Serum R-Spondin 1 Is a New Surrogate Marker for Obesity and Insulin Resistance

BACKGROUND: Recent in vivo studies indicated that R-spondin 1 (RSPO1) regulates food intake and increases insulin secretion, but its role in humans remains unknown. This study investigated the association between serum levels of RSPO1 and diverse metabolic parameters in humans. METHODS: The study population consisted of 43 subjects with newly diagnosed diabetes mellitus, and 79 non-diabetic participants. Serum levels of RSPO1 were measured using the enzyme-linked immunosorbent assay. The relationships between circulating RSPO1 and diverse metabolic parameters were analyzed. RESULTS: Circulating RSPO1 levels increased to a greater extent in the obese group than in the lean group. Moreover, serum levels of RSPO1 were higher in the insulin-resistant group than in the insulin-sensitive group. Serum levels of RSPO1 were significantly correlated with a range of metabolic parameters including body mass index, fasting C-peptide, homeostasis model assessment of insulin resistance index, and lipid profile. Moreover, levels were significantly associated with insulin resistance and obesity in non-diabetic subjects. CONCLUSION: This study demonstrated the association between serum levels of RSPO1 and a range of metabolic parameters in humans. Serum levels of RSPO1 are significantly related to obesity and insulin resistance, although the precise mechanisms remain unknown.

Expression and its clinical significance of G-protein coupled receptor 49 in pancreatic carcinoma / 中华消化杂志

Objective To investigate the clinical significance and biological role of G-protein coupled receptor 49(GPR49) expression in pancreatic carcinoma.Methods GPR49 expression in tumor and adjacent normal tissues of 77 patients with pancreatic cancer was compared by tissue microarray and immunohistochemistry.And then, the GPR49 expression levels in the tumor tissues of patients with different pathological grades and clinical stages were analyzed.GPR49 positive pancreatic cancer cell line CFPAC-1 was taken as cellular model.CFPAC-1 cells were stimulated with roof plate-specific spondin(RSPO)1, the ligand of GPR49, in vitro.The effect of RSPO1 on CFPAC-1 cells proliferation was evaluated with cell counting.The effect of RSPO1 on the expression of membrane molecular CD44 in CFPAC-1 cells was detected by flow cytometry.CFPAC-1 cells incubated with RSPO1 were subcutaneously implanted into nude mice.And then, the time of tumor formation and tumor size were observed.T test and single factor analysis of variance were performed for statistical analysis.Results GPR49 was widely expressed in all 77 pancreatic cancer tissues.By immunohistochemistry, the score of GPR49 expression in pancreatic cancer tissues was 9.0±2.4, which was higher than that of adjacent normal tissues (5.7±2.4), and the difference was statistically significant (t=8.995, P0.05).The results of experiments in vitro indicated that RSPO1 could promote CFPAC-1 cells proliferation and up-regulate CD44 expression in CFPAC-1 cells.Experiments in vivo demonstrated that after 30 days the tumor volume of mice implanted with RSPO1-pretreated CFPAC-1 cells was (606.0±188.0) mm3, which was larger than that of PBS-pretreated group ((364.2±83.7) mm3), and the difference was statistically significant (t=2.616, P=0.031).Conclusion GPR49 is widely expressed in pancreatic cancer cells and RSPO1/GPR49 pathway has play a role in promoting the proliferation of pancreatic cancer cells, which might be a potential target for interfering pancreatic cancer.

Rspo1 promotes osteoblast differentiation via Wnt signaling pathway.

R-spondin (Rspo)s proteins are a new group of Wnt/beta-catenin signaling agonists. These signaling molecules are known to be involved in the developmental stages of skeletal system. Recent studies in various murine osteoblast models have proposed that Rspo1 may interact with Wnt signaling pathway to induce differentiation in osteoblasts. Though findings in murine osteoblasts implicate a synergestic role of Rspo1 with Wnt signaling, still no study has addressed the similar role in more clinically applicable osteoblast models i.e., human cell lines or primary cells. Therefore, in the present study, we investigated the possible role of Rspo1 during differentiation process of human in vitro osteoblast cell models like primary osteoblasts or human osteoprogenitor cell line hFOB1.19 along with murine preosteoblast cell line MC3T3 E-1. Our results showed increase in Rspo1 at transcript level during differentiating phase of human primary osteoblasts and human FOB1.19 cells. We also found that Rspo1 (100 ng/mL) acts additively with Wnt3a to activate Wnt signaling, as confirmed by luciferase activity after transfection of TOPFLASH construct to hFOB1.19 cells. Similar additive role of Rspo1 and Wnt3a was apparent in alkaline phosphatase (ALP) activity analysis of human primary cells. Moreover, a reduction in ALP activity was observed with knock-down of Rspo1 by transfected shRNA in hFOB1.19 cells. These results suggested the possibility of autocrine regulation by Rspo1 on the osteogenic activities in human in vitro osteoblast models. Furthermore, these results were corroborated in MC3T3-E1, murine osteoblast cell model. Osteoblastic differentiation was induced by transfection of Rspo1 which was confirmed by increased ALP staining and qRT-PCR analysis of osteogenic markers, such as Runx2 and osteocalcin. In conclusion, present study highlights the role of Rspo1 in bone remodeling where it activates Wnt signaling to induce differentiation, as shown in human as well murine in vitro osteoblast cell models.