期刊名称：Proceedings of the National Academy of Sciences
印刷版ISSN：0027-8424
电子版ISSN：1091-6490
出版年度：2014
卷号：111
期号：38
页码：E3957-E3965
DOI：10.1073/pnas.1404221111
语种：English
出版社：The National Academy of Sciences of the United States of America
摘要：SignificanceThis work unveils a previously unidentified function of the tumor suppressor pleckstrin homology domain leucine-rich repeat protein phosphatase (PHLPP) in inhibiting oncogenic signaling by suppressing the steady-state levels of receptor tyrosine kinases such as the EGF receptor. Specifically, PHLPP modifies the histone code to control the transcription of receptor tyrosine kinases. This epigenetic function can account for the upregulation of receptor tyrosine kinases in the multiple cancer types where PHLPP function is compromised. Growth factor receptor levels are aberrantly high in diverse cancers, driving the proliferation and survival of tumor cells. Understanding the molecular basis for this aberrant elevation has profound clinical implications. Here we show that the pleckstrin homology domain leucine-rich repeat protein phosphatase (PHLPP) suppresses receptor tyrosine kinase (RTK) signaling output by a previously unidentified epigenetic mechanism unrelated to its previously described function as the hydrophobic motif phosphatase for the protein kinase AKT, protein kinase C, and S6 kinase. Specifically, we show that nuclear-localized PHLPP suppresses histone phosphorylation and acetylation, in turn suppressing the transcription of diverse growth factor receptors, including the EGF receptor. These data uncover a much broader role for PHLPP in regulation of growth factor signaling beyond its direct inactivation of AKT: By suppressing RTK levels, PHLPP dampens the downstream signaling output of two major oncogenic pathways, the PI3 kinase/AKT and the Rat sarcoma (RAS)/ERK pathways. Our data are consistent with a model in which PHLPP modifies the histone code to control the transcription of RTKs.
