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At least 685 records · Page 38Linked to original sources
PubMed1998

Prognostic value of cytogenetics in multiple myeloma.

Karyotypic studies of bone marrow were conducted in 79 previously untreated patients with multiple myeloma who received a standard programme of chemotherapy. An abnormal karyotype was observed in 46% of patients, virtually all showing multiple abnormalities consistent with a long period of preclinical clonal evolution. Patients with an abnormal pattern showed various aberrations with hyperdiploidy in 64%, pseudodiploidy in 5% and hypodiploidy in 31%. The number of chromosomes affected ranged from two to 19 (median 10), with at least one trisomy in 83%, one monosomy in 75%, and one translocation in 42% of patients. Lymphoma-like karyotypes were present in 17% of patients with an abnormality but were not associated with atypical clinical features, such as an extramedullary mass, leukaemia, or increased serum lactate dehydrogenase. Monosomy or deletion of chromosome 13 was present in 47% of patients with an abnormal pattern, who lived for a shorter duration (median 10 months) than patients with other abnormalities (median 34 months) or with diploidy (median 35 months). The cause of the short survival of patients with monosomy or deletion of chromosome 13 was not clear, but further studies on the relationship with specific oncogenes are indicated.

Bone Marrow Cells↗
PubMed1999

Clonal selection of CD56+ t(8;21) AML blasts: further suggestion of the adverse clinical significance of this biological marker?

Although patients with acute myelogenous leukaemia (AML) and t(8;21)(q22;q22) have a favourable prognosis, a subset die despite receiving appropriate treatment. Recent reports suggest that expression of the CD56 antigen might predict for both extramedullary disease and poor outcome in these patients. We describe a patient who presented with CD56-negative t(8;21) AML who achieved a complete remission and was subsequently treated with three consolidative courses of high-dose cytarabine therapy. She relapsed 9 months later with extramedullary and bone marrow involvement of CD56-positive t(8;21) AML. This case demonstrates clonal evolution and provides further support that blast expression of CD56 might be an unfavourable prognostic factor in t(8;21) AML.

Adult↗
PubMed2000

p53 intronic point mutation, aberrant splicing and telomeric associations in a case of B-chronic lymphocytic leukaemia.

We report a case of chronic lymphocytic leukaemia (CLL) with telomeric associations and a p53 intronic point mutation. Karyotypic analysis revealed clonal and non-clonal telomeric associations, accompanied by clonal cytogenetic abnormalities and also in isolation. The p53 mutation, which occurred at the invariant base pair -2 of the splice acceptor site in intron 7 resulted in the abolition of correct splicing of exon 7 to exon 8. Multiple aberrant splice products were characterized, all of which differed from wildtype in the DNA binding domain. Fluorescence in situ hybridization demonstrated that the clone retained two copies of the p53 gene and wild-type p53 transcript was detected on cloning of reverse transcriptase polymerase chain reaction (RT-PCR) product, indicating that one wild-type allele remained. However, a plasmid clone with correct splicing at the exon 7/8 boundary, but with a 21 bp deletion in exon 8, was also found at low frequency. This finding indicates clonal evolution, resulting in complete loss of wild-type p53. The intronic point mutation was not present in DNA extracted from cervical tissue indicating that it was a leukaemic phenomenon. This is the first case of an intronic point mutation to be reported in CLL. This mutation led to chaotic p53 expression and, interestingly, occurred in a case showing telomeric associations, a rare phenomenon in B-CLL.

Amino Acid Sequence↗
PubMed2000

Absence of mutations in the granulocyte colony-stimulating factor (G-CSF) receptor gene in patients with myelodysplastic syndrome/acute myeloblastic leukaemia occurring after treatment of aplastic anaemia with G-CSF.

The development of myelodysplastic syndrome/acute myeloblastic leukaemia (MDS/AML) has been reported in patients with aplastic anaemia (AA) after administration of recombinant human granulocyte colony-stimulating factor (rhG-CSF). Similarly, patients with severe congenital neutropenia (SCN) have an increased risk of developing MDS/AML after treatment with rhG-CSF. Point mutations in the G-CSF receptor gene are found in about 20% of SCN patients who are predisposed to MDS/AML. We investigated the occurrence of mutations in the G-CSF receptor in eight patients with AA who developed MDS/AML. No mutations were detected around the cytoplasmic domain of the gene in our patients, indicating that the mechanisms of clonal evolution to MDS/AML in patients with AA might be different from those with SCN.

Adult↗
PubMed2001

Multicolour spectral karyotyping identifies new translocations and a recurring pathway for chromosome loss in multiple myeloma.

Multicolour spectral karyotyping (SKY) was performed on primary tumour specimens from 100 patients with multiple myeloma (MM) that showed complex clonal chromosome aberrations not fully characterized by G-banding. In this study, SKY was able to identify or revise translocations with breakpoints involving 14q32, 11q13 or 8q24 in 32 patients (32%). Five new recurring translocations were identified, two of which involved chromosome 22. A subtle reciprocal translocation t(14;22) (q32;q11 approximately 12) was identified using SKY in two patients and a second, much larger, translocation t(11;22)(q13;q13) was identified using G-banding in three patients. A third new translocation was identified in two patients using SKY and G-banding as der(7)t(7;7)(p15 approximately 22;q22 approximately 32). Twenty-three patients (23%) showed the loss of 8p by whole-arm translocations with different whole-arm donor chromosomes. Among this group, two new recurring whole-arm translocations involving the centromeric breakpoint 8q10 were identified as der(8;20)(q10;q10) and der(8;18) (q10;q10) in three patients each. In addition, a novel pattern of three-way translocations involving the clonal evolution of the t(8;22)(q24;q11) by the subsequent loss of 8p by whole-arm translocations was found in three patients. The chromosome instability identified here demonstrates that the loss of 8p can occur by multiple whole-arm translocations, indicating a new pathway for the loss of a specific chromosome region in MM.

Chromosome Deletion↗
PubMed2001

Cytogenetic findings and their clinical relevance in myelofibrosis with myeloid metaplasia.

The prognostic significance of bone marrow cytogenetic lesions in myelofibrosis with myeloid metaplasia (MMM) was investigated in a retrospective series of 165 patients. An abnormal karyotype was demonstrated in 57% of patients. At diagnosis (n = 92), 48% of the patients had detectable cytogenetic abnormalities, and clonal evolution was frequently demonstrated in sequential studies. More than 90% of the anomalies were represented by 20q-, 13q-, +8, +9, 12p-, and abnormalities of chromosomes 1 and 7. Of these, 20q-, 13q- and +8 were the most frequent sole abnormalities, each occurring in 15-25% of the abnormal cases. Trisomy 9 and abnormalities of chromosomes 1 and 7 were equally prevalent but were usually associated with additional cytogenetic lesions. Chromosome 5 abnormalities were infrequent but were over-represented in the group of patients exposed to genotoxic therapy. In a multivariate analysis that incorporated other clinical and laboratory variables, the presence of an abnormal karyotype did not carry an adverse prognosis. Instead, +8, 12p-, advanced age and anaemia were independent prognostic determinants of inferior survival. In particular, survival was not adversely affected by the presence of either 20q- or 13q-.

Adult↗
PubMed2003

Multicolour fluorescence in situ hybridization analysis of t(14;18)-positive follicular lymphoma and correlation with gene expression data and clinical outcome.

In order fully to identify secondary chromosomal alterations, such as duplications, additions and marker chromosomes that remained unresolved by G banding, 60 cases of t(14;18)-positive follicular lymphoma (FL) were analysed by multicolour karyotyping techniques [multicolour fluorescence in situ hybridization (MFISH)/multicolour banding for chromosome 1 (MBAND1)]. A total of 165 additional structural chromosomal aberrations were delineated. An increased frequency of chromosomal gains involving X, 1q, 2, 3q27-q29, 5, 6p11-p21, 7, 8, 11, 12, 14q32, 17q, 18 and 21 and deletions of 1p36, 3q28-q29, 6q, 10q22-q24 and 17p11-p13 was revealed by the MFISH/MBAND1 analysis. Balanced translocations other than t(14;18) were uncommon, whereas unbalanced translocations were numerous. Deletion of 1p36 and duplication of 1p33-p35, 1p12-p21 and 1q21-q41 were regularly involved in chromosome 1 alterations, seen in 53% of the cases. A strong correlation was demonstrated between gains of individual chromosomal bands and increased gene expression, including 1q22/MNDA, 6p21/CDKN1A, 12q13-q14/SAS, 17q23/ZNF161, 18q21/BCL2 and Xq13/IL2RG. Unfavourable overall survival was associated with del(1)(p36) and dup(18q). These data support the notion that translocation events are primarily responsible for FL disease initiation, whereas the unbalanced chromosomal gains and losses that mirror the gene expression patterns characterize clonal evolution and disease progression, and thus provide further insights into the biology of FL.

Adult↗
PubMed1996

Mammary fibroadenoma and some phyllodes tumour stroma are composed of CD34+ fibroblasts and factor XIIIa+ dendrophages.

Fibroadenomas and mammary phyllodes tumour arise by proliferation of mammary stroma and epithelial elements. However, it is the stromal element that determines the biology of these biphasic tumours. Normal mammary stroma, like most collagenous connective tissue, contains resident populations of CD34+ dendritic interstitial cells and scattered factor XIIIa+ collagen-associated dendrophages. Actin+myofibroblasts are usually absent from mammary stroma in non-disease states. To determine whether CD34+ and factor XIIIa+ cells proliferate in fibroadenomas and phyllodes tumours, and to study myofibroblastic differentiation in these lesions, we examined 19 fibroadenomas in 14 patients along with five low grade and two high grade phyllodes tumours. We employed antibodies against the human progenitor cell antigen CD34, coagulation factor XIIIa and HHF-35 actin. In three fibroadenomas and two phyllodes tumours, we used Ki-67 antigen to study cell proliferation and oestrogen and progesterone receptors to study possible hormonal influence on stromal cells. In all fibroadenomas, CD34 strongly stained interlobular, pericanalicular and intracanalicular fibroblasts with collagenous and/or myxoid features. Four low grade phyllodes tumours also had CD34+ fibroblasts as did one high grade tumour. Actin reactivity varied and was most pronounced in six fibroadenomas resembling the so-called cellular variant, while seven regular fibroadenomas had no actin+stromal cells and six had only focal and weak actin+stromal cells. Factor XIIIa+ cells were prominently admixed in the stroma of all tumours studied comprising from 5% to 20% in fibroadenomas and, focally, up to 50% in phyllodes tumours. Oestrogen and progesterone receptors were expressed only in glandular elements. Ki-67 index in stromal cells was 1% to 3% in fibroadenoma, 10% to 20% in low grade, and 20% to 40% in high grade phyllodes tumour. We conclude that fibroadenomas and some phyllodes tumours are composed of CD34+ fibroblasts that show varying myxoid, collagenous or myofibroblastic differentiation. The fibroblasts are accompanied by a subset of dendritic histiocytes that express factor XIIIa. Fibroadenoma variants show prominent collagenous actin+myofibroblastic differentiation of CD34+ stromal cells, sometimes with a gradient of CD34 down-regulation. Fine-needle or limited stereotactic core biopsy of these biphasic tumours, if they yield only stromal cells, must be distinguished from other CD34+ stromal tumours. Increased factor XIIIa+ dendrophage populations were seen in phyllodes tumours, especially in two high grade tumours that had malignant fibrous histiocytoma-like features, suggesting clonal evolution toward the fibrohistiocytic final pathway. Further study of CD34 and factor XIIIa+ mammary stromal cells in larger numbers of phyllodes tumours might ascertain whether increasing factor XIIIa reactivity correlates with differentiation and increased tumour aggressiveness.

Adult↗
PubMed2002

Renal cell carcinoma with rhabdoid features: an aggressive neoplasm.

AIMS: Only a few reports on renal cell carcinoma with rhabdoid features have been published. This study was performed to investigate the clinicopathological characteristics of renal cell carcinomas with rhabdoid features. METHODS AND RESULTS: Among 253 cases of renal cell carcinoma in adults, eight cases with rhabdoid features were detected. Rhabdoid areas ranged from 10% to 90% of each of the cases. Seven of the eight cases were TNM stage III or IV, and four of the eight cases died within 8 months of surgery. Immunohistochemically, the rhabdoid areas were positive for CAM 5.2 (4/8), AE1/AE3 (6/8), epithelial membrane antigen (6/8) and vimentin (8/8), and negative for myogenetic markers (0/8). The mean MIB-1 labelling index in the rhabdoid areas was higher than that in the definite carcinomatous areas. Ultrastructurally, perinuclear whorls of intermediate filaments were demonstrated in three of the eight cases using paraffin-embedded blocks. CONCLUSIONS: The rhabdoid areas in renal cell carcinoma have histological, immunohistochemical and ultrastructural similarities to malignant rhabdoid tumours. Renal cell carcinoma with rhabdoid features is a highly aggressive neoplasm and its malignant behaviour may be due to the high cell-proliferative activity of the rhabdoid areas. Rhabdoid features in renal cell carcinoma may represent the endpoint of clonal evolution of renal cell carcinoma (especially in clear cell type cases).

Aged↗
PubMed2001

Ovarian carcinoma recurring as carcinosarcoma.

Malignant mixed mesodermal tumor is a rare tumor of the ovary and its histogenesis is controversial. We report the case of an ovarian tumor that seemed to be a pure carcinoma and recurred as a carcinosarcoma, and suggest a possible histogenesis for this kind of tumor. The patient was a 62-year-old Japanese woman. The primary tumor was confined to the right ovary and was a histologically poorly differentiated endometrioid adenocarcinoma with focal squamous differentiation. The tumor recurred as peritoneal dissemination 9 months later showing a histological appearance of carcinosarcoma of heterologous type. The recurrent tumor also contained intermingled foci of similar histology as the primary tumor. The carcinomatous component of the recurrent tumor showed more obvious differentiation to adenocarcinoma with increased expression of epithelial markers compared to the primary tumor. Epithelial membrane antigen was positive also in a few cells of the sarcomatous component, which implies that this tumor had features of metaplastic carcinoma. The DNA ploidy pattern of the primary ovarian tumor was diploid, while an additional aneuploid subpopulation appeared in the recurrent tumor. These findings suggest the possible histogenesis of carcinosarcoma of the ovary as progression and clonal evolution of endometrioid adenocarcinoma.

Carcinoma, Endometrioid↗
PubMed2001

Overview. Cytogenetic analysis in haematology.

Cytogenetic analysis has contributed greatly to our understanding of the nature of leukaemia and lymphoma. Study of these two groups of diseases has revealed general truths about the nature of the neoplastic process. Cytogenetic analysis has demonstrated that haematological neoplasms result from a somatic mutation occurring in a haemopoietic, lymphoid or multipotent stem cell. Complete remission has been related to disappearance of the clone of cells bearing the mutation whereas the occurrence of clonal evolution has often been found to be indicative of increasingly aggressive disease. Cytogenetic analysis of leukaemias and lymphomas has led to the discovery of numerous proto-oncogenes; these generally play a crucial role in proliferation and differentiation of normal cells with a perturbation of their function leading to neoplasia. In addition, cytogenetic evidence has suggested a role for loss of function of cancer-suppressing genes in haematological neoplasms. Cytogenetic analysis has also made major contributions to precise diagnosis and to the assigning of prognosis and, furthermore, by identifying good and poor prognostic groups has improved the management of patients. Good-prognosis patients have been spared unnecessary treatment and, conversely, more intensive treatment for some diseases associated with a cytogenetic abnormality that was previously indicative of a poor prognosis has improved the outcome for these patients.

Chromosome Aberrations↗
PubMed2002

Atypical blasts and bone marrow necrosis associated with near-triploid relapse of acute promyelocytic leukemia after arsenic trioxide treatment.

The pathologic features of acute promyelocytic leukemia (APL) with t(15;17)(q22;q21) are highly characteristic, which with few exceptions enable a firm diagnosis to be made on morphologic grounds. An APL patient in first relapse presented with large, bizarre circulating blasts and bone marrow necrosis 2 weeks after chemotherapy consolidation for an arsenic trioxide-induced remission. Although a morphologic diagnosis could not be reached, cytogenetic investigations showed a near-triploid clone with t(15;17), confirming APL in second relapse. This case showed that clonal evolution with additional karyotypic aberrations might alter the blast morphology and pathologic features in APL.

Adult↗
PubMedDate not supplied

[DNA-ploidy and proliferation in metastatic neuroblastoma].

Nuclear DNA contents of tumor cells were measures by fluorescence cytophotometry in bone marrow and touch preparations of 26 children with neuroblastoma, registered in the NBL79 study of the German Pediatric Oncology society. In all cases tumor cells were found to have a higher DNA-content as compared to the normal diploid (2c) DNA-value of granulocytes in the same preparation. Average ploidy values of the histograms of bone marrow metastases were in the tetra- to hypertetraploid (4c-5c) range and showed unimodal distribution in the majority of cases. In the primary tumors there was also a wide distribution of DNA-values in the aneuploid range. A bimodal distribution with stemlines at 2,5c and 5c was found in a stage I, grade I, differentiated primary tumor. Various ploidy patterns found at different sites in the large tumor mass of a newborn might be interpreted as an expression of different degrees of differentiation within the same tumor. In 2 of 4 patients where primary tumor and metastatic lesions could be examined there was a higher ploidy in the 5c to 6c, or even in the 8c range in the metastatic cell population. It appears, thus, that clonal evolution of tumor cells occurs during growth and spread of neuroblastoma.

Bone Marrow↗
PubMed2005

V600E B-Raf requires the Hsp90 chaperone for stability and is degraded in response to Hsp90 inhibitors.

The Raf family includes three members, of which B-Raf is frequently mutated in melanoma and other tumors. We show that Raf-1 and A-Raf require Hsp90 for stability, whereas B-Raf does not. In contrast, mutated, activated B-Raf binds to an Hsp90-cdc37 complex, which is required for its stability and function. Exposure of melanoma cells and tumors to the Hsp90 inhibitor 17-allylamino-17-demethoxygeldanamycin results in the degradation of mutant B-Raf, inhibition of mitogen-activated protein kinase activation and cell proliferation, induction of apoptosis, and antitumor activity. These data suggest that activated mutated B-Raf proteins are incompetent for folding in the absence of Hsp90, thus suggesting that the chaperone is required for the clonal evolution of melanomas and other tumors that depend on this mutation. Hsp90 inhibition represents a therapeutic strategy for the treatment of melanoma.

Animals↗
PubMed2001

p63 identifies keratinocyte stem cells.

The proliferative compartment of stratified squamous epithelia consists of stem and transient amplifying (TA) keratinocytes. Some polypeptides are more abundant in putative epidermal stem cells than in TA cells, but no polypeptide confined to the stem cells has yet been identified. Here we show that the p63 transcription factor, a p53 homologue essential for regenerative proliferation in epithelial development, distinguishes human keratinocyte stem cells from their TA progeny. Within the cornea, nuclear p63 is expressed by the basal cells of the limbal epithelium, but not by TA cells covering the corneal surface. Human keratinocyte stem and TA cells when isolated in culture give rise to holoclones and paraclones, respectively. We show by clonal analysis that p63 is abundantly expressed by epidermal and limbal holoclones, but is undetectable in paraclones. TA keratinocytes, immediately after their withdrawal from the stem cell compartment (meroclones), have greatly reduced p63, even though they possess very appreciable proliferative capacity. Clonal evolution (i.e., generation of TA cells from precursor stem cells) is promoted by the sigma isoform of the 14-3-3 family of proteins. Keratinocytes whose 14-3-3final sigma has been down-regulated remain in the stem cell compartment and maintain p63 during serial cultivation. The identification of p63 as a keratinocyte stem cell marker will be of practical importance for the clinical application of epithelial cultures in cell therapy as well as for studies on epithelial tumorigenesis.

3T3 Cells↗
PubMed2000

Chromosomal breakage-fusion-bridge events cause genetic intratumor heterogeneity.

It has long been known that rearrangements of chromosomes through breakage-fusion-bridge (BFB) cycles may cause variability of phenotypic and genetic traits within a cell population. Because intercellular heterogeneity is often found in neoplastic tissues, we investigated the occurrence of BFB events in human solid tumors. Evidence of frequent BFB events was found in malignancies that showed unspecific chromosome aberrations, including ring chromosomes, dicentric chromosomes, and telomeric associations, as well as extensive intratumor heterogeneity in the pattern of structural changes but not in tumors with tumor-specific aberrations and low variability. Fluorescence in situ hybridization analysis demonstrated that chromosomes participating in anaphase bridge formation were involved in a significantly higher number of structural aberrations than other chromosomes. Tumors with BFB events showed a decreased elimination rate of unstable chromosome aberrations after irradiation compared with normal cells and other tumor cells. This result suggests that a combination of mitotically unstable chromosomes and an elevated tolerance to chromosomal damage leads to constant genomic reorganization in many malignancies, thereby providing a flexible genetic system for clonal evolution and progression.

Chromosome Aberrations↗
PubMed1986

Natural populations of Trypanosoma cruzi, the agent of Chagas disease, have a complex multiclonal structure.

We have studied 15 gene loci coding for enzymes in 121 Trypanosoma cruzi stocks from a wide geographic range--from the United States and Mexico to Chile and southern Brazil. T. cruzi is diploid but reproduction is basically clonal, with very little if any sexuality remaining at present. We have identified 43 different clones by their genetic composition; the same genetic clone is often found in very distant places and in diverse hosts. There is much genetic heterogeneity among the different clones, and they cannot be readily classified into a few discrete groups that might represent natural taxa. These findings imply that the biological and medical characteristics need to be ascertained separately for each natural clone. The evidence indicates that clonal evolution is very ancient in T. cruzi. We propose two alternative hypotheses concerning the relationship between the biochemical diversity and the heterogeneity in other biological and medical characteristics of T. cruzi. One hypothesis is that the degree of diversity between strains simply reflects the time elapsed since their last common ancestor. The second hypothesis is that biological and medical heterogeneity is recent and reflects adaptation to different transmission cycles. A decision between the two hypotheses can be reached with appropriate studies, with important medical consequences.

Alleles↗
PubMed1999

Comparative genomic hybridization, loss of heterozygosity, and DNA sequence analysis of single cells.

A PCR strategy is described for global amplification of DNA from a single eukaryotic cell that enables the comprehensive analysis of the whole genome. By comparative genomic hybridization, not only gross DNA copy number variations, such as monosomic X and trisomic 21 in single male cells and cells from Down's syndrome patients, respectively, but multiple deletions and amplifications characteristic for human tumor cells are reliably retrieved. As a model of heterogeneous cell populations exposed to selective pressure, we have studied single micrometastatic cells isolated from bone marrow of cancer patients. The observed congruent pattern of comparative genomic hybridization data, loss of heterozygosity, and mutations as detected by sequencing attests to the technique's fidelity and demonstrates its usefulness for assessing clonal evolution of genetic variants in complex populations.

Bone Marrow Cells↗