Regulator Of G-protein Signaling 5 Expression Research Articles

RGS5 as a Biomarker of Pericytes, Involvement in Vascular Remodeling and Pulmonary Arterial Hypertension.

Pulmonary arterial hypertension (PAH) is a life-threatening disease characterized by a sustained rise in mean pulmonary artery pressure. Pulmonary vascular remodeling serves an important role in PAH. Identifying a key driver gene to regulate vascular remodeling of the pulmonary microvasculature is critical for PAH management. Differentially expressed genes were identified using the Gene Expression Omnibus (GEO) GSE117261, GSE48149, GSE113439, GSE53408 and GSE16947 datasets. A co-expression network was constructed using weighted gene co-expression network analysis. Novel and key signatures of PAH were screened using four algorithms, including weighted gene co-expression network analysis, GEO2R analysis, support vector machines recursive feature elimination and robust rank aggregation rank analysis. Regulator of G-protein signaling 5 (RGS5), a pro-apoptotic/anti-proliferative protein, which regulate arterial tone and blood pressure in vascular smooth muscle cells. The expression of RGS5 was determined using reverse transcription-quantitative PCR (RT-qPCR) in PAH and normal mice. The location of RGS5 and pericytes was detected using immunofluorescence. Compared with that in the normal group, RGS5 expression was upregulated in the PAH group based on GEO and RT-qPCR analyses. RGS5 expression in single cells was enriched in pericytes in single-cell RNA sequencing analysis. RGS5 co-localization with pericytes was detected in the pulmonary microvasculature of PAH. RGS5 regulates vascular remodeling of the pulmonary microvasculature and the occurrence of PAH through pericytes, which has provided novel ideas and strategies regarding the occurrence and innovative treatment of PAH.

RGS5-TGFβ-Smad2/3 axis switches pro- to anti-apoptotic signaling in tumor-residing pericytes, assisting tumor growth.

Regulator-of-G-protein-signaling-5 (RGS5), a pro-apoptotic/anti-proliferative protein, is a signature molecule of tumor-associated pericytes, highly expressed in several cancers, and is associated with tumor growth and poor prognosis. Surprisingly, despite the negative influence of intrinsic RGS5 expression on pericyte survival, RGS5highpericytes accumulate in progressively growing tumors. However, responsible factor(s) and altered-pathway(s) are yet to report. RGS5 binds with Gαi/q and promotes pericyte apoptosis in vitro, subsequently blocking GPCR-downstream PI3K-AKT signaling leading to Bcl2 downregulation and promotion of PUMA-p53-Bax-mediated mitochondrial damage. However, within tumor microenvironment (TME), TGFβ appeared to limit the cytocidal action of RGS5 in tumor-residing RGS5highpericytes. We observed that in the presence of high RGS5 concentrations, TGFβ-TGFβR interactions in the tumor-associated pericytes lead to the promotion of pSmad2-RGS5 binding and nuclear trafficking of RGS5, which coordinately suppressed RGS5-Gαi/q and pSmad2/3-Smad4 pairing. The RGS5-TGFβ-pSmad2 axis thus mitigates both RGS5- and TGFβ-dependent cellular apoptosis, resulting in sustained pericyte survival/expansion within the TME by rescuing PI3K-AKT signaling and preventing mitochondrial damage and caspase activation. This study reports a novel mechanism by which TGFβ fortifies and promotes survival of tumor pericytes by switching pro- to anti-apoptotic RGS5 signaling in TME. Understanding this altered RGS5 signaling might prove beneficial in designing future cancer therapy.

Usefulness of Tumor Tissue Biopsy for Predicting the Biological Behavior of Hepatocellular Carcinoma.

Assessment of the biological behavior of tumors is important for choosing an appropriate cancer therapy. In hepatocellular carcinoma (HCC), the biological behaviour can be assessed by tumor morphology and molecular biology. This study investigated the usefulness of tumor tissue biopsy for predicting the biological behavior of HCC. We studied 43 patients who underwent hepatectomy and preoperative liver tumor biopsy for HCC. We performed clinicopathological and immunohistochemical (IHC) analyses. The expression of the following molecules was examined: regulator of G-protein signaling 5 (RGS5), glypican-3 (GPC3), keratin 19 (K19), epithelial cell adhesion molecule (EpCAM), protein induced by vitamin K absence or antagonist-II (PIVKA-II), β-Catenin, and p53. There was an overall 83.7% agreement regarding tumor differentiation between the preoperative biopsy specimens and the resected specimens. The accuracy of IHC analysis was more than 70% for all molecules between the preoperative biopsy specimens and the resected specimens. The RGS5-positive biopsy cases had higher serum α-fetoprotein levels (p=0.04), a higher rate of moderately or poorly differentiated tumors (p=0.02) and portal vein invasion (p=0.0003) than the RGS5-negative biopsy cases. The GPC3-positive biopsy cases were younger (p=0.04), had higher serum PIVKA-II levels (p=0.01), and a higher rate of portal vein invasion (p=0.03) than the GPC3-negative biopsy cases. The PIVKA-II-positive biopsy cases had significantly higher serum PIVKA-II levels than the PIVKA-II-negative biopsy cases (p=0.02). The other molecular markers showed no significantly different clinical findings between the positive and negative cases. In HCC, there was a high agreement rate of both the histopathological and IHC findings between preoperative biopsy specimens and resected specimens. In the biopsy specimens of HCC, RGS5 and GPC3 expression were useful molecular makers for predicting portal vein invasion. Liver tumor biopsy is useful for predicting the biological behavior of HCC through histopathological and immunohistochemical findings.

Programmed death-ligand 1 expression is an unfavorable prognostic factor of hepatocellular carcinoma after archiving sustained virologic response for hepatitis C virus infection.

The aim of the present study was to study the pathological prognostic factor of initial hepatocellular carcinoma (HCC) after archiving sustained virologic response (SVR) for hepatitis C virus (HCV) infection. A single-center retrospective analysis was performed for patients who underwent hepatectomy between 2003 and 2017. We studied clinico-pathological findings of resected liver tissues in 35 patients with HCC after SVR treated by interferon (IFN group) and 13 patients with HCC after SVR treated by direct acting antivirals (DAA group). We also performed immunohistochemical staining using antibodies against programmed death-ligand 1 (PD-L1), cytokeratin 19, epithelial cell adhesion molecule (EpCAM) and regulator of G-protein signaling 5 (RGS5). PD-L1 positive HCC was observed in 6 cases of the IFN group and 4 cases of the DAA group. In the IFN group, in univariate analysis of recurrence free survival after surgery (RFS), the PD-L1 expression had a statistically significant impact (HR=6.01; P=0.02). In the multivariate analysis of RFS, PD-L1 expression significantly remained (HR=5.01; P=0.03). For both RFS and overall survival, Kaplan-Meier curves confirmed that patients with PD-L1 expression showed significantly worse prognosis (log-rank test P<0.01). Nuclear grade, RGS5 expression, and EpCAM expression were significantly higher in the PD-L1-positive HCC group compared with the PD-L1-negative HCC group (P<0.05). Therefore, PD-L1 expression may be an independent prognostic factor of surgically resected HCC after achieving SVR.

Parathyroid-Targeted Overexpression of Regulator of G-Protein Signaling 5 (RGS5) Causes Hyperparathyroidism in Transgenic Mice.

The relationship between impaired calcium sensing, dysregulated parathyroid hormone (PTH) secretion, and parathyroid cell proliferation in parathyroid neoplasia is not understood. We previously reported that a GTPase activating protein, regulator of G-protein signaling 5 (RGS5) is overexpressed in a subset of parathyroid tumors associated with primary hyperparathyroidism (PHPT) and that RGS5 can inhibit signaling from the calcium-sensing receptor (CASR). In vivo, we found that RGS5-null mice have abnormally low PTH levels. To gain a better understanding of the potential role of RGS5 overexpression in parathyroid neoplasia and PHPT and to investigate whether inhibition of CASR signaling can lead to parathyroid neoplasia, we created and characterized a transgenic mouse strain overexpressing RGS5 specifically in the parathyroid gland. These mice develop hyperparathyroidism, bone changes reflective of elevated PTH, and parathyroid neoplasia. Further, expression of exogenous RGS5 in normal human parathyroid cells results in impaired signaling from CASR and negative feedback on PTH secretion. These results provide evidence that RGS5 can modulate signaling from CASR and support a role for RGS5 in the pathogenesis of PHPT through inhibition of CASR signaling. © 2019 American Society for Bone and Mineral Research.

RGS5 decreases the proliferation of human ovarian carcinoma‑derived primary endothelial cells through the MAPK/ERK signaling pathway in hypoxia.

Regulator of G-protein signaling 5 (RGS5), a tissue-specific signal-regulating molecule, plays a key role in the development of the vasculature. It was recently found that RGS5 is abundantly expressed in epithelial ovarian cancer (EOC) compared with the normal ovaries. However, the distribution of RGS5 in EOC and its significance require further investigation. The aim of the present study was to investigate the expression of RGS5 in EOC, as well as its association with cancer differentiation, metastasis and clinicopathological parameters. Immunohistochemistry (IHC), western blotting, RT-PCR, wound-healing, cell proliferation and flow cytometric assays were the methods used in the present study. RGS5 was highly expressed in the cytoplasm of ovarian carcinoma cells and in microvascular structures. The expression of RGS5 in EOC was negatively associated with peritoneal metastasis (P=0.004), but it was not found to be associated with age, tumor size, clinical stage or lymph node metastasis (P>0.05). EOC patients with high RGS5 expression had a prolonged progression-free survival (72.34±8.41 vs. 43.56±5.41 months, P<0.001). High expression of RGS5 was correlated with significantly lower microvascular density (MVD) as indicated by the expression of CD34, whereas the opposite was observed in tissues with low RGS5 expression (P<0.05). Hypoxia increased RGS5 expression in ovarian carcinoma-derived endothelial cells (ODMECs), whereas the proliferative capacity of ODMECs exhibited a significant increase following RNAi-mediated reduction of RGS5 expression. These data indicated that RGS5 plays a key role in angiogenesis in ovarian carcinoma. In addition, RGS5 downregulated the expression of the downstream proteins CDC25A, CDK2 and cyclin E, which are mediated by the mitogen-activated protein kinase/extracellular signal-regulated kinase pathway, causing ODMEC arrest in the G1 phase of the cell cycle under hypoxic conditions. Collectively, our data indicated that RGS5 is crucial for the occurrence and development of ovarian cancer, and that RGS5 and its signaling pathway may serve as anti-angiogenesis targets for the treatment of ovarian cancer.

Regulator of G-protein signaling 5 enhances portal vein invasion in hepatocellular carcinoma.

Portal vein invasion (PVI) is a major prognostic factor in hepatocellular carcinoma (HCC). The aim of the present study was to identify molecules that regulate PVI. Sections of cancerous tissue, paired noncancerous tissue and the PVI area were collected from 3 frozen HCC sections, using laser microdissection. The present study focused on 3 upregulated molecules, integrin β3 (ITGB3), secreted phosphoprotein 1 (SPP1) and regulator of G-protein signaling 5 (RGS5), and 2 molecules that were downregulated in PVI tissue compared with cancer tissue, metallothionein 1G (MT1G) and metallothionein 1H (MT1H), as determined by cDNA microarray analysis. Reverse transcription-quantitative polymerase chain reaction analysis of 32 HCC cases revealed that RGS5 mRNA levels were significantly increased and MT1 G and MT1H mRNA levels were significantly decreased in cancerous tissue compared with noncancerous tissue. However, there was no significant difference in ITGB3 and SPP1 expression. There were no significant differences between the expression of these molecules and any clinicopathologic factors, including PVI. Immunohistochemical staining for RGS5 in 60 HCC cases demonstrated that RGS5 protein levels were higher in cancerous tissue compared with paired noncancerous tissue in 63.3% of HCC cases. Furthermore, high expression of RGS5 in cancerous tissue was significantly associated with PVI and tended to be associated with intrahepatic metastasis. Confluent multinodular type was significantly more frequent in cases with high expression of RGS5 in the cancerous tissue. Therefore, RGS5 may be a useful prognostic biomarker as well as a potential target of molecular therapy to treat HCC.

Regulator of G-Protein Signaling 5 Prevents Smooth Muscle Cell Proliferation and Attenuates Neointima Formation.

Regulator of G-protein signaling 5 (RGS5) is abundantly expressed in vascular smooth muscle cells (SMCs) and inhibits G-protein signaling by enhancing the guanosine triphosphate-hydrolyzing activity of Gα-subunits. In the present study, we investigated the effects of RGS5 on vascular SMC function in vitro and neointima formation after wire-induced injury in mice and determined the underlying mechanisms. We found a robust expression of RGS5 in native arteries of C57BL/6 mice and a highly significant downregulation within neointimal lesions 10 and 21 days after vascular injury as assessed by quantitative polymerase chain reaction, immunoblotting, and immunohistochemistry. In vitro, RGS5 was found significantly downregulated after mitogenic stimulation of human coronary artery SMCs. To restore RGS5 levels, SMCs were transduced with adenoviral vectors encoding wild-type RGS5 or a nondegradable mutant. RGS5-WT and, even more prominently, the C2A-RGS5 mutant prevented SMC proliferation and migration. In contrast, the siRNA-mediated knockdown of RGS5 significantly augmented SMC proliferation. Following overexpression of RGS5, fluorescence-activated cell sorting analysis of propidium iodide-stained cells indicated cell cycle arrest in G0/G1 phase. Mechanistically, inhibition of the phosphorylation of the extracellular signal-regulated kinase 1/2 and mitogen-activated protein kinase downstream signaling was shown to be responsible for the anti-proliferative effect of RGS5. Following wire-induced injury of the femoral artery in C57BL/6 mice, adenoviral-mediated overexpression of RGS5-WT or C2A-RGS5 significantly reduced SMC proliferation and neointima formation in vivo. Downregulation of RGS5 is an important prerequisite for SMC proliferation in vitro and in vivo. Therefore, reconstitution of RGS5 levels represents a promising therapeutic option to prevent vascular remodeling processes.

Abstract 17947: Regulator of G-Protein Signaling 5 Prevents Smooth Muscle Cell Proliferation and Attenuates Neointima Formation

Introduction: Regulator of G-protein signaling 5 (RGS5) is abundantly and specifically expressed in vascular smooth muscle cells (SMCs) and inhibits G-protein signaling by enhancing the GTP-hydrolyzing activity of Gα-subunits. Hypothesis: In the present study, we aimed to investigate the effects of RGS5 on vascular SMC function in vitro and neointima formation in vivo and to determine the underlying molecular mechanisms. Methods: Expression of RGS5 was assessed in vitro and in vivo by qPCR, immunoblotting and immunohistochemistry. Proliferation and migration of human coronary artery SMC were assessed in vitro following the adenoviral-mediated over expression of wild type (WT) RGS5, of a non-degradable mutant (C2A-RGS5) or siRNA-mediated knock down. In vivo, the proliferation and neointima formation were assessed in a wire-mediated injury model of the femoral artery in C57BL/6J mice. Results: We found a robust expression of RGS5 in native arteries of C57BL/6 mice and a significant down-regulation within neointimal lesions 10 and 21 days after vascular injury as assessed by qPCR, immunohistochemistry and immunoblotting. In vitro, RGS5 was found significantly down-regulated after mitogenic stimulation of SMCs. Overexpression of RGS5 or, even more prominently, the C2A-RGS5 mutant prevented SMC proliferation and migration. In contrast, the siRNA-mediated knockdown of RGS5 significantly augmented SMC proliferation. Following overexpression of RGS5, FACS analysis of propidium iodide-stained cells indicated cell cycle arrest in G0/G1 phase. Mechanistically, inhibition of ERK1/2 phosphorylation and MAPK downstream signaling was found to be responsible for the anti-proliferative effect since over expression of a constitutive active form of MEK reversed the growth-inhibitory effect of of RGS5. Following wire-induced injury, adenoviral-mediated overexpression of RGS5 or C2A-RGS5 significantly decreased ERK phosphorylation, SMC proliferation and neointima formation in vivo (n=8; p&lt;0.001). Conclusions: Down-regulation of RGS5 is an important prerequisite for SMC proliferation and neointima Formation. Therefore, reconstitution of RGS5 levels might represent a promising therapeutic option to prevent vascular remodeling processes.

Abstract 441: Rgs5 Controls Myogenic Responses of Vascular Smooth Muscle Cells

Contraction of vascular smooth muscle cells (VSMCs) in response to an increase in blood pressure is pivotal for maintaining blood flow and constitutes both consequence and cause of chronic hypertension. While a plethora of contraction-mediating mechanisms has been delineated, not much is known about molecular determinants regulating the responses of VSMCs to an increase in wall stress or biomechanical stretch. In this context, we reported that conditional ablation of Junb - a subunit of the transcription factor AP-1 (activator protein 1) - interferes with the expression of myosin light chain 9 and consequently impaired myogenic responses of arteries. We hypothesized that the arterial circumferential wall stress is increased under these conditions which may influence the VSMC phenotype and vessel wall architecture. In fact, Junb-deficient arteries showed structural remodeling as evidenced by a ~2-3-fold decrease in collagen type I and IV content (n=5, p&lt;0.05). cDNA microarray analyses revealed that expression of regulator of G-protein signaling 5 (RGS5) was up-regulated in VSMCs (~6-fold, n=4, p&lt;0.001) isolated from Junb-deficient arteries which was confirmed in vivo but not mediated by AP-1. However, elevation of wall stress by volume-induced hypertension in vivo or exposure of VSMCs to biomechanical stretch in vitro was sufficient to trigger RGS5 expression (3-fold, n=3, p&lt;0.05). Overexpression of this regulator activates RhoA and enhanced stretch-induced responses of VSMCs such as stress fiber formation while its knockdown showed opposite effects. In line with this, RGS5-deficient arteries show an impaired pressure-mediated constriction (n=8, p&lt;0.05) and both the hypertension-induced increase in diastolic blood pressure as well as structural remodeling of the arterial vessel wall were significantly attenuated in RGS5-deficient mice. Collectively, these findings indicate that biomechanical stretch mediates the expression of RGS5 in VSMCs to enhance stretch-dependent responses as a prerequisite for adequate adaptive vascular remodeling processes. This mechanism may establish RGS5 as a promising target for future strategies to combat, e.g. the deleterious consequences of arterial hypertension such as arterial stiffening.

THE ROLE OF RGS5 IN MEDIATING THE PLEIOTROPIC EFFECTS OF STATINS IN VASCULAR SMOOTH MUSCLE CELLS

Statins have been demonstrated to exert pleiotropic anti-atherogenic effects in vascular smooth muscle cells (VSMCs), including inhibition of VSMC migration and proliferation. However, the mechanism underlying this inhibition is not fully understood. A previous microarray study on aortas of statin-treated mice have demonstrated regulator of G-protein signaling 5 (RGS5) to show the greatest increase in expression among non-cytoskeletal proteins. We hypothesized that by inhibiting G-protein signaling involved in VSMC recruitment, RGS5 may contribute to the pleiotropic effects of statins in VSMCs. VSMCs were isolated from mouse aortas and incubated at different concentrations of fluvastatin for 24 hours. Quantitative real-time polymerase chain reaction analysis demonstrated that RGS5 expression significantly increased with 10 μM and 100 μM fluvastatin as compared to vehicle-treated controls (P<0.05), but not with 1 μM fluvastatin. Preliminary time profile studies with 10 μM fluvastatin suggest that the upregulation of RGS5 occurs after 18 hours, which remains stable for up to 48 hours. In order to assess the role of RGS5 during atherosclerosis progression, RGS5/apoE dKO mice, along with RGS5 WT/apoE KO littermate mice were generated and placed on a high cholesterol diet for 12 weeks. During this period, RGS5/apoE dKO mice displayed markedly reduced survival as compared to RGS5 WT/apoE KO mice (P<0.05). Subsequent Oil-Red O stained plaque size analysis in the thoracic aorta demonstrated a larger normalized lesion size in RGS5/apoE dKO mice as compared to littermate RGS5 WT/apoE KO mice (P<0.05). These results suggest an inhibitory role of RGS5 in the progression of atherosclerosis, and that its upregulation in VSMCs following statin treatment may contribute to the therapeutic pleiotropic effects of statins. Future experiments will assess the role of the statin-induced RGS5 upregulation in modulating signaling pathways involved in VSMC recruitment.

Antiatherosclerotic Effect of Korean Red Ginseng Extract Involves Regulator of G-Protein Signaling 5

Regulator of G-protein signaling 5 (RGS5), an inhibitor of Gα(q) and Gα(i) activation, has been reported to have antiatherosclerosis. Previous studies showed antiatherosclerotic effect of Korean red ginseng water extract (KRGE) via multiple signaling pathways. However, potential protective effect of KRGE through RGS5 expression has not been elucidated. Here, we investigated the antiatherosclerotic effect of KRGE in vivo and in vitro and its role on RGS5 mRNA expression. Elevated levels of total cholesterol, lactate dehydrogenase (LDH), and triglyceride (TG) in western diet groups of low-density lipoprotein receptor deficient LDLr−/− mice were reversed by oral administration of KRGE. KRGE suppressed transcriptional activity of tumor necrotic factor alpha (TNF-α), interleukin-6 (IL-6), and leptin in adipose tissue. It also potently repressed western diet-induced atheroma formation in aortic sinus. While KRGE showed reduced mRNA expression of inducible nitric oxide synthase (iNOS), cyclooxygenase-2 (COX-2), IL-1β, IL-6, and TNF-α in LPS-stimulated RAW264.7 cells, it enhanced mRNA expression of RGS5. Moreover, RGS5 siRNA transfection of microglia cells pretreated with KRGE reversed its inhibitory effect on the expression of iNOS, COX-2, and IL-1β mRNA. In conclusion, KRGE showed antiatherosclerotic and anti-inflammatory effects in western diet fed LDLr−/− mice and this effect could partly be mediated by RGS5 expression.

Over-expression of regulator of G protein signaling 5 promotes tumor metastasis by inducing epithelial-mesenchymal transition in hepatocellular carcinoma cells

Hepatocellular carcinoma (HCC) is the second leading cause of cancer-related deaths worldwide. The regulator of G-protein signaling 5 (RGS5) has been reported to be highly expressed in some malignant tumors. However, its expression and role in HCC has not been reported. The expression of RGS5 was examined in liver cancer tissues and cell lines by real-time quantitative PCR. The cell migration and invasion was investigated by wound healing and transwell invasion assay. The epithelial-mesenchymal transition markers were detected by Western blotting or immunofluorescence. We observed that RGS5 is over-expressed in most of liver cancer tissue samples and cell lines compared with matched normal samples. Further analysis showed that the over-expression of RGS5 is associated with liver cancer recurrence, venous infiltration, and patients' poor survival. Next, we found that knockdown of RGS5 significantly inhibits liver cancer cell migration and invasion in highly invasive liver cancer cells. Furthermore, we found that over-expression of RGS5 induces epithelial-mesenchymal transition in epithelial liver cancer cells. These results indicate that over-expression of RGS5 promotes tumor metastasis by inducing epithelial-mesenchymal transition in HCC.

Regulator of G‐protein Signaling 5 reduces HeyA8 ovarian cancer cell proliferation and extends survival in a murine tumor model

The regulator of G‐protein signaling 5 (RGS5) belongs to a family of GTPase activators that terminate signaling cascades initiated by extracellular mediators and GPCRs. One RGS5 role is as a pericyte biomarker influencing the switch to angiogenesis during malignant progression. Its other role is to promote apoptosis in hypoxic environments. We set out to clarify the extent to which RGS5 expression regulates tumor progression – whether it plays a pathogenic or protective role. We thus constructed an inducible gene expression system to achieve RGS5 expression in HeyA8‐ MDR ovarian cancer cells. Through this we observed that inducible RGS5 expression significantly reduces in vitro BrdU‐positive HeyA8‐MDR cells. Interestingly, mice bearing RGS5‐ expressing tumors demonstrated an increase in survival compared with controls, which might be attributed to the vast regions of necrosis observed by pathological examination. Additionally, mice bearing RGS5‐expressing tumors were less likely to have ulcerated tumors. Taken together, this data supports the idea that temporal expression and stabilization of RGS5 could be a valuable tactic within the context of a multi‐component approach for modulating tumor progression.

Nanogold and 5-fluorouorouracil conjugation affecting hepatic tumor vascular and inhibiting tumor growth

Objective To observe the effect of hepatic tumor vascular and the carcinoma growth with nangold and 5-fluorouracil (5-Fu) conjugation.Methods Hepatocellular cancer cells of the line H22 were injected subcutaneously into the right armpits of 21 BALB/C nude mice.When the size of transplanted tumor reached about 7-8 mm,they were divided into 3 groups,7 mice in each group,5-Fu and nanogold 0.2 ml was injected respectively in conjugation group,only 5-Fu was injected in 5-Fu group,and the same volume normal saline was used in control group.After continuous drug use for 7 days,the mice were sacrifled,the tumor size and weight were measured,the microvacular density (MVD) and mature pericyte coverage index (MPI) of tumor were detected by immunohistechemical staining,concentration of 5-Fu in tumor was detected by high performance liquid chromatography (HPLC) ; regulator of G-protein signaling-5(RGS-5) was detected by western blotting.Results (1) The tumor volume and the MVD in the conjugation group were (1.487 ± 0.859) cm3 and (23 ± 7) vessels/mm2,less than the 5-Fu group [(2.137 ±1.047) cm3 and (43 ± 12) vessels/mm2] ; Also the MPI and the percentage of 5-Fu in tumor were (37.5 ± 11.3)％ and (5.37 ±0.41) mg/L respectively in the conjugation group,more than the other two groups (P ＜0.05).(2)Western blotting showed the expression of RGS-5 in conjugation group were less than the other groups.Conclusion (1)Nangold enhanced the effect of 5-Fu anti-hepatic tumor,inhibiting the growth of carcinoma,it could be benefit for the 5-Fu penetrating the tumor inside.(2) Nangold could inhibit the expression of RGS-5 and upward MPI,make tumor microvessel normal. Key words: Nanogold; Fluorouacil; Tumor vascular; G-protein signaling-5

Regulator of G-Protein Signaling 5 Controls Blood Pressure Homeostasis and Vessel Wall Remodeling

Regulator of G-protein signaling 5 (RGS5) modulates G-protein-coupled receptor signaling and is prominently expressed in arterial smooth muscle cells. Our group first reported that RGS5 is important in vascular remodeling during tumor angiogenesis. We hypothesized that RGS5 may play an important role in vessel wall remodeling and blood pressure regulation. To demonstrate that RGS5 has a unique and nonredundant role in the pathogenesis of hypertension and to identify crucial RGS5-regulated signaling pathways. We observed that arterial RGS5 expression is downregulated with chronically elevated blood pressure after angiotensin II infusion. Using a knockout mouse model, radiotelemetry, and pharmacological inhibition, we subsequently showed that loss of RGS5 results in profound hypertension. RGS5 signaling is linked to the renin-angiotensin system and directly controls vascular resistance, vessel contractility, and remodeling. RGS5 deficiency aggravates pathophysiological features of hypertension, such as medial hypertrophy and fibrosis. Moreover, we demonstrate that protein kinase C, mitogen-activated protein kinase/extracellular signal-regulated kinase, and Rho kinase signaling pathways are major effectors of RGS5-mediated hypertension. Loss of RGS5 results in hypertension. Loss of RGS5 signaling also correlates with hyper-responsiveness to vasoconstrictors and vascular stiffening. This establishes a significant, distinct, and causal role of RGS5 in vascular homeostasis. RGS5 modulates signaling through the angiotensin II receptor 1 and major Gαq-coupled downstream pathways, including Rho kinase. So far, activation of RhoA/Rho kinase has not been associated with RGS molecules. Thus, RGS5 is a crucial regulator of blood pressure homeostasis with significant clinical implications for vascular pathologies, such as hypertension.

PO-86 Cancer cells modify the microenvironment: RGS5, a novel endothelial protein of the abnormal tumor vasculature

PO-86 Cancer cells modify the microenvironment: RGS5, a novel endothelial protein of the abnormal tumor vasculature

Regulator of G-Protein Signaling–5 Inhibits Bronchial Smooth Muscle Contraction in Severe Asthma

Severe asthma is associated with fixed airway obstruction attributable to inflammation, copious luminal mucus, and increased airway smooth muscle (ASM) mass. Paradoxically, studies demonstrated that the hypertrophic and hyperplastic ASM characteristic of severe asthma has reduced contractile capacity. We compared the G-protein-coupled receptor (GPCR)-induced Ca(2+) mobilization and expression of GPCRs and signaling proteins related to procontractile signaling in ASM derived postmortem from subjects who died of nonrespiratory causes, with cells from subjects who died of asthma. Despite the increased or comparable expression of contraction-promoting GPCRs (bradykinin B2 or histamine H1 and protease-activated receptor 1, respectively) in asthmatic ASM cells relative to cells from healthy donors, asthmatic ASM cells exhibited reduced histamine-induced Ca(2+) mobilization and comparable responses to bradykinin and thrombin, suggesting a postreceptor signaling defect. Accordingly, the expression of regulator of G-protein signaling-5 (RGS5), an inhibitor of ASM contraction, was increased in cultured, asthmatic ASM cells and in bronchial smooth muscle bundles of both human subjects with asthma and allergen-challenged mice, relative to those of healthy human subjects or naive mice. The overexpression of RGS5 impaired the release of Ca(2+) to thrombin, histamine, and carbachol, and reduced the contraction of precision-cut lung slices to carbachol. These results suggest that increased RGS5 expression contributes to decreased myocyte shortening in severe and fatal asthma.

Regulator of G-Protein Signaling 5 Reduces HeyA8 Ovarian Cancer Cell Proliferation and Extends Survival in a Murine Tumor Model.

The regulator of G-protein signaling 5 (RGS5) belongs to a family of GTPase activators that terminate signaling cascades initiated by extracellular mediators and G-protein-coupled receptors. RGS5 has an interesting dual biological role. One functional RGS5 role is as a pericyte biomarker influencing the switch to angiogenesis during malignant progression. Its other functional role is to promote apoptosis in hypoxic environments. We set out to clarify the extent to which RGS5 expression regulates tumor progression—whether it plays a pathogenic or protective role in ovarian tumor biology. We thus constructed an inducible gene expression system to achieve RGS5 expression in HeyA8-MDR ovarian cancer cells. Through this we observed that inducible RGS5 expression significantly reduces in vitro BrdU-positive HeyA8-MDR cells, although this did not correlate with a reduction in tumor volume observed using an in vivo mouse model of ovarian cancer. Interestingly, mice bearing RGS5-expressing tumors demonstrated an increase in survival compared with controls, which might be attributed to the vast regions of necrosis observed by pathological examination. Additionally, mice bearing RGS5-expressing tumors were less likely to have ulcerated tumors. Taken together, this data supports the idea that temporal expression and stabilization of RGS5 could be a valuable tactic within the context of a multicomponent approach for modulating tumor progression.

Regulator of G-protein signaling 5 (RGS5) protein: a novel marker of cancer vasculature elicited and sustained by the tumor’s proangiogenic microenvironment

We previously identified regulator of G-protein signaling 5 (RGS5) among several genes expressed by tumor-derived endothelial cells (EC). In this study, we provide the first in vivo/ex vivo evidence of RGS5 protein in the vasculature of ovarian carcinoma clinical specimens and its absence in human ovaries. Consistent with this, we show higher amounts of Rgs5 transcript in EC isolated from human cancers (as opposed to normal tissues) and demonstrate that expression is sustained by a milieu of factors typical of the proangiogenic tumor environment, including vascular endothelial growth factor (VEGF) and basic fibroblast growth factor (FGF-2). Supporting these findings, we show elevated levels of Rgs5 mRNA in the stroma from strongly (as opposed to weakly) angiogenic ovarian carcinoma xenografts and accordingly, we also show more of the protein associated to the abnormal vasculature. RGS5 protein predominantly colocalizes with the endothelium expressing platelet/endothelial cell adhesion molecule-1 (PECAM-1/CD31) and to a much lesser extent with perivascular/mural cells expressing platelet-derived growth factor receptor-beta (PDGFR-β) or alpha smooth muscle actin (αSMA). To toughen the relevance of the findings, we demonstrate RGS5 in the blood vessels of other cancer models endowed with a proangiogenic environment, such as human melanoma and renal carcinoma xenografts; to the contrary, it was undetectable in the vasculature of normal mouse tissues. RGS5 expression by the cancer vasculature triggered and retained by the proangiogenic microenvironment supports its exploitation as a novel biomarker and opens the path to explore new possibilities of therapeutic intervention aimed at targeting tumor blood vessels.Electronic supplementary materialThe online version of this article (doi:10.1007/s00018-011-0862-8) contains supplementary material, which is available to authorized users.