Monoclonal Antibody Functionalized, and L-lysine α-Oxidase Loaded PEGylated-Chitosan Nanoparticle for HER2/Neu Targeted Breast Cancer Therapy

Simple Summary

Breast cancer is one of the dominant cancers that threaten human beings worldwide. Moreover, the treatment of HER2+ breast cancer is challenging due to heterogeneity. The L-lysine α-oxidase (LO) enzyme is a well-known antitumor enzyme, but its clinical utility has been limited due to side effects, decreased stability, and inability to target tumor cells. To overcome the clinical challenges in delivery of LO enzymes and improve HER2+ breast cancer therapeutics, the present study developed the dual stimuli responsive nanocarrier system (CS-LO-PEG-HER NPs) for pH sensitive and HER2/neu targeted breast cancer therapy.

Abstract

Herein, we designed a nanocarrier to deliver the LO specifically to HER2+ breast cancer (BC) cells, where functionalization of mAb (anti-HER2+) with PEGylated chitosan enabled it to target the HER2+ BC cells. Taking advantage of overexpression of HER2+ in cancer cells, our nanocarrier (CS-LO-PEG-HER NPs) exhibited promising potency and selectivity against HER2+ BC cells (BT474). The CS-LO-PEG-HER NPs demonstrated the cytotoxicity in BT474 cells by promoting reactive oxygen species, mitochondrial membrane potential loss, and nucleus damage. The biocompatibility of CS-LO-PEG-HER NPs was evidenced by the hemolysis assay and H & E staining of major organs. The CS-LO-PEG-HER NPs showed anticancer potency against the BT474-xenograft tumor-bearing mice, as evident by the reduction of tumor size and cell density. These results indicate that CS-LO-PEG-HER NPs are biocompatible with mice while inhibiting tumor growth through alter the oxidative stress. Overall, this work provides a promising approach for the delivery of LO for good therapeutic effect in combination with mAb.

Evaluation of Heterologous Biosynthetic Pathways for Methanol-Based 5-Aminovalerate Production by Thermophilic Bacillus methanolicus

The use of methanol as carbon source for biotechnological processes has recently attracted great interest due to its relatively low price, high abundance, high purity, and the fact that it is a non-food raw material. In this study, methanol-based production of 5-aminovalerate (5AVA) was established using recombinant Bacillus methanolicus strains. 5AVA is a building block of polyamides and a candidate to become the C5 platform chemical for the production of, among others, δ-valerolactam, 5-hydroxy-valerate, glutarate, and 1,5-pentanediol. In this study, we test five different 5AVA biosynthesis pathways, whereof two directly convert L-lysine to 5AVA and three use cadaverine as an intermediate. The conversion of L-lysine to 5AVA employs lysine 2-monooxygenase (DavB) and 5-aminovaleramidase (DavA), encoded by the well-known Pseudomonas putida cluster davBA, among others, or lysine α-oxidase (RaiP) in the presence of hydrogen peroxide. Cadaverine is converted either to γ-glutamine-cadaverine by glutamine synthetase (SpuI) or to 5-aminopentanal through activity of putrescine oxidase (Puo) or putrescine transaminase (PatA). Our efforts resulted in proof-of-concept 5AVA production from methanol at 50°C, enabled by two pathways out of the five tested with the highest titer of 0.02 g l^-1. To our knowledge, this is the first report of 5AVA production from methanol in methylotrophic bacteria, and the recombinant strains and knowledge generated should represent a valuable basis for further improved 5AVA production from methanol.

Plasma pharmacokinetics and tissue distribution of L-lysine α-oxidase from Trichoderma cf. aureoviride RIFAI VKM F- 4268D in mice

L-lysine α-oxidase (LO) is an L-amino acid oxidase with antitumor, antimicrobial and antiviral properties. Pharmacokinetic (PK) studies were carried out by measuring LO concentration in plasma and tissue samples by enzyme immunoassay. L-lysine concentration in samples was measured spectrophotometrically using LO. After single i.v. injection of 1.0, 1.5, 3.0 mg/kg the circulating T_1/2 of enzyme in mice varied from 51 to 74 min and the AUC_0-inf values were 6.54 ± 0.46, 8.66 ± 0.59, 9.47 ± 1.45 μg/ml × h, respectively. LO was distributed in tissues and determined within 48 h after administration with maximal accumulation in liver and heart tissues. Mean time to reach the maximum concentration was highest for the liver-9 h, kidney-1 h and 15 min for the tissues of heart, spleen and brain. T_1/2 of LO in tissues ranged from 7.75 ± 0.73 to 26.10 ± 2.60 h. In mice, plasma L-lysine decreased by 79% 15 min after LO administration in dose 1.6 mg/kg. The serum L-lysine levels remained very low from 1 to 9 h (< 25 μM, 17%), indicating an acute lack of L-lysine in animals for at least 9 h. Concentration of L-lysine in serum restored only 24 h after LO administration. The results of LO PK study show that it might be considered as a promising enzyme for further investigation as a potential anticancer agent.

Fungal Enzyme l-Lysine α-Oxidase Affects the Amino Acid Metabolism in the Brain and Decreases the Polyamine Level

The fungal glycoprotein l-lysine α-oxidase (LO) catalyzes the oxidative deamination of l-lysine (l-lys). LO may be internalized in the intestine and shows antitumor, antibacterial, and antiviral effects in vivo. The main mechanisms of its effects have been shown to be depletion of the essential amino acid l-lys and action of reactive oxidative species produced by the reaction. Here, we report that LO penetrates into the brain and is retained there for up to 48 h after intravenous injection, which might be explained by specific pharmacokinetics. LO actively intervenes in amino acid metabolism in the brain. The most significant impact of LO was towards amino acids, which are directly exposed to its action (l-lys, l-orn, l-arg). In addition, the enzyme significantly affected the redistribution of amino acids directly associated with the tricarboxylic acid (TCA) cycle (l-asp and l-glu). We discovered that the depletion of l-orn, the precursor of polyamines (PA), led to a significant and long-term decrease in the concentration of polyamines, which are responsible for regulation of many processes including cell proliferation. Thus, LO may be used to reduce levels of l-lys and PA in the brain.

Allosteric Enzyme-Based Biosensors-Kinetic Behaviours of Immobilised L-Lysine-α-Oxidase from Trichoderma viride: pH Influence and Allosteric Properties

The present study describes the kinetics of L-lysine-α-oxidase (LO) from Trichoderma viride immobilised by co-crosslinking onto the surface of a Pt electrode. The resulting amperometric biosensor was able to analyse L-lysine, thus permitting a simple but thorough study of the kinetics of the immobilised enzyme. The kinetic study evidenced that LO behaves in an allosteric fashion and that cooperativity is strongly pH-dependent. Not less important, experimental evidence shows that cooperativity is also dependent on substrate concentration at high pH and behaves as predicted by the Monod-Wyman-Changeux model for allosteric enzymes. According to this model, the existence of two different conformational states of the enzyme was postulated, which differ in Lys species landing on LO to form the enzyme-substrate complex. Considerations about the influence of the peculiar LO kinetics on biosensor operations and extracorporeal reactor devices will be discussed as well. Not less important, the present study also shows the effectiveness of using immobilised enzymes and amperometric biosensors not only for substrate analysis, but also as a convenient tool for enzyme kinetic studies.

[Effect of L-lysine alpha-oxidase from Trichoderma cf. aureoviride Rifai ВКМF-4268D on pheochromocytoma PC12 cell line]

L-Amino acid oxidases (L-ААО, EC 1.4.3.2) comprise a group of flavoproteins, catalyzing oxidative deamination of L-alpha amino acids to the corresponding alpha-keto acids, NH3 and Н2О2. In most cases these enzymes present homodimeric molecules with a molecular mass of 100-150 kDa, which were shown to possess antiviral, antifungal and antitumor activity. L-lysine alpha-oxidase (LO) holds an outstanding place among this group of enzymes and its biological role may differ significantly from the other L-AAO, because it cleaves an essential amino acid - L-lysine without significant action on the other amino acids. Although much research has examined LO effects in the organism, the molecular basis of these effects is yet to be identified. To fill this gap, the present work addressed one of hypothetical mechanisms of LO biological action using the enzyme from Trichoderma cf. aureoviride Rifai ВКМF-4268D and rat pheochromocytoma PC-12 as a model cell line. Using flow cytometry a dose-dependent cytotoxicity of LO was shown. The significant growth of intracellular reactive oxygen species levels, detected by 2,7-dichlorodihydrofluorescein assay, implies generation of peroxide as one of the molecular mechanisms of LO cytotoxic action, although this does not rule out other probable ways of LO action in the organizm.