Estradiol up-regulates antiapoptotic Bcl-2 messenger ribonucleic acid and protein in tumorigenic ovarian surface epithelium cells
Estradiol up-regulates antiapoptotic Bcl-2 messenger ribonucleic acid and protein in tumorigenic ovarian surface epithelium cells
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DOI：
10.1210/en.142.6.2351
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发表时间：
2001-06-01
期刊：
影响因子：
4.8
通讯作者：
Leung, PCK
中科院分区：
文献类型：
--
作者：
Choi, KC;Kang, SK;Leung, PCK
大多数上皮性卵巢肿瘤似乎起源于卵巢表面上皮（OSE）。尽管雌激素可能与卵巢肿瘤发生有关，但雌激素在肿瘤性OSE细胞凋亡调控中的确切作用仍不确定。永生化OSE（IOSE）细胞系由人正常OSE产生。这些细胞系代表了人正常OSE的早期肿瘤（IOSE-29）、致瘤性（IOSE-29 EC）和晚期肿瘤（IOSE-29 EC/T4和IOSE-29 EC/T5）转化阶段。目前的研究表明，雌激素受体（ER）α和β的mRNA和蛋白质在IOSE细胞系中表达。在正常OSE和IOSE-29细胞中没有观察到差异，而用17 β-雌二醇（E-2; 10（-8）-10（-6）M）处理导致IOSE-29 EC细胞中每个培养物的胸苷掺入和DNA含量增加。雌激素拮抗剂他莫昔芬（10（-6）M）处理后，E-2的这种作用减弱，表明E-2的作用是通过特异性ER介导的。在第6天之前，对胸苷掺入无刺激作用，但停药6天后，胸苷掺入显著增加。因为胸苷掺入的DNA含量每文化的比例没有改变，这种E-2的影响似乎并不表示刺激增殖，而是抑制细胞凋亡。此外，他莫昔芬（10-6 M）处理诱导IOSE-29 EC细胞凋亡高达3倍，而E-2（10（-8）-10（-6）M）加他莫昔芬以剂量依赖性方式减弱他莫昔芬诱导的凋亡。在IOSE细胞系中，促凋亡bar和抗凋亡bcl-2在mRNA和蛋白水平上均表达。有趣的是，用E-2处理导致bcl-2 mRNA和蛋白水平的显著增加（分别为2倍和1.7倍），而在bar mRNA水平上没有观察到差异。因此，E-2可能通过上调bcl-2来增强IOSE-29 EC的存活，并且抗凋亡bcl-2可能是这些细胞中凋亡途径的主导调节剂。总之，本研究表明早期肿瘤（IOSE-29）、致瘤（IOSE-29 EC）和晚期肿瘤（IOSE-29 EC/T4和T5）OSE细胞在mRNA和蛋白质水平同时表达ER α和ER β。此外，E-2通过ER阻止他莫昔芬诱导的细胞凋亡。E-2的作用机制可能与bcl-2基因在mRNA和蛋白水平上的上调有关。这些结果表明，雌激素可能通过阻止致瘤OSE细胞凋亡在卵巢肿瘤发生中发挥作用。
Most epithelial ovarian tumors appear to arise from the ovarian surface epithelium (OSE). Even though it has been suggested that estrogen may be associated with ovarian tumorigenesis, the exact role of estrogen in the regulation of apoptosis in neoplastic OSE cells remains uncertain. Immortalized OSE (IOSE) cell lines were generated from human normal OSE. These cell lines represent early neoplastic (IOSE-29), tumorigenic (IOSE-29EC), and late neoplastic (IOSE-29EC/T4 and IOSE-29EC/T5) transformation stages from human normal OSE. The present studies demonstrated that both mRNAs and proteins of estrogen receptor (ER) alpha and beta were expressed in IOSE cell lines. No difference was observed in normal OSE and IOSE-29 cells, whereas treatment with 17 beta -estradiol (E-2; 10(-8)-10(-6) M) resulted in an increased thymidine incorporation and DNA content per culture in IOSE-29EC cells. This effect of E-2 was attenuated with tamoxifen treatment ( 10(-6) M), the estrogen antagonist, suggesting that the effect of E-2 is mediated through specific ERs. There was no stimulatory effect on thymidine incorporation before day 6, but after 6 days off, treatment, thymidine incorporation was significantly increased. Because the ratio of thymidine incorporation to DNA content per culture did not change, this E-2 effect does not appear to indicate stimulation of proliferation but, rather, inhibition of apoptosis. In addition, treatment with tamoxifen (10-6 M) induced apoptosis up to 3-fold in IOSE-29EC cells, whereas cotreatment with E-2 (10(-8)-10(-6) M)plus tamoxifen attenuated tamoxifen-induced apoptosis in a dose-dependent manner. Both proapoptotic bar and antiapoptotic bcl-2 at messenger RNA (mRNA) and protein levels were expressed in IOSE cell lines. Interestingly, treatments with E-2 resulted in a significant increase of bcl-2 mRNA and protein levels (2- and 1.7-fold, respectively), whereas no difference was observed in bar mRNA level. Thus, E-2 may enhance survival of IOSE-29EC by up-regulating bcl-2, and antiapoptotic bcl-2 may be a dominant regulator of apoptotic pathway in these cells. In conclusion, the present study indicates that early neoplastic (IOSE-29), tumorigenic (IOSE-29EC), and late neoplastic (IOSE-29EC/T4 and T5) OSE cells expressed both ER alpha and ER beta at the mRNA and protein levels. In addition, E-2 prevented tamoxifen induced-apoptosis through ERs. The mechanism of E-2 action may be associated with up-regulation of bcl-2 gene at mRNA and protein levels. These results suggest that estrogen may play a role in ovarian tumorigenesis by preventing apoptosis in tumorigenic OSE cells.