The significance of urinary beta-aminoisobutyric acid in cancer patients

Signaling metabolite β-aminoisobutyric acid as a metabolic regulator, biomarker, and potential exercise pill

Signaling metabolites can effectively regulate the biological functions of many tissues and organs. β-Aminoisobutyric acid (BAIBA), a product of valine and thymine catabolism in skeletal muscle, has been reported to participate in the regulation of lipid, glucose, and bone metabolism, as well as in inflammation and oxidative stress. BAIBA is produced during exercise and is involved in the exercise response. No side effect has been observed in human and rat studies, suggesting that BAIBA can be developed as a pill that confers the benefits of exercise to subjects who, for some reason, are unable to do so. Further, BAIBA has been confirmed to participate in the diagnosis and prevention of diseases as an important biological marker of disease. The current review aimed to discuss the roles of BAIBA in multiple physiological processes and the possible pathways of its action, and assess the progress toward the development of BAIBA as an exercise mimic and biomarker with relevance to multiple disease states, in order to provide new ideas and strategies for basic research and disease prevention in related fields.

In-Vivo Degradation of DNA-Based Therapeutic BC 007 in Humans

BACKGROUND AND OBJECTIVES

Since there is no clear evidence in the literature to show how non-modified single-stranded DNA (ssDNA) drugs are metabolized in humans, we assessed the metabolism of BC 007, an ssDNA therapeutic, under development as a neutralizer of autoantibodies against G-protein-coupled receptors. In-vitro, investigating its stability in monkey plasma and serum, a successive 3'-exonuclease degradation resulting in several n-x degradation products has been previously reported. Here, we investigated the metabolism of BC 007 in humans after intravenous application to autoantibody-positive healthy subjects, in line with Phase I safety testing.

METHODS

¹H-NMR was applied for n-x degradation product search and beta-aminoisobutyric acid (bAIBA) measurement in urine; ultra-performance liquid chromatography-mass spectrometry was also used for the latter. Colorimetric assays were used for quantification of uric acid in serum and urine.

RESULTS

Fast degradation prohibited the detection of the intermediate n-x degradation products in urine using ¹H-NMR. Instead, NMR revealed a further downstream degradation product, bAIBA, which was also detected in serum shortly after initial application. The purine degradation product, uric acid, confirmed this finding of fast metabolism.

CONCLUSION

Fast and full degradation of BC 007, shown by nucleic bases degradation products, is one of the first reports about the fate of a ssDNA product in humans.

Identification of physiologically active substances as novel ligands for MRGPRD

Mas-related G-protein coupled receptor member D (MRGPRD) is a G protein-coupled receptor (GPCR) which belongs to the Mas-related GPCRs expressed in the dorsal root ganglia (DRG). In this study, we investigated two novel ligands in addition to beta-alanine: (1) beta-aminoisobutyric acid, a physiologically active substance, with which possible relation to tumors has been seen together with beta-alanine; (2) diethylstilbestrol, a synthetic estrogen hormone. In addition to the novel ligands, we found that transfection of MRGPRD leads fibroblast cells to form spheroids, which would be related to oncogenicity. To understand the MRGPRD novel character, oncogenicity, a large chemical library was screened in order to obtain MRGPRD antagonists to utilize in exploring the character. The antagonist in turn inhibited the spheroid proliferation that is dependent on MRGPRD signaling as well as MRGPRD signals activated by beta-alanine. The antagonist, a small-molecule compound we found in this study, is a potential anticancer agent.

beta-Aminoisobutyric acid as a marker of thymine catabolism in malignancy

Urine from untreated patients with various tumours and controls has been examined for the excretion of beta-aminoisobutyric acid and uric acid. The patients were classified into four groups: I, beta-aminoisobutyric acid and uric acid both normal; II, beta-aminoisobutyric acid normal, uric acid elevated; III, beta-aminoisobutyric acid elevated, uric acid normal; IV, beta-aminoisobutyric acid and uric acid both elevated. Uric acid was used as an indicator for tissue-breakdown. Pseudouridine being a specific parameter for t-RNA degradation was estimated for comparison. Increased urinary concentrations of beta-aminoisobutyric acid were frequently found in tumour patients, especially in patients with leukaemia and non-Hodgkin lymphoma. Tissue breakdown being the cause of the beta-aminoisobutyric aciduria could only be considered in part of the patients. Moreover, strongly elevated ratios of beta-aminoisobutyric acid to uric acid were found. Urinary patterns of pyrimidines and purines were determined in order to exclude other abnormalities. The results are discussed in relation to thymine metabolism and renal function.

Infrequency of urinary excretion of beta-aminoisobutyric acid by healthy humans

Urinary beta-aminoisobutyric acid (BAIB) levels were measured by modified ion-exchange chromatography. Daily BAIB levels are reported for a group of apparently healthy individuals, a subject with infective hepatitis and two human genetic variants who were high "excretors" of BAIB. The frequency of high "excretors" of BAIB was found using low-voltage paper electrophoresis. The frequency among 403 male European subjects was 5 (1.2%) and lower than previous estimates in the United Kingdom. The percentage recovery of fed BAIB suggests that Oriental "excretors" may have a different type of genetic lesion from non-Oriental "excretors". The clinical usefulness of urinary BAIB assays and qualitative screening is reviewed.

Urinary amino acid excretion by patients with beta-thalassemia

Twenty-four hour urinary amino acid excretion has been studied in patients with beta-thalassemia (four adult major, two adult intermedia, and three children major). beta-Aminoisobutyric acid was found to be increased (14-fold on the average) in patients with beta-thalassemia without evidence for increase in the excretion of most other amino acids. No correlation of beta-aminoisobutyric acid excretion with the hematological status of the patient was found. Elevated taurine excretion (2-fold) was also noted in the adult patients with beta-thalassemia. Greatly increased excretion of beta-aminoisobutyric acid appears to correlate with a poor prognosis and may reflect generalized tissue catabolism rather than being a specific indicator of ineffective erythropoiesis.