A New Efficient Method for Production of Recombinant Antitumor Cytokine TRAIL and Its Receptor-Selective Variant DR5-B.

The cytokine TRAIL induces apoptosis in tumor cells of various origin without affecting normal cells. Clinical trials of TRAIL-receptor (DR4 and DR5) agonists (recombinant TRAIL or death receptors antibodies) have largely failed because most human tumors were resistant to them. Currently, a second generation of agents targeted at TRAIL-R with increased efficiency has been developed. To this end, we have developed DR5-B, a variant of TRAIL selectively interacting with DR5. We have developed a new efficient method for production of TRAIL and DR5-B using expression of these proteins in Escherichia coli strain SHuffle B. The proteins were isolated from the cytoplasmic fraction of cells and purified to a high degree of homogeneity using metal-affinity and ion-exchange chromatography. The protein yield was 211 and 173 mg from one liter of cell culture for DR5-B and TRAIL, respectively, which significantly exceeded the results obtained by other methods. DR5-B killed tumor cells of different origin more efficiently and rapidly compared with TRAIL. The resulting preparations can be used for the study of TRAIL signaling pathways and in preclinical and clinical trials as antitumor agents.

The effect of cisplatin on cytotoxicity of anticancer cytokine TRAIL and its receptor-selective mutant variant DR5-B1.

Cytokine TRAIL selectively induces apoptosis in vitro and in vivo in tumor cells without affecting normal cells, but its therapeutic application is limited, since many primary tumors are insensitive to TRAIL. To improve the efficiency of TRAIL, we have previously developed TRAIL mutant variant DR5-B, which binds the apoptosis-inducing death receptor DR5 as efficiently as wild type TRAIL, but shows almost no affinity to other receptors. In this study, we investigated the effect of the chemotherapeutic agent cisplatin on the cytotoxicity of TRAIL variants in 12 tumor cell lines of various origin. Cisplatin effectively enhances the cytotoxic activity of TRAIL preparations. The synergistic effect is most pronounced in the prostate cancer cell lines, where the combined effect exceeds the sum of the separate effects by more than 2 times. The cytotoxicity of DR5-B variant is significantly higher compared to wild-type TRAIL in combination with cisplatin in 9 of 12 tumor cell lines.

Mutations Enhancing Selectivity of Antitumor Cytokine TRAIL to DR5 Receptor Increase Its Cytotoxicity against Tumor Cells.

Tumor necrosis factor superfamily cytokine TRAIL (tumor necrosis factor-related apoptosis-inducing ligand) induces apoptosis in tumor cells by binding to death receptors DR4 and DR5 without affecting normal cells. However, the therapeutic use of TRAIL is limited, because many tumor cells are resistant to it. The resistance is partially related to interaction of TRAIL with the decoy receptors DcR1 and DcR2, which do not trigger the apoptotic signal and inhibit signaling of death receptors. Previously, we designed a unique DR5-specific TRAIL mutant variant DR5-B, which binds to DR5 receptor as effectively as the original cytokine, but has practically no interaction with DR4 and DcR1 receptors, and its affinity for DcR2 is reduced 400-fold. In the present work, the cytotoxity of TRAIL and DR5-B was analyzed on 12 different tumor cell lines and two types of normal cells. In nine of 12 tumor cell lines, DR5-B killed 1.5-5.0 times more tumor cells than TRAIL, and it did not exhibit toxicity towards normal cells. Chemotherapeutic drugs such as doxorubicin, paclitaxel, and bortezomib augmented the effect of both TRAIL variants, and the enhancing effect was more pronounced for DR5-B. Half-maximal effective concentrations (EC50) for DR5-B in combination with chemotherapeutic agents were 1.5-10.0 times lower than for wild-type TRAIL. Thus, DR5-B is a promising candidate both for monotherapy and in combination with chemotherapy for treatment of TRAIL-resistant tumors.

[The influence of solcoseryl on population and cellular parameters of HeLa and RD cultures].

Changes of population and cellular parameters of HeLa and RD cultures after introducing of solcoseryl in culture medium were studied by methods of scanning cytophotometry and cytomorphometry. Monolayer density, proliferation activity, the number of dead cells in a monolayer, the number of nucleoli in nuclei and distribution of cells in the populations by this parameter, RNA and DNA masses in nuclei and nucleoli, total volumes and surface areas of the nuclei and nucleoli were determined. It has been shown that solcoseryl differently affects the cultures both on population and on cellular levels of their organization. The results of multi-parametric analysis of the influence of solseryl on the cultures allow considering it as a biologically active compound with the features typical for cell and cell population growth regulating factors.

[Immune reactivity and cytokine status in polytrauma].

The PHA-induced and serum levels of IFN-alpha and -gamma, TNF-alpha, IL-4, IL-6, IL-8, IL-RA, as well as CD3, CD4, CD8, CD20, CD56 lymphocytic subpopulations and serum IgG, IgM, and IgA were studied in 53 patients with multiple trauma to detect the most informative parameters of laboratory monitoring of the immunodeficiency developing during treatment. The stages of the study corresponded to the phases of development of an immune response: (1) an induction phase (days 1-4); (2) an immunoregulatory phase (days 5-10); (3) an effector phase (days 11-24). The findings suggest that at the early stage of the study, the drastic reduction was revealed in CD3, CD4 T-lymphocytic subpopulations, accompanied by inadequate humoral immunological parameters. By Stage 3 of the study, the majority of these parameters became normal; the serum levels of IgG and IgM remained lower only in patients with a fatal outcome. Throughout all the 3 stages of the study, the serum concentration of IFN-alpha remained in the almost normal ranges; there was no significant elevation in both the serum and induced levels of IL-4 either. The serum content of TNF-alpha in the examinees was significantly higher than the normal levels, by remaining virtually at the same level up to the end of treatment. The elevated serum levels of TNF-alpha were attended by its increased induction in vitro, without reducing up to Stage 3. From Stage 3, only some patients with a fatal outcome were observed to have the reduced induced and spontaneous levels of TNF-alpha. According to the findings, at Stage 1 of the study, the production of IFN-gamma in all patients was much increased, by significantly dropping by the end of treatment (by more than twice), without achieving, however, the normal levels, except the examinees with a fatal outcome, in whom the concentration of IFN-alpha increased or underwent no changes. A relationship was also found between the serum levels of IL-6 and IL-8 and the outcome of the disease: throughout the observation, their concentrations remained invariably high in patients with a fatal outcome whereas in those with a good outcome, there was a uniform decrease in the content of both cytokines by the end of the observation. Thus, the simultaneous increase in the levels of IFN-gamma, IL-6, IL-8, and TNF-alpha and accompanying reductions in CD3, CD4 and serum IgG, IgM are poor prognostic factors and may be used both as additional immunodiagnostic criteria and for immunotherapy monitoring in patients with polytrauma.

Overexpression in Escherichia coli and purification of human fibroblast growth factor (FGF-2).

Basic fibroblast growth factor (FGF-2) is a member of a large family of structurally related proteins that affect the growth, differentiation, migration, and survival of many cell types. The human FGF-2 gene (encoding residues 1-155) was synthesized by PCR from 20 oligonucleotides and cloned into plasmid pET-32a. A high expression level (1 g/liter) of a fused protein thioredoxin/FGF-2 was achieved in Escherichia coli strain BL21(DE3). The fusion protein was purified from the soluble fraction of cytoplasmic proteins on a Ni-NTA agarose column. After cleavage of the thioredoxin/FGF-2 fusion with recombinant human enteropeptidase light chain, the target protein FGF-2 was purified on a heparin-Sepharose column. The yield of FGF-2 without N- and C-terminal tags and with high activity was 100 mg per liter of cell culture. Mutations C78S and C96S in the amino acid sequence of the protein decreased FGF-2 dimer formation without affecting its solubility and biological activity.

[Multiparametric study and cluster-analysis of the transformed cultures of human cells].

The cells of nepatocarcinoma (HEp-G2), adenocarcinoma of large intestine (Caco-2), embryonal kidney (HEK-293), neuroblastoma (SH-SY5Y), rabdomyosarcoma (RD), and larynx cancer (Hep-2) were studied by the methods of scanning cytophotometry, cytochemistry and cytomorphometry during 96 h of cultivation. The density of monolayers, proliferation activity, the number of dead cells, DNA content in the nuclei and distribution of the cells in the population by this parameter, total DNA content in the nucleoli (circumnucleolar chromatin), the number of nucleoli in the nuclei, distribution of cells by their number, the volume and area of the nucleus surface, total volume and area of the nucleoli surface were determined. The data obtained were used in the treelike cluster analysis of the cultures by Pierson correlation. As a result, the SH-SY5Y culture was put in a separate cluster, while Caco-2, HEp-G2, HEK-293, Hep-2 and RD cultures were placed in the tree of another cluster. The least transformed culture of neuroblastoma (SH-SY5Y) had no relationship with other cultures, which showed various rate of similarity. The cultured HEK-293, Hep-2 and RD appeared to be close to each other by all parameters. The parameters studied are of different significance for the formation of general pattern of the cell cultures. The greatest "weight" is carried by the parameters, which characterize the population as whole: the density of the monolayer, mitotic coefficient and the number of dead cells. They are followed by the content of DNA in the nuclei, the total area of the nucleoli surface, and ratios of DNA content in the nucleoli to DNA content in the nucleus and of total surface of the nucleoli to the surface of the nuclei. Other parameters are not so significant.

Infection of stromal and hemopoietic precursor cells with lentivirus vector in vivo and in vitro.

We developed a method for gene transfer into mesenchymal stromal cells. Lentivirus vector containing green fluorescent protein gene for labeling stromal and hemopoietic precursor cells was obtained using two plasmid sets from different sources. The vector was injected into the femur of mice in vivo and added into culture medium for in vitro infection of the stromal sublayer of long-term bone marrow culture. From 25 to 80% hemopoietic stem cells forming colonies in the spleen were infected with lentivirus vector in vivo and in vitro. Fibroblast colony-forming cells from the femoral bones of mice injected with the lentivirus vector carried no marker gene. The marker gene was detected in differentiated descendants from mesenchymal stem cells (bone cavity cells from the focus of ectopic hemopoiesis formed after implantation of the femoral bone marrow cylinder infected with lentivirus vector under the renal capsule of syngeneic recipient). In in vitro experiments, the marker gene was detected in sublayers of long-term bone marrow cultures infected after preliminary 28-week culturing, when hemopoiesis was completely exhausted. The efficiency of infection of stromal precursor cells depended on the source of lentivirus. The possibility of transfering the target gene into hemopoietic precursor cells in vivo is demonstrated. Stromal precursor cells can incorporate the provirus in vivo and in vitro, but conditions and infection system for effective infection should be thoroughly selected.

Cytoskeleton inhibitors combined with TRAIL induce apoptosis in HeLa carcinoma cells overexpressing antiapoptotic protein Bcl-2.

TRAIL (Apo2L), a cytokine from the family of tumor necrosis factors (TNF), causes apoptosis in various types of tumor cells but is not toxic for normal cells. Recombinant TRAIL obtained using an original method stimulates the release of cytochrome c from mitochondria into the cytoplasm and apoptosis in HeLa carcinoma cells. Expression of oncoprotein Bcl-2 in these cells blocks both processes. The microtubule inhibitors taxol, nocodazole, and colcemid, as well as an inhibitor of actin microfilaments cytochalasin D, enhance the action of TRAIL and allow it to overcome protection caused by overexpression of Bcl-2. This effect is not associated with enhancement of early steps of TRAIL-dependent apoptosis leading to activation of caspase-8 and Bid protein. The inactivation of Bcl-2 also does not define the effect of cytoskeleton inhibitors. It is supposed that destruction of cytoskeleton alters the mechanism of the TRAIL- (or TNF)-dependent cytochrome c release from mitochondria by making it resistant to Bcl-2. The combined use of cytoskeleton inhibitors, which are antitumor drugs, with the recombinant TRAIL preparations may be efficient in therapy of tumors resistant to traditional chemotherapy.

[Human large intestine adenocarcinoma cells (CaCo-2) in the process of cultivation].

Using cytomorphometry and cytophotometry cells of human large intestine adenocarcinoma (CaCo-2) were studied under condition of a 10 day cultivation. A reverse dependence was established between proliferative activity and monolayer density. The increase of the latter inhibits proliferation and promotes the formation of islets of polymorph cells. 2c-cells could be seen only at the beginning of culture growth; a larger part of cells polyploidized by cell blocking in G2-phase. These cells do not divide, which is testified by the absence of 2c-cells, but some part of 4c-cells start the next cycle, accumulates 8c-DNA and then divides, replenishing the 4c-cells population. In the process of cultivation, we observed an increase in the number and total volume of nucleoli in the nuclei, and a rise in DNA amount in the peri-nucleolar chromatin. The formation of numerous 4c-cells with multi-nucleolar nuclei may define an increase of functional activity of CaCo-2 culture as the whole, whereas the formation of separated groups of such cells in the monolayer may denote a possible initiation of their differentiation.

Biochemical characterization of human enteropeptidase light chain.

The synthetic gene encoding human enteropeptidase light chain (L-HEP) was cloned into plasmid pET-32a downstream from the gene of fusion partner thioredoxin immediately after the DNA sequence encoding the enteropeptidase recognition site. The fusion protein thioredoxin (Trx)/L-HEP was expressed in Escherichia coli BL21(DE3). Autocatalytic cleavage of the fusion protein and activation of recombinant L-HEP were achieved by solubilization of inclusion bodies and refolding of Trx/L-HEP fusion protein. The kinetic parameters of human and bovine enteropeptidases in the presence of different concentrations of Ca2+ and Na+ for cleavage of the specific substrate GD4K-na and nonspecific substrates such as small ester Z-Lys-SBzl and chromogenic substrates Z-Ala-X-Arg-pNA have been comparatively analyzed. It is demonstrated that positively charged ions increased the Michaelis constant (Km) for cleavage of specific substrate GD4K-na, while the catalytic constant (k(cat)) remained practically unchanged. L-HEP demonstrated secondary specificity to the chromogenic substrate Z-Ala-Phe-Arg-pNA with k(cat)/Km 260 mM(-1) x sec(-1). Enzymatic activity of L-HEP was suppressed by inhibitors of trypsin-like and cysteine (E-64), but not metallo-, amino-, or chymotrypsin-like proteinases. L-HEP was active over a broad range of pH (6-9) with optimum activity at pH 7.5, and it demonstrated high stability to different denaturing agents.

[Behavior of HEp-2 cell line cells, their nuclei and nucleoli during cultivation and under the effect of Na-ds-RNA]. / Povedenie kletok perevivaemoi kul'tury HEp-2, ikh iader i iadryshek v protsesse kul'tivirovaniia i pod deistviem Na-ds-RNK.

The behavior of human larynx cancer cells (HEp-2) and of their nuclei and nucleoli during the cultivation without the influence of Na-ds-RNA and after its introduction into the medium was investigated by methods of cytomorphometry and cytophotometry. The density of monolayer (the number of cells on the area unit), percentage of two-nuclear cells, the number of nucleoli in the nuclei, mitotic coefficient, volume and total surface of nuclei and nucleoli have been measured. In addition, the mass of DNA in the nuclei and that of the total RNA and DNA in the nuclei and in each nucleolus was measured. Cells in the culture, not subjected to the influence of Na-ds-RNA, were weakly differentiated, kept active proliferation, and their population contained a small number of two-nuclear elements and a high share of multi-nuclear cell. During cultivation, these indices became even more pronounced, which is typical for the increase in cell malignancy. Under the influence of Na-ds-RNA, the proliferate activity decreases, the number of double-nuclear cells increases, while that of multi-nucleolar cell decreases; also, the share of cells with one- and two-nucleolar nuclei increases. The authors conclude that Na-ds-RNA may have antineoplastic activities, clearly evidenced from its influence on the culture of transformed HEp-2 cells.

Identification and characterization of an 18-kilodalton, VAMP-like protein in suspension-cultured carrot cells.

Polyclonal antibodies raised against rat vesicle associated membrane protein-2 (VAMP-2) recognized, in carrot (Daucus carota) microsomes, two major polypeptides of 18 and 30 kD, respectively. A biochemical separation of intracellular membranes by a sucrose density gradient co-localized the two polypeptides as resident in light, dense microsomes, corresponding to the endoplasmic reticulum-enriched fractions. Purification of coated vesicles allowed us to distinguish the subcellular location of the 18-kD polypeptide from that of 30 kD. The 18-kD polypeptide is present in the non-clathrin-coated vesicle peak. Like other VAMPs, the carrot 18-kD polypeptide is proteolyzed by tetanus toxin after separation of coatomers. Amino acid sequence analysis of peptides obtained by digestion of the 18-kD carrot polypeptide with the endoproteinase Asp-N confirms it to be a member of the VAMP family, as is suggested by its molecular weight, vesicular localization, and toxin-induced cleavage.

The secretory nature of the lesion of carrot cell variant ts11, rescuable by endochitinase.

The carrot cell variant ts11 is unable to form somatic embryos at the non-permissive temperature of 32 degrees C, but the block can be overcome by the addition of a 32-kDa acidic endochitinase to the medium. In this work we conducted a cyto-histological analysis of the blocked embryo forms. The morphology of the endomembrane system is altered; in particular, the ER is dilated and may show electron-dense precipitates and continuity with the plasma membrane. These morphological alterations do not occur in the presence of externally-added endochitinase. We also noticed modifications of the culture medium that are probably related to the morphological observations: the total amount of secreted proteins is reduced and pulse-chase experiments revealed that, compared with wild-type cells, the secretion of major polypeptides is reduced while new minor polypeptides are secreted. Western blot analysis revealed the presence of the binding protein BiP, a resident of the ER and of glutamine synthase, a cytosolic protein, in the medium of ts11 but not wild-type cells. These results indicate that ts11 is altered in the secretory pathway but do not clarify the role of endochitinase.

Na,K-ATPase extracellular surface probed with a monoclonal antibody that enhances ouabain binding.

The Na,K-stimulated ATPase is inhibited by extracellular cardiac glycosides, which bind to the enzyme's alpha subunit. We used a monoclonal antibody, VG4, as a probe of the extracellular surface. The antibody was specific for Na,K-ATPase and bound to intact cells. The epitope was mapped to the first extracellular loop (H1-H2) of alpha, using a combination of techniques including trypsinolysis, N-terminal sequence of a fragment containing the determinant, and analysis of the effects of species-specific sequence differences. The antibody inhibited Na,K-ATPase activity under certain circumstances, indicating that the H1-H2 loop participates in conformational changes that are transmitted to the active site. Mutations in the H1-H2 loop have been shown by others to affect ouabain affinity. Ouabain and the antibody acted synergistically to inhibit the enzyme, which seemingly supported the hypothesis that the H1-H2 loop is an essential part of the cardiac glycoside binding site. Direct measurements of the binding of [3H]ouabain, however, indicated that VG4 enhanced rather than inhibited binding, presumably by promoting favorable conformation changes. The data suggest the possibility that the cardiac glycoside binding site may be intramembrane rather than extracellular.

[The experimental and clinical antitumor action of the interferon inducer larifan]. / Protivoopukholevoe deistvie induktora interferona larifana v éksperimente i klinike.

The paper presents the results of experimental and clinical studies on the antitumor effect of larifan. A statistically significant inhibition of growth of some continuous mouse tumors by larifan in a dose of 2.5 mg/kg given for 5-6 days and by a combination of larifan with an immunomodulator, inosiplex, tested on hepatoma XXIIa which has a rather low sensitivity to larifan. The antitumor effect of larifan may be due to interferon production and immunomodulating effect. Treatment with 0.05% larifan ointment of patients with cervical dysplasia of moderate degree resulted in a significant increase of previously diminished production of alpha-interferon after 10-14 vaginal tampons and clinical cure in 88% of cases. A course of 8-10-day larifan monotherapy given before radial therapy resulted in a considerable improvement in patients with cervical cancer of II-III stages, and subsequently, for 1 1/2-month combined radial therapy, no significant changes in production of alpha-IF were observed. At the same time, in patients with cervical cancer treated by radial therapy alone a significant decrease of alpha-IF production by blood mononuclears was observed by the end of therapy.

[Serological studies of antibodies to Epstein-Barr virus in infectious mononucleosis]. / Serologicheskie issledovaniia antitel k virusu Epshteina-Barr pri infektsionnom mononukleoze

This is the first study in this country of sera from patients with infectious mononucleosis and other infectious diseases (control group) for determination of complement-fixing antibody to the soluble (S) antigen and of fluorescent antibody to the virus capsid antigen (VCA) of Epstein-Barr virus. It was established that the CFT and the immunofluorescence test could be used for diagnosis of infectious mononucleosis only on a limited scale because of the lack of complement-fixing antibody in patients early in the convalescent period and because of the presence of complement-fixing and fluorescent antibody in a high per cent of patients of the control group.