Wohak Laura E, Baranski Ann-Christin, Krais Annette M, Schmeiser Heinz H, Phillips David H, Arlt Volker M
Department of Analytical, Environmental and Forensic Sciences, MRC-PHE Centre for Environment and Health, King's College London, London, UK.
Section of Molecular Carcinogenesis, Institute of Cancer Research, Sutton, Surrey, UK.
Mutagenesis. 2018 Oct 11;33(4):311-321. doi: 10.1093/mutage/gey025.
The tumour suppressor p53, encoded by TP53, is a key player in a wide network of signalling pathways. We investigated its role in the bioactivation of the environmental carcinogen 3-nitrobenzanthrone (3-NBA)found in diesel exhaust and its metabolites 3-aminobenzanthrone (3-ABA) and N-hydroxy-3-aminobenzanthrone (N-OH-3-ABA) in a panel of isogenic human colorectal HCT116 cells differing only with respect to their TP53 status [i.e. TP53(+/+), TP53(+/-), TP53(-/-), TP53(R248W/+) or TP53(R248W/-)]. As a measure of metabolic competence, DNA adduct formation was determined using 32P-postlabelling. Wild-type (WT) p53 did not affect the bioactivation of 3-NBA; no difference in DNA adduct formation was observed in TP53(+/+), TP53(+/-) and TP53(-/-) cells. Bioactivation of both metabolites 3-ABA and N-OH-3-ABA on the other hand was WT-TP53 dependent. Lower 3-ABA- and N-OH-3-ABA-DNA adduct levels were found in TP53(+/-) and TP53(-/-) cells compared to TP53(+/+) cells, and p53's impact was attributed to differences in cytochrome P450 (CYP) 1A1 expression for 3-ABA whereas for N-OH-3-ABA, an impact of this tumour suppressor on sulphotransferase (SULT) 1A1/3 expression was detected. Mutant R248W-p53 protein function was similar to or exceeded the ability of WT-p53 in activating 3-NBA and its metabolites, measured as DNA adducts. However, identification of the xenobiotic-metabolising enzyme(s) (XMEs), through which mutant-p53 regulates these responses, proved difficult to decipher. For example, although both mutant cell lines exhibited higher CYP1A1 induction after 3-NBA treatment compared to TP53(+/+) cells, 3-NBA-derived DNA adduct levels were only higher in TP53(R248W/-) cells but not in TP53(R248W/+) cells. Our results show that p53's influence on carcinogen activation depends on the agent studied and thereby on the XMEs that mediate the bioactivation of that particular compound. The phenomenon of p53 regulating CYP1A1 expression in human cells is consistent with other recent findings; however, this is the first study highlighting the impact of p53 on sulphotransferase-mediated (i.e. SULT1A1) carcinogen metabolism in human cells.
由TP53基因编码的肿瘤抑制蛋白p53是广泛信号通路网络中的关键因子。我们研究了其在环境致癌物3-硝基苯并蒽酮（3-NBA）生物活化中的作用，3-NBA存在于柴油尾气中，其代谢产物为3-氨基苯并蒽酮（3-ABA）和N-羟基-3-氨基苯并蒽酮（N-OH-3-ABA）。我们使用了一组同基因的人结肠HCT116细胞进行研究，这些细胞仅在TP53状态上有所不同[即TP53(+/+)、TP53(+/-)、TP53(-/-)、TP53(R248W/+)或TP53(R248W/-)]。作为代谢能力的衡量指标，使用32P后标记法测定DNA加合物的形成。野生型（WT）p53不影响3-NBA的生物活化；在TP53(+/+)、TP53(+/-)和TP53(-/-)细胞中未观察到DNA加合物形成的差异。另一方面，两种代谢产物3-ABA和N-OH-3-ABA的生物活化是依赖于WT-TP53的。与TP53(+/+)细胞相比，在TP53(+/-)和TP53(-/-)细胞中发现较低的3-ABA-和N-OH-3-ABA-DNA加合物水平，p53的影响归因于3-ABA的细胞色素P450（CYP）1A1表达差异，而对于N-OH-3-ABA，检测到该肿瘤抑制因子对磺基转移酶（SULT）1A1/3表达的影响。以DNA加合物衡量，突变型R248W-p53蛋白在激活3-NBA及其代谢产物方面的功能与WT-p53相似或更强。然而，很难破译突变型p53通过哪些异生物质代谢酶（XMEs）来调节这些反应。例如，尽管与TP53(+/+)细胞相比，两种突变细胞系在3-NBA处理后均表现出更高的CYP1A1诱导，但仅在TP53(R248W/-)细胞中3-NBA衍生的DNA加合物水平更高，而在TP53(R248W/+)细胞中并非如此。我们的结果表明，p53对致癌物激活的影响取决于所研究的物质，从而取决于介导该特定化合物生物活化的XMEs。p53在人类细胞中调节CYP1A1表达的现象与其他近期研究结果一致；然而，这是第一项强调p53对人类细胞中磺基转移酶介导（即SULT1A1）的致癌物代谢影响的研究。
