[Synthesis and anti-tumor properties of myelopeptide MP-1].

We have studied anti-tumor properties of bone marrow derived peptide Phe-Leu-Gly-Phe-Pro-Thr (MP-1) synthesized by classical methods. It was shown that MP-1 enhanced the effect ofcytostatic therapy of lymphatic leukemia P388 and increased latent growth period of P388 tumors implanted in irradiated mice. MP-1 also decreased metastasis of mouse breast adenocarcinoma Ca-755 after surgery.

[Synthesis and properties of the myelopeptides with differentiating activity].

The bone marrow myelopeptides Phe-Arg-Pro-Arg-Ile-Met-Thr-Pro (MP-4) and Val-Asp-Pro-Pro (MP-6) have been synthesised by a classical method and by a solid phase synthesis. The differentiating activity of MP-4 and MP-6 in human leukemia cells HL-60 and K-562 has been studied. Both peptides induce terminal differentiation of these cell lines but the mechanism of action of peptides MP-4 and MP-6 is distinguished.

[Myelopeptide MP-5 and fluorescent derivatives: synthesis and biological activity].

The Val-Val-Tyr-Pro-Asp bone marrow peptide (MP-5) and an analogue (MP-5-Lys) were synthesized. Fluorescent derivatives, Ftc-MP-5 and MP-5-Lys(Ftc), were prepared. The biological activity of MP-5 and MP-5-Lys was studied in vitro and in vivo. The MP-5 peptide caused 60-84% inhibition of growth of the following mouse cancers: lymphatic leukemia P-388, melanoma B-16, and cervical carcinoma CUC-5. These peptides also restored functional activity of T lymphocytes that was inhibited by metabolic products of the HL-60 leukemic cell line. MP-5-Lys(Ftc) was shown to preserve the functional properties of MP-5 toward T lymphocytes, but Ftc-MP-5 was practically inactive.

[Enhancement of measles-mumps divaccine using myelopeptide 2 in experiment].

Combined application of mumps and measles vaccine strains in equal doses results in significant decrease of immune response to the former component in humans. It is possible that this phenomenon is related with well-known immunodepressive effect of measles virus, which was demonstrated both in vivo and in vitro. It was previously shown that myelopeptide-2 (MP-2) partially neutralizes suppressive effect of measles vaccine on blast transformation of activated human lymphocytes in vitro. Partial supression of immune response to mumps vaccine by live measles vaccine was reproduced in laboratory animals. It was shown that in experiment MP-2 partially neutralized suppressive effect of measles vaccine.

[Synthesis and properties of the retro-analogue of myelopeptide MP-2].

The bone marrow myelopeptide MP-2 (Leu-Val-Val-Tyr-Pro-Trp), exhibiting antitumor activity, and its retro-analogue (Trp-Pro-Tyr-Val-Val-Leu) were synthesized, and their properties were studied. The in vitro and in vivo activities of retro-MP-2 were comparable with those of MP-2. Both peptides equally restored the functional activity of T-lymphocytes inhibited by toxins released by HL-60 cells and inhibited by 70-82% the growth of various types of transplantable solid tumors: Ca-755 adenocarcinoma of the mammary gland, Lewis adenocarcinoma of the lung, and S180 sarcoma. The positions and intensities of the Cotton effects in CD spectra of the MP-2 peptide and its retro-analogue in various solvents are almost indistinguishable. The positions of extrema and integral intensities of the amide I and amide A bands in IR spectra of both peptides were practically identical. The English version of the paper: Russian Journal of Bioorganic Chemistry, 2005, vol. 31, no. 3; see also http://www.maik.ru.

Induction of differentiation in leukemic cell strains with myelopeptide-4.

We studied the capacity of myelopeptide-4 (regulatory peptide of the bone marrow origin) to induce terminal differentiation of HL-60 and K-562 leukemic cells. Myelopeptide-4 increased the expression of CD14 and CD38 differentiation antigens on the surface of HL-60 cells and of CD44 antigen on K-562 cells, induced the appearance of mature monocyte/macrophages in HL-60 culture and hemoglobin-producing cells in K-562 cell culture, and stimulated phagocytic activity of THP-1 leukemic cells. Myelopeptide-4 is an endogenous factor of cell differentiation, a prospective agent for antileukemic therapy.

[Effect of myelopeptide 2 on the immunization of guinea pigs with live measles vaccine]. / Vliianie mielopeptida 2 na rezul'taty immunizatsii morskikh svinok zhivoi korevoi vaktsinoi.

A model is suggested to study the effects the myelopeptide 2 (MP2) immunomodulator on the results of live measles rash immunized by vaccine. Guinea pigs were found to respond to live measles vaccine L-16 the way man does, i.e. the antibodies' level in their sera was increasing until days 28-56 after a single intramuscular vaccine injection. An intramuscular injection of the MP2 immunomodular, made alongside with vaccination, was demonstrated to enhance the immune response to the measles vaccine and to induce its action. Finally, it was for the first time, that the possibility was proven to enhance the action of the live measles vaccine by an immunomodulator.

[Effect of the SH-group of myelopeptide MP-3 on its macrophage-stimulating activity]. / Vliianie SH-gruppy mielopeptida MP-3 na ego makrofagstimuliruiushchuiu aktivnost'.

Peptide Leu-Val-Cys-Tyr-Pro-Gln, identical to the bone marrow peptide MP-3, and its Val3 and Ser3 analogs, lacking SH-group, were synthesized by conventional methods of peptide chemistry in solution and, along with the MP-3 S-S-dimerization product, were studied with respect to their effect on the macrophage phagocytic activity. It was shown that the activity was only enhanced by peptide MP-3, which demonstrated the essential role of the SH-group in this function. The dimer analog of MP-3, unlike dimer analogs of other monocysteine-containing peptides, glutathione and HP5b, did not exhibit the inhibitory effect.

A new endogenous differentiating factor (myelopeptide-4) for myeloid cells.

Along with known lymphokines involved in the regulation of hematopoiesis, a new differentiating factor (myelopeptide-4, MP-4) for myeloid cells was found. The peptide (Phe-Arg-Pro-Arg-Ile-Met-Thr-Pro) originally isolated from the culture medium of porcine bone marrow cell culture was examined for its ability to induce differentiation in two human myeloid leukemia cell lines, HL-60 and K-562. Agents with well-known differentiation-inducing activity, such as phorbol myristate acetate, dimethylsulfoxide and the lymphokines were used as a reference. It has been shown that MP-4 significantly influences the integral characteristics of metabolism, expression of surface antigens and morphology of these cells. It decreased the level of chromosomal DNA synthesis and, in parallel, increased the total protein synthesis in both HL-60 and K-562 cells. MP-4 induced the expression of CD14 monocyte-specific surface antigen and the appearance of mature monocytes/macrophages in HL-60 cell cultures. There was a good correlation of cell metabolic/morphological changes and the CD14 marker expression for HL-60 cells. A similar phenomenon was observed in K-562 cells treated with MP-4 when the levels of hemoglobin synthesis were detected in their cytoplasm. Thus, we consider MP-4 as a new endogenous differentiating factor for myeloid cells.

[Endogenous immunoregulatory peptides (myelopeptides): structure, function, and mechanism of action]. / Endogennye immunoreguliatornye peptidy (mielopeptidy): struktura, funktsiia, mekhanizm deistviia.

Previously unknown bioregulators from bone marrow, myelopeptides, were isolated, identified, and synthesized, and their biological properties and mechanism of action were studied in detail. Phe-Leu-Gly-Phe-Pro-Thr (MP-1) manifests an immunocorrecting effect by restoring the level of antibody production in animals suffering from immunodeficiencies of various etiologies; Leu-Val-Val-Tyr-Pro-Trp (MP-2) manifests an antitumor effect by abolishing the inhibitory action of tumor cells on the functional activity of T-lymphocytes; Leu-Val-Cys-Tyr-Pro-Gln (MP-3) stimulates phagocytosis by macrophages and, in this way, protects animals from infections caused by pathogenic microorganisms; and Phe-Pro-Arg-Ile-Met-Thr-Pro (MP-4) is a new factor of cell differentiation inducing terminal cell differentiation in the HL-60 and K-562 leukemic cell lines.

[Myelopeptides: isolation and structure]. / Mielopeptidy: vydelenie i struktura.

A new method was developed for the isolation of biologically active peptides present in small quantities in supernatants of bone marrow cell cultures. Four new peptides, which exhibited immunostimulating and differentiating activities, were isolated from the supernatant using solid phase extraction and reversed-phase HPLC. For these peptides, the following primary structures were elucidated: Leu-Val-Cys-Tyr-Pro-Gln, Phe-Arg-Pro-Arg-Ile-Met-Thr-Pro, Val-Val-Tyr-Pro-Asp, and Val-Asp-Pro-Pro.

Bone marrow immunoregulatory peptides (myelopeptides): isolation, structure, and functional activity.

Myelopeptides (MPs) are bioregulatory mediators of bone marrow origin. Several individual MPs have been isolated from the supernatant of porcine bone marrow cell culture by successive solid phase extraction and reversed-phase high performance liquid chromatography. Two of them, MP-1 (Phe-Leu-Gly-Phe-Pro-Thr) and MP-2 (Leu-Val-Val-Tyr-Pro-Trp), were synthesized and their biological activities were comprehensively studied. Both hexapeptides display pronounced immunoregulatory activity but their final effects as well as mechanisms of action are different. Peptides MP-1 and MP-2 are identical to conservative fragments 33-38 alpha- and 31-36 beta-chains of hemoglobin, respectively. The sequences of other isolated MPs have no homology with any functional protein. The role of MPs in bioregulatory processes in vivo is discussed.

The bone marrow peptide (myelopeptide-2) abolishes induced by human leukemia HL-60 cell suppression of T lymphocytes.

Myelopeptide-2 (MP-2) Leu-Val-Val-Tyr-Pro-Trp originally isolated from the supernatant of porcine bone marrow cell culture was examined for its capacity to restore the mitogen responsiveness of human T lymphocytes inhibited by conditioned media from HL-60 leukemia cells (HL-60 CM). MP-2 added to phytohemagglutinin (PHA)-stimulated T lymphocytes together with HL-60 CM abolished the suppression of T-lymphocyte proliferative response in a dose-dependent manner. Another bone marrow hexapeptide Phe-Leu-Gly-Phe-Pro-Thr, MP-1, did not display this action in that experimental system. MP-2 was also effective being added after T-lymphocyte exposure to HL-60 CM which suggests its recovery but not protective effect on T-lymphocytes treated with tumor cell products. Flow cytometry analysis revealed HL-60 CM influence on the expression of CD3 and CD4 T-cell surface antigens. It decreased the content of CD3- and CD4-positive cells and induced the appearance of T lymphocytes with reduced density of CD3 and CD4 antigens. MP-2 was able to restore the T-cell phenotype altered by HL-60 CM. MP-2 seems to be promising in anti-tumor therapy.

Myelopeptides: bone marrow regulatory mediators.

Bone marrow cells of various animal species and men produce a group of bioregulatory peptides called myelopeptides (MPs). A highly purified MP fraction and some individual molecules have been isolated from the supernatant of porcine bone marrow cell cultures by reverse phase chromatography. MPs have a wide spectrum of functional activities: immunoregulatory, differentiating and opiate-like. They evoke 2.5-fold stimulation of antibody production to various antigens. They correct some immune defects in MRL/lpr mice with spontaneous autoimmune disorders that results in 2-fold prolongation of the life span of these mice. MPs influence the differentiation of bone marrow and peripheral blood cells derived from healthy and leukemic donors. They induce terminal differentiation in the leukemic human HL-60 cell line. MPs also show an effect on pain sensitivity. A new immunocorrective drug Myelopid has been developed on the basis of MP mixtures. This drug is effectively used in Russia both in medicine and veterinary practice for prophylaxis and treatment of diseases accompanied by immunodeficiency. Two individual MPs were isolated and identified: Phe-Leu-Gly-Phe-Pro-Thr (MP-1) and Leu-Val-Val-Tyr-Pro-Trp (MP-2). MP-1 displays immunoregulatory activity; MP-2 abolishes the inhibitory effect of leukemic cells on T-lymphocyte functional activity. MPs seem to provide not only immunoregulation but also to participate in complex interactions between different systems in the organism.