BACKGROUND: Estrogens play a central role in breast cancer development, and the estrogen receptor-alpha (ERalpha) remains the single most important predictor of breast cancer prognosis. Therefore, it is crucial to elucidate pathways that may contribute to ER signaling in clinical specimens. METHODS: Using extracts of fresh invasive ERalpha-positive invasive breast carcinomas, ductal carcinoma in situ, and normal glandular breast tissue, the authors performed Western blot analyses of the membrane-bound ER, 1 of its phosphorylated isoforms, and cytosolic fractions from the same specimens, examining associated proteins (Akt/mitogen-activated protein kinase pathways). Western blot analysis and immunocapture for the apoptosis and survival factors Bcl-2 agonist of death (BAD)/Bcl-2 and BAD/Bcl-xL were also performed. RESULTS: To the authors' knowledge, this is the first study to report that ERalpha was phosphorylated in the plasma membrane fractions derived from patients' invasive breast carcinomas. This was associated with a predominance of phosphorylated BAD and a relative reduction in Bcl-2 compared with both normal tissue and ductal carcinoma in situ, although such studies in fresh tissue did not corroborate these findings. The authors also demonstrated that the BAD/Bcl-2 and BAD/Bcl-xL complexes characterized the invasive carcinoma state. CONCLUSIONS: A phosphorylated form of the membrane ER was found to characterize the invasive cancer state. This was associated with a reduction in BAD/Bcl-2 and BAD/Bcl-xl. These data implicate the membrane ERalpha as the in vivo receptor responsible for transcription-independent cellular responses to estrogens. (c) 2008 American Cancer Society.
BACKGROUND: Estrogens play a central role in breast cancer development, and the estrogen receptor-alpha (ERalpha) remains the single most important predictor of breast cancer prognosis. Therefore, it is crucial to elucidate pathways that may contribute to ER signaling in clinical specimens. METHODS: Using extracts of fresh invasive ERalpha-positive invasive breast carcinomas, ductal carcinoma in situ, and normal glandular breast tissue, the authors performed Western blot analyses of the membrane-bound ER, 1 of its phosphorylated isoforms, and cytosolic fractions from the same specimens, examining associated proteins (Akt/mitogen-activated protein kinase pathways). Western blot analysis and immunocapture for the apoptosis and survival factors Bcl-2 agonist of death (BAD)/Bcl-2 and BAD/Bcl-xL were also performed. RESULTS: To the authors' knowledge, this is the first study to report that ERalpha was phosphorylated in the plasma membrane fractions derived from patients' invasive breast carcinomas. This was associated with a predominance of phosphorylated BAD and a relative reduction in Bcl-2 compared with both normal tissue and ductal carcinoma in situ, although such studies in fresh tissue did not corroborate these findings. The authors also demonstrated that the BAD/Bcl-2 and BAD/Bcl-xL complexes characterized the invasive carcinoma state. CONCLUSIONS: A phosphorylated form of the membrane ER was found to characterize the invasive cancer state. This was associated with a reduction in BAD/Bcl-2 and BAD/Bcl-xl. These data implicate the membrane ERalpha as the in vivo receptor responsible for transcription-independent cellular responses to estrogens. (c) 2008 American Cancer Society.
Authors: Mark A Feitelson; Alla Arzumanyan; Rob J Kulathinal; Stacy W Blain; Randall F Holcombe; Jamal Mahajna; Maria Marino; Maria L Martinez-Chantar; Roman Nawroth; Isidro Sanchez-Garcia; Dipali Sharma; Neeraj K Saxena; Neetu Singh; Panagiotis J Vlachostergios; Shanchun Guo; Kanya Honoki; Hiromasa Fujii; Alexandros G Georgakilas; Alan Bilsland; Amedeo Amedei; Elena Niccolai; Amr Amin; S Salman Ashraf; Chandra S Boosani; Gunjan Guha; Maria Rosa Ciriolo; Katia Aquilano; Sophie Chen; Sulma I Mohammed; Asfar S Azmi; Dipita Bhakta; Dorota Halicka; W Nicol Keith; Somaira Nowsheen Journal: Semin Cancer Biol Date: 2015-04-17 Impact factor: 15.707