PGE2-EP2/EP4 signaling elicits immunosuppression by driving the mregDC-Treg axis in inflammatory tumor microenvironment.

Active inflammation generally promotes immune activation. However, in the tumor microenvironment (TME), active inflammation occurs in parallel with immunosuppression, and both contribute to tumor growth. Why inflammation does not lead to immune activation in TME remains unclear. In this study, using the immune checkpoint inhibitor-insensitive mouse cancer model and single-cell RNA sequencing, we show that PGE2-EP2/EP4 signaling simultaneously promotes active inflammation by inducing expression of the NF-κB genes in myeloid cells and elicits immunosuppression by driving the mregDC (mature DC enriched in immunoregulatory molecules)-Treg (regulatory T cell) axis for Treg recruitment and activation in the tumor. Importantly, the EP2/EP4 expression level is strongly correlated with the gene signatures of both active inflammation and the mregDC-Treg axis and has significant prognosis value in various human cancers. Thus, PGE2-EP2/EP4 signaling functions as the key regulatory node linking active inflammation and immunosuppression in TME, which can be targeted by EP2 and EP4 antagonists for cancer therapeutics.

Decoding cell death signals in liver inflammation.

Inflammation can be either beneficial or detrimental to the liver, depending on multiple factors. Mild (i.e., limited in intensity and destined to resolve) inflammatory responses have indeed been shown to exert consistent hepatoprotective effects, contributing to tissue repair and promoting the re-establishment of homeostasis. Conversely, excessive (i.e., disproportionate in intensity and permanent) inflammation may induce a massive loss of hepatocytes and hence exacerbate the severity of various hepatic conditions, including ischemia-reperfusion injury, systemic metabolic alterations (e.g., obesity, diabetes, non-alcoholic fatty liver disorders), alcoholic hepatitis, intoxication by xenobiotics and infection, de facto being associated with irreversible liver damage, fibrosis, and carcinogenesis. Both liver-resident cells (e.g., Kupffer cells, hepatic stellate cells, sinusoidal endothelial cells) and cells that are recruited in response to injury (e.g., monocytes, macrophages, dendritic cells, natural killer cells) emit pro-inflammatory signals including - but not limited to - cytokines, chemokines, lipid messengers, and reactive oxygen species that contribute to the apoptotic or necrotic demise of hepatocytes. In turn, dying hepatocytes release damage-associated molecular patterns that-upon binding to evolutionary conserved pattern recognition receptors-activate cells of the innate immune system to further stimulate inflammatory responses, hence establishing a highly hepatotoxic feedforward cycle of inflammation and cell death. In this review, we discuss the cellular and molecular mechanisms that account for the most deleterious effect of hepatic inflammation at the cellular level, that is, the initiation of a massive cell death response among hepatocytes.

The Prostaglandin E Receptor Agonists Increase Granulocyte Macrophage Colony-Stimulating Factor in Prostate Cancer Cells / 대한비뇨기과학회지

PURPOSE: The predilection for prostate carcinoma cells to metastasize to bone suggests the hypothesis that bone and/or bone marrow-derived factors may promote prostate carcinoma cell growth and/or their survival. To date, little work has been performed to characterize the nature of granulocyte macrophage colony-stimulating factor (GM-CSF) and the expression of prostaglandin E2 receptors (EPs) in prostate cancer (PC) cells. The aim of this study is to evaluate the effects of GM-CSF on cell proliferation and the effects of EP agonists on the production of GM-CSF in the PC-3 cells. MATERIALS AND METHODS: The bone-derived PC-3 cell line was used in this study. Reverse transcription polymerase chain reaction (RT-PCR) was performed to detect the mRNA expression of EP1, 2, 3 and 4 and hGM- CSF. 3-(4,5-dimethylthiazol-2-yl)-2,5 diphenyltetrazolium bromide (MTT) assay was done to estimate the viability of PC-3 cells after hGM-CSF treatment. hGM-CSF was measured by enzyme-linked immunosorbent assay (ELISA) after treatments with the EPs agonist at 10(-10), 10(-8), 10(-6)M, respectively. RESULTS: EP2, 3 and 4 and hGM-CSF were expressed in the PC-3 cell line. Viability of the PC-3 cells was significantly increased by hGM-CSF administration in a dose- and time-dependent manner. Also, our data indicated that EP2, 3 and especially 4 agonists induced a significant dose- dependent increase in hGM-CSF production in comparison to the control group in the conditioned ELISA medium. CONCLUSIONS: These results suggest that GM-CSF may be part of a network of an autocrine-regulatory loop system that modulates the biologic activity of prostate carcinoma cells. Our data suggest that GM-CSF and EPs may represent a possible novel therapeutic target that manipulates the proliferative rate of prostate tumors.

The Prostaglandin E Receptor Agonists Increase Granulocyte Macrophage Colony-Stimulating Factor in Prostate Cancer Cells / 대한비뇨기과학회지

PURPOSE: The predilection for prostate carcinoma cells to metastasize to bone suggests the hypothesis that bone and/or bone marrow-derived factors may promote prostate carcinoma cell growth and/or their survival. To date, little work has been performed to characterize the nature of granulocyte macrophage colony-stimulating factor (GM-CSF) and the expression of prostaglandin E2 receptors (EPs) in prostate cancer (PC) cells. The aim of this study is to evaluate the effects of GM-CSF on cell proliferation and the effects of EP agonists on the production of GM-CSF in the PC-3 cells. MATERIALS AND METHODS: The bone-derived PC-3 cell line was used in this study. Reverse transcription polymerase chain reaction (RT-PCR) was performed to detect the mRNA expression of EP1, 2, 3 and 4 and hGM- CSF. 3-(4,5-dimethylthiazol-2-yl)-2,5 diphenyltetrazolium bromide (MTT) assay was done to estimate the viability of PC-3 cells after hGM-CSF treatment. hGM-CSF was measured by enzyme-linked immunosorbent assay (ELISA) after treatments with the EPs agonist at 10(-10), 10(-8), 10(-6)M, respectively. RESULTS: EP2, 3 and 4 and hGM-CSF were expressed in the PC-3 cell line. Viability of the PC-3 cells was significantly increased by hGM-CSF administration in a dose- and time-dependent manner. Also, our data indicated that EP2, 3 and especially 4 agonists induced a significant dose- dependent increase in hGM-CSF production in comparison to the control group in the conditioned ELISA medium. CONCLUSIONS: These results suggest that GM-CSF may be part of a network of an autocrine-regulatory loop system that modulates the biologic activity of prostate carcinoma cells. Our data suggest that GM-CSF and EPs may represent a possible novel therapeutic target that manipulates the proliferative rate of prostate tumors.