Protein and amino acid metabolism in cancer cachexia: investigative techniques and therapeutic interventions

Precision detection of select human lung cancer biomarkers and cell lines using honeybee olfactory neural circuitry as a novel gas sensor

Human breath contains biomarkers (odorants) that can be targeted for early disease detection. It is well known that honeybees have a keen sense of smell and can detect a wide variety of odors at low concentrations. Here, we employ honeybee olfactory neuronal circuitry to classify human lung cancer volatile biomarkers at different concentrations and their mixtures at concentration ranges relevant to biomarkers in human breath from parts-per-billion to parts-per-trillion. We also validated this brain-based sensing technology by detecting human non-small cell lung cancer (NSCLC) and small cell lung cancer (SCLC) cell lines using the 'smell' of the cell cultures. Different lung cancer biomarkers evoked distinct spiking response dynamics in the honeybee antennal lobe neurons indicating that those neurons encoded biomarker-specific information. By investigating lung cancer biomarker-evoked population neuronal responses from the honeybee antennal lobe, we classified individual human lung cancer biomarkers successfully (88% success rate). When we mixed six lung cancer biomarkers at different concentrations to create 'synthetic lung cancer' vs. 'synthetic healthy' human breath, honeybee population neuronal responses were able to classify those complex breath mixtures reliably with exceedingly high accuracy (93-100% success rate with a leave-one-trial-out classification method). Finally, we employed this sensor to detect human NSCLC and SCLC cell lines and we demonstrated that honeybee brain olfactory neurons could distinguish between lung cancer vs. healthy cell lines and could differentiate between different NSCLC and SCLC cell lines successfully (82% classification success rate). These results indicate that the honeybee olfactory system can be used as a sensitive biological gas sensor to detect human lung cancer.

Real-World Pharmacokinetics, Effectiveness, and Safety of Atezolizumab in Patients With Unresectable Advanced or Recurrent NSCLC: An Exploratory Study of J-TAIL

Introduction

This study validated real-world pharmacokinetic (PK) data using an established population PK (PopPK) model for atezolizumab in Japanese patients with NSCLC and explored the relationship between PK parameters, effectiveness, and adverse events (AEs) for the 1200 mg once every three weeks regimen.

Methods

A subgroup of 262 of 1039 patients from J-TAIL consented to this exploratory research for PK evaluation of atezolizumab monotherapy for unresectable advanced/recurrent NSCLC (August 2018 to October 2019; 197 institutions). We evaluated plasma concentrations before the start of the third cycle of atezolizumab infusion classified into quartiles 1 to 4, their association with effectiveness, and the association between atezolizumab maximum plasma concentrations (Cmax) calculated using the existing PopPK model and AEs of special interest (AESIs).

Results

Overall, 175 of 262 patients were included; baseline characteristics were similar to those of patients enrolled in J-TAIL (Eastern Cooperative Oncology Group performance status ≥ 2, 12.0%; age ≥ 75 y, 28.9%; atezolizumab as more than or equal to third-line treatment, 57.5%). Atezolizumab plasma concentrations were similar to previously reported data among Japanese/non-Japanese patients. The overall survival was significantly shorter in patients with lower atezolizumab plasma concentrations in Q1 versus Q2 to Q4, although progression-free survival remained the same. The PK data adequately fit the PopPK model, with the frequency of AESIs increasing as the calculated Cmax at cycle 1 increased.

Conclusions

In real-world Japanese patients with unresectable advanced/recurrent NSCLC, PKs were similar to previous reports. Certain patient populations had shorter overall survival, and atezolizumab plasma concentrations in cycle 3 were lower in this population. Elevated Cmax at cycle 1 may be associated with an increased frequency of AESIs.

Update on the treatment of cancer cachexia

Cancer cachexia is a complex multifaceted syndrome involving functional impairment and changes in body composition that cannot be reversed by nutritional support. Cancer cachexia is characterized by decreased skeletal muscle mass, increased lipolysis, and decreased food intake. Cancer cachexia decreases chemotherapy tolerance as well as quality of life. However, because no fully effective interventions are available, cancer cachexia remains an unmet need in cancer treatment. In recent years, several discoveries and treatments for cancer cachexia have been studied, and guidelines have been published. We believe that the development of effective strategies for the diagnosis and treatment of cancer cachexia will lead to breakthroughs in cancer treatment.

SLC1A5 regulates cell proliferation and self-renewal through β-catenin pathway mediated by redox signaling in arsenic-treated uroepithelial cells

Arsenic exposure increases the risk of bladder cancer in humans, but its underlying mechanisms remain elusive. The alanine, serine, cysteine-preferring transporter 2 (ASCT2, SLC1A5) is frequently overexpressed in cancer cells. The aim of this study was to evaluate the effects of arsenic on SLC1A5, and to determine the role of SLC1A5 in the proliferation and self-renewal of uroepithelial cells. F344 rats were exposed to 87 mg/L NaAsO₂ or 200 mg/L DMA^V for 12 weeks. The SV-40 immortalized human uroepithelial (SV-HUC-1) cells were cultured in medium containing 0.5 μM NaAsO₂ for 40 weeks. Arsenic increased the expression levels of SLC1A5 and β-catenin both in vivo and in vitro. SLC1A5 promoted cell proliferation and self-renewal by activating β-catenin, which in turn was dependent on maintaining GSH/ROS homeostasis. Our results suggest that SLC1A5 is a potential therapeutic target for arsenic-induced proliferation and self-renewal of uroepithelial cells.

Tissue and plasma free amino acid detection by LC-MS/MS method in high grade glioma patients

PURPOSE

The changes in serum amino acid profiles are evaluated in different types of cancers and screening tests were developed for estimating the risk of cancer by rapid analysis of plasma free amino acid (PFAA) levels. There is scarce evidence about the metabolomics analysis of PFAA in malignant gliomas. The aim of the present study was to identify the most promising diagnostic amino acid biomarkers that could be objectively measured for high-grade glioma and to compare their level with the tissue counterpart.

METHODS

In this prospective study, we collected serum samples from 22 patients with the pathological diagnosis of high-grade diffuse glioma according to WHO 2016 classification and 22 healthy subjects, and brain tissue from 22 controls. Plasma and tissue amino acid concentrations were analyzed applying liquid chromatography-tandem mass spectrometry (LC-MS/MS) method.

RESULTS

Serum alanine, alpha-aminobutyric acid (AABA), lysine (Lys) and cysteine concentrations were significantly higher in high-grade glioma patients despite low levels of alanine and Lys in the tumor tissue. Aspartic acid, histidine and taurine were significantly decreased in both serum and tumors of glioma patients. A positive correlation was detected between tumor volumes and serum levels of latter three amino acids.

CONCLUSION

This study demonstrated potential amino acids which may have diagnostic value for high-grade glioma patients by utilizing LC-MS/MS method. Our results are preliminary to compare serum and tissue levels of amino acids in patients with malignant gliomas. The data presented here may provide feature ideas about the metabolic pathways in the pathogenesis of gliomas.

Plasma Amino Acids in Horses Suffering from Pituitary Pars Intermedia Dysfunction

Pituitary pars intermedia dysfunction is one of the most common diseases of aged horses and ponies. In Parkinson's disease, which is, similar to PPID, a disease that involves oxidative damage to dopaminergic pathways but with different clinical signs, alterations to the serum amino acid profile have been reported. To examine changes in the plasma amino acid profile in horses with PPID, EDTA plasma of horses that were presented for various reasons that required laboratory examinations of blood anticoagulated with EDTA was collected. With this plasma, the basal ACTH concentration as well as the amino acid profile was determined. Horses were considered PPID patients if the ACTH concentration was ≥ 100 pg/mL, i.e., they would be considered affected at any time. Horses were defined as non-PPID (nPPID) patients if the ACTH concentration was below 30 pg/mL. Horses receiving pergolide with ACTH ≤ 30 pg/mL were allocated to the group PPIDrr (PPID, ACTH in reference range) and horses receiving pergolide with ACTH ≥ 100 pg/mL to the group PPIDarr (PPID, ACTH above reference range). In total, 93 horses were examined, including 88 horses at the clinic and 5 horses at a private practice. Of these, 53 horses fulfilled the inclusion criteria (ACTH ≤ 30 pg/mL or ACTH ≥ 100 pg/mL). A total of 25 horses were diagnosed as nPPID, 20 as PPID, 5 as PPIDrr, and 3 as PPIDarr. Arginine was significantly higher in PPIDrr than in PPID and nPPID, asparagine was significantly higher in PPID, PPIDrr, and PPIDarr than in nPPID, citrulline was significantly higher in PPIDrr than in nPPID and PPID, cysteine was significantly lower in PPIDrr than in PPID, nPPID, and PPIDarr, and glutamine was significantly higher in PPID and PPIDarr than in nPPID. Especially, asparagine, citrulline, and glutamine may be potential diagnostic markers and may offer interesting approaches for research regarding amino supplementation in PPID.

Thin-layer chromatography of DNS amino acids derivatives in systems with silica gel and silanized silica gel plates

Investigations into separation selectivity of High-Performance Thin-layer chromatography (HPTLC) of dansyl (DNS) derivatives of amino acids in silica gel (Silica gel 60 F254s plates) and silanized silica gel (RP-18 W plates) systems are presented. The results have been obtained for mobile phases containing different concentrations of acetonitrile (ACN) in formic acid (FA) water solution (final concentration of FA in the mobile phase was equal to 265 mmol/dm3). The data obtained show differences in separation selectivity of the solutes between employment of HPTLC silica gel and RP-18 W systems.

Tryptophan and Its Metabolites in Lung Cancer: Basic Functions and Clinical Significance

Lung cancer is the most lethal malignancy worldwide. Recently, it has been recognized that metabolic reprogramming is a complex and multifaceted factor, contributing to the process of lung cancer. Tryptophan (Try) is an essential amino acid, and Try and its metabolites can regulate the progression of lung cancer. Here, we review the pleiotropic functions of the Try metabolic pathway, its metabolites, and key enzymes in the pathogenic process of lung cancer, including modulating the tumor environment, promoting immune suppression, and drug resistance. We summarize the recent advance in therapeutic drugs targeting the Try metabolism and kynurenine pathway and their clinical trials.

Pressurized planar electrochromatography of DNS amino acids derivatives in silica gel and silanized silica gel systems with formic acid addition to the water mobile phase

Pressurized planar electrochromatography (PPEC) of dansyl (DNS) derivatives of amino acids in normal- and reversed-phase systems is presented. The results have been obtained for mobile phases with different acetonitrile (ACN) concentrations (0–85%). The data obtained show differences in separation selectivity between high-performance thin-layer chromatography (HPTLC) and PPEC systems. These differences originate from the electrophoretic effect which is involved in the PPEC system, contrary to the HPTLC one.

Targeting SLC1A5 blocks cell proliferation through inhibition of mTORC1 in arsenite-treated human uroepithelial cells

Arsenic is an environmental contaminant, which is widely distributed in soil, air, and water. There is sufficient evidence to indicate that arsenic increases the risk of bladder cancer in humans. However, its underlying mechanisms remain elusive. Glutamine (Gln) has multiple functions that promote carcinogenesis. Indeed, Gln transporters on cancer cells surface are often upregulated. Elevated expression levels of Alanine, serine, cysteine-preferring transporter 2 (ASCT2; SLC1A5) have been reported in many types of human tumors. This study characterized the role of SLC1A5 in cell proliferation in arsenite-treated cells. In short-term experiments, SV-40 immortalized human uroepithelial (SV-HUC-1) cells were treated with Sodium arsenite (NaAsO₂) (0, 0.5, 1, 2, 4, 8 μM) for 24 h. In long-term experiments, SV-HUC-1 cells were exposed to 0.5 μM NaAsO₂ for 40 weeks. In both short-term and long-term experiments, arsenite increased expression of SLC1A5 by 1.89-fold and 2.25-fold, respectively. Arsenite increased Gln consumption of SV-HUC-1 cells, and Gln starvation inhibited cell proliferation in long-term arsenite-treated cells. Importantly, inhibiting SLC1A5 blocked cell proliferation by downregulating mTORC1 in long-term arsenite-treated cells. Moreover, SLC1A5 regulated mTORC1 in an αKG-dependent manner. Our results suggest that SLC1A5 plays an important role in cell proliferation of arsenite-treated SV-HUC-1 cells.

Aerobic Exercise Ameliorates Cancer Cachexia-Induced Muscle Wasting through Adiponectin Signaling

Cachexia is a multifactorial syndrome characterized by muscle loss that cannot be reversed by conventional nutritional support. To uncover the molecular basis underlying the onset of cancer cachectic muscle wasting and establish an effective intervention against muscle loss, we used a cancer cachectic mouse model and examined the effects of aerobic exercise. Aerobic exercise successfully suppressed muscle atrophy and activated adiponectin signaling. Next, a cellular model for cancer cachectic muscle atrophy using C2C12 myotubes was prepared by treating myotubes with a conditioned medium from a culture of colon-26 cancer cells. Treatment of the atrophic myotubes with recombinant adiponectin was protective against the thinning of cells through the increased production of p-mTOR and suppression of LC3-II. Altogether, these findings suggest that the activation of adiponectin signaling could be part of the molecular mechanisms by which aerobic exercise ameliorates cancer cachexia-induced muscle wasting.

Derangements of amino acids in cachectic skeletal muscle are caused by mitochondrial dysfunction

BACKGROUND

Cachexia is the direct cause of at least 20% of cancer-associated deaths. Muscle wasting in skeletal muscle results in weakness, immobility, and death secondary to impaired respiratory muscle function. Muscle proteins are massively degraded in cachexia; nevertheless, the molecular mechanisms related to this process are poorly understood. Previous studies have reported conflicting results regarding the amino acid abundances in cachectic skeletal muscle tissues. There is a clear need to identify the molecular processes of muscle metabolism in the context of cachexia, especially how different types of molecules are involved in the muscle wasting process.

METHODS

New in situ -omics techniques were used to produce a more comprehensive picture of amino acid metabolism in cachectic muscles by determining the quantities of amino acids, proteins, and cellular metabolites. Using matrix-assisted laser desorption/ionization (MALDI) mass spectrometry imaging, we determined the in situ concentrations of amino acids and proteins, as well as energy and other cellular metabolites, in skeletal muscle tissues from genetic mouse cancer models (n = 21) and from patients with cancer (n = 6). Combined results from three individual MALDI mass spectrometry imaging methods were obtained and interpreted. Immunohistochemistry staining for mitochondrial proteins and myosin heavy chain expression, digital image analysis, and transmission electron microscopy complemented the MALDI mass spectrometry imaging results.

RESULTS

Metabolic derangements in cachectic mouse muscle tissues were detected, with significantly increased quantities of lysine, arginine, proline, and tyrosine (P = 0.0037, P = 0.0048, P = 0.0430, and P = 0.0357, respectively) and significantly reduced quantities of glutamate and aspartate (P = 0.0008 and P = 0.0124). Human skeletal muscle tissues revealed similar tendencies. A majority of altered amino acids were released by the breakdown of proteins involved in oxidative phosphorylation. Decreased energy charge was observed in cachectic muscle tissues (P = 0.0101), which was related to the breakdown of specific proteins. Additionally, expression of the cationic amino acid transporter CAT1 was significantly decreased in the mitochondria of cachectic mouse muscles (P = 0.0133); this decrease may play an important role in the alterations of cationic amino acid metabolism and decreased quantity of glutamate observed in cachexia.

CONCLUSIONS

Our results suggest that mitochondrial dysfunction has a substantial influence on amino acid metabolism in cachectic skeletal muscles, which appears to be triggered by diminished CAT1 expression, as well as the degradation of mitochondrial proteins. These findings provide new insights into the pathobiochemistry of muscle wasting.

Highly Sensitive Quantification Method for Amine Submetabolome Based on AQC-Labeled-LC-Tandem-MS and Multiple Statistical Data Mining: A Potential Cancer Screening Approach

The relationship between amine submetabolome and cancer has been increasingly investigated. However, no study was performed to evaluate the current methods of amine submetabolomics comprehensively, or to use such quantification results to provide an applicable approach for cancer screening. In this study, a highly sensitive and practical workflow for quantifying amine submetabolome, which was based on 6-aminoquinolyl- N-hydroxysuccinimidyl carbamate (AQC)-labeled-HPLC-MS/MS analysis combined with multiple statistical data processing approach, was established and optimized. Comparison and optimization of two analytical approaches, HILIC separation and precolumn derivatization, and three types of surrogate matrices of plasma were performed systematically. The detection sensitivities of AQC-labeled amines were increased by 50-1000-fold compared with the underivatization-HILIC method. Surrogate matrix was also used to verify the method after a large dilution factor was employed. In data analysis, the specific amino-index for each cancer sample was identified and validated by univariate receiver operating characteristic (ROC) curve analysis, partial least-squares discrimination analysis (PLS-DA), and multivariate ROC curve analysis. These amino indexes were innovatively quantified by multiplying the raised markers and dividing the reduced markers. As a result, the numerical intervals of amino indexes for healthy volunteers and cancer patients were provided, and their clinical value was also improved. Finally, the integrated workflow successfully differentiated the value of the amino index for plasma of lung, breast, colorectal, and gastric cancer samples from controls and among different types of cancer. Furthermore, it was also used to evaluate therapeutic effects. Taken together, the developed methodology, which was characterized by high sensitivity, high throughput, and high practicality, is suitable for amine submetabolomics in studying cancer biomarkers and could also be applied in many other clinical and epidemiological research.

Multiplatform plasma fingerprinting in cancer cachexia: a pilot observational and translational study

BACKGROUND

Cachexia is a metabolic syndrome that affects up to 50-80% of cancer patients. The pathophysiology is characterized by a variable combination of reduced food intake and abnormal metabolism, including systemic inflammation and negative protein and energy balance. Despite its high clinical significance, defined diagnostic criteria and established therapeutic strategies are lacking. The 'omics' technologies provide a global view of biological systems. We hypothesize that blood-based metabolomics might identify findings in cachectic patients that could provide clues to gain knowledge on its pathophysiology, and eventually postulate new therapeutic strategies.

METHODS

This is a cross-sectional observational study in two cohorts of cancer patients, with and without cachexia. Patients were consecutively recruited from routine clinical practice of a General Oncology Department at '12 de Octubre' University Hospital. Selected clinical and biochemical features were collected. Blood metabolite fingerprinting was performed using three analytical platforms, gas chromatography coupled to mass spectrometry (GC-MS), capillary electrophoresis coupled to mass spectrometry (CE-MS), and liquid chromatography coupled to mass spectrometry (LC-MS). Besides, we performed pathway-based metabolite analyses to obtain more information on biological functions.

RESULTS

A total of 15 subjects were included in this study, 8 cachectic and 7 non-cachectic patients. Metabolomic analyses were able to correctly classify their samples in 80% (GC-MS), 97% (CE-MS), 96% [LC-MS (positive mode)], and 89% [LC-MS (negative mode)] of the cases. The most prominent metabolic alteration in plasma of cachectic patients was the decrease of amino acids and derivatives [especially arginine, tryptophan, indolelactic acid, and threonine, with 0.4-fold change (FC) compared with non-cachectic patients], along with the reduction of glycerophospholipids [mainly lysophosphatidylcholines(O-16:0) and lysophosphatidylcholines(20:3) sn-1, FC = 0.1] and sphingolipids [SM(d30:0), FC = 0.5]. The metabolite with the highest increase was cortisol (FC = 1.6). Such alterations suggest a role of the following metabolic pathways in the pathophysiology of cancer cachexia: arginine and proline metabolism; alanine, aspartate, and glutamate metabolism; phenylalanine metabolism; lysine degradation; aminoacyl-tRNA biosynthesis; fatty acid elongation in mitochondria; tricarboxylic acids cycle; among others.

CONCLUSIONS

These findings suggest that plasma amino acids and lipids profiling has great potential to find the mechanisms involved in the pathogenesis of cachexia. Metabolic profiling of plasma from cancer patients show differences between cachexia and non-cachexia in amino acids and lipids that might be related to mechanisms involved in its pathophysiology. A better understanding of these mechanisms might identify novel therapeutic approaches to palliate this unmet medical condition.

Cerebral Gluconeogenesis and Diseases

The gluconeogenesis pathway, which has been known to normally present in the liver, kidney, intestine, or muscle, has four irreversible steps catalyzed by the enzymes: pyruvate carboxylase, phosphoenolpyruvate carboxykinase, fructose 1,6-bisphosphatase, and glucose 6-phosphatase. Studies have also demonstrated evidence that gluconeogenesis exists in brain astrocytes but no convincing data have yet been found in neurons. Astrocytes exhibit significant 6-phosphofructo-2-kinase/fructose-2,6-bisphosphatase-3 activity, a key mechanism for regulating glycolysis and gluconeogenesis. Astrocytes are unique in that they use glycolysis to produce lactate, which is then shuttled into neurons and used as gluconeogenic precursors for reduction. This gluconeogenesis pathway found in astrocytes is becoming more recognized as an important alternative glucose source for neurons, specifically in ischemic stroke and brain tumor. Further studies are needed to discover how the gluconeogenesis pathway is controlled in the brain, which may lead to the development of therapeutic targets to control energy levels and cellular survival in ischemic stroke patients, or inhibit gluconeogenesis in brain tumors to promote malignant cell death and tumor regression. While there are extensive studies on the mechanisms of cerebral glycolysis in ischemic stroke and brain tumors, studies on cerebral gluconeogenesis are limited. Here, we review studies done to date regarding gluconeogenesis to evaluate whether this metabolic pathway is beneficial or detrimental to the brain under these pathological conditions.

Evaluation of Basal Renal Function in Treatment-naïve Patients with Malignancy and Comparison with Age Matched Healthy Control

There is a paucity of data regarding the prevalence of renal insufficiency in patients with malignancy at baseline before initiation of therapy. The published studies based on patient with prior exposure to cytotoxic therapy have reported a high prevalence of renal impairment. However, these studies have utilized creatinine-based glomerular filtration rate (GFR) prediction equations to assess the level of renal function. These equations are known to have some serious limitations in reliably predicting GFR. The aim of the study was to accurately document the state of renal function in treatment-naïve cancer patients and compare them against age-matched healthy controls using a reference "creatinine independent" GFR measurement technique. Age-matched comparison of GFR of 1,373 treatment-naïve cancer patients and 1,089 healthy controls were done retrospectively. There was no difference in GFR between cancer and healthy group when analyzed under various age groups, though the overall mean GFR in healthy controls was significantly higher compared to cancer group (80.14 ± 17.63 mL vs 74.43 ± 20.84, P 0≤ 0.01), whereas the mean age in control arm was significantly lower compared to cancer group (44.24 ± 17.63 years vs. 50.70 ± 20.84 years, P ≤ 0.01). Treatment-naïve cancer patients have identical renal function to their healthy age-matched peers. Malignancy per se does not directly lead to the decline in filtration capacity of the kidneys.

Serum metabolomic profiling facilitates the non-invasive identification of metabolic biomarkers associated with the onset and progression of non-small cell lung cancer

Lung cancer (LC) is responsible for most cancer deaths. One of the main factors contributing to the lethality of this disease is the fact that a large proportion of patients are diagnosed at advanced stages when a clinical intervention is unlikely to succeed. In this study, we evaluated the potential of metabolomics by 1H-NMR to facilitate the identification of accurate and reliable biomarkers to support the early diagnosis and prognosis of non-small cell lung cancer (NSCLC).We found that the metabolic profile of NSCLC patients, compared with healthy individuals, is characterized by statistically significant changes in the concentration of 18 metabolites representing different amino acids, organic acids and alcohols, as well as different lipids and molecules involved in lipid metabolism. Furthermore, the analysis of the differences between the metabolic profiles of NSCLC patients at different stages of the disease revealed the existence of 17 metabolites involved in metabolic changes associated with disease progression.Our results underscore the potential of metabolomics profiling to uncover pathophysiological mechanisms that could be useful to objectively discriminate NSCLC patients from healthy individuals, as well as between different stages of the disease.

Systemic Metabolomic Changes in Blood Samples of Lung Cancer Patients Identified by Gas Chromatography Time-of-Flight Mass Spectrometry

Lung cancer is a leading cause of cancer deaths worldwide. Metabolic alterations in tumor cells coupled with systemic indicators of the host response to tumor development have the potential to yield blood profiles with clinical utility for diagnosis and monitoring of treatment. We report results from two separate studies using gas chromatography time-of-flight mass spectrometry (GC-TOF MS) to profile metabolites in human blood samples that significantly differ from non-small cell lung cancer (NSCLC) adenocarcinoma and other lung cancer cases. Metabolomic analysis of blood samples from the two studies yielded a total of 437 metabolites, of which 148 were identified as known compounds and 289 identified as unknown compounds. Differential analysis identified 15 known metabolites in one study and 18 in a second study that were statistically different (p-values <0.05). Levels of maltose, palmitic acid, glycerol, ethanolamine, glutamic acid, and lactic acid were increased in cancer samples while amino acids tryptophan, lysine and histidine decreased. Many of the metabolites were found to be significantly different in both studies, suggesting that metabolomics appears to be robust enough to find systemic changes from lung cancer, thus showing the potential of this type of analysis for lung cancer detection.

Gain of glucose-independent growth upon metastasis of breast cancer cells to the brain

Breast cancer brain metastasis is resistant to therapy and a particularly poor prognostic feature in patient survival. Altered metabolism is a common feature of cancer cells, but little is known as to what metabolic changes benefit breast cancer brain metastases. We found that brain metastatic breast cancer cells evolved the ability to survive and proliferate independent of glucose due to enhanced gluconeogenesis and oxidations of glutamine and branched chain amino acids, which together sustain the nonoxidative pentose pathway for purine synthesis. Silencing expression of fructose-1,6-bisphosphatases (FBP) in brain metastatic cells reduced their viability and improved the survival of metastasis-bearing immunocompetent hosts. Clinically, we showed that brain metastases from human breast cancer patients expressed higher levels of FBP and glycogen than the corresponding primary tumors. Together, our findings identify a critical metabolic condition required to sustain brain metastasis and suggest that targeting gluconeogenesis may help eradicate this deadly feature in advanced breast cancer patients.

Amino acid profile index for early detection of endometrial cancer: verification as a novel diagnostic marker

BACKGROUND

Plasma amino acid profiles (PAAPs) vary in individual cancer patients, and it has been suggested that they may be useful for early detection of several types of cancer. We evaluated the diagnostic performance of a profile index for endometrial cancer composed of multiple plasma amino acids as a novel biomarker and compared its diagnostic performance with that of CA125.

METHODS

Plasma amino acid levels of 80 patients with endometrial cancer, 122 with benign gynecological diseases, and 240 age- and body mass index-matched control subjects were measured using liquid chromatography and mass spectrometry. After univariate analysis, we applied a multiplex model based on the PAAP multivariate analysis to distinguish patients with endometrial cancer from control subjects. We compared the diagnostic performance of the multiple PAAP index (API) with that of CA125.

RESULTS

The levels of several plasma amino acids were significantly different in patients with endometrial cancer. The area under the receiver operating characteristic curves (AUC) used to distinguish endometrial cancer patients from control subjects was 0.94. The AUC for API was significantly larger than that for CA125 (P = 0.0068). For the same specificity of 98.3 %, API showed a significantly higher sensitivity (60.0 %, 95 % CI, 43.3-75.1) than that of CA125 (22.5 %, 95 % CI, 10.1-38.5). In stage I cases, API showed significantly higher positivity than that of CA125 (P = 0.0002).

CONCLUSIONS

The sensitivity and disease specificity of API for early-stage detection of endometrial cancer was superior to CA125. This novel plasma biomarker has the potential to become a diagnostic and screening marker for endometrial cancer.

Reversal by growth hormone of homocysteine-induced epithelial-to-mesenchymal transition through membrane raft-redox signaling in podocytes

Epithelial-to-Mesenchymal Transition (EMT) is an important pathogenic mechanism mediating glomerular injury or sclerosis in a variety of renal and systemic diseases such as hyperhomocysteinemia (hHcys). The present study was designed to test whether Hcys-induced EMT in podocytes is reversed by growth hormone (GH), a hormone regulating cell differentiation and growth and to explore the cellular and molecular mechanism mediating its action. It was found that Hcys induced significant EMT in podocytes, as shown by marked decreases in slit diaphragm-associated protein P-cadherin and zonula occludens-1 as epithelial markers and by dramatic increases in the expression of mesenchymal markers, fibroblast specific protein-1 and α-smooth muscle actin, which were detected by all examinations via immunocytochemistry, real time RT-PCR and Western blot analysis. When podocytes were treated with GH at 25 ng/mL, however, Hcys failed to induce podocyte EMT. Using electromagnetic spin resonance spectrometry, Hcys-induced superoxide (O(2).(-)) production via NADPH oxidase was found to be significantly inhibited by GH (66%). Functionally, GH was shown to substantially inhibit Hcys-induced increases in the permeability of podocyte monolayers and to block the decrease in podocin expression in these cells. In addition, NADPH oxidase subunit, gp91(phox) and GH receptors aggregated in membrane raft clusters, which produced O(2).(-) in response to Hcys and could be blocked by GH, membrane raft disruptors filipin and MCD or NADPH oxidase inhibitor, apocynin. It is concluded that Hcys-induced podocyte EMT is associated with transmembrane membrane raft-redox signaling and that GH reverses this Hcys-induced EMT protecting podocytes from functional disturbance.

The cachexia score (CASCO): a new tool for staging cachectic cancer patients

BACKGROUND: According to a recent consensus, the cachectic syndrome is defined as: "… a complex metabolic syndrome associated with underlying illness and characterized by loss of muscle with or without loss of fat mass. The prominent clinical feature of cachexia is weight loss in adults (corrected for fluid retention) or growth failure in children (excluding endocrine disorders). Anorexia, inflammation, insulin resistance, and increased muscle protein breakdown are frequently associated with cachexia." Although this definition is accompanied by diagnostic criteria, it does not consider the problem of staging. Stratification of patients is important when considering therapy. The very first stage of the wasting syndrome does not necessarily involve body weight loss-a state known as pre-cachexia. METHODS AND RESULTS: The aim of the present score was to overcome the problem of patient staging in cancer. This score considers five main different factors: body weight and lean body mass loss; anorexia; inflammatory, immunological, and metabolic disturbances; physical performance; and quality of life. The scoring scale goes from 0 to 100: mild cachexia (less than 25), moderate (more than 26 and less than 50), severe (more than 51 and less than 75), and terminal phase (more than 76 and up to 100). The score also takes into consideration the condition known as pre-cachexia. CONCLUSION: The present score will facilitate cachexia staging and will therefore allow for a more adequate therapy. ELECTRONIC SUPPLEMENTARY MATERIAL: The online version of this article (doi:10.1007/s13539-011-0027-5) contains supplementary material, which is available to authorized users.

Early supplementation of parenteral nutrition is capable of improving quality of life, chemotherapy-related toxicity and body composition in patients with advanced colorectal carcinoma undergoing palliative treatment: results from a prospective, randomized clinical trial

AIM

Patients suffering from advanced colorectal cancer can experience unintended weight loss and/or treatment-induced gastrointestinal toxicity. Based on current evidence, the routine use of parenteral nutrition (PN) for patients with colorectal cancer is not recommended. This study evaluates the effect of PN supplementation on body composition, quality of life (QoL), chemotherapy-associated side effects and survival in patients with advanced colorectal cancer.

METHOD

Eighty-two patients with advanced colorectal cancer receiving a palliative chemotherapy were prospectively randomized to either oral enteral nutrition supplement (PN-) or oral enteral nutrition supplement plus supplemental PN (PN+). Every 6 weeks body weight, body mass index (BMI), chemotherapy-associated side effects and caloric intake were assessed, haemoglobin and serum albumin were measured. Body composition was assessed by body impedance analysis, and QoL was evaluated by European Organization for Research and Treatment of Cancer (EORTC) QLQC30 questionnaire.

RESULTS

No differences were evident at baseline between the groups for age, sex, diagnosis, weight, BMI or QoL. A difference in BMI was observed by week 36, whereas differences of the mean body cell mass could be observed from week 6, albumin dropped significantly in the PN- group in week 36 and QoL showed significant differences from week 18. Chemotherapy-associated side effects were higher in PN-. The survival rate was significantly greater in the PN+ group.

CONCLUSION

A supplementation with PN slows weight loss, stabilizes body-composition and improves QoL in patients with advanced colorectal cancer. Furthermore, it can reduce chemotherapy-related side effects.

Central mechanisms controlling appetite and food intake in a cancer setting: an update

PURPOSE OF REVIEW

Cachexia, also known as disease-associated wasting, is an important factor in the mortality of many patients with diseases such as cancer, as well as renal and congestive heart failure. Yet the syndrome is not yet well defined, making diagnosis difficult and often subjective on the part of the physician. Nor are the central mechanisms of cachexia fully elucidated. Recent studies have begun to address these gaps by focusing on three areas: the role of cytokines in cachexia, other proteins and peptides that might be involved, and potential treatments for this devastating syndrome.

RECENT FINDINGS

Cachexia can be caused, in the absence of disease, by inflammatory stimuli and some chemotherapy drugs, suggesting possible central mechanisms in cachexia. Promising treatments include melanocortin antagonism and some hormones.

SUMMARY

While more research is necessary to illuminate causal mechanisms and uncover potential therapies of cachexia, several of its major molecular pathways have become elucidated, suggesting directions for therapeutic approaches.

Antioxidative activity of amino acids on tissue oxidative stress in human intestinal epithelial cell model

The protective effects of amino acids against H 2O 2-induced oxidative stress were investigated in an in vitro assay using human intestinal epithelial cells. Caco-2 cells were pretreated with amino acids (1, 2, and 5 mM) for 2 h and then stimulated with 1 mM H 2O 2 for 6 h. The secretion of IL-8, a proinflammatory mediator, was determined by ELISA as an indicator of tissue oxidative stress. The inhibition of H 2O 2-induced IL-8 secretion from Caco-2 cells was observed by pretreatment with Cys, Val, Ile, Leu, Trp, His, Lys, and Ala. Cys enhanced glutathione (GSH) biosynthesis enzyme activity and increased cellular GSH levels. Branched-chain amino acids such as Val, Ile, and Leu elevated activities of GSH S-transferase (GST) and catalase. Trp, His, and Lys caused increases in GST activity. Ala enhanced GSH reductase activity. These data suggest that specific amino acids exert protective effects against tissue oxidative stress in intestinal epithelial cells based on the structure.

The influence of early supplementation of parenteral nutrition on quality of life and body composition in patients with advanced cancer

BACKGROUND

According to current evidence, most organizations, including the American Society for Parenteral and Enteral Nutrition (A.S.P.E.N.), do not recommend the routine use of artificial nutrition for patients with cancer. Despite the recommendation for parenteral nutrition (PN), data for early PN supplementation (PNS) in patients with an advanced malignancy are extremely limited, especially in terms of the affects on nutrition outcomes, body composition, and quality of life (QOL), as well as effects on oncologic outcomes. The aim of the study was to evaluate the effect of PNS on body composition and the quality of life in patients with advanced malignancies.

METHODS

One hundred fifty-two consecutive patients with advanced cancer were prospectively randomized to either use of oral enteral nutrition supplement (PN-) or use of oral enteral nutrition supplement plus supplemental PN (PN+). Body weight, body mass index (BMI), and caloric intake were assessed, and hemoglobin (g/dL) and serum albumin (g/L) were measured. Body composition was assessed by body impedance analysis (BIA), and QOL was evaluated by European Organization for Research and Treatment of Cancer (EORTC) QLQ-C30 questionnaire every 6 weeks.

RESULTS

No significant differences were evident at baseline between the 2 groups for age, gender, medical diagnosis, weight, BMI, or QOL. A statistically significant difference in mean BMI was observed by week 48 for the PN+ group (PN+ = 21.9, PN-= 20.5, p = .0149), by week 6 in mean body cell mass (PN+ = 55%, PN-= 50,1%, p < .001), mean albumin (PN+ = 40.2 g/L, PN-= 36.2 g/L, p = .015), mean QOL (PN+ = 55.7, PN-= 50.9, p = .035). The cumulative survival rate was significantly greater in the PN+ group (p < .0001).

CONCLUSIONS

According to the positive effect of supplemental PN on survival, body composition, and QOL, additional controlled studies must be conducted to confirm these findings.

Redox regulation in anabolic and catabolic processes

PURPOSE OF REVIEW

Muscle wasting as it typically occurs in old age and in certain diseases is poorly understood. This review summarizes recent findings suggesting a role for redox-sensitive signaling cascades in catabolic processes.

RECENT FINDINGS

The redox-sensitive transcription factors nuclear factor kappaB and activator protein 1 facilitate ubiquitin-proteasome-dependent proteolysis. Nuclear factor kappaB also plays a role in induced expression of tumor necrosis factor alpha and other inflammatory cytokines that have been implicated in catabolic processes. The activities of nuclear factor kappaB and activator protein 1 are stimulated not only by hydrogen peroxide, which is produced in tissues by regulated enzymatic processes, but also by an oxidative shift in thiol-disulfide redox status. The oxidative shift that is typically seen in old age and certain catabolic conditions may thus play a causative role in catabolic processes. Another prominent case in point is insulin-independent 'basal' insulin receptor kinase activity, which is strongly enhanced by hydrogen peroxide or by an oxidative shift in redox status. The insulin receptor signaling cascade induces anabolic and anticatabolic effects, but its abnormal upregulation under starving conditions potentially compromises glucose and amino acid homeostasis. In genetic animal studies, impairment of insulin receptor signaling was shown to increase life span.

SUMMARY

These findings may provide a rationale for cysteine supplementation in catabolic conditions.

Plasma free amino acid profile in cancer patients

Redistribution or translocation of plasma free amino acids (PFAAs) to support visceral or tumor protein synthesis is an essential feature in cancer patients. An abnormal PFAA profile might be presented via the total reflection of cancer-induced protein metabolism in tumors, skeletal muscle and the liver in cancer patients. Clinical data from 13 studies have demonstrated a cancer-related PFAA profile, especially in digestive organ cancers. The PFAA profile can differ between the early and late stages of cancer. The profile is also affected by the type of cancer. Therefore, it is postulated that a detailed analysis of the PFAA profile may serve as one of the biological markers for cancer patients.

Metabolic and hematological effects of dietary supplementation with arginine on rats bearing ascitic Walker 256 tumor

The notion of using supplementary quantities of arginine for nutritional support in patients with cancer has been evaluated not only as supplement intake of nitrogen substrate but also for its immunopharmacological effects capable of improving the patient's prognosis. The aim of the present study is to evaluate the effects of dietary supplementation with arginine on metastatic dissemination, amino acid metabolism, hematological functions of rats with Walker 256 ascitic tumor. Animals were inoculated intraperitoneally with approximately 4 million cells. Nutritional solutions containing 4 or 6% arginine or just a control diet without added arginine, were administered to the animals via esophagic gavages. The rate of metastasis was lower in animals supplemented with arginine at 4 and 6%. Amino acid metabolism was stimulated in tumor-bearing animals after receiving 4 or 6% arginine, demonstrated by significant increase of arginine, ornithine, citrulline, proline and histidine levels in the blood (p < or = 0.001) when compared to the control diet group. Anemia was less severe in tumor-bearing animals that received arginine supplementation. The findings suggest that arginine supplementation at 6% may have a beneficial effect on to the host, besides its pharmacological action.

Coordinate upregulation of proteolytic-related genes in rat muscle during late fasting

The present study examines whether and to what extent the profiles of proteolytic-related genes are altered in atrophying muscle during prolonged food deprivation. Long-term fasted animals exhibited three metabolic phases characterized by changes in lipid and protein utilization. Starvation induced an increase in some proteolytic gene expressions during P2 of fasting, especially for Cat L (by 3-fold). In P3, the fasting-induced enhancement of mRNA expression involved all proteolytic pathways and was much more pronounced than in P2 for pUb, E2(14k), CAPN3, and Cat B, D, and H (by 2- to 4-fold), for C2, C5, and S5a (by 5- to 6-fold), and mainly for Cat L, C3, and C8 (by 10- to 15-fold). At the molecular level, it is concluded that the three proteolytic systems found in skeletal muscle are selectively induced in P2 of fasting and coordinately upregulated in late fasting.

Reversal of cancer-related wasting using oral supplementation with a combination of beta-hydroxy-beta-methylbutyrate, arginine, and glutamine

BACKGROUND

Cancer-related cachexia is caused by a diverse combination of accelerated protein breakdown and slowed protein synthesis. The hypothesis proposed in this study is that supplementation of specific nutrients known to positively support protein synthesis and reduce protein breakdown will reverse the cachexia process in advanced cancer patients.

METHODS

Patients with solid tumors who had demonstrated a weight loss of at least 5% were considered for the study. Patients were randomly assigned in a double-blind fashion to either an isonitrogenous control mixture of nonessential amino acids or an experimental treatment containing beta-hydroxy-beta-methylbutyrate (3 g/d), L-arginine (14 g/d), and L-glutamine (14 g/d [HMB/Arg/Gln]). The primary outcomes measured were the change in body mass and fat-free mass (FFM), which were assessed at 0, 4, 8, 12, 16, 20, and 24 weeks.

RESULTS

Thirty-two patients (14 control, 18 HMB/Arg/Gln) were evaluated at the 4-week visit. The patients supplemented with HMB/Arg/Gln gained 0.95 +/- 0.66 kg of body mass in 4 weeks, whereas control subjects lost 0.26 +/- 0.78 kg during the same time period. This gain was the result of a significant increase in FFM in the HMB/Arg/Gln-supplemented group (1.12 +/- 0.68 kg), whereas the subjects supplemented with the control lost 1.34 +/- 0.78 kg of FFM (P = 0.02). The response to 24-weeks of supplementation was evaluated by an intent-to-treat statistical analysis. The effect of HMB/Arg/Gln on FFM increase was maintained over the 24 weeks (1.60 +/- 0.98 kg; quadratic contrast over time, P <0.05). There was no negative effect of treatment on the incidence of adverse effects or quality of life measures.

CONCLUSIONS

The mixture of HMB/Arg/Gln was effective in increasing FFM of advanced (stage IV) cancer. The exact reasons for this improvement will require further investigation, but could be attributed to the observed effects of HMB on slowing rates of protein breakdown, with improvements in protein synthesis observed with arginine and glutamine.

Amino acid deprivation induces translation of branched-chain alpha-ketoacid dehydrogenase kinase

Leucine, isoleucine, and valine are used by cells for protein synthesis or are catabolized into sources for glucose and lipid production. These branched-chain amino acids influence proteolysis, hormone release, and cell cycle progression along with their other metabolic roles. The branched-chain amino acids play a central role in regulating cellular protein turnover by reducing autophagy. These essential amino acids are committed to their catabolic fate by the activity of the branched-chain alpha-ketoacid dehydrogenase complex. Activity of the branched-chain alpha-ketoacid dehydrogenase complex is regulated by phosphorylation/inactivation of the alpha-subunit performed by a complex specific kinase. Here we show that elimination of the branched-chain amino acids from the medium of cultured cells results in a two- to threefold increased production of the branched-chain alpha-ketoacid dehydrogenase kinase with a decrease in the activity state of the branched-chain alpha-ketoacid dehydrogenase complex. The mechanism cells use to increase kinase production under these conditions involves recruitment of the kinase mRNA into polyribosomes. Promoter activity and the steady-state concentration of the mRNA are unchanged by these conditions.

Controlled overexpression of BCKD kinase expression: metabolic engineering applied to BCAA metabolism in a mammalian system

A common metabolic complication of human disease is uncontrolled muscle protein breakdown or cachexia, which occurs in patients with chronic diseases such as cancer, AIDS, renal failure, and diabetes. Increased branched-chain amino acid catabolism is implicated as causal and has stimulated the investigation of methods to regulate the metabolism of these amino acids. Here we demonstrate doxycycline-controlled overexpression of a branched-chain alpha-ketoacid dehydrogenase (BCKD) kinase transgene in mammalian cell culture. This kinase functions to inactivate the BCKD complex by phosphorylation, thus preventing the catabolism of these essential, regulatory metabolites. In this study, doxycycline treatment leads to a 10-fold increase in BCKD kinase protein. The transgene-generated kinase is rapidly incorporated within mitochondria and functions correctly to inactivate the BCKD complex. The maximum reduction in basal BCKD activity achieved was 94%. Unexpectedly, total BCKD activity was also decreased by kinase overexpression despite no observable change in expression of the BCKD catalytic proteins. These results demonstrate that artificial regulation of branched-chain amino acid metabolism is possible through the controlled overexpression of a single endogenous enzyme and suggest the feasibility of clinical applications.

NF-kappaB mediates the protein loss induced by TNF-alpha in differentiated skeletal muscle myotubes

Nuclear factor-kappaB (NF-kappaB) regulates the transcription of a variety of genes involved in immune responses, cell growth, and cell death. However, the role of NF-kappaB in muscle biology is poorly understood. We recently reported that tumor necrosis factor-alpha (TNF-alpha) rapidly activates NF-kappaB in differentiated skeletal muscle myotubes and that TNF-alpha acts directly on the muscle cell to induce protein degradation. In the present study, we ask whether NF-kappaB mediates the protein loss induced by TNF-alpha. We addressed this problem by creating stable, transdominant negative muscle cell lines. C2C12 myoblasts were transfected with viral plasmid constructs that induce overexpression of mutant I-kappaBalpha proteins that are insensitive to degradation via the ubiquitin-proteasome pathway. These mutant proteins selectively inhibit NF-kappaB activation. We found that differentiated myotubes transfected with the empty viral vector (controls) underwent a drop in total protein content and in fast-type myosin heavy-chain content during 72 h of exposure to TNF-alpha. In contrast, total protein and fast-type myosin heavy-chain levels were unaltered by TNF-alpha in the transdominant negative cell lines. TNF-alpha did not induce apoptosis in any cell line, as assessed by DNA ladder and annexin V assays. These data indicate that NF-kappaB is an essential mediator of TNF-alpha-induced catabolism in differentiated muscle cells.

Pathophysiology of cancer cachexia

Cancer cachexia is a frequent complication observed in patients with malignant tumors. Although several decades have passed since the first focus on the metabolic dysfunction's associated with cancer, few effective therapeutic interventions have been successfully introduced into the medical armamentarium. The present study thoroughly reviews the basic pathophysiology of cancer cachexia and the treatment options already investigated in that field. Experimental and clinical studies were evaluated individually in order to clarify the intricate alterations observed in tumor-bearing patients. The difficulties in introducing sound and effective nutritional support or metabolic manipulation to reverse cancer cachexia are outlined in this review.

Beta-hydroxy-beta-methylbutyrate (HMB) supplementation and the promotion of muscle growth and strength

Beta-hydroxy beta-methylbutyrate (HMB), a metabolite of the essential amino acid leucine, is one of the latest dietary supplements promoted to enhance gains in strength and lean body mass associated with resistance training. Unlike anabolic hormones that induce muscle hypertrophy by increasing muscle protein synthesis, HMB is claimed to influence strength and lean body mass by acting as an anticatabolic agent, minimising protein breakdown and damage to cells that may occur with intense exercise. Research on HMB has recently tested this hypothesis, under the assumption that it may be the active compound associated with the anticatabolic effects of leucine and its metabolites. While much of the available literature is preliminary in nature and not without methodological concern, there is support for the claims made regarding HMB supplementation, at least in young, previously untrained individuals. A mechanism by which this may occur is unknown, but research undertaken to date suggests there may be a reduction in skeletal muscle damage, although this has not been assessed directly. The response of resistance trained and older individuals to HMB administration is less clear. While the results of research conducted to date appear encouraging, caution must be taken when interpreting outcomes as most manuscripts are presented in abstract form only, not having to withstand the rigors of peer review. Of the literature reviewed relating to HMB administration during resistance training, only 2 papers are full manuscripts appearing in peer reviewed journals. The remaining 8 papers are published as abstracts only, making it difficult to critically review the research. There is clearly a need for more tightly controlled, longer duration studies to verify if HMB enhances strength and muscular hypertrophy development associated with resistance training across a range of groups, including resistance trained individuals.

Nutritional support of the cancer patient: issues and dilemmas

Malnutrition in cancer patients results from multifactorial events and is associated with an alteration of quality of life and a reduced survival. A simple nutritional assessment program and early counselling by a dietitian are essential to guide nutritional support and to alert the physician to the need for enteral (EN) or parenteral nutrition (PN). A daily intake of 20-35 kcal/kg, with a balanced contribution of glucose and lipids, and of 0.2-0.35 g nitrogen/kg is recommended both for EN and PN, with an adequate provision of electrolytes, trace elements and vitamins. EN, always preferable for patients with an intact digestive tract, and PN are both safe and effective methods of administering nutrients. The general results in clinical practice suggest no tumor growth during nutritional support. The indiscriminate use of conventional EN and PN is not indicated in well-nourished cancer patients or in patients with mild malnutrition. EN or PN is not clinically efficacious for patients treated with chemotherapy or radiotherapy, unless there are prolonged periods of GI toxicity, as in the case of bone marrow transplant patients. Severely malnourished cancer patients undergoing major visceral surgery may benefit from perioperative nutritional support, preferably via enteral access. Nutritional support in palliative care should be based on the potential risks and benefits of EN and PN, and on the patient's and family's wishes. Research is currently directed toward the impact of nutritional pharmacology on the clinical outcome of cancer patients. Glutamine-supplemented PN is probably beneficial in bone marrow transplant patients. Immune diets are likely to reduce the rate of infectious complications and the length of hospital stay after GI surgery. Further studies are needed to determine the efficacy of such novel approaches in specific populations of cancer patients, and should also address the question of the overall cost-benefit ratio of nutritional pharmacology, and the effect of nutritional support on length and quality of life.

Effect of carnitine on muscular glutamate uptake and intramuscular glutathione in malignant diseases

Abnormally low intramuscular glutamate and glutathione (GSH) levels and/or a decreased muscular uptake of glutamate by the skeletal muscle tissue have previously been found in malignant diseases and simian immunodeficiency virus (SIV) infection and may contribute to the development of cachexia. We tested the hypothesis that an impaired mitochondrial energy metabolism may compromise the Na+-dependent glutamate transport. A randomized double-blind clinical trial was designed to study the effects of L-carnitine, i.e. an agent known to enhance mitochondrial integrity and function, on the glutamate transport and plasma glutamate level of cancer patients. The effect of carnitine on the intramuscular glutamate and GSH levels was examined in complementary experiments with tumour-bearing mice. In the mice, L-carnitine treatment ameliorated indeed the tumour-induced decrease in muscular glutamate and GSH levels and the increase in plasma glutamate levels. The carnitine-treated group in the randomized clinical study showed also a significant decrease in the plasma glutamate levels but only a moderate and statistically not significant increase in the relative glutamate uptake in the lower extremities. Further studies may be warranted to determine the effect of L-carnitine on the intramuscular GSH levels in cancer patients.

A new model of cancer cachexia: contribution of the ubiquitin-proteasome pathway

A new model of cachexia is described in which muscle protein metabolism related to the ubiquitin-proteasome pathway was investigated. Cloning of the colon-26 tumor produced a cell line, termed R-1, which induced cytokine (noninterleukin-1beta, interleukin-6 and tumor necrosis factor-alpha)-independent cachexia. Implantation of R-1 cells in mice elicited significant (20-30%) weight loss and decreased blood glucose by 70%, and adipose tissue levels declined by 95% and muscle weights decreased by 20-25%. Food intake was unaffected. The decrease in muscle weight reflected a decline in insoluble, but not soluble, muscle protein that was associated with a significant increase in net protein degradation. The rate of ubiquitin conjugation of proteins was significantly elevated in muscles of cachectic mice. Furthermore, the proteasome inhibitor lactacystin blocked the increase in protein breakdown but had no significant effect on proteolysis. Several markers of the ubiquitin-proteasome pathway, E2(14k) mRNA and E2(14k) protein and ubiquitin-protein conjugates, were not elevated. Future investigations with this new model should gain further insights into the mechanisms of cachexia and provide a background to evaluate novel and more efficacious therapies.

Ongoing assessment of nutritional status in children with malignant disease

The nutritional status of a child on cancer therapy influences both tolerance of and response to treatment. However, it is difficult to assess nutritional status on a daily basis because an accurate quantitation of the calorie intake is difficult. Anthropometric and biochemical parameters are prone to error and often reflect past rather than current nutritional status. In practice, a subjective clinical assessment is usually relied upon. This study objectively appraises the value of such an assessment. Based on clinical symptoms that alter oral intake and absorption of food, a scoring system was designed to assess nutritional status on a day to day basis. A symptom score (SS) of 10 implied "normality"; 0 indicated maximum debility. Over a 2-year period 511 daily scores were recorded in 30 patients aged 0.7-17.5 years. Patients were studied at presentation and during treatment for acute lymphoblastic leukemia (ALL, n = 14; solid tumors receiving megatherapy with autologous bone marrow rescue (ABMR, n = 8), and chemotherapy for different tumors (miscellaneous, n = 8). The SS was compared with other nutritional parameters, including sequential anthropometric indices, serum albumin, insulin-like growth factor-I (IGF-I), IGF binding protein-3 (IGFBP-3), and whole-body protein turnover (WBPT) using [1-(13) C]leucine. The mean SS was reduced at diagnosis for all leukemic patients (median score = 8), improved during first remission (p < 0.002), fell to a minimum during febrile neutropenia (p = 0.0009), and improved with clinical and hematological recovery (p = 0.0009). A reduction in SS was related to fever (p < 0.001) and a fall in neutrophil count (p < 0.001). There was no correlation with anthropometric indices or IGF-I and IGFBP-3 levels. Paired WBPT studies in 9 patients showed that SS correlated well with protein breakdown (p = 0.026). The results suggest that the ongoing nutritional status of children with malignancy undergoing chemotherapy is best assessed using simple clinical parameters.

The Redox State as a Correlate of Senescence and Wasting and as a Target for Therapeutic Intervention

The loss of body cell mass (bcm) in senescence and wasting is poorly understood. We now show that the plasma cystine/acid soluble thiol ratio, ie, an indicator of the redox state, is increased in old age and cancer patients and correlated with a decrease in bcm and plasma albumin. A cause/effect relationship was suggested by two independent studies with N-acetyl-cysteine (NAC). NAC caused an increase in the bcm of healthy persons with high plasma cystine/thiol ratios, and treatment of cancer patients with NAC plus interleukin-2 caused an increase in bcm, plasma albumin, and functional capacity. Albumin levels below 680 μmol/L were associated with an increase in body water. Our studies suggest that the shift in the redox state may contribute to the loss of bcm and may provide a quantitative guideline for therapeutic intervention. Treatment of cancer patients with thiol-containing antioxidants may improve the quality of life.

In vivo inter-organ protein metabolism of the splanchnic region and muscle during trauma, cancer and enteral nutrition

The study of protein kinetics has entered a new era by the recognition that whole body protein turnover only poorly reflects the true events occurring in several organs and with regard to the multitude of proteins present in the body. It is also increasingly recognized that the simultaneous synthesis and degradation of proteins is important in regulation and adaptation during several metabolic conditions like starvation, feeding, after trauma, and during exercise. Especially important is the recognition that the kinetics of individual proteins may change in opposite directions, thereby leading to fluxes of alpha-amino-nitrogen that serve to adapt to and survive a changing environment. At present, much emphasis is put upon molecular biological regulation. However, it is important that the metabolic processes that occur in the intact organism are still poorly defined. New technology allows the exploration of these processes, which should therefore prompt the initiation of further research in this area.