BACKGROUND/AIMS: The expression of estrogen receptor-α (ERα) is one of the most important diagnostic and prognostic factors of breast cancer. Recently, ERα-36 has been identified as a novel variant of ER-α. ERα-36 lacks intrinsic transcription activity and mainly mediates non-genomic estrogen signaling. The noncanonical IKK family member IKKε is essential for regulating antiviral signaling pathways and is recently discovered as a breast cancer oncogene. IKKε interacts with and phosphorylates ERα on serine 167, induces ERα transactivation activity and enhances ERα binding to DNA in ER-positive breast cancer cells. However, the correlation between IKKε and the ERα-36 signaling pathway in ER-negative breast cancer cells remains unclear. METHODS AND RESULTS: In this study, we show that IKKε interacts with ERα-36 and increases its expression in breast cancer cells. As shown by western blot assays, the upregulation of ERα-36 by IKKε was significant. In MDA-MB-231 cells which are ER-negative, IKKε was able to increase the expression of ERα-36 in a dose-dependent manner, and the RNA interference assay indicated the correlation between IKKε and ERα-36 expression. Moreover, IKKε enhanced the growth of MDA-MB-231 and MDA-MB-436 cells. CONCLUSIONS: These results suggest that IKKε increases ERα-36 expression and is involved in ERα-36 mediated non-genomic estrogen signaling.
BACKGROUND/AIMS: The expression of estrogen receptor-α (ERα) is one of the most important diagnostic and prognostic factors of breast cancer. Recently, ERα-36 has been identified as a novel variant of ER-α. ERα-36 lacks intrinsic transcription activity and mainly mediates non-genomic estrogen signaling. The noncanonical IKK family member IKKε is essential for regulating antiviral signaling pathways and is recently discovered as a breast cancer oncogene. IKKε interacts with and phosphorylates ERα on serine 167, induces ERα transactivation activity and enhances ERα binding to DNA in ER-positive breast cancer cells. However, the correlation between IKKε and the ERα-36 signaling pathway in ER-negative breast cancer cells remains unclear. METHODS AND RESULTS: In this study, we show that IKKε interacts with ERα-36 and increases its expression in breast cancer cells. As shown by western blot assays, the upregulation of ERα-36 by IKKε was significant. In MDA-MB-231 cells which are ER-negative, IKKε was able to increase the expression of ERα-36 in a dose-dependent manner, and the RNA interference assay indicated the correlation between IKKε and ERα-36 expression. Moreover, IKKε enhanced the growth of MDA-MB-231 and MDA-MB-436 cells. CONCLUSIONS: These results suggest that IKKε increases ERα-36 expression and is involved in ERα-36 mediated non-genomic estrogen signaling.
Authors: D Bauer; N Redmon; E Mazzio; E Taka; J S Reuben; A Day; S Sadrud-Din; H Flores-Rozas; K F A Soliman; S Darling-Reed Journal: Cytokine Date: 2015-06-20 Impact factor: 3.861
Authors: Jian Zhang; Jianwei Ren; Jiamin Wei; Charing C N Chong; Dongjie Yang; Yulong He; George G Chen; Paul B S Lai Journal: BMC Cancer Date: 2016-11-30 Impact factor: 4.430