LPA receptor 1 mediates LPA-induced ovarian cancer metastasis: an in vitro and in vivo study

Friend and foe: the regulation network of ascites components in ovarian cancer progression

The tumor microenvironment (TME) and its complex role in cancer progression have been hotspots of cancer research in recent years. Ascites, which occurs frequently in patients with ovarian cancer especially in advanced stages, represents a unique TME. Malignant ascites contains abundant cellular and acellular components that play important roles in tumorigenesis, growth, metastasis, and chemoresistance of ovarian cancer through complex molecular mechanisms and signaling pathways. As a valuable liquid biopsy sample, ascites fluid is also of great significance for the prognostic analysis of ovarian cancer. The components of ovarian cancer ascites are generally considered to comprise tumor-promoting factors; however, in recent years studies have found that ascites also contains tumor-suppressing factors, raising new perspectives on interactions between ascites and tumors. Malignant ascites directly constitutes the ovarian cancer microenvironment, therefore, the study of its components will aid in the development of new therapeutic strategies. This article reviews the current research on tumor-promoting and tumor-suppressing factors and molecular mechanisms of their actions in ovarian cancer-derived ascites and therapeutic strategies targeting ascites, which may provide references for the development of novel therapeutic targets for ovarian cancer in the future.

LPAR1 and aberrantly expressed LPAR3 differentially promote the migration and proliferation of malignant peripheral nerve sheath tumor cells

Schwann cell-derived neoplasms known as malignant peripheral nerve sheath tumors (MPNSTs) are the most common malignancy and the leading cause of death in individuals with neurofibromatosis Type 1. Using genome-scale shRNA screens, we have previously found evidence suggesting that lysophosphatidic acid receptors (LPARs) are essential for MPNST proliferation and/or survival. Here, we examine the expression and mutational status of all six LPA receptors in MPNSTs, assess the role that individual LPA receptors play in MPNST physiology and examine their ability to activate key neurofibromin-regulated signaling cascades. We found that human Schwann cells express LPAR1 and LPAR6, while MPNST cells express predominantly LPAR1 and LPAR3. Whole exome sequencing of 16 MPNST cell lines showed no evidence of mutations in any LPAR genes or ENPP2, a gene encoding a major LPA biosynthetic enzyme. Oleoyl-LPA, an LPA variant with an unsaturated side chain, promoted MPNST cell proliferation and migration. LPAR1 knockdown ablated the promigratory effect of LPA, while LPAR3 knockdown decreased proliferation. Inhibition of R-Ras signaling with a doxycycline-inducible dominant negative (DN) R-Ras mutant, which inhibits both R-Ras and R-Ras2, blocked LPA's promigratory effect. In contrast, DN R-Ras did not affect migration induced by neuregulin-1β (NRG1β), suggesting that LPA and NRG1β promote MPNST migration via distinct pathways. LPA-induced migration was also inhibited by Y27632, an inhibitor of the ROCK1/2 kinases that mediate R-Ras effects in MPNSTs. Thus, LPAR1 and aberrantly expressed LPAR3 mediate distinct effects in MPNSTs. These receptors and the signaling pathways that they regulate are potentially useful therapeutic targets in MPNSTs.

The lysophosphatidic acid-regulated signal transduction network in ovarian cancer cells and its role in actomyosin dynamics, cell migration and entosis

Lysophosphatidic acid (LPA) species accumulate in the ascites of ovarian high-grade serous cancer (HGSC) and are associated with short relapse-free survival. LPA is known to support metastatic spread of cancer cells by activating a multitude of signaling pathways via G-protein-coupled receptors of the LPAR family. Systematic unbiased analyses of the LPA-regulated signal transduction network in ovarian cancer cells have, however, not been reported to date. Methods: LPA-induced signaling pathways were identified by phosphoproteomics of both patient-derived and OVCAR8 cells, RNA sequencing, measurements of intracellular Ca²⁺ and cAMP as well as cell imaging. The function of LPARs and downstream signaling components in migration and entosis were analyzed by selective pharmacological inhibitors and RNA interference. Results: Phosphoproteomic analyses identified > 1100 LPA-regulated sites in > 800 proteins and revealed interconnected LPAR1, ROCK/RAC, PKC/D and ERK pathways to play a prominent role within a comprehensive signaling network. These pathways regulate essential processes, including transcriptional responses, actomyosin dynamics, cell migration and entosis. A critical component of this signaling network is MYPT1, a stimulatory subunit of protein phosphatase 1 (PP1), which in turn is a negative regulator of myosin light chain 2 (MLC2). LPA induces phosphorylation of MYPT1 through ROCK (T853) and PKC/ERK (S507), which is majorly driven by LPAR1. Inhibition of MYPT1, PKC or ERK impedes both LPA-induced cell migration and entosis, while interference with ROCK activity and MLC2 phosphorylation selectively blocks entosis, suggesting that MYPT1 figures in both ROCK/MLC2-dependent and -independent pathways. We finally show a novel pathway governed by LPAR2 and the RAC-GEF DOCK7 to be indispensable for the induction of entosis. Conclusion: We have identified a comprehensive LPA-induced signal transduction network controlling LPA-triggered cytoskeletal changes, cell migration and entosis in HGSC cells. Due to its pivotal role in this network, MYPT1 may represent a promising target for interfering with specific functions of PP1 essential for HGSC progression.

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.

Gα12 and Gα13: Versatility in Physiology and Pathology

G protein-coupled receptors (GPCRs), as the largest family of receptors in the human body, are involved in the pathological mechanisms of many diseases. Heterotrimeric G proteins represent the main molecular switch and receive cell surface signals from activated GPCRs. Growing evidence suggests that Gα₁₂ subfamily (Gα_12/13)-mediated signaling plays a crucial role in cellular function and various pathological processes. The current research on the physiological and pathological function of Gα_12/13 is constantly expanding, Changes in the expression levels of Gα_12/13 have been found in a wide range of human diseases. However, the mechanistic research on Gα_12/13 is scattered. This review briefly describes the structural sequences of the Gα_12/13 isoforms and introduces the coupling of GPCRs and non-GPCRs to Gα_12/13. The effects of Gα_12/13 on RhoA and other signaling pathways and their roles in cell proliferation, migration, and immune cell function, are discussed. Finally, we focus on the pathological impacts of Gα_12/13 in cancer, inflammation, metabolic diseases, fibrotic diseases, and circulatory disorders are brought to focus.

Identification of key genes associated with polycystic ovary syndrome (PCOS) and ovarian cancer using an integrated bioinformatics analysis

BACKGROUND

Accumulating evidence suggests a strong association between polycystic ovary syndrome (PCOS) and ovarian cancer (OC), but the potential molecular mechanism remains unclear. In this study, we identified previously unrecognized genes that are significantly correlated with PCOS and OC via bioinformatics.

MATERIALS AND METHODS

Multiple bioinformatic analyses, such as differential expression analysis, univariate Cox analysis, functional and pathway enrichment analysis, protein-protein interaction (PPI) network construction, survival analysis, and immune infiltration analysis, were utilized. We further evaluated the effect of OGN on FSHR expression via immunofluorescence.

RESULTS

TCGA-OC, GSE140082 (for OC) and GSE34526 (for PCOS) datasets were downloaded. Twelve genes, including RNF144B, LPAR3, CRISPLD2, JCHAIN, OR7E14P, IL27RA, PTPRD, STAT1, NR4A1, OGN, GALNT6 and CXCL11, were identified as signature genes. Drug sensitivity analysis showed that OGN might represent a hub gene in the progression of PCOS and OC. Experimental analysis found that OGN could increase FSHR expression, indicating that OGN could regulate the hormonal response in PCOS and OC. Furthermore, correlation analysis indicated that OGN function might be closely related to m6A and ferroptosis.

CONCLUSIONS

Our study identified a 12-gene signature that might be involved in the prognostic significance of OC. Furthermore, the hub gene OGN represent a significant gene involved in OC and PCOS progression by regulating the hormonal response.

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.

G Protein-Coupled receptors and heterotrimeric G proteins as cancer drivers

G protein-coupled receptors (GPCRs) and heterotrimeric G proteins play central roles in a diverse array of cellular processes. As such, dysregulation of GPCRs and their coupled heterotrimeric G proteins can dramatically alter the signalling landscape and functional state of a cell. Consistent with their fundamental physiological functions, GPCRs and their effector heterotrimeric G proteins are implicated in some of the most prevalent human diseases, including a complex disease such as cancer that causes significant morbidity and mortality worldwide. GPCR/G protein-mediated signalling impacts oncogenesis at multiple levels by regulating tumour angiogenesis, immune evasion, metastasis, and drug resistance. Here, we summarize the growing body of research on GPCRs and their effector heterotrimeric G proteins as drivers of cancer initiation and progression, and as emerging antitumoural therapeutic targets.

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.

Emerging Roles for Ion Channels in Ovarian Cancer: Pathomechanisms and Pharmacological Treatment

Ovarian cancer (OC) is the deadliest gynecologic cancer, due to late diagnosis, development of platinum resistance, and inadequate alternative therapy. It has been demonstrated that membrane ion channels play important roles in cancer processes, including cell proliferation, apoptosis, motility, and invasion. Here, we review the contribution of ion channels in the development and progression of OC, evaluating their potential in clinical management. Increased expression of voltage-gated and epithelial sodium channels has been detected in OC cells and tissues and shown to be involved in cancer proliferation and invasion. Potassium and calcium channels have been found to play a critical role in the control of cell cycle and in the resistance to apoptosis, promoting tumor growth and recurrence. Overexpression of chloride and transient receptor potential channels was found both in vitro and in vivo, supporting their contribution to OC. Furthermore, ion channels have been shown to influence the sensitivity of OC cells to neoplastic drugs, suggesting a critical role in chemotherapy resistance. The study of ion channels expression and function in OC can improve our understanding of pathophysiology and pave the way for identifying ion channels as potential targets for tumor diagnosis and treatment.

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.

The transcriptome-wide association search for genes and genetic variants which associate with BMI and gestational weight gain in women with type 1 diabetes

BACKGROUND

Clinical data suggest that BMI and gestational weight gain (GWG) are strongly interconnected phenotypes; however, the genetic basis of the latter is rather unclear. Here we aim to find genes and genetic variants which influence BMI and/or GWG.

METHODS

We have genotyped 316 type 1 diabetics using Illumina Infinium Omni Express Exome-8 v1.4 arrays. The GIANT, ARIC and T2D-GENES summary statistics were used for TWAS (performed with PrediXcan) in adipose tissue. Next, the analysis of association of imputed expression with BMI in the general and diabetic cohorts (Analysis 1 and 2) or GWG (Analysis 3 and 4) was performed, followed by variant association analysis (1 Mb around identified loci) with the mentioned phenotypes.

RESULTS

In Analysis 1 we have found 175 BMI associated genes and 19 variants (p < 10-4) which influenced GWG, with the strongest association for rs11465293 in CCL24 (p = 3.18E-06). Analysis 2, with diabetes included in the model, led to discovery of 1812 BMI associated loci and 207 variants (p < 10-4) influencing GWG, with the strongest association for rs9690213 in PODXL (p = 9.86E-07). In Analysis 3, among 648 GWG associated loci, 2091 variants were associated with BMI (FDR < 0.05). In Analysis 4, 7 variants in GWG associated loci influenced BMI in the ARIC cohort.

CONCLUSIONS

Here, we have shown that loci influencing BMI might have an impact on GWG and GWG associated loci might influence BMI, both in the general and T1DM cohorts. The results suggest that both phenotypes are related to insulin signaling, glucose homeostasis, mitochondrial metabolism, ubiquitinoylation and inflammatory responses.

Identified the novel resistant biomarkers for taxane-based therapy for triple-negative breast cancer

Developing treatment strategies for triple-negative breast cancer (TNBC) has become an important clinical challenge. Currently, taxane-based chemotherapy is one of the standard treatments for TNBC. However, determining the key factor of taxane-resistance is urgently in need for clinical treatment for breast cancer. We used GEO data to generate paclitaxel resistance in two basal-like TNBC cell lines (SUM149 and MDA-MB-468). Seventy-one common upregulated differentially expressed genes (DEGs) and 11 downregulated DEGs were found to be related to paclitaxel resistance. By constructing protein-protein interactions, 28 hub proteins with a degree cutoff criterion of ≥1 were found. Nine hub genes (COL4A6, COL4A5, IL6, PDGFA, LPAR1, FYB, IL20, IL18R1 and INHBA) are involved in important signaling pathways. We found that upregulated PDGFA and downregulated COL4A6 were significantly associated with an insensitive response to neoadjuvant paclitaxel-based therapy. A Kaplan-Meier plot was created to check the prognostic values of 11 hub DEGs in terms of recurrence-free survival. High expressions of PDGFA and LAMB3 were correlated with poor recurrence-free survival, while low levels of FYB, IL18R1, and RASGRP1 indicated poorer relapse-free survival. Our results suggest that PDGFA, COL4A6, LPAR1, FYB, COL4A5, and RASGRP1 might be candidate target genes for taxane-based therapy in basal-like TNBC.

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.

EZH2 promotes the expression of LPA1 by mediating microRNA-139 promoter methylation to accelerate the development of ovarian cancer

Background

It has been known that ovarian cancer (OC) is a leading cause for women mortality globally. We aimed to analyze the underlying mechanism supporting that enhancer of zeste homolog 2 (EZH2) affected the development of OC via the involvement of microRNA-139 (miR-139)/transforming growth factor beta (TGF-β)/lysophosphatidic acid-1 (LPA1) axis.

Methods

High expression patterns of EZH2 and miR-139 and low LPA1 expression pattern in OC were evaluated using RT-qPCR and immunoblotting, while their correlation was assessed by the Spearman’s rank and Pearson’s correlation coefficient. Subsequently, dual-luciferase reporter gene assay was applied to validate the binding relationship between miR-139 and LPA1, while H3K27me enrichment was assessed by ChIP assay. After that, the effects of altered expression of EZH2, miR-194, or LPA1 on the cell biological functions and the expression pattern of TGF-related factors were evaluated.

Results

We found that EZH2 repressed the miR-139 expression pattern by recruiting H3K27me3 to promote miR-139 promoter methylation, while silencing of EZH2 suppressed in vitro cancer progression by increasing miR-139. LPA1 was a target of miR-139, and could activate the TGF-β signaling pathway, which hastened the OC progression. miR-139-targeted inhibition of LPA1 and LPA1-activated TGF-β signaling pathway were evidenced to be critical mechanisms underlying the effects of EZH2 on OC cells. Lastly, silencing of EZH2 inhibited the xenograft growth in vivo.

Conclusions

EZH2 could down-regulate miR-139 expression pattern by recruiting H3K27me3 to promote the miR-139 promoter methylation and activate the TGF-β pathway by up-regulating LPA1, which contributed to the progression of OC. The current study may possess potentials for OC treatment.

Overexpression of microRNA-367 inhibits angiogenesis in ovarian cancer by downregulating the expression of LPA1

Background

Compelling evidences reported the role of microRNAs (miRNAs) in ovarian cancer. However, little was known regarding the molecular mechanism of miR-367 in ovarian cancer. This study intended to investigate the role and regulatory mechanism of miR-367 in ovarian cancer involving lysophosphatidic acid receptor-1 (LPA1).

Methods

Potentially regulatory miRNAs in ovarian cancer were obtained from bioinformatics analysis. RT-qPCR was used to detect miR-367 expression in both ovarian cancer tissues and relevant adjacent normal tissues. Relationship between miR-367 and LPA1 was predicted by miRNA database and further verified using dual luciferase reporter gene assay and RIP. EdU and Transwell assay were used to measure the proliferation and invasion ability of cells. Moreover, tube formation and chick chorioallantois membrane (CAM) assay were performed to determine angiogenesis of human umbilical vein endothelial cells (HUVECs). Finally, the roles of LPA1 in tumor growth was also studied using nude mice xenograft assay.

Results

High expression of LPA1 and low expression of miR-367 were observed in ovarian cancer tissues and cells. Overexpressed miR-367 downregulated LPA1 expression to inhibit proliferation, invasion, and angiogenesis of cancer cells. Low expression of LPA1 suppressed tumor formation and repressed angiogenesis in ovarian in vivo.

Conclusion

All in all, overexpression of miR-367 downregulated LPA1 expression to inhibit ovarian cancer progression, which provided a target for the cancer treatment.

Sorting Nexin 27 as a potential target in G protein‑coupled receptor recycling for cancer therapy (Review)

G protein-coupled receptors (GPCRs) are the largest family of membrane receptors and activate several downstream signaling pathways involved in numerous physiological cellular processes. GPCRs are usually internalized and desensitized by intracellular signals. Numerous studies have shown that several GPCRs interact with sorting nexin 27 (SNX27), a cargo selector of the retromer complex, and are recycled from endosomes to the plasma membrane. Recycled GPCRs usually contain specific C-terminal postsynaptic density protein 95/Discs large protein/Zonula occludens 1 (PDZ) binding motifs, which are specifically recognized by SNX27, and return to the cell surface as functionally naïve receptors. Aberrant endosome-to-membrane recycling of GPCRs mediated by SNX27 may serve a critical role in cancer growth and development. Therefore, SNX27 may be a novel target for cancer therapies.

Dynamic actin remodeling in response to lysophosphatidic acid

Lysophosphatidic acid (LPA) is a multifunctional regulator of actin cytoskeleton that exerts a dramatic impact on the actin cytoskeleton to build a platform for diverse cellular processes including growth cone guidance, neurite retraction and cell motility. It has been implicated in the formation and dissociation of complexes between actin and actin binding proteins, supporting its role in actin remodeling. Several studies point towards its ability to facilitate formation of special cellular structures including focal adhesions and actin stress fibres by phosphoregulation of several actin associated proteins and their multiple regulatory kinases and phosphatases. In addition, multiple levels of crosstalk among the signaling cascades activated by LPA, affect actin cytoskeleton-mediated cell migration and chemotaxis which in turn play a crucial role in cancer metastasis. In the current review, we have attempted to highlight the role of LPA as an actin modulator which functions by controlling activities of specific cellular proteins that underlie mechanisms employed in cytoskeletal and pathophysiological events within the cell. Further studies on the actin affecting/remodeling activity of LPA in different cell types will no doubt throw up many surprises essential to gain a full understanding of its contribution in physiological processes as well as in diseases.Communicated by Ramaswamy H. Sarma.

Long noncoding RNA ZFAS1 promotes tumorigenesis and metastasis in nasopharyngeal carcinoma by sponging miR-892b to up-regulate LPAR1 expression

OBJECTIVE

In this study, we explored the NPC-specific expression of ZFAS1 and the mechanism of ZFAS1-mediated growth, aggressiveness and tumorigenesis in NPC.

METHODS

The expression profile of lncRNAs was detected in NPC tissues and matching para-carcinoma tissues using microarray analysis. LncRNA-miRNA and miRNA-mRNA interaction networks were constructed using the miRcode v11 and TargetScanHuman v7.2 web server and then validated using dual-luciferase assay. Western blot and RT-qPCR were performed to detect protein and RNA expression. The effects of ZFAS1, miR-892b and LPAR1 dysregulation on the proliferative, migratory and invasive abilities of NPC cells were observed using colony formation, cell counting kit-8 (CCK-8) and transwell assays in vitro. In vivo, a xenograft nude mouse model was established to detect the impact of ZFAS1 dysregulation on the tumorigenicity of NPC cells.

RESULTS

The expression of multiple lncRNAs, of which ZFAS1 was up-regulated, was dysregulated in NPC tissues. ZFAS1 directly targeted miR-892b, and miR-892b negatively regulated the expression of downstream LPAR1. The proliferation, migration and invasion of NPC cells could be largely enhanced by the downregulation of miR-892b as well as the up-regulation of ZFAS1 and LPAR1, while the overexpression of miR-892b and the downregulation of ZFAS1 and LPAR1 decreased these abilities. In nude mice, the growth of tumour xenografts formed by HONE1 cells was significantly suppressed when ZFAS1 was silenced.

CONCLUSION

The study demonstrated that lncRNA ZFAS1 may act as a promoter of tumorigenesis and metastasis in nasopharyngeal carcinoma, by up-regulating the expression of LPAR1 in a miR-892b-dependent manner.

Diverse Effects of Lysophosphatidic Acid Receptors on Ovarian Cancer Signaling Pathways

Lysophosphatidic acid (LPA) is a bioactive phospholipid with mitogenic and growth factor-like activities affecting cell invasion, cancer progression, and resistance. It is produced mainly by autotaxin and acts on six G-protein-coupled receptors, LPAR1-6. LPA has recently been implicated as a growth factor present in ascites of ovarian cancer patients. However, mitogenic pathways stimulated by LPA via its receptors may involve any novel, thus far uncharacterized, signaling pathway(s). Here we show that three LPA receptors are involved in tumor progression by activation of both the AKT and ERK signaling pathways. CRISPR-edited LPAR2 and LPAR3 knockouts have opposing effects on ERK activation, whereas LPAR6 is involved in the activation of AKT, affecting cell migration and invasion. Our study identifies specific molecular machinery triggered by LPA and its receptors that modulates tumor cells and can serve as therapeutic target in this malignancy.

Inhibitory short peptides targeting EPS8/ABI1/SOS1 tri-complex suppress invasion and metastasis of ovarian cancer cells

Background

We aimed to develop inhibitory short peptides that can prevent protein interactions of SOS1/EPS8/ABI1 tri-complex, a key component essential for ovarian cancer metastasis.

Methods

Plasmids containing various regions of HA-tagged ABI1 were co-transfected into ovarian cancer cells with Flag-tagged SOS1 or Myc-tagged EPS8. Co-immunoprecipitation and GST-pulldown assay were used to identify the regions of ABI1 responsible for SOS1 and EPS8 binding. Inhibitory short peptides of these binding regions were synthesized and modified with HIV-TAT sequence. The blocking effects of the peptides on ABI1-SOS1 or ABI1-EPS8 interactions in vitro and in vivo were determined by GST-pulldown assay. The capability of these short peptides in inhibiting invasion and metastasis of ovarian cancer cell was tested by Matrigel invasion assay and peritoneal metastatic colonization assay.

Results

The formation of endogenous SOS1/EPS8/ABI1 tri-complex was detected in the event of LPA-induced ovarian cancer cell invasion. In the tri-complex, ABI1 acted as a scaffold protein holding together SOS1 and EPS8. The SH3 and poly-proline+PxxDY regions of ABI1 were responsible for SOS1 and EPS8 binding, respectively. Inhibitory short peptides p + p-8 (ppppppppvdyedee) and SH3–3 (ekvvaiydytkdkddelsfmegaii) could block ABI1-SOS1 and ABI1-EPS8 interaction in vitro. TAT-p + p-8 peptide could disrupt ABI1-EPS8 interaction and suppress the invasion and metastasis of ovarian cancer cells in vivo.

Conclusions

TAT-p + p-8 peptide could efficiently disrupt the ABI1-EPS8 interaction, tri-complex formation, and block the invasion and metastasis of ovarian cancer cells.

LPAR1 regulates the development of intratumoral heterogeneity in ovarian serous cystadenocarcinoma by activating the PI3K/AKT signaling pathway

Background

To explore the role of lysophosphatidic acid receptor 1 (LPAR1) and its correlation with the PI3K/AKT pathway in the development of intratumoral heterogeneity (ITH) in human ovarian serous cystadenocarcinoma (OSC).

Methods

Immunohistochemical staining was performed to detect LPAR1 expression in matched primary and recurrent lesions from the same patients. Cell models of ITH were established using the limiting dilution methodology and Transwell invasion/migration assays. LPAR1 expression in the ITH cell models was silenced or upregulated with lentiviral particles, and the biological characteristics were evaluated using various in vitro and in vivo assessments of cell function. The levels of phosphorylated PI3K/AKT (p-PI3K/p-AKT) in LPAR1 knockdown and LPAR1-overexpressing cells were detected.

Results

The H-scores for LPAR1 staining in the lymphatic metastatic and recurrent lesions were noticeably higher than in the primary tumor lesions from the same patients (P = 0.024/0.031). High LPAR1 expression was associated with worse progression-free survival and overall survival (P = 0.017/0.039). Biological functions in vitro, including invasion, migration, and proliferation, and tumor formation in vivo were decreased in the LPAR1-silenced cells (all P < 0.05). These cellular functions were significantly increased in the LPAR1-overexpressing cells in vitro and in vivo (all P < 0.05). The levels of p-PI3K and p-AKT were significantly decreased in the LPAR1 knockdown cells and significantly increased in the LPAR1-overexpressing cells (all P < 0.05).

Conclusions

Higher levels of the LPAR1 protein were associated with a poor prognosis. LPAR1 plays essential roles in the invasion, migration, and proliferation of heterogeneous subsets of OSC cell lines and the development of ITH of OSC, possibly by modulating the activity of the PI3K/AKT signaling pathway.

Lipid metabolism and Calcium signaling in epithelial ovarian cancer

Epithelial Ovarian cancer (EOC) is the deadliest gynecologic malignancy and represents the fifth leading cause of all cancer-related deaths in women. The majority of patients are diagnosed at an advanced stage of the disease that has spread beyond the ovaries to the peritoneum or to distant organs (stage FIGO III-IV) with a 5-year overall survival of about 29%. Consequently, it is necessary to understand the pathogenesis of this disease. Among the factors that contribute to cancer development, lipids and ion channels have been described to be associated to cancerous diseases particularly in breast, colorectal and prostate cancers. Here, we reviewed the literature data to determine how lipids or lipid metabolites may influence EOC risk or progression. We also highlighted the role and the expression of the calcium (Ca²⁺) and calcium-activated potassium (KCa) channels in EOC and how lipids might regulate them. Although lipids and some subclasses of nutritional lipids may be associated to EOC risk, lipid metabolism of LPA (lysophosphatidic acid) and AA (arachidonic acid) emerges as an important signaling network in EOC. Clinical data showed that they are found at high concentrations in EOC patients and in vitro and in vivo studies referred to them as triggers of the Ca²⁺entry in the cancer cells inducing their proliferation, migration or drug resistance. The cross-talk between lipid mediators and Ca²⁺ and/or KCa channels needs to be elucidated in EOC in order to facilitate the understanding of its outcomes and potentially suggest novel therapeutic strategies including treatment and prevention.

Upregulated microRNA-15b alleviates ovarian cancer through inhitbition of the PI3K/Akt pathway by targeting LPAR3

Ovarian cancer characterizes as the fourth leading consequence of death associated with cancer for women. Accumulating evidence underscores the vital roles of microRNAs (miRNAs) in preventing ovarian cancer development. Besides, induction of the phosphatidylinositol-3 kinase/serine/threonine kinase (PI3K/Akt) pathway associated with the ovarian cancer cell migration and invasion. The study aims to examine the effects of miR-15b on the proliferation, apoptosis, and senescence of human ovarian cancer cells by binding to lysophosphatidic acid receptor 3 (LPAR3) with the involvement of the PI3K/Akt pathway. The positive expression of LPAR3 protein was detected by immunohistochemistry. Then the interaction between miR-15b and LPAR3 was examined. The possible role of miR-15b in ovarian cancer was explored using gain- and loss-of-function experiments. Subsequently, the functions of miR-15b on PI3K/Akt pathway, proliferation, migration, invasion, senescence and apoptosis of ovarian cancer cells were assessed. Furthermore, in vivo tumorigenicity assay in nude mice was performed. LPAR3 was overexpressed, whereas miR-15b was poorly expressed in ovarian cancer tissues. LPAR3 is a direct target of miR-15b. Restored miR-15b promoted Bax expression, apoptosis, and senescence, inhibited expression of LPAR3 and Bcl-2, the extent of PI3K and Akt phosphorylation, as well as ovarian cancer cell proliferation, migration, and invasion. Further, tumor growth was observed to be prevented by miR-15b overexpression. Collectively, our study demonstrates that miR-15b represses the proliferation and drives the senescence and apoptosis of ovarian cancer cells through the suppression of LPAR3 and the PI3K/Akt pathway, highlighting an antitumorigenic role of miR-15b.

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.

Piwi like RNA-mediated gene silencing 1 gene as a possible major player in gastric cancer

AIM

To establish a permanent piwi like RNA-mediated gene silencing 1 (PIWIL1) gene knockout in AGP01 gastric cancer cell line using CRISPR-Cas9 system and analyze phenotypic modifications as well as gene expression alterations.

METHODS

CRISPR-Cas9 system used was purchased from Dharmacon GE Life Sciences (Lafayette, CO, United States) and permanent knockout was performed according to manufacturer’s recommendations. Wound-healing assay was performed to investigate the effect of PIWIL1 knockout on migration capability of cells and Boyden chamber invasion assay was performed to investigate the effect on invasion capability. For the gene expression analysis, a one-color microarray-based gene expression analysis kit (Agilent Technologies, Santa Clara, CA, United States) was used according to the protocol provided by the manufacturer.

RESULTS

PIWIL1 gene knockout caused a significant decrease in AGP01 migration capacity as well as a significant decrease in cell invasiveness. Moreover, functional analysis based on grouping of all differentially expressed mRNAs identified a total of 35 genes (5 up-regulated and 30 down-regulated) encoding proteins involved in cellular invasion and migration. According to current literature, 9 of these 35 genes (DOCK2, ZNF503, PDE4D, ABL1, ABL2, LPAR1, SMAD2, WASF3 and DACH1) are possibly related to the mechanisms used by PIWIL1 to promote carcinogenic effects related to migration and invasion, since their functions are consistent with the changes observed (being up- or down-regulated after knockout).

CONCLUSION

Taken together, these data reinforce the idea that PIWIL1 plays a crucial role in the signaling pathway of gastric cancer, regulating several genes involved in migration and invasion processes; therefore, its use as a therapeutic target may generate promising results in the treatment of gastric cancer.

Role of tumor microenvironment in the pathobiology of ovarian cancer: Insights and therapeutic opportunities

Ovarian cancer is the fifth most common cancer affecting women and at present, stands as the most lethal gynecologic malignancy. The poor disease outcome is due to the nonspecific symptoms and the lack of effective treatment at advanced stages. Thus, it is of utmost importance to understand ovarian carcinoma through several lenses and to dissect the role that the unique peritoneal tumor microenvironment plays in ovarian cancer progression and metastasis. This review seeks to highlight several determinants of this unique tumor microenvironment, their influence on disease outcome and ongoing clinical trials targeting these determinants.

Lysophosphatidic acid triggers cathepsin B-mediated invasiveness of human endometriotic cells

Extracellular lysophosphatidic acid (LPA) and the G-protein-coupled LPA receptors (LPAR) are involved in cell migration and invasion and found in the human endometrium. However, underlying mechanisms resulting in cellular invasion have been rarely investigated. We used stromal endometrial T-HESC, epithelial endometriotic 12Z, 49Z and Ishikawa cells. Interestingly, proliferation of T-HESC cells was strongly increased after LPA treatment, whereas the epithelial cell lines only showed a moderate increase. LPA increased invasion of 12Z and 49Z strongly and significantly. The LPAR inhibitor Ki16425 (LPAR1/3) attenuated significantly LPA-induced invasiveness of 12Z, which was confirmed by LPAR1 and LPAR3 siRNAs, showing that both LPA receptors contribute to invasiveness of 12Z cells. Investigation of cell invasion with an antibody-based protease array revealed mainly differences in cathepsins and especially cathepsin B between 12Z compared to the less invasive Ishikawa. Stimulation with LPA showed a time- and dose-dependent increased secretion of cathepsin B which was inhibited by the Gq inhibitor YM-254890 and Gi/o inhibitor pertussis toxin in the 12Z cells, again highlighting the importance of LPAR1/3. The activity of intracellular and secreted cathepsin B was significantly upregulated in LPA-treated samples. Inhibition of cathepsin B with the specific inhibitor CA074 significantly reduced LPA-increased invasion of 12Z. Our results reveal a novel role of LPA-mediated secretion of cathepsin B which stimulated invasion of endometriotic epithelial cells mainly via LPAR1 and LPAR3. These findings may deepen our understanding how endometriotic cells invade into ectopic sites, and provide new insights into the role of LPA and cathepsin B in cellular invasion.

The Role of Inflammation and Inflammatory Mediators in the Development, Progression, Metastasis, and Chemoresistance of Epithelial Ovarian Cancer

Inflammation plays a role in the initiation and development of many types of cancers, including epithelial ovarian cancer (EOC) and high grade serous ovarian cancer (HGSC), a type of EOC. There are connections between EOC and both peritoneal and ovulation-induced inflammation. Additionally, EOCs have an inflammatory component that contributes to their progression. At sites of inflammation, epithelial cells are exposed to increased levels of inflammatory mediators such as reactive oxygen species, cytokines, prostaglandins, and growth factors that contribute to increased cell division, and genetic and epigenetic changes. These exposure-induced changes promote excessive cell proliferation, increased survival, malignant transformation, and cancer development. Furthermore, the pro-inflammatory tumor microenvironment environment (TME) contributes to EOC metastasis and chemoresistance. In this review we will discuss the roles inflammation and inflammatory mediators play in the development, progression, metastasis, and chemoresistance of EOC.

Activity and clinical relevance of autotaxin and lysophosphatidic acid pathways in high-grade serous carcinoma

The aim of this study was to analyze the expression, biological role and clinical relevance of autotaxin (ATX), the enzyme synthetizing lysophosphatidic acid (LPA), and LPA receptors (LPAR) in high-grade serous carcinoma (HGSC). mRNA expression by qRT-PCR of LPAR1-6 was analyzed in 155 HGSC specimens (88 effusions, 67 solid lesions). ATX mRNA expression was analyzed in 97 specimens. ATX, ERK, and AKT protein expression was studied by Western blotting. LPAR2 mRNA was overexpressed in HGSC cells in effusions compared to solid lesions, with opposite findings for LPAR3 and LPAR6 mRNA and ATX protein. Higher LPAR1 levels were significantly related to longer overall survival (OS) in pre-chemotherapy effusions (p = 0.027). Conversely, higher expression of LPAR1, LPAR2, and LPAR5 in post-chemotherapy effusions was significantly associated with shorter OS (p = 0.037, p = 0.025 and p = 0.021, respectively) and progression-free survival (PFS) (p < 0.001, p = 0.007 and p < 0.001, respectively) in univariate survival analysis. LPAR1 mRNA expression was an independent prognosticator of OS in patients with pre-chemotherapy effusions and PFS in patients with post-chemotherapy effusions (p = 0.013 both). In conclusion, LPAR mRNA and ATX protein levels are anatomic site-dependent in HGSC and the former are informative of disease outcome.

Limited fibrosis accompanies triple-negative breast cancer metastasis in multiple model systems and is not a preventive target

The lysophosphatidic acid receptor 1 (LPAR1) is mechanistically implicated in both tumor metastasis and tissue fibrosis. Previously, metastasis was increased when fulminant fibrosis was first induced in mice, suggesting a direct connection between these processes. The current report examined the extent of metastasis-induced fibrosis in breast cancer model systems, and tested the metastasis preventive efficacy and fibrosis attenuation of antagonists for LPAR1 and Idiopathic Pulmonary Fibrosis (IPF) in breast and ovarian cancer models. Staining analysis demonstrated only focal, low-moderate levels of fibrosis in lungs from eleven metastasis model systems. Two orally available LPAR1 antagonists, SAR100842 and EPGN9878, significantly inhibited breast cancer motility to LPA in vitro. Both compounds were negative for metastasis prevention and failed to reduce fibrosis in the experimental MDA-MB-231T and spontaneous murine 4T1 in vivo breast cancer metastasis models. SAR100842 demonstrated only occasional reductions in invasive metastases in the SKOV3 and OVCAR5 ovarian cancer experimental metastasis models. Two approved drugs for IPF, nintedanib and pirfenidone, were investigated. Both were ineffective at preventing MDA-MB-231T metastasis, with no attenuation of fibrosis. In summary, metastasis-induced fibrosis is only a minor component of metastasis in untreated progressive breast cancer. LPAR1 antagonists, despite in vitro evidence of specificity and efficacy, were ineffective in vivo as oral agents, as were approved IPF drugs. The data argue against LPAR1 and fibrosis as monotherapy targets for metastasis prevention in triple-negative breast cancer and ovarian cancer.

Role of tumor microenvironment in ovarian cancer pathobiology

Ovarian cancer is the fifth most common cancer affecting the female population and at present, stands as the most lethal gynecologic malignancy. Poor prognosis and low five-year survival rate are attributed to nonspecific symptoms and below par diagnostic criteria at early phases along with a lack of effective treatment at advanced stages. It is thus of utmost importance to understand ovarian carcinoma through several lenses including its molecular pathogenesis, epidemiology, histological subtypes, hereditary factors, diagnostic approaches and methods of treatment. Above all, it is crucial to dissect the role that the unique peritoneal tumor microenvironment plays in ovarian cancer progression and metastasis. This review seeks to highlight several important aspects of ovarian cancer pathobiology as a means to provide the necessary background to approach ovarian malignancies in the future.

LPAR2 and LPAR4 are the Main Receptors Responsible for LPA Actions in Ovarian Endometriotic Cysts

Endometriosis has been considered as an estrogen (E2)-dependent and progesterone (P4)-resistant disease. On the other hand, lysophosphatidic acid (LPA) has been suggested as a significant modulator of ovarian pathology, acting via both LPA levels and LPA receptor (LPAR) upregulation. Therefore, the objective of the present study was to evaluate LPA concentration as well as LPARs, autotaxin (ATX), and phospholipase A2 (PLA2) expression in ovarian endometriotic cysts and normal endometrium with correlation of the expression of E2 and P4 receptors in endometriotic cysts. The analyses were carried out using the tissues derived from 37 patients with ovarian endometriosis and 20 endometrial samples collected from women without endometriosis were used as a control. We found that ovarian endometriotic cysts are a site of LPA synthesis due to the presence of enzymes involved in LPA synthesis in the tissue. Additionally, when we compared endometriotic cysts versus normal endometrium, we were able to show overexpression of 3 from 6 examined LPARs and both enzymes responsible for LPA synthesis in endometriotic cysts. Finally, we found the correlations between LPARs, ATX, and PLA2 and the expression of E2 and P4 receptors in endometriotic cysts. Owing to the high LPAR2 and LPAR4 transcript and protein expression in endometriotic ovarian cysts and positive correlations of both these receptors with the PR-B and ERβ, respectively, those receptors seem to be the most promising predictors of the endometriotic cysts as well as the main receptors responsible for LPA action in the ovarian endometriosis.

Identification and functional analyses of differentially expressed metabolites in early stage endometrial carcinoma

Diagnosis of endometrial cancer is primarily based on symptoms and imaging, with early-stage disease being difficult to diagnose. Therefore, development of potential diagnostic biomarkers is required. Metabolomics, a quantitative measurement of the dynamic metabolism in living systems, can be applied to determine metabolite profiles in different disease states. Here, serum metabolomics was performed in 46 early stage endometrial cancer patients and 46 healthy volunteers. In addition, the effect of identified metabolites on tumor cell behavior (invasion, migration, proliferation, apoptosis and autophagy) was examined in endometrial cancer cell lines. Compared with controls, phenylalanine, indoleacrylic acid (IAA), phosphocholine and lyso-platelet-activating factor-16 (lyso-PAF) were differentially detected in patients. Functional analyses demonstrated that IAA, PAF and phenylalanine all dose-dependently inhibited tumor cell invasion and migration, and suppressed cell proliferation. PAF also induced tumor cell apoptosis and autophagy, while phenylalanine had no effect on apoptosis or autophagy. IAA triggered apoptosis and had a biphasic effect on autophagy: inhibiting autophagy with doses <1 mmol/L but inducing at 1 mmol/L. Interestingly, the alterations in proliferation, apoptosis and autophagy caused by 1 mmol/L IAA, were all reversed by the concomitant treatment of tryptophan (100 μmol/L). Phosphocholine inhibited tumor cell invasion and migration, and promoted cell proliferation and autophagy, all in a dose-dependent manner. Phosphocholine also protected cells from TNF-α-induced apoptosis. In conclusion, 4 serum metabolites were identified by serum metabolomics in endometrial cancer patients and functional analyses suggested that they may play roles in modulation of tumor cell behavior, although their exact mode of action still needs to be determined.