Schaefer E L, Selkirk J K
Cancer Res. 1985 Aug;45(8):3487-92.
Four mouse hepatoma cell lines, a parent (Hepa-1c1c7) and three variants (MUL12, BPrc1, and TAOc1BPrc1) which had been derived from Hepa-1c1c7 by the fluorescence-activated cell sorter, were incubated with benzo(a)pyrene, and the metabolites were analyzed by high-pressure liquid chromatography. Among these four cell lines, Hepa-1c1c7 and MUL12 metabolized benzo(a)pyrene the most quickly and to the greatest extent, and BPrc1 had the weakest metabolic activity for this substrate. TAOc1BPrc1 had intermediate benzo(a)pyrene-metabolizing activity, depending on cell density and incubation time. At low cell density, the active variant TAOc1Bprc1 resembled the weakly active Bprc1 in accumulating a low amount of ethyl acetate-soluble metabolites in the medium while, at high cell density, TAOc1Bprc1 resembled the parent clone Hepa-1c1c7 and the highly active variant MUL12. At short incubation times, TAOc1Bprc1 also had low conjugating activity while, at longer incubation times, the conjugating activity approached that of Hepa-1c1c7 and MUL12. At low cell density, Bprc1 was able to produce phenols, but this variant did not seem to have this ability at high cell density. When the substrate concentration was 4 microM and the incubation time was 24 h, beta-glucuronidase treatment of water-soluble metabolites released about 5.3 times more pmol of quinones compared with phenols. But when the substrate concentration was 25 nM, beta-glucuronidase released about 2.0 times as many phenols compared with quinones. The parent and the two more actively metabolizing variants showed differences in the peak times of accumulation of 9,10-diol and 7,8-diol of benzo(a)pyrene, which may have implications for binding to DNA and nuclear proteins. It was concluded that BPrc1 has basal but not easily inducible aryl hydrocarbon hydroxylase activity, whereas Hepa-1c1c7, MUL12, and TAOc1Bprc1 have basal and inducible aryl hydrocarbon hydroxylase activity. These results show that variants of a single parent cell line can exhibit significant differences in the rate and extent of metabolism of benzo(a)pyrene.
四种小鼠肝癌细胞系，一种亲本细胞系（Hepa - 1c1c7）和三种通过荧光激活细胞分选仪从Hepa - 1c1c7衍生而来的变体细胞系（MUL12、BPrc1和TAOc1BPrc1），与苯并(a)芘一起孵育，其代谢产物通过高压液相色谱进行分析。在这四种细胞系中，Hepa - 1c1c7和MUL12代谢苯并(a)芘的速度最快且程度最大，而BPrc1对该底物的代谢活性最弱。TAOc1BPrc1具有中等的苯并(a)芘代谢活性，这取决于细胞密度和孵育时间。在低细胞密度下，活性变体TAOc1Bprc1在培养基中积累少量乙酸乙酯可溶代谢产物的情况与弱活性的Bprc1相似，而在高细胞密度下，TAOc1Bprc1与亲本克隆Hepa - 1c1c7和高活性变体MUL12相似。在短孵育时间时，TAOc1Bprc1的结合活性也较低，而在较长孵育时间时，其结合活性接近Hepa - 1c1c7和MUL12。在低细胞密度下，Bprc1能够产生酚类，但该变体在高细胞密度下似乎没有这种能力。当底物浓度为4 microM且孵育时间为24小时时，对水溶性代谢产物进行β - 葡萄糖醛酸酶处理后，释放的醌类的皮摩尔数比酚类多约5.3倍。但当底物浓度为25 nM时，β - 葡萄糖醛酸酶释放的酚类比醌类多约2.0倍。亲本细胞系和另外两种代谢更活跃的变体细胞系在苯并(a)芘的9,10 - 二醇和7,8 - 二醇积累的峰值时间上存在差异，这可能对与DNA和核蛋白的结合有影响。得出的结论是，BPrc1具有基础但不易诱导的芳烃羟化酶活性，而Hepa - 1c1c7、MUL12和TAOc1Bprc1具有基础且可诱导的芳烃羟化酶活性。这些结果表明，单一亲本细胞系的变体在苯并(a)芘代谢的速率和程度上可表现出显著差异。
