scholarly journals Targeting Orphan G Protein-Coupled Receptor 17 with T0 Ligand Impairs Glioblastoma Growth

Cancers ◽  
2021 ◽  
Vol 13 (15) ◽  
pp. 3773
Author(s):  
Phuong Doan ◽  
Phung Nguyen ◽  
Akshaya Murugesan ◽  
Kumar Subramanian ◽  
Saravanan Konda Konda Mani ◽  
...  

Glioblastoma, an invasive high-grade brain cancer, exhibits numerous treatment challenges. Amongst the current therapies, targeting functional receptors and active signaling pathways were found to be a potential approach for treating GBM. We exploited the role of endogenous expression of GPR17, a G protein-coupled receptor (GPCR), with agonist GA-T0 in the survival and treatment of GBM. RNA sequencing was performed to understand the association of GPR17 expression with LGG and GBM. RT-PCR and immunoblotting were performed to confirm the endogenous expression of GPR17 mRNA and its encoded protein. Biological functions of GPR17 in the GBM cells was assessed by in vitro analysis. HPLC and histopathology in wild mice and an acute-toxicity analysis in a patient-derived xenograft model were performed to understand the clinical implication of GA-T0 targeting GPR17. We observed the upregulation of GPR17 in association with improved survival of LGG and GBM, confirming it as a predictive biomarker. GA-T0-stimulated GPR17 leads to the inhibition of cyclic AMP and calcium flux. GPR17 signaling activation enhances cytotoxicity against GBM cells and, in patient tissue-derived mesenchymal subtype GBM cells, induces apoptosis and prevents proliferation by stoppage of the cell cycle at the G1 phase. Modulation of the key genes involved in DNA damage, cell cycle arrest, and in several signaling pathways, including MAPK/ERK, PI3K–Akt, STAT, and NF-κB, prevents tumor regression. In vivo activation of GPR17 by GA-T0 reduces the tumor volume, uncovering the potential of GA-T0–GPR17 as a targeted therapy for GBM treatment. Conclusion: Our analysis suggests that GA-T0 targeting the GPR17 receptor presents a novel therapy for treating glioblastoma.

Author(s):  
Layla Van Doren ◽  
Nga Nguyen ◽  
Christopher Garzia ◽  
Elizabeth Fletcher ◽  
Ryan Stevenson ◽  
...  

Objective: 12-LOX (12-lipoxygenase) produces a number of bioactive lipids including 12(S)-HETE that are involved in inflammation and platelet reactivity. The GPR31 (G-protein–coupled receptor 31) is the proposed receptor of 12(S)-HETE; however, it is not known whether the 12(S)-HETE-GPR31 signaling axis serves to enhance or inhibit platelet activity. Approach and Results: Using pepducin technology and biochemical approaches, we provide evidence that 12(S)-HETE-GPR31 signals through Gi to enhance PAR (protease-activated receptor)-4–mediated platelet activation and arterial thrombosis using both human platelets and mouse carotid artery injury models. 12(S)-HETE suppressed AC (adenylyl cyclase) activity through GPR31 and resulted in Rap1 and p38 activation and low but detectable calcium flux but did not induce platelet aggregation. A GPR31 third intracellular (i3) loop–derived pepducin, GPR310 (G-protein–coupled receptor 310), significantly inhibited platelet aggregation in response to thrombin, collagen, and PAR4 agonist, AYPGKF, in human and mouse platelets but relative sparing of PAR1 agonist SFLLRN in human platelets. GPR310 treatment gave a highly significant 80% protection ( P =0.0018) against ferric chloride–induced carotid artery injury in mice by extending occlusion time, without any effect on tail bleeding. PAR4-mediated dense granule secretion and calcium flux were both attenuated by GPR310. Consistent with these results, GPR310 inhibited 12(S)-HETE–mediated and PAR4-mediated Rap1-GTP and RASA3 translocation to the plasma membrane and attenuated PAR4-Akt and ERK activation. GPR310 caused a right shift in thrombin-mediated human platelet aggregation, comparable to the effects of inhibition of the Gi-coupled P2Y 12 receptor. Co-immunoprecipitation studies revealed that GPR31 and PAR4 form a heterodimeric complex in recombinant systems. Conclusions: The 12-LOX product 12(S)-HETE stimulates GPR31-Gi–signaling pathways, which enhance thrombin-PAR4 platelet activation and arterial thrombosis in human platelets and mouse models. Suppression of this bioactive lipid pathway, as exemplified by a GPR31 pepducin antagonist, may provide beneficial protective effects against platelet aggregation and arterial thrombosis with minimal effect on hemostasis.


2018 ◽  
Vol 104 (5) ◽  
pp. 330-337 ◽  
Author(s):  
Li-qian Zhang ◽  
Su-qing Yang ◽  
Xiang-dong Qu ◽  
Xian-jun Chen ◽  
Hong-sheng Lu ◽  
...  

Purpose: Ovarian cancer is one of the leading causes of death for women worldwide. The present study aims to investigate the role of G protein-coupled receptor 137 (GPR137) in the biological activities of ovarian cancer cells. Methods: (QUERY: Please supply Methods for Abstract) Results: G protein-coupled receptor 137 was highly expressed in clinical ovarian cancer tissues and exhibited the highest protein levels in SKOV3 cells and OVCAR3 cells. Knockdown of GPR137 caused significant decreases in cell proliferative rates and colony formation abilities in SKOV3 cells and OVCAR3 cells and also inhibited the in vivo tumorigenesis in a xenograft model. It was observed that knockdown of GPR137 inhibited cell motility by up to 40% in SKOV3 cells and approximately 65% in OVCAR3 cells in wound-healing assay. Cell migration abilities were consistently inhibited by 68.2% in SKOV3 cells and 59.3% in OVCAR3 cells, whereas cell invasion abilities were inhibited by 64.0% and 74.2% in SKOV3 and OVCAR3 cells, respectively, after knockdown of GPR137. When GPR137 was depleted, epithelial markers were increased, while mesenchymal markers decreased. Conclusions: Our data suggest that GPR137 plays pro-oncogenic roles in ovarian cancer via regulation of the PI3K/AKT pathway. These observations might pave new insights into therapeutic strategies against human ovarian cancer.


2009 ◽  
Vol 83 (16) ◽  
pp. 8141-8152 ◽  
Author(s):  
Joseph D. Sherrill ◽  
Melissa P. Stropes ◽  
Olivia D. Schneider ◽  
Diana E. Koch ◽  
Fabiola M. Bittencourt ◽  
...  

ABSTRACT The presence of numerous G protein-coupled receptor (GPCR) homologs within the herpesvirus genomes suggests an essential role for these genes in viral replication in the infected host. Such is the case for murine cytomegalovirus (MCMV), where deletion of the M33 GPCR or replacement of M33 with a signaling defective mutant has been shown to severely attenuate replication in vivo. In the present study we utilized a genetically altered version of M33 (termed R131A) in combination with pharmacological inhibitors to further characterize the mechanisms by which M33 activates downstream signaling pathways. This R131A mutant of M33 fails to support salivary gland replication in vivo and, as such, is an important tool that can be used to examine the signaling activities of M33. We show that M33 stimulates the transcription factor CREB via heterotrimeric Gq/11 proteins and not through promiscuous coupling of M33 to the Gs pathway. Using inhibitors of signaling molecules downstream of Gq/11, we demonstrate that M33 stimulates CREB transcriptional activity in a phospholipase C-β and protein kinase C (PKC)-dependent manner. Finally, utilizing wild-type and R131A versions of M33, we show that M33-mediated activation of other signaling nodes, including the mitogen-activated protein kinase family member p38α and transcription factor NF-κB, occurs in the absence of Gq/11 and PKC signaling. The results from the present study indicate that M33 utilizes multiple mechanisms to modulate intracellular signaling cascades and suggest that signaling through PLC-β and PKC plays a central role in MCMV pathogenesis in vivo.


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