492
Bulletin of Experimental Biology and Medicine, Vol. 154, No. 4, February, 2013
ONCOLOGY Effects of Nonstarch Polysaccharides with Different Molecular Weights on the Development of Lewis Lung Carcinoma in Mice and Efficiency of Cytostatic Therapy
O. Yu. Rybalkina, T. G. Razina, K. A. Lopatina, E. N. Amosova, S. G. Krylova, L. A. Efimova, E. A. Safonova, E. P. Zueva, M. Yu. Khotimchenko*, and Yu. S. Khotimchenko**
Translated from Byulleten’ Eksperimental’noi Biologii i Meditsiny, Vol. 154, No. 10, pp. 488-493, October, 2012 Original article submitted April 9, 2011 The effects of nonstarch polysaccharides with different molecular weights on the development of Lewis’ lung carcinoma and efficiency of cyclophosphamide therapy in mice were studied. Treatment with these substances with low molecular weights (400 kDa) inhibited the growth of Lewis’ lung carcinoma node. Antimetastatic effects of cyclophosphamide were stimulated by low and high molecular weight polysaccharides. Key Words: nonstarch polysaccharides; molecular weight; chemotherapy Despite the progress in development of new therapeutic methods for the treatment of tumor diseases, specifically, target therapy, making use of monoclonal antibodies, the treatment of cancer patients remains a serious problem. The main causes of difficulties are immunogenic activity of drugs, heterogeneity of the tumors, and stimulation of autoimmune reactions. That is why the classical chemotherapy is going to remain the base of drug therapy of this patient population for a long time. However, cytostatic therapy is not a guarantee of cure and does not rule out the development of relapses and metastases. Injections of maximally tolerable doses of antitumor drugs for as complete Institute of Pharmacology, Siberian Division of the Russian Academy of Medical Sciences, Tomsk; *A. V. Zhirmunsky Institute of Marine Biology, Far Eastern Division of the Russian Academy of Sciences; **School of Biomedicine, Far Eastern Federal University, Vladivostok, Russia. Address for correspondence:
[email protected]. O. Yu. Rybalkina
as possible suppression of tumor growth leads to the development of cytostatic disease and damage to the rapidly regenerating cell systems. Many drugs reducing the toxicity of cytostatic therapy are available today: polyoxidonium, leukinferon, galavite, glutoxim, betaleukin, derinat, neupogen. However, there are no drugs stimulating the efficiency of chemotherapy. Experimental findings indicate that plant extracts and bioactive substances derived from plants (Acorus calamus polysaccharides, extracts from eleuterococcus, Scutellaria baikalensis, Hippophae stem and bark, etc.) improve the efficiency and reduce the toxicity of cytostatic therapy [1] and can therefore be added to therapeutic protocols for patients with tumors. Modifiers of biological activity are assumed to stimulate the efficiency of antitumor therapy. This group of drugs includes substances of plant origin active towards tumor cells and towards the regulatory systems. Nonstarch polysaccharides (alimentary
0007-4888/13/15440492 © 2013 Springer Science+Business Media New York
O. Yu. Rybalkina, T. G. Razina, et al.
493
MATERIALS AND METHODS
fibers) are promising in this respect. As a rule, they are nontoxic and characterized by a wide spectrum of pharmacological activity and differ from chemical drugs by less complex technology of isolation and purification [3]. Nonstarch polysaccharides, isolated from plants, are characterized by a variety of the lateral structures, block structure of molecules; these features determine their biological effects [3]. Relationship between polysaccharide structure and their pharmacological effects, specifically, antitumor activity, has been described [8]. We studied nonstarch polysaccharides with different molecular weights. Their chemical composition included acid (galacturonic, mannuronic, etc.) sugar residues. Pectins are structural elements of the cell wall in higher terrestrial and water plants. Their main carbohydrate chain is made of D-galacturonic acid α-1,4-bound residues. Alginates belong to the family of nonramified binary copolymers consisting of β-Dmannuronic and α-L-guluronic acids connected via (14)-bonds. The proportion and sequence of acid residues vary depending on their source and method of derivation [4]. Alginic acid and its salts are present in sea algae, brown (Pheophyta) and red (Corallinaceae). In addition, Pseudomonas and Azotobacter bacteria contain acetylated alginates. Commercial pectins and alginates are used in food industry as thickening agents and stabilizers. Antibacterial, antiviral, anticlotting, hypolipidemic, and other effects of polysaccharides are described [11]. They modify the immune system by modulating the neutrophil and macrophage activities, stimulating T cells, inducing the production of some cytokines [2,14]. We studied the effects of nonstarch polysaccharides with different molecular weights on the development of Lewis’ lung carcinoma (LLC) and efficiency of cyclophosphamide therapy in mice.
Experiments were carried out on 315 females C57Bl/6 mice (19-26 g; 2-3 months). First-category animals were obtained from Department of Experimental Biosimulation, Institute of Pharmacology (Quality Certificate No. 188-05). The animals were kept and handled in accordance with the regulations of the European Convention for Protection of Vertebrate Animals Used for Experimental and Other Scientific Purposes [8]. Experiments were carried out in accordance with the Guidelines for Laboratory Practice (GLP), Order No. 267 of the Ministry of Health of the Russian Federation of June 19, 2003 “On Validation of Laboratory Practice Regulations”, Federal Law “On Drugs” (article 36), and Manual of Experimental (Preclinical) Studies of New Pharmacological Substances (Moscow, 2005). The experiment design was approved by the Ethic Committee of Institute of Pharmacology. Specimens of nonstarch polysaccharides obtained by an original method of chemical hydrolysis of natural polysaccharides and standardized by physicochemical characteristics were a gift from Laboratory of Pharmacology, A. V. Zhirmunsky Institute of Marine Biology. Specimens of nonstarch polysaccharides differed by molecular weights, content of sodium and uronic acids (Table 1). Lewis’ lung carcinoma was transplanted intramuscularly (5×106 cells in 0.1 ml 0.9% NaCl) [5]. The studied substances were dissolved in distilled water and administered intragastrically to mice in doses of 50 and 100 mg/kg daily starting from day 7 after tumor transplantation. Cyclophosphamide was injected in a single intraperitoneal dose of 125 mg/kg on day 10 after LLC transplantation. Controls received an equivalent volume of distilled water intragastrically
TABLE 1. Physicochemical Parameters of the Studied Nonstarch Polysaccharides Specimen
Parameter
Sodium content, %
pectin
sodium alginate
acid-insoluble sodium alginate hydrolysate
acid soluble ethanolprecipitated sodium alginate hydrolysate
(400 kDa)
(10-20 kDa)
(
