Solhaug Anita, Øvrebø Steinar, Mollerup Steen, Låg Marit, Schwarze Per E, Nesnow Stephen, Holme Jørn A
Division of Environmental Medicine, Norwegian Institute of Public Health, PO Box 4404, Nydalen, N-0403 Oslo, Norway.
Chem Biol Interact. 2005 Jan 15;151(2):101-19. doi: 10.1016/j.cbi.2004.12.002.
Here we show that several cell signaling inhibitors have effect on cyp1a1 expression and the metabolism of benzo[a]pyrene (B[a]P) in Hepa1c1c7 cells. The CYP1A1 inhibitor alpha-naphthoflavone (alpha-NF), the p53 inhibitor pifithrin-alpha (PFT-alpha), the ERK inhibitors PD98059 and U0126, and the p38 MAPK inhibitors SB202190 and PD169316 induced the expression and level of cyp1a1 protein. On the other hand, during the first h the inhibitors appeared to reduce the metabolism of B[a]P as measured by the generation of tetrols and by covalent binding of B[a]P to macromolecules. In contrast, the phosphatidylinositol-3 (PI-3) kinase inhibitor wortmannin, had neither an effect on the cyp1a1 expression nor the B[a]P-metabolism. In order to avoid these unspecific effects, we characterized the mechanisms involved in the apoptotic effects of B[a]P-metabolites. B[a]P and the B[a]P-metabolites B[a]P-7,8-DHD and BPDE-I induced apoptosis, whereas B[a]P-4,5-DHD had no effect. B[a]P, B[a]P-7,8-DHD and BPDE-I induced an accumulation and phosphorylation of p53, while the Bcl-2 proteins Bcl-xl, Bad and Bid were down-regulated. Interestingly, the levels of anti-apoptotic phospho-Bad were up-regulated in response to B[a]P as well as to B[a]P-7,8-DHD and BPDE-I. Both p38 MAPK and JNK were activated, but the p38 MAPK inhibitors were not able to inhibit BPDE-I-induced apoptosis. PFT-alpha reduced the BPDE-I-induced apoptosis, while both the PI-3 kinase inhibitor and the ERK inhibitors increased the apoptosis in combination with BPDE-I. BPDE-I also triggered apoptosis in primary cultures of rat lung cells. In conclusion, often used cell signaling inhibitors both enhanced the expression and the level of cyp1a1 and more directly acted as inhibitors of cyp1a1 metabolism of B[a]P. However, studies with the B[a]P-metabolite BPDE-I supported the previous suggestion that p53 has a role in the pro-apoptotic signaling pathway induced by B[a]P. Furthermore, these studies also show that the reactive metabolites of B[a]P induce the anti-apoptotic signals, Akt and ERK. Neither the induction nor the activity of p38 MAPK and JNK seems to be of major importance for the B[a]P-induced apoptosis.
在此我们表明，几种细胞信号抑制剂对Hepa1c1c7细胞中cyp1a1的表达及苯并[a]芘（B[a]P）的代谢有影响。CYP1A1抑制剂α-萘黄酮（α-NF）、p53抑制剂pifithrin-α（PFT-α）、ERK抑制剂PD98059和U0126，以及p38丝裂原活化蛋白激酶（MAPK）抑制剂SB202190和PD169316可诱导cyp1a1蛋白的表达及水平升高。另一方面，在最初的1小时内，这些抑制剂似乎会降低B[a]P的代谢，这可通过四醇的生成以及B[a]P与大分子的共价结合来衡量。相比之下，磷脂酰肌醇-3（PI-3）激酶抑制剂渥曼青霉素对cyp1a1的表达及B[a]P的代谢均无影响。为避免这些非特异性影响，我们对B[a]P代谢产物的凋亡效应所涉及的机制进行了表征。B[a]P及B[a]P代谢产物B[a]P - 7,8 - DHD和BPDE - I可诱导细胞凋亡，而B[a]P - 4,5 - DHD则无此作用。B[a]P、B[a]P - 7,8 - DHD和BPDE - I可诱导p53的积累及磷酸化，而Bcl - 2蛋白Bcl - xl、Bad和Bid的表达则下调。有趣的是，抗凋亡磷酸化Bad水平在B[a]P以及B[a]P - 7,8 - DHD和BPDE - I作用下均上调。p38 MAPK和JNK均被激活，但p38 MAPK抑制剂无法抑制BPDE - I诱导的细胞凋亡。PFT - α可降低BPDE - I诱导的细胞凋亡，而PI - 3激酶抑制剂和ERK抑制剂与BPDE - I联合使用时均可增加细胞凋亡。BPDE - I还可在大鼠肺细胞原代培养物中引发细胞凋亡。总之，常用的细胞信号抑制剂既能增强cyp1a1的表达及水平，又能更直接地作为B[a]P的cyp1a1代谢抑制剂。然而，对B[a]P代谢产物BPDE - I的研究支持了之前有关p53在B[a]P诱导的促凋亡信号通路中起作用的观点。此外，这些研究还表明，B[a]P的活性代谢产物可诱导抗凋亡信号Akt和ERK。p38 MAPK和JNK的诱导及活性似乎对B[a]P诱导的细胞凋亡均无重要影响。
J Nutr Biochem. 2012-8-11
J Toxicol Environ Health A. 2012
Syst Biol Reprod Med. 2010-4
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