Impaired Expression of Cytoplasmic Actins Leads to Chromosomal Instability of MDA-MB-231 Basal-Like Mammary Gland Cancer Cell Line.

We have shown previously that two cytoplasmic actin isoforms play different roles in neoplastic cell transformation. Namely, β-cytoplasmic actin acts as a tumor suppressor, whereas γ-cytoplasmic actin enhances malignant features of tumor cells. The distinct participation of each cytoplasmic actin in the cell cycle driving was also observed.

Myogenic potential of human alveolar mucosa derived cells.

Difficulties related to the obtainment of stem/progenitor cells from skeletal muscle tissue make the search for new sources of myogenic cells highly relevant. Alveolar mucosa might be considered as a perspective candidate due to availability and high proliferative capacity of its cells. Human alveolar mucosa cells (AMC) were obtained from gingival biopsy samples collected from 10 healthy donors and cultured up to 10 passages.

A Novel Three-Colour Fluorescence in Situ Hybridization Approach for the Detection of t(7;12)(q36;p13) in Acute Myeloid Leukaemia Reveals New Cryptic Three Way Translocation t(7;12;16).

The t(7;12)(q36;p13) translocation is a recurrent chromosome abnormality that involves the ETV6 gene on chromosome 12 and has been identified in 20-30% of infant patients with acute myeloid leukaemia (AML). The detection of t(7;12) rearrangements relies on the use of fluorescence in situ hybridization (FISH) because this translocation is hardly visible by chromosome banding methods. Furthermore, a fusion transcript HLXB9-ETV6 is found in approximately 50% of t(7;12) cases, making the reverse transcription PCR approach not an ideal screening method.

[Cytogenetic monitoring acute myeloid leucosis in children].

Preliminary results of cytogenetic monitoring acute myeloid leukosis (AML) in children are presented. Repeated chromosomal analyses were accomplished in 23 patients that presented with cell clones showing various karyotype abnormalities prior to the onset of therapy. All the patients were treated following identical protocols.

[Chromosomal translocation t(8,21) in acute myeloid leukemia of children: prognostic value of additional karyotype abnormalities].

Prognostic significance of additional karyotype abnormalities was studied in 73 children with t(8,21) acute myeloid leukemia (AML). Additional chromosomal aberrations were documented in 61 cases (83.6%).

[Complex karyotype abnormalities in pediatric acute myeloid leukemia].

A majority of the data on the prognostic significance of distinct chromosome changes and combinations of them in pediatric acute myeloid leukemia (AML) has been derived from adult studies, with not numerous published data in pediatric patients. One of points needed to be clarified is prognostic significance of complex karyotype (at least 3 unrelated abnormalities). We investigated characteristic features of complex karyotype in newly diagnosed pediatric AML de novo.

P53-dependent effects of RAS oncogene on chromosome stability and cell cycle checkpoints.

Mutations activating the function of ras proto-oncogenes are often observed in human tumors. Their oncogenic potential is mainly due to permanent stimulation of cellular proliferation and dramatic changes in morphogenic reactions of the cell. To learn more on the role of ras activation in cancerogenesis we studied its effects on chromosome stability and cell cycle checkpoints.

Increased karyotype precision using fluorescence in situ hybridization and spectral karyotyping in patients with myeloid malignancies.

We studied seven patients with various malignant hematologic disorders using fluorescence in situ hybridization (FISH) and one of these patients with spectral karyotyping (SKY). With appropriate probes, the t(8;21) and inv(16) were confirmed in two patients and the karyotypic precision was increased in five others using FISH and SKY. Two of three patients with 12p rearrangements had a deletion of one TEL allele.

[Karyotypic anomalies and chromosomal sites of increased fragility in colorectal cancer].

Karyotypic structural aberrations in tumor cells and chromosome constitutive fragile sites (cFSs) in peripheral blood lymphocytes were studied in ten patients with colorectal adenocarcinoma Most chromosome breakpoints (38 out of 40, i.e., 95.

[p53 with a mutation in codon 273 increases the probability of amplifying the dhfr gene in Rat-1 and LIM1215 cells].

The effect of the expression of the exogenous human mutant p53 (Arg-->His in codon 273) on the amplification rate of the gene dhfr in permissive Rat-1 and LIM1215 cells was studied. It was shown that injection of a retroviral construction with p53His273 resulted in the accumulation of methotrexate-resistant variants with an increased number of dhfr copies in populations of recipient cells. Luria-Delbruck fluctuation analysis revealed a four- to six-fold increase in the rate of appearance of new methotrexate-resistant cells.

Regularities of karyotypic evolution during stepwise amplification of genes determining drug resistance.

Analysis of chromosomal alterations during stepwise development of mdr1, dhfr, or CAD gene amplifications in a large number of independently selected Djungarian hamster DM-15 and murine P388 sublines revealed typical patterns of karyotypic evolution, specific for multiplication of each of these genes in each cell type. Some principal similarities of karyotypic evolution were noted in at least two different systems. They include: (i) appearance at the first selection step of a new chromosomal arm bearing the resident gene copy followed at the next selection steps by the formation in these specific chromosomal arms of amplified DNA tandem arrays; (ii) translocations of amplified DNA from its initial site to other, also non-random, chromosomal sites; and (iii) emergence in the cell variants with high degrees of gene amplification of multiple extra-chromosomal elements.

Enhanced expression of 1p32 and 1p22 fragile sites in lymphocytes in cutaneous malignant melanomas.

Frequency and distribution of 5-fluorodeoxyuridine (5-FdU) plus caffeine-induced fragile sites on chromosomes of peripheral blood lymphocytes (PBL) from 10 patients with cutaneous melanoma were studied in comparison with 10 PBL samples from normal donors of corresponding sex and age. The total number of breaks showed a significant difference among individuals in both groups, however, the average frequencies of 5-FdU plus caffeine-induced, as well as spontaneous damages in PBL from melanoma patients, were higher than those from healthy volunteers. The analysis of the breakpoint distribution showed a statistically significant increase in the expression of several fragile sites.

[Segments of Djungarian hamster chromosomes, specific for translocation of integration of amplified mdr1 genes, do not possess increased instability].

Earlier we have revealed in Djungarian hamster DM-15 cells three chromosomal segments (2p22, 5p1, 7q23-25) that are specific for transposition of amplified mdr1 genes from the site of location of resident gene copy (it was mapped to 4q21-23). In situ hybridization revealed in wild type cells no mdr1 homologous sequences in all these three segments. In this work we studied distribution of chromosomal breakages induced in DM-15 cells by aphidicolin, 5-fluorodeoxyuridine or N-phosphonacetyl-L-aspartate.

Non-random karyotypic changes in Djungarian hamster tumors induced by 3-methylcholanthrene.

The karyotypes of 30 tumors (sarcomas and adenocarcinomas) induced with methylcholanthrene in Djungarian hamsters (Phodopus sungorus campbelli) have been investigated. In 23 tumors structural changes of the short arm of X-chromosome (Xp+ or Xp = type) were revealed. Non-random rearrangements of 3p, 7q and 8q were also observed.

[Nonrandom karyotype changes in chemically induced tumors of the Djungarian hamster].

In the cells of tumors induced with methylcholanthrene in wild type and mutant (pink-eyed dilution) Djungarian hamsters non-random involvement in structural changes of certain chromosomes (Xp, 3p and 3q, 7q, 8q) was revealed. In addition, characteristic feature of the majority of tumors was varied number of double-minutes chromosomes (DMs). In some tumors, the markers with long homogeneously or differentially stained regions (HSRs and DSRs) were also present.

[Amplification of regions of the genome in the somatic cells of mammals resistant to colchicine. VII. Localization of the initial and amplified copies of gene mdr in one and the same segment of chromosome 4 of the Djungarian hamster].

By in situ hybridization technique, the mdr gene which is amplified during the development of multiple drug resistance was mapped in the 4q15--21 segment of normal Djungarian hamster chromosome 4. As was shown earlier, this chromosomal region is specific for the location of amplified mdr gene copies. These results, as well as some data obtained by other authors, suggest that recombinations of amplified DNAs occur preferentially in or near the sites bearing homologous sequences.

[Cloning and characteristics of DNA sequences amplified in Djungarian hamster cells with multidrug resistance].

A number of DNA clones containing the amplified DNA sequences were isolated from the genomic library of multidrug-resistant (MDR) Djungarian hamster cells using the DNAC0t 10-250 hybridization probe. Five independent nonoverlapping clones were obtained that covered more than 100 kb of the amplified genomic region. These clones were used as hybridization probes in blot-hybridization with DNA from 7 independently derived MDR Djungarian hamster cell lines selected for the resistance to colchicine or actinomycin D.

[Nomenclature of the metaphase chromosomes of the djungarian hamster].

The proposed nomenclature of G-banded chromosomes of Phodopus sungorus campbelli is based on requisites and principles of the International System for Human Cytogenetic Nomenclature (ISCN).

[Isolation of DNA probes for the detection of sequences amplified in colchicine-resistant cells].

Earlier we have found that the development of resistance to colchicine in mammalian cells in vitro is due to gene amplification leading to decreased plasma membrane permeability to the selective agent and some other unrelated drugs. By a stepwise self-renaturation procedure followed by chromatography on hydroxyapatite we isolated the fraction of middle-repeated sequences (DNAc0t = 10-250) enriched in amplified DNA from the DNA of colchicine-resistant Djungarian hamster cell line. Blotting-hybridization with [32P]DNAc0t = 10-250 performed in the presence of the excess of unlabelled DNA from wild type cells reveals amplified sequences in resistant cell lines.

[Sensitivity of grey and beige Djungarian hamsters to the blastomogenic action of 7,12-dimethylbenz(a)anthracene and 3-methylcholanthrene].

Sensitivity of normal gray and mutant beige (pink-eyed dilution mutation) Djungarian hamsters to the carcinogenic activity of 7,12-dimethylbenz (a) anthracene (DMBA) and 3-methylcholanthrene (MC) was studied. No differences between these two groups of animals which were given pills with DMBA were revealed. At the same time the beige females were found to be more sensitive to MC than males and hamsters of wild (gray) colour.

[Possible role of the T antigen in inducing chromosome aberrations in SV40 virus-transformed cells].

A possible role of the simian virus 40 T antigen in chromosome damages in transformed cells was examined. Two lines of Golden hamster embryonal fibroblasts, transformed by SV40 tsA30 and ts239 mutants (He30 and He239, respectively), were incubated at nonpermissive (40.5-41 degrees C) or permissive (33 degrees C) temperatures.

A new cell system for the study of mouse mammary tumour virus.

A stable cell line derived from mammary gland cancer of Djungarian hamster is proposed for the study of oncogenic properties of mouse mammary tumour virus (MMTV). The conditions of infection and expression of the viral genome in this cell line are described in addition to the chromosomal composition or the original and infected cells. The MMTV-infected cells showed increased colony formation in semi-solid media.