探討雌激素代謝物影響乳癌細胞惡化之機轉

2-hydroxyestradiol 和 4-hydroxyestradiol是屬於鄰苯二酚類(catechol)，為雌激素的主要代謝產物。在惡性的乳癌細胞Hs578T中，會因為兩者的代謝累積造成自由基的產生，進而透過自由基影響基質金屬蛋白水解酶(MMPs)的活化。並在癌細胞轉移的過程中扮演重要角色。其中，對於遺傳物質產生毒性，造成DNA各種傷害，會以DNA的斷裂、形成穩定的鍵結物(stable adducts) 和去嘌呤化產物( depurinating adducts)來呈現。本篇研究以酶譜法（Zymography assay）及侵襲轉移法（Invasion/Migration assay）分析證實雌激素的代謝物會活化Hs578T乳癌細胞株的侵襲轉移能力是透過活化基質金屬蛋白酶2（matrix metalloproteinase-2, MMP-2）的活性。在蛋白質免疫染色分析（Immumoblot assay）中發現，處理過的乳癌細胞Hs578T會明顯地活化PI3K/p-Akt訊息調控路徑，並導致下游的GSK-3β和β-catenin蛋白的過度表現。更進一步探討，細胞經4-OHE2和2-OHE2處理之後，會因為產生ROS而造成DNA受損，以致於明顯降低DNA正確的接合效率。相對的，在正常乳房細胞株HBL-100則並無受到明顯地影響。這些的結果顯示，4-OHE2和2-OHE2會造成乳房腫瘤細胞更加惡化，是透過DNA修復系統的功能異常，導致癌細胞惡性增生及侵襲轉移。

Catechol estrogens, the oxidative metabolites of estrogen, have been reported to be associated with the development of breast cancer. However, their effects on cell turmorigenesis of breast are underestimated. To this end, the present study is aiming at understanding the molecular mechanism of catechol metabolites in exposing of 2-Hydroxyestradiol (2-OHE2) and 4-Hydroxyestradiol (4-OHE2) on Hs578T cells increase matrix metalloproteinase 2 (MMP-2), and contribute to cells with aggressive phenotypes of invasiveness and migration. In immunoblotting assay, PI3K/Akt signaling pathway is activated in 2-OHE2 and 4-OHE2treated Hs578T cells. Furthermore, lower efficiency of precise non-homologous end joining (NHEJ) activity was found in Hs578T cells, but not in HBL-100 cell line after treatment of 2-OHE2 and 4-OHE2 .These findings provide the support that catechol metabolites, 2-OHE2 and 4-OHE2, may cause malignant breast cancer, including cells proliferation, invasion, migration and effected DNA repair system.