ACK1/TNK2 Regulates Histone H4 Tyr88-phosphorylation and AR Gene Expression in Castration-Resistant Prostate Cancer

Publication date: 12 June 2017
Source:Cancer Cell, Volume 31, Issue 6
Author(s): Kiran Mahajan, Pavani Malla, Harshani R. Lawrence, Zhihua Chen, Chandan Kumar-Sinha, Rohit Malik, Sudhanshu Shukla, Jongphil Kim, Domenico Coppola, Nicholas J. Lawrence, Nupam P. Mahajan
The androgen receptor (AR) is critical for the progression of prostate cancer to a castration-resistant (CRPC) state. AR antagonists are ineffective due to their inability to repress the expression of AR or its splice variant, AR-V7. Here, we report that the tyrosine kinase ACK1 (TNK2) phosphorylates histone H4 at tyrosine 88 upstream of the AR transcription start site. The WDR5/MLL2 complex reads the H4-Y88-phosphorylation marks and deposits the transcriptionally activating H3K4-trimethyl marks promoting AR transcription. Reversal of the pY88-H4 epigenetic marks by the ACK1 inhibitor (R)-9bMS-sensitized naive and enzalutamide-resistant prostate cancer cells and reduced AR and AR-V7 levels to mitigate CRPC tumor growth. Thus, a feedforward ACK1/pY88-H4/WDR5/MLL2/AR epigenetic circuit drives CRPC and is necessary for maintenance of the malignant state.

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Mahajan et al. report that ACK1 phosphorylates histone H4 at Y88 upstream of the AR transcription start site, leading to the WDR5/MLL2 complex-mediated increase of AR transcription. Inhibition of ACK1 reverses the pY88-H4 marks and reduces AR and AR-V7 levels to mitigate castration-resistant prostate tumor growth.


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