14,15-EET induces the infiltration and tumor-promoting function of neutrophils to trigger the growth of minimal dormant metastases

Arachidonic acid metabolism regulates the development of retinopathy of prematurity among preterm infants

Extremely preterm infants are at risk of developing retinopathy of prematurity (ROP), characterized by neovascularization and neuroinflammation leading to blindness. Polyunsaturated fatty acid (PUFA) supplementation is recommended in preterm infants to lower the risk of ROP, however, with no significant improvement in visual acuity. Reasonably, this could be as a result of the non-consideration of PUFA metabolizing enzymes. We hypothesize that abnormal metabolism of the arachidonic acid (AA) pathway may contribute to severe stages of ROP. The present study investigated the AA-metabolizing enzymes in ROP pathogenesis by a targeted gene expression analysis of blood (severe ROP = 70, No/Mild = 56), placenta (preterm placenta = 6, full term placenta = 3), and human primary retinal cell cultures and further confirmed at the protein level by performing IHC in sections of ROP retina. The lipid metabolites were identified by LC-MS in the vitreous humor (VH; severe ROP = 15, control = 15). Prostaglandins D2 (p = 0.02), leukotrienes B5 (p = 0.0001), 11,12-epoxyeicosatrienoic acid (p = 0.01), and lipid-metabolizing enzymes of the AA pathway such as CYP1B1, CYP2C8, COX2, and ALOX15 were significantly upregulated while EPHX2 was significantly (0.04) downregulated in ROP cases. Genes involved in hypoxic stress, angiogenesis, and apoptosis showed increased expression in ROP. An increase in the metabolic intermediates generated from the AA metabolism pathway further confirmed the role of these enzymes in ROP, while metabolites for EPHX2 activity were low in abundance. Inflammatory lipid intermediates were higher compared to anti-inflammatory lipids in VH and showed an association with enzyme activity. Both the placenta of preterm infants who developed ROP and hypoxic retinal cultures showed a reduced expression of EPHX2. These findings suggested a strong involvement of EPHX2 in regulating retinal neovascularization and inflammation. The study results underscore the role of arachidonic acid metabolism in the development of ROP and as a potential target for preventing vision loss among preterm-born infants.

Neutrophils as potential therapeutic targets for breast cancer

Breast cancer (BC) remains the foremost cause of cancer mortality globally, with neutrophils playing a critical role in its pathogenesis. As an essential tumor microenvironment (TME) component, neutrophils are emerging as pivotal factors in BC progression. Growing evidence has proved that neutrophils play a Janus- role in BC by polarizing into the anti-tumor (N1) or pro-tumor (N2) phenotype. Clinical trials are evaluating neutrophil-targeted therapies, including Reparixin (NCT02370238) and Tigatuzumab (NCT01307891); however, their clinical efficacy remains suboptimal. This review summarizes the evidence regarding the close relationship between neutrophils and BC, emphasizing the critical roles of neutrophils in regulating metabolic and immune pathways. Additionally, we summarize the existing therapeutic approaches that target neutrophils, highlighting the challenges, and affirming the rationale for continuing to explore neutrophils as a viable therapeutic target in BC management.

Cytochrome P450 oxidase 2J inhibition suppresses choroidal neovascularization in mice

INTRODUCTION

Choroidal neovascularization (CNV) in age-related macular degeneration (AMD) leads to blindness. It has been widely reported that increased intake of ω-3 long-chain polyunsaturated fatty acids (LCPUFA) diets reduce CNV. Of the three major pathways metabolizing ω-3 (and ω-6 LCPUFA), the cyclooxygenase and lipoxygenase pathways generally produce pro-angiogenic metabolites from ω-6 LCPUFA and anti-angiogenic ones from ω-3 LCPUFA. Howevehr, cytochrome P450 oxidase (CPY) 2C produces pro-angiogenic metabolites from both ω-6 and ω-3 LCPUFA. The effects of CYP2J2 products on ocular neovascularization are still unknown. Understanding how each metabolic pathway affects the protective effect of ω-3 LCPUFA on retinal neovascularization may lead to therapeutic interventions.

OBJECTIVES

To investigate the effects of LCPUFA metabolites through CYP2J2 pathway and CYP2J2 regulation on CNV both in vivo and ex vivo.

METHODS

The impact of CYP2J2 overexpression and inhibition on neovascularization in the laser-induced CNV mouse model was assessed. The plasma levels of CYP2J2 metabolites were measured by liquid chromatography and tandem mass spectroscopy. The choroidal explant sprouting assay was used to investigate the effects of CYP2J2 inhibition and specific LCPUFA CYP2J2 metabolites on angiogenesis ex vivo.

RESULTS

CNV was exacerbated in Tie2-Cre CYP2J2-overexpressing mice and was associated with increased levels of plasma docosahexaenoic acids. Inhibiting CYP2J2 activity with flunarizine decreased CNV in both ω-6 and ω-3 LCPUFA-fed wild-type mice. In Tie2-Cre CYP2J2-overexpressing mice, flunarizine suppressed CNV by 33 % and 36 % in ω-6, ω-3 LCPUFA diets, respectively, and reduced plasma levels of CYP2J2 metabolites. The pro-angiogenic role of CYP2J2 was corroborated in the choroidal explant sprouting assay. Flunarizine attenuated ex vivo choroidal sprouting, and 19,20-EDP, a ω-3 LCPUFA CYP2J2 metabolite, increased sprouting. The combined inhibition of CYP2J2 with flunarizine and CYP2C8 with montelukast further enhanced CNV suppression via tumor necrosis factor-α suppression.

CONCLUSIONS

CYP2J2 inhibition augmented the inhibitory effect of ω-3 LCPUFA on CNV. Flunarizine suppressed pathological choroidal angiogenesis, and co-treatment with montelukast inhibiting CYP2C8 further enhanced the effect. CYP2 inhibition might be a viable approach to suppress CNV in AMD.

Neutrophils as an emerging therapeutic target and tool for cancer therapy

Activation of neutrophils is necessary for the protection of the host against microbial infection. This property can be used as mode of therapy for cancer treatment. Neutrophils have conflicting dual functions in cancer as either a tumor promoter or inhibitor. Neutrophil-based drug delivery has achieved increased attention in pre-clinical models. This review addresses in detail the different neutrophil constituents, the conflicting function of neutrophils and activation of the neutrophil as an important target of therapy for cancer treatment, and use of neutrophils or neutrophil membrane-derived vesicles as vehicles for drug delivery and targeting.

Cytochrome 4Z1 Expression is Associated with Unfavorable Survival in Triple-Negative Breast Cancers

Purpose

Triple-negative breast cancer (TNBC) is characterized by high mortality rate, and its clinical management is difficult and complex. Therefore, there is a need for extensive efforts aimed at accelerating the discovery of novel therapies for TNBC. CYP4Z1 has been implicated in the development of breast cancer. The current study aimed at characterizing the expression of CYP4Z1 on TNBC.

Materials and Methods

Using immunohistochemistry, CYP4Z1 expression was evaluated on 122 TNBC samples, four samples of breast cancers expressing ER, PR, and HER-2, and four samples of normal breast tissues. The association between the enzyme and various histopathological features and survival of patients were determined.

Results

CYP4Z1 was strongly expressed in 83.3% of various histopathological subtypes of TNBC, when compared to negative expression in normal breast tissues. Interestingly, there were marked variations in CYP4Z1 expression with respect to histopathology subtype, histological grade, histological stage and tumor diameter. There was a high incidence of CYP4Z1 expression in patients with advanced grades, late stages and larger tumor sizes. Importantly, CYP4Z1 expression was correlated with the survival of TNBC patients, but it was an independent determinant of the poor prognosis of TNBC (p< 0.05).

Conclusion

CYP4ZI may be a potential biomarker or target for evolving new CYP4Z1-targeted treatments.

Metabolism pathways of arachidonic acids: mechanisms and potential therapeutic targets

The arachidonic acid (AA) pathway plays a key role in cardiovascular biology, carcinogenesis, and many inflammatory diseases, such as asthma, arthritis, etc. Esterified AA on the inner surface of the cell membrane is hydrolyzed to its free form by phospholipase A2 (PLA2), which is in turn further metabolized by cyclooxygenases (COXs) and lipoxygenases (LOXs) and cytochrome P450 (CYP) enzymes to a spectrum of bioactive mediators that includes prostanoids, leukotrienes (LTs), epoxyeicosatrienoic acids (EETs), dihydroxyeicosatetraenoic acid (diHETEs), eicosatetraenoic acids (ETEs), and lipoxins (LXs). Many of the latter mediators are considered to be novel preventive and therapeutic targets for cardiovascular diseases (CVD), cancers, and inflammatory diseases. This review sets out to summarize the physiological and pathophysiological importance of the AA metabolizing pathways and outline the molecular mechanisms underlying the actions of AA related to its three main metabolic pathways in CVD and cancer progression will provide valuable insight for developing new therapeutic drugs for CVD and anti-cancer agents such as inhibitors of EETs or 2J2. Thus, we herein present a synopsis of AA metabolism in human health, cardiovascular and cancer biology, and the signaling pathways involved in these processes. To explore the role of the AA metabolism and potential therapies, we also introduce the current newly clinical studies targeting AA metabolisms in the different disease conditions.

Neutrophils: Orchestrators of the Malignant Phenotype

Neutrophils are the first leukocytes recruited to sites of inflammation, where they execute anti-microbial functions to eliminate infectious agents. These functions include phagocytosis, release of reactive oxygen species and the formation of neutrophil extracellular traps via NETosis. Neutrophils are receiving increasing attention in the context of cancer, where these same neutrophil-associated functions are also important for modulating tumor growth and metastatic progression. Neutrophils are phenotypically heterogeneous and, depending on the context, exert anti- or pro-tumorigenic functions. Increasing evidence also suggests an important role of neutrophils and their involvement in promoting multiple steps of the metastatic cascade. The steps include: (1) local invasion and intravasation of cancer cells into circulation, (2) survival of cancer cells in the bloodstream and extravasation at a distant site, (3) early cancer cell seeding/survival, and (4) progressive growth of cancer cells to form macroscopic metastases. Although neutrophil functions designed to eliminate infectious agents can also eliminate tumor cells, their dysregulation can promote tumor growth and enable metastasis at multiple steps along the metastatic cascade. In this review, we will provide an overview of the current advances in neutrophil biology in the context of cancer. We also discuss the emerging field of immunometabolism, in which the rewiring of alternative metabolic pathways within neutrophils can impact their pro-tumorigenic/pro-metastatic functions.

Myeloid Cells in Metastasis

Metastatic disease is the leading cause of death in patients with solid cancers. The progression to metastasis is a multistep process that involves detachment of tumor cells from their constraining basement membrane at the primary site, migration and intravasation into the circulation, survival in the circulation, extravasation into the secondary organ, and survival and growth at the secondary site. During these steps, tumor and immune cells interact and influence each other both within the tumor microenvironment and systemically. In particular, myeloid cells such as monocytes, macrophages, neutrophils, and myeloid-derived suppressor cells (myeloid regulatory cells) have been shown to play important roles in the metastatic process. These interactions open new avenues for targeting cancer metastasis, especially given the increasing interest in development of cancer immunotherapies. In this review, we describe the currently reported pathways and mechanisms involved in myeloid cell enhancement of the metastatic cascade.

Complex interrelationships between nitro-alkene-dependent inhibition of soluble epoxide hydrolase, inflammation and tumor growth

Nitro-oleate (10-nitro-octadec-9-enoic acid), which inhibits soluble epoxide hydrolase (sEH) by covalently adducting to C521, increases the abundance of epoxyeicosatrienoic acids (EETs) that can be health promoting, for example by lowering blood pressure or their anti-inflammatory actions. However, perhaps consistent with their impact on angiogenesis, increases in EETs may exacerbate progression of some cancers. To assess this, Lewis lung carcinoma (LLc1) cells were exposed to oleate or nitro-oleate, with the latter inhibiting the hydrolase and increasing their proliferation and migration in vitro. The enhanced proliferation induced by nitro-oleate was EET-dependent, being attenuated by the ETT-receptor antagonist 14,15-EE-5(Z)-E. LLc1 cells were engineered to stably overexpress wild-type or C521S sEH, with the latter exhibiting resistance to nitro-oleate-dependent hydrolase inhibition and the associated stimulation of tumor growth in vitro or in vivo. Nitro-oleate also increased migration in endothelial cells isolated from wild-type (WT) mice, but not those from C521S sEH knock-in (KI) transgenic mice genetically modified to render the hydrolase electrophile-resistant. These observations were consistent with nitro-oleate promoting cancer progression, and so the impact of this electrophile was examined in vivo again, but this time comparing growth of LLc1 cells expressing constitutive levels of wild-type hydrolase when implanted into WT or KI mice. Nitro-oleate inhibited tumor sEH (P < 0.05), with a trend for elevated plasma 11(12)-EET/DHET and 8(9)EET/DHET (dihydroxyeicosatrienoic acid) ratios when administered to WT, but not KI, mice. Although in vitro studies with LLc1 cells supported a role for nitro-oleate in cancer cell proliferation, it failed to significantly stimulate tumor growth in WT mice implanted with the same LLc1 cells in vivo, perhaps due to its well-established anti-inflammatory actions. Indeed, pro-inflammatory cytokines were significantly down-regulated in nitro-oleate treated WT mice, potentially countering any impact of the concomitant inhibition of sEH.

Tumor Cell Dormancy: Threat or Opportunity in the Fight against Cancer

Tumor dormancy, a clinically undetectable state of cancer, makes a major contribution to the development of multidrug resistance (MDR), minimum residual disease (MRD), tumor outgrowth, cancer relapse, and metastasis. Despite its high incidence, the whole picture of dormancy-regulated molecular programs is far from clear. That is, it is unknown when and which dormant cells will resume proliferation causing late relapse, and which will remain asymptomatic and harmless to their hosts. Thus, identification of dormancy-related culprits and understanding their roles can help predict cancer prognosis and may increase the probability of timely therapeutic intervention for the desired outcome. Here, we provide a comprehensive review of the dormancy-dictated molecular mechanisms, including angiogenic switch, immune escape, cancer stem cells, extracellular matrix (ECM) remodeling, metabolic reprogramming, miRNAs, epigenetic modifications, and stress-induced p38 signaling pathways. Further, we analyze the possibility of leveraging these dormancy-related molecular cues to outmaneuver cancer and discuss the implications of such approaches in cancer treatment.

Angiogenesis and vascular stability in eicosanoids and cancer

Angiogenesis and inflammation are hallmarks of cancer. Arachidonic acid and other polyunsaturated fatty acids (PUFAs) are primarily metabolized by three distinct enzymatic systems initiated by cyclooxygenases, lipoxygenases, and cytochrome P450 enzymes (CYP) to generate bioactive eicosanoids, including prostanoids, leukotrienes, hydroxyeicosatetraenoic acids, and epoxyeicosatrienoic acids. As some of the PUFA metabolites playing essential roles in inflammatory processes, these pathways have been widely studied as therapeutic targets of inflammation. Because of their anti-inflammatory effects, these pathways were also proposed as anti-cancer targets. However, although the eicosanoids were linked to endothelial cell proliferation and angiogenesis almost two decades ago, it is only recently PUFA metabolites, especially those generated by CYP enzymes and the soluble epoxide hydrolase (sEH), have been recognized as important signaling mediators in physiological and pathological angiogenesis. Despite the fact that tumor growth and invasion are heavily dependent on inner-tumor angiogenesis and influenced by vascular stability, the role played by PUFA metabolites in tumor angiogenesis and vessel integrity has been largely overlooked. This review highlights current knowledge on the function of PUFA metabolites generated by the CYP/sEH pathway in angiogenesis and vascular stability as well as their potential involvement in cancer development.

Neutrophil Degranulation, Plasticity, and Cancer Metastasis

Neutrophils are the first responders to inflammation and infection. Recently, an elevated neutrophil-to-lymphocyte ratio has generally become a prognostic indicator of poor overall survival in cancer. Accordingly, heterogeneous ill-defined neutrophil-like populations have been increasingly recognized as important players in cancer development. In addition, neutrophil granule proteins released upon cell activation have been associated with tumor progression; this differential granule mobilization may allow neutrophils - and possibly associated cancer cells - to leave the bloodstream and enter inflamed/infected tissues. This review discusses and proposes how granule mobilization may facilitate neutrophil-mediated transport of cancer cells into different tissues as well as leading to different cellular phenotypes that underlie remarkable neutrophil plasticity. This concept might inform novel neutrophil-centered approaches to putative cancer therapies.

MicroRNA regulation of TRAIL mediated signaling in different cancers: Control of micro steering wheels during the journey from bench-top to the bedside

Large-scale sequencing methodologies have helped us identify numerous genomic alterations and we have started to scratch the surface of many new targets for treatment of cancer and the associated predictive biomarkers. TRAIL (TNF-related apoptosis-inducing ligand) is a highly appreciated anti-cancer molecule because of its ability to selectively target cancer cells. However, confluence of information suggests that cancer cells develop resistance against TRAIL-based therapeutics. It is being realized that overexpression of anti-apoptotic proteins and inactivation of pro-apoptotic proteins significantly impairs TRAIL triggered apoptosis, particularly in clinical settings. Re-balancing of pro-and anti-apoptotic proteins and upregulation of death receptors with functionally active extrinsic and intrinsic apoptotic pathways are necessary to sensitize cancer cells to TRAIL based therapeutics. microRNAs (miRNAs) are involved in regulation of myriad of molecular processes and characterized into oncogenic and tumor suppressor miRNAs. Accumulating data has identified miRNAs which positively or negatively regulate TRAIL mediated signaling in cancer cells, helping us understand different steps at which TRAIL-mediated apoptotic signaling can be targeted. Here, we assess the status of our understanding of the mechanisms related to miRNA regulation of TRAIL mediated signaling, as well as the existing gaps therein, and discuss the challenges and opportunities that will help us get closer to personalized medicine.

14, 15-EET induces breast cancer cell EMT and cisplatin resistance by up-regulating integrin αvβ3 and activating FAK/PI3K/AKT signaling

Background

14,15-epoxyeicosatrienoic acid (14,15-EET) is an important lipid signaling molecule involved in the regulation of tumor metastasis, however, the role and molecular mechanisms of 14,15-EET activity in breast cancer cell epithelial-mesenchymal transition (EMT) and drug resistance remain enigmatic.

Methods

The 14, 15-EET level in serum and in tumor or non-cancerous tissue from breast cancer patients was measured by ELISA. qRT-PCR and western blot analyses were used to examine expression of integrin αvβ3. The role of 14, 15-EET in breast cancer cell adhesion, invasion was explored by adhesion and Transwell assays. The role of 14, 15-EET in breast cancer cell cisplatin resistance in vitro was determined by MTT assay. Western blot was conducted to detect the protein expressions of EMT-related markers and FAK/PI3K/AKT signaling. Xenograft models in nude mice were established to explore the roles of 14, 15-EET in breast cancer cells EMT and cisplatin resistance in vivo.

Results

In the present study, we show that serum level of 14, 15-EET increases in breast cancer patients and 14, 15-EET level of tumor tissue is higher than that of non-cancerous tissue. Moreover, 14, 15-EET increases integrin αvβ3 expression, leading to FAK activation. 14, 15-EET induces breast cancer cell EMT via integrin αvβ3 and FAK/PI3K/AKT cascade activation in vitro. Furthermore, we find that 14, 15-EET induces breast cancer cells EMT and cisplatin resistance in vivo, αvβ3 integrin and the resulting FAK/PI3K/AKT signaling pathway are responsible for 14, 15-EET induced-breast cancer cells cisplatin resistance.

Conclusions

Our findings suggest that inhibition of 14, 15-EET or inactivation of integrin αvβ3/FAK/PI3K/AKT pathway could serve as a novel approach to reverse EMT and cisplatin resistance in breast cancer cells.

Role of the CYP3A4-mediated 11,12-epoxyeicosatrienoic acid pathway in the development of tamoxifen-resistant breast cancer

Epoxyeicosatrienoic acid (EET) production via cytochrome P450 (CYP) epoxygenases closely correlates with the progression of breast cancer. However, its role in the development of chemoresistant breast cancers has yet to be elucidated. Here, we found that CYP3A4 expression and its epoxy-product, 11,12-epoxyeicosatrienoic acid (11,12-EET) was enhanced in tamoxifen (TAM)-resistant MCF-7 (TAMR-MCF-7) breast cancer cells compared to control MCF-7 cells. Treatment of TAMR-MCF-7 cells with ketoconazole and azamulin (selective CYP3A4 inhibitors) or 14,15-epoxyeicosa-5(Z)-enoic acid (14,15-EEZE, an EET antagonist) inhibited cellular proliferation and recovered the sensitivity to 4-hydroxytamoxifen. Chick chorioallantoic membrane and trans-well migration analyses revealed that the enhanced angiogenic, tumorigenic, and migration intensities of TAMR-MCF-7 cells were also significantly suppressed by ketoconazole and 14,15-EEZE. We previously reported that Pin1, a peptidyl prolyl isomerase, is a crucial regulator for higher angiogenesis and epithelial-mesenchymal transition characteristics of TAMR-MCF-7 cells. EET inhibition suppressed E2F1-dependent Pin1 gene transcription, and Pin1 silencing also blocked cell proliferation, angiogenesis, and migration of TAMR-MCF-7 cells. Our findings suggest that the CYP3A4-mediated EET pathway represents a potential therapeutic target for the treatment of tamoxifen-resistant breast cancer.

Circulating tumor cells promote the metastatic colonization of disseminated carcinoma cells by inducing systemic inflammation

Circulating tumor cells (CTCs) have been studied well in the prognosis for malignant diseases as liquid biopsy, but their contribution to tumor metastasis is not clearly defined. Here we report that CTCs could promote the metastatic colonization of disseminated carcinoma cells by inducing systemic inflammation and neutrophil recruitment to pre-metastatic organs. Depletion of neutrophils in vivo could effectively abrogate the promoting effect of CTCs on tumor cell metastasis. In the presence of CTCs, the pro-tumor function of neutrophils was augmented, whereas the antitumor function of neutrophils was suppressed. Mechanically, CTC-derived ligands for TLR2 and TLR4 (TLR2/4) induced the systemic inflammation, thus increasing the production of proinflammatory cytokines such as G-CSF and IL-6 that could induce the conversion of neutrophil function from tumor-suppressing to tumor-promoting. Moreover, CTCs induced the production of endogenous TLR2/4 ligands such as S100A8, S100A9, and SAA3, which may amplify the stimulating effect that induces the expression of proinflammatory cytokines. The promoting effect of CTCs on tumor cell metastasis could be abrogated by suppressing inflammatory response with IL-37, an anti-inflammatory cytokine, or blocking CTC-derived ligands for TLR2/4. Identification of the metastatic axis of CTCs/systemic inflammation/neutrophils may provide potential targets for preventing tumor cell metastasis.