Lysophosphatidic Acid Signalling in Cancer

A special issue of Cancers (ISSN 2072-6694).

Deadline for manuscript submissions: closed (31 March 2022) | Viewed by 54076

Special Issue Editor


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Guest Editor
Signal Transduction Research Group, Cancer Research Institute of Northern Alberta, Department of Biochemistry, Faculty of Medicine and Dentistry, University of Alberta, Edmonton, AB T6G 2S2, Canada
Interests: breast cancer; metastasis; inflammation; chemo-resistance; radiation-induced fibrosis; autotaxin; lysophosphatidic acid; lipid phosphate phosphatases
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Special Issue Information

Dear Colleagues,

It is now just over 25 years since the separate discoveries of autotaxin (ATX) and the role of lysophosphatidic acid (lysophosphatidate, LPA) as a signaling molecule. The identification of six G-protein-coupled receptors for LPA was a major breakthrough in understanding the role of extracellular LPA in cell signaling. The work on ATX and LPA signaling came together about 18 years ago after ATX was identified as the enzyme that produces the majority of extracellular LPA. The other major component of the LPA signaling system is its termination through the degradation of extracellular LPA by a family of three lipid phosphate phosphatases (LPP1–3).

This Special Issue of Cancers will focus specifically on the role of LPA signaling in cancers and their treatments. The net effects of LPA signaling in cancers are increased in various tumors through increased ATX secretion coupled with a decrease in the expression of LPP1 and LPP3. LPA signaling is now being recognized as a central mediator of the progression of chronic inflammation in the tumor microenvironment and a component of several of the hallmarks of cancer. LPA promotes tumor growth and metastasis, and facilitates immune evasion. The role of LPA as a pro-survival signal also explains why LPA decreases the efficacy of several chemotherapeutic agents and also protects cancer cells from cell death caused by ionizing radiation.

There are now a variety of therapeutic agents which inhibit LPA synthesis by ATX, LPA signaling through its receptors, and increase LPA degradation. So far, these have not been used to decrease the adverse effects of LPA signaling in the management of cancer patients. We are now at the exciting point of being able to target LPA signaling as a novel paradigm for improving existing cancer treatments.

Prof. Dr. David Brindley
Guest Editor

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Published Papers (14 papers)

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Editorial

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5 pages, 168 KiB  
Editorial
Lysophosphatidic Acid Signaling in Cancer
by David N. Brindley
Cancers 2020, 12(12), 3791; https://doi.org/10.3390/cancers12123791 - 16 Dec 2020
Cited by 7 | Viewed by 1627
Abstract
This Special Issue aims to highlight the impact of discoveries made over the last 25 years on the role of autotaxin (ATX) and lysophosphatidic acid (lysophosphatidate, LPA) signaling in tumor growth, metastasis and the treatment of cancers by chemotherapy, radiotherapy and immunotherapy [...] [...] Read more.
This Special Issue aims to highlight the impact of discoveries made over the last 25 years on the role of autotaxin (ATX) and lysophosphatidic acid (lysophosphatidate, LPA) signaling in tumor growth, metastasis and the treatment of cancers by chemotherapy, radiotherapy and immunotherapy [...] Full article
(This article belongs to the Special Issue Lysophosphatidic Acid Signalling in Cancer)

Research

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21 pages, 4488 KiB  
Article
Dexamethasone Attenuates X-Ray-Induced Activation of the Autotaxin-Lysophosphatidate-Inflammatory Cycle in Breast Tissue and Subsequent Breast Fibrosis
by Guanmin Meng, Melinda Wuest, Xiaoyun Tang, Jennifer Dufour, Todd P.W. McMullen, Frank Wuest, David Murray and David N. Brindley
Cancers 2020, 12(4), 999; https://doi.org/10.3390/cancers12040999 - 18 Apr 2020
Cited by 13 | Viewed by 2931
Abstract
We recently showed that radiation-induced DNA damage in breast adipose tissue increases autotaxin secretion, production of lysophosphatidate (LPA) and expression of LPA1/2 receptors. We also established that dexamethasone decreases autotaxin production and LPA signaling in non-irradiated adipose tissue. In the present study, [...] Read more.
We recently showed that radiation-induced DNA damage in breast adipose tissue increases autotaxin secretion, production of lysophosphatidate (LPA) and expression of LPA1/2 receptors. We also established that dexamethasone decreases autotaxin production and LPA signaling in non-irradiated adipose tissue. In the present study, we showed that dexamethasone attenuated the radiation-induced increases in autotaxin activity and the concentrations of inflammatory mediators in cultured human adipose tissue. We also exposed a breast fat pad in mice to three daily 7.5 Gy fractions of X-rays. Dexamethasone attenuated radiation-induced increases in autotaxin activity in plasma and mammary adipose tissue and LPA1 receptor levels in adipose tissue after 48 h. DEX treatment during five daily fractions of 7.5 Gy attenuated fibrosis by ~70% in the mammary fat pad and underlying lungs at 7 weeks after radiotherapy. This was accompanied by decreases in CXCL2, active TGF-β1, CTGF and Nrf2 at 7 weeks in adipose tissue of dexamethasone-treated mice. Autotaxin was located at the sites of fibrosis in breast tissue and in the underlying lungs. Consequently, our work supports the premise that increased autotaxin production and lysophosphatidate signaling contribute to radiotherapy-induced breast fibrosis and that dexamethasone attenuated the development of fibrosis in part by blocking this process. Full article
(This article belongs to the Special Issue Lysophosphatidic Acid Signalling in Cancer)
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22 pages, 3112 KiB  
Article
Repeated Fractions of X-Radiation to the Breast Fat Pads of Mice Augment Activation of the Autotaxin-Lysophosphatidate-Inflammatory Cycle
by Guanmin Meng, Melinda Wuest, Xiaoyun Tang, Jennifer Dufour, YuanYuan Zhao, Jonathan M. Curtis, Todd P. W. McMullen, David Murray, Frank Wuest and David N. Brindley
Cancers 2019, 11(11), 1816; https://doi.org/10.3390/cancers11111816 - 19 Nov 2019
Cited by 15 | Viewed by 2842
Abstract
Breast cancer patients are usually treated with multiple fractions of radiotherapy (RT) to the whole breast after lumpectomy. We hypothesized that repeated fractions of RT would progressively activate the autotaxin–lysophosphatidate-inflammatory cycle. To test this, a normal breast fat pad and a fat pad [...] Read more.
Breast cancer patients are usually treated with multiple fractions of radiotherapy (RT) to the whole breast after lumpectomy. We hypothesized that repeated fractions of RT would progressively activate the autotaxin–lysophosphatidate-inflammatory cycle. To test this, a normal breast fat pad and a fat pad containing a mouse 4T1 tumor were irradiated with X-rays using a small-animal “image-guided” RT platform. A single RT dose of 7.5 Gy and three daily doses of 7.5 Gy increased ATX activity and decreased plasma adiponectin concentrations. The concentrations of IL-6 and TNFα in plasma and of VEGF, G-CSF, CCL11 and CXCL10 in the irradiated fat pad were increased, but only after three fractions of RT. In 4T1 breast tumor-bearing mice, three fractions of 7.5 Gy augmented tumor-induced increases in plasma ATX activity and decreased adiponectin levels in the tumor-associated mammary fat pad. There were also increased expressions of multiple inflammatory mediators in the tumor-associated mammary fat pad and in tumors, which was accompanied by increased infiltration of CD45+ leukocytes into tumor-associated adipose tissue. This work provides novel evidence that increased ATX production is an early response to RT and that repeated fractions of RT activate the autotaxin–lysophosphatidate-inflammatory cycle. This wound healing response to RT-induced damage could decrease the efficacy of further fractions of RT. Full article
(This article belongs to the Special Issue Lysophosphatidic Acid Signalling in Cancer)
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19 pages, 3216 KiB  
Article
Hypoxia Downregulates LPP3 and Promotes the Spatial Segregation of ATX and LPP1 During Cancer Cell Invasion
by Kelly Harper, Karine Brochu-Gaudreau, Caroline Saucier and Claire M. Dubois
Cancers 2019, 11(9), 1403; https://doi.org/10.3390/cancers11091403 - 19 Sep 2019
Cited by 11 | Viewed by 3851
Abstract
Hypoxia is a common characteristic of advanced solid tumors and a potent driver of tumor invasion and metastasis. Recent evidence suggests the involvement of autotaxin (ATX) and lysophosphatidic acid receptors (LPARs) in cancer cell invasion promoted by the hypoxic tumor microenvironment; however, the [...] Read more.
Hypoxia is a common characteristic of advanced solid tumors and a potent driver of tumor invasion and metastasis. Recent evidence suggests the involvement of autotaxin (ATX) and lysophosphatidic acid receptors (LPARs) in cancer cell invasion promoted by the hypoxic tumor microenvironment; however, the transcriptional and/or spatiotemporal control of this process remain unexplored. Herein, we investigated whether hypoxia promotes cell invasion by affecting the main enzymes involved in its production (ATX) and degradation (lipid phosphate phosphatases, LPP1 and LPP3). We report that hypoxia not only modulates the expression levels of lysophosphatidic acid (LPA) regulatory enzymes but also induces their significant spatial segregation in a variety of cancers. While LPP3 expression was downregulated by hypoxia, ATX and LPP1 were asymmetrically redistributed to the leading edge and to the trailing edge, respectively. This was associated with the opposing roles of ATX and LPPs in cell invasion. The regulated expression and compartmentalization of these enzymes of opposing function can provide an effective way to control the generation of an LPA gradient that drives cellular invasion and migration in the hypoxic zones of tumors. Full article
(This article belongs to the Special Issue Lysophosphatidic Acid Signalling in Cancer)
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13 pages, 1504 KiB  
Article
Challenges and Inconsistencies in Using Lysophosphatidic Acid as a Biomarker for Ovarian Cancer
by Tsukasa Yagi, Muhammad Shoaib, Cyrus E. Kuschner, Mitsuaki Nishikimi, Lance B. Becker, Annette T. Lee and Junhwan Kim
Cancers 2019, 11(4), 520; https://doi.org/10.3390/cancers11040520 - 11 Apr 2019
Cited by 21 | Viewed by 3164
Abstract
Increased detection of plasma lysophosphatidic acid (LPA) has been proposed as a potential diagnostic biomarker in ovarian cancer, but inconsistency exists in these reports. It has been shown that LPA can undergo an artificial increase during sample processing and analysis, which has not [...] Read more.
Increased detection of plasma lysophosphatidic acid (LPA) has been proposed as a potential diagnostic biomarker in ovarian cancer, but inconsistency exists in these reports. It has been shown that LPA can undergo an artificial increase during sample processing and analysis, which has not been accounted for in ovarian cancer research. The aim of this study is to provide a potential explanation about how the artificial increase in LPA may have interfered with previous LPA analysis in ovarian cancer research. Using an established LC-MS method, we measured LPA and other lysophospholipid levels in plasma obtained from three cohorts of patients: non-cancer controls, patients with benign ovarian tumors, and those with ovarian cancer. We did not find the LPA level to be higher in cancer samples. To understand this inconsistency, we observed that LPA content changed more significantly than other lysophospholipids as a function of plasma storage time while frozen. Additionally, only LPA was found to be adversely impacted by incubation time depending on the Ethylenediaminetetraacetic acid (EDTA) concentration used during blood drawing. We also show that the inhibition of autotaxin effectively prevented artificial LPA generation during incubation at room temperature. Our data suggests that the artificial changes in LPA content may contribute to the discrepancies reported in literature. Any future studies planning to measure plasma LPA should carefully design the study protocol to consider these confounding factors. Full article
(This article belongs to the Special Issue Lysophosphatidic Acid Signalling in Cancer)
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Review

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20 pages, 2173 KiB  
Review
Regulation of Tumor Immunity by Lysophosphatidic Acid
by Sue Chin Lee, Mélanie A. Dacheux, Derek D. Norman, Louisa Balázs, Raul M. Torres, Corinne E. Augelli-Szafran and Gábor J. Tigyi
Cancers 2020, 12(5), 1202; https://doi.org/10.3390/cancers12051202 - 10 May 2020
Cited by 30 | Viewed by 4929
Abstract
The tumor microenvironment (TME) may be best conceptualized as an ecosystem comprised of cancer cells interacting with a multitude of stromal components such as the extracellular matrix (ECM), blood and lymphatic networks, fibroblasts, adipocytes, and cells of the immune system. At the center [...] Read more.
The tumor microenvironment (TME) may be best conceptualized as an ecosystem comprised of cancer cells interacting with a multitude of stromal components such as the extracellular matrix (ECM), blood and lymphatic networks, fibroblasts, adipocytes, and cells of the immune system. At the center of this crosstalk between cancer cells and their TME is the bioactive lipid lysophosphatidic acid (LPA). High levels of LPA and the enzyme generating it, termed autotaxin (ATX), are present in many cancers. It is also well documented that LPA drives tumor progression by promoting angiogenesis, proliferation, survival, invasion and metastasis. One of the hallmarks of cancer is the ability to modulate and escape immune detection and eradication. Despite the profound role of LPA in regulating immune functions and inflammation, its role in the context of tumor immunity has not received much attention until recently where emerging studies highlight that this signaling axis may be a means that cancer cells adopt to evade immune detection and eradication. The present review aims to look at the immunomodulatory actions of LPA in baseline immunity to provide a broad understanding of the subject with a special emphasis on LPA and cancer immunity, highlighting the latest progress in this area of research. Full article
(This article belongs to the Special Issue Lysophosphatidic Acid Signalling in Cancer)
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18 pages, 3097 KiB  
Review
Autotaxin and Breast Cancer: Towards Overcoming Treatment Barriers and Sequelae
by Matthew G. K. Benesch, Xiaoyun Tang and David N. Brindley
Cancers 2020, 12(2), 374; https://doi.org/10.3390/cancers12020374 - 06 Feb 2020
Cited by 29 | Viewed by 3719
Abstract
After a decade of intense preclinical investigations, the first in-class autotaxin inhibitor, GLPG1690, has entered Phase III clinical trials for idiopathic pulmonary fibrosis. In the intervening time, a deeper understanding of the role of the autotaxin–lysophosphatidate (LPA)–lipid phosphate phosphatase axis in breast cancer [...] Read more.
After a decade of intense preclinical investigations, the first in-class autotaxin inhibitor, GLPG1690, has entered Phase III clinical trials for idiopathic pulmonary fibrosis. In the intervening time, a deeper understanding of the role of the autotaxin–lysophosphatidate (LPA)–lipid phosphate phosphatase axis in breast cancer progression and treatment resistance has emerged. Concordantly, appreciation of the tumor microenvironment and chronic inflammation in cancer biology has matured. The role of LPA as a central mediator behind these concepts has been exemplified within the breast cancer field. In this review, we will summarize current challenges in breast cancer therapy and delineate how blocking LPA signaling could provide novel adjuvant therapeutic options for overcoming therapy resistance and adverse side effects, including radiation-induced fibrosis. The advent of autotaxin inhibitors in clinical practice could herald their applications as adjuvant therapies to improve the therapeutic indexes of existing treatments for breast and other cancers. Full article
(This article belongs to the Special Issue Lysophosphatidic Acid Signalling in Cancer)
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15 pages, 1548 KiB  
Review
Autotaxin Implication in Cancer Metastasis and Autoimunne Disorders: Functional Implication of Binding Autotaxin to the Cell Surface
by Olivier Peyruchaud, Lou Saier and Raphaël Leblanc
Cancers 2020, 12(1), 105; https://doi.org/10.3390/cancers12010105 - 31 Dec 2019
Cited by 26 | Viewed by 4190
Abstract
Autotaxin (ATX) is an exoenzyme which, due to its unique lysophospholipase D activity, is responsible for the synthesis of lysophosphatidic acid (LPA). ATX activity is responsible for the concentration of LPA in the blood. ATX expression is increased in various types of cancers, [...] Read more.
Autotaxin (ATX) is an exoenzyme which, due to its unique lysophospholipase D activity, is responsible for the synthesis of lysophosphatidic acid (LPA). ATX activity is responsible for the concentration of LPA in the blood. ATX expression is increased in various types of cancers, including breast cancer, where it promotes metastasis. The expression of ATX is also remarkably increased under inflammatory conditions, particularly in the osteoarticular compartment, where it controls bone erosion. Biological actions of ATX are mediated by LPA. However, the phosphate head group of LPA is highly sensitive to degradation by the action of lipid phosphate phosphatases, resulting in LPA inactivation. This suggests that for efficient action, LPA requires protection, which is potentially achieved through docking to a carrier protein. Interestingly, recent reports suggest that ATX might act as a docking molecule for LPA and also support the concept that binding of ATX to the cell surface through its interaction with adhesive molecules (integrins, heparan sulfate proteoglycans) could facilitate a rapid route of delivering active LPA to its cell surface receptors. This new mechanism offers a new vision of how ATX/LPA works in cancer metastasis and inflammatory bone diseases, paving the way for new therapeutic developments. Full article
(This article belongs to the Special Issue Lysophosphatidic Acid Signalling in Cancer)
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14 pages, 1119 KiB  
Review
Elevated Autotaxin and LPA Levels during Chronic Viral Hepatitis and Hepatocellular Carcinoma Associate with Systemic Immune Activation
by Lenche Kostadinova, Carey L Shive and Donald D Anthony
Cancers 2019, 11(12), 1867; https://doi.org/10.3390/cancers11121867 - 25 Nov 2019
Cited by 13 | Viewed by 2945
Abstract
Circulating autotaxin (ATX) is elevated in persons with liver disease, particularly in the setting of chronic hepatitis C virus (HCV) and HCV/HIV infection. It is thought that plasma ATX levels are, in part, attributable to impaired liver clearance that is secondary to fibrotic [...] Read more.
Circulating autotaxin (ATX) is elevated in persons with liver disease, particularly in the setting of chronic hepatitis C virus (HCV) and HCV/HIV infection. It is thought that plasma ATX levels are, in part, attributable to impaired liver clearance that is secondary to fibrotic liver disease. In a discovery data set, we identified plasma ATX to be associated with parameters of systemic immune activation during chronic HCV and HCV/HIV infection. We and others have observed a partial normalization of ATX levels within months of starting interferon-free direct-acting antiviral (DAA) HCV therapy, consistent with a non-fibrotic liver disease contribution to elevated ATX levels, or HCV-mediated hepatocyte activation. Relationships between ATX, lysophosphatidic acid (LPA) and parameters of systemic immune activation will be discussed in the context of HCV infection, age, immune health, liver health, and hepatocellular carcinoma (HCC). Full article
(This article belongs to the Special Issue Lysophosphatidic Acid Signalling in Cancer)
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30 pages, 1893 KiB  
Review
Deregulated Lysophosphatidic Acid Metabolism and Signaling in Liver Cancer
by Eleanna Kaffe, Christiana Magkrioti and Vassilis Aidinis
Cancers 2019, 11(11), 1626; https://doi.org/10.3390/cancers11111626 - 23 Oct 2019
Cited by 37 | Viewed by 6001
Abstract
Liver cancer is one of the leading causes of death worldwide due to late diagnosis and scarcity of treatment options. The major risk factor for liver cancer is cirrhosis with the underlying causes of cirrhosis being viral infection (hepatitis B or C), metabolic [...] Read more.
Liver cancer is one of the leading causes of death worldwide due to late diagnosis and scarcity of treatment options. The major risk factor for liver cancer is cirrhosis with the underlying causes of cirrhosis being viral infection (hepatitis B or C), metabolic deregulation (Non-alcoholic fatty liver disease (NAFLD) in the presence of obesity and diabetes), alcohol or cholestatic disorders. Lysophosphatidic acid (LPA) is a bioactive phospholipid with numerous effects, most of them compatible with the hallmarks of cancer (proliferation, migration, invasion, survival, evasion of apoptosis, deregulated metabolism, neoangiogenesis, etc.). Autotaxin (ATX) is the enzyme responsible for the bulk of extracellular LPA production, and together with LPA signaling is involved in chronic inflammatory diseases, fibrosis and cancer. This review discusses the most important findings and the mechanisms related to ATX/LPA/LPAR involvement on metabolic, viral and cholestatic liver disorders and their progression to liver cancer in the context of human patients and mouse models. It focuses on the role of ATX/LPA in NAFLD development and its progression to liver cancer as NAFLD has an increasing incidence which is associated with the increasing incidence of liver cancer. Bearing in mind that adipose tissue accounts for the largest amount of LPA production, many studies have implicated LPA in adipose tissue metabolism and inflammation, liver steatosis, insulin resistance, glucose intolerance and lipogenesis. At the same time, LPA and ATX play crucial roles in fibrotic diseases. Given that hepatocellular carcinoma (HCC) is usually developed on the background of liver fibrosis, therapies that both delay the progression of fibrosis and prevent its development to malignancy would be very promising. Therefore, ATX/LPA signaling appears as an attractive therapeutic target as evidenced by the fact that it is involved in both liver fibrosis progression and liver cancer development. Full article
(This article belongs to the Special Issue Lysophosphatidic Acid Signalling in Cancer)
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17 pages, 8350 KiB  
Review
The Structural Binding Mode of the Four Autotaxin Inhibitor Types that Differentially Affect Catalytic and Non-Catalytic Functions
by Fernando Salgado-Polo and Anastassis Perrakis
Cancers 2019, 11(10), 1577; https://doi.org/10.3390/cancers11101577 - 16 Oct 2019
Cited by 23 | Viewed by 4783
Abstract
Autotaxin (ATX) is a secreted lysophospholipase D, catalysing the conversion of lysophosphatidylcholine (LPC) to bioactive lysophosphatidic acid (LPA). LPA acts through two families of G protein-coupled receptors (GPCRs) controlling key cellular responses, and it is implicated in many physiological processes and pathologies. ATX, [...] Read more.
Autotaxin (ATX) is a secreted lysophospholipase D, catalysing the conversion of lysophosphatidylcholine (LPC) to bioactive lysophosphatidic acid (LPA). LPA acts through two families of G protein-coupled receptors (GPCRs) controlling key cellular responses, and it is implicated in many physiological processes and pathologies. ATX, therefore, has been established as an important drug target in the pharmaceutical industry. Structural and biochemical studies of ATX have shown that it has a bimetallic nucleophilic catalytic site, a substrate-binding (orthosteric) hydrophobic pocket that accommodates the lipid alkyl chain, and an allosteric tunnel that can accommodate various steroids and LPA. In this review, first, we revisit what is known about ATX-mediated catalysis, crucially in light of allosteric regulation. Then, we present the known ATX catalysis-independent functions, including binding to cell surface integrins and proteoglycans. Next, we analyse all crystal structures of ATX bound to inhibitors and present them based on the four inhibitor types that are established based on the binding to the orthosteric and/or the allosteric site. Finally, in light of these data we discuss how mechanistic differences might differentially modulate the activity of the ATX-LPA signalling axis, and clinical applications including cancer. Full article
(This article belongs to the Special Issue Lysophosphatidic Acid Signalling in Cancer)
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26 pages, 1383 KiB  
Review
Targeting Lysophosphatidic Acid in Cancer: The Issues in Moving from Bench to Bedside
by Yan Xu
Cancers 2019, 11(10), 1523; https://doi.org/10.3390/cancers11101523 - 10 Oct 2019
Cited by 39 | Viewed by 5023
Abstract
Since the clear demonstration of lysophosphatidic acid (LPA)’s pathological roles in cancer in the mid-1990s, more than 1000 papers relating LPA to various types of cancer were published. Through these studies, LPA was established as a target for cancer. Although LPA-related inhibitors entered [...] Read more.
Since the clear demonstration of lysophosphatidic acid (LPA)’s pathological roles in cancer in the mid-1990s, more than 1000 papers relating LPA to various types of cancer were published. Through these studies, LPA was established as a target for cancer. Although LPA-related inhibitors entered clinical trials for fibrosis, the concept of targeting LPA is yet to be moved to clinical cancer treatment. The major challenges that we are facing in moving LPA application from bench to bedside include the intrinsic and complicated metabolic, functional, and signaling properties of LPA, as well as technical issues, which are discussed in this review. Potential strategies and perspectives to improve the translational progress are suggested. Despite these challenges, we are optimistic that LPA blockage, particularly in combination with other agents, is on the horizon to be incorporated into clinical applications. Full article
(This article belongs to the Special Issue Lysophosphatidic Acid Signalling in Cancer)
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14 pages, 1115 KiB  
Review
MicroRNA Regulation of the Autotaxin-Lysophosphatidic Acid Signaling Axis
by Mandi M. Murph
Cancers 2019, 11(9), 1369; https://doi.org/10.3390/cancers11091369 - 14 Sep 2019
Cited by 8 | Viewed by 3110
Abstract
The revelation that microRNAs (miRNAs) exist within the human genome uncovered an underappreciated mechanism of gene expression. For cells to regulate expression of their genes, miRNA molecules and argonaute proteins bind to mRNAs and interfere with efficient translation of the RNA transcript. Although [...] Read more.
The revelation that microRNAs (miRNAs) exist within the human genome uncovered an underappreciated mechanism of gene expression. For cells to regulate expression of their genes, miRNA molecules and argonaute proteins bind to mRNAs and interfere with efficient translation of the RNA transcript. Although miRNAs have important roles in normal tissues, miRNAs may adopt aberrant functions in malignant cells depending on their classification as either a tumor suppressor or oncogenic miRNA. Within this review, the current status of miRNA regulation is described in the context of signaling through the lysophosphatidic acid receptors, including the lysophosphatidic acid-producing enzyme, autotaxin. Thus far, research has revealed miRNAs that increase in response to lysophosphatidic acid stimulation, such as miR-21, miR-30c-2-3p, and miR-122. Other miRNAs inhibit the translation of lysophosphatidic acid receptors, such as miR-15b, miR-23a, and miR200c, or proteins that are downstream of lysophosphatidic acid signaling, such as miR-146 and miR-21. With thousands of miRNAs still uncharacterized, it is anticipated that the complex regulation of lysophosphatidic acid signaling by miRNAs will continue to be elucidated. RNA-based therapeutics have entered the clinic with enormous potential in precision medicine. This exciting field is rapidly emerging and it will be fascinating to witness its expansion in scope. Full article
(This article belongs to the Special Issue Lysophosphatidic Acid Signalling in Cancer)
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19 pages, 440 KiB  
Review
Lysophosphatidic Acid and Autotaxin-associated Effects on the Initiation and Progression of Colorectal Cancer
by C. Chris Yun
Cancers 2019, 11(7), 958; https://doi.org/10.3390/cancers11070958 - 09 Jul 2019
Cited by 21 | Viewed by 3879
Abstract
The intestinal epithelium interacts dynamically with the immune system to maintain its barrier function to protect the host, while performing the physiological roles in absorption of nutrients, electrolytes, water and minerals. The importance of lysophosphatidic acid (LPA) and its receptors in the gut [...] Read more.
The intestinal epithelium interacts dynamically with the immune system to maintain its barrier function to protect the host, while performing the physiological roles in absorption of nutrients, electrolytes, water and minerals. The importance of lysophosphatidic acid (LPA) and its receptors in the gut has been progressively appreciated. LPA signaling modulates cell proliferation, invasion, adhesion, angiogenesis, and survival that can promote cancer growth and metastasis. These effects are equally important for the maintenance of the epithelial barrier in the gut, which forms the first line of defense against the milieu of potentially pathogenic stimuli. This review focuses on the LPA-mediated signaling that potentially contributes to inflammation and tumor formation in the gastrointestinal tract. Full article
(This article belongs to the Special Issue Lysophosphatidic Acid Signalling in Cancer)
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