GPCR48/LGR4 promotes tumorigenesis of prostate cancer via PI3K/Akt signaling pathway

G-protein-coupled receptor (GPCR) 48, also known as leucine-rich repeat-containing G-protein-coupled receptor (LGR) 4, is an orphan receptor belonging to the GPCR superfamily, which plays an important role in the development of various organs and multiple cancers. However, the function of GPCR48/LGR4 in prostate cancer has not been fully investigated. Herein, GPCR48/LGR4 was overexpressed and silenced in prostate cancer cells via plasmid and shRNA transfection, respectively. The expression of GPCR48/LGR4 in mRNA and protein levels was analyzed using RT-qPCR and Western blotting, respectively. Subsequently, we demonstrated the effects of GPCR48/LGR4 on the migration, invasion, proliferation and apoptosis of prostate cancer cells, including Du145 and PC-3 cells. Next, we investigated the relationship between GPCR48/LGR4 and phosphatidylinositol-4,5-bisphosphate 3-kinase (PI3K)/Akt signaling pathway. The results showed that the overexpression of GPCR48/LGR4 was associated with the up-regulation of Akt, a key effector of PI3K/Akt signaling pathway, which meantime up-regulated the expression of mammalian target of rapamycin (mTOR) and glycogen synthase kinase 3β (GSK-3β), while down-regulated forkhead box, class O (FOXO), all of whom are the downstream targets of PI3K/Akt signaling pathway. Hence, the results suggested that GPCR48/LGR4 may regulate prostate cancer cells and tumor growth via the PI3K/Akt signaling pathway and could provide a better therapeutic target for the diagnosis and treatment of prostate cancer.

[1]  M. Brattain,et al.  Dual inhibitors of PI3K/mTOR or mTOR-selective inhibitors: which way shall we go? , 2011, Current medicinal chemistry.

[2]  J. Nelson.  Endothelin inhibition: novel therapy for prostate cancer. , 2003, The Journal of urology.

[3]  Jiri Polivka,et al.  Molecular targets for cancer therapy in the PI3K/AKT/mTOR pathway. , 2014, Pharmacology & therapeutics.

[4]  M. Gershengorn,et al.  Synergistic activation of the androgen receptor by bombesin and low-dose androgen. , 2002, Clinical cancer research : an official journal of the American Association for Cancer Research.

[5]  D. Sabatini,et al.  mTOR Signaling in Growth Control and Disease , 2012, Cell.

[6]  B. Zhong,et al.  Regulation of Akt-dependent cell survival by Syk and Rac. , 2003, Blood.

[7]  A. Hsueh,et al.  Characterization of two LGR genes homologous to gonadotropin and thyrotropin receptors with extracellular leucine-rich repeats and a G protein-coupled, seven-transmembrane region. , 1998, Molecular endocrinology.

[8]  M. Ebert,et al.  LGR4 and LGR6 are differentially expressed and of putative tumor biological significance in gastric carcinoma , 2012, Virchows Archiv.

[9]  W. Skarnes,et al.  Defective postnatal development of the male reproductive tract in LGR4 knockout mice. , 2006, Developmental biology.

[10]  K. Itoh,et al.  Target molecules in specific immunotherapy against prostate cancer , 2003, International Journal of Clinical Oncology.

[11]  Xiangshan Fan,et al.  Expression of Lgr5 in human colorectal carcinogenesis and its potential correlation with β-catenin , 2010, International Journal of Colorectal Disease.

[12]  H. Kung,et al.  Neuropeptide-Induced Androgen Independence in Prostate Cancer Cells: Roles of Nonreceptor Tyrosine Kinases Etk/Bmx, Src, and Focal Adhesion Kinase , 2001, Molecular and Cellular Biology.

[13]  P. Casey,et al.  Androgen Receptor Activation by Gs Signaling in Prostate Cancer Cells* , 2005, Journal of Biological Chemistry.

[14]  高橋 秀和.  Significance of Lgr5[+ve] cancer stem cells in the colon and rectum , 2012 .

[15]  Dali Li,et al.  Lgr4 is a key regulator of prostate development and prostate stem cell differentiation , 2013, Stem cells.

[16]  K. Yamamura,et al.  Defective development of the gall bladder and cystic duct in Lgr4‐ hypomorphic mice , 2009, Developmental dynamics : an official publication of the American Association of Anatomists.

[17]  Yan Xie,et al.  Vasoactive Intestinal Peptide Transactivates the Androgen Receptor through a Protein Kinase A-Dependent Extracellular Signal-Regulated Kinase Pathway in Prostate Cancer LNCaP Cells , 2007, Molecular Pharmacology.

[18]  Hwee Tong Tan,et al.  Identification of key players for colorectal cancer metastasis by iTRAQ quantitative proteomics profiling of isogenic SW480 and SW620 cell lines. , 2011, Journal of proteome research.

[19]  J. Gutkind,et al.  G-protein-coupled receptors and cancer , 2007, Nature Reviews Cancer.

[20]  Y. Daaka.  G Proteins in Cancer: The Prostate Cancer Paradigm , 2004, Science's STKE.

[21]  K. Tikoo,et al.  Regulation of MDA-MB-231 cell proliferation by GSK-3β involves epigenetic modifications under high glucose conditions. , 2014, Experimental cell research.

[22]  Enrique Casado,et al.  PI3K/Akt signalling pathway and cancer. , 2004, Cancer treatment reviews.

[23]  A. Tenesa,et al.  New insights into the aetiology of colorectal cancer from genome-wide association studies , 2009, Nature Reviews Genetics.

[24]  A. Hsueh,et al.  The nematode leucine-rich repeat-containing, G protein-coupled receptor (LGR) protein homologous to vertebrate gonadotropin and thyrotropin receptors is constitutively active in mammalian cells. , 2000, Molecular endocrinology.

[25]  Dali Li,et al.  Deletion of G protein-coupled receptor 48 leads to ocular anterior segment dysgenesis (ASD) through down-regulation of Pitx2 , 2008, Proceedings of the National Academy of Sciences.

[26]  Yuquan Wei,et al.  GPR48, a poor prognostic factor, promotes tumor metastasis and activates β-catenin/TCF signaling in colorectal cancer. , 2013, Carcinogenesis.

[27]  Jian Luo,et al.  Regulation of bone formation and remodeling by G-protein-coupled receptor 48 , 2009, Development.

[28]  Lopamudra Giri,et al.  The structure of dynamic GPCR signaling networks , 2014, Wiley interdisciplinary reviews. Systems biology and medicine.

[29]  M. Kitagawa,et al.  Up-regulation of GPR48 induced by down-regulation of p27Kip1 enhances carcinoma cell invasiveness and metastasis. , 2006, Cancer research.

[30]  Yongchun Zhu,et al.  GPR48 promotes multiple cancer cell proliferation via activation of Wnt signaling. , 2013, Asian Pacific journal of cancer prevention : APJCP.

[31]  J. Growcott.  Preclinical anticancer activity of the specific endothelin A receptor antagonist ZD4054 , 2009, Anti-cancer drugs.