Aryl hydrocarbon (Ah) nonresponsiveness in estrogen receptor-negative MDA-MB-231 cells is associated with expression of a variant arnt protein.
Aryl hydrocarbon (Ah) nonresponsiveness in estrogen receptor-negative MDA-MB-231 cells is associated with expression of a variant arnt protein.
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DOI：
10.1006/abbi.1997.0289
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发表时间：
1997-10
影响因子：
3.9
通讯作者：
C. Wilson;J. Thomsen;D. Hoivik;M. Wormke;L. Stanker;C. Holtzapple;S. Safe
中科院分区：
文献类型：
--
作者：
C. Wilson;J. Thomsen;D. Hoivik;M. Wormke;L. Stanker;C. Holtzapple;S. Safe
一些研究报道了人类乳腺癌细胞株雌激素受体(ER)的表达与芳香烃(AH)反应性之间的相关性。MDA-MB-231细胞是ER阴性和AH无反应的细胞；然而，初步研究表明，在瞬时转染AH反应质粒的高传代(HP，>；50代)细胞中，2，3，7，8-四氯二苯并对二恶英诱导的CYP1A1 mRNA水平(5.8倍)和氯霉素乙酰转移酶活性(2.6倍)。相反，在低传代(LP)中没有观察到诱导反应，在HP细胞中AH受体的表达增加了2倍。进一步分析表明，在LP、MDA-MB-231和ah反应型人HepG2细胞中，ah受体mRNA转录本和免疫反应蛋白的表观分子量是相似的。相反，对ah受体核转运体(ARNT)蛋白的RT-PCR分析表明，HepG2细胞表达预期的2.6kb转录本，而在MDA-MB-231细胞中主要表达1.3kb转录本。Western印迹分析证实，HepG2细胞主要表达97 kDa的野生型Arnt，而在MDA-MB-231细胞中主要表达36 kDa的突变体。对ARNT变异形式的完整序列分析显示，该蛋白的C-末端区域(AA 330至789)存在主要缺失。与HepG2细胞一样，野生型2.6kb转录本在ER阳性的MCF-7细胞中被检测到，而低分子量变异体ARNT在ER阴性的MDA-MB-231、MDA-MB-435和阿霉素耐药的MCF-7细胞中占主导地位。这些结果表明，该蛋白的表达可能有助于乳腺癌的预后因素。
Several studies have reported a correlation between expression of the estrogen receptor (ER) and aryl hydrocarbon (Ah) responsiveness in human breast cancer cell lines. MDA-MB-231 cells are ER-negative and Ah-nonresponsive; however, initial studies showed that 2,3,7,8-tetrachlorodibenzo-p-dioxin induced CYP1A1 mRNA levels (5.8-fold) and chloramphenicol acetyltransferase activity (2.6-fold) in high passage (Hp, >50 passages) cells transiently transfected with an Ah-responsive plasmid. In contrast, no induction responses were observed in low passage (Lp, 2-fold increased expression of the Ah receptor in Hp cells. Further analysis revealed that the apparent molecular weight of the Ah receptor mRNA transcript and immunoreactive protein were comparable in Lp MDA-MB-231 and Ah-responsive human HepG2 cells. In contrast, RT-PCR analysis of the Ah receptor nuclear translocator (Arnt) protein showed that HepG2 cells expressed the expected 2.6-kb transcript, whereas a 1.3-kb transcript was the major product in MDA-MB-231 cells. Western blot analysis confirmed that HepG2 cells primarily expressed a 97-kDa wild-type form of Arnt, whereas a dominant 36-kDa variant was expressed in MDA-MB-231 cells. Complete sequence analysis of the variant form of Arnt revealed a major deletion of the C-terminal region of the protein (aa 330 to 789). Like HepG2 cells, the wild-type 2.6-kb transcript was detected in ER-positive (Ah-responsive) MCF-7 cells, whereas the low-molecular-weight variant Arnt was dominant in ER-negative MDA-MB-231, MDA-MB-435, and Adriamycin-resistant MCF-7 cells. These results suggest that expression of this protein may be useful as a prognostic factor in breast cancer.