States J Christopher, Reiners John J, Pounds Joel G, Kaplan David J, Beauerle Brian D, McNeely Samuel C, Mathieu Patricia, McCabe Michael J
Department of Pharmacology and Toxicology, University of Louisville, Louisville, KY 40202, USA.
Toxicol Appl Pharmacol. 2002 Apr 15;180(2):83-91. doi: 10.1006/taap.2002.9376.
Chronic ingestion of arsenite-contaminated drinking water causes skin, bladder, and liver cancer. The mechanism of arsenite-induced carcinogenesis is unknown. Arsenite is known to disrupt mitosis and to delay transit through M phase in normal diploid fibroblasts. SV40-transformed human fibroblasts were observed to be hypersensitive to the cytotoxic and cytostatic effects of NaAsO(2) compared with normal diploid fibroblasts in concentration-response experiments. Five to 20 microM NaAsO(2) induced cytostasis in cycling normal diploid fibroblasts but not overt lethality in quiescent normal diploid fibroblasts. High concentrations of arsenite were overtly lethal in both cycling and quiescent cells. The IC50 for cycling SV40-transformed fibroblasts was 3.8 and 4.8 microM for the SV40-transformed lines GM4429 and GM0637, respectively, whereas, in cycling normal diploid fibroblasts (GM0024), the IC50 was 24.7 microM. Microscopic examination of NaAsO(2)-treated SV40-transformed fibroblasts suggested a concentration-dependent accumulation of cells in mitosis undergoing apoptosis. Treatment of SV40-transformed fibroblasts with 0-10 microM NaAsO(2) caused a concentration-dependent inhibition of cell proliferation, accumulation of cells having G2/M DNA contents, and increases in the mitotic index. Phase microscopy, annexin V binding, and electron microscopy demonstrated that arrested mitotic cells underwent apoptosis. These results indicate that SV40-transformation sensitizes cells to arsenite-induced mitotic arrest and induction of apoptosis in the mitotic cells.
长期摄入受砷酸盐污染的饮用水会导致皮肤癌、膀胱癌和肝癌。砷酸盐诱发癌变的机制尚不清楚。已知砷酸盐会扰乱有丝分裂并延迟正常二倍体成纤维细胞通过M期的进程。在浓度-反应实验中，与正常二倍体成纤维细胞相比，观察到SV40转化的人成纤维细胞对NaAsO₂的细胞毒性和细胞生长抑制作用更为敏感。5至20 microM的NaAsO₂可诱导处于增殖周期的正常二倍体成纤维细胞生长停滞，但对静止的正常二倍体成纤维细胞不会造成明显的致死性。高浓度的砷酸盐对增殖周期和静止期的细胞均有明显的致死性。对于处于增殖周期的SV40转化成纤维细胞，GM4429和GM0637这两个SV40转化细胞系的半数抑制浓度（IC50）分别为3.8 microM和4.8 microM，而对于处于增殖周期的正常二倍体成纤维细胞（GM0024），IC50为24.7 microM。对经NaAsO₂处理的SV40转化成纤维细胞进行显微镜检查发现，有丝分裂期细胞出现浓度依赖性的凋亡聚集。用0至10 microM的NaAsO₂处理SV40转化成纤维细胞会导致细胞增殖受到浓度依赖性抑制、具有G2/M期DNA含量的细胞聚集以及有丝分裂指数增加。相差显微镜检查、膜联蛋白V结合检测和电子显微镜检查表明，停滞在有丝分裂期的细胞会发生凋亡。这些结果表明，SV40转化使细胞对砷酸盐诱导的有丝分裂停滞以及有丝分裂期细胞凋亡更为敏感。
