Prostaglandin E2-EP4 signaling shapes immunosuppressive tumor microenvironment in human tumors by suppressing bioenergetics and ribosome biogenesis in infiltrating immune cells [RNA-seq]
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ABSTRACT: Prostaglandins (PGs) are inflammatory mediators. Aspirin-like non-steroidal anti-inflammatory drugs (NSAIDs) inhibit cyclooxygenase (COX), an initiating enzyme of PG biosynthesis1. Daily use of aspirin-like drugs lowers the risk of cancer death not only prophylactically but therapeutically suggesting critical roles of PGs in cancer. However, general mechanisms by which PGs contribute to progression of a wide variety of human cancers remain elusive. Here, using scRNAseq analysis comparing immune cells infiltrating human tumors and a syngeneic mouse tumor, we have dissected this issue. We found that in human tumors, COX is dominantly expressed in infiltrating myeloid cells, and, among PG receptors, PGE receptor EP4 and to a less extent EP2 are expressed in both T cells and myeloid cells. DEG analysis between PTGER4hi and PTGER4lo CD8+ T cells indicates downregulation of IL-2-STAT5 signaling, oxidative phosphorylation, glycolysis and Myc targets in EP4hi CD8+ T cells, as revealed by suppressed expression of IL-2 receptor subunit gene and genes of OXPHOS, glycolytic enzymes and ribosomal proteins (RPs). Similar downregulation of OXPHOS, glycolytic enzymes and RP genes is found in PTGER4hi myeloid cells. Notably, such downregulation of OXPHOS and RP genes was found in immune cells infiltrating LLC1 mouse tumor, and reversed by treatment of tumor-bearing mice with EP2 and EP4 antagonists. In vitro in CD8+ T cells, EP4 is induced upon TCR activation and PGE2 acts on EP4, downregulates Il2ra expression and suppresses expression of Myc and PGC-1, thereby impairing both mitochondria and glycolysis as well as ribosome biogenesis in these cells. Similarly, EP4 is induced upon activation in macrophages and PGE2 downregulates Myc and OXPHOS pathwaysin these cells irrespective of other stimuli. These results demonstrate that PGE2 shapes immunosuppressive tumor microenvironment by hampering bioenergetic metabolism and ribosome biogenesis in infiltrating immune cells via EP4 receptor.
Project description:Prostaglandins (PGs) are inflammatory mediators. Aspirin-like non-steroidal anti-inflammatory drugs (NSAIDs) inhibit cyclooxygenase (COX), an initiating enzyme of PG biosynthesis1. Daily use of aspirin-like drugs lowers the risk of cancer death not only prophylactically but therapeutically suggesting critical roles of PGs in cancer. However, general mechanisms by which PGs contribute to progression of a wide variety of human cancers remain elusive. Here, using scRNAseq analysis comparing immune cells infiltrating human tumors and a syngeneic mouse tumor, we have dissected this issue. We found that in human tumors, COX is dominantly expressed in infiltrating myeloid cells, and, among PG receptors, PGE receptor EP4 and to a less extent EP2 are expressed in both T cells and myeloid cells. DEG analysis between PTGER4hi and PTGER4lo CD8+ T cells indicates downregulation of IL-2-STAT5 signaling, oxidative phosphorylation, glycolysis and Myc targets in EP4hi CD8+ T cells, as revealed by suppressed expression of IL-2 receptor subunit gene and genes of OXPHOS, glycolytic enzymes and ribosomal proteins (RPs). Similar downregulation of OXPHOS, glycolytic enzymes and RP genes is found in PTGER4hi myeloid cells. Notably, such downregulation of OXPHOS and RP genes was found in immune cells infiltrating LLC1 mouse tumor, and reversed by treatment of tumor-bearing mice with EP2 and EP4 antagonists. In vitro in CD8+ T cells, EP4 is induced upon TCR activation and PGE2 acts on EP4, downregulates Il2ra expression and suppresses expression of Myc and PGC-1, thereby impairing both mitochondria and glycolysis as well as ribosome biogenesis in these cells. Similarly, EP4 is induced upon activation in macrophages and PGE2 downregulates Myc and OXPHOS pathwaysin these cells irrespective of other stimuli. These results demonstrate that PGE2 shapes immunosuppressive tumor microenvironment by hampering bioenergetic metabolism and ribosome biogenesis in infiltrating immune cells via EP4 receptor.
Project description:While the role of prostaglandin E2 (PGE2) in promoting malignant progression is well-established, how to optimally block the activity of PGE2 signaling remains to be demonstrated. Clinical trials with prostaglandin pathway targeted agents have shown activity but without sufficient significance or dose-limiting toxicities that have prevented approval. PGE2 signals through four receptors (EP1-4) to modulate tumor progression. EP2 and EP4 signaling exacerbates tumor pathology and is immunosuppressive through potentiating cAMP production. EP1 and EP3 signaling has the opposite effect through increasing IP3 and decreasing cAMP. Using available small molecule antagonists of single EP receptors, the COX-2 inhibitor celecoxib, or a novel dual EP2/EP4 antagonist generated in this investigation, we tested which approach to block PGE2 signaling optimally restored immunologic activity in mouse and human immune cells and antitumor activity in syngeneic, spontaneous and xenograft tumor models. We found that dual antagonism of EP2 and EP4 together significantly enhanced the activation of PGE2-suppressed mouse and human monocytes and CD8+ T cells in vitro as compared to single EP antagonists. CD8+ T cell activation was dampened by single EP1 and EP3 antagonists. Dual EP2/EP4 PGE2 receptor antagonists increased TME lymphocyte infiltration and significantly reduced disease burden in multiple tumor models, including in the adenomatous polyposis coli (APC)min+/- spontaneous colorectal tumor model, compared to celecoxib. These results support a hypothesis that redundancy of EP2 and EP4 receptor signaling necessitates a therapeutic strategy of dual blockade of EP2 and EP4. Here we describe TPST-1495, a first-in-class orally available small molecule dual EP2/EP4 antagonist.
Project description:IL-23 induces ptgs2 encoding cyclooxygenase 2 in Th17 cells and produces PGE2, which acts back on PGE2 receptors EP2 and EP4 in these cells and enhances IL-23-induced expression of an IL-23 receptor subunit gene, Il23r, by activating STAT3, CREB1 and NF-κB through cAMP-protein kinase A signaling. This PGE2 signaling also induces expression of various inflammation-related genes, which possibly function in Th17 cell-mediated pathology. Combined deletion of EP2 and EP4 selectively in T cells suppressed accumulation of IL-17A+ and IL-17A+IFN-γ+ pathogenic Th17 cells and abolished skin inflammation in IL-23-induced psoriasis mouse model. Analysis of human psoriatic skin biopsies shows positive correlation between PGE2 signaling and the IL-23/Th17 pathway.
Project description:The discovery of immune checkpoint inhibitor (ICI) has highlighted the clinical importance of immune evasion in cancer. However, only a fraction of cancer patients show response to ICI, raising a question on immune suppression mechanisms other than immune checkpoint. In this study, we examined the role of the lipid inflammatory mediator PGE2 in immune evasion of the ICI-insensitive Lewis Lung Carcinoma line 1 (LLC1) mouse model. Inhibition of PGE receptors, EP2 and EP4, significantly suppressed tumor growth through the modulation of host immune cells. Single cell RNA-sequencing analysis revealed that EP2/4 inhibition elicited anti-tumor immunity through the reprogramming of inflammatory myeloid cells by downregulating expression of genes in NFB signaling and actions and suppression of the mregDC-regulatory T cell axis by downregulating genes associated with regulatory T cell recruitment and activation. Taken together, our work suggests that PGE2-EP2/EP4 signaling induces proinflammatory myeloid and tolerogenic lymphoid environments in ICI-insensitive tumors, which is amenable to EP2 and EP4 inhibitors..
Project description:ATAC sequencing was used to determine the impact of PGE2 signaling on NK cell function. Our analysis revealed that PGE2 induces a dysfunctional program in NK cells characterized by the inability to produce cytokines and chemokines upon their activation. Mechanistically, this program is governed by epigenetic changes downstream of the PGE2 receptors EP2 and EP4.
Project description:RNA sequencing was used to determine the impact of PGE2 signaling on NK cell function. Our analysis revealed that PGE2 induces a dysfunctional program in NK cells characterized by the inability to produce cytokines and chemokines upon their activation. Mechanistically, this program is governed by transcriptional changes downstream of the PGE2 receptors EP2 and EP4.
Project description:The cervix represents a formidable structural barrier for successful induction of labor. Approximately 10% of pregnancies undergo induction of cervical ripening and labor with prostaglandin (PG) E2 or PGE analogs, often requiring many hours of hospitalization and monitoring. On the other, preterm cervical ripening in the second trimester predicts preterm birth. The regulatory mechanisms of this paradoxical function of the cervix are unknown. Here, we show that PGE2 utilizes cell-specific EP2 receptor-mediated increases in Ca2+ to dephosphorylate and translocate HDAC4 to the nucleus for repression of 15-hydroxy prostaglandin dehydrogenase (15-PGDH). The crucial role of 15-PGDH in cervical ripening was confirmed in vivo. Although PGE2 or PGDH inhibitor alone did not alter gestational length, treatment with PGDH inhibitor+PGE2 or metabolism-resistant dimethyl-PGE2 resulted in preterm cervical ripening and delivery in mice. The ability of PGE2 to selectively auto-amplify its own concentrations in stromal cells by signaling transcriptional repression of 15-PGDH elucidates long-sought-after molecular mechanisms that govern prostaglandin action in the cervix. This is the first report detailing unique mechanisms of action in the cervix and serves as a catalyst for (i) the use of PGDH inhibitors to initiate, or amplify low-dose PGE2-mediated cervical ripening, or (ii) EP2 receptor antagonists, HDAC4 inhibitors, and 15-PGDH activators to prevent preterm cervical ripening and preterm birth.
Project description:Tumor cell-derived prostaglandin E2 (PGE2) is a tumor cell-intrinsic factor that supports immunosuppression in the tumor microenvironment (TME) by acting on the immune cells, but the impact of PGE2 signaling in tumor cells is unclear. We demonstrate that deleting the PGE2 synthesis enzyme or disrupting autocrine PGE2 signaling through EP4 receptors on tumor cells reverses the T cell-low, myeloid cell-rich TME, activates T cells, and suppresses tumor growth. Mechanistically, Ptges and Ptger4 KO tumor cells exhibited altered T and myeloid cell attractant chemokines, became more susceptible to TNF-a killing, and exhibited reduced adenosine synthesis. Our study reveals an unexpected finding – a non-redundant role for the autocrine mPGES1-PGE2-EP4 signaling axis in pancreatic cancer cells, further nominating mPGES-1 inhibition and EP4 blockade as immune-sensitizing approaches in cancer therapy.
Project description:The Golgi stress response is a homeostatic mechanism that augments the functional capacity of the Golgi apparatus when Golgi function becomes insufficient (Golgi stress). Three response pathways of the Golgi stress response have been identified in mammalian cells, the TFE3, HSP47 and CREB3 pathways, which augment the capacity of specific Golgi functions such as N-glycosylation, anti-apoptotic activity and pro-apoptotic activity, respectively. On the contrary, glycosylation of proteoglycans (PGs) is another important function of the Golgi, although the response pathway upregulating expression of glycosylation enzymes for PGs in response to Golgi stress remains unknown. Here, we found that expression of glycosylation enzymes for PGs was induced upon insufficiency of PG glycosylation capacity in the Golgi (PG-Golgi stress), and that transcriptional induction of genes encoding glycosylation enzymes for PGs was independent of the known Golgi stress response pathways and ER stress response. Promoter analyses of genes encoding these glycosylation enzymes revealed the novel enhancer element PGSE, which regulates their transcriptional induction upon PG-Golgi stress. From these observations, the response pathway we discovered is a novel Golgi stress response pathway, which we have named the PG pathway.
Project description:The Golgi stress response is a homeostatic mechanism that augments the functional capacity of the Golgi apparatus when Golgi function becomes insufficient (Golgi stress). Three response pathways of the Golgi stress response have been identified in mammalian cells, the TFE3, HSP47 and CREB3 pathways, which augment the capacity of specific Golgi functions such as N-glycosylation, anti-apoptotic activity and pro-apoptotic activity, respectively. On the contrary, glycosylation of proteoglycans (PGs) is another important function of the Golgi, although the response pathway upregulating expression of glycosylation enzymes for PGs in response to Golgi stress remains unknown. Here, we found that expression of glycosylation enzymes for PGs was induced upon insufficiency of PG glycosylation capacity in the Golgi (PG-Golgi stress), and that transcriptional induction of genes encoding glycosylation enzymes for PGs was independent of the known Golgi stress response pathways and ER stress response. Promoter analyses of genes encoding these glycosylation enzymes revealed the novel enhancer element PGSE, which regulates their transcriptional induction upon PG-Golgi stress. From these observations, the response pathway we discovered is a novel Golgi stress response pathway, which we have named the PG pathway.