Human Anti-Human PTGDR2 monoclonal Antibody, clone SFB609 [PE]

Introduction Cancer stem cells have been implicated angiogenesis of tumor and invasiveness, drug resistance in tumors. Yes-associated protein 1 (YAP) owns carcinogenic roles in various organs, but the role of YAP in cancer stem cells of gastric cancer (GC) remains unclear. In this study, we explored the function and mechanism of YAP in GC cancer stem cells. Materials and methods, and results First, we confirmed that the expression of YAP mRNA and protein in GC tissues was higher than in adjacent tissues by RT-PCR, western blot and immunohistochemistry. Immunofluorescence staining of the GC tissues revealed that the region of YAP expression coincided with the region of expression of the cancer stem cell marker SALL4 but did not overlap with that of the epithelial marker cytokeratin 14 (CK14). Additional research revealed that spherical cells expressed relatively high levels of YAP protein, and YAP overexpression reinforced self-renewal and expression of stem cell markers in the GC cells. Knockdown the expression of YAP reversed this phenomenon. Second, we examined the expression patterns of lipocalin-type prostaglandin D2 synthase (L-PTGDS) and prostaglandin D2 receptor 2 (PTGDR2) in GC tissues and proved that there was negatively correlation between the expression of L-PTGDS and PTGDR2 and YAP in GC tissues. Finally, we confirmed that YAP inhibited the expression of L-PTGDS and PTGDR2 by gain- and loss-of-function experiments. Moreover, the overexpression of L-PTGDS and PTGDR2 suppressed the proliferation and self-renewal induced by YAP in vitro and reversed the pro-tumor effect of YAP in vivo. Conclusion Our results revealed a novel function of YAP and the mechanism underlying cancer stem cell regulation by YAP.

Aims/Hypothesis GPR44 (DP2, PTGDR2, CRTh2) is the receptor for the pro-inflammatory mediator prosta-glandin D-2 (PGD(2)) and it is enriched in human islets. In rodent islets, PGD(2) is produced in response to glucose, suggesting that the PGD(2)-GPR44/DP2 axis may play a role in human islet function during hyperglycemia. Consequently, the aim of this work was to elucidate the insulinotropic role of GPR44 antagonism in vitro in human beta-cells and in type 2 diabetes (T2DM) patients. Methods We determined the drive on PGD(2) secretion by glucose and IL-1 beta, as well as, the impact on insulin secretion by pharmacological GPR44/DP2 antagonism (AZD1981) in human islets and beta-cells in vitro. To test if metabolic control would be improved by antagonizing a hyperglycemia-driven increased PGD(2) tone, we performed a proof-of-mechanism study in 20 T2DM patients (average 54 years, HbA1c 9.4%, BMI 31.6 kg/m(2)). The randomized, double-blind, placebo-controlled cross-over study consisted of two three-day treatment periods (AZD1981 or placebo) separated by a three-day wash-out period. Mixed meal tolerance test (MMTT) and intravenous graded glucose infusion (GGI) was performed at start and end of each treatment period. Assessment of AZD1981 pharmacokinetics, glucose, insulin, C-peptide, glucagon, GLP-1, and PGD(2) pathway biomarkers were performed. Results We found (1) that PGD(2) is produced in human islet in response to high glucose or IL-1 beta, but likely by stellate cells rather than endocrine cells; (2) that PGD(2) suppresses both glucose and GLP-1 induced insulin secretion in vitro; and (3) that the GPR44/DP2 antagonist (AZD1981) in human beta-cells normalizes insulin secretion. However, AZD1981 had no impact on neither glucose nor incretin dependent insulin secretion in humans (GGI AUC (C-peptide 1-2h) and MMTT AUC (Glucose 0-4h) LS mean ratios vs placebo of 0.94 (80% CI of 0.90-0.98, p = 0.12) and 0.99 (90% CI of 0.94-1.05, p = 0.45), despite reaching the expected antagonist exposure. Conclusion/Interpretation Pharmacological inhibition of the PGD(2)-GPR44/DP2 axis has no major impact on the modulation of acute insulin secretion in T2DM patients.