Lipoxin A4 and its analogue suppress the tumor growth of transplanted H22 in mice: the role of antiangiogenesis

The Role of Specialized Pro-Resolving Lipid Mediators in Inflammation-Induced Carcinogenesis

Cancer is a process involving cell mutation, increased proliferation, invasion, and metastasis. Over the years, this condition has represented one of the most concerning health problems worldwide due to its significant morbidity and mortality. At present, the incidence of cancer continues to grow exponentially. Thus, it is imperative to open new avenues in cancer research to understand the molecular changes driving DNA transformation, cell-to-cell interaction derangements, and immune system surveillance decay. In this regard, evidence supports the relationship between chronic inflammation and cancer. In light of this, a group of bioactive lipids derived from polyunsaturated fatty acids (PUFAs) may have a position as novel anti-inflammatory molecules known as the specialized pro-resolving mediators (SPMs), a group of pro-resolutive inflammation agents that could improve the anti-tumor immunity. These molecules have the potential role of chemopreventive and therapeutic agents for various cancer types, and their effects have been documented in the scientific literature. Thus, this review objective centers around understanding the effect of SPMs on carcinogenesis and their potential therapeutic effect.

Formyl peptide receptor 2 is an emerging modulator of inflammation in the liver

Formyl peptide receptors (FPRs), which are seven-membrane G-protein coupled receptors, recognize chemotactic signals to protect hosts from pathogenic infections and mediate inflammatory responses in the body. There are three isoforms of FPRs in humans-FPR1, FPR2, and FPR3-and they bind to N-formyl peptides, except FPR3, and to various endogenous agonists. Among FPR family members, FPR2 has a lower affinity for N-formyl peptides than FPR1 and binds with a wide range of endogenous or exogenous agonists. Thus, FPR2 is considered the most ambiguous member. Accumulating evidence has shown that FPR2 is involved in the host's defense against bacterial infection and inflammation in liver diseases, such as nonalcoholic fatty liver disease, liver fibrosis, and liver cancer, suggesting the pathophysiological relevance of FPR2 to the liver. However, FPR2 has been shown to promote or suppress inflammation, depending on the type of FPR2-expressing cell and FPR2-bound ligands in the liver. Therefore, it is important to understand FPR2's function per se and to elucidate the mechanism underlying immunomodulation initiated by ligand-activated FPR2 before suggesting FPR2 as a novel therapeutic agent for liver diseases. In this review, up-to-date knowledge of FPR2, with general information on the FPR family, is provided. We shed light on the dual action of FPR2 in the liver and discuss the hepatoprotective roles of FPR2 itself and FPR2 agonists in mediating anti-inflammatory responses.

The role of oxylipins in NSAID-exacerbated respiratory disease (N-ERD)

Nonsteroidal anti-inflammatory drug (NSAID)-exacerbated respiratory disease (N-ERD) is characterized by nasal polyp formation, adult-onset asthma, and hypersensitivity to all cyclooxygenase-1 (COX-1) inhibitors. Oxygenated lipids are collectively known as oxylipins and are polyunsaturated fatty acids (PUFA) oxidation products. The most extensively researched oxylipins being the eicosanoids formed from arachidonic acid (AA). There are four major classes of eicosanoids including leukotrienes, prostaglandins, thromboxanes, and lipoxins. In N-ERD, the underlying inflammatory process of the upper and lower respiratory systems begins and occurs independently of NSAID consumption and is due to the overproduction of cysteinyl leukotrienes. Leukotriene mediators all induce edema, bronchoconstriction, and airway mucous secretion. Thromboxane A2 is a potent bronchoconstrictor and induces endothelial adhesion molecule expression. Elevated Prostaglandin D2 metabolites lead to vasoconstriction, additionally impaired up-regulation of prostaglandin E2 leads to symptoms seen in N-ERD as it is essential for maintaining homeostasis of inflammatory responses in the airway and has bronchoprotective and anti-inflammatory effects. A characteristic feature of N-ERD is diminished lipoxin levels, this decreased capacity to form endogenous mediators with anti-inflammatory properties could facilitate local inflammatory response and expose bronchial smooth muscle to relatively unopposed actions of broncho-constricting substances. Treatment options, such as leukotriene modifying agents, aspirin desensitization, biologic agents and ESS, appear to influence eicosanoid pathways, however more studies need to be done to further understand the role of oxylipins. Besides AA-derived eicosanoids, other oxylipins may also pay a role but have not been sufficiently studied. Identifying pathogenic N-ERD mechanism is likely to define more effective treatment targets.

BML-111, the agonist of lipoxin A4, suppresses epithelial-mesenchymal transition and migration of MCF-7 cells via regulating the lipoxygenase pathway

Introduction: Aberrant epithelial-mesenchymal transition (EMT) and migration frequently occur during tumour progression. BML-111, an analogue of lipoxin A4, has been implicated in inflammation in cancer research. Methods: 3-(4,5-Dimethyl-2-thiazolyl)-2,5-diphenyl-2H-tetrazolium bromide (MTT) assay, western blot, Reverse Transcription Polymerase Chain Reaction (RT-PCR), transwell assay, immunofluorescence, and immunohistochemistry were conducted in this study. Results: In vitro experiments revealed that BML-111 inhibited EMT and migration in CoCl2-stimulated MCF-7 cells. These effects were achieved by inhibiting MMP-2 and MMP-9, which are downregulated by 5-lipoxygenase (5-LOX). Moreover, BML-111 inhibited EMT and migration of breast cancer cells in BALB/c nude mice inoculated with MCF-7 cells. Conclusion: Our results suggest that BML-111 may be a potential therapeutic drug for breast cancer and that blocking the 5-LOX pathway could be a possible approach for mining effective drug targets.

Therapeutic potential of WKYMVm in diseases

The synthetic hexapeptide WKYMVm, screened from a synthetic peptide library, has been identified as an agonist of FPRs with the strongest activating effect on FPR2. WKYMVm plays an anti-inflammatory role in most inflammatory diseases by increasing the chemotaxis of phagocytes and regulating the secretion of inflammatory factors. WKYMVm can inhibit or promote the progression of different types of tumors, which depends on the regulation of WKYMVm on various components such as immune cells, inflammatory factors, chemokines, and tumor epithelial cells. Another major function of WKYMVm is to promote angiogenesis, which is reflected in its therapeutic value in ischemic diseases, wound healing and bone repair. In addition to the above functions, this paper also reviews the effects of WKYMVm on fibrosis, insulin resistance, osteolytic diseases and neurodegenerative diseases. By summarizing related studies, this review can increase people’s comprehensive understanding of WKYMVm, promote its broad and in-depth research, and help to exert its therapeutic value as soon as possible.

The probiotic Lactobacillus rhamnosus GG (LGG) restrains the angiogenic potential of colorectal carcinoma cells by activating a pro-resolving program via formyl peptide receptor 1

Formyl peptide receptors (FPR1, FPR2 and FPR3) are innate immune sensors of pathogen and commensal bacteria and have a role in colonic mucosa homeostasis. We identified FPR1 as a tumour suppressor in gastric cancer cells due to its ability to sustain an inflammation resolution response with antiangiogenic potential. Here, we investigate whether FPR1 exerts similar functions in colorectal carcinoma (CRC) cells. Since it has been shown that the commensal bacterium Lactobacillus rhamnosus GG (LGG) can promote intestinal epithelial homeostasis through FPR1, we explored the possibility that it could induce proresolving and antiangiogenic effects in CRC cells. We demonstrated that pharmacologic inhibition or genetic deletion of FPR1 in CRC cells caused a reduction of proresolving mediators and a consequent upregulation of angiogenic factors. The activation of FPR1 mediates opposite effects. Proresolving, antiangiogenic and homeostatic functions were also observed upon treatment of CRC cells with supernatant of LGG culture, but not of other lactic acid or nonprobiotic bacteria (i.e. Bifidobacterium bifidum or Escherichia coli). These activities of LGG are dependent on FPR1 expression and on the subsequent MAPK signalling activation. Thus, the innate immune receptor FPR1 could be a regulator of the balance between microbiota, inflammation and cancer in CRC models.

The Impact of Resolution of Inflammation on Tumor Microenvironment: Exploring New Ways to Control Cancer Progression

Non-resolving inflammation is an enabling feature of cancer. A novel super-family of lipid mediators termed Specialized Pro-resolving Mediators (SPMs) have a role as bioactive molecules mediating the resolution of inflammation in cancer biology. SPMs are derived from ω-3 and ω-6 polyunsaturated fatty acids through the activity of lipoxygenases. SPMs have been described to directly modulate cancer progression by interfering with the epithelial to mesenchymal transition and invasion of cancer cells. SPMs have also been demonstrated to act on several components of the tumor microenvironment (TME). Consistently with their natural immunomodulatory and anti-inflammatory properties, SPMs are able to reprogram macrophages to favor phagocytosis of cell debris, which are an important source of pro-inflammatory and pro-angiogenic signals; sustain a direct cytotoxic immune response against cancer cells; stimulate neutrophils anti-tumor activities; and inhibit the development of regulatory T and B cells, thus indirectly leading to enhanced anti-tumor immunity. Furthermore, the resolution pathways exert crucial anti-angiogenic functions in lung, liver, and gastrointestinal cancers, and inhibit cancer-associated fibroblast differentiation and functions in hepatocellular carcinoma and pancreatic cancer. The present review will be focused on the potential protective effects of resolution pathways against cancer, exerted by modulating different components of the TME.

Pro-Resolving Factor Administration Limits Cancer Progression by Enhancing Immune Response Against Cancer Cells

Cancers are consequences of cellular dysfunction leading to an aberrant cellular multiplication and proliferation, subsequently yielding metastasis formation. Inflammatory reaction, with immune cell recruitment, is the main defense against precancerous lesions. However, an inflammatory environment also favors cancer cell progression, with cancer cell evasion from immune surveillance, leading to cancer development. Current therapeutic strategies enhance this natural immune response in order to restore immunosurveillance. The variety of these strategies is a predominant source of inflammatory mediators used by cancer cells to grow, differentiate, and migrate, therefore encouraging metastasis formation. For this reason, during cancer progression, limiting inflammation appears to be an innovative strategy to avoid the escape of cancer cells and potentially enhance the efficacy of antitumor therapies. Thus, this study aims to investigate the impact of administering pro-resolving factors (SuperMApo® drug candidate), which are inducers of inflammation resolution, in the framework of cancer treatment. We have observed that administering pro-resolving mediators issued from apoptotic cell efferocytosis by macrophages controlled peritoneal cancer progression by limiting cancer cell dissemination to the blood and mesenteric lymph nodes. This observation has been linked to an increase of macrophage mobilization in both peritoneal cavity and mesenteric lymph nodes. This control is associated to a restricted immunosuppressive myeloid cell circulation and to an IFN-γ-specific anti-tumor T-cell response. Altogether, these results suggest that administering proresolving factors could provide a new additional therapeutic alternative to control cancer progression.

NAP1051, a Lipoxin A4 Biomimetic Analogue, Demonstrates Antitumor Activity Against the Tumor Microenvironment

Resolving tumor-associated inflammation in the tumor microenvironment (TME) may promote antitumor effects. Lipoxin A4 (LXA4) is a short-lived endogenous bioactive lipid with potent anti-inflammatory and pro-resolving properties. Here, a biomimetic of LXA4, NAP1051, was shown to have LXA4-like in vitro properties and antitumor activity in colorectal cancer xenograft models. NAP1051 inhibited neutrophil chemotaxis toward fMLP and dose-dependently promoted dTHP-1 efferocytosis which was equipotent to aspirin-triggered lipoxin A4 (ATLA). In dTHP-1 cells, NAP1051 induced strong phosphorylation on ERK1/2 and AKT similar to formyl peptide receptor 2 (FPR2/ALX) agonists. In two mouse xenograft colorectal cancer models, NAP1051 significantly inhibited tumor growth when given orally at 4.8 to 5 mg/kg/day. Flow cytometric analyses showed that NAP1051 reduced splenic and intratumoral neutrophil and myeloid-derived suppressor cell populations, which correlated to the antitumor effect. In addition, NAP1051 reduced NETosis in the TME while stimulating T-cell recruitment. Overall, these results show that NAP1051 possesses key lipoxin-like properties and has antitumor activity against colorectal cancer via modulation of neutrophils and NETosis in the TME.

Specialized Pro-Resolving Mediators Mitigate Cancer-Related Inflammation: Role of Tumor-Associated Macrophages and Therapeutic Opportunities

Inflammation is a fundamental physiological response orchestrated by innate immune cells to restore tissue homeostasis. Specialized pro-resolving mediators (SPMs) are involved in active resolution of inflammation but when inflammation is incomplete, chronic inflammation creates a favorable environment that fuels carcinogenesis and cancer progression. Conventional cancer therapy also strengthens cancer-related inflammation by inducing massive tumor cell death that activate surrounding immune-infiltrating cells such as tumor-associated macrophages (TAMs). Macrophages are key actors of both inflammation and its active resolution due to their plastic phenotype. In line with this high plasticity, macrophages can be hijacked by cancer cells to support tumor progression and immune escape, or therapy resistance. Impaired resolution of cancer-associated inflammation supported by TAMs may thus reinforces tumor progression. From this perspective, recent evidence suggests that stimulating macrophage's pro-resolving functions using SPMs can promote inflammation resolution in cancer and improve anticancer treatments. Thus, TAMs' re-education toward an antitumor phenotype by using SPMs opens a new line of attack in cancer treatment. Here, we review SPMs' anticancer capacities with special attention regarding their effects on TAMs. We further discuss how this new therapeutic approach could be envisioned in cancer therapy.

Aspirin Actions in Treatment of NSAID-Exacerbated Respiratory Disease

Non-steroidal Anti-inflammatory drugs (NSAID)-exacerbated respiratory disease (N-ERD) is characterized by nasal polyposis, chronic rhinosinusitis, adult-onset asthma and hypersensitive reactions to cyclooxygenase-1 (COX-1) inhibitors. Among the available treatments for this disease, a combination of endoscopic sinus surgery followed by aspirin desensitization and aspirin maintenance therapy has been an effective approach. Studies have shown that long-term aspirin maintenance therapy can reduce the rate of nasal polyp recurrence in patients with N-ERD. However, the exact mechanism by which aspirin can both trigger and suppress airway disease in N-ERD remains poorly understood. In this review, we summarize current knowledge of aspirin effects in N-ERD, cardiovascular disease, and cancer, and consider potential mechanistic pathways accounting for the effects of aspirin in N-ERD.

Lipid mediator lipoxin A4 and its analog BML-111 exert antitumor effects in melanoma

Background

LipoxinA4 (LXA4) is an anti-inflammatory lipid mediator which was recently proposed to have antitumor potential. However, the therapeutic effect of LXA4 in melanoma is still unclear. This work aimed to investigate the function of LXA4 and its analog in melanoma invasion through in vivo and in vitro experiments.

Methods

The expression of the LXA4 receptor (ALXR) was detected in melanoma tissues and A375 human melanoma cells, using benign melanocytic nevi tissues and human melanocytes as negative controls, respectively. The invasive and apoptotic abilities of A375 cells in the presence or absence of LXA4 were examined by cell invasion assay and flow cytometric analysis. Finally, mice melanoma models were established, and the antitumor effects of BML-111 [5(S), 6(R)-7-trihydroxymethyl heptanoate], an agonist of ALXR, were examined in vivo.

Results

ALXR was abundantly expressed in human melanoma tissues. The ALXR messenger RNA (mRNA) and protein expression levels were higher in A375 melanoma cells than in the controls (P<0.05). LXA4 could significantly attenuate the invasion ability of A375 cells (P<0.05). This trend was further enhanced by BML-111, which tended to control the tumor development in A375 melanoma models.

Conclusions

LXA4 and its analog BML-111 exert antitumor effects in vivo and in vitro, and may be potential therapeutic options for patients with invasive melanoma.

Carcinogenesis: Failure of resolution of inflammation?

Inflammation in the tumor microenvironment is a hallmark of cancer and is recognized as a key characteristic of carcinogens. However, the failure of resolution of inflammation in cancer is only recently being understood. Products of arachidonic acid and related fatty acid metabolism called eicosanoids, including prostaglandins, leukotrienes, lipoxins, and epoxyeicosanoids, critically regulate inflammation, as well as its resolution. The resolution of inflammation is now appreciated to be an active biochemical process regulated by endogenous specialized pro-resolving lipid autacoid mediators which combat infections and stimulate tissue repair/regeneration. Environmental and chemical human carcinogens, including aflatoxins, asbestos, nitrosamines, alcohol, and tobacco, induce tumor-promoting inflammation and can disrupt the resolution of inflammation contributing to a devastating global cancer burden. While mechanisms of carcinogenesis have focused on genotoxic activity to induce mutations, nongenotoxic mechanisms such as inflammation and oxidative stress promote genotoxicity, proliferation, and mutations. Moreover, carcinogens initiate oxidative stress to synergize with inflammation and DNA damage to fuel a vicious feedback loop of cell death, tissue damage, and carcinogenesis. In contrast, stimulation of resolution of inflammation may prevent carcinogenesis by clearance of cellular debris via macrophage phagocytosis and inhibition of an eicosanoid/cytokine storm of pro-inflammatory mediators. Controlling the host inflammatory response and its resolution in carcinogen-induced cancers will be critical to reducing carcinogen-induced morbidity and mortality. Here we review the recent evidence that stimulation of resolution of inflammation, including pro-resolution lipid mediators and soluble epoxide hydrolase inhibitors, may be a new chemopreventive approach to prevent carcinogen-induced cancer that should be evaluated in humans.

BML-111, the lipoxin A4 agonist, modulates VEGF or CoCl2-induced migration, angiogenesis and permeability in tumor-derived endothelial cells

Tumor angiogenesis plays a vital role in carcinogenesis, cancer progression, and metastasis. Lipoxin A₄ (LXA₄) is an endogenously-produced family of effective anti-inflammatory with a potent inhibitory effect on angiogenesis. However, BML-111, a LXA₄ agonist, its governing tumor-derived endothelial cells (Td-EC) mechanisms remain unknown. In the present study, we utilized VEGF or CoCl₂ to mimic tumor microenvironment in vitro to study the effect of BML-111 on angiogenesis and permeability of Td-EC, and preliminarily explore its specific mechanism. Data suggested that BML-111 inhibited viability, migration and angiogenesis in VEGF or CoCl₂-treated Td-EC by modulating MMP2/9-TIMP1, and decreasing the production of HIF-1α and COX-2 level. In addition, we observed that BML-111 inhibited Td-EC permeability induced by VEGF or CoCl₂, through the stabilization of VE-cadherin/β-catenin-dependent adherens junctions and TRPC1 pathway. Nevertheless, these effects could be blocked by BOC-2 which was the specific inhibitor of FPR2/ALX (the receptor of LXA₄).These results suggest that BML-111 may have inhibitory effects on VEGF or CoCl₂-induced migration, angiogenesis and permeability in tumor-derived endothelial cells.

Endothelial activation and dysfunction in COVID-19: from basic mechanisms to potential therapeutic approaches

On 12 March 2020, the outbreak of coronavirus disease 2019 (COVID-19) was declared a pandemic by the World Health Organization. As of 4 August 2020, more than 18 million confirmed infections had been reported globally. Most patients have mild symptoms, but some patients develop respiratory failure which is the leading cause of death among COVID-19 patients. Endothelial cells with high levels of angiotensin-converting enzyme 2 expression are major participants and regulators of inflammatory reactions and coagulation. Accumulating evidence suggests that endothelial activation and dysfunction participate in COVID-19 pathogenesis by altering the integrity of vessel barrier, promoting pro-coagulative state, inducing endothelial inflammation, and even mediating leukocyte infiltration. This review describes the proposed cellular and molecular mechanisms of endothelial activation and dysfunction during COVID-19 emphasizing the principal mediators and therapeutic implications.

Specialized Proresolving Mediators Overcome Immune Suppression Induced by Exposure to Secondhand Smoke

Tobacco smoke exposure is associated with multiple diseases including, respiratory diseases like asthma and chronic obstructive pulmonary disease. Tobacco smoke is a potent inflammatory trigger and is immunosuppressive, contributing to increased susceptibility to pulmonary infections in smokers, ex-smokers, and vulnerable populations exposed to secondhand smoke. Tobacco smoke exposure also reduces vaccine efficacy. Therefore, mitigating the immunosuppressive effects of chronic smoke exposure and improving the efficacy of vaccinations in individuals exposed to tobacco smoke, is a critical unmet clinical problem. We hypothesized that specialized proresolving mediators (SPMs), a class of immune regulators promoting resolution of inflammation, without being immunosuppressive, and enhancing B cell Ab responses, could reverse the immunosuppressive effects resulting from tobacco smoke exposure. We exposed mice to secondhand smoke for 8 wk, followed by a period of smoke exposure cessation, and the mice were immunized with the P6 lipoprotein from nontypeable Haemophilus influenzae, using 17-HDHA and aspirin-triggered-resolvin D1 (AT-RvD1) as adjuvants. 17-HDHA and AT-RvD1 used as adjuvants resulted in elevated serum and bronchoalveolar lavage levels of anti-P6-specific IgG and IgA that were protective, with immunized mice exhibiting more rapid bacterial clearance upon challenge, reduced pulmonary immune cell infiltrates, reduced production of proinflammatory cytokines, and less lung-epithelial cell damage. Furthermore, the treatment of mice with AT-RvD1 during a period of smoke-cessation further enhanced the efficacy of SPM-adjuvanted P6 vaccination. Overall, SPMs show promise as novel vaccine adjuvants with the ability to overcome the tobacco smoke-induced immunosuppressive effects.

RNA-Seq analysis of the guppy immune response against Gyrodactylus bullatarudis infection

Gyrodactylids are ubiquitous ectoparasites of teleost fish, but our understanding of the host immune response against them is fragmentary. Here, we used RNA-Seq to investigate genes involved in the primary response to infection with Gyrodactylus bullatarudis on the skin of guppies, Poecilia reticulata, an important evolutionary model, but also one of the most common fish in the global ornamental trade. Analysis of differentially expressed genes identified several immune-related categories, including IL-17 signalling pathway and Th17 cell differentiation, cytokine-cytokine receptor interaction, chemokine signalling pathway, NOD-like receptor signalling pathway, natural killer cell-mediated cytotoxicity and pathways involved in antigen recognition, processing and presentation. Components of both the innate and the adaptive immune responses play a role in response to gyrodactylid infection. Genes involved in IL-17/Th17 response were particularly enriched among differentially expressed genes, suggesting a significant role for this pathway in fish responses to ectoparasites. Our results revealed a sizable list of genes potentially involved in the teleost-gyrodactylid immune response.

Lipids and cancer: Emerging roles in pathogenesis, diagnosis and therapeutic intervention

With the advent of effective tools to study lipids, including mass spectrometry-based lipidomics, lipids are emerging as central players in cancer biology. Lipids function as essential building blocks for membranes, serve as fuel to drive energy-demanding processes and play a key role as signaling molecules and as regulators of numerous cellular functions. Not unexpectedly, cancer cells, as well as other cell types in the tumor microenvironment, exploit various ways to acquire lipids and extensively rewire their metabolism as part of a plastic and context-dependent metabolic reprogramming that is driven by both oncogenic and environmental cues. The resulting changes in the fate and composition of lipids help cancer cells to thrive in a changing microenvironment by supporting key oncogenic functions and cancer hallmarks, including cellular energetics, promoting feedforward oncogenic signaling, resisting oxidative and other stresses, regulating intercellular communication and immune responses. Supported by the close connection between altered lipid metabolism and the pathogenic process, specific lipid profiles are emerging as unique disease biomarkers, with diagnostic, prognostic and predictive potential. Multiple preclinical studies illustrate the translational promise of exploiting lipid metabolism in cancer, and critically, have shown context dependent actionable vulnerabilities that can be rationally targeted, particularly in combinatorial approaches. Moreover, lipids themselves can be used as membrane disrupting agents or as key components of nanocarriers of various therapeutics. With a number of preclinical compounds and strategies that are approaching clinical trials, we are at the doorstep of exploiting a hitherto underappreciated hallmark of cancer and promising target in the oncologist's strategy to combat cancer.

BML-111 inhibits EMT, migration and metastasis of TAMs-stimulated triple-negative breast cancer cells via ILK pathway

Triple-negative breast cancer (TNBC) has a more aggressive phenotype and higher metastasis and recurrence rates than other breast cancer subtypes. The immune microenvironment and hypoxic microenvironment of breast cancer constitute the survival environment of cancer cells, which is an important environment to support cancer cells. LXA₄ and its analog, BML-111 is an important regulator of inflammatory cytokines, which provides a possible way for the treatment of inflammatory-related tumors. Here, in the in vitro experiment, we showed that BML-111 could inhibit the EMT and migration of TAMs-stimulated TNBC by down-regulating ILK as well as p-Akt and p-GSK3β. And it could prevent the formation of breast cancer cell clusters. In the in vivo experiment, BML-111 could inhibit the metastasis of 4T1 breast cancer cells. We also demonstrated that BML-111 could affect macrophages in tumor microenvironment to prevent metastasis. These results showed that BML-111 could be a possible candidate for breast cancer therapy by targeting ILK and TAMs.

Saturated Fatty Acids, MUFAs and PUFAs Regulate Ferroptosis

Apoptosis, necroptosis, autophagy, and ferroptosis are distinct mechanisms of cell death. In this issue of Cell Chemical Biology, Magtanong et al. (2019) demonstrated that exogenous monounsaturated fatty acids (MUFAs) induce a ferroptosis-resistant cell state by suppressing the accumulation of lipid peroxides and decreasing levels of oxidizable polyunsaturated fatty acids (PUFAs).

Colorectal Cancer Is Associated with a Deficiency of Lipoxin A4, an Endogenous Anti-inflammatory Mediator

Unresolved inflammation, due to insufficient production of proresolving anti-inflammatory lipid mediators, can lead to tumorigenesis. Among these mediators, lipoxin A₄ (LXA₄) has potent anti-carcinogenic properties, and may serve as key target for modulating inflammation-associated cancer like colorectal cancer. The purpose of present study was to clarify the roles of LXA₄ in colorectal cancer. We investigated the effects and underlying mechanisms of LXA₄ in colorectal cancer and its relationship with tumor-associated inflammation and immune microenvironment by employing clinical samples and mouse colorectal cancer cell line CT26-bearing tumor model as well as colorectal cancer cells. It was found that colorectal cancer is associated with dysregulation of immune microenvironment and deficiency of LXA₄ that could play different roles at different stages of tumor growth: inhibiting early but promoting late tumor growth. Analysis of peripheral immune cells in subcutaneous xenograft mice model disclosed that early LXA₄ treatment induced lymphocytes and inhibited neutrophils and monocytes, while late LXA₄ treatment induced neutrophils but inhibited lymphocytes. Detailed analysis of tumor microenvironment revealed that early LXA₄ treatment could inhibit inflammatory mediators expressions and leukocytes infiltration into tumor. Furthermore, LXA₄ could suppress the expressions of p-ERK, p-P38 and NF-κB in subcutaneous xenograft. Additionally, LXA₄ could inhibit the proliferation and migration of colorectal cancer cells, and, meanwhile, inhibit the proliferation and migration of colorectal cancer cells stimulated by activated macrophage-conditioned media. These findings suggest that colorectal cancer is associated with a deficiency of LXA₄ that could suppress colorectal cancer via modulating tumor-associated inflammation and immune microenvironment as well as inhibiting colorectal cancer cell development.

A Role for Lipid Mediators in Acute Myeloid Leukemia

In spite of therapeutic improvements in the treatment of different hematologic malignancies, the prognosis of acute myeloid leukemia (AML) treated solely with conventional induction and consolidation chemotherapy remains poor, especially in association with high risk chromosomal or molecular aberrations. Recent discoveries describe the complex interaction of immune effector cells, as well as the role of the bone marrow microenvironment in the development, maintenance and progression of AML. Lipids, and in particular omega-3 as well as omega-6 polyunsaturated fatty acids (PUFAs) have been shown to play a vital role as signaling molecules of immune processes in numerous benign and malignant conditions. While the majority of research in cancer has been focused on the role of lipid mediators in solid tumors, some data are showing their involvement also in hematologic malignancies. There is a considerable amount of evidence that AML cells are targetable by innate and adaptive immune mechanisms, paving the way for immune therapy approaches in AML. In this article we review the current data showing the lipid mediator and lipidome patterns in AML and their potential links to immune mechanisms.

Targeting lipid mediators in cancer biology

Bioactive lipids are essential components of human cells and tissues. As discussed in this review, the cancer lipidome is diverse and malleable, with the ability to promote or inhibit cancer pathogenesis. Targeting lipids within the tumor and surrounding microenvironment may be a novel therapeutic approach for treating cancer patients. Additionally, the emergence of a novel super-family of lipid mediators termed specialized pro-resolving mediators (SPMs) has revealed a new role for bioactive lipid mediators in the resolution of inflammation in cancer biology. The role of SPMs in cancer holds great promise in our understanding of cancer pathogenesis and can ultimately be used in future cancer diagnostics and therapy.

Lipoxin A4 Regulates Lipopolysaccharide-Induced BV2 Microglial Activation and Differentiation via the Notch Signaling Pathway

Inflammatory responses contribute to the pathogenesis of various neurological diseases, and microglia plays an important role in the process. Activated microglia can differentiate into the pro-inflammatory, tissue-damaging M1 phenotype or the anti-inflammatory, tissue-repairing M2 phenotype. Regulating microglia differentiation, hence limiting a harmful response, might help improve the prognosis of inflammation-related nervous system diseases. The present study aimed 1. to observe the anti-inflammatory effect of lipoxin A4 (LXA4) on the inflammatory response associated to lipopolysaccharide (LPS)-induced microglia activation, 2. to clarify that LXA4 modulates the activation and differentiation of microglia induced by LPS stimulation, 3. to determine whether LXA4 regulates the activation and differentiation of microglia through the Notch signaling pathway, 4. to provide a foundation for the use of LXA4 for the treatment of inflammatory related neurological diseases. To construct a model of cellular inflammation, immortalized murine BV2 microglia cells were provided 200 ng/ml LPS. To measure the mRNA and protein levels of inflammatory factors (interleukin [IL]-1β, IL-10, and tumor necrosis factor [TNF]-α) and M1 and M2 microglia markers (inducible nitric oxide synthase [iNOS], cluster of differentiation [CD]32, arginase [Arg]1, and CD206), we performed quantitative reverse transcription polymerase chain reaction (qRT-PCR) and enzyme-linked immunosorbent assay (ELISA), immunofluorescence, or flow cytometry. To determine the mRNA and protein levels of Notch signaling components (Notch1, Hes1, and Hes5), we performed qRT-PCR and western blot. LXA4 inhibits the expression of Notch1 and Hes1 associated with M1 type microglial differentiation and decreases the M1 type microglia marker iNOS and related inflammatory factors IL-1β and TNF-α. Moreover, LXA4 upregulates the expression of the M2-associated Hes5, as well as the expression of the M2 microglia marker Arg1 and the associated inflammatory factor IL-10. These effects are blocked by the administration of the γ-secretase inhibitor DAPT, a specific blocker of the Notch signaling pathway. LXA4 inhibits the microglia activation induced by LPS and the differentiation into M1 type with pro-inflammatory effect, while promoting the differentiation to M2 type with anti-inflammatory effect. LXA4 downregulates the inflammatory mediators IL-1β, TNF-α, and iNOS, while upregulating the anti-inflammatory mediator IL-10, which acts through the Notch signaling pathway.

Lipoxin A4 receptor agonist BML-111 induces autophagy in alveolar macrophages and protects from acute lung injury by activating MAPK signaling

Background

Acute lung injury (ALI) is a life-threatening lung disease where alveolar macrophages (AMs) play a central role both in the early phase to initiate inflammatory responses and in the late phase to promote tissue repair. In this study, we examined whether BML-111, a lipoxin A4 receptor agonist, could alter the phenotypes of AM and thus present prophylactic benefits for ALI.

Methods

In vitro, isolated AMs were treated with lipopolysaccharide (LPS) to induce ALI. In response to BML-111 pre-treatment, apoptosis and autophagy of AMs were examined by flow cytometry, and by measuring biomarkers for each process. The potential involvement of MAPK1 and mTOR signaling pathway was analyzed. In vivo, an LPS-induced septic ALI model was established in rats and the preventative significance of BML-111 was assessed. On the cellular and molecular levels, the pro-inflammatory cytokines TNF-α and IL-6 from bronchoalveolar lavage were measured by ELISA, and the autophagy in AMs examined using Western blot.

Results

BML-111 inhibited apoptosis and induced autophagy of AMs in response to ALI inducer, LPS. The enhancement of autophagy was mediated through the suppression of MAPK1 and MAPK8 signaling, but independent of mTOR signaling. In vivo, BML-111 pre-treatment significantly alleviated LPS-induced ALI, which was associated with the reduction of apoptosis, the dampened production of pro-inflammatory cytokines in the lung tissue, as well as the increase of autophagy of AMs.

Conclusions

This study reveals the prophylactic significance of BML-111 in ALI and the underlying mechanism: by targeting the MAPK signaling but not mTOR pathway, BML-111 stimulates autophagy in AMs, attenuates the LPS-induced cell apoptosis, and promotes the resolution of ALI.

Zileuton suppresses cholangiocarcinoma cell proliferation and migration through inhibition of the Akt signaling pathway

Background

Inflammatory lipid mediators play an important role in several cancer types. Leukotrienes (LTs), pro-inflammatory lipid mediators, are involved in chronic inflammation and cancer progression. They are derived from arachidonic acid by 5-lipoxygenase (5-LOX) activity. On the other hand, 15-lipoxygenase (15-LOX-1) converts LTs into lipoxins (LXs), pro-resolving lipid mediators. LXs are involved in the attenuation of inflammation and cancer development.

Purpose

We aimed to investigate the lipid mediator pathways, especially the LTs and LXs pathways, by studying 5-LOX and 15-LOX-1 expression in human cholangiocarcinoma (CCA) tissue. We also investigated the efficiency of zileuton (5-LOX inhibitor) treatment and BML-111 (LXA4 analog) addition on CCA cell lines properties.

Patients and methods

The expression of 5-LOX and 15-LOX-1 in fifty human cholangiocarcinoma (CCA) tissue was analyzed using immunohistochemical staining. In addition, the effect of zileuton and BML-111 on CCA cell growth and migration was demonstrated using a cell viability assay and wound-healing assay, respectively. Furthermore, the molecular mechanism by which zileuton inhibits CCA cell migration was revealed using immunofluorescent staining and western blot analysis, respectively.

Results

We demonstrate that the upregulation of 5-LOX is significantly correlated with CCA recurrent status. A positive 15-LOX-1 signal was significantly associated with a longer survival time in CCA patients. We found that co-expression of 5-LOX and 15-LOX-1 resulted in a relatively good prognosis in CCA patients. In addition, zileuton could inhibit CCA cell migration as well as BML-111. Interestingly, zileuton treatment not only downregulated 5-LOX, but also upregulated 15-LOX-1, together with reversing the epithelial-mesenchymal transition to mesenchymal-epithelial transition phenotype as observed in EMT marker western blot.

Conclusion

These findings suggest that 5-LOX and 15-LOX-1 play a key role in CCA and may serve as targets for CCA therapy.

Aloperine inhibits proliferation, migration and invasion and induces apoptosis by blocking the Ras signaling pathway in human breast cancer cells

Aloperine (Alo), as a quinolizidine alkaloid extracted from S. alopecuroide, has the positive activities of anti-inflammatory, anti-allergenic, antitumor and anti-viral. However, the role and mechanism of Alo in breast cancer have not been studied yet. In the present study, Alo markedly inhibited the proliferation and suppressed the colony formation ability of the breast cancer cell lines MCF-7 and MDA-MB-231 in a dose-dependent manner by Cell Counting kit-8 and colony formation assays, respectively. In addition, the results of confocal microscopy analysis and flow cytometry detection revealed that Alo induced the apoptosis of MCF-7 and MDA-MB-231 cells, and western blotting indicated that Alo upregulated the protein levels of Bax, caspase-3 and caspase-9, and downregulated the expression of Bcl-2. Furthermore, the results of wound healing, Transwell migration and invasion assays demonstrated that Alo inhibited the migration and invasion of MCF-7 and MDA-MB-231 cells, and reduced the protein levels of matrix metalloproteinase (MMP)-2 and MMP-9. Alo also downregulated the protein expressions of Ras, phosphorylated (p)-Raf proto-oncogene, serine/threonine kinase 1 and p-extracellular signal-regulated kinase 1/2. Furthermore, ISIS 2503, a Ras inhibitor, inhibited colony formation, induced apoptosis, and suppressed the migration and invasion of MCF-7 and MDA-MB-231 cells. These effects were more marked in the presence of ISIS 2503 and Alo, when compared with those of either agent alone. In conclusion, the present study reported a novel use of Alo in inhibiting the proliferation, migration and invasion, and inducing the apoptosis of human breast cancer cells by blocking the Ras signaling pathway.

Lipoxin A4 and its analog suppress hepatocarcinoma cell epithelial-mesenchymal transition, migration and metastasis via regulating integrin-linked kinase axis

Epithelial-mesenchymal Transition (EMT) and migration play an important role in tumor progression, and lipoxin (LX), the 'stop signal' for inflammation, has been studied in basic research for its anti-inflammatory or inflammatory pro-resolving properties. Here, in the in vitro experiment, we showed that LXA₄ could inhibit the EMT and migration in phorbol myristate acetate (PMA) or activated conditioned medium (ACM)-stimulated Hep3B cells by downregulation of integrin-linked kinase (ILK), a pseudokinase in cytoplasm and these effects were via inhibiting the phosphorylation of Akt and GSK3β. Morover, LXA₄ could not affect the EMT and migration of PMA-stimulated Hep3B cells by knockdown of ILK. In the in vivo experiment, BML-111 (the analog of LXA₄) could inhibit the EMT and metastasis of hepatocarcinoma cells. We also demonstrated that ILK siRNA inhibited phosphorylation of downstream signaling targets Akt and GSK3β, decreased expression of MMP-2 and MMP-9. These results showed that LXA₄ could be a possible candidate for liver cancer therapy, and blocking ILK axis would be an effective drug target.

Differential action of polyunsaturated fatty acids and eicosanoids on bleomycin-induced cytotoxicity to neuroblastoma cells and lymphocytes

INTRODUCTION

This study was conducted to examine whether bleomycin-induced growth inhibitory action on human neuroblastoma cells (IMR-32) is influenced by anti-inflammatory metabolites of polyunsaturated fatty acids (PUFAs): lipoxin A4 (LXA4), resolvin D1 and protectin D1 in vitro.

MATERIAL AND METHODS

The in vitro study was conducted using monolayer cultures of exponentially growing IMR-32 cells. The effects of various PUFAs and eicosanoids and anti-inflammatory metabolites of PUFAs such as lipoxin A4 (LXA4), resolvin D1 and protectin D1 on the growth of IMR-32 cells and human lymphocytes in vitro were investigated. The potential of PUFAs, eicosanoids and LXA4, resolvin D1 and protectin D1 to modify the growth inhibitory effects of bleomycin was also studied in IMR-32 cells and human lymphocytes.

RESULTS

PUFAs inhibited the growth of IMR-32 cells (EPA > DHA = AA > GLA = ALA > DGLA = LA) significantly (p < 0.001) while prostaglandins were found to be not effective. Bleomycin-induced growth inhibitory action on IMR-32 cells was augmented by PUFAs and its metabolites (p < 0.05). PUFAs and LXA4 did not inhibit the growth of human lymphocytes and bleomycin-induced growth inhibitory action was also not enhanced by these bioactive lipids.

CONCLUSIONS

Bioactive lipids have differential action on normal human lymphocytes and tumor cells in vitro. The apparent lack of effect of PUFAs in combination with bleomycin on the growth of human lymphocytes in comparison to their growth inhibitory action on IMR-32 cells suggests that PUFAs can be used in combination with bleomycin to target tumor cells with little concern over this combination's effect on the growth of human lymphocytes. Further studies are warranted to evaluate these differential effects under in vivo conditions.

Lipoxin A4 reverses mesenchymal phenotypes to attenuate invasion and metastasis via the inhibition of autocrine TGF-β1 signaling in pancreatic cancer

Background

Pancreatic cancer is a lethal disease in part because of its potential for aggressive invasion and metastasis. Lipoxin A4 (LXA4) is one of the metabolites that is derived from arachidonic acid and that is catalyzed by 15-lipoxygenase (15-LOX), and it has recently been reported to exhibit anti-cancer effects. However, the role of LXA4 in pancreatic cancer remains to be elucidated.

Methods

Pancreatic cell lines were treated with vehicle or LXA4, and the invasive capacity was then assessed by Transwell assays. The expression of epithelial and mesenchymal markers was determined by western blotting and immunofluorescence. Anti-TGF-β1 neutralizing antibody and exogenous recombinant human TGF-β1 (rhTGF-β1) were used to study the effect of LXA4 on the TGF-β signaling. A liver metastasis model was applied to investigate the effect of LXA4 in vivo. The correlation between the Lipoxin effect score (LES) and the clinical-pathological features of pancreatic cancer was also analyzed.

Results

We found that in patients with pancreatic cancer, low LES was correlated with aggressive metastatic potential. The LXA4 activity, which was mediated by the LXA4 receptor FPRL1, could significantly suppress invasion capacity and mesenchymal phenotypes. The expression and autocrine signaling pathway activity of TGF-β1 were also downregulated by LXA4. In the liver metastasis model in nude mice, the stable analog of LXA4, BML-111, could inhibit the metastasis of pancreatic cancer cells.

Conclusion

Our results demonstrated that LXA4 could reverse mesenchymal phenotypes, which attenuated invasion and metastasis via the inhibition of autocrine TGF-β1 signaling in pancreatic cancer, which may provide a new strategy to prevent the metastasis of pancreatic cancer.

Erythropoietin promoted the proliferation of hepatocellular carcinoma through hypoxia induced translocation of its specific receptor

Background

Erythropoietin (EPO) is a hypoxia-inducible stimulator of erythropoiesis. Besides its traditional application in anemia therapy, it offers an effective treatment in the cancer patients, especially those who receive chemotherapy. Several reports indicated that it could promote the tumor cell proliferation through its specific receptor (EPOR). Unfortunately, the role of EPO/EPOR in hepatocellular carcinoma (HCC) progressing is still uncertain.

Methods

Protein in tumor tissue from HCC patients or H22 tumor-bearing mice was detected with immunohistochemistry. Cells were cultured under 1% oxygen to establish hypoxia. RT-PCR and western blotting were used to measure mRNA and protein of EPO/EPOR, respectively. MTT, flow cytometry and PCNA staining were used to detect cell proliferation. Immunofluorescence staining was applied to study the expression and location of cellular EPOR. The EPOR binding studies were performed with ¹²⁵I-EPO radiolabeling assay.

Results

EPO and EPOR protein were up-regulated in HCC tissue of patients and H22-bearing mice. These were positively correlated with hypoxia-inducible factor -1 α and ki-67. Hypoxia up-regulated the expression of EPO and EPOR in HepG2 cells. It also induced the proliferation and increased the percentage of divided cells after 24, 48 and 72 h treatment. These were inhibited in cells pre-treated with 0.5 μg/mL soluble-EPOR. Immunofluorescence staining presented that EPOR was obviously translocated from nucleus to cytoplasm and membrane under hypoxia. EPOR binding activity was also increased after exposure to hypoxia. Recombinant human erythropoietin obviously elevated cell proliferation rate and the percentage of divided under hypoxia but not normoxia, which were also inhibited by soluble-EPOR.

Conclusions

Our result indicated for the first time that EPO promoted the proliferation of HCC cells through hypoxia induced translocation of it specific receptor.

Trial registration TJC20141113, retrospectively registered

Prolyl hydroxylase domain protein 3 and asparaginyl hydroxylase factor inhibiting HIF-1 levels are predictive of tumoral behavior and prognosis in hepatocellular carcinoma

Hypoxia-inducible factors (HIFs) are key regulators in oxygen homeostasis. Their stabilization and activity are regulated by prolyl hydroxylase domain (PHD)-1, -2, -3 and factor inhibiting HIF (FIH). This study investigated the relation between these oxygen sensors and the clinical behaviors and prognosis of hepatocellular carcinoma (HCC). Tissue microarray and RT-PCR analysis of tumor tissues and adjacent non-tumor liver tissues revealed that mRNA and protein levels of both PHD3 and FIH were lower within tumors. The lower expression of PHD3 in tumor was associated with larger tumor size, incomplete tumor encapsulation, vascular invasion and higher Ki-67 LI (p < 0.05). The lower expression of FIH in tumor was associated with incomplete tumor encapsulation, vascular invasion, as well as higher TNM stage, BCLC stage, microvascular density and Ki-67 LI (p < 0.05). Patients with reduced expression of PHD3 or FIH had markedly shorter disease-free survival (DFS), lower overall survival (OS), or higher recurrence (p < 0.05), especially early recurrence. Patients with simultaneously reduced expression of PHD3 and FIH exhibited the least chance of forming tumor encapsulation, highest TNM stage (p < 0.0083), lowest OS and highest recurrence rate (p < 0.05). Multivariate analysis indicated that a lower expression of FIH independently predicted a poor prognosis in HCC. These findings indicate that downregulation of PHD3 and FIH in HCC is associated with more aggressive tumor behavior and a poor prognosis. PHD3 and FIH may be potential therapeutic targets for HCC treatment.

BML-111 equilibrated ACE-AngII-AT1R and ACE2-Ang-(1-7)-Mas axis to protect hepatic fibrosis in rats

BACKGROUND

It was recently reported Lipoxins (LXs) had protective effects on fibrous diseases, and renin-angiotensin-aldosterone system (RAAS) had played vital and bidirectional roles in hepatic fibrosis. In this paper, a hepatic fibrosis model, induced by carbon tetrachloride (CCL₄) in rats, was used to observe the relations between RAAS and LXs, as well as to further explore the alternative anti-fibrosis mechanisms of LXs.

METHODS

The model was evaluated by morphological observations and biochemical assays. The activities and contents of angiotensin converting enzyme (ACE) and angiotensin converting enzyme 2 (ACE2) were examined through assay kits and ELISA. The expression levels of angiotensinII (AngII), Angiotensin II type 1 receptor (AT1R), angiotensin-(1-7) (Ang-1-7), and Mas were all measured using real time PCR, ELISA, and Western blot.

RESULTS

The model was established successfully and BML-111 significantly ameliorated CCL₄-induced hepatic fibrosis, including reduction inflammation injury, decrease extracellular matrix deposition, and improvement hepatic functions. Furthermore, BML-111 could obviously decrease not only the activities of ACE but also the expression levels of ACE, AngII,and AT1R, which were induced by CCL₄. On the other hand, BML-111 could markedly increase the activities of ACE2, besides the expression levels of ACE2, Ang-(1-7) and Mas. More importantly, BOC-2, a lipoxin A₄ receptor blocker, could reverse all these phenomena.

CONCLUSIONS

Equilibrating ACE-AngII-AT1R axis and ACE2-Ang-(1-7)-Mas axis mediated the protective effect of BML-111 on hepatic fibrosis in rats.

Plasma lipoxin A4 and resolvin D1 are not associated with reduced adenoma risk in a randomized trial of aspirin to prevent colon adenomas

Inflammation plays a major role in colon carcinogenesis. Endogenously produced specialized proresolving lipid mediators (SPMs) play a central role in inflammation and tissue homeostasis, and have been implicated in carcinogenesis. We studied the associations of plasma levels of two SPMs [lipoxin A₄ (LXA₄ ) and resolvin D1(RvD1)] with risk for recurrent adenoma. In this pilot study, we used data and biosamples from an adenoma chemoprevention study investigating the effects of aspirin and/or folic acid on the occurrence of colorectal adenomas. In the parent study, 1121 participants with a recent adenoma were randomized to study agents to be taken until the next surveillance colonoscopy about 3 years later. In this pilot study, LXA₄ and RvD1 from samples taken near the end of study treatment were measured in a randomly selected sub-set of 200 participants. Commercially available ELISA kits to assay the analytes were validated using a metabololipidomic LC-MS/MS assay. Poisson regression with a robust error variance was used to calculate risk ratios and 95% confidence intervals. Plasma LXA₄ and RvD1 were not associated with the risk of adenoma occurrence. LXA₄ at the end of study follow-up was 32% (P = 0.01) proportionately higher in women compared to men. A similar non-significant trend toward higher levels among women was observed for RvD1. Our preliminary findings provided no evidence that plasma LXA₄ or RvD1 are associated with reduced risk of colorectal adenoma occurrence, but suggest LXA₄ may differ among men and women. Future studies focusing on SPM's local effects and levels in the colon are needed.

Erythropoietin promoted the proliferation of hepatocellular carcinoma through hypoxia induced translocation of its specific receptor

BACKGROUND

Erythropoietin (EPO) is a hypoxia-inducible stimulator of erythropoiesis. Besides its traditional application in anemia therapy, it offers an effective treatment in the cancer patients, especially those who receive chemotherapy. Several reports indicated that it could promote the tumor cell proliferation through its specific receptor (EPOR). Unfortunately, the role of EPO/EPOR in hepatocellular carcinoma (HCC) progressing is still uncertain.

METHODS

Protein in tumor tissue from HCC patients or H22 tumor-bearing mice was detected with immunohistochemistry. Cells were cultured under 1% oxygen to establish hypoxia. RT-PCR and western blotting were used to measure mRNA and protein of EPO/EPOR, respectively. MTT, flow cytometry and PCNA staining were used to detect cell proliferation. Immunofluorescence staining was applied to study the expression and location of cellular EPOR. The EPOR binding studies were performed with ¹²⁵I-EPO radiolabeling assay.

RESULTS

EPO and EPOR protein were up-regulated in HCC tissue of patients and H22-bearing mice. These were positively correlated with hypoxia-inducible factor -1 α and ki-67. Hypoxia up-regulated the expression of EPO and EPOR in HepG2 cells. It also induced the proliferation and increased the percentage of divided cells after 24, 48 and 72 h treatment. These were inhibited in cells pre-treated with 0.5 μg/mL soluble-EPOR. Immunofluorescence staining presented that EPOR was obviously translocated from nucleus to cytoplasm and membrane under hypoxia. EPOR binding activity was also increased after exposure to hypoxia. Recombinant human erythropoietin obviously elevated cell proliferation rate and the percentage of divided under hypoxia but not normoxia, which were also inhibited by soluble-EPOR.

CONCLUSIONS

Our result indicated for the first time that EPO promoted the proliferation of HCC cells through hypoxia induced translocation of it specific receptor. Trial registration TJC20141113, retrospectively registered.

Diabetic macular edema, retinopathy and age-related macular degeneration as inflammatory conditions

Diabetic macular edema (DME) and diabetic retinopathy (DR) are complications affecting about 25% of all patients with long-standing type 1 and type 2 diabetes mellitus and are a major cause of significant decrease in vision and quality of life. Age-related macular degeneration (AMD) is not uncommon, and diabetes mellitus affects the incidence and progression of AMD through altering hemodynamics, increasing oxidative stress, accumulating advanced glycation end products, etc. Recent studies suggest that DME, DR and AMD are inflammatory conditions characterized by a breakdown of the blood-retinal barrier, inflammatory processes and an increase in vascular permeability. Key factors that seem to have a dominant role in DME, DR and AMD are angiotensin II, prostaglandins and the vascular endothelial growth factor and a deficiency of anti-inflammatory bioactive lipids. The imbalance between pro- and anti-inflammatory eicosanoids and enhanced production of pro-angiogenic factors may initiate the onset and progression of DME, DR and AMD. This implies that bioactive lipids that possess anti-inflammatory actions and suppress the production of angiogenic factors could be employed in the prevention and management of DME, DR and AMD.

BML-111 Protected LPS/D-GalN-Induced Acute Liver Injury in Rats

Lipoxins (LXs) display unique pro-resolving and anti-inflammatory functions in a variety of inflammatory conditions. The present study was undertaken to investigate the effects of BML-111 (5(S),6(R),7-trihydroxyheptanoic acid methyl ester), the agonist of lipoxin A₄ receptor, in a model of Lipopolysaccharides (LPS) and d-Galactosamine (d-GalN) induced acute liver injury, and to explore the mechanisms. Histopathological analyses were carried out to quantify liver injury degree. The activities of myeloperoxidase (MPO) were examined to evaluate the levels of neutrophil infiltration. The activities of aspartate aminotransferase (AST) and alanine aminotransferase (ALT) in serum were detected to evaluate the functions of the liver. The amounts of tumor necrosis factor-α (TNF-α), interleukin-10 (IL-10), and interleukin-1β (IL-1β) were measured using enzyme-linked immunosorbent assay (ELISA), and the expression levels of transforming growth factor-β1(TGF-β1) and cyclooxygenase-2 (COX-2) were examined using Western blotting. The antioxidant capacity, the activities of inducible nitric oxide synthase (iNOS), the contents of malondialdehyde (MDA) and nitric oxide (NO) were analyzed with the kits via biochemical analysis. We established the model of acute liver injury with lipopolysaccharide and d-Galactosamine (LPS/d-GalN): (1) histopathological results and MPO activities, with the activities of AST and ALT in serum, consistently demonstrated LPS and d-GalN challenge could cause severe liver damage, but BML-111 could prevent pathological changes, inhibit neutrophil infiltration, and improve the hepatic function; (2) LPS/d-GalN increased TNF-α, IL-1β, COX-2, and IL-10, while decreasing TGF-β1. However, BML-111 could repress LPS/d-GalN -induced TNF-α, IL-1β and COX-2, meanwhile increasing the expression levels of TGF-β1 and IL-10; (3) LPS/d-GalN inhibited the activities of superoxide dismutase (SOD), catalase (CAT), total antioxidant capacity (T-AOC), and hydroxyl radical-scavenging ability, simultaneously increasing the levels of MDA and NO, so also the activity of iNOS. Otherwise, BML-111 could reverse all the phenomena. In a word, BML-111 played a protective role in acute liver injury induced by LPS and d-GalN in rats, through improving antioxidant capacity and regulating the balance of inflammatory cytokines.

Walker 256 Tumor Growth Suppression by Crotoxin Involves Formyl Peptide Receptors and Lipoxin A₄

We investigated the effects of Crotoxin (CTX), the main toxin of South American rattlesnake (Crotalus durissus terrificus) venom, on Walker 256 tumor growth, the pain symptoms associated (hyperalgesia and allodynia), and participation of endogenous lipoxin A₄. Treatment with CTX (s.c.), daily, for 5 days reduced tumor growth at the 5th day after injection of Walker 256 carcinoma cells into the plantar surface of adult rat hind paw. This observation was associated with inhibition of new blood vessel formation and decrease in blood vessel diameter. The treatment with CTX raised plasma concentrations of lipoxin A₄ and its natural analogue 15-epi-LXA₄, an effect mediated by formyl peptide receptors (FPRs). In fact, the treatment with Boc-2, an inhibitor of FPRs, abolished the increase in plasma levels of these mediators triggered by CTX. The blockage of these receptors also abolished the inhibitory action of CTX on tumor growth and blood vessel formation and the decrease in blood vessel diameter. Together, the results herein presented demonstrate that CTX increases plasma concentrations of lipoxin A₄ and 15-epi-LXA₄, which might inhibit both tumor growth and formation of new vessels via FPRs.

Lipoxin A4 Attenuates Cell Invasion by Inhibiting ROS/ERK/MMP Pathway in Pancreatic Cancer

Lipoxin A₄ (LXA₄), an endogenous arachidonic acid metabolite, was previously considered an anti-inflammatory lipid mediator. But it also has the potential to inhibit cancer progression. To explore the therapeutic effect of LXA₄ in pancreatic cancer, we used Panc-1 cells to investigate the mechanism by which LXA₄ can attenuate pancreatic cancer cell invasion. Our data showed that LXA₄ significantly inhibited both cell invasion and the expression of matrix metalloproteinase- (MMP-) 9 and MMP-2. Further experiments implied that LXA₄ decreased the levels of intracellular reactive oxygen species (ROS) and the activity of the extracellular signal regulated kinases (ERK) pathway to achieve similar outcome to ROS scavenger N-acetyl-l-cysteine (NAC). However, a decreased level of intracellular ROS was not observed in cells treated with the specific ERK pathway inhibitor FR180204. The blocking of either intracellular ROS or ERK pathway caused the downregulation of MMP-9 and MMP-2 expression. Furthermore, tests revealed that LXA₄ inhibited MMP-9 and MMP-2 at the mRNA, protein, and functional levels. Finally, LXA₄ dramatically limited the invasion of CoCl₂-mimic hypoxic cells and abrogated intracellular ROS levels, ERK activity, and MMPs expression. These results suggest that LXA₄ attenuates cell invasion in pancreatic cancer by suppressing the ROS/ERK/MMPs pathway, which may be beneficial for preventing the invasion of pancreatic cancer.

Formyl peptide receptors at the interface of inflammation, angiogenesis and tumor growth

N-formyl peptide receptors (FPRs) belong to the family of pattern recognition receptors (PRRs) that regulate innate immune responses. Three FPRs have been identified in humans: FPR1-FPR3. FPR expression was initially described in immune cells and subsequently in non-hematopoietic cells and certain tissues. Besides their involvement in inflammatory disorders, FPRs have been implicated in the regulation of tissue repair and angiogenesis. Angiogenesis is not only a key component of pathogen defence during acute infection and of chronic inflammatory disorders, but also plays a critical role in wound healing and tissue regeneration. Moreover, pathologic uncontrolled angiogenesis is central for tumour growth, progression, and the formation of metastases. In this review, we summarise the evidence for a central role of FPRs at the intersection between inflammation, physiologic angiogenesis and pathologic neovascularisation linked to cancer. These findings provide insights into the potential clinical relevance of new treatment regimens involving FPR modulation.

Lipid mediator lipoxin A4 inhibits tumor growth by targeting IL-10-producing regulatory B (Breg) cells

Lipoxin A4 (LXA4), an arachidonic acid-derived anti-inflammatory lipid mediator, shows anti-tumor potential by regulating tumor immune microenvironments. However, the underlying molecular and cellular basis of this function remains unclear. IL-10-producing B (Breg) cells display tumor-promoting effects by negatively regulating anti-tumor immunity. Here we show that LXA4 inhibits tumor growth by suppressing the generation of Breg cells in tumor-bearing mice. The administration of LXA4 inhibited the induction of Breg cells. Breg cell deficiency, in turn, resulted in LXA4 losing its anti-tumor properties. Intriguingly, regulatory T (Treg) cells also had a role in this process. Targeting Breg cells by LXA4 decreased the number of Treg cells in draining lymph nodes and tumor tissues as well as enhanced cytotoxic T cell activities. In addition, we further demonstrated that LXA4 inhibited Breg cells through its dephosphorylating STAT3 and ERK. These findings unveil a new anti-tumor mechanism underlying LXA4 targeting Breg cells with potential clinical applications.

Bufothionine induced the mitochondria-mediated apoptosis in H22 liver tumor and acute liver injury

Background

Bufothionine is an alkaloid in Cinobufacini (Huachansu). This study aims to investigate the effects of bufothionine on liver tumors and acute liver injury.

Methods

In the hepatoprotective experiment, fifty rats were randomly divided into five groups (n = 10): normal saline group, model group, compound glycyrrhizin injection (9.14 mL/kg); cinobufacini injection (3.42 mL/kg) (InjA) and bufothionine (9.77 mL/kg) (BufoA) group. Liver weight indices were recorded to judge the degree of liver swelling, hematoxylin and eosin (H&E) staining of liver tissues was carried out to observe liver histological morphology injury and biochemical indicators including aspartate aminotransferase (AST); alanine aminotransferase (ALT); alkaline phosphatase (ALP); and total bilirubin (TBIL) were determined by modular auto-analyzer. In anti-tumor experiment, H₂₂-tumor-bearing mice were randomly divided into five groups (n = 10): normal saline group, model group, cinobufacini injection (InjB) (5.14 mL/kg), bufothionine (8.02 mL/kg) (BufoB) and 5-fluorouracil (5-Fu) (3.42 mL/kg). Tumors were picked out and determined with vernier calipers. Histological morphology of tumors was observed by H&E staining. In SMMC-7721 cells, expressions of proteins related to mitochondria-mediated apoptosis pathway including Bcl-2, Bax, caspase-3, caspase-9, cyto-c, Bid, and p53 were analyzed by western blotting at low, medium, high concentrations of bufothione (3.62 μg/mL, 18.12 μg/mL,90.62 μg/mL).

Results

Butothionine relieved CCl₄-induced liver morphology, decreased the level of ALT (P =2.46 × 10^-2) and expressed tendency to decrease other biochemical markers including AST, ALP and TBIL. Butothionine could also promote necrosis of tumor tissue in H₂₂-tumor-bearing mice and restrained tumor growth with 65.16% inhibition rate. Its mechanism might relate to up-regulation of p53 (at low, mediate and high concentration, corresponding P values were 0.142, 0.0257, 0.0162), caspase-3 (P = 0.246, 0.0267 and 0.0236), cyto-c (P = 0.276, 0.0343 and 0.0429), Bid (P = 0.0125, 0.0395 and 0.0132) and Bax (P = 0.563, 0.0492 and 0.0357) in a dose-dependent manner, down-regulation of Bcl-2 expression (P = 0.0232, 0.0178 and 0.0464), but had no significant effects on caspase-9 (P = 0.253, 0.147 and 0.287).

Conclusion

Bufothionine induced the proteins for the mitochondria-mediated apoptosis that inhibits liver tumors and protects the liver against acute injury.

Effect of polyunsaturated fatty acids and their metabolites on bleomycin-induced cytotoxic action on human neuroblastoma cells in vitro

In the present study, we noted that bleomycin induced growth inhibitory action was augmented by all the polyunsaturated fatty acids (PUFAs) tested on human neuroblastoma IMR-32 (0.5 × 10(4) cells/100 µl of IMR) cells (EPA > DHA > ALA = GLA = AA > DGLA = LA: ∼ 60, 40, 30, 10-20% respectively) at the maximum doses used. Of all the prostaglandins (PGE1, PGE2, PGF2α, and PGI2) and leukotrienes (LTD4 and LTE4) tested; PGE1, PGE2 and LTD4 inhibited the growth of IMR-32 cells to a significant degree at the highest doses used. Lipoxin A4 (LXA4), 19,20-dihydroxydocosapentaenoate (19, 20 DiHDPA) and 10(S),17(S)-dihydroxy-4Z,7Z,11E,13Z,15E,19Z-docosahexaenoic acid (protectin: 10(S),17(S)DiHDoHE), metabolites of DHA, significantly inhibited the growth of IMR-32 cells. Pre-treatment with AA, GLA, DGLA and EPA and simultaneous treatment with all PUFAs used in the study augmented growth inhibitory action of bleomycin. Surprisingly, both indomethacin and nordihydroguaiaretic acid (NDGA) at 60 and 20 µg/ml respectively enhanced the growth of IMR-32 cells even in the presence of bleomycin. AA enhanced oxidant stress in IMR-32 cells as evidenced by an increase in lipid peroxides, superoxide dismutase levels and glutathione peroxidase activity. These results suggest that PUFAs suppress growth of human neuroblastoma cells, augment growth inhibitory action of bleomycin by enhancing formation of lipid peroxides and altering the status of anti-oxidants and, in all probability, increase the formation of lipoxins, resolvins and protectins from their respective precursors that possess growth inhibitory actions.

The specialized proresolving mediator 17-HDHA enhances the antibody-mediated immune response against influenza virus: a new class of adjuvant?

Influenza viruses remain a critical global health concern. More efficacious vaccines are needed to protect against influenza virus, yet few adjuvants are approved for routine use. Specialized proresolving mediators (SPMs) are powerful endogenous bioactive regulators of inflammation, with great clinical translational properties. In this study, we investigated the ability of the SPM 17-HDHA to enhance the adaptive immune response using an OVA immunization model and a preclinical influenza vaccination mouse model. Our findings revealed that mice immunized with OVA plus 17-HDHA or with H1N1-derived HA protein plus 17-HDHA increased Ag-specific Ab titers. 17-HDHA increased the number of Ab-secreting cells in vitro and the number of HA-specific Ab-secreting cells present in the bone marrow. Importantly, the 17-HDHA-mediated increased Ab production was more protective against live pH1N1 influenza infection in mice. To our knowledge, this is the first report on the biological effects of ω-3-derived SPMs on the humoral immune response. These findings illustrate a previously unknown biological link between proresolution signals and the adaptive immune system. Furthermore, this work has important implications for the understanding of B cell biology, as well as the development of new potential vaccine adjuvants.