Amino acids and their roles in tumor immunotherapy of breast cancer

Breast cancer is the most commonly diagnosed cancer among women. The primary treatment options include surgery, radiotherapy, chemotherapy, targeted therapy and hormone therapy. The effectiveness of breast cancer therapy varies depending on the stage and aggressiveness of the cancer, as well as individual factors. Advances in early detection and improved treatments have significantly increased survival rates for breast cancer patients. Nevertheless, specific subtypes of breast cancer, particularly triple-negative breast cancer, still lack effective treatment strategies. Thus, novel and effective therapeutic targets for breast cancer need to be explored. As substrates of protein synthesis, amino acids are important sources of energy and nutrition, only secondly to glucose. The rich supply of amino acids enables the tumor to maintain its proliferative competence through participation in energy generation, nucleoside synthesis and maintenance of cellular redox balance. Amino acids also play an important role in immune-suppressive microenvironment formation. Thus, the biological effects of amino acids may change unexpectedly in tumor-specific or oncogene-dependent manners. In recent years, there has been significant progress in the study of amino acid metabolism, particularly in their potential application as therapeutic targets in breast cancer. In this review, we provide an update on amino acid metabolism and discuss the therapeutic implications of amino acids in breast cancer.     

Pilot study of gas chromatographic–mass spectrometric screening of newborn urine for inborn errors of metabolism after treatment with urease

Gas chromatographic–mass spectrometric (GC–MS) techniques for urinary organic acid profiling have been applied to high-risk screening for a wide range of diseases, mainly for inborn errors of metabolism (IEM), rather than to low-risk screening or mass screening. Using a simplified procedure with urease-pretreatment and the GC–MS technique, which allows simultaneous determination of organic acids, amino acids, sugars and sugar acids, we performed a pilot study of the application of this procedure to neonatal urine screening for 22 IEM. Out of 16 246 newborns screened, 11 cases of metabolic disorders were chemically diagnosed: two each of methylmalonic aciduria and glyceroluria, four of cystinuria, and one each of Hartnup disease, citrullinemia and α-aminoadipic aciduria/α-ketoadipic aciduria. The incidence of IEM was thus one per 1477, which was higher than the one per 3000 obtained in the USA in a study targeting amino acids and acylcarnitines in newborn blood spots by tandem mass spectrometry. Also, 227 cases were found to have transient metabolic abnormalities: 108 cases with neonatal tyrosinuria, 99 cases with neonatal galactosuria, and 20 cases with other transient metabolic disorders. Two hundred and thirty-eight cases out of 16 246 neonates (approximately 1/68) were thus diagnosed using this procedure as having either persistent or transient metabolic abnormalities.     

A simple method for the analysis by MS/MS of underivatized amino acids on dry blood spots from newborn screening

The analysis by electrospray-ionization tandem mass spectrometry of amino acids with butyl esterification and isotopically labeled internal standard is routine in newborn screening laboratories worldwide. In the present study, we established a direct analysis method of higher accuracy that uses a non-deuterated internal standard. The automatic sampler and the pump of an LC apparatus were used to inject sample and mobile phase to MS, but no LC column was needed. The dry blood spot (DBS) material was prepared at levels of low, medium and high concentration; the running time was 1 min. In parallel to the new procedure, we applied the established method to analyze nine amino acids on DBS of healthy newborns and phenylketonuria newborns. The newly proposed method of product ion confirmation scan along with multiple reaction monitoring resulted in a very accurate identification of each amino acid. Our innovative protocol had high sensitivity and specificity in the analysis of cases of suspected metabolic diseases.     

Serum trace element and amino acid profile in children with cerebral palsy

BackgroundThe existing data demonstrate that both trace elements and amino acids play a significant role in neurodevelopment and brain functioning. Certain studies have demonstrated alteration of micronutrient status in children with cerebral palsy, although multiple inconsistencies exist.The objectiveof the present study was to assess serum trace element and mineral, as well as amino acid levels in children with cerebral palsy.Methods71 children with cerebral palsy (39 boys and 32 girls, 5.7 ± 2.3 y.o.) and 84 healthy children (51 boys and 33 girls, 5.4 ± 2.3 y.o.) were enrolled in the present study. Serum trace element and mineral levels were assessed using inductively-coupled plasma mass-spectrometry (ICP-MS). Amino acid profile was evaluated by means of high-pressure liquid chromatography (HPLC).ResultsChildren with cerebral palsy are characterized by significantly lower Cu and Zn levels by 6% and 8%, whereas serum I concentration exceeded the control values by 7%. A tendency to increased serum Mn and Se levels was also observed in patients with cerebral palsy. Serum citrulline, leucine, tyrosine, and valine levels were 15 %, 23 %, 15 %, and 11 % lower than those in healthy controls. Nearly twofold lower levels of serum proline were accompanied by a 44 % elevation of hydroxyproline concentrations when compared to the control values. In multiple regression model serum I, Zn, and hydroxyproline levels were found to be independently associated with the presence of cerebral palsy. Correlation analysis demonstrated a significant correlation between Cu, Mn, Se, I, and Zn levels with hydroxyproline and citrulline concentrations.ConclusionThe observed alterations in trace element and amino acid metabolism may contribute to neurological deterioration in cerebral palsy. However, the cross-sectional design of the study does not allow to estimate the causal trilateral relationships between cerebral palsy, altered trace element, and amino acid metabolism.     

Gender related differences in the effect of aging on blood amino acid compartmentation☆

This work has been focused on the study of the variations in blood amino acid compartmentation (plasma and blood cells) with aging, both in men and women. Aging is a situation which, under the influence of gender, involves a decline in body weight functions and variations in energy metabolism with a deterioration of muscular metabolism leading to changes in amino acid handling. We determined the blood levels of individual amino acids in whole blood, plasma compartment and blood cell compartment of 51 men and 51 women. Subjects were classified in three age groups—AG1 (18 to 35 y), AG2 (35–50 y) and AG3 (more than 50 y). Aging was accompanied by significant changes in blood levels of amino acids showing gender-linked differences which were distinct for both blood compartments (plasma and blood cells). In men, aging was accompanied by a drop in blood levels of several amino acids, due mainly to the plasma compartment, whereas in women aging brought about a rise in blood levels of various amino acids mainly in blood cell compartment. This paper contributes to enhancing the physiological importance of the blood cell pool in the handling of amino acids.     

Free amino acids, copper, iron and zinc composition in sera of patients with thyrometabolic diseases

Free amino acids together with copper, iron and zinc were measured in sera of 67 adult patients with thyrotoxicosis (n = 29) or hypothyroidism (n = 38). In contradistinction to the almost indifferences exhibited by the three metals, many amino acids displayed significant relationships with the thyrometabolic activity (mainly tyrosine and arginine with r values of 0.5 and 0.44, respectively). Additional analyses revealed certain patterns, between trace metals and amino acids, which conferred challenging difficulties to interpretation. Thus while zinc was associated positively with some amino acids (such as glutamic acid and alanine), copper correlated almost invariably in a negative manner with citrulline, alpha-amino-butyric acid, proline, glycine and valine. This new information should contribute to our knowledge of the complex metabolism of both trace metals and amino acids.     

Determination of conjugated bile acids in human urine by high-performance liquid chromatography with chemiluminescence detection

A qualitative and quantitative analysis of the conjugated 1β- and 6α-hydroxy bile acids, including common bile acids, in human urine using high-performance liquid chromatography with chemiluminescence detection is described. After extraction of urine with C₁₈ silica cartridges, the bile acids were separated into non-conjugated, glycine, taurine and sulphate fractions by ion-exchange chromatography on a lipophilic gel. Solvolysis of the sulphate was carried out by treatment with trifluoroethanol in acetone containing hydrochloric acid, and the liberated amino acid conjugates were fractionated again. The individual bile acids were separated on a reversed-phase C₁₈ column (Bile Pak II), with detection by an immobilized 3α-hydroxysteroid dehydrogenase enzyme reactor and chemiluminescence reaction of the generated NADH using 1-methoxy-5-methylphenazinium methylsulphate—isoluminol—microperoxidase system. The assay method showed the detection limits ranging from 8 to 250 pmol for the bile acids tested. Analysis of urine samples obtained from newborns, non-pregnant women and women in late pregnancy showed a large difference in bile acid composition and conjugation mode, suggesting that bile acid metabolism is different during fetal and neonatal periods.     

Effects of prenatal morphine on hypothalamic metabolism of neurotransmitters and gonadal and adrenal activities,during the early postnatal period in the rat

It is noteworthy that exposure to opiates during fetal development results in permanent changes in adults related to morphological, behavioral and biochemical measures; however little is known concerning the effects of such drugs in early postnatal life. We investigated in newborn rats the effects of prenatal morphine-exposure on both—the hypothalamic metabolism of norepinephrine (NE), serotonin (5 HT) and neuropeptide Y (NPY)—the activity of the hypothalamo-pituitary gonadal and adrenal axes. In a previous study performed in newborns of untreated mothers, we reported some sex-dependent changes in the metabolism of NE, 5 HT and NPY in the hypothalamus and an early activation of the gonadostimulating function and of the corticostimulating one. In control newborns from saline-treated mothers, a slight increase in the hypothalamic metabolism of NE (males) and 5 HT (males and females) was observed and it was comparable in both sexes. On the other hand, the hypothalamic content of NPY was unaffected in early postnatal period in newborn males as well as in females. These changes observed on hypothalamic metabolisms are temporally correlated with the early postnatal activation of the corticostimulating function in neonates of both sexes and that of the gonadostimulating one, mainly in males. Prenatal morphine exposure altered the hypothalamic metabolism of 5 HT which was increased mainly in newborn females but did not affect either the metabolism of NE or the NPY content of the hypothalamus. The more drastic effect of the prenatal morphine treatment is the atrophy and hypoactivity of the adrenals in newborns of both sexes at birth time and during the early postnatal period. In contrast morphine did not impair postnatal surge of the plasma testosterone level in male pups as well as late and slight increase of plasma estradiol in female ones.     

Effect of zinc on L-threonine transport across the jejunum of rabbit

Zinc is an essential trace element for life. Many metalloenzymes involved in the metabolism of carbohydrates, lipids, protein, and nucleic acids require zinc for their functions. The aim of this study was to characterize how zinc acts on the intestinal amino acid absorption in rabbit. Results obtained show that zinc inhibits both L-threonine accumulation in the jejunum tissue, and mucosal-to-serosal transepithelial flux of this amino acid in a dose-dependent way. The inhibition does not increase by a 10-min previous intestinal exposure of the mucosa to the heavy metal, and is not reversed by washing the intestinal tissue with saline solution or 10mM EDTA, but is appreciably reversed with 10mM dithioerythritol. Zinc seems not to modify amino acid diffusion across the intestinal epithelium. The inhibition of intestinal amino acid transport by zinc seems to be of a competitive type, and appears to be a result of impairment of the active transport that is altered by its binding to proteins (prevailing to thiol groups) of the brush-border membrane of enterocytes.     

Effects of prenatal administration of nicotine on amino acid pools,protein metabolism,and nicotine binding in the brain

The effects of nicotine on brain protein metabolism and on the properties of the nicotine binding site were investigated in newborn animals exposed to nicotine during gestation. Brain protein synthesis rates measured in vivo were lower by 18% in newborn of treated animals. Protein degradation rates measured in vitro in the presence of nicotine were lower by 13%. The effect was specific forl-(-) nicotine, sinced-(+)nicotine, nicotinic acid, or nicotinamide had no effect on degradation rates. Newborn brain amino acid levels, mainly nonessential amino acids and amino acids of putative neurotrans nitter function, were changed some-what; an increase in the level of taurine (13%), threonine (21%), serine (35%) and glycine (35%), and a decrease in lysine (14%) was observed in the offspring of nicotine treated animals (0.5 mg/kg, s.c., 2×daily throughout gestation). These changes could not account for the decrease in protein metabolism. Nicotine binding was higher by 25% in the offspring of animals exposed to nicotine during gestation. No such increase was found after treatment of adult rats with nicotine, indicating that the properties of the nicotine binding site change with age.     

Bioelements in the treatment of burn injuries – The complex review of metabolism and supplementation (copper,selenium, zinc,iron, manganese,chromium and magnesium)

Appropriate nutrition is a key component of burn treatment and should be regarded as an integral part of the therapeutic process in burn patients. A nutritional intervention plan should not only allow for adequate quantities of energy and protein but also carefully consider the supply of macro- and micronutrients. As a result of the severe inflammatory response, oxidative stress, and hypermetabolic state, accompanied by often extensive exudation in burn patients, there is a considerable loss of macro- and micronutrients, including essential trace elements. This leads to certain complications, involving e.g. more frequent infections and impaired wound healing. Our current body of knowledge is still insufficient, and the studies carried out to date focus for the most part on the imbalances in trace elements, such as copper (Cu), selenium (Se), and zinc (Zn). Nevertheless, there are many other trace elements involved in immune functions, regulating gene expression or antioxidant defense, and many of those have not been properly investigated in a clinical setting. Due to the insufficient amount of unambiguous literature data and relatively few, often dated, studies carried out with small patient groups, further evaluation of macro- and microelements in burn patients seems indispensable, e.g. to bring up to date local nutritional protocols.     

Free amino acids in the late embryogenesis and pre-hatching stage of two coregonid fishes

Developing eggs of vendace (Coregonus albula L.) and whitefish (C. lavaretus L.) were experimentally delayed in hatching by incubation at low water temperature (1–2°). Some eggs were taken during this period to a water temperature which was gradually raised up to 8° to provoke mass hatching of embryos. The pattern of free amino acids was followed in eggs incubated at both temperatures. During a 56 days period, the content of several essential amino acids significantly decreased in eggs of both species. For instance, the lysine content dropped from 703 to 270 mg/g dry matter and the arginine content from 257 to 13.3 mg/100 g dry matter in whitefish eggs. A similar pattern of decreasing level of free amino acids in embryonated ova up to hatching was characteristic for essential amino acids and serine. Methionine was exceptional; its level remained approximately the same. On the other hand, non-essential amino acids showed a significant increase in concentration during the experimental period. For instance, the glycine level increased 4.9 and 2.1 times in whitefish and vendace eggs, respectively. Transfer of eggs to 8° accelerated the decrease of nearly all free amino acids before hatching. The consequence of such amino acid metabolism for newly hatched larvae is discussed.     

Determination of amino acid tissue concentrations by microdialysis: method evaluation and relation to plasma values

Summary. Microdialysis is an in vivo technique to monitor tissue concentrations of low molecular weight substances by means of a continuously perfused artificial capillary with a semipermeable membrane placed into the region of interest. The suitability of microdialysis to determine tissue concentrations of amino acids was evaluated in vitro by placing the catheter into Ringer buffer or into a plasma protein (50 g/l) solution containing 32 different amino acids (150 μmol/l each). All amino acids tested crossed freely the microdialysis membrane with recoveries close to 100%. Microdialysis fluid was sampled from subcutaneous tissue of five newborns and amino acid content analysed. Total and non protein bound amino acids were determined in the patients plasma by acid precipitation or ultrafiltration, respectively. Mean subcutaneous tissue concentrations were lower as compared to plasma for taurine, serine, alanine, aspartate, glutamate and ornithine and higher for valine, isoleucine, leucine, methionine, phenylalanine, tyrosine and arginine, indicating net uptake or release of amino acids from subcutaneous tissue. Thus, microdialysis offers a convenient and minimal invasive way to study tissue amino acid composition and appears to be a promising analytical tool for the study of amino acid metabolism in vivo. Received August 7, 2000 Accepted January 7, 2001     

Polyunsaturated fatty acids in serum lipids of reindeer during the close postnatal period

We examined serum fatty acid composition in reindeer during the close postnatal period (from <8 h to 3 weeks) by using maternal serum as a reference point and focusing on the proportions of polyunsaturated fatty acids (PUFAs) in serum lipids. A striking dissimilarity was found in the serum PUFAs between the neonatals and their mothers. In particular, the proportions of linoleic acid (18:2) and α-linolenic acid in serum cholesteryl esters and phospholipids of the newborn reindeer were significantly lower than those of the mothers. Furthermore, serum phospholipids of the newborns had lower arachidonic acid and docosapentaenoic acid but higher docosahexaenoic acid proportions than the maternal phospholipids. Although the proportions of the principal C18 PUFAs were low in reindeer milk, they increased sharply in serum cholesteryl esters and phospholipids of the calves during the first few days after birth. In particular, there were significant positive correlations in the proportions of 18:2 between serum and milk lipids. We conclude that the proportions of the serum C18 PUFAs are low in the newborn reindeer, but they are increased during the close perinatal period by a rate which suggests an efficient mechanism for selective retention of these fatty acids from milk lipids. Accepted: 10 August 1998     

氨基酸转运体在肿瘤代谢中的研究进展

代谢重编程是肿瘤的重要特征,是指肿瘤细胞为满足其快速增殖的生物合成与能量需求,对其糖代谢、脂代谢以及氨基酸代谢等代谢路径进行的重编程,以维持增长速度以及补偿能量代谢所造成的氧化还原压力。虽然不同的癌症代谢变化不同,但有些特征是所有癌症共有的,氨基酸代谢重编程是其中一个重要的特征。氨基酸进出细胞需要氨基酸转运体的协助,因而在肿瘤细胞中多种特定的氨基酸转运体均过表达。靶向氨基酸转运体通过影响肿瘤细胞的氨基酸代谢从而达到抗肿瘤的目的,是目前抗肿瘤药物的研究热点之一。主要介绍了几种在肿瘤代谢中发挥重要作用的氨基酸转运体以及靶向氨基酸转运体抗肿瘤治疗的研究进展及相关作用机制,旨在了解氨基酸转运体在抗肿瘤研究中的作用,以期促进靶向氨基酸转运体抗肿瘤药物的发展。     

Effect of acute intestinal obstruction on erythrocyte membrane function

The amino acid composition of red blood cell membrane proteins had been studied in different stages of acute intestinal obstruction. Hydrophobic amino acids were revealed to increase and glutamate was found to decrease during the early period of acute intestinal obstruction. Later neutral amino acids and some of the main amino acids were stated to decrease. Shifts in the ratio of protein fractions seen in red blood cell membrane of rats with acute intestinal obstruction could be explained by changes followed in the amino acid composition. The data accumulated had demonstrated that such a significant modification of protein component of the red blood cell membrane could be one of the reasons of the erythrocyte membrane penetrability violation and could play the pathogenetic role in the occurrence of irreversibility changes in cases of the intestinal obstruction. All that was mentioned above had shown the necessity to use membrane protectors and antienzyme drugs in the postoperative period.     

Changes in Macro- and Microelement Composition in the Organisms of Irradiated Animals

We studied the content of Al, Cd, Co, Cu, Fe, Mg, Mn, P, Pb, S, and Zn in the liver, kidneys, lungs, and spleen of mice with total radiation dose of 7.5 Gy using atomic emission spectral analysis with an inductively coupled argon plasma. The qualitative content of macro- and microelements and coordination between their concentrations statistically determined from coefficients of linear correlation differ between the tissues of the irradiated and control animals. Radiation damage decreases phosphorus content in all studied organisms and is a marker of disturbed conjugated oxidative phosphorylation. The most significant radiation-induced disturbance of macro- and microelement balance was detected in the spleen; it features decreased content of phosphorus, magnesium, and cobalt, as well as increased content of zinc and aluminum and considerably increased iron content. The revealed macro- and microelements disbalance in spleen, liver, kidneys, and lungs can be considered as a test for primary biological response to radiation damage.     

RF radiation-induced changes in the prenatal development of mice

The possible effects of radiofrequency (RF) radiation on prenatal development has been investigated in mice. This study consisted of RF level measurements and in vivo experiments at several places around an “antenna park.” At these locations RF power densities between 168 nW/cm² and 1053 nW/cm² were measured. Twelve pairs of mice, divided in two groups, were placed in locations of different power densities and were repeatedly mated five times. One hundred eighteen newborns were collected. They were measured, weighed, and examined macro- and microscopically. A progressive decrease in the number of newborns per dam was observed, which ended in irreversible infertility. The prenatal development of the newborns, however, evaluated by the crown-rump length, the body weight, and the number of the lumbar, sacral, and coccygeal vertebrae, was improved. Bioelectromagnetics 18:455–461, 1997. © 1997 Wiley-Liss, Inc.     

Experience of the Manitoba Perinatal Screening Program, 1965-85.

The Manitoba Perinatal Screening Program is guided by a committee of medical specialists with skills in the diagnosis and management of disorders of metabolism in the newborn. The program is voluntary and is centralized at Cadham Provincial Laboratory, in Winnipeg. A filter card blood specimen is collected from newborns on discharge from hospital, and a filter card urine sample is collected and mailed to the laboratory by the mother when the infant is about 2 weeks of age. The overall compliance rates for the blood and urine specimens are approximately 100% and 84% respectively. The blood specimen is screened for phenylalanine and other amino acids, thyroxine, galactose, galactose-1-phosphate and biotinidase. The urine specimen is screened for amino acids, including cystine, as well as methylmalonic acid and homocystine. Between 1965 and 1985, 83 cases of metabolic disorders were detected, including 23 cases of primary hypothyroidism, 14 of classic phenylketonuria, 5 of galactosemia variants, 3 of galactosemia, 2 of maple syrup urine disease and 1 of hereditary tyrosinemia. The direct cost per infant screened is $5.50, and the cost:benefit ratio is approximately 7.5:1. Maternal serum alpha-fetoprotein screening is being made available as the necessary supporting clinical facilities become available. On the basis of this experience, the author outlines the components that are important for an effective screening program.     

Physiology-biochemical properties of the cyanobacterium <Emphasis Type="Italic">Oscillatoria deflexa</Emphasis>

The optimal cultivation conditions for the cyanobacterium Oscillatoria deflexa were studied: temperature (25–27°C), pH (9.0–11.0), and illumination (7 klx). A nutrient medium providing for optimum cyanobacterium growth was selected, as well as media containing an aqueous extract of human urine ash and an inedible material of wheat and vegetables with added nitrates and bicarbonate. The chemical composition (macro and microelements, content of proteins, lipids, carbohydrates, and vitamins, amino acid and fatty acid composition, ash residue) of O. deflexe was studied for the first time. An analysis of the results indicates that O. deflexa is not inferior to the cyanobacterium Spirulina platensis and the green laver Chlorella vulgaris in practical use, for its mineral composition, content of vitamins, essential amino acids and fatty acids, and exceed them in its content of vitamin E and microelements, such as Fe, Mn, Ni. The bacterium’s ability to transport NaCl up to 30 g/l within the medium was studied, and its unique ability for survival and long-term storage was shown. The enhibitory effect of the biomass of O. deflexa on the germination of wheat grains, and growth of daphnids and rotifers was shown.