GRK3 is a direct target of CREB activation and regulates neuroendocrine differentiation of prostate cancer cells
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Meixiang Sang1,7,*, Mohit Hulsurkar1,5,*, Xiaochong Zhang1,7,*, Haiping Song1,8, Dayong Zheng1,9, Yan Zhang1,10, Min Li2, Jianming Xu3, Songlin Zhang2, Michael Ittmann4, Wenliang Li1,5,6
1Texas Therapeutics Institute, Brown Foundation Institute of Molecular Medicine, University of Texas Health Science Center at Houston, Houston, TX, USA
2Department of Pathology and Laboratory Medicine, University of Texas Health Science Center at Houston, Houston, TX, USA
3Department of Molecular and Cell Biology, Baylor College of Medicine, Houston, TX, USA
4Department of Pathology and Immunology, Baylor College of Medicine, and Michael E. DeBakey VAMC, Houston, TX, USA
5Graduate School of Biomedical Sciences, University of Texas Health Science Center at Houston, Houston, TX, USA
6Division of Oncology, Department of Internal Medicine, and Memorial Herman Cancer Center, University of Texas Health Science Center at Houston, Houston, TX, USA
7Tumor Research Institute, the Fourth Hospital of Hebei Medical University, Shijiazhuang, China
8Breast and Thyroid surgery center, The Union Hospital of Tongji Medical College, Huazhong University of science and technology, Wuhan, China
9Department of Medical Oncology, Nanfang Hospital, Southern Medical University, Guangzhou, China
10The Union Hospital of Tongji Medical College, Huazhong University of science and technology, Wuhan, China
*These authors have contributed equally to this work
Wenliang Li, email: firstname.lastname@example.org
Keywords: GRK3, CREB, androgen deprivation therapy, neuroendocrine prostate cancer
Received: September 22, 2015 Accepted: April 23, 2016 Published: May 14, 2016
Neuroendocrine prostate cancer (NEPC) is an aggressive subtype of prostate cancer that commonly arises through neuroendocrine differentiation (NED) of prostate adenocarcinoma (PAC) after therapy, such as radiation therapy and androgen deprivation treatment (ADT). No effective therapeutic is available for NEPC and its molecular mechanisms remain poorly understood. We have reported that G protein-coupled receptor kinase 3 (GRK3, also called ADRBK2) promotes prostate cancer progression. In this study, we demonstrate that the ADT-activated cAMP response element binding protein (CREB) directly targets and induces GRK3. We show GRK3 expression is higher in NEPC than in PAC cells and mouse models, and it positively correlates with the expression and activity of CREB in human prostate cancers. Notably, overexpression of GRK3 in PAC cells increased the expression of NE markers in a kinase activity dependent manner. Conversely, silencing GRK3 blocked CREB-induced NED in PAC cells, reversed NE phenotypes and inhibited proliferation of NEPC cells. Taken together, these results indicate that GRK3 is a new critical activator of NE phenotypes and mediator of CREB activation in promoting NED of prostate cancer cells.
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