[The lysosomal cathepsins B, L and D in development of murine experimental leukemias].

Lysosomal proteases are actively involved in pathogenesis of cancer progression. Alterations in proteases and their inhibitors interaction were suggested to be implicated in the processes of tumor invasion and metastasis. Among proteases connected with malignant growth, cysteine cathepsins B and L and aspartic cathepsin D play the main role in the tumor development. The present study was designed to investigate activity of cathepsins B, L and D activity in the development and treatment of murine experimental leukemias and to determine the correlation of these proteases with tumor malignancy and the chemotherapy effect. P-388 leukemia was characterized by a more aggressive development and unfavorable prognosis than L1210/1 leukemia. The activity of cathepsins B, L and D in tumor tissues of mice infected with P-388 leukemia, as well as in liver and spleen and the activity of cathepsins B and L in serum were lower than their activity in mice infected with L1210/1 leukemia. Changes of cathepsin activity in liver and spleen of mice with leukemias have demonstrated a level of aggressiveness of tumor development and invasion of liver and spleen by neoplastic cells. The treatment resulted in the increase of cathepsin B, L and D activities in tumor tissue, liver, spleen and cathepsin B and L activities in serum. The highest activity of proteases was revealed in the groups of mice characterized by the greatest suppression of tumor growth. These data have shown that lysosomal proteases are involved in progression of murine experimental leukemias and elimination of tumor cells in the result of treatment. Determination of the activity of cysteine and aspartic proteases can be used for evaluation of cancer diseases malignancy, their sensitivity for chemotherapy and efficiency of treatment.

[Cystatins: cysteine proteases regulation and disturbances in tumors and inflammation].

Cystatin C belongs to the group of wide spread extracellular cysteine protease inhibitors. Using ELISA kits it was shown that the highest cystatin C concentration was in human cerebrospinal fluid and low cystatin C concentration was in human urine. In healthy young persons serum cystatin C concentration was lower than in elder patients (50-65 year old). In patients with hemoblastoses (lymphoma, lymphogranulomatosis) increased serum cystatin C concentration was normalized after effective antitumor therapy. According to these data one can conclude that serum cystatin C concentration can be used as one of the prognostic criteria in patients with several kinds of hemoblastoses.

[Effect of biological response modifier sulfoethylated (1 --> 3)-beta-D-glycan on the experimental leukemia in mice].

Sulfoethylated (1 --> 3)-beta-D-glycan (SE-glycan) is a well-known biological response modifier, which activates the immune system via the influence on macrophages and lymphocytes. In these experiments, SE-glycan suppressed the growth of solid transplants of leukemias P-388 and L1210/1 in mice and, when combined with cyclophosphamide, significantly potentiated its action. The administration of SE-glycan allowed the cyclophosphamide dose to be reduced by half without negatively influencing the curative effect. The proposed treatment also led to an increase in the activity of lysosomal proteases (cathepsins B, L and D) in tumor tissues. The extent of changes was in direct relation to the therapeutic effect.

Enhancing effect of new biological response modifier sulfoethylated (1-->3)-beta-D-glucan on antitumor activity of cyclophosphamide in the treatment of experimental murine leukoses.

AIM: One of the advanced methodologies of the tumor therapy is the application of the so-called biological response modifiers used for activation of the endogenous antitumor mechanisms and combined with classical cytotoxic agents. The aim of this work was the investigation of the effect of sulfoethylated (1-->3)-beta-D-glucan (SEG) in the treatment of experimental murine leukoses in combination with cyclophosphamide (CPA) and its ability to modulate the activity of lysosomal enzymes in tumor tissues. MATERIALS AND METHODS: The solid forms of inoculated murine leukoses P388 and L1210/1 were transplantated to male DBA/2 mice. The therapy was performed by treating animals with CPA (Biokhimik, Saransk, Russia) alone or in combination with SEG (Institute of Chemistry, Slovak Academy of Sciences, Slovakia). CPA was administered in saline as a single intraperitoneal (ip) injection on the 10th day after tumor transplantation; SEG was administered to mice ip 3 days after tumor transplantation with the intervals in 3 days. The therapy effect was estimated by measuring of solid tumor volume. Activity of the cysteine proteases--cathepsins B and L--was measured fluorometrically using fluorescent substrates Z-Arg-Arg-MCA and Z-Phe-Arg-MCA (Sigma, USA), respectively. The apoptosis was estimated evaluating the number of cells with fragmented nuclei using optical microscope. RESULTS: It has been demonstrated that application SEG leads to inhibition of tumor growth and potentiates therapeutic action of CPA, especially at repeated administrations during the whole treatment/observation At addition of SEG, therapeutic effect of a one-half reduced dose of CPA is equal or higher than that of the full dose. Therapeutic action of CPA and SEG on the studied tumors is realized predominantly through induction of apoptosis and is accompanied by a substantial increase of the activity of cysteine proteases cathepsins B and L in tumor tissues. The highest cathepsin B and cathepsin L activity in tumor tissue accompanied with the strongest inhibition of tumor growth. It is suggested that this phenomenon is due to the infiltration of the macrophages rich in the named enzymes into the tumor, where they phagocytize the apoptotic cells and tissue debris. CONCLUSION: Utilization of this polysaccharide BRM, sulfoethylated (1-->3)-beta-D-glucan, might potentially enhance efficiency of antitumor therapy with standard cytostatics without a need of substantial increase of their dosage and hence avoiding their toxic side-effects.