Chromatinized Protein Kinase C-θ Directly Regulates Inducible Genes in Epithelial to Mesenchymal Transition and Breast Cancer Stem Cells

Abstract

Epithelial to mesenchymal transition (EMT) is activated during cancer invasion and metastasis, enriches for cancer stem cells (CSCs), and contributes to therapeutic resistance and disease recurrence. Signal transduction kinases play a pivotal role as chromatin-anchored proteins in eukaryotes. Here we report for the first time that protein kinase C-theta (PKC-θ) promotes EMT by acting as a critical chromatin-anchored switch for inducible genes via transforming growth factor β (TGF-β) and the key inflammatory regulatory protein NF-κB. Chromatinized PKC-θ exists as an active transcription complex and is required to establish a permissive chromatin state at signature EMT genes. Genome-wide analysis identifies a unique cohort of inducible PKC-θ-sensitive genes that are directly tethered to PKC-θ in the mesenchymal state. Collectively, we show that cross talk between signaling kinases and chromatin is critical for eliciting inducible transcriptional programs that drive mesenchymal differentiation and CSC formation, providing novel mechanisms to target using epigenetic therapy in breast cancer.

SUPPLEMENTAL MATERIAL

Supplemental material for this article may be found at http://dx.doi.org/10.1128/MCB.01693-13.

ACKNOWLEDGMENTS

We thank Elissa Sutcliffe for optimization of the ChIP library protocol in the Rao Lab. We acknowledge Harpreet Vohra and Michael Devoy for extensive support on the FACS experiments detailed in this study. We thank Cathy Gillespie and Reena Ghildyal for their help with microscopy. We also acknowledge Chris Parish for allowing us to utilize his laboratory facilities and for discussions on the project during the early phase of this work. We also thank Pek Siew Lim for critical reading of the manuscript.

We thank the support of Endeavor Postgraduate Award granted to Anjum Zafar (641_2008) and the University of Canberra PDF fellowship scheme.