LPA Induces Colon Cancer Cell Proliferation through a Cooperation between the ROCK and STAT-3 Pathways

Roles of lysophosphatidic acid (LPA) receptor-mediated signaling in cancer cell biology

Lysophosphatidic acid (LPA) is a simple lipid which is endogenously synthesized from lysophosphatidylcholine (LPC) by autotaxin (ATX). LPA mediates a variety of cellular responses through the binding of G protein-coupled LPA receptors (LPA1 to LPA6). It is considered that LPA receptor-mediated signaling plays an important role in the pathogenesis of human malignancy. Genetic alterations and epigenetic changes of LPA receptors have been detected in some cancer cells as well as LPA per se. Moreover, LPA receptors contribute to the promotion of tumor progression, including cell proliferation, invasion, metastasis, tumorigenicity, and angiogenesis. In recent studies, the activation of LPA receptor-mediated signaling regulates chemoresistance and radiosensitivity in cancer cells. This review provides an updated overview on the roles of LPA receptor-mediated signaling in the regulation of cancer cell functions and its potential utility as a molecular target for novel therapies in clinical cancer approaches.

Male-Biased Gut Microbiome and Metabolites Aggravate Colorectal Cancer Development

Men demonstrate higher incidence and mortality rates of colorectal cancer (CRC) than women. This study aims to explain the potential causes of such sexual dimorphism in CRC from the perspective of sex-biased gut microbiota and metabolites. The results show that sexual dimorphism in colorectal tumorigenesis is observed in both ApcMin/ + mice and azoxymethane (AOM)/dextran sulfate sodium (DSS)-treated mice with male mice have significantly larger and more tumors, accompanied by more impaired gut barrier function. Moreover, pseudo-germ mice receiving fecal samples from male mice or patients show more severe intestinal barrier damage and higher level of inflammation. A significant change in gut microbiota composition is found with increased pathogenic bacteria Akkermansia muciniphila and deplets probiotic Parabacteroides goldsteinii in both male mice and pseudo-germ mice receiving fecal sample from male mice. Sex-biased gut metabolites in pseudo-germ mice receiving fecal sample from CRC patients or CRC mice contribute to sex dimorphism in CRC tumorigenesis through glycerophospholipids metabolism pathway. Sexual dimorphism in tumorigenesis of CRC mouse models. In conclusion, the sex-biased gut microbiome and metabolites contribute to sexual dimorphism in CRC. Modulating sex-biased gut microbiota and metabolites could be a potential sex-targeting therapeutic strategy of CRC.

LncRNA IUR Is Downregulated in Gastric Carcinoma and Associated with Poor Survival

Objective: LncRNA IUR has been recently identified as a key regulator of Bcr-Abl-induced tumorigenesis, while its role in gastric carcinoma (GC) is unknown. This study investigated the involvement of IUR in GC. Materials and Methods: Gene expression levels were measured by performing quantitative polymerase chain reaction. Interactions between IUR and ROCK1 were analyzed by transfection experiments. Cell invasion and migration were analyzed by Transwell assay. Results: In this study, the authors showed that IUR was downregulated in GC. A follow-up study showed that low IUR expression levels predicted poor survival. In GC tissues, ROCK1 was upregulated in GC tissues and inversely correlated with IUR. In GC cells, IUR overexpression mediated the downregulation of ROCK1. ROCK1 overexpression resulted in increased GC cell invasion and migration, while IUR overexpression played an opposite role. Conclusion: IUR is downregulated in GC and inhibits GC cell invasion and migration by downregulating ROCK1.

Hypoxia increases cellular levels of phosphatidic acid and lysophospholipids in undifferentiated Caco-2 cells

Cancer cells are known to survive in a hypoxic microenvironment by altering their lipid metabolism as well as their energy metabolism. In this study, Caco-2 cells derived from human colon cancer, were found to have elevated intracellular levels of phosphatidic acid and its lysoform, lysophosphatidic acid (LPA), under hypoxic conditions. Our results suggested that the elevation of LPA in Caco-2 cells was mainly due to the combined increases in cellular levels of lysophosphatidylcholine and lysophosphatidylethanolamine by phospholipase A₂ and subsequent hydrolysis to LPA by lysophospholipase D. We detected the Ca²⁺ -stimulated choline-producing activities toward exogenous lysophosphatidylcholines in whole Caco-2 cell homogenates, indicating their involvement in the LPA production in intact Caco-2 cells.

MetaProD: A Highly-Configurable Mass Spectrometry Analyzer for Multiplexed Proteomic and Metaproteomic Data

The microbiome has been shown to be important for human health because of its influence on disease and the immune response. Mass spectrometry is an important tool for evaluating protein expression and species composition in the microbiome but is technically challenging and time-consuming. Multiplexing has emerged as a way to make spectrometry workflows faster while improving results. Here, we present MetaProD (MetaProteomics in Django) as a highly configurable metaproteomic data analysis pipeline supporting label-free and multiplexed mass spectrometry. The pipeline is open-source, uses fully open-source tools, and is integrated with Django to offer a web-based interface for configuration and data access. Benchmarking of MetaProD using multiple metaproteomics data sets showed that MetaProD achieved fast and efficient identification of peptides and proteins. Application of MetaProD to a multiplexed cancer data set resulted in identification of more differentially expressed human proteins in cancer tissues versus healthy tissues as compared to previous studies; in addition, MetaProD identified bacterial proteins in those samples, some of which are differentially abundant.

Lysophosphatidic Acid Signaling and microRNAs: New Roles in Various Cancers

A wide range of microRNAs (miRNAs) are coded for in the human genome and contribute to the regulation of gene expression. MiRNAs are able to degrade mRNAs and/or prevent the RNA transcript from being translated through complementary binding of the miRNA seed region (nucleotide 2-8) to the 3’-untranslated regions of many mRNAs. Although miRNAs are involved in almost all processes of normal human cells, they are also involved in the abnormal functions of cancer cells. MiRNAs can play dual regulatory roles in cancer, acting either as tumor suppressors or as tumor promoters, depending on the target, tumor type, and stage. In the current review, we discuss the present status of miRNA modulation in the setting of lysophosphatidic acid (LPA) signaling. LPA is produced from lysophosphatidylcholine by the enzyme autotaxin and signals via a range of G protein-coupled receptors to affect cellular processes, which ultimately causes changes in cell morphology, survival, proliferation, differentiation, migration, and adhesion. Several studies have identified miRNAs that are over-expressed in response to stimulation by LPA, but their functional roles have not yet been fully clarified. Since RNA-based treatments hold tremendous promise in the area of personalized medicne, many efforts have been made to bring miRNAs into clinical trials, and this field is evolving at an increasing pace.

Targeting lysophosphatidic acid receptor with Ki16425 impedes T cell lymphoma progression through apoptosis induction, glycolysis inhibition, and activation of antitumor immune response

Lysophosphatidic acid (LPA) is a small phospholipid that acts as an extracellular lipid mediator. It promotes cancer progression by altering a wide array of cellular processes, including apoptosis, survival, angiogenesis, invasion, and migration through binding with its cognate receptors. Intriguingly, our previous study showed that in vitro treatment of LPA induced survival of T lymphoma cells. Hence, the present investigation was designed to investigate the antitumor potential of Ki16425, an antagonist of LPA receptors, against T cell lymphoma. Our in vitro results showed inhibition of LPA-mediated survival and metabolic activity of T lymphoma cells by Ki16425. Further, in vivo experimental findings indicated the tumor retarding potential of Ki16425 against T cell lymphoma through apoptosis induction, glycolysis inhibition, and immunoactivation. The administration of Ki16425 triggered apoptosis by down-regulating the expression of Bcl2 and up-regulating p53, Bax, cleaved caspase-3, and Cyt c expression. Further, Ki16425 suppressed glycolytic activity with concomitantly decreased expression of GLUT3 and MCT1. Moreover, we also noticed an elevated level of NO and iNOS in tumor cells after Ki16425 administration which might also be responsible for apoptosis induction and suppressed glycolysis. Additionally, we observed an increased population of total leukocytes, lymphocytes, and monocytes along with increased thymocytes count and IL-2 and IFN-γ levels. Besides, we observed amelioration of tumor-induced kidney and liver damages by Ki16425. Taken together, this is the first study that demonstrates that LPA receptors could be potential future therapeutic targets for designing promising therapeutic strategies against T cell lymphoma.

Loss of TIPE3 reduced the proliferation, survival and migration of lung cancer cells through inactivation of Akt/mTOR, NF-κB, STAT-3 signaling cascade

Lung cancer is the foremost cause of cancer related mortality among men and one of the most fatal cancers among women. Notably, the 5-year survival rate of lung cancer is very less; 5% in developing countries. This low survival rate can be attributed to factors like late stage diagnosis, rapid postoperative recurrences in the patients undergoing treatment and development of chemoresistance against different agents used for treating lung cancer. Therefore, in this study we evaluated the potential of a recently identified protein namely TIPE3 which is known as a transfer protein of lipid second messengers as a lung cancer biomarker. TIPE3 was found to be significantly upregulated in lung cancer tissues indicating its role in the positive regulation of lung cancer. Supporting this finding, knockout of TIPE3 was also found to reduce the proliferation, survival and migration of lung cancer cells and arrested the G2 phase of cell cycle through inactivation of Akt/mTOR, NF-κB, STAT-3 signaling. It is well evinced that tobacco is the major risk factor of lung cancer which affects both males and females. Therefore, this study also evaluated the involvement of TIPE3 in tobacco mediated lung carcinogenesis. Notably, this study shows for the first time that TIPE3 positively regulates tobacco induced proliferation, survival and migration of lung cancer through modulation of Akt/mTOR signaling. Thus, TIPE3 plays critical role in the pathogenesis of lung cancer and hence it can be specifically targeted to develop novel therapeutic strategies.

G6PD upregulates Cyclin E1 and MMP9 to promote clear cell renal cell carcinoma progression

Background: Clear cell renal cell carcinoma (ccRCC) is a cell metabolic disease with high metastasis rate and poor prognosis. Our previous studies demonstrate that glucose-6-phosphate dehydrogenase (G6PD), the first and rate-limiting enzyme of the pentose phosphate pathway, is highly expressed in ccRCC and predicts poor outcomes of ccRCC patients. The aims of this study were to confirm the oncogenic role of G6PD in ccRCC and unravels novel mechanisms involving Cyclin E1 and MMP9 in G6PD-mediated ccRCC progression. Methods: Real-time RT-PCR, Western blot and immunohistochemistry were used to determine the expression patterns of G6PD, Cyclin E1 and MMP9 in ccRCC. TCGA dataset mining was used to identify Cyclin E1 and MMP9 correlations with G6PD expression, relationships between clinicopathological characteristics of ccRCC and the genes of interest, as well as the prognosis of ccRCC patients. The role of G6PD in ccRCC progression and the regulatory effect of G6PD on Cyclin E1 and MMP9 expression were investigated by using a series of cytological function assays in vitro. To verify this mechanism in vivo, xenografted mice models were established. Results: G6PD, Cyclin E1 and MMP9 were overexpressed and positively correlated in ccRCC, and they were associated with poor prognosis of ccRCC patients. Moreover, G6PD changed cell cycle dynamics, facilitated cells proliferation, promoted migration in vitro, and enhanced ccRCC development in vivo, more likely through enhancing Cyclin E1 and MMP9 expression. Conclusion: These findings present G6PD, Cyclin E1 and MMP9, which contribute to ccRCC progression, as novel biomarkers and potential therapeutic targets for ccRCC treatment.

Lysophosphatidic Acid Mediates Imiquimod-Induced Psoriasis-like Symptoms by Promoting Keratinocyte Proliferation through LPAR1/ROCK2/PI3K/AKT Signaling Pathway

Psoriasis is a chronic inflammatory skin disease. Recently, lysophosphatidic acid (LPA)/LPAR5 signaling has been reported to be involved in both NLRP3 inflammasome activation in macrophages and keratinocyte activation to produce inflammatory cytokines, contributing to psoriasis pathogenesis. However, the effect and molecular mechanisms of LPA/LPAR signaling in keratinocyte proliferation in psoriasis remain unclear. In this study, we investigated the effects of LPAR1/3 inhibition on imiquimod (IMQ)-induced psoriasis-like mice. Treatment with the LPAR1/3 antagonist, ki16425, alleviated skin symptoms in IMQ-induced psoriasis-like mouse models and decreased keratinocyte proliferation in the lesion. It also decreased LPA-induced cell proliferation and cell cycle progression via increased cyclin A2, cyclin D1, cyclin-dependent kinase (CDK)2, and CDK4 expression and decreased p27^Kip1 expression in HaCaT cells. LPAR1 knockdown in HaCaT cells reduced LPA-induced proliferation, suppressed cyclin A2 and CDK2 expression, and restored p27^Kip1 expression. LPA increased Rho-associated protein kinase 2 (ROCK2) expression and PI3K/AKT activation; moreover, the pharmacological inhibition of ROCK2 and PI3K/AKT signaling suppressed LPA-induced cell cycle progression. In conclusion, we demonstrated that LPAR1/3 antagonist alleviates IMQ-induced psoriasis-like symptoms in mice, and in particular, LPAR1 signaling is involved in cell cycle progression via ROCK2/PI3K/AKT pathways in keratinocytes.

Lysophosphatidic Acid Signaling in Cancer Cells: What Makes LPA So Special?

Lysophosphatidic acid (LPA) refers to a family of simple phospholipids that act as ligands for G protein-coupled receptors. While LPA exerts effects throughout the body in normal physiological circumstances, its pathological role in cancer is of great interest from a therapeutic viewpoint. The numerous LPA receptors (LPARs) are coupled to a variety of G proteins, and more than one LPAR is typically expressed on any given cell. While the individual receptors signal through conventional GPCR pathways, LPA is particularly efficacious in stimulating cancer cell proliferation and migration. This review addresses the mechanistic aspects underlying these pro-tumorigenic effects. We provide examples of LPA signaling responses in various types of cancers, with an emphasis on those where roles have been identified for specific LPARs. While providing an overview of LPAR signaling, these examples also reveal gaps in our knowledge regarding the mechanisms of LPA action at the receptor level. The current understanding of the LPAR structure and the roles of LPAR interactions with other receptors are discussed. Overall, LPARs provide insight into the potential molecular mechanisms that underlie the ability of individual GPCRs (or combinations of GPCRs) to elicit a unique spectrum of responses from their agonist ligands. Further knowledge of these mechanisms will inform drug discovery, since GPCRs are promising therapeutic targets for cancer.

Control of Intestinal Epithelial Permeability by Lysophosphatidic Acid Receptor 5

BACKGROUND & AIMS

Epithelial cells form a monolayer at mucosal surface that functions as a highly selective barrier. Lysophosphatidic acid (LPA) is a bioactive lipid that elicits a broad range of biological effects via cognate G protein-coupled receptors. LPA receptor 5 (LPA₅) is highly expressed in intestinal epithelial cells, but its role in the intestine is not well-known. Here we determined the role of LPA₅ in regulation of intestinal epithelial barrier.

METHODS

Epithelial barrier integrity was determined in mice with intestinal epithelial cell (IEC)-specific LPA₅ deletion, Lpar5^ΔIEC. LPA was orally administered to mice, and intestinal permeability was measured. Dextran sulfate sodium (DSS) was used to induce colitis. Human colonic epithelial cell lines were used to determine the LPA₅-mediated signaling pathways that regulate epithelial barrier.

RESULTS

We observed increased epithelial permeability in Lpar5^ΔIEC mice with reduced claudin-4 expression. Oral administration of LPA decreased intestinal permeability in wild-type mice, but the effect was greatly mitigated in Lpar5^ΔIEC mice. Serum lipopolysaccharide level and bacterial loads in the intestine and liver were elevated in Lpar5^ΔIEC mice. Lpar5^ΔIEC mice developed more severe colitis induced with DSS. LPA₅ transcriptionally regulated claudin-4, and this regulation was dependent on transactivation of the epidermal growth factor receptor, which induced localization of Rac1 at the cell membrane. LPA induced the translocation of Stat3 to the cell membrane and promoted the interaction between Rac1 and Stat3. Inhibition of Stat3 ablated LPA-mediated regulation of claudin-4.

CONCLUSIONS

This study identifies LPA₅ as a regulator of the intestinal barrier. LPA₅ promotes claudin-4 expression in IECs through activation of Rac1 and Stat3.

Unraveling the Molecular Nexus between GPCRs, ERS, and EMT

G protein-coupled receptors (GPCRs) represent a large family of transmembrane proteins that transduce an external stimulus into a variety of cellular responses. They play a critical role in various pathological conditions in humans, including cancer, by regulating a number of key processes involved in tumor formation and progression. The epithelial-mesenchymal transition (EMT) is a fundamental process in promoting cancer cell invasion and tumor dissemination leading to metastasis, an often intractable state of the disease. Uncontrolled proliferation and persistent metabolism of cancer cells also induce oxidative stress, hypoxia, and depletion of growth factors and nutrients. These disturbances lead to the accumulation of misfolded proteins in the endoplasmic reticulum (ER) and induce a cellular condition called ER stress (ERS) which is counteracted by activation of the unfolded protein response (UPR). Many GPCRs modulate ERS and UPR signaling via ERS sensors, IRE1α, PERK, and ATF6, to support cancer cell survival and inhibit cell death. By regulating downstream signaling pathways such as NF-κB, MAPK/ERK, PI3K/AKT, TGF-β, and Wnt/β-catenin, GPCRs also upregulate mesenchymal transcription factors including Snail, ZEB, and Twist superfamilies which regulate cell polarity, cytoskeleton remodeling, migration, and invasion. Likewise, ERS-induced UPR upregulates gene transcription and expression of proteins related to EMT enhancing tumor aggressiveness. Though GPCRs are attractive therapeutic targets in cancer biology, much less is known about their roles in regulating ERS and EMT. Here, we will discuss the interplay in GPCR-ERS linked to the EMT process of cancer cells, with a particular focus on oncogenes and molecular signaling pathways.

Role of lysophosphatidic acid and its receptors in health and disease: novel therapeutic strategies

Lysophosphatidic acid (LPA) is an abundant bioactive phospholipid, with multiple functions both in development and in pathological conditions. Here, we review the literature about the differential signaling of LPA through its specific receptors, which makes this lipid a versatile signaling molecule. This differential signaling is important for understanding how this molecule can have such diverse effects during central nervous system development and angiogenesis; and also, how it can act as a powerful mediator of pathological conditions, such as neuropathic pain, neurodegenerative diseases, and cancer progression. Ultimately, we review the preclinical and clinical uses of Autotaxin, LPA, and its receptors as therapeutic targets, approaching the most recent data of promising molecules modulating both LPA production and signaling. This review aims to summarize the most update knowledge about the mechanisms of LPA production and signaling in order to understand its biological functions in the central nervous system both in health and disease.

Lysophosphatidic Acid Is an Inflammatory Lipid Exploited by Cancers for Immune Evasion via Mechanisms Similar and Distinct From CTLA-4 and PD-1

Immunological tolerance has evolved to curtail immune responses against self-antigens and prevent autoimmunity. One mechanism that contributes to immunological tolerance is the expression of inhibitory receptors by lymphocytes that signal to dampen immune responses during the course of an infection and to prevent immune-mediated collateral damage to the host. The understanding that tumors exploit these physiological mechanisms to avoid elimination has led to remarkable, but limited, success in the treatment of cancer through the use of biologics that interfere with the ability of cancers to suppress immune function. This therapy, based on the understanding of how T lymphocytes are normally activated and suppressed, has led to the development of therapeutic blocking antibodies, referred to as immune checkpoint blockade, which either directly or indirectly promote the activation of CD8 T cells to eradicate cancer. Here, we highlight the distinct signaling mechanisms, timing and location of inhibition used by the CTLA-4 and PD-1 inhibitory receptors compared to a novel inhibitory signaling axis comprised of the bioactive lipid, lysophosphatidic acid (LPA), signaling via the LPA5 receptor expressed by CD8 T cells. Importantly, abundant evidence indicates that an LPA-LPA5 signaling axis is also exploited by diverse cancers to suppress T cell activation and function. Clearly, a thorough molecular and biochemical understanding of how diverse T cell inhibitory receptors signal to suppress T cell antigen receptor signaling and function will be important to inform the choice of which complimentary checkpoint blockade modalities might be used for a given cancer.

Lysophosphatidic acid promotes survival of T lymphoma cells by altering apoptosis and glucose metabolism

Lysophosphatidic acid (LPA) is a bioactive lipid, which plays an indispensable role in various physiological and pathological processes. Moreover, an elevated level of LPA has been observed in malignancies of different origins and implicated in their progression via modulation of proliferation, apoptosis, invasion and metastasis. Interestingly, few recent reports suggest a pivotal role of LPA-modulated metabolism in oncogenesis of ovarian cancer. However, little is understood regarding the role of LPA in the development and progression of T cell malignancies, which are considered as one of the most challenging neoplasms for clinical management. Additionally, mechanisms underlying the LPA-dependent modulation of glucose metabolism in T cell lymphoma are also not known. Therefore, the present study was undertaken to explore the role of LPA-altered apoptosis and glucose metabolism on the survival of T lymphoma cells. Observations of this investigation suggest that LPA supports survival of T lymphoma cells via altering apoptosis and glucose metabolism through changing the level of reactive species, namely nitric oxide and reactive oxygen species along with expression of various survival and glucose metabolism regulatory molecules, including hypoxia-inducible factor 1-alpha, p53, Bcl2, and glucose transporter 3, hexokinase II, pyruvate kinase muscle isozyme 2, monocarboxylate transporter 1, pyruvate dehydrogenase kinase 1. Taken together' the results of the present investigation decipher the novel mechanisms of LPA-mediated survival of T lymphoma cells via modulation of apoptosis and glucose metabolism.

Lysophosphatidic Acid Upregulates Recepteur D'origine Nantais Expression and Cell Invasion via Egr-1, AP-1, and NF-κB Signaling in Bladder Carcinoma Cells

Muscle invasive bladder carcinoma is a highly malignant cancer with a high mortality rate, due to its tendency to metastasize. The tyrosine kinase recepteur d’origine nantais (RON) promotes bladder carcinoma metastasis. Lysophosphatidic acid (LPA) is a phospholipid derivative, which acts as a signaling molecule to activate three high affinity G-protein coupled receptors, LPA1, LPA2, and LPA3. This in turn leads to cell proliferation and contributes to oncogenesis. However, little is known about the effects of LPA on invasive bladder cancer (IBC). In this study, we discovered that LPA upregulated RON expression, which in turn promoted cell invasion in bladder cancer T24 cells. As expected, we found that the LPA receptor was essential for the LPA induced increase in RON expression. More interestingly, we discovered that LPA induced RON expression via the MAPK (ERK1/2, JNK1/2), Egr-1, AP-1, and NF-κB signaling axes. These results provide experimental evidence and novel insights regarding bladder malignancy metastasis, which could be helpful for developing new therapeutic strategies for IBC treatment.

Effect of STC2 gene silencing on colorectal cancer cells

Stanniocalcin 2 (STC2), a secretory glycoprotein hormone, regulates many biological processes including cell proliferation, apoptosis, tumorigenesis and atherosclerosis. However, the effect of STC2 on proliferation, migration and epithelial-mesenchymal transition (EMT) progression in human colorectal cancer (CRC) cells remains poorly understood. The expression level of STC2 was determined by quantitative real-time polymerase chain reaction (qPCR) and western blot analysis. Cell Counting Kit-8 (CCK-8) was used to detect the viability of SW480 cells. The invasion and migration of cells were identified by wound healing and Transwell assays. The mRNA and protein expression levels of β-catenin, matrix metalloproteinase (MMP)-2, MMP-9, E-cadherin and vimentin were assessed by qPCR and western blot analysis. In the present study, it was demonstrated that STC2 was highly expressed in the CRC cell lines. After silencing of STC2, the cell viability, migration and invasion were significantly reduced. Silencing of STC2 in the CRC Sw480 cells increased the expression of E-cadherin and decreased the expression of vimentin, MMP-2 and MMP-9, compared to those in the normal and empty vector group. Furthermore, the expression of β-catenin in the STC2 gene silenced group was suppressed, and the expression of β-catenin was reversed by Wnt activator, SB216763. These results demonstrated that STC2 participates in the development and progression of CRC by promoting CRC cell proliferation, survival and migration and activating the Wnt/β-catenin signaling pathway.

Rho-Associated Protein Kinase (ROCK) Promotes Proliferation and Migration of PC-3 and DU145 Prostate Cancer Cells by Targeting LIM Kinase 1 (LIMK1) and Matrix Metalloproteinase-2 (MMP-2)

Background

In the pathogenesis and progression of prostate cancer, cell proliferation and cell migration results in tumor invasion and metastasis that is associated with patient morbidity and mortality. Rho-associated protein kinase (ROCK) has previously been shown to be upregulated in prostate cancer, but its biological role remains poorly understood. This study aimed to investigate the role of ROCK in the proliferation and migration of PC-3 and DU145 prostate cancer cells and to identify the possible targets involved by knockdown of ROCK1 and ROCK2 RNA expression.

Material/Methods

An RNA interference (RNAi) assay was performed to silence the expression of ROCK1 and ROCK2 in the PC-3 and DU145 human prostate cancer cell lines. Cells were also treated with a specific ROCK inhibitor, Y27632. A cell counting kit-8 (CCK-8) assay was used to determine the proliferation rate of prostate cancer cells, and cell migration and invasion assays were performed. Western blot and polymerase chain reaction were used to measure protein and RNA expression levels.

Results

In PC-3 and DU145 prostate cancer cells, knockdown of ROCK1 and ROCK2 reduced cell migration and invasion. ROCK1 and ROCK2 regulated cell proliferation in PC-3 and DU145 prostate cancer cells. Protein levels of phosphorylated LIM kinase 1 (p-LIMK1) and matrix metalloproteinase-2 (MMP-2) were reduced in ROCK1 and ROCK2 siRNA transfected cells.

Conclusions

In PC-3 and DU145 human prostate cancer cells, ROCK promoted cell proliferation and migration by targeting LIMK1 and MMP-2.

The role of lysophosphatidic acid in the physiology and pathology of the skin

Lysophosphatidic acid (LPA) is the simplest phospholipid found in nature. LPA is mainly biosynthesized in tissues and cells by autotoxin and PA-PLA1α/PA-PLA1β and is degraded by lipid phosphate phosphatases (LPPs). It is an important component of biofilm, an extracellular signal transmitter and intracellular second messenger. After targeting to endothelial differentiation gene (Edg) family LPA receptors (LPA1, LPA2, LPA3) and non-Edg family LPA receptors (LPA4, LPA5, LPA6), LPA mediates physiological and pathological processes such as embryonic development, angiogenesis, tumor progression, fibrogenesis, wound healing, ischemia/reperfusion injury, and inflammatory reactions. These processes are induced through signaling pathways including mitogen-activated protein kinase (MAPK), phosphatidylinositol-3-kinase (PI3K)/Akt, protein kinase C (PKC)-GSK3β-β-catenin, Rho, Stat, and hypoxia-inducible factor 1-alpha (HIF-1α). LPA is involved in multiple physiological and pathological processes in the skin. It not only regulates skin function but also plays an important role in hair follicle development, skin wound healing, pruritus, skin tumors, and scleroderma. Pharmacological inhibition of LPA synthesis or antagonization of LPA receptors is a new strategy for the treatment of various skin disorders. This review focuses on the current understanding of the pathophysiologic role of LPA in the skin.

Development and biological evaluation of fluorophosphonate-modified hydroxyapatite for orthopaedic applications

There is an incentive to functionalise hydroxyapatite (HA) for orthopaedic implant use with bioactive agents to encourage superior integration of the implants into host bone. One such agent is (3S) 1-fluoro-3-hydroxy-4-(oleoyloxy) butyl-1-phosphonate (FHBP), a phosphatase-resistant lysophosphatidic acid (LPA) analogue. We investigated the effect of an FHBP-HA coating on the maturation of human (MG63) osteoblast-like cells. Optimal coating conditions were identified and cell maturation on modified and unmodified, control HA surfaces was assessed. Stress tests were performed to evaluate coating survivorship after exposure to mechanical and thermal insults that are routinely encountered in the clinical environment. MG63 maturation was found to be three times greater on FHBP-modified HA compared to controls (p < 0.0001). There was no significant loss of coating bioactivity after autoclaving (P = 0.9813) although functionality declined by 67% after mechanical cleaning and reuse (p < 0.0001). The bioactivity of modified disks was significantly greater than that of controls following storage for up to six months (p < 0.001). Herein we demonstrate that HA can be functionalised with FHBP in a facile, scalable manner and that this novel surface has the capacity to enhance osteoblast maturation. Improving the biological performance of HA in a bone regenerative setting could be realised through the simple conjugation of bioactive LPA species in the future. Depicted is a stylised summary of hydroxyapatite (HA) surface modification using an analogue of lysophosphatidic acid, FHBP. a HA surfaces are simply steeped in an aqueous solution of 2 μM FHBP. b The polar head group of some FHBP molecules react with available hydroxyl residues at the mineral surfaces forming robust HA-O-P bonds leaving acyl chain extensions perpendicular to the HA surface. These fatty acyl chains provide points of integration for other FHBP molecules to facilitate their self-assembly. This final surface finish enhanced the human osteoblast maturation response to calcitriol, the active vitamin D3 metabolite.

Opposite Interplay Between the Canonical WNT/β-Catenin Pathway and PPAR Gamma: A Potential Therapeutic Target in Gliomas

In gliomas, the canonical Wingless/Int (WNT)/β-catenin pathway is increased while peroxisome proliferator-activated receptor gamma (PPAR-γ) is downregulated. The two systems act in an opposite manner. This review focuses on the interplay between WNT/β-catenin signaling and PPAR-γ and their metabolic implications as potential therapeutic target in gliomas. Activation of the WNT/β-catenin pathway stimulates the transcription of genes involved in proliferation, invasion, nucleotide synthesis, tumor growth, and angiogenesis. Activation of PPAR-γ agonists inhibits various signaling pathways such as the JAK/STAT, WNT/β-catenin, and PI3K/Akt pathways, which reduces tumor growth, cell proliferation, cell invasiveness, and angiogenesis. Nonsteroidal anti-inflammatory drugs, curcumin, antipsychotic drugs, adiponectin, and sulforaphane downregulate the WNT/β-catenin pathway through the upregulation of PPAR-γ and thus appear to provide an interesting therapeutic approach for gliomas. Temozolomide (TMZ) is an antiangiogenic agent. The downstream action of this opposite interplay may explain the TMZ-resistance often reported in gliomas.

Lysophosphatidic acid enhances neointimal hyperplasia following vascular injury through modulating proliferation, autophagy, inflammation and oxidative stress

Lysophosphatidic acid (LPA), which is one of the intermediate products of membrane phospholipid metabolism, is a bioactive phospholipid that possesses diverse activities. In the present study, the effects of LPA on neointimal formation following vascular injury were investigated. A carotid artery balloon injury model was employed in the present study, and following vascular injury, rats received an intraperitoneal injection of 1 mg/kg LPA. Subsequently, histopathological alterations were assessed by hematoxylin and eosin staining, the expression levels of proliferating cell nuclear antigen (PCNA) were detected by immunohistochemistry, apoptosis was assessed via a terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling assay, and the expression levels of apoptosis-associated and autophagy-associated proteins were detected by western blotting. In addition, inflammatory and oxidative stress-associated factors were assessed by reverse transcription-quantitative polymerase chain reaction or corresponding kits. The results of the present study demonstrated that LPA enhanced vascular injury-induced neointimal hyperplasia. LPA further elevated the expression levels of PCNA in the injured carotid artery tissues. LPA exhibited no effect on apoptosis in carotid artery tissues, whereas it modulated autophagy in the injured carotid artery tissues. Furthermore, LPA enhanced vascular injury-induced inflammation and oxidative stress. The present study demonstrated that LPA may enhance neointimal hyperplasia following vascular injury by modulating proliferation, autophagy, inflammation and oxidative stress, but not apoptosis. Furthermore LPA may contribute to the pathology of atherosclerosis and may be considered a promising therapeutic target for the treatment of atherosclerosis.

Targeting few to help hundreds: JAK, MAPK and ROCK pathways as druggable targets in atypical chronic myeloid leukemia

Atypical Chronic Myeloid Leukemia (aCML) is a myeloproliferative neoplasm characterized by neutrophilic leukocytosis and dysgranulopoiesis. From a genetic point of view, aCML shows a heterogeneous mutational landscape with mutations affecting signal transduction proteins but also broad genetic modifiers and chromatin remodelers, making difficult to understand the molecular mechanisms causing the onset of the disease. The JAK-STAT, MAPK and ROCK pathways are known to be responsible for myeloproliferation in physiological conditions and to be aberrantly activated in myeloproliferative diseases. Furthermore, experimental evidences suggest the efficacy of inhibitors targeting these pathways in repressing myeloproliferation, opening the way to deep clinical investigations. However, the activation status of these pathways is rarely analyzed when genetic mutations do not occur in a component of the signaling cascade. Given that mutations in functionally unrelated genes give rise to the same pathology, it is tempting to speculate that alteration in the few signaling pathways mentioned above might be a common feature of pathological myeloproliferation. If so, targeted therapy would be an option to be considered for aCML patients.

Aberrant lipid metabolism in cancer cells - the role of oncolipid-activated signaling

Metabolic activity of malignant cells is very different from that of their nontransformed equivalents, which establishes metabolic reprogramming as an important hallmark of every transformed cell. In particular, the current arena of research in this field aims to understand the regulatory effect of oncogenic signaling on metabolic rewiring in transformed cells in order to exploit this for therapeutic benefit. Alterations in lipid metabolism are one of the main aspects of metabolic rewiring of transformed cells. Up-regulation of several lipogenic enzymes has been reported to be a characteristic of various cancer types. Lysophosphatidic acid (LPA), a simple byproduct of the lipid biosynthesis pathway, has gained immense importance due to its elevated level in several cancers and associated growth-promoting activity. Importantly, a current study revealed its role in increased de novo lipid synthesis through up-regulation of sterol regulatory element-binding protein 1, a master regulator of lipid metabolism. This review summarizes the recent insights in the field of oncolipid LPA-mediated signaling in regard to lipid metabolism in cancers. Future work in this domain is required to understand the up-regulation of the de novo synthesis pathway and the role of its end products in malignant cells. This will open a new arena of research toward the development of specific metabolic inhibitors that can add to the pre-existing chemotherapeutics in order to increase the efficacy of clinical output in cancer patients.

Gene regulatory networking reveals the molecular cue to lysophosphatidic acid-induced metabolic adaptations in ovarian cancer cells

Extravasation and metastatic progression are two main reasons for the high mortality rate associated with cancer. The metastatic potential of cancer cells depends on a plethora of metabolic challenges prevailing within the tumor microenvironment. To achieve higher rates of proliferation, cancer cells reprogram their metabolism, increasing glycolysis and biosynthetic activities. Just why this metabolic reprogramming predisposes cells towards increased oncogenesis remains elusive. The accumulation of myriad oncolipids in the tumor microenvironment has been shown to promote the invasiveness of cancer cells, with lysophosphatidic acid (LPA) being one such critical factor enriched in ovarian cancer patients. Cellular bioenergetic studies confirm that oxidative phosphorylation is suppressed and glycolysis is increased with long exposure to LPA in ovarian cancer cells compared with non‐transformed epithelial cells. We sought to uncover the regulatory complexity underlying this oncolipid‐induced metabolic perturbation. Gene regulatory networking using RNA‐Seq analysis identified the oncogene ETS‐1 as a critical mediator of LPA‐induced metabolic alterations for the maintenance of invasive phenotype. Moreover, LPA receptor‐2 specific PtdIns3K‐AKT signaling induces ETS‐1 and its target matrix metalloproteases. Abrogation of ETS‐1 restores cellular bioenergetics towards increased oxidative phosphorylation and reduced glycolysis, and this effect was reversed by the presence of LPA. Furthermore, the bioenergetic status of LPA‐treated ovarian cancer cells mimics hypoxia through induction of hypoxia‐inducible factor‐1α, which was found to transactivate ets‐1. Studies in primary tumors generated in syngeneic mice corroborated the in vitro findings. Thus, our study highlights the phenotypic changes induced by the pro‐metastatic factor ETS‐1 in ovarian cancer cells. The relationship between enhanced invasiveness and metabolic plasticity further illustrates the critical role of metabolic adaptation of cancer cells as a driver of tumor progression. These findings reveal oncolipid‐induced metabolic predisposition as a new mechanism of tumorigenesis and propose metabolic inhibitors as a potential approach for future management of aggressive ovarian cancer.

Lysophosphatidic Acid Promotes Epithelial to Mesenchymal Transition in Ovarian Cancer Cells by Repressing SIRT1

BACKGROUND/AIMS

Epithelial-to-mesenchymal transition (EMT) plays an essential role in the transition from early to invasive phenotype, however the underlying mechanisms still remain elusive. Herein, we propose a mechanism through which the class-III deacetylase SIRT1 regulates EMT in ovarian cancer (OC) cells.

METHODS

Expression analysis was performed using Q-PCR, western blot, immunofluorescence and fluorescence-IHC study. Matrigel invasion assay was used for the invasion study. Morphological alterations were observed by phalloidin-staining. Co-immunoprecipitation study was performed to analyze protein-protein interaction.

RESULTS

Overexpression of SIRT1-WT as well as Resveratrol-mediated SIRT1 activation antagonized the invasion of OC cells by suppressing EMT. SIRT1 deacetylates HIF1α, to inactivate its transcriptional activity. To further validate HIF1α inactivation, its target gene, i.e. ZEB1, an EMT-inducing factor was found to attenuate upon SIRT1 activation. To uncover the regulatory factor governing SIRT1 expression, lysophosphatidic acid (LPA), a highly enriched oncolipid in ascites/serum of OC patients, was found to down-regulate SIRT1 expression. Importantly, LPA was found to induce the mesenchymal switch in OC cells through suppression of SIRT1. Decreased level of SIRT1 was further validated in ovarian tissue samples of OC patients.

CONCLUSION

We have identified a mechanism that relates SIRT1 down-regulation to LPA-induced EMT in OC cells and may open new arenas on developing novel anti-cancer therapeutics.

Role of Wasp and the small GTPases RhoA, RhoB, and Cdc42 during capacitation and acrosome reaction in spermatozoa of English guinea pigs

Cytoskeleton remodeling is necessary for capacitation and the acrosome reaction in spermatozoa. F-actin is located in the acrosome and equatorial region during capacitation, but is relocated in the post-acrosomal region during the acrosome reaction in spermatozoa from bull, rat, mice, and guinea pig. Actin polymerization and relocalization are generally regulated by small GTPases that activate Wasp protein, which coordinates with Arp2/3, profilin I, and profilin II to complete cytoskeletal remodeling. This sequence of events is not completely described in spermatozoa, though. Therefore, the aim of this study was to determine if Wasp interacts with small GTPases (RhoA, RhoB, and Cdc42) and proteins (Arp2/3, profilin I, and profilin II) that co-localize with F-actin during capacitation and the acrosome reaction in English guinea pig spermatozoa obtained from the vas deferens. The spermatozoa were capacitated in calcium-free medium, incubated with an activator or an inhibitor of GTPases, and then induced to acrosome react using calcium. The distribution patterns of F-actin were compared to the patterns of Wasp and its putative interaction partners: Wasp and RhoB, but not RhoA or Cdc42, localization overlap with F-actin during capacitation and the acrosome reaction. Activation of small GTPases localized RhoB to the post-acrosomal region whereas their inhibition prevented acrosome exocytosis. Arp2/3 and profilin II appear to interact with Wasp in the post-acrosomal region and flagellum, while profilin I and Wasp could be found in the equatorial region. Thus, Wasp and F-actin distribution overlap during capacitation and acrosome reaction, and small GTPases play an important role in cytoskeleton remodeling during these processes in spermatozoa. Mol. Reprod. Dev. 83: 927-937, 2016 © 2016 Wiley Periodicals, Inc.

Pulmonary Toxicities of Gefitinib in Patients With Advanced Non-Small-Cell Lung Cancer: A Meta-Analysis of Randomized Controlled Trials

Gefitinib is a selective tyrosine kinase inhibitor of the epidermal growth factor receptor (EGFR) used to treat adults with EGFR mutation-positive non-small-cell lung cancer (NSCLC). Clinical benefits of gefitinib administration in NSCLC patients have been observed in clinical practice, but the extent of the pulmonary toxicity of gefitinib in patients with advanced NSCLC remains unclear. The aim of this systematic review was to evaluate the overall incidence and risk of gefitinib-related pulmonary toxicity in advanced NSCLC patients. Relevant trials were identified from the databases of Pubmed, Embase, Cochrane Library, and the clinicaltrials.gov of the U.S. National Institutes of Health. The outcomes included the overall incidence, odds ratios (ORs), and 95% confidence intervals (CIs). Fixed-effects models were used in the statistical analyses according to the heterogeneity of the included studies. According to the data from the included trials, the overall incidence of high-grade hemoptysis, pneumonia, pneumonitis, and interstitial lung disease (ILD) was 0.49% (95% CI: 0.24%-0.99%), 2.33% (95% CI: 1.47%-3.66%), 2.24% (95% CI: 1.34%-3.72%), and 1.43% (95% CI: 0.98%-2.09%), respectively. The pooled ORs of high-grade hemoptysis, pneumonia, pneumonitis, and ILD were 1.73 (95% CI: 0.46-6.52; P = 0.42), 0.99 (95% CI: 0.66-1.49; P = 0.95), 4.70 (95% CI: 1.48-14.95; P = 0.0087), and 2.64 (95% CI: 1.22-5.69; P = 0.01), respectively. Gefitinib was associated with a significantly increased risk of high-grade/fatal ILD and pneumonitis compared with the controls, whereas the risk of other high-grade pulmonary events (pneumonia and hemoptysis) was not significant. Careful surveillance of gefitinib-related pulmonary toxicity is critical for the safe use of this drug.