[Apoptosis-reactivating agents for targeted anticancer therapy].

The current knowledge on molecular mechanisms of apoptosis is presented focusing on the key elements of the extrinsic death receptor pathway as well as the intrinsic mitochondrial pathway. Disregulation of apoptotic pathways is considered as a key factor in the survival of cancer cells in response to conventional chemotherapeutic drugs or radiation therapy. Substances that selectively reactivate apoptosis in malignant cells are the promising candidate anticancer drugs, which have now entered various phases of clinical trials. The up-to-date techniques allowing for non-invasive in vivo visualization of apoptotic cells with special reference to therapy-induced cell death are briefly surveyed.

[Detection of early apoptotic changes in cells in vitro using nuclear magnetic resonance spectroscopy].

The technique of proton magnetic resonance spectroscopy (1H MRS) was used as the sensitive express method for early specific detection of the apoptotic cells. The technique allows recognition of the changes in signal intensities corresponding to methylene (CH2) and methyl (CH3) protons of the mobile lipid domains (MLD) and choline, which are characteristic of apoptotic rather than of necrotic cells. A strong linear correlation between MLD content (calculated as CH2/CH3 signal intensity ratio) and the number of apoptotic cells in Namalwa or MT4 cell lines has been shown for any inducer of apoptosis used in the study. MLD content estimated by 1H MRS technique correlated significantly with apoptotic cells numbers (r = 0.992) recorded by conventional techniques. The increase in MLD content was registered as early as 60 min after the addition of etoposide coinciding with the time course of caspase-3 activation.

[Apoptosis of human malignant lymphoid NAMALWA cells induced by resveratrol and quercetin].

The effects of naturally-occuring polyphenols, resveratrol and quercetin, on cell viability and apoptosis were studied in Namalwa B-cell lymphoma line. Apoptotic cells were identified using DNA flow cytometric analysis and 1H NMR spectroscopy. The effects of the agents on the cell cycle kinetics and activation of caspase-3 were examined. Both resveratrol and quercetin induced apoptosis in Namalwa cells as demonstrated by the increased number of hypodiploid cells, elevated level of mobile lipid domains and caspase-3 activation. Treatment with 40 microM of resveratrol for 48 h resulted in time-dependent cell-cycle arrest at G0/G1. In contrast, upon quercetin treatment Namalwa cells accumulated in G2/M. Obtained results suggest that resveratrol and quercetin induced caspase-dependent apoptosis in human malignant lymphoid cells in vitro. These findings provide a rationale for further studies of in vivo effects of those polyphenols.

Effects of etoposide and fludarabine in subtoxic doses on karyotype of human malignant lymphoid Namalwa cells.

We studied changes in the karyotype of transplanted Namalwa cells induced by DNA-damaging antitumor preparations etoposide and fludarabine in subtoxic doses. The relative number of cells containing increased number of chromosomes and the incidence of chromatid aberrations with primary damage to chromosomes 2, 5, 11, 16, and 17 increased. Cytogenetic changes developed even after short-term incubation of cells with antitumor preparations and were observed during further culturing in a medium not containing etoposide or fludarabine.

[Cytogenetic changes in the Namalwa cell line of human malignant lymphoma induced by inhibitors of DNA replication and synthesis]. / Tsitogeneticheskie izmeneniia v kletkakh perevivaemoi linii Namalwa zlokachestvennoi limfomy cheloveka, indutsirovannye ingibitorami replikatsii i sinteza DNK.

Namalwa cells originating from the malignant human lymphoma have been analyzed cytogenetically upon short-time exposure to subtoxic doses of inhibitors of DNA replication and synthesis, either etoposide or fludarabine. The intact cells were characterized by the modal class of the chromosomes within the diploid range with the proportion of the aberrant cells amounting to 16.0 +/- 0.5%. Upon exposure to etoposide the percentage of the aberrant cells increased amounting to 26.1 +/- 2.9 through 39.8 +/- 1.7% depending on the duration of the exposure and the dose of the drug. At the same time the number of the polyploid cells increased but the modal class retained within the diploid range. Upon exposure to fludarabine the percentage of the cells with the aberrant chromosomes increased to 57.1 +/- 2.9%. Two modal classes appeared--the first approaching the diploid number and the second being polyploid. The exposure to either etoposide or fludarabine resulted in increasing number of the chromatide aberrations with more frequent involvement of #1, #2, #5, #6, #7, #11, #13, #14, #16 and #17 chromosomes. The data obtained have shown the susceptibility of Namalwa cells to the subtoxic concentrations of the inhibitors of DNA synthesis and replication used in the study resulting in the survival of the novel clones resistant to the drugs.

[Apoptosis modulators]. / Apoptomoduliatory.

At least two types of cell death are known: physiological (apoptosis) and pathological (necrosis). Dysregulation of apoptosis plays an important role in the pathogenesis of many pathological conditions. Their analysis gives a key for the development of novel therapeutic approaches. In this review the recent advances and perspectives for clinical use of apoptosis-modulating monoclonal antibodies, low-molecular-weight proteins, peptides, small non-peptide molecules and drugs targeting apoptosis-associated genes are summarized. The rationale for clinical application of apoptomodulators with the aim of increasing efficacy of existing standard therapies are also discussed.

[Apoptosis in myocardial ischemia and reperfusion]. / Apoptoz pri ishemii i reperfuzii miokarda.

Apoptosis initiated in cells of tissues maintaining homeostasis under the influence of growth factors and hormones has been recently described during the early stage of myocardial infarction in the reperfusion zone of the cardiac muscle. Although it has been proved that apoptosis of cardiomyocytes plays one of the key roles in progression of the reperfusion syndrome, molecular and cellular mechanisms of this phenomenon are not yet resolved. Prospects are discussed of a new trend in preventive treatment of ischemic and reperfusion-related affection of the myocardium relying upon blocking of apoptosis of cardiomyocytes.

[Dependence of epidermal growth factor activation on its affinity and oligomerization]. / Zavisimost' aktivatsii retseptora épidermal'nogo faktora rosta ot ego affinnosti i oligomerizatsii.

Epidermal growth factor receptor (EGF-R) oligomerization has been followed on A-431 cells using covalent labeling by 125I-EGF and EGF-dependent autophosphorylation of receptor-kinase. High molecular weight complexes corresponding to monomeric, dimeric, and trimeric forms of EGF-R are detected. The process of oligomerization occurs effectively at 37 degrees C while at 4 degrees C no oligomer formation is detected. PMA or ATP treatment reduces the number of high-affinity EGF-binding sites but has no influence on dimer formation. Dimerisation of the EGF-R in the absence of the ligand has been established on formalin-fixed A-431 cells.

[The effect of epidermal growth factor on protein phosphorylation in normal and transformed hepatocytes]. / Vliianie épidermal'nogo faktora rosta na fosforilirovanie belkov v normal'nykh i transformirovannykh gepatotsitakh.

Qualitative differences in the content of tyrosine-phosphorylated proteins in normal and transformed hepatocytes have been found using the method of two-dimensional electrophoresis. Epidermal growth factor (EGF) has induced quantitative changes in the spectra of phosphotyrosine-containing proteins in normal cells and qualitative changes in the transformed ones. Results of immunoprecipitation with antibodies against phosphotyrosine permit revealing a protein with Mm 50 kDa which is subjected to EGF-dependent tyrosine-phosphorylation in normal hepatocytes. The intensity of protein phosphorylation is 10 times higher in the transformed cells but the dependence of this process on the EGF is not exhibited. The role of protein-tyrosine-kinases in the transmission of a mitogenic signal and in liver carcinogenesis is discussed.

[Changes in the epidermal growth factor receptors in the liver cells of rats in N-nitrosodiethylamine-induced hepatic carcinogenesis]. / Izmenenie retseptorov épidermal'nogo faktora rosta v kletkakh pecheni krys pri gepatokantserogeneze, indutsirovannom N-nitrozodiétilaminom.

A sharp decrease in the number of epidermal growth factor receptors (EGF-R) in the rat liver plasma membranes had been found at different stages of diethylnitrosamine-induced carcinogenesis. The complete loss of high-affinity binding sites for EGF did not prevent EGF-dependent autophosphorylation of EGF-R. Hepatocytes from the rat liver tumors in the primary culture had two classes of EGF-R: high and low affinity ones, though their number had been twice less than in the normal hepatocytes. The dynamics of internalization and down-regulation of EGF-R was very similar in the primary culture of transformed and normal hepatocytes. It testifies that there are some factors of microenvironment in the liver during carcinogenesis which cause the loss of EGF-R (down-regulation) and a decrease of their affinity (activation of protein kinase C). A possible autocrine or paracrine nature of these factors is discussed.

[Increase in the level of polypeptide growth factors and their receptors in induced carcinogenesis and regeneration of the intestinal mucosa in rats]. / Povyshenie urovnia nekotorykh polipeptidnyk faktorov rosta i ikh retseptorov pri indutsirovannom kantserogeneze i regeneratsii slizistoi obolochki kishechnika krys.

It has been established for the first time that in extracts of the regenerating and preneoplastic (4 months after the beginning of carcinogen introduction) intestine as well as in the peritumor tissue the content of EPR-similar polypeptides and insulin raises, whereas in tumours it remains not high. Proteins with molecular weight greater than 120 kD able to compete with 125I-EPR for the binding with the receptors of EPR and being, evidently, the precursors of EPP are found in case of carcinogenesis. Besides, the content of insulin receptors rises, this process being most typical of the large intestine.

[Changes in the contents of epidermal growth factor and EGF-like polypeptides in the liver tissue of rats in N-nitrosodiethylamine-induced hepatocarcinogenesis]. / Izmenenie soderzhaniia épidermal'nogo faktora rosta i podobnykh emu polipeptidov v tkani pecheni krys pri gepatokantserogeneze, indutsirovannom N-nitrozodiétilaminom.

It has been determined that concentration of EGF-like substances in the liver of rats with N-diethylnitrosamine-induced hepatocarcinogenesis increases and reaches its maximum in tumours (50-150 ng/mg protein). In the regenerating liver the amount of these peptides does not exceed 10 ng/mg protein. High pressure gel-filtration of appropriate extracts has revealed EGF-competing substances with m. w. about 20-30 kD in the liver carcinomas. The presented data confirm that registered EGF-like substances belong to TGF-alpha peptides.