[Multipotent mesenchymal stem cells of desquamated endometrium: isolation, characterization and use as feeder layer for maintenance of human embryonic stem cell lines].

In this study, we characterize new multipotent human mesenchymal stem cell (MSC) lines derived from desquamated (shedding) endometrium in menstrual blood. The isolated endometrial MSC (eMSC) is an adhesive to plastic heterogeneous population composed mainly of endometrial glandular and stromal cells. The established cell lines meet the criteria of the International Society for Cellular Therapy for defining multipotent human MSC of any origin. The eMSCs have positive expression of CD73, CD90, CD105, CD13, CD29, CD44 markers and the absence of expression of the hematopoietic cell surface antigens CD19, CD34, CD45, CD117, CD130 and HLA-DR (class II). Multipotency of the established eMSC is confirmed by their ability to differentiate into other mesodermal cell types such as osteocytes and adipocytes. Besides, the isolated eMSC lines partially (over 50%) express the pluripotency marker SSEA-4, but do not express Oct-4. Immunofluorescent analysis of the derived cells revealed the expression of the neural precursor markers nestin and beta-III-tubulin. This suggests a neural predisposition of the established eMSC. These cells are characterized by high rate of cell proliferation (doubling time 22-23 h) and high cloning efficiency (about 60%). In vitro the eMSCs undergo more than 45 population doublings revealing normal karyotype without karyotipic abnormalilies. We demonstrate, that the mititotically inactivated eMSCs are perfect feeder cells for human embryonic stem cell lines (hESC) C612 and C910. The eMSC being a feeder culture maintain the pluripotent status of the hESC, which is revealed by the expression of Oct-4, alkaline phosphatase and SSEA-4. When co-culturing, hESC retain their morphology, proliferative rate for more than 40 passages and capability for spontaneous differentiation into embryoid bodies comprising the three embryonic germ layers. Thus, an easy and non-invasive extraction of the eMSC in menstrual blood, their multipotency and high proliferative activity in vitro without karyotypic abnormalities demonstrate the potential of use of these stem cells in regenerative medicine. Using the derived eMSCs as the feeder culture eliminates the risks associated with animal cells while transferring hESC to clinical setting.

[The effect of synthetic polycation polyallylamine on adhesion and viability of CHL V-79 RJK Chinese hamster fibroblasts with different heat resistance].

The effects of synthetic polycation polyallylamine (PAA) on adhesion of CHL V-79 RJK fibroblasts and CHL V-79 RJK40 cells resistant to 40 degrees C, and attachment to these cells to polycation immobilized on polystyrene surface were studied. We have also investigated the cytotoxicity of PAA. It was shown that cell adherence to polystyrene plastic coated with PAA was enhanced or decreased in dependence of the PAA concentration used for surface coating and did not depend on heat resistance of investigated cell lines. The effect of PAA on cell adhesion to uncoated polystyrene surface after cell exposure with PAA depended not only on the polycation concentration, but also on the extent of heat resistance of investigated cell lines. Pretreatment of CHL V-79 RJK cells with PAA at the nontoxic concentrations led to inhibition of cell adhesion, and no change in adhesive properties of thermoresistant cells was found under the same conditions. PAA was toxic for CHL V-79 RJK and CHL V-79 RJK40 cells only at concentrations of 100 microg/ml (MTT assay). PAA-induced acute toxicity was accompanied by necrotic-like cell damage. Possible mechanisms of the PAA effect on the behaviour of cells with different structural and metabolic characteristics that are due to the temperature of cell cultivation are discussed.

[Growth modulating and cytotoxic effects of the peptide from hemolymph of blow fly Calliphora vicina (Diptera, Calliphoridae) in vitro].

Biological activity of alloferon (AF), peptide, consisting of 13 a. a. isolated from hemolymph of experimentally infected blow fly Calliphora vicina was studied. AF in concentrations form 1 x 10(-5) to 250 microg/ml was added into the culture medium of the target cell lines K562, J-96, P388DI, Hep22a and 3T3B-SV40. First two days the peptide in concentrations 1 x 10(-5) and 1 x 10(-3) microg/ml in most cases stimulated the cell proliferative activity and suppressed the cell growth when applied in concentrations 10 and 100 microg/ml. Trend in growth modulating effect was dependent on duration of AF treatment. The peptide did not expressed cytotoxic effect with the exception of destruction of P388D1 cells that was registered after 96 h incubation in the medium initially contained 100 microg/ml AF. Simultaneously, cytotoxic and growth modulating effects of doxorubicin and cytosinarabinoside, as well as hybrid molecules, AF--cytosinarabinoside (cytal) and AF--doxorubicin (doxal) have been studied. Doxorubicin and cytosinarabinoside expressed greater growth inhibition effect compared to the hybrid molecules and AF itself. The results obtained with mass cell cultures were supported by experiments where P388D1 cells clonogenic capacity was tested. Besides, it has been demonstrated that AF rapidly penetrates into cytoplasm of J-96 cells and concentrates mainly into and around the cell nuclei.

[Chromosomal rearrangements and their effects in spontaneous immortalization and transformation of rat embryo cells in vitro].

G-banding analysis of LRec-1 and LRec-3, spontaneously immortalized cell lines from rat embryo fibroblast, revealed diploid karyotypes with specific clonal structural rearrangements of chromosomes 7 and 19 - del(7)(q11.2q22.1), t(7;19)(q11.1;q12) in malignant stage. Both clonal abnormalities of chromosomes 7 and 19 were also revealed in LRec-1k clone and LRec-1 sf cell line. Previous study of LRec-1 and LRec-3 cells showed the presence of karyotypes with pseudodiploid modal chromosome number, partial trisomy of chromosome 7 and same clonal structural rearrangements of chromosomes 7 and 19 in immortalized stage. In malignant stage, the trisomy 6 and new clonal structural rearrangements of chromosomes 1, 2, 11, 15, 18, 19 and of chromosomes 10, 20 were also found in LRec-1 sf and LRec-1 cells, accordingly. There were no new clonal structural chromosome rearrangements in LRec-1 k and LRec-3 cells. We compared locies of chromosomes involved in rearrangements with mapped genes on these chromosomes according to RATMAP. Supposedly these genes are involved in spontaneous immortalization of rat embryo fibroblast and malignant transformation of LRec-1 and LRec-3 cells and rearrangements of chromosomes 1, 2, 11, 15 and 18 facilitate expression of growth factors of LRec-1 sf cells.

[Microfluorimetric analysis of dynamics of genomic changes of Chinese hamster fibroblasts CHL V-79 RJK with multidrug resistance].

Results of karyological analysis of cells CHL V-79 RJK selected for resistance to ethidium bromide (EB) causing multidrug resistance (MDR) (line Vebr-5) were compared with the data of microfluorimetric determination of DNA content in individual chromosomes of the karyotype. The analysis was performed at the 11th and 88th passages. Karyotyping of Vebr-5 has shown the presence of an additional genetic material (ADM) in the form of homogenously or differentially stained regions (HSRs and DSRs, respectively) in two chromosomes (Z1 and Z6, loci 1 p29-31 and 1q26, respectively). HSRs in Z6, in the region of localization of the wild type of gene mdr, had unstable length and structure characteristic of morphological markers of amplification of genes of the family mdr. During long cultivation of Vebr-5 in the presence of EB (88 passages), the instability of HSRs in Z6 increased. Results of microfluorimetric analysis of Vebr-5 at the 11th passage have shown an increase in the DNA content not only in chromosomes Z1 and Z6 marked by HSRs, but also in three chromosomes (Z5, Z12 and Z13) that have no visual morphological changes. The corresponding analysis at the 88th passage has also revealed non-random changes in the DNA content in four more chromosomes: an increase in Z14, while a decrease in chromosomes 8, Z7, and Z9. A decrease of the DNA content in chromosomes is considered to be a result of a partial loss of genetic material, while its increase is a result of its translocation and (or) amplification. Coefficient of variation of the DNA content changes for large chromosomes amounted to about 9%. while for small chromosomes it is about 26%, which indicates that small chromosomes have greater potential for instability than the large ones. The data obtained not only confirm, but also enlarge the concept of directions and character of destabilization of the cell genetic apparatus in the process of neoplastic transformation due to the MDR acquisition by cells.

[Clonal analysis of the heterogeneity of neoplastic hepatocytes]. / Klonal'nyi analiz geterogennosti opukholevykh gepatotsitov.

The heterogeneity of hepatoma MH-22a cell line was studied by clonal analysis on the basis of the following factors: splenocyte-induced apoptosis of tumor hepatocytes, tumor hepatocyte-induced apoptosis of splenocytes and profile of B1-associated DNA fragments. Induction of apoptosis of tumor hepatocytes by splenocytes and of splenocytes--by tumor hepatocytes was carried out in the main population of hepatocytes and in five clonal lines of hepatoma MH-22a. Genetic heterogeneity was studied using the same material and PCR primed for murine B1-elements. It was shown that apoptosis of hepatocytes of the main population and two clonal lines of hepatoma MH-22a was induced by splenocytes. The ability to induce apoptosis of splenocytes was observed in the same clonal lines and population of tumor hepatocytes. The latter involved enhanced genetic heterogeneity which was identified by B1-PCR analysis. Thus, a correlation was established in tumor hepatocytes between apoptosis-related characteristics and frequency of genome rearrangements.

[Cytotoxic and mitogenic effect of antimicrobial peptides from neutrophils on cultured cells]. / Tsitotoksicheskoe i mitogennoe vliianie antimikrobnykh peptidov neitrofilov na kul'tiviruemye kletki.

Cytotoxic and mitogenic activities of human and rabbit defensines (HNP and NP-2, resp.) and pig antimicrobial peptides from leukocytes (PR-39, prophenin PF-2 and protegrin PG-2) were studied. The above peptides were added to serum-free cell culture medium of the target cell lines K562, L929 and Hep22a. Cytotoxicity was estimated within 1, 3, 6, 24 and 48 h of cell incubation with the tested peptides in concentrations 1, 10, 25 or 100 micrograms/ml. All the examined peptides exhibited a distinct time- and concentration-dependent cytotoxicity. Moreover, by contrast to pig peptides, defensines could induce proliferation in cell subpopulations from cell lines L929 amd Hep22a, or L929 (defensines HNP and NP-2, resp.), keeping resistance to their cytotoxic action.

[Pleiotropic changes in karyotype structure of Chinese hamster fibroblast cell lint CHL V-79 RJK in relation to their acquisition of resistance to etoposide, an inducer of apoptosis]. / Pleiotropnye izmeneniia struktury kariotipa fibroblastov kitaiskogo khomiachka linii CHL V-79 RJK v sviazi s priobreteniem imi ustoichivosti k étopozidu-induktory apoptoza.

Chinese hamster fibroblasts CHL V-79 RJK were subjected to multistep selection in the presence of etoposide, known as an inhibitor of topoisomerase II and inductor of apoptosis. The karyotype of cells stably resistant to etoposide was analysed at progressive stages of selection using G-type staining of metaphase chromosomes. Multiple changes in the karyotype of resistant cells were observed at an early stage of selection (0.2 mg/ml of etoposide) and included: random chromosome breaks leading to formation of new chromosome markers, high frequency of aneuploid and polyploid cells, morphological instability and extracopy of q-shoulder of chromosome 1. On advanced stages of selection we observed an increased frequency of specific minute chromosome and the appearance of chromosomes with homogeneously or differentially stained regions (HSR and DSR). These data suggest that different mechanisms may be involved in developing cellular resistance to etoposide at progressive stages of selection.

[The release and absorption of small ribonucleoprotein complexes (alpha RNPs) in cultures of transformed rat fibroblasts and human epidermoid carcinoma]. / Eksport i pogloshchenie malykh ribonukleoproteinovykh kompleksov (al'fa RNP) v kul'turakh transformirovannykh krysinykh fibroblastov i épidermoidnoi kartsinomy cheloveka.

The release of alpha RNPs and their absorbtion by the cells from culture medium were studied. The rat fibroblasts of parental serum-dependent cell line LRec-1, and of selected serum-free cell line LRec-1sf rapidly released and absorbed alpha RNPs. In the latter case, both auto- and heterologous alpha RNPs were seen to penetrate, whereas only autologous alpha RNPs entered LRec-1 cells. Besides, the ability to rapid export and absorbtion of autocrine alpha RNPs was demonstrated for human epidermoid carcinoma cell line A431. Both LRec-1 and LRec-1sf cells expressed mRNAs with homology to ID-like nucleotide sequences, the level of mRNA expression decreasing markedly when serum-dependent LRec-1 cells were grown in serum-free medium.

[The growth-stimulating and immunomodulating activity of culture media conditioned by transformed fibroblasts from serum-free lines]. / Roststimuliruiushchaia i immunomoduliruiushchaia aktivnost' kul'tural'nykh sred, konditsionirovannykh transformirovannymi fibroblastami bessyvorotochnykh linii.

Five cell lines of transformed rodent fibroblasts capable of unlimited growth without exogenous proteins were studied. It has been demonstrated that the media conditioned by these cells (CMs), the protein preparations obtained from CMs, or the feeder cell cultures of the serum-free cell lines are mitogenic to mouse hybridoma cells as well as to primary cell cultures of the rat bone marrow. The addition of CMs proteins into mixtures of mouse splenocytes and transformed target cells resulted in stimulation or suppression of the splenocyte cytotoxicity when YAC-1 [correction of JAC-1] or K562 cell targets were used. A 18-20 h splenocyte preincubation with proteins, released by transformed rat fibroblasts of the serum-free cell line LRec-1sf, resulted in a 1.5-4-fold increase in K562 cell lysis by murine natural killer cells. By contrast, the target cell preincubation with the same proteins resulted in a 1.5-2-fold decrease in K562 cell sensitivity to cytotoxic effect of natural killer cells. Taken together our data show that the transformed rodent fibroblasts, growing without exogenous proteins, produce and release into the culture medium some growth stimulating, immunomodulating and immunoprotective factors.

[The karyotypic variability of Chinese hamster CHLV-79 RJK cells characterized by multiple drug resistance resulting from the amplification of the mdr gene family]. / Izmenchivost' kariotipa kletok kitaiskogo khomiachka CHLV-79 RJK, kharakterizuiushchikhsia mnozhestvennoi lekarstvennoi ustoichivost'iu, obuslovlennaia amplifikatsiei genov semeistva mdr.

Variability in karyotype structure of Chinese hamster lung V-79 RJK cells and of their six cell sublines, selected for increasing concentrations of ethidium bromide (EB), was investigated in addition to the number of mdr gene copies in cells, both EB sensitive and resistant. It is shown that EB resistant cells exhibit cross-resistance to different drugs resulting from mdr genes amplification. Southern DNA blot hybridization has shown that in Vebr-2 cells (the 1st step of selection) the number of mdr gene copies increased by 10 times, whereas in Vebr-30 cells (the 6th step of selection) the number of mdr gene copies remained the same as in Vebr-2 cells. The level of mdr genes expression in Vebr-30 cells being higher than in Vebr-2 cells. In Vebr-2 cells, homogeneously and differentially stained regions (HSRs) were detected in loci 1p31 and 1q26 of chromosome 1 material (markers Z1 and Z6, respectively). On the following selection steps (prolonged cultivation or increased drug concentration) additional HSRs appeared in chromosome 2 (locus 2qter), in derivatives of chromosome 5 (marker Z7, locus Z7pter) and chromosome X (marker Z2, locus Z2qter). In the course of prolonged cultivation, chromosome 2 and derivatives of chromosomes 1, 2, 5 and X, in which HSRs were found, participated in the formation of new markers resulting from deletions, inversions, insertions and translocations of the chromosomal material. It is supposed that mdr genes amplification in V-79 RJK cells resistant to EB may be regarded as a factor inducing subsequent genome destabilization and eventual progressive changes in the karyotype structure.

[The use of B1-PCR method for studying the genomic polymorphism involved in malignant growth]. / Ispol'zovanie metoda v1-ptsr dlia izucheniia genomnogo polimorfizma pri zlokachestvennom roste.

The BI-PCT method showed the profile of BI-associated fragments of LNA in the cell line of the mouse hepatoma MH-22a to differ from that of the liver cells of C3HA mice, hepatoma cells incorporating the DNA fragments with 450 bp and those with 600bp disappearing. Application of the same method failed to reveal any differences in the profiles of BI-associated DNA fragments in the differentiated and non-differentiated cells of the embryonal carcinoma F9 induced by retinoic acid and cAMP dibutyryl treatment. It is suggested that the spectra of BI-associated DNA fragments might correlate with genetic stability in tumor cells.

[The amplification and overexpression of mdr-family genes in ethidium bromide-resistant Chinese hamster CHO-K1 cells and in the hybrids of sensitive and resistant cells]. / Amplifikatsiia i sverkhékspressiia genov semeistva mdr v ustoichivykh k bromistomu étidiiu kletkakh kitaiskogo khomiachka CHO-K1 i v gibridakh chuvstvitel'nykh i ustoichivykh kletok.

Stable mutant cells Cebr-1 and Cebr-2, resistant to ethidium bromide (EB) in concentration of 2 micrograms/ml, have been isolated by a multistep selection in Chinese hamster ovary cells. It was shown that Cebr-1 and Cebr-2 cells acquired a cross-resistance to unrelated drugs. Stable changes in the structure of chromosomes 1, 2, 5 and 8 were revealed by karyological analysis. Overexpression and amplification of mdr genes were detected in Cebr-2 cells using Northern RNA and Southern DNA blot hybridization. Two independent hybrids Hybr-1 and Hybr-2 were obtained by fusion of Cebr-2 cells with Chinese hamster lung V-79 RJK cells, sensitive to EB. Hybr-2 cells were characterized by the same level of EB-resistance as Cebr-2 cells. Hybr-1 cells have a lower level of EB-resistance than Cebr-2 cells. Hybr-2 cells have demonstrated amplification and overexpression of mdr gene, the same as in Cebr-2 cells, whereas in Hybr-1 cells no mdr gene amplification was observed, but the level of mdr gene expression was higher than in sensitive cells. The data suggest that resistance of Chinese hamster cells to EB is mediated by amplification and overexpression of mdr genes.

[A cytogenetic analysis of the cells of spontaneously transformed LREC rat cell lines. I. Chromosomal rearrangements detected in the early stages of rat embryonic cell transformation in vitro]. / Tsitogeneticheskii analiz kletok spontanno transformirovannykh kletochnykh linii krys LREC. I. Perestroiki khromosom, vyiavliaemye na rannikh stadiiakh transformatsii émbrional'nykh kletok krys in vitro.

Seven spontaneously transformed cell lines LREC of rat embryo fibroblasts were obtained by an originally elaborated cloning technique (method 2T7). Six lines (1-6) were obtained from Rattus norvegicus cells, and one line (LREC-7) from Wistar rats. Method 2T7 was based on a serial propagation of rat embryo cells, brought to a "crisis" stage under conditions of a higher cell density and followed by the appearance of actively proliferating cell clones. These lines were analysed cytogenetically at the earliest stages using the Giemsa G-banding technique. In the karyotypes of six LREC (1-6) lines two abnormal chromosomes 7 were revealed: one marker chromosome M1-t(7; 19) results from translocation between chromosomes 7 and 19, the other marker chromosome M2--del(7) is a result of deletion of the second homolog of chromosome 7 in the q11.2 q22.1 loci; besides an extra normal homolog of chromosome 7 was revealed. There are only two marker chromosomes M2 in the LREC-7 line karyotype. Cells of LREC (1-3) lines could be transformed from the immortalized stage to the malignant one by the 30-45th passages. The cells of LREC (4, 7) lines became malignant at the 10-8th passages, resp. The rearrangements of chromosome 7 are supposed to be specific for LREC lines obtained by our method. A hypothesis is put forward that the translocation of chromosome 7 may play an important role for the immortalization of the rat embryo cells. The deletion of chromosome 7 may be associated with a malignant transformation of cells, as it is possible that the deleted loci have a recessive oncogene. Method 2T7 allows to obtain constantly spontaneously transformed cell lines of rat embryo cells with the least abnormal karyotype.

[The cultivation features, growth characteristics and oncogenicity of "serum-free" populations of transformed fibroblasts]. / Osobennosti kul'tivirovaniia, kharakteristiki rosta i onkogennost' "bessyvorotochnykh" populiatsii transformirovannykh fibroblastov.

The authors report about five previously selected cell lines of transformed mouse and rat fibroblasts, capable of growing in the medium lacking exogenous proteins. In contrast to cells of the parental lines, the cells under investigation have the ability to semi-suspension growth pattern and demonstrate an increasing sensitivity to damaging action of trypsin. The lowering of the autological conditioned medium (CM) concentration below 10-15%, as well as the reducing of the initial population density to 0.2 x 10(4)-0.4 x 10(5) cells per 1 cm2, resulted in inhibition of the serum-free cell proliferation. The feeder cultures of the serum-free cells immobilized by X-ray are able to stimulate proliferation of the intact autological cells in medium with semi-liquid agar in the presence of serum. CMs of the serum-free cell cultures stimulated the DNA synthesis in stationary cultures of NIH 3T3 cells in the absence of serum. The loss of dependence on serum was accompanied by a considerable broadening of the metionine-containing protein spectrum in the culture medium of the transformed rat embryo fibroblasts. In addition, it was demonstrated that selection for independence on exogenous proteins was accompanied by the loss of oncogenicity in both sensitive and resistant to cytotoxic effect of ethidium bromide serum-free cell lines, derived from L929 cell line. On the contrary, the serum-free variants from spontaneously transformed rat embryo fibroblasts as well as from C3H 10T1/2 cell line exhibit an enhanced oncogenicity as compared with the parental cells.(ABSTRACT TRUNCATED AT 250 WORDS)

[The amplification and overexpression of the mdr genes in Chinese hamster CHLV-79 RJK cells resistant to ethidium bromide correlate with the presence of karyotypic markers of the amplification]. / Amplifikatsiia i sverkhékspressiia genov mdr v kletkakh kitaiskogo khomiachka CHLV-79 RJK, ustoichivykh k bromistomu étidiiu, sochetaetsia s nalichiem kariotipicheskikh markerov amplifikatsii.

Evidence is provided that selection of the Chinese hamster cells CHLV-79 RJK with ethidium bromide results in amplification and overexpression of mdr family genes, one of which is encoding a transmembrane P-glycoprotein reducing the intracellular drug concentration. It is likely that the amplified copies are located at or near the sites of resident mdr gene localization to look as an abnormal chromosomal banding pattern in chromosome 1q26. In the following selection steps to higher drug concentration, the cells are keeping the degree of amplification, but mdr gene expression increases by many times. The data suggest that the resistance of the Chinese hamster cells CHLV-79 RJK to higher concentrations of ethidium bromide may be achieved via a variety of mechanisms, including as well mdr gene amplification as transcriptional regulation of these genes.

[New lines of spontaneously transformed cells obtained from "precrisis" cultures of embryonic rat cells]. / Novye linii spontanno transformirovannykh kletok, poluchennye iz "predkrizisnykh" kul'tur émbrional'nykh kletok krys.

A new approach to selection of lines of spontaneously transformed cells from the rat embryo "precrisis" cultures is described and their phenotypes at the initial and advanced stages during a long-term cultivation are characterized. The new selective system, referred to as 2T7, differs from the well known 3T3, 2T6 and 3T12 systems (Todaro, Green, 1963; Aaronson, Todaro, 1968). It is based on the maintenance of cultures under maximum cell densities. Such an approach facilitated and accelerated the start of the "crisis" stage (up to 3-8 passages) with the following gradual death of almost the whole normal senescent cell population, the colony formation resulting from the proliferation of single clonogenic cells. The frequency of clonogenic cells was about 6 x 10(-6). Six lines of spontaneously transformed cells from embryos of noninbred white rats (LRec-1--LRec-6) and one line from the Wistar embryos (LRec-7) were established. All the lines are characterized as diploid or near-tetraploid, with 1-4 different marker chromosomes formed from chromosome 7, as was reported elsewhere (Artsybasheva et al., 1988). The values of saturation densities and the time of population doubling for all the 7 lines differed from those for the rat embryo primary cultures cells. LRec-1--LRec-6 cells were unable to form the colonies in soft agar, while LRec-7 cells were able to grow in agar. The lines LRec became oncogenic for 1-2 day old rats after different periods of cultivation in vitro--from 3 to 7 months. The line LRec-7 Wistar appeared to be highly oncogenic from the very beginning after its selection. The histological analysis revealed that the LRec-1 tumors could be classified as polymorphocellular sarcoma. Up to 20 passages the LRec-1 line had numerous clonogenic cells (50-60%) in sparse cultures independently on the serum content in the media. By a 3-step selection of LRec-1 cells, on cultivation in media with lower serum contents (1-0.1-0%), a semisuspension of LRec-1sf subline (serum free) was established. This line was highly oncogenic for 1-2 day old rats, was easily cryopreserved and proliferated in the serum-free media for unlimited time, forming small colonies in agar. Thus, the new approach allows to establish with high effectiveness spontaneous lines of rat embryo cells with differently transformed phenotypes, i.e. preneoplastic and oncogenic ones.(ABSTRACT TRUNCATED AT 400 WORDS)

[Chromosomal polymorphism of mammalian cells resistant to drugs in multiple passages. I. Karyotype analysis of Chinese hamster cells resistant to ethidium bromide in the early passages of the first steps of selection]. / Khromosomnyi polimorfizm kletok mlekopitaiushchikh s mnozhestvennoi lekarstvennoi ustoichivost'iu. I. Analiz kariotipa kletok kitaiskogo khomiachka, ustoichivykh k bromistomu étidiiu, na rannikh passazhakh pervykh stupenei selektsii.

G-banded metaphase chromosomes of Chinese hamster V-79 RJK cells resistant to ethidium bromide (2.5 and 10 mcg/ml) have been analysed. The cells of the first selection step (clone IVerb-2, the 9th passage) revealed definite karyotypical instabilities. Amplifications or, in rare cases, deletions were found in chromosomes Z1 and Z6 which appear to have derived from chromosome 1. The amplified region in chromosome Z6 varied considerably in morphology. The chromosome instability, detected in Z1 and Z6, was reproducible in cells throughout the eight independent clones isolated from clone IVebr-2 under non-selective conditions. The data obtained allow to suggest a genetically conditioned mechanism of the above chromosome instability. In the population of resistant cells on the second step of selection (clone I Vebr-5, the 9th passage) the frequency of the cells with amplification increased up to 100%. The length of amplifications increased in the majority of cells. In the cells of the third step of selection (clone IVerb-10, the 12th passage) with near-tetraploid chromosome composition, besides amplifications some specific rearrangements of chromosomes 2 and 7 (markers Z16, Z17) were revealed. The above rearrangements are indicative of the karyotypical destabilization in the drug resistant cells, and may be evaluated as secondary phenomena casually connected with amplifications found at the earlier steps of selection.