Madia Federica, Giordano Gennaro, Fattori Vittorio, Vitalone Annabella, Branchi Igor, Capone Francesca, Costa Lucio G
Department of Pharmacology of Natural Substances and General Physiology, University of Rome La Sapienza, Italy.
Toxicol Lett. 2004 Dec 1;154(1-2):11-21. doi: 10.1016/j.toxlet.2004.06.013.
Polybrominated diphenyl ethers (PBDEs) are an important class of flame retardants. Because of their presence in maternal milk and their structural similarity to polychlorinated biphenyls (PCBs), concern has been raised on their possible developmental neurotoxicity. Aim of the present study was to investigate the in vitro effects of PBDE-99 (2,2', 4,4', 5-pentabromodiphenyl ether) on astroglial cells (human 132-1N1 astrocytoma cells) and comparing it with those of the PCB mixture Aroclor 1254. Both PBDE-99 and Aroclor 1254 caused a concentration-dependent inhibition of MTT (3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyltetrazolium bromide) reduction, however, only the latter increased lactate dehydrogenase (LDH) release or cell death, assessed by the trypan blue assay. PBDE-99 caused translocation of the three protein kinase C (PKC) isozymes (alpha, epsilon, zeta) present in 132-1N1 astrocytoma cells, while Aroclor 1254 affected only PKCalpha and epsilon translocation. However, pre-incubation with the PKC inhibitor GF109203X or PKC down-regulation by the phorbol ester PMA, had minimal or no effect on PBDE-99 or Aroclor 1254-induced cytotoxicity. Similarly, the calcium chelator BAPTA-AM, the tyrosine kinase inhibitor genistein, and the MEK (mitogen activated protein kinase kinase) inhibitor PD98059 had no effect on PBDE-99 and Aroclor 1254 cytoxicity. On the other hand, the phosphatidylinositol 3 kinase (PI-3K) inhibitor LY290042 enhanced PBDE-99 toxicity, but did not affect Aroclor 1254. Because of the involvement of PI-3K in apoptotic cell death, the ability of PBDE-99 and Aroclor 1254 to induce apoptosis in astrocytoma cells was investigated. PBDE-99, but not Aroclor 1254, caused apoptotic cell death in astrocytoma cells, assessed by the TUNEL method and by Hoechst 33258 staining, via a p53 dependent mechanism. These results suggest that PBDE-99 and Aroclor 1254 exert differential cytotoxic effects on human astroglial cells.
多溴二苯醚（PBDEs）是一类重要的阻燃剂。由于它们存在于母乳中，且结构与多氯联苯（PCBs）相似，人们对其可能的发育神经毒性表示担忧。本研究的目的是调查PBDE - 99（2,2',4,4',5 - 五溴二苯醚）对星形胶质细胞（人132 - 1N1星形细胞瘤细胞）的体外影响，并将其与多氯联苯混合物Aroclor 1254的影响进行比较。PBDE - 99和Aroclor 1254均引起了MTT（3 - [4,5 - 二甲基噻唑 - 2 - 基] - 2,5 - 二苯基四氮唑溴盐）还原的浓度依赖性抑制，然而，只有后者增加了乳酸脱氢酶（LDH）释放或细胞死亡，这通过台盼蓝试验进行评估。PBDE - 99导致了132 - 1N1星形细胞瘤细胞中存在的三种蛋白激酶C（PKC）同工酶（α、ε、ζ）的易位，而Aroclor 1254仅影响PKCα和ε的易位。然而，用PKC抑制剂GF109203X预孵育或用佛波酯PMA下调PKC，对PBDE - 99或Aroclor 1254诱导的细胞毒性影响极小或没有影响。同样，钙螯合剂BAPTA - AM、酪氨酸激酶抑制剂染料木黄酮和MEK（丝裂原活化蛋白激酶激酶）抑制剂PD98059对PBDE - 99和Aroclor 1254的细胞毒性没有影响。另一方面，磷脂酰肌醇3激酶（PI - 3K）抑制剂LY290042增强了PBDE - 99的毒性，但不影响Aroclor 1254。由于PI - 3K参与凋亡性细胞死亡，因此研究了PBDE - 99和Aroclor 1254诱导星形细胞瘤细胞凋亡的能力。通过TUNEL法和Hoechst 33258染色评估，PBDE - 99而非Aroclor 1254通过p53依赖性机制导致星形细胞瘤细胞发生凋亡性细胞死亡。这些结果表明，PBDE - 99和Aroclor 1254对人星形胶质细胞具有不同的细胞毒性作用。
