Ceramide and ceramide 1-phosphate in health and disease

Sphingolipids are essential components of cell membranes, and many of them regulate vital cell functions. In particular, ceramide plays crucial roles in cell signaling processes. Two major actions of ceramides are the promotion of cell cycle arrest and the induction of apoptosis. Phosphorylation of ceramide produces ceramide 1-phosphate (C1P), which has opposite effects to ceramide. C1P is mitogenic and has prosurvival properties. In addition, C1P is an important mediator of inflammatory responses, an action that takes place through stimulation of cytosolic phospholipase A2, and the subsequent release of arachidonic acid and prostaglandin formation. All of the former actions are thought to be mediated by intracellularly generated C1P. However, the recent observation that C1P stimulates macrophage chemotaxis implicates specific plasma membrane receptors that are coupled to Gi proteins. Hence, it can be concluded that C1P has dual actions in cells, as it can act as an intracellular second messenger to promote cell survival, or as an extracellular receptor agonist to stimulate cell migration

Phosphatidic Acid Stimulates Lung Cancer Cell Migration through Interaction with the LPA1 Receptor and Subsequent Activation of MAP Kinases and STAT3

Phosphatidic acid (PA) is a key bioactive glycerophospholipid that is implicated in the regulation of vital cell functions such as cell growth, differentiation, and migration, and is involved in a variety of pathologic processes. However, the molecular mechanisms by which PA exerts its pathophysiological actions are incompletely understood. In the present work, we demonstrate that PA stimulates the migration of the human non-small cell lung cancer (NSCLC) A549 adenocarcinoma cells, as determined by the transwell migration assay. PA induced the rapid phosphorylation of mitogen-activated protein kinases (MAPKs) ERK1-2, p38, and JNK, and the pretreatment of cells with selective inhibitors of these kinases blocked the PA-stimulated migration of cancer cells. In addition, the chemotactic effect of PA was inhibited by preincubating the cells with pertussis toxin (PTX), a Gi protein inhibitor, suggesting the implication of a Gi protein-coupled receptor in this action. Noteworthy, a blockade of LPA receptor 1 (LPA1) with the specific LPA1 antagonist AM966, or with the selective LPA1 inhibitors Ki1645 or VPC32193, abolished PA-stimulated cell migration. Moreover, PA stimulated the phosphorylation of the transcription factor STAT3 downstream of JAK2, and inhibitors of either JAK2 or STAT3 blocked PA-stimulated cell migration. It can be concluded that PA stimulates lung adenocarcinoma cell migration through an interaction with the LPA1 receptor and subsequent activation of the MAPKs ERK1-2, p38, and JNK, and that the JAK2/STAT3 pathway is also important in this process. These findings suggest that targeting PA formation and/or the LPA1 receptor may provide new strategies to reduce malignancy in lung cancer.This work was supported by Grant IT1720-22 from “Departamento de Educación, Viceconsejería de Universidades e Investigación del Gobierno Vasco” (GV/EJ, Basque Country, Spain). N. Presa is the recipient of a fellowship from “Departamento de Educación, Universidades e Investigación del Gobierno Vasco” (GV/EJ, Basque Country, Spain)

Phosphatidic Acid Stimulates Myoblast Proliferation through Interaction with LPA1 and LPA2 Receptors

Phosphatidic acid (PA) is a bioactive phospholipid capable of regulating key biological functions, including neutrophil respiratory burst, chemotaxis, or cell growth and differentiation. However, the mechanisms whereby PA exerts these actions are not completely understood. In this work, we show that PA stimulates myoblast proliferation, as determined by measuring the incorporation of [3H]thymidine into DNA and by staining the cells with crystal violet. PA induced the rapid phosphorylation of Akt and ERK1/2, and pretreatment of the cells with specific small interferin RNA (siRNA) to silence the genes encoding these kinases, or with selective pharmacologic inhibitors, blocked PA-stimulated myoblast proliferation. The mitogenic effects of PA were abolished by the preincubation of the myoblasts with pertussis toxin, a Gi protein inhibitor, suggesting the implication of Gi protein-coupled receptors in this action. Although some of the effects of PA have been associated with its possible conversion to lysoPA (LPA), treatment of the myoblasts with PA for up to 60 min did not produce any significant amount of LPA in these cells. Of interest, pharmacological blockade of the LPA receptors 1 and 2, or specific siRNA to silence the genes encoding these receptors, abolished PA-stimulated myoblast proliferation. Moreover, PA was able to compete with LPA for binding to LPA receptors, suggesting that PA can act as a ligand of LPA receptors. It can be concluded that PA stimulates myoblast proliferation through interaction with LPA1 and LPA2 receptors and the subsequent activation of the PI3K/Akt and MEK/ERK1-2 pathways, independently of LPA formation.This research was funded by ‘Departamento de Educación del Gobierno Vasco (Gasteiz-Vitoria, Basque Country, Spain) grant number IT-1106-16 and ‘Ministerio de Ciencia, Innovación y Universidades (Madrid, Spain) grant number SAF2016-79695-R

Phosphatidic Acid Stimulates Lung Cancer Cell Migration through Interaction with the LPA1 Receptor and Subsequent Activation of MAP Kinases and STAT3

Phosphatidic acid (PA) is a key bioactive glycerophospholipid that is implicated in the regulation of vital cell functions such as cell growth, differentiation, and migration, and is involved in a variety of pathologic processes. However, the molecular mechanisms by which PA exerts its pathophysiological actions are incompletely understood. In the present work, we demonstrate that PA stimulates the migration of the human non-small cell lung cancer (NSCLC) A549 adenocarcinoma cells, as determined by the transwell migration assay. PA induced the rapid phosphorylation of mitogen-activated protein kinases (MAPKs) ERK1-2, p38, and JNK, and the pretreatment of cells with selective inhibitors of these kinases blocked the PA-stimulated migration of cancer cells. In addition, the chemotactic effect of PA was inhibited by preincubating the cells with pertussis toxin (PTX), a Gi protein inhibitor, suggesting the implication of a Gi protein-coupled receptor in this action. Noteworthy, a blockade of LPA receptor 1 (LPA1) with the specific LPA1 antagonist AM966, or with the selective LPA1 inhibitors Ki1645 or VPC32193, abolished PA-stimulated cell migration. Moreover, PA stimulated the phosphorylation of the transcription factor STAT3 downstream of JAK2, and inhibitors of either JAK2 or STAT3 blocked PA-stimulated cell migration. It can be concluded that PA stimulates lung adenocarcinoma cell migration through an interaction with the LPA1 receptor and subsequent activation of the MAPKs ERK1-2, p38, and JNK, and that the JAK2/STAT3 pathway is also important in this process. These findings suggest that targeting PA formation and/or the LPA1 receptor may provide new strategies to reduce malignancy in lung cancer.This work was supported by Grant IT1720-22 from “Departamento de Educación, Viceconsejería de Universidades e Investigación del Gobierno Vasco” (GV/EJ, Basque Country, Spain). N. Presa is the recipient of a fellowship from “Departamento de Educación, Universidades e Investigación del Gobierno Vasco” (GV/EJ, Basque Country, Spain).Peer reviewe