存活及细胞死亡方式的影响。监测DNA加合物的形成作为基因毒性铬生物利用度的标志物。我们还研究了维生素C和E对这些指标的调节作用。采用长期Cr(VI)暴露，其以剂量依赖性方式使克隆形成细胞存活率降低25%至95%。对Cr(VI)的主要细胞反应是生长停滞。我们发现Cr(VI)导致高达20%的HLF细胞发生凋亡，并记录了凋亡形态以及邻近细胞对凋亡小体的吞噬作用。在铬处理的细胞中，p53水平增加了4至6倍。与先前使用CHO细胞的研究不同，本研究使用HLF细胞发现，用维生素C或E预处理对Cr诱导的凋亡或克隆形成存活率均未表现出显著影响。此外，用维生素C预处理不影响铬处理后观察到的p53诱导。两种维生素对Cr-DNA加合物的形成均无任何影响。这些数据表明，尽管用维生素C或E预处理会改变由六价铬诱导的细胞和/或基因损伤谱，但两种维生素均未改变二倍体人肺细胞中凋亡的起始或进程。
