7-Methylguanine Inhibits Colon Cancer Growth in Vivo.

7-Methylguanine (7-MG) is a natural inhibitor of poly(ADP-ribose) polymerase 1 and tRNA-guanine transglycosylase, the enzymatic activity of which is central for the proliferation of cancer cells. Recently, a number of preclinical tests have demonstrated the safety of 7-MG and a regimen of intragastric administration was established in mice. In the present work, the pharmacological activity of 7-MG was studied in BALB/c and BALB/c nude mice with transplanted tumors. It was found that 7-MG effectively penetrates tumor tissue and suppresses colon adenocarcinoma growth in the Akatol model, as well as in a xenograft model with human HCT116 cells.

[Stochastic Packaging of Cas Proteins into Exosomes].

CRISPR/Cas systems are perspective molecular tools for targeted manipulation with genetic materials, such as gene editing, regulation of gene transcription, modification of epigenome etc. While CRISPR/Cas systems proved to be highly effective for correcting genetic disorders and treating infectious diseases and cancers in experimental settings, clinical translation of these results is hampered by the lack of efficient CRISPR/Cas delivery vehicles. Modern synthetic nanovehicles based on organic and inorganic polymers have many disadvantages, including toxicity issues, the lack of targeted delivery, and complex and expensive production pipelines. In turn, exosomes are secreted biological nanoparticles that exhibit high biocompatibility, physico-chemical stability, and the ability to cross biological barriers. Early clinical trials found no toxicity associated with exosome injections. In the recent years, exosomes have been considered as perspective delivery vehicles for CRISPR/Cas systems in vivo. The aim of this study was to analyze the efficacy of CRISPR/Cas stochastic packaging into exosomes for several human cell lines. Here, we show that Cas9 protein is effectively localized into the compartment of intracellular exosome biogenesis, but stochastic packaging of Cas9 into exosomes turns to be very low (~1%). As such, stochastic packaging of Cas9 protein is very ineffective and cannot be used for gene editing purposes. Developing novel tools and technologies for loading CRISPR/Cas systems into exosomes is needed.

Methionine gamma lyase fused with S3 domain VGF forms octamers and adheres to tumor cells via binding to EGFR.

Methods for targeting enzymes exhibiting anticancer properties, such as methionine γ-lyase (MGL), have not yet been sufficiently developed. Here, we present the data describing the physico-chemical properties and cytotoxic effect of fusion protein MGL-S3 - MGL from Clostridium sporogenes translationally fused to S3 domain of the viral growth factor of smallpox. MGL-S3 has methioninase activity comparable to native MGL. In solution, MGL-S3 protein primarily forms octamers, whereas native MGL, on the contrary, usually forms tetramers. MGL-S3 binds to the surface of the neuroblastoma SH-SY5Y and epidermoid carcinoma A431 cells and, unlike native MGL, remains there and retains its cytotoxic effect after media removal. In HEK293T cells lacking EGFRs, no adhesion was recorded. Confocal fluorescence microscopy confirms the preferential adhesion of MGL-S3 to tumor cells, while it avoids getting into lysosomes. Both MGL and MGL-S3 arrest cell cycle of SH-SY5Y cells mainly in the G1 phase, while only MGL-S3 retains this ability after washing the cells.

Daidzein-directed methionine γ-lyase in enzyme prodrug therapy against breast cancer.

Thiosulfinates in situ formed by "pharmacological pair" C115H methionine γ-lyase/S-(allyl/alkyl)-l-cysteine sulfoxides possess cytotoxic activity against various malignant cell lines. To investigate in vivo antitumor activity of thiosulfinates generated directly at the surface of tumor cells, a chemical conjugate between Clostridium novyi C115H methionine γ-lyase (C115H MGL) and isoflavone daidzein was prepared. The binding of conjugate (C115H-Dz) to various breast cancer cell lines was demonstrated, as well as its cytotoxicity in the presence of S-(allyl/alkyl)-l-cysteine sulfoxides. The most promising among thiosulfinates was dipropyl thiosulfinate (IC50 < 0.53 µM). The pharmacokinetic parameters of C115H MGL and C115H-Dz were obtained. Plasma half-lives of the enzyme and conjugated enzyme were 4.4 and 7.2 h, respectively. In vivo antitumor effect of pharmacological pairs on SKBR-3 xenografts was demonstrated. Treatment of tumor-bearing mice with a pair of C115H-Dz/propiin inhibited tumor growth by 85%.

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 T1/2 of enzyme in mice varied from 51 to 74 min and the AUC0-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. T1/2 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.

Effect of Heterologous Expression of Chemotaxis Proteins from Genus Thermotoga on the Growth Kinetics of Escherichia coli Cells.

In the process of optimization of heterologous expression of thermostable chemotaxis proteins CheW and CheY as industrially useful polypeptides, their direct influence on the cell growth kinetics and morphology of Escherichia coli was observed. CheW and CheY of bacteria of the genus Thermotoga, being expressed in recombinant form in E. coli cells, are involved in the corresponding signal pathways of the mesophilic microorganisms. The effects of such involvement in the metabolism of "host" cells are extremely diverse: from rapid aging of the culture to elongation of the stationary growth phase. We also discuss the mechanisms of the influence of the heterologous chemotaxis proteins on cells, their positive and negative effects, as well as potential applications in industry and biomedicine.

Methionine Gamma Lyase from Clostridium sporogenes Increases the Anticancer Efficacy of Doxorubicin on A549 Cancer Cells In Vitro and Human Cancer Xenografts.

The anticancer efficacy of methionine γ-lyase (MGL) from Clostridium sporogenes (C. sporogenes) is described. MGL was active against cancer cells in vitro and in vivo. Doxorubicin (DOX) and MGL were more effective on A549 human lung-cancer growth inhibition than either agent alone in vitro and in vivo.

Methionine gamma lyase from Clostridium sporogenes increases the anticancer effect of doxorubicin in A549 cells and human cancer xenografts.

The anti-cancer efficacy of methionine γ-lyase (MGL) from Clostridium sporogenes (C. sporogenes) is described. MGL was active against cancer models in vitro and in vivo. The calculated EC50 values for MGL were 4.4 U/ml for A549, 7.5 U/ml for SK-BR3, 2.4 U/ml for SKOV3, and 0.4 U/ml for MCF7 cells. The combination of doxorubicin (DOX) and MGL was more effective for A549 human lung cancer growth inhibition than either agent alone in vitro and in vivo. MGL reduced the EC50 of doxorubicin from 35.9 µg/mL to 0.01-0.265 µg/mL. The growth inhibitory effect of DOX + MGL on A549 xenografts in vivo was reflective of the results obtained in vitro. The inhibition rate of tumor growth in the combined arm was 57%, significantly higher than that in the doxorubicin (p = 0.033)-alone arm.

Thermostable Recombinant Polypeptides as the Source of L-Amino Acids for Culture Media.

Mutant homologues of small chemotactic and DNA-binding proteins from thermophilic bacteria Thermotoga petrophila RKU-1 and Thermotoga naphthophila were obtained. These proteins can be expressed in the recombinant form in E. coli cells. A wide range of properties and parameters that are important for isolation of these proteins were revealed: stability in a wide temperature and pH range, high level of expression, solubility, and the possibility of using simple purification schemes with low number of successive steps. The positive effect of proteins on in vitro fibroblasts growth was demonstrated. The described properties of the target proteins indicate the possibility of their use in different biotechnology industries as an inexpensive source of L-amino acids.

[Construction and characterization of a recombinant mutant homolog of the CheW protein from Thermotoga petrophila RKU-1]. / Poluchenie i kharakteristika rekombinantnogo mutantnogo gomologa belka CheW iz gipertermofil'nogo mikroorganizma Thermotoga petrophila RKU-1.

In the work a recombinant chemotaxis protein CheW from Thermotoga petrophila RKU-1 (TpeCheW) and its mutant homolog (TpeCheW-mut) were created. It was shown that, despite the low homology with CheW prototypes from intestinal bacteria, these proteins didn't cause metabolic overload and were well expressed by cells of E. coli laboratory strains. We have discovered a broad spectrum of industrial valuable properties of the TpeCheW-mut protein such as stability in a wide range of temperatures and pH, high expression level, solubility and possibility of the application of a simple low-stage purification methodology with the use of preliminary heat treatment. Possible directions of the scientific and industrial application of this protein were claimed.

Intracellular Localization of Apoptotic Endonuclease EndoG and Splice-Variants of Telomerase Catalytic Subunit hTERT.

The activity of telomerase catalytic subunit hTERT (human telomerase reverse transcriptase) can be regulated by alternative splicing of its mRNA. The mechanism of hTERT splicing is not understood in detail. Apoptotic endonuclease EndoG is known to participate in this process. In the present work, the intracellular colocalization and mRNA levels of EndoG and hTERT splice-variants in normal and apoptotic cancer cells were studied. We found that the development of apoptosis increased the expression of EndoG and changed the ratio of hTERT splice-variants, which decreased the telomerase activity in the cells. The development of apoptosis was accompanied by changes in the amount of mRNA and in the localization of EndoG and hTERT splice-variants in the cytoplasm, nuclei, and mitochondria of the cells. The suppression of EndoG expression using RNA interference prevented induction of the α+ß- splice-variant of hTERT and inhibition of the telomerase activity. A high degree of the intracellular colocalization of EndoG and hTERT was shown. The changes in the expression and localization of EndoG corresponded with changes in the amount and localization of hTERT splice-variants. These data confirm the participation of EndoG in the alternative splicing of mRNA of the telomerase catalytic subunit and in regulation of the telomerase activity.

[Prediction of protein thermostability from their primary structure: the current state and development factors]. / Prognozirovanie termostabil'nosti belkov po ikh pervichnoi strukture: sovremennoe sostoianie i faktory razvitiia.

The construction of proteins and peptides with desired properties, including resistance to high temperatures, as well as optimization of their amino acid composition, is an important and complex task, which attracts much attention in various branches of the basic sciences, and also in biomedicine and biotechnology. This raises the question: what method is more relevant for the at the pilot stage of research in order to estimate the influence of the planned amino acid substitutions on the thermostability of the resultant protein construct? In this brief review we have classified existing basic practical and theoretical approaches used in studies and predicting the thermal stability of native and recombinant polypeptides. Particular attention has been paid to the predictive potential of statistical methods for studying the thermodynamic parameters of the primary protein structure and prospects of their use.

[Cisplatin-induced apoptotic endonuclease EndoG inhibits telomerase activity and causes malignant transformation of human CD4+ T lymphocytes]. / Indutsirovannaia tsisplatinom ékspressiia apoptoticheskoi éndonukleazy EndoG vyzyvaet ingibirovanie aktivnosti telomerazy i zlokachestvennuiu transformatsiiu CD4+ T-limfotsitov cheloveka.

Alternative splicing of telomerase catalytic subunit hTERT pre-mRNA (human Telomerase Reverse Transcriptase) regulates telomerase activity. Increased expression of non-active splice variant hTERT results in inhibition of telomerase. Apoptotic endonuclease EndoG is known to participate in hTERT alternative splicing. Expression of EndoG can be induced in response to DNA damages. The aim of this study was to determine the ability of a DNA-damaging compound, cisplatin, to induce EndoG and its influence on alternative splicing of hTERT and telomerase activity in human CD4+ Т lymphocytes. Overexpression of EndoG in CD4+ T cells downregulated the expression of active full-length hTERT variant and upregulated its non-active spliced variant. Reduction of full-length hTERT caused downregulation of telomerase activity, shortening of telomeres length during cell divisions, converting cells to the replicative senescence state, activation of apoptosis and finally cell death. Few cells survived and underwent malignant transformation. Transformed cells have increased telomerase activity and proliferative potential compare to initial CD4+ T cells. These cells have phenotype of T lymphoblastic leukemic cells and are able to form tumors and cause death in experimental mice.

Plasma methionine depletion and pharmacokinetic properties in mice of methionine γ-lyase from Citrobacter freundii, Clostridium tetani and Clostridium sporogenes.

PK studies were carried out after a single i.v. administration of 500 and 1000 U/kg by measuring of MGL activity in plasma samples. L-methionine concentration was measured by mass spectrometry. After single i.v. injection of 500U/kg the circulating T1/2 of enzymes in mice varies from 73 to 123min. The AUC0-tinf values determined for MGL 500U/kg from C. freundii, C. tetani and C. sporogenes are 8.21±0.28, 9.04±0.33 and 13.88±0.39U/(ml×h), respectively. Comparison of PK parameters of three MGL sources in the dose of 500U/kg indicated the MGL C. sporogenes to have better PK parameters: clearance 0.83(95%CI: 0.779-0.871) - was lower than C. tetanii 1.27(95%CI: 1.18-1.36) and C. freundii 1.39(95%CI: 1.30-1.49). Mice plasma methionine decreased to undetectable level 10min after MGL 1000 U/kg injection. After MGL C. sporogenes 500U/kg injection plasma methionine level completely omitted after 10min till 6h, assuming the sustainability of negligible levels of methionine (<5µM) in plasma of mice for about 6h. The recovery of methionine concentration showed the advantageous efficiency of MGL from C. sporogenes: 95% 0.010-0.022 vs 0.023-0.061 for MGL C. freundii and 0.036-0.056 for MGL C. tetani. There are no significant differences between methionine cleavage after MGL C. tetani and MGL C. sporogenes i.v. injection at all doses. MGL from C. sporogenes may be considered as promising enzyme for further investigation as potential anticancer agent.

[Bioactive proteins and peptides: current state and new trends of practical application in the food industry and feed production].

Proteins and polypeptides play a key role in the life of a human body. Scientific and practical interest to the natural proteinaceous substances could be explained by the diversity of their functions in metabolic processes. Biologically active substances of the protein origin have a rich history of applications in different sectors of the economy. In this case, the close relationship is observed between food industry, biomedicine and fodder production, because efficient conversion of feed protein in productive agricultural animals provides, as a result, the required level of metabolism in a human, as the main consumer of final products derived from these animals. Obviously, for normal growth, development and resistance to infectious agents, both people and farm animals need a constant consumption of L-amino acids in certain proportions and in available for absorption form. This review considers the bioactive polypeptides used in nutrition and food industry, main trends and practical approaches to generating protein products with the desired characteristics.

[Apoptotic endonuclease EndoG induces alternative splicing of telomerase catalytic subunit hTERT and death of tumor cells]. / Éndonukleaza EndoG indutsiruet al'ternativnyi splaising kataliticheskoi sub"edinitsy telomerazy hTERT i gibel' opukholevykh kletok.

Telomerase activity is known to be regulated by alternative splicing of its catalytic subunit hTERT (human Telomerase Reverse Transcriptase) mRNA. Induction of non-active spliced hTERT leads to inhibition of telomerase activity. However, very little is known about the mechanism of hTERT mRNA alternative splicing. The aim of this study was to determine the role of apoptotic endonuclease EndoG in alternative splicing of hTERT and telomerase activity. Strong correlation was found between expression of EndoG and hTERT splice-variants in 12 colon cancer cell lines. Overexpression of EndoG in СаСо-2 cells downregulated the expression of active full-length hTERT variant and upregulated non-active spliced variant. Reduction of full-length hTERT caused downregulation of telomerase activity, dramatically shortening of telomeres length during cell divisions, converting cells to the replicative senescence state, activation of apoptosis and finally cell death. These data indicated the participation of EndoG in alternative splicing of mRNA of telomerase catalytic subunit, regulation of telomerase activity and cell fate.

The Modified Heparin-Binding L-Asparaginase of Wolinella succinogenes.

The modified asparaginase Was79 was derived from the recombinant wild-type L-asparaginase of Wolinella succinogenes. The Was79 contains the amino acid substitutions V23Q and K24T responsible for the resistance to trypsinolysis and the N-terminal heparin-binding peptide KRKKKGKGLGKKR responsible for the binding to heparin and tumor K562 cells in vitro. When tested on a mouse model of Fischer lymphadenosis L5178Y, therapeutic efficacy of Was79 was significantly higher than that of reference enzymes at all single therapeutic doses used (125-8000 IU/kg). At Was79 single doses of 500-8000 IU/kg, the complete remission rate of 100 % was observed. The Was79 variant can be expressed intracellularly in E. coli as a less immunogenic formyl-methionine-free form at high per cell production levels.

Identification of functional regions in the Rhodospirillum rubrum L-asparaginase by site-directed mutagenesis.

Site-directed mutagenesis of Rhodospirillum rubrum L-asparaginase (RrA) was performed in order to identify sites of the protein molecule important for its therapeutic and physico-chemical properties. Ten multipoint mutant genes were obtained, and five recombinant RrA variants were expressed in E. coli BL21(DE3) cells and isolated as functionally active highly purified proteins. Protein purification was performed using Q-Sepharose and DEAE-Toyopearl chromatography. Overall yield of the active enzymes was 70-80 %, their specific activity at pH 7.4 and 37 °C varied of 140-210 U/mg. L-Glutaminase activity did not exceed 0.01 % of L-asparaginase activity. All RrA mutants showed maximum enzyme activity at pH 9.3-9.5 and 53-58 °C. Km and Vmax values for L-asparagine were evaluated for all mutants. Mutations G86P, D88H, M90K (RrAH), G121L, D123A (RrАI) caused the loss of enzyme activity and confirmed the importance of these sites in the implementation of catalytic functions. Removal of four residues from C-terminal area of the enzyme (RrAK) resulted in the enzyme instability. Mutations D60K, F61L(RrАD), and R118H, G120R(RrАJ) led to the improvement of kinetic parameters and enzyme stabilization. Substitutions E149R, V150P (RrАB) improved antineoplastic and cytotoxic activity of the RrA. A64V, E67K substitutions, especially in combination with E149R, V150P (RrАE), considerably destabilized recombinant enzyme.

Kinetic Parameters and Cytotoxic Activity of Recombinant Methionine γ-Lyase from Clostridium tetani, Clostridium sporogenes, Porphyromonas gingivalis and Citrobacter freundii.

The steady-state kinetic parameters of pyridoxal 5'-phosphate-dependent recombinant methionine γ -lyase from three pathogenic bacteria, Clostridium tetani, Clostridium sporogenes, and Porphyromonas gingivalis, were determined in ß- and γ-elimination reactions. The enzyme from C. sporogenes is characterized by the highest catalytic efficiency in the γ-elimination reaction of L-methionine. It was demonstrated that the enzyme from these three sources exists as a tetramer. The N-terminal poly-histidine fragment of three recombinant enzymes influences their catalytic activity and facilitates the aggregation of monomers to yield dimeric forms under denaturing conditions. The cytotoxicity of methionine γ-lyase from C. sporogenes and C. tetani in comparison with Citrobacter freundii was evaluated using K562, PC-3, LnCap, MCF7, SKOV-3, and L5178y tumor cell lines. K562 (IC50=0.4-1.3 U/ml), PC-3 (IC50=0.1-0.4 U/ml), and MCF7 (IC50=0.04-3.2 U/ml) turned out to be the most sensitive cell lines.

Cloning, expression and characterization of the recombinant Yersinia pseudotuberculosis L-asparaginase.

We have cloned ansB (YPTB1411) gene from Yersinia pseudotuberculosis Q66CJ2 and constructed stable inducible expression system that overproduce L-asparaginase from Y. pseudotuberculosis (YpA) in Escherichiacoli BL21 (DE3) cells. For purification of YpA we used Q-Sepharose and DEAE-Toyopearl column chromatography. We examined kinetics of the enzyme reaction, catalytic activity as a function of pH, temperature and ionic strength, thermostability and other enzyme properties. Biochemical properties of YpA are similar with those of E. coli type II L-asparaginase. K(m) for L-asparagine is 17 ± 0.9 µM and pI 5.4 ± 0.3. Enzyme demonstrates maximum activity at pH 8.0 and 60 °C. YpA L-glutaminase activity is relatively low and more than 15 times less than specific activity towards L-asn. We evaluated also the antiproliferative effect of YpA in vitro and in vivo with E. colil-asparaginase (EcA) as the reference substance at similar conditions.