Chromosome morphologies revealed by Giemsa-banded karyotypes and chromosome numbers were compared between parental tumor-, lymph node- and lung metastasis-derived rat 13762NF mammary adenocarcinoma cell lines and clones having different spontaneous metastatic potentials. Although chromosome numbers in the cell lines and clones generally correlated with DNA content by flow cytometry, ploidy did not correlate with spontaneous metastatic potentials. Chromosome number and DNA content drifted during prolonged in vitro growth in each of the cell lines and clones. Common chromosome rearrangements were found, confirming a common origin for all the cell lines and clones, and the frequency and appearance of the individual marker chromosomes fluctuated during in vitro growth. Karyotypic analyses revealed that the markers coinciding with phenotypic drift in spontaneous metastatic potential and other biological properties of parental tumor-derived clones MTC and MTF7 and lung metastasis-derived clone MTLn3 involved chromosomes 3, 4, 5, 6, and 8. Clone MTC exhibited a shift in several markers and an increase in metastatic potential at passage T20, while clone MTF7 displayed a lesser spontaneous metastatic potential at high passage (T34) concomitant with an increase in the frequency of certain marker chromosomes. Lung metastasis-derived clone MTLn3 also exhibited a shift in some marker chromosomes, colonization preference and metastatic potential to lung and lymph nodes at high tissue culture passages. The changes in marker chromosomes during in vitro passage of clones MTC and MTLn3 suggested the presence of at least two cell subpopulations which could be responsible for the observed shift in spontaneous metastatic properties. Karyotypic features of the 13762NF cell lines and clones indicate that subtle cytogenetic changes, in contrast to gross chromosomal abnormalities, may be more important in determining metastatic phenotype.

Animals↗

PubMedDate not supplied

Caspase-dependent apoptosis induced by telomere cleavage and TRF2 loss.

Chromosomal abnormalities involving telomeric associations (TAs) often precede replicative senescence and abnormal chromosome configurations. We report here that telomere cleavage following exposure to proapoptotic agents is an early event in apoptosis. Exposure of human and murine cancer cells to a variety of pro-apoptotic stimuli (staurosporine, thapsigargin, anti-Fas antibody, and cancer chemotherapeutic agents) resulted in telomere cleavage and aggregation, and finally their extrusion from the nuclei. Telomere loss was associated with arrest of cells in G2/M phase and preceded DNA fragmentation. Telomere erosion and subsequent large-scale chromatin cleavage were inhibited by overexpression of the anti-apoptotic protein, bcl-2, and two peptide caspase inhibitors (BACMK and zVADfmk), indicating that both events are regulated by caspase activation. The results demonstrate that telomere cleavage is an early chromatin alteration detected in various cancer cell lines leading to drug-induced apoptosis, and suggest that this event contributes to mitotic catastrophe and induction of cell death. Results also suggest that the decrease of telomeric-repeat binding factor 2 (TRF2) may be the earliest event in the ara-C-induced telomere shortening, induction of endoreduplication and chromosomal fragmentation leading to cell death.

Animals↗

PubMedDate not supplied

Argentophilic structures of spermatogenesis in the yellow fever mosquito.

Application of the silver-staining technique to air-dried chromosome preparations of the yellow fever mosquito, Aedes aegypti, revealed the following: 1) intensely stained pericentromeric regions in all chromosomes including the Y chromosome in spermatogonia, and during the primary and secondary spermatocytes; 2) the presence of prepachytene that were not reported earlier; 3) a nucleolus organizing region that persisted up to the late pachytene stage; and 4) rod or ring-like centrioles in pachytene and diplotene stages. In addition, varying numbers (1-4) of silver-stained, ring-like structures were observed during spermiogenesis. The exact nature and function of these ring-like structures is not understood.

Aedes↗

PubMedDate not supplied

Demyelination induced in mice by avirulent Semliki Forest virus. I. Virology and effects on optic nerve.

Swiss A2G mice were infected intraperitoneally with an avirulent strain of Semliki Forest virus. The virus titres in the optic nerves, retina and brain were estimated on post-inoculation days 3 to 8. High titres of virus were obtained in the optic nerve, retina and brain. The optic nerves, retina and brain were studied by light microscopy up to post-inoculation day 67. Electron microscope studies wee carried out on the optic nerve on post-inoculation days 11 and 14. Inflammatory, microcystic changes and demyelination seen in the optic nerve were similar to those found in he central nervous system.

Animals↗

PubMedDate not supplied

Effect of myocrisin (sodium auro-thio-malate) on the morphogenesis of avirulent Semliki Forest virus in mouse brain: an electron microscopical study.

Adult mice, infected intracerebrally or intraperitoneally with avirulent Semliki Forest virus, do not show mature virus or advanced stages of viral replication in the brain. If myocrisin is given intraperitoneally 3 h before the virus there is enhancement of all stages of viral replication and budding of virus and mature virions are seen. Compared with controls many intracytoplasmic smooth membrane vesicles were seen in the parenchymal cells of the brain treated with myocrisin or with myocrisin and virus. Myocrisin was visible in the brain and has a membrane proliferating effect which may enhance viral synthesis in the early stages of replication, as well as help in the assembly and budding of mature virus. Increased numbers of infiltrating cells were observed in myocrisin treated mice infected with SFV. The formation of mature virus, and its virulence, appears to be related to the degree of membrane proliferation of the brain cells. The inflammation associated with the increased number of infiltrating cells is secondary to this, the whole process promoting the death of the animals rather than survival.

Animals↗

PubMedDate not supplied

A preliminary study of the activation of endogenous pancreatic exocrine enzymes during automated porcine islet isolation.

The activation of endogenous pancreatic enzymes during automated pancreas digestion may be detrimental to islet isolation. In this report we assessed the activation of trypsin, chymotrypsin, elastase, carboxypeptidases A and B, phospholipase A2, and lipase using a porcine model. Four islet isolations were examined. Duplicate aliquots were taken from the automated circuit at 5-min time intervals up to the completion of pancreas digestion (approx 60 min). One aliquot was activated in vitro with exogenous trypsin in order to convert the enzymes into their active non-"proform," with the exception of trypsinogen, which was activated with exogenous enterokinase. This was done to assess the percentage activation of each individual enzyme (total potentially activatable enzyme release). The extent of activation between isolations was extremely variable. During the closed (recirculating) circuit phase of pancreas digestion there were both gradual and rapid increases in the levels of enzymes released. Peak activity of enzyme activation varied from 13 to 30 min; similarly, total potentially activatable peaks occurred between 13 and 38 min. Lipase and carboxypeptidase B showed greater than 70% activation, chymotrypsin, carboxypeptidase A, and phospholipase A2 between 50% and 70% activation, and trypsin and elastase less than 20%. There were up to 30-fold differences between the four islet preparations. In summary, it is unlikely that poor islet yields are soley explained by variations between collagenases; the variable activation of endogenous pancreatic exocrine enzymes is also likely to be influential to porcine islet yields.

Animals↗

PubMedDate not supplied

Distinctive karyotypes and growth patterns in nude mice reveal cross-contamination in an established human cancer cell line.

A human cancer cell line was found to be heterogeneous for expression of the epidermal growth factor receptor (EGFR). Clones and variants of this cell line were separated on the basis of EGFR expression level, and those expressing high EGFR had different growth characteristics, in vitro and in vivo, than variants expressing low levels of EGFR. Karyotype analysis revealed that the heterogeneity was the result of mixing of two lines, the 2774 ovarian cancer cell line, and the SW620 colon cancer cell line. Our results reinforce the necessity for accurate identification of cell lines. Also, that measurement of gene expression on a single cell level, for example by flow cytometric analysis, can be more informative than measurements of cell lysates, since the initial indication of heterogeneity would not have been detected by northern or western blotting. The different cell types retained characteristic growth patterns when injected i.p. in nude mice, i.e. peritoneal carcinomatosis and ascites formation by the 2774 ovarian cancer cells, and liver metastasis and growth of discrete abdominal tumors by the SW620 colon cancer.

Animals↗

PubMedDate not supplied

Dolastatin-10 induces polyploidy, telomeric associations and apoptosis in a murine melanoma cell line.

Our purpose was to study the effects of dolastatin-10 (Dol-10) on chromosome morphology, telomeric associations, induction of polyploidy and cell death in a metastatic murine melanoma cell line, K1735 clone X-21. Murine melanoma cells were treated with various concentrations (10 ng/ml, 100 ng/ml and 1000 ng/ml) of Dol-10 for 4, 24 and 72 h continuously and harvested immediately without recovery. In another set of experiments, cells were treated for 4 h with the same concentrations, washed with prewarmed medium and then allowed to recover in drug-free medium for 24 h and subsequently harvested. Our preliminary results indicated: i) a drug-mediated increase in the frequency of metaphases, with telomeric associations resulting in multicentric and ring configurations; ii) induction of clumping in metaphase chromosomes; iii) induction of polyploidy as a result of endoreduplication; iv) formation of micronucleated cells; and v) induction of cell death. These observations indicated that Dol-10 could be a potent antineoplastic drug against malignant melanoma. In addition to its reported interaction with cell microtubules, the mechanism of action of Dol-10 may be mediated through the loss of telomeric repeats and induction of chromosome aberrations.

Animals↗

PubMedDate not supplied

Cell-killing by paclitaxel in a metastatic murine melanoma cell line is mediated by extensive telomere erosion with no decrease in telomerase activity.

The purpose of this study was to investigate and compare the effects of paclitaxel and its water-soluble conjugates (sodium-pentetic acid-paclitaxel; polyethylene glycol-paclitaxel, and poly[L-glutamic acid]-paclitaxel) on chromosome morphology and induction of apoptosis in a metastatic murine melanoma cell line (K1735 clone X-21). For this, murine melanoma cells were treated continuously for 72 h with three concentrations (1.2 microM, 2.4 microM, and 4.8 microM) of each of paclitaxel, and conjugates. Another set of cells were pulse-treated at 2.4 microM, 4.8 microM and 9.6 microM concentrations of each of these drugs for 4 h and the recovered cells were examined after 72 h. Control cultures received only the solvents (dimethyl sulfoxide or water). Our results showed a significant increase in the frequencies of telomeric associations, chromosome aberrations, polyploidization, distorted and disintegrated chromosome morphology, and reduced telomeric signal intensity by fluorescence in situ hybridization, in treated cultures as compared to the controls. However, we detected no change in telomerase activity. In addition, the majority of interphase nuclei in treated cells showed apoptotic bodies, with chromatin condensation. These in vitro results suggest that cell death induced by paclitaxel and its water-soluble conjugates is due to the loss of telomeric repeats, as shown by reduced signal flourescence and increased telomeric associations.

Animals↗

PubMedDate not supplied

Conventional cytogenetics alone is not sufficient for identifying interspecies cell line contamination.

Evidence from our laboratory suggests that conventional chromosome banding analysis alone is not sufficient for detecting interspecies contamination of cell lines. To differentiate noncycling interphase cells of murine or other species origin that may be contaminating a human cell line, molecular cytogenetic techniques such as fluorescence in situ hybridization (FISH) with a total human DNA probe must be used.

Animal Population Groups↗

PubMedDate not supplied

Genetic alterations in human prostate cancer: a review of current literature.

We review the literature dealing with genetic alterations in human prostate cancer. We also discuss genetic predisposition and the roles of various proto-oncogenes and tumor-suppressor genes in prostate cancer initiation, progression, and metastasis. The role of telomere dynamics in prostate cancer metastasis and the induction of apoptosis is also briefly discussed.

Adenocarcinoma↗

PubMedDate not supplied

Clastogenic interactions between lobeline sulfate and ethyl alcohol: a cytogenetic study.

The clastogenicity of lobeline and possible interactions between lobeline and ethyl alcohol were investigated in a mutagen-sensitivity assay on cultures of human lymphoblastoid cell lines. Lobeline (10(-6) M) and ethyl alcohol (1% and 2%) were added to the cultures alone or in different combinations prior to or simultaneously with bleomycin treatment. The number of chromatid breaks per cell served as the indicator of clastogenicity. Lobeline alone was not clastogenic, but there was a marked increase in genetic damage resulting from a coclastogenic interaction between lobeline and ethyl alcohol. These data emphasize the significance of interactions between compounds that may increase genotoxicity in cells exposed to mutagenic environments.

Bleomycin↗