The linoleic acid metabolite, 13-HpODE augments the phosphorylation of EGF receptor and SHP-2 leading to their increased association

Understanding modulations of lipid mediators in cancer using a murine model of carcinomatous peritonitis

Background

Numerous studies have investigated the possible involvement of eicosanoids, lysophospholipids, and sphingolipids in cancer. We considered that comprehensive measurement of these lipid mediators might provide a better understanding of their involvement in the pathogenesis of cancer. In the present study, we attempted to elucidate the modulations of sphingolipids, lysophospholipids, diacyl‐phospholipids, eicosanoids, and related mediators in cancer by measuring their levels simultaneously by a liquid chromatography‐mass spectrometry method in a mouse model of carcinomatous peritonitis.

Methods

We investigated the modulations of these lipids in both ascitic fluid and plasma specimens obtained from Balb/c mice injected intraperitoneally with Colon‐26 cells, as well as the modulations of the lipid contents in the cancer cells obtained from the tumor xenografts.

Results

The results were as follows: the levels of sphingosine 1‐phosphate were increased, while those of lysophosphatidic acid (LysoPA), especially unsaturated long‐chain LysoPA, tended to be increased, in the ascitic fluid. Our findings suggested that ceramides, sphingomyelin, and phosphatidylcholine, their precursors, were supplied by both de novo synthesis and from elsewhere in the body. The levels of lysophosphatidylserine (LysoPS), lysophosphatidylinositol, lysophosphatidylglycerol, and lysophosphatidylethanolamine were also increased in the ascitic fluid, while those of phosphatidylserine (PS), a precursor of LysoPS, were markedly decreased. The levels of arachidonic acid derivatives, especially PGE2‐related metabolites, were increased, while the plasma levels of eicosanoids and related mediators were decreased. Comprehensive statistical analyses mainly identified PS in the ascitic fluid and eicosanoids in the plasma as having highly negative predictive values for cancer.

Conclusions

The results proposed many unknown associations of lipid mediators with cancer, underscoring the need for further studies. In particular, the PS/LysoPS pathway could be a novel therapeutic target, and plasma eicosanoids could be useful biomarkers for cancer.

Metabolite Comparison between Serum and Follicular Fluid of Dairy Cows with Inactive Ovaries Postpartum

Simple Summary

Although the milk production of dairy cows has increased rapidly in recent decades, the reproductive performance of dairy cows has gradually declined. In modern intensive dairy farms, prevention and treatment of inactive ovaries has become an important challenge of reproduction disorders during early lactation. Our aim is to screen out metabolites and metabolic pathways related to inactive ovaries through serum and follicular fluid metabolomics. We found that the changes in serum and follicular fluid were mainly enriched in nine metabolic pathways. In serum, these included d-glutamine and d-glutamate metabolism, alanine, aspartic and glutamate metabolism, arginine and proline metabolism, pentose and glucuronate interconversions, and glycerophospholipid metabolism. In follicular fluid, they were valine, leucine, and isoleucine biosynthesis; arachidonic acid metabolism; glycerophospholipid metabolism; starch and sucrose metabolism; phenylalanine metabolism; and pentose and glucuronate interconversion. The common metabolic pathways of disease-related serum and follicular fluid were pentose and glucuronate interconversions and glycerophospholipid metabolism. This research will provide a theoretical basis for exploring the causes of inactive ovaries and provide new ideas for the prevention and treatment of inactive ovaries in the future.

Abstract

Inactive ovaries (IO) accounts for 50% of ovarian disease in postpartum dairy cows, which seriously affects their reproductive efficiency. To investigate the metabolic changes in the serum and follicular fluid of dairy cows with IO during lactation, six estrus (E) cows and six IO cows at 50 to 55 days in milk were selected based on B ultrasonic detection and clinical manifestations. The differential metabolites in serum and follicular fluid between the E cows and IO cows were identified by ultra-high-pressure liquid chromatography–quadrupole time-of-flight mass spectrometry, combined with multidimensional statistical methods. The results showed that dairy cows with IO were in a subclinical ketosis status where beta-hydroxybutyrate (BHB) exceeded 1.20 mmol/L, 14 differential metabolites in the serum of IO cows included 10 increased metabolites and 4 decreased metabolites, and 14 differential metabolites in the follicular fluid of IO cows included 8 increased metabolites and 6 decreased metabolites. These differential metabolites mainly involved nine metabolic pathways. The common enrichment pathway of different metabolites in serum and follicular fluid were glycerophospholipid metabolism and pentose and glucuronate interconversions. In conclusion, there were significant differences in the differential metabolites and enrichment pathways between serum and follicular fluid of IO cows, implying that there were complex changes in blood metabolism and local follicular metabolism of IO cows, whose interactions need further investigation.

Long chain lipid hydroperoxides increase the glutathione redox potential through glutathione peroxidase 4

BACKGROUND

Peroxidation of PUFAs by a variety of endogenous and xenobiotic electrophiles is a recognized pathophysiological process that can lead to adverse health effects. Although secondary products generated from peroxidized PUFAs have been relatively well studied, the role of primary lipid hydroperoxides in mediating early intracellular oxidative events is not well understood.

METHODS

Live cell imaging was used to monitor changes in glutathione (GSH) oxidation in HAEC expressing the fluorogenic sensor roGFP during exposure to 9-hydroperoxy-10E,12Z-octadecadienoic acid (9-HpODE), a biologically important long chain lipid hydroperoxide, and its secondary product 9-hydroxy-10E,12Z-octadecadienoic acid (9-HODE). The role of hydrogen peroxide (H₂O₂) was examined by direct measurement and through catalase interventions. shRNA-mediated knockdown of glutathione peroxidase 4 (GPx4) was utilized to determine its involvement in the relay through which 9-HpODE initiates the oxidation of GSH.

RESULTS

Exposure to 9-HpODE caused a dose-dependent increase in GSH oxidation in HAEC that was independent of intracellular or extracellular H₂O₂ production and was exacerbated by NADPH depletion. GPx4 was involved in the initiation of GSH oxidation in HAEC by 9-HpODE, but not that induced by exposure to H₂O₂ or the low molecular weight alkyl tert-butyl hydroperoxide (TBH).

CONCLUSIONS

Long chain lipid hydroperoxides can directly alter cytosolic E_GSH independent of secondary lipid oxidation products or H₂O₂ production. NADPH has a protective role against 9-HpODE induced E_GSH changes. GPx4 is involved specifically in the reduction of long-chain lipid hydroperoxides, leading to GSH oxidation.

SIGNIFICANCE

These results reveal a previously unrecognized consequence of lipid peroxidation, which may provide insight into disease states involving lipid peroxidation in their pathogenesis.

Effect of heat stress on the porcine small intestine: a morphological and gene expression study

With the presence of global warming, the occurrence of extreme heat is becoming more common, especially during the summer, increasing pig susceptibility to severe heat stress. The aim of the current study was to investigate changes in morphology and gene expression in the pig small intestine in response to heat stress. Forty eight Chinese experimental mini pigs (Sus scrofa) were subjected to 40 degrees C for 5h each day for 10 successive days. Pigs were euthanized at 1, 3, 6, and 10 days after heat treatment and sections of the small intestine epithelial tissue were excised for morphological examination and microarray analyses. After heat treatment, the pig rectal temperature, the body surface temperature and serum cortisol levels were all significantly increased. The duodenum and jejunum displayed significant damage, most severe after 3 days of treatment. Microarray analysis found 93 genes to be up-regulated and 110 genes to be down-regulated in response to heat stress. Subsequent bioinformatic analysis (including gene ontology and KEGG pathway analysis) revealed the genes altered in response to heat stress related to unfolded protein, regulation of translation initiation, regulation of cell proliferation, cell migration and antioxidant regulation. Heat stress caused significant damage to the pig small intestine and altered gene expression in the pig jejunum. The results of the bioinformatic analysis from the present study will be beneficial to further investigate the underlying mechanisms involved in heat stress-induced damage in the pig small intestine.

Arachidonic Acid metabolites in the cardiovascular system: the role of lipoxygenase isoforms in atherogenesis with particular emphasis on vascular remodeling

Vascular remodeling refers to lasting structural alterations in the vessel wall that are initiated in response to external and internal stimuli. These changes are distinct from acute functional responses of blood vessels when challenged by increased blood pressure, altered hemodynamics, or vasoactive mediators. In early atherogenesis, when lesion formation is starting to impact local hemodynamics, the vessel wall responds with outward vascular remodeling to maintain normal blood flow. However, inward remodeling may also occur during the time course of plaque formation, contributing to vascular stenosis. Lipoxygenases form a heterogeneous family of lipid-peroxidizing enzymes, which have been implicated in atherogenesis. Several lines of in vitro and in vivo evidence indicated their involvement in disease development, but the precise function of different lipoxygenase isoforms is still a matter of discussion. Vascular remodeling is an early response during plaque development; therefore, lipoxygenases may be involved in this process. Unfortunately, little is known about the potential role of lipoxygenase isoforms in vascular remodeling. This review will briefly summarize our knowledge of the role of lipoxygenases in vascular biology and will critically review the activities of the 3 most athero-relevant lipoxygenase isoforms in atherogenesis, with particular emphasis on vascular remodeling.

Levels of expression of lipoxygenases and cyclooxygenase-2 in human breast cancer

Lipoxygenases and cyclooxygenase are key mediators of arachidonic acid metabolism. The eicosanoids metabolites from these oxygynases have been shown to regulate the growth and death of cancer cells. This study determined the level of expression of 5-, 12-, 15-lipoxygenase and cyclooxygenase-2 expression in a cohort of breast cancer patients and their correlation with clinical outcomes. Compared with normal breast tissues, tumour tissues exhibited a significantly higher levels of 12-lipoxygenase and cyclooxygenase-2 (P<0.05), and significantly lower level of 15-lipoxygenase (P=0.05). Lobular carcinomas had a higher level of cyclooxygenase-2 and lower level of 15-lipoxygenase than ductal carcinomas. The lowest level of 15-lipoxygenase was seen in TNM3 and TNM4 tumours and from patients who died of breast cancer. Levels of 12- and 5-lipoxygenases were also particularly high in tumours from patients who died of breast cancer. This study shows that human breast tumours aberrantly express lipoxygenases and cyclooxygenase-2 and that decreased level of 15-lipoxygenase and raised level of cyclooxygenase-2 and 12-lipoxygenase has prognostic value in patients with breast cancer.

The effect of 15-lipoxygenase-1 expression on cancer cells

Lipoxygenases oxidatively metabolize polyunsaturated fatty acids to a rich spectrum of biologically active products. One enzyme of the lipoxygenase family, Arachidonate 15-lipoxygenase-1 (arachidonate:oxygen 15-oxidoreductase, EC 1.13.11.33), is implicated in several forms of epithelial cell cancers, and provides a rationale for exploring its role in the progression and metastasis of cancers. Thus, 15-LO-1 could be a marker of the growth and spread of cancers. The importance of 15-LO-1 expression is imparted by its metabolic product of linoleic acid, yielding 13-(S)-hydroxyoctadecadienoic acid (13-(S)-HODE). In order to maximize our understanding of the roles of lipoxygenases and cyclooxygenases in cancer, it is necessary to correlate their metabolic pathways to the respective expression levels, and not exaggerate the presence or absence of an enzyme or its function when it clearly is not there. It is also important to acknowledge that some forms of these enzymes may not even be relevant to human disease. Although it is unlikely that any single gene is sufficient to account for the complex etiology of cancer, 15-LO-1 overexpression is clearly a key component in the cell proliferation process. This article is divided into three sections emphasizing the key role of 15-LO-1 in prostate, colorectal, and breast cancers.

Expression of Gab1 lacking the pleckstrin homology domain is associated with neoplastic progression

An in vitro transformation system of carcinogen-treated Syrian hamster embryo (SHE) cell cultures represents multistep genetic and nongenetic changes that develop during the neoplastic progression of normal cells to tumor cells in vivo. During this neoplastic progression, SHE cells demonstrate an altered response to epidermal growth factor (EGF). In the present report, we examined the role of the adapter protein Gab1 (Grb2-associated binder-1) in the neoplastic progression of SHE cells. We used two asbestos-transformed SHE cell clones in different neoplastic stages: a 10W+8 clone, which is immortal and retains the ability to suppress the tumorigenicity of tumor cells in cell-cell hybrid experiments, and a 10W-1 clone, which has lost this tumor suppressor ability. 10W+8 cells expressed full-length 100-kDa Gab1 and associated 5.2-kb mRNA. Upon repeated cell passaging, 10W-1 cells showed increasing expression of a novel 87-kDa form of Gab1 as well as 4.6-kb mRNA with diminishing expression of the original 100-kDa Gab1. cDNA encoding the 87-kDa Gab1 predicts a form of Gab1 lacking the amino-terminal 103 amino acids (Gab1(Delta1-103)), which corresponds to loss of most of the pleckstrin homology (PH) domain. Gab1(Delta1-103) retains the ability to be phosphorylated in an EGF-dependent manner and to associate with the EGF receptor and SHP-2 upon EGF stimulation. The endogenous expression of Gab1(Delta1-103) in 10W-1 cells appeared closely related to EGF-dependent colony formation in soft agar. Moreover, transfection and expression of Gab1(Delta1-103), but not Gab1, in 10W+8 cells enhanced their EGF-dependent colony formation in soft agar. These results demonstrate that Gab1 is a target of carcinogen-induced transformation of SHE cells and that the expression of a Gab1 variant lacking most of the PH domain plays a specific role in the neoplastic progression of SHE cells.