1,721,052 research outputs found
Digoxigenin-labeled probes can detect single-copy genes in human metaphase chromosomes
No full textA technique of in situ hybridization on metaphases of chromosomes by a digoxigenin-labeled probe is described. This technique was able to detect single DNA sequences of 2 and 7 kilobases. The results obtained were compared with those of a biotin streptavidin alkaline phosphatase-based detection system. The digoxigenin method was at least as efficient and sensitive as the biotin-streptavidin method
The DNA mismatch repair and the formation of chromosomal aberrations after bleomycin tretament.
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Fragile site induction by aphidicolin may be increased in parents of neuroblastoma patients
No full textWe recently demonstrated an increased expression of fragile sites, induced by aphidicolin, in lymphocytes of neuroblastoma patients. We have now extended our studies to parents of affected children with neuroblastoma to verify if this characteristic may be genetically transmitted. We have examined 20 families. In most of them, the hypersensitivity to aphidicolin was found in the affected child and in at least one parent. Moreover, some of the parents showed an increase in the expression of the fragile sites 1p32, 1p13, or both that are preferentially expressed in neuroblastoma patients. The possible relations between the hypersensitivity to aphidicolin and the inheritance of predisposition to neuroblastoma must be clarified
Role of mismatch repair in the induction of chromosomal aberrations and sister chromatid exchanges in cells treated with different chemotherapeutic agents
No full textThe mismatch repair (MMR) system plays a major role in mediating the cytotoxicity and clastogenicity of agents generating O(6)-methylguanine in DNA. Loss of MMR has also been associated with tumor cell resistance to the cytotoxic effects of 6-thioguanine and cisplatin and with hypersensitivity to N-(2-chloroethyl)- N'-cyclohexyl- N-nitrosourea (CCNU). The aim of the present investigation was to elucidate the role played by the MMR system in the generation of chromosomal damage in cells exposed to 6-thioguanine, cisplatin or CCNU
Apoptotic and clastogenic effects of methylating agents, alone or combined with poly(ADP-ribose) polymerase inhibitor, in peripheral blood lymphocytes
No full textWe recently demonstrated that mismatch repair deficient tumor cells, that are tolerant to O6-methyl guanine (O6meG) damage, are susceptible to MeOSO2(CH2)2-lexitropsin (Me-Lex) capable of inducing almost exclusively N3-methyl adenine (N3meA) adducts. Moreover, these cells can be rendered sensitive to O6methylating agents that generate low levels of N3meA (temozolomide, TZM), when used in combination with poly(ADP-ribose) polymerase (PARP) inhibitors. This is likely due to interruption of base excision repair (BER) process, that is involved in nucleotide replacement of N3meA. PARP inhibitors are also capable of enhancing the cytotoxic and clastogenic effects induced by Me-Lex. Purpose To evaluate the potential toxicity and clastogenicity in normal peripheral blood lymphocytes (PBL) of Me-Lex or TZM, as single agent or associated with PARP inhibitor. Methods and results PBL of healthy donors, untreated or activated with PHA for 3h, were exposed to graded concentrations of Me-Lex (1.5-25M) or TZM (62.5-250M), alone or combined with the PARP inhibitor 3-aminobenzamide (AB, 4mM). Cytotoxicity was evaluated at daily intervals during 72h of culture. Chromosome damage was assessed only in PHA-activated PBL at 72h. The results show that: a) when used alone, Me-Lex induced apoptosis in a dose-dependent fashion, either in non-stimulated or in PHA-activated PBL as early as 24h after treatment. Addition of AB significantly increased the percentage of apoptotic cells at all drug concentrations; b) in the case of TZM, at 24 h apoptosis was not observed either in resting or PHA-activated PBL. Only when the drug was combined with AB, a small percentage of apoptotic cells could be detected. In contrast, at 48 or 72h of culture, TZM induced apoptosis only in PHA activated PBL. This is likely the consequence of the toxicity derived from O6meG, that is known to occur after DNA replication. c) High concentrations of Me-Lex (12.5-25M) markedly reduced the mitotic index of PHA-activated cells and did not allow chromosome analysis. Me-Lex (1.5-3M) produced chromosome aberrations that were increased by addition of AB. TZM induced aberrations only at 250M and, when combined with AB, at all concentrations tested. d) MeLex (1-6M) induced sister chromatid exchanges (SCE) in a dose-dependent fashion and addition of AB significantly enhanced this effect. In the case of TZM, SCE were observed at all the concentrations tested. In the presence of AB, the number of SCE generated by TZM was significantly higher than that induced by the drug used alone or by Me-Lex ± AB. Conclusion High levels of N3meA or interruption of its repair through the use of PARP inhibitors might be toxic for effector cells of the immune system, including those mediating functions that do not require cell proliferation
Role of mismatch repair in the induction of chromosomal aberrations and sister chromatid exchanges in cells treated with different chemotherapeutic agents
No full textPurpose: The mismatch repair (MMR) system plays a major role in mediating the cytotoxicity and clastogenicity of agents generating O 6-methylguanine in DNA. Loss of MMR has also been associated with tumor cell resistance to the cytotoxic effects of 6-thio-guanine and cisplatin and with hypersensitivity to N-(2-chloroethyl)-N′ -cyclohexyl-N-nitrosourea (CCNU). The aim of the present investigation was to elucidate the role played by the MMR system in the generation of chromosomal damage in cells exposed to 6-thioguanine, cisplatin or CCNU. Methods: The MMR-proficient cell lines TK6 and HCT116/3-6, and their MMR-deficient counterparts MT1 and HCT116, were treated with 6-thioguanine, cisplatin or CCNU, and analyzed for cell growth inhibition and chromosomal damage. As a control, similar experiments were performed with the methylating agent temozolomide. Results: Cytotoxicity, chromosomal aberrations and sister chromatid exchanges induced by 6-thioguanine and temozolomide were significantly reduced in the MMR-deficient cell lines with respect to their MMR-proficient counterparts. In contrast, although conferring some protection against cytotoxicity, the loss of MMR did not affect cytogenetic damage induced by cisplatin. CCNU produced comparable levels of cytotoxicity, chromosomal aberrations and sister chromatid exchanges in both MMR-proficient and MMR-deficient cell lines. Conclusions: The MMR system is involved in the generation of chromosomal damage in cells exposed to 6-thioguanine. The system does not play a relevant role in the generation of chromosomal damage in cells treated with CDDP and does not confer protection against the clastogenic effects of CCNU, at least in the cell lines investigated
Presence of spectrin in untreated Friend erythroleukemic cells. Its accumulation upon treatment of the cells with dimethyl sulfoxide
No full textFriend leukemia cells (FLC) are nucleated erythroid precursors, and are markedly stimulated towards more advanced stages of differentiation by treatment with dimethyl sulfoxide (DMSO). The presence of spectrin, an erythrocyte membrane protein, has been investigated in untreated and in DMSO-treated FLC by indirect immunofluorescence and by analysis in SDS-polyacrylamide gel electrophoresis of low-ionic-strength cell extracts immunoprecipitated with a monospecific anti-spectrin serum. Spectrin is detectable in significant amounts in the "inducible" clones prior to DMSO stimulation, and accumulates 4- to 5-fold upon addition of this compound to the cultures. Spectrin accumulation occurs rather early (24 hours after cell seeding) and reaches its peak on the third day to decline thereafter. Semiquantitative determinations of spectrin amounts present in DMSO-stimulated 745A and A degree 1 cells on the third day after treatment were 2.4 X 10(5) and 3.0 X 10(5) molecules/cell, respectively. Spectrin is also detectable in very low amounts in an "uninducible" line of FLC, and is not accumulated upon DMSO treatment thereof, whereas treatment with hemin does cause a significant increase of spectrin-positive cells. These data indicate that spectrin is a convenient "early" marker for in vitro studies of erythropoiesis
Appearance of altered cell-surface fucosyl glycopeptides in concomitance with chromosomal alterations in the gross virus-infected pre-leukemic thymus of the rat
No full textThe appearance of a class of fast-eluting cell-surface glycopeptides that are encountered almost exclusively in malignant and certain pre-malignant cells was monitored in the course of leukemogenesis in the thymus of rats injected at birth with Gross leukemia virus. The altered glycopeptides appeared as early as 15 days after virus injection, when the animals were still clinically healthy and no histological signs of the disease were present in the thymus. Their amount was further increased at 30 days, and reached a maximum in the fully developed lymphoma. The development of this early phenotypic marker of malignancy appeared to be concomitant with that of chromosomal anomalies in the thymus. Since these anomalies are non-random, the existence of a causal relationship between the glycopeptide change and the loss of specific chromosomes might be hypothesized
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