Glutamine Metabolism and Prostate Cancer.

Glutamine (Gln) is a non-essential amino acid that is involved in the development and progression of several malignancies, including prostate cancer (PCa). While Gln is non-essential for non-malignant prostate epithelial cells, PCa cells become highly dependent on an exogenous source of Gln. The Gln metabolism in PCa is tightly controlled by well-described oncogenes such as MYC, AR, and mTOR.

Dual role of ER stress in response to metabolic co-targeting and radiosensitivity in head and neck cancer cells.

Arginine deprivation therapy (ADT) is a new metabolic targeting approach with high therapeutic potential for various solid cancers. Combination of ADT with low doses of the natural arginine analog canavanine effectively sensitizes malignant cells to irradiation. However, the molecular mechanisms determining the sensitivity of intrinsically non-auxotrophic cancers to arginine deficiency are still poorly understood.

Combinatory Treatment of Canavanine and Arginine Deprivation Efficiently Targets Human Glioblastoma Cells via Pleiotropic Mechanisms.

Glioblastomas are the most frequent and aggressive form of primary brain tumors with no efficient cure. However, they often exhibit specific metabolic shifts that include deficiency in the biosynthesis of and dependence on certain exogenous amino acids. Here, we evaluated, in vitro, a novel combinatory antiglioblastoma approach based on arginine deprivation and canavanine, an arginine analogue of plant origin, using two human glioblastoma cell models, U251MG and U87MG.

Indospicine combined with arginine deprivation triggers cancer cell death via caspase-dependent apoptosis.

Arginine-deprivation therapy is a rapidly developing metabolic anticancer approach. To overcome the resistance of some cancer cells to this monotherapy, rationally designed combination modalities are needed. In this report, we evaluated for the first time indospicine, an arginine analogue of Indigofera plant genus origin, as potential enhancer compound for the metabolic therapy that utilizes recombinant human arginase I.

Effects of Arginine and Its Deprivation on Human Glioblastoma Physiology and Signaling.

The observations that numerous cancers are characterized by impairment in arginine synthesis and that deficit of exogenous arginine specifically affects their growth and viability are the ground for arginine deprivation-based anticancer treatment strategy. This review addresses molecular mechanisms of the human glioblastoma cell response to arginine deprivation. Our earlier studies have shown that arginine deprivation specifically impairs glioblastoma cell motility, adhesion and invasiveness.

Glucose regulation in the methylotrophic yeast Hansenula (Ogataea) polymorpha is mediated by a putative transceptor Gcr1.

The HpGcr1, a hexose transporter homologue from the methylotrophic yeast Hansenula (Ogataea) polymorpha, was previously identified as being involved in glucose repression. Intriguingly, potential HpGcr1 orthologues are found only in the genomes of a few yeasts phylogenetically closely related to H. polymorpha, but are absent in all other yeasts.

Peroxisomes and peroxisomal transketolase and transaldolase enzymes are essential for xylose alcoholic fermentation by the methylotrophic thermotolerant yeast, .

Background: is one of the most thermotolerant xylose-fermenting yeast species reported to date. Several metabolic engineering approaches have been successfully demonstrated to improve high-temperature alcoholic fermentation by . Further improvement of ethanol production from xylose in depends on the identification of bottlenecks in the xylose conversion pathway to ethanol.

A Complex Scenario and Underestimated Challenge: The Tumor Microenvironment, ER Stress, and Cancer Treatment.

The paradoxical role of ER stress in malignant diseases is only just being unraveled and remains incompletely understood. A particular challenge is the complex interplay between spaciotemporal and locoregional microenvironmental constraints in solid tumors and stress responses upon treatment; thus, the potential for new combinatorial therapeutic options to foster the coincidence of ER stress-related deadly events is likely to be underestimated. Without claiming this review to be complete, we present a comprehensive overview of the signaling mechanisms associated with the unfolded protein response (UPR) and the molecular link to cell survival and death mechanisms.

A New Yeast Peroxin, Pex36, a Functional Homolog of Mammalian PEX16, Functions in the ER-to-Peroxisome Traffic of Peroxisomal Membrane Proteins.

Peroxisomal membrane proteins (PMPs) traffic to peroxisomes by two mechanisms: direct insertion from the cytosol into the peroxisomal membrane and indirect trafficking to peroxisomes via the endoplasmic reticulum (ER). In mammals and yeast, several PMPs traffic via the ER in a Pex3- and Pex19-dependent manner. In Komagataella phaffii (formerly called Pichia pastoris) specifically, the indirect traffic of Pex2, but not of Pex11 or Pex17, depends on Pex3, but all PMPs tested for indirect trafficking require Pex19.

Arginine Deprivation Therapy: Putative Strategy to Eradicate Glioblastoma Cells by Radiosensitization.

Tumor cells-even if nonauxotrophic-are often highly sensitive to arginine deficiency. We hypothesized that arginine deprivation therapy (ADT) if combined with irradiation could be a new treatment strategy for glioblastoma (GBM) patients because systemic ADT is independent of local penetration and diffusion limitations. A proof-of-principle study was performed with ADT being mimicked by application of recombinant human arginase or arginine-free diets.

Nitric oxide donor augments antineoplastic effects of arginine deprivation in human melanoma cells.

Anticancer therapy based on recombinant arginine-degrading enzymes has been proposed for the treatment of several types of malignant cells deficient in arginine biosynthesis. One of the predicted side effects of such therapy is restricted bioavailability of nitric oxide as arginine catabolic product. Prolonged NO limitation may lead to unwanted disturbances in NO-dependent vasodilation, cardiovascular and immune systems.

Co-application of canavanine and irradiation uncouples anticancer potential of arginine deprivation from citrulline availability.

The moderate anticancer effect of arginine deprivation in clinical trials has been linked to an induced argininosuccinate synthetase (ASS1) expression in initially ASS1-negative tumors, and ASS1-positive cancers are anticipated as non-responders. Our previous studies indicated that arginine deprivation and low doses of the natural arginine analog canavanine can enhance radioresponse. However, the efficacy of the proposed combination in the presence of extracellular citrulline, the substrate for arginine synthesis by ASS1, remains to be elucidated, in particular for malignant cells with positive and/or inducible ASS1 as in colorectal cancer (CRC).

Arginine starvation in colorectal carcinoma cells: Sensing, impact on translation control and cell cycle distribution.

Tumor cells rely on a continued exogenous nutrient supply in order to maintain a high proliferative activity. Although a strong dependence of some tumor types on exogenous arginine sources has been reported, the mechanisms of arginine sensing by tumor cells and the impact of changes in arginine availability on translation and cell cycle regulation are not fully understood. The results presented herein state that human colorectal carcinoma cells rapidly exhaust the internal arginine sources in the absence of exogenous arginine and repress global translation by activation of the GCN2-mediated pathway and inhibition of mTOR signaling.

Arginine deprivation induces endoplasmic reticulum stress in human solid cancer cells.

Deprivation for the single amino acid arginine is a rapidly developing metabolic anticancer therapy, which allows growth control in a number of highly malignant tumors. Here we report that one of the responses of human solid cancer cells to arginine starvation is the induction of prolonged endoplasmic reticulum (ER) stress and activation of the unfolded protein response (UPR). Systematic study of two colorectal carcinoma HCT-116 and HT29, glioblastoma U251 MG and ovarian carcinoma SKOV3 cell lines revealed, however, that the ER stress triggered by the absence of arginine does not result in massive apoptosis despite a profound upregulation of the proapoptotic gene CHOP.

Functional study of the Hap4-like genes suggests that the key regulators of carbon metabolism HAP4 and oxidative stress response YAP1 in yeast diverged from a common ancestor.

The transcriptional regulator HAP4, induced by respiratory substrates, is involved in the balance between fermentation and respiration in S. cerevisiae. We identified putative orthologues of the Hap4 protein in all ascomycetes, based only on a conserved sixteen amino acid-long motif.

Arginine deprivation affects glioblastoma cell adhesion, invasiveness and actin cytoskeleton organization by impairment of β-actin arginylation.

A deficit of exogenous arginine affects growth and viability of numerous cancer cells. Although arginine deprivation-based strategy is currently undergoing clinical trials, molecular mechanisms of tumor cells' response to arginine deprivation are not yet elucidated. We have examined effects of arginine starvation on cell motility, adhesion and invasiveness as well as on actin cytoskeleton organization of human glioblastoma cells.

Recombinant arginine-degrading enzymes in metabolic anticancer therapy and bioanalytics.

Tumor cells often exhibit specific metabolic defects due to the aberrations in oncogene-dependent regulatory and/or signaling pathways that distinguish them from normal cells. Among others, many malignant cells are deficient in biosynthesis of certain amino acids and concomitantly exhibit elevated sensitivity to deprivation of these amino acids. Although the underlying causes of such metabolic changes are still not fully understood, this feature of malignant cells is exploited in metabolic enzymotherapies based on single amino acid, e.

Single amino acid arginine deprivation triggers prosurvival autophagic response in ovarian carcinoma SKOV3.

Autophagy is a process of cytosol-to-lysosome vesicle trafficking of cellular constituents for degradation and recycling of their building blocks. Autophagy becomes very important for cell viability under different stress conditions, in particular under amino acid limitation. In this report we demonstrate that single amino acid arginine deprivation triggers profound prosurvival autophagic response in cultured human ovarian cancer SKOV3 cells.

Stable overproducer of hepatitis B surface antigen in the methylotrophic yeast Hansenula polymorpha due to multiple integration of heterologous auxotrophic selective markers and defect in peroxisome biogenesis.

Two methods of multicopy integrant selection in the methylotrophic yeast Hansenula polymorpha based on the use of heterologous yeast auxotrophic genes have been used to isolate effective overproducers of hepatitis B surface antigen (HBsAg). One selection marker was described earlier for this yeast, the Saccharomyces cerevisiae URA3 gene, whereas the second selection marker was developed by us, the Pichia pastoris ADE1 gene with shortened native promoter. Sequential use of both selection markers produced stable transformants containing up to 30 integration cassettes with HBsAg gene.

Three-dimensional environment renders cancer cells profoundly less susceptible to a single amino acid starvation.

Increased amino acid requirement of malignant cells is exploited in metabolic antitumor therapy, e.g., enzymotherapies based on arginine or methionine deprivation.

Overexpression of (His)6-tagged human arginase I in Saccharomyces cerevisiae and enzyme purification using metal affinity chromatography.

Arginase (EC 3.5.3.

Single amino acid arginine starvation efficiently sensitizes cancer cells to canavanine treatment and irradiation.

Single amino acid arginine deprivation is a promising strategy in modern metabolic anticancer therapy. Its potency to inhibit tumor growth warrants the search for rational chemo- and radio-therapeutic approaches to be co-applied. In this report, we evaluated, for the first time, the efficacy of arginine deprivation as anticancer therapy in three-dimensional (3D) cultures of human tumor cells, and propose a new combinatorial metabolic-chemo-radio-treatment regime based on arginine starvation, low doses of arginine natural analog canavanine and irradiation.

Atg35, a micropexophagy-specific protein that regulates micropexophagic apparatus formation in Pichia pastoris.

Autophagy-related (Atg) pathways deliver cytosol and organelles to the vacuole in double-membrane vesicles called autophagosomes, which are formed at the phagophore assembly site (PAS), where most of the core Atg proteins assemble. Atg28 is a component of the core autophagic machinery partially required for all Atg pathways in Pichia pastoris. This coiled-coil protein interacts with Atg17 and is essential for micropexophagy.

Canavanine augments proapoptotic effects of arginine deprivation in cultured human cancer cells.

Arginine deprivation achieved by means of recombinant arginine-degrading enzymes is currently being developed as a novel anticancer enzymotherapy. In this study, we showed that arginine deprivation in vitro profoundly and selectively sensitized human cancer cells of different organ origin to low doses of canavanine, an arginine analogue of plant origin. In sensitive cancer cells arginine starvation led to the activation of caspase-9, caspase-3 and caspase-7, cleavage of reparation enzyme, polyADP ribosyl polymerase, and DNA fragmentation, which are the typical hallmarks of intrinsic apoptosis realized by the mitochondrial pathway.

Cancer cell sensitivity to arginine deprivation in vitro is not determined by endogenous levels of arginine metabolic enzymes.

Single amino acid Arg (arginine) deprivation is currently considered as a therapeutic approach to treat certain types of tumours; the molecular mechanisms that underlie tumour cell sensitivity or resistance to Arg restriction are still little understood. Here, we address the question of whether endogenous levels of key Arg metabolic enzymes [catabolic: arginases, ARG1 (arginase type 1) and ARG2 (arginase type 2), and anabolic: OTC (ornithine transcarbamylase) and ASS (argininosuccinate synthetase)] affect cellular responses to arginine deprivation in vitro. Human epithelial cancer cells of different organs of origin exhibiting variable sensitivity to Arg deprivation provided the experimental models.