KLF17 attenuates estrogen receptor α-mediated signaling by impeding ERα function on chromatin and determines response to endocrine therapy

Publication date: Available online 21 April 2016
Source:Biochimica et Biophysica Acta (BBA) - Gene Regulatory Mechanisms
Author(s): Amjad Ali, Irina Ielciu, Huda Mohammad Alkreathy, Abid Ali Khan
Luminal-like breast cancer expressing estrogen receptor α (ERα) is among aggressive breast tumor subtypes and show poor prognosis. KLF17 play key role in breast cancer inhibition. However, the underlying mechanisms by which KLF17 control breast cancer progression remains unknown. Here, we show that KLF17 antagonizes ERα-dependent signaling to suppress breast cancer progression. KLF17 alters ERα-binding pattern throughout the genome and co-localizes with ERα on chromatin. Mechanistically, KLF17 forms a complex with ERα that interferes with ERα binding on chromatin and thereby attenuates ERα-dependent pathway. KLF17 increases the methylation status of ERE target promoters by recruiting transcriptional corepressor N-CoR/HDAC1 complex and prevents RNA polymerase II binding to suppress ERα-dependent transcriptional activation. Importantly, KLF17 preoccupy a subset of ERE target gene promoters and inhibits interaction of ERα with chromatin. Conversely, estrogen signaling suppresses KLF17 transcription via ERα/HDAC1-dependent mechanism. KLF17 expression negatively correlates with ERα target genes in multiple breast cancer samples. Enhanced KLF17 expression sensitizes ERα-positive breast cancer cells to endocrine therapy. KLF17 expression is downregulated in luminal breast cancer subtypes and is associated with poor survival rates in breast cancer patients. Taken together, these results indicate that KLF17-ERα interaction plays potential role in inhibition of ERα-dependent breast cancer progression and suggest an improved strategy for treatment of ERα-positive breast cancer patients.

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