Department of Biology, Howard University, Washington DC 20059, USA.
Environ Int. 2010 Nov;36(8):893-900. doi: 10.1016/j.envint.2010.06.010. Epub 2010 Aug 17.
An understanding of congener specific cellular absorption of PCBs is important to the study of the organ specific body burden of an individual and to their toxic effects. We have previously demonstrated that single PCB congeners induce cytotoxicity, as evidenced by decreased cellular viability and accelerated apoptotic death. There is very little, if any, information available on the differences in toxicity due to the nature of absorption of PCBs in different cells. To obtain such information human liver (HepG2) cells (in medium with 10% FBS) were exposed to 70 μM of both PCB-153 (non-coplanar hexachlorobiphenyl) and PCB-77 (coplanar tetrachlorobiphenyl), and human kidney (HK2) cells in serum free medium were exposed to 80 and 40 μM of PCB-153 and PCB-77 respectively, according to their LC(50) values in these cells. Medium and cells were collected separately at each time interval from 30 min to 48 h, and PCB concentrations were analyzed in both by GC-MS using biphenyl as an internal standard following hexane:acetone (50:50) extraction. We also performed trypan blue exclusion, DNA fragmentation and fluorescence microscopic studies in assessing cell viability and apoptotic cell death. About 40% of PCB-153 (35 μM, 50% of the maximum value) was detected in HepG2 cells within 30 min, and it reached its highest concentration at 6h (60 μM), concomitant with the PCB depletion in the medium (5 μM). For PCB-77, the highest concentrations within the cells were reached at 3h. However, the absorption levels of PCB-153 and PCB-77 in HK2 cells reached their peaks at 3 and 6h respectively. Exposure of human liver and kidney cells to PCB-153 and PCB-77 caused accelerated apoptotic cell death in a time-dependent manner. The studies demonstrated that (1) liver cells initiate the absorption of PCBs much faster than kidney cells; however, the concentration reaches its maximum level much earlier in kidney cells; (2) both PCB-153 and PCB-77 induced enhanced apoptotic death in liver and kidney cells; and (3) kidney cells are more vulnerable to PCBs based on the results of apoptosis and cellular viability, even with almost similar absorption or tissue burden of PCBs.
了解同系物特异性细胞对 PCB 的吸收对于研究个体器官特异性体内负荷和其毒性作用非常重要。我们之前已经证明，单一 PCB 同系物会诱导细胞毒性，这表现在细胞活力下降和加速细胞凋亡死亡。关于由于不同细胞对 PCB 吸收的性质而导致的毒性差异，几乎没有信息。为了获得此类信息，用 70μM 的 PCB-153（非共平面六氯联苯）和 PCB-77（共平面四氯联苯）处理人肝（HepG2）细胞（在含有 10%FBS 的培养基中），用人肾（HK2）细胞在无血清培养基中分别暴露于 80μM 和 40μM 的 PCB-153 和 PCB-77，根据它们在这些细胞中的 LC50 值。在 30 分钟至 48 小时的每个时间间隔，分别从培养基和细胞中收集 PCB 浓度，并通过 GC-MS 用联苯作为内标，在正己烷：丙酮（50:50）萃取后进行分析。我们还进行了台盼蓝排斥、DNA 片段化和荧光显微镜研究，以评估细胞活力和凋亡细胞死亡。在 HepG2 细胞中，30 分钟内检测到约 40%的 PCB-153（35μM，最高值的 50%），6 小时时达到最高浓度（60μM），同时培养基中的 PCB 耗尽（5μM）。对于 PCB-77，细胞内的最高浓度出现在 3 小时。然而，PCB-153 和 PCB-77 在 HK2 细胞中的吸收水平分别在 3 小时和 6 小时达到峰值。人肝和肾细胞暴露于 PCB-153 和 PCB-77 会导致细胞凋亡死亡加速，呈时间依赖性。研究表明：（1）肝细胞比肾细胞更快地启动 PCB 的吸收；然而，在肾细胞中，浓度达到最高水平的时间更早；（2）PCB-153 和 PCB-77 均诱导肝和肾细胞中增强的凋亡死亡；（3）基于凋亡和细胞活力的结果，肾细胞对 PCBs 更为敏感，即使 PCBs 的吸收或组织负荷几乎相似。
