Plasma free amino acid profiles of canine mammary gland tumors

Plasma amino acid profiles of dogs with the hepatocutaneous syndrome and dogs with other chronic liver diseases

BACKGROUND

Dogs with hepatocutaneous syndrome (HCS) have marked plasma hypoaminoacidemia, but its occurrence in dogs with chronic liver diseases not associated with HCS (non-HCS CLD) is unknown.

OBJECTIVES

To determine if plasma hypoaminoacidemia occurs in dogs with non-HCS CLD, compare plasma amino acid (PAA) profiles between dogs with non-HCS CLD and HCS, and define a sensitive and specific PAA pattern for diagnosing HCS.

ANIMALS

Data were collected from client-owned dogs, a prospective cohort of 32 with CLD and 1 with HCS, and a retrospective cohort of 7 with HCS.

METHODS

Prospective study. Dogs with chronic serum liver enzyme increases were recruited after hepatic biopsy. Plasma amino acid profiles were measured using high-performance liquid chromatography. Plasma amino acid concentrations were compared between dogs with non-HCS CLD and HCS. Regression analysis was performed to identify a unique PAA pattern for HCS diagnosis.

RESULTS

Twelve dogs each with vacuolar hepatopathy or chronic hepatitis and 8 dogs with congenital disorders (primary hypoplasia of the portal vein or ductal plate malformations) were enrolled. Compared to non-HCS CLD dogs, HCS dogs had significantly lower plasma concentrations of several amino acids. Regression analysis revealed that glutamine, glycine, citrulline, arginine, and proline concentrations less than 30% of the mean reference value had 100% sensitivity, specificity for diagnosing HCS.

CONCLUSIONS AND CLINICAL IMPORTANCE

Generalized plasma hypoaminoacidemia does not accompany non-HCS CLD. Concentrations of 5 specific amino acids less than 30% of the mean reference value can serve as a noninvasive biomarker for diagnosing HCS.

Metabolic Alterations in Canine Mammary Tumors

Canine mammary tumors (CMTs) are among the most common diseases in female dogs and share similarities with human breast cancer, which makes these animals a model for comparative oncology studies. In these tumors, metabolic reprogramming is known as a hallmark of carcinogenesis whereby cells undergo adjustments to meet the high bioenergetic and biosynthetic demands of rapidly proliferating cells. However, such alterations are also vulnerabilities that may serve as a therapeutic strategy, which has mostly been tested in human clinical trials but is poorly explored in CMTs. In this dedicated review, we compiled the metabolic changes described for CMTs, emphasizing the metabolism of carbohydrates, amino acids, lipids, and mitochondrial functions. We observed key factors associated with the presence and aggressiveness of CMTs, such as an increase in glucose uptake followed by enhanced anaerobic glycolysis via the upregulation of glycolytic enzymes, changes in glutamine catabolism due to the overexpression of glutaminases, increased fatty acid oxidation, and distinct effects depending on lipid saturation, in addition to mitochondrial DNA, which is a hotspot for mutations. Therefore, more attention should be paid to this topic given that targeting metabolic fragilities could improve the outcome of CMTs.

Metabolite profiling in sphere-forming cells from canine mammary adenocarcinoma cell lines using gas chromatography-mass spectrometry

Cancer consists of heterogeneous cells that contain a small population of cells that possess stem cell properties; these cells, referred to as cancer stem cells (CSCs) or tumor-initiating cells, are involved in tumor progression and metastasis. Using a sphere-forming assay, canine mammary CSCs were found to be similar to human breast CSCs. Metabolic reprogramming has been recognized as a hallmark of various cancers. However, the significance of cellular metabolism in CSCs remains unclear. The aim of this study was to define the metabolic characteristics of CSCs derived from canine mammary tumors and gain an understanding of the maintenance of stemness. We identified metabolite profiles of canine mammary adenocarcinoma cell lines using gas chromatography-mass spectrometry. Metabolites were extracted from both adherent and sphere-forming cells derived from three cell lines. Sphere-forming cells were separated from adherent cells using an orthogonal, partial least-squares discriminant analysis. Sphere-forming cells were found to contain high levels of the amino acids alanine, glycine and proline compared with adherent cells. They also had high levels of palmitoleate, palmitate and dihomo-gamma-linolenic acid compared with adherent cells. In a sphere-forming assay, palmitate increased the number of spheres for all cell lines. These results indicate that the sphere-forming cells derived from canine mammary adenocarcinoma cell lines have specific metabolic profiles that may be useful for the development of CSC-specific therapies targeting metabolic pathways and potential stemness biomarkers; these results also clarify the maintenance of stemness in canine mammary CSCs.

Plasma-free amino acid profiles in dogs with hepatocellular carcinoma

BACKGROUND

Metabolomic analysis using blood samples has been suggested to be useful for the early detection of cancer. Among metabolites, plasma-free amino acid (PFAA) profiles are potential diagnostic biomarkers for several diseases including cancer. However, the relationship between PFAA concentrations and liver tumors in dogs remains unknown.

OBJECTIVE

To determine the characteristics of PFAA profiles of dogs with hepatocellular carcinoma (HCC) and correlated clinical features.

ANIMALS

Thirty-four client-owned dogs diagnosed with HCC (n = 26) and benign liver diseases (n = 8) and 11 age-matched healthy dogs.

METHODS

Prospective study using heparinized blood samples from fasted dogs. Plasma was deproteinized, and the concentrations of 21 amino acids were measured using an automated high-performance liquid chromatography amino acid analyzer.

RESULTS

Plasma glutamic acid concentrations were significantly different among groups (P < .0024 after Bonferroni correction). Compared to healthy dogs, dogs with HCC and benign liver diseases had significantly higher concentrations of glutamic acid by post hoc analysis. However, no significant difference in the PFAA profiles of HCC and benign liver diseases were detected. In addition, preoperative and postoperative PFAA profiles of dogs with HCC were not significantly different.

CONCLUSIONS AND CLINICAL IMPORTANCE

Increased glutamic acid concentrations might play a role in the development or be a consequence of liver tumor formation. However, PFAA profiles of HCC could not be differentiated from those of benign lesions. In addition, glutamic acid concentrations did not change after surgical resection. These results indicate that PFAA profiles may not be useful biomarkers for detecting HCC in dogs.

Plasma amino acid profiles in dogs with inflammatory bowel disease

BACKGROUND

Lymphocytic-plasmacytic enteritis is the common form of idiopathic inflammatory bowel disease (IBD) in dogs. In human IBD, disturbances of amino acid metabolism have been demonstrated to be involved in the pathophysiology of IBD. Therefore, plasma amino acid profile might represent a novel marker of human IBD.

OBJECTIVES

To determine the plasma amino acid profiles of dogs with IBD and its usefulness as a novel marker of IBD in dogs.

ANIMALS

Fasting blood plasma was obtained from 10 dogs with IBD and 12 healthy dogs.

METHODS

All IBD dogs were prospectively included in this study, and heparinized blood samples were collected. The plasma concentrations of 21 amino acids were determined using the ninhydrin method. The relationships among the plasma amino acid concentrations and plasma C-reactive protein (CRP) concentration, canine chronic enteropathy clinical activity index (CCECAI), and overall World Small Animal Veterinary Association (WSAVA) score were investigated.

RESULTS

Median concentration (nmol/mL) of methionine [46.2; range, 30.0-59.3], proline [119.4; range, 76.7-189.2], serine [115.1; range, 61.4-155.9], and tryptophan [17.4; range, 11.9-56.3]) were significantly lower than in control dogs [62.6; range, 51.0-83.6, 199.1; range, 132.5-376.7, 164.3; range, 124.7-222.9, and 68.3; range, 35.7-94.8, respectively]. A negative correlation was identified between the plasma serine concentration and CCECAI (r _s = -.67, P = .03), but there were no correlations between plasma amino acid concentrations and CRP concentration or overall WSAVA score.

CONCLUSIONS AND CLINICAL IMPORTANCE

Plasma serine concentration might represent a novel maker of IBD in dogs.

Analysis of plasma free amino acid profiles in canine brain tumors

Canine brain tumors are best diagnosed using magnetic resonance imaging (MRI). However, opportunities of MRI examination are restricted due to its limited availability in veterinary facilities; thus, numerous canine brain tumors are diagnosed at an advanced stage. Therefore, development of a noninvasive diagnostic biomarker is required for the early detection of brain tumors. In the present study, plasma free amino acid (PFAA) profiles between dogs with and without brain tumors were compared. A total of 12 dogs with brain tumors, diagnosed based on clinical signs, and on the results of intracranial MRI and/or pathological examination were evaluated. In addition, eight dogs diagnosed with idiopathic epilepsy and 16 healthy dogs were also included. A liquid chromatography system with automated pre-column derivatization functionality was used to measure the levels of 20 amino acids. As a result, the levels of three amino acids (alanine, proline and isoleucine) were increased significantly (1.6-, 1.5- and 1.6-fold, respectively) in the plasma of dogs with brain tumors as compared with the levels in control dogs (all P<0.05). Thus, the PFAA levels of dogs with brain tumors differed from those of healthy dogs. The present study demonstrated that analysis of PFAA levels of dogs with brain tumors may serve as a useful biomarker for the early detection of canine brain tumors.

Application of Pre-Column Labeling Liquid Chromatography for Canine Plasma-Free Amino Acid Analysis

Plasma-free amino acid (PFAA) levels are a useful metric for diagnosing cancer and providing a prognosis. However, the use of analysis of PFAA levels has been limited in the veterinary medicine field. We addressed the application of liquid chromatography (LC) using a pre-column labeling technique for analysis of canine PFAA levels. This method significantly shortened the analysis time relative to conventional methods. No diurnal fluctuations were detected at 9:00 AM in most PFAA levels, and food intake increased the levels of some PFAAs, including valine, leucine, tyrosine, phenylalanine, and proline. These results indicate that LC with pre-column labeling is useful for measuring canine PFAA levels, for which time of day and interval after food intake must be taken into consideration.

Ornithine ingestion improved sleep disturbances but was not associated with correction of blood tryptophan ratio in Japanese Antarctica expedition members during summer

Members of expeditions to Antarctica may show changes in biological and physiological parameters involved in lipid, glucose, and thyroid hormone metabolism as they adapt to the environment; however, alterations in amino acid (AA) levels and sleep among expedition members in Antarctica have yet to be fully elucidated. We hypothesized that there would be alterations of blood AA levels, and ornithine (Orn) ingestion would affect biological parameters and sleep in Japanese expedition members during the summer in Antarctica. Japanese Antarctica Research Expedition members (22 people) who stayed in Antarctica for 3 months from December 2010 were examined, and a randomized double-blind study of Orn ingestion (400 mg/d) for 4 weeks was performed. Sleep conditions were evaluated subjectively by the Oguri-Shirakawa-Azumi (brief version) questionnaire. The blood of Japanese Antarctica Research Expedition members in Antarctica showed higher creatine kinase, lactate dehydrogenase, and ammonia levels than that in Japan. On blood AA analysis, aspartate, Orn, and serine were significantly higher, and alanine and tryptophan (Trp) were significantly lower in Antarctica than in Japan. The Trp ratio, the value of Trp divided by the sum of phenylalanine, tyrosine, and branched-chain AAs, was significantly lower in Antarctica than in Japan. Although sleep deteriorated during the stay in Antarctica, Orn ingestion, to some extent, improved sleep compared with the placebo group in Antarctica, suggesting that Orn is effective for people with heavy physical workloads in places such as Antarctica.