Biomedical subjects
Publications and source records attributed to V F Chekhun.
Olivomycin (DNA-binding antibiotic) in nanomolar concentrations induces apoptosis of human tumor cells and inhibits p53-dependent transcription of the reporter gene (basal and induced by antitumor drugs). Olivomycin aglycon induces no cytotoxicity and does not block transcription.
AIM: To study the expression of proteins that characterize drug resistance, proliferation and apoptosis of human ovarian carcinoma cells. METHODS: The study was carried out on human ovarian carcinoma A2780 cells and on the A2780/DDP8 subline resistant to cisplatin. Expression of the surface and intracellular antigens (p53, Bcl-2, CD95, antigen of proliferating cells, metallothioneins, drug resistance proteins (P-glycoprotein (P-gp), glutathione-S-transferase), molecules of adhesion (E-cadherin, alpha- and beta-catenins) was studied by immunocytochemical method. RESULTS: It has been shown that the formation of the resistance to cisplatin in A2780/DDP8 cells is accompanied by the increase of expression of glutathione-S-transferase and Bcl-2, by the decrease of expression of CD95-antigene and proliferation potential of the cells, by appearance of EGF receptors and elevation of expression level of E-cadherin, alpha- and beta-catenins, proving the enhancement of adhesive properties of tumor cells. CONCLUSION: Antiapoptotic program seems to be the leading mechanism of the development of the resistance to cisplatin in A2780/DDP8 cells and is realized via high expression of Bcl-2. During the development of drug resistance of A2780/DDP cells, the program of glutathione detoxification is functionally replacing the decrease of the content of metallothioneins.
UNLABELLED: The aim of the study was to evaluate the total proteolytic activity (TPA) and the content of alpha-1-proteinase inhibitor (alpha1PI) and alpha-2-macroblobulin (alpha2M) in the blood plasma of mice with Lewis lung carcinoma (LLC) upon the development of resistance to cisplatin. METHODS: Experimental LLC model with different sensitivity to cisplatin was obtained by sequential subcutaneous transplantation of LLC cells from cisplatin-treated animals. TPA, alpha1PI and alpha2M levels were evaluated by standard biochemical methods. RESULTS: It has been shown that the development of LLC resistance to cisplatin is accompanied by the increase of TPA activity and the level of the main proteinase inhibitor - alpha1PI. Despite the high level of alpha1PI in the resistant variant of LLC compared to parental tumor, the increase of TPA/alpha1PI ratio indicated the deficiency of that inhibitor in the blood of mice bearing cisplatin-resistant tumors, that promotes metastasis. The growth of both resistant to cisplatin LLC and sensitive variant was accompanied with the reduction of the alpha2M concentration. CONCLUSIONS: Upon the development of resistance to cisplatin in vivo the shift in the balance between proteinases and their inhibitors toward activation of TPA simultaneously with the increased metastasis is taking place.
Immunization of adult animals with the Ehrlich ascytic cancer cells homogenate three months prior to an experiment, did not affect either tumor transplantation or the progress of cancerogenesis induced by injection of 20-methylcholanthrene oil solution into the femoral muscle. All consequences of adult animal vaccination disappeared in 30-40 days following antigen administration. Quite different consequences were observed after immunization of the newborn mice. The same antigen (Ehrlich cancer cells homogenate) injected to newborn mice on days 1 and 3 after birth in a dose that failed to develop tolerance not only significantly increased the ascytic tumor transplantation threshold (by nearly 200 times for sarcoma 37 cells and by nearly 400 times for Ehrlich cancer cells) in adult animals but also led to almost 50% inhibition of cancerogenesis (induced by injection of 20-methylcholanthrene oil solution in the femoral muscle of mature mouse) after three and even after 12 months following immunization. The MTT-analysis did not reveal any noticeable differences in the number and activity of the cytotoxic lymphocytes in populations of splenocytes obtained from the intact mice (control) and from the adult animals which had been exposed to postnatal immunization (experiment).However, after a new vaccination such differences were found. In the populations of splenocytes obtained from control animals, the cytotoxic activity measured on day 10 after vaccination had increased 2.86-fold mainly at the expense of an increased number of effector cells. In the populations of splenocytes obtained from the experimental group of animals the activation was much greater (25.8-fold), being accomplished not only at the expense of an increased number of the effector cells, as observed in the control group, but also at the expense of their higher activity. The kinetic analysis of a mechanism of effector cells/target cells interaction has led to derive equations for estimation of the limiting rates of such interaction and of the equilibrium constants for interacting cells. Analysis of a generally accepted mechanism of the cytotoxic lymphocytes formation, with an account of the kinetic analysis data, has shown that a major reason of low antitumor resistance of animal organism is the negligible population of resting cells--the precursors of antitumor cytotoxic lymphocytes. Newborn mice vaccination does not produce any increase in the number of resting cells of the necessary type. This circumstance explains both, increase of the ascytic tumor transplantation threshold and increase of the resistance to 20-methylcholanthrene action in adulthood. Adult animal immunization does not possess such action. Analysis of the problem leads to the conclusion that the system of organism's antitumor resistance becomes effective only in those cases when, owing to antigen activation of resting cells, the concentration of cytotoxic lymphocytes rises to such an extent that the rate of tumor cell destruction becomes greater than the rate of target cells reproduction.
It is known that tumour progression towards drug resistance is one of the main factors resulting in the failure of cancer treatment. As tumour progression is based on the genetic instability, the study of the structure of nucleic acid from tumour cells is of great importance both for basic knowledge and for biomedical application. We applied surface enhanced infrared absorption spectroscopy (SEIRA) of nucleic acids on gold substrate and essentially increased the sensitivity of IR spectroscopy. We observed numerous changes in infrared spectra of DNA from sensitive and resistant cells that reflect drastic changes in molecular structure of DNA from tumour cells. The DNA from resistant cancer cells could be characterised as rigid structure, the structure of DNA from sensitive cancer strain seems to be flexible and after application of anticancer drugs drastically changes and approaches to the structure of helix forms. The molecular structure of lipids from resistant and sensitive cancers after application of anti-tumour drugs is also modified. Thus, we observed a disordering in the lipid chain packing from resistant cells after application of cisplatin and, in some cases, formation of phospholipid-Pt complex.
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Murine L1210 leukemia cells possessing an increased resistance to cisplatin were found to be refractory to transforming growth factor (TGF)-beta1-induced growth inhibition, while the parental L1210 cells were strongly inhibited by this cytokine. Growth inhibition was estimated on the basis of [3H]thymidine incorporation, cell counting and colony-forming assay. Cisplatin-resistant L1210 cells were also shown to be much more resistant than the parental cells to both cisplatin- and TGF-beta1-induced apoptosis. These results suggest the existence of cross-resistance to cisplatin and TGF-beta1 in the studied leukemia cells.
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The toxic and antitumor effects of cisplatin were shown to depend upon the activity of microsomal oxidation system enzymes. Administration of the drug in combination with K-2-9 enterosorbent was followed by an increase in its antitumor effect and amelioration of toxicity.
The K-2-9 preparation was determined to change cis-platinum pharmacokinetics, that resulted in its pharmacodynamics alterations. The higher Pt concentrations in the blood of animals which were given the K-2-9 preparation provided selectivity of cytostatic accumulation in the tumour tissue, that was accompanied by more prolonged inhibition of the DNA synthesis. A decrease in the toxicity of cis-platinum is associated with a change in the elimination pathway and acceleration of its removal from the organism.
The effect of complex-forming sorbent K-2-9 on cisplatin toxicity was studied experimentally. Simultaneous treatment with the preparations was shown to lower the nephro- and gastroenterotoxicity of cisplatin did not detract from the antitumor effect of cisplatin.
The effect of interferon (IF) on the activity of multipurpose hepatic oxidases (MHO) in animals in the process of metastatic tumour development as well as interaction of IF and vinblastine (VBL) in the cell culture have been studied. IF activates MHO under conditions of their inhibition at the beginning of the tumour development and inhibits them to the normal level under activation in the postmetastatic period. Contrary to the data obtained in vivo IF does not decrease the toxicity of VBL for the tumour cells in vitro. The data obtained evidence for the modulating effect of IF on the MHO system under the tumour development.
Modifications of the main quantitative characteristics of experimental tumour processes are proposed for the optimal assessment and comparison of various antitumoural effects.
It is established that the preparation K-2-9 being administered in combination with cis-dichlorodiaminoplatinum (DDP) lowers the DDP toxic effects, in particular nephrotoxicity and enterotoxicity, increases the activity of the enzymes participating in microsomal liver oxidation, the activity of kidney transamidinase, the quantity of SH-groups of the liver and kidney tissue, intensifies the antitumour effect of DDP.
A combined administration of cis-dichlorodiaminoplatinum (DDP) and phenobarbital increases the activity of nonspecific oxidases, decreases the toxic effect of DDP especially its nephrotoxic action, but does not decrease the antiblastic action of DDP in rats. On the basis of experimental data the optimum regime of DDP repeated administrations is suggested.
The correlation between the tumor drug sensitivity and the degree of lymphocyte interphase nuclei chromatin damages induced by cisplatin in rats was found using sensitive and resistant to cisplatin variants of Guerin's carcinoma. Increased optical density of lymphocyte chromatin in first minutes after cisplatin injection both in rats without Guerin's carcinoma and with sensitive to cisplatin variants of this tumor was observed. Lymphocyte chromatin structure remains unchanged in rats with cisplatin resistant carcinoma. Normal blood cells are suppose to change their sensitiveness to cisplatin under the humoral influence of the growing tumor in according with its phenotype.
Examined in treating rats with Guerin's carcinoma with doxorubicin was the possibility that the polyenzymic drug preparation wobe-mugos E had hepatoprotective, cardioprotective and myeloprotective effects. In intramuscular administration wobe-mugos E has not been found to stimulate the tumour growth, it exhibited a manifest hepatoprotective and myeloprotective actions with respect to adverse reactions of doxorubicin but failed to diminish cardiotoxicity of the latter. The protective effect of the above polyenzymic drug was of a dose-dependent character.
Computer modelling is used to study interactions between polyamines and nuclear transcription factor NF-kappa B and NF-kappa B. specific DNA complex. It is shown that polyamines can regulate interaction between NF-kappa B and the specific DNA sequence by binding to p50 subunit of NF-kappa B. A possible polyamines binding site on the surface of p50 is found. Dissociation of polyamines to p50.DNA complex is modelled. Kd of spermine, spermidine and putrescine are calculated. Conformational transition of DNA.(p50)2-->DNA.p50 + p50 is simulated. Kd of complex p50.DNA is calculated in the presence and in the absence of polyamine in the binding site on the p50. It is shown that polyamines stabilizes the inter-domain interface of p50 protein due to appearance of additional electrostatic and hydrogen bonds. Shah, Thomas and Shirahata obtained the following sequence of efficiency in facilitating NF-kappa B--DNA binding: spermine > spermidine > putrescine. The sequence of affinities of polyamines to NF-kappa B that we obtained corresponds well to the former sequence from the cited work. Our results support the hypothesis that polyamines decreases the probability of spontaneous dissociation of DNA.p50 complex.