Microchromosomes in human preleukemia and leukemia

Double minute chromosomes in acute myeloid leukemia and myelodysplastic syndrome: identification of new amplification regions by fluorescence in situ hybridization and spectral karyotyping

Double minute chromosomes (dmin) are small chromatin bodies consisting of genes amplified in an extrachromosomal location. dmins are uncommon in hematologic malignancies; they are seen primarily in acute myeloid leukemia, with amplification of the MYC oncogene or, less frequently, the MLL transcription factor. Nine patients with hematologic malignancies with dmin were seen at the Roswell Park Cancer Institute between 1985 and 2000; eight had acute myeloid leukemia and one a myelodysplastic syndrome. Fluorescence in situ hybridization (FISH) demonstrated MYC amplification on dmin in four patients, but MLL amplification was not seen. Spectral karyotyping showed that the dmin derived from chromosome 11 in one patient and from chromosome 19 in two others without MYC or MLL amplification; derivation from these chromosomes was confirmed by FISH with chromosome paint probes. The dmin of chromosome 11 origin hybridized to a bacterial artificial chromosome (BAC) RP11-112M22 that maps to 11q24.3 and is predicted to contain ETS1 and other markers, including D11S11351 and D11S4091. The dmin of chromosome 19 origin in one patient hybridized to BACs RP11-46I12 and RP11-110J19; in the other patient, these clones did not hybridize with the dmin, but were found to be amplified on a marker chromosome that was derived from chromosome 19 in that patient's cells. These BACs have been mapped to 19q12-19q13.1 and 19q11-19q13.1, respectively, and are predicted to contain the markers D19S409 and D19S919 and the gene for ubiquinol-cytochrome C reductase, Rieske iron-sulfur polypeptide1 (UQCRFS1). dmin originating from chromosome 19 have not been reported previously in hematologic malignancies.

Double minute chromosomes and myelodysplastic syndrome: a case report and literature review

Double minute chromosomes (dmin) occur in about 3.3-10.6% of acute leukemia, especially in the elderly. However, dmins are relatively rare in myelodysplastic syndrome (MDS). We describe a case of refractory anemia with excess blasts associated with complex cytogenetic abnormalities, dmins, and brief survival.

Amplified c-MYC sequences localized by fluorescence in-situ hybridization on double minute chromosomes in acute myeloid leukemias

Double minute chromosomes (dmin) are small acentric fragments frequently observed when karyotyping human tumor cells. They are considered the cytogenetic manifestation of gene amplification. The finding of dmin in leukemia is a rare event usually associated with progression of the disease and unfavorable prognosis. We present four patients affected by myeloid disorders with an abnormal karyotype and a variable number of dmin. In an attempt to clarify the origin of the dmin and the amplified gene, we utilized a fluorescent in-situ hybridization (FISH) technique and a panel of specific probes. The results of the analysis indicate that, although chromosomes 8 are apparently uninvolved, dmin retained c-MYC sequencs in three cases. By observing previously reported cases, we found that the majority of patients with myeloid disorders and dmin showed an amplified c-MYC gene, regardless of the chromosomal abnormalities. The FISH technique proved to be informative in demonstrating gene amplification in both metaphase and interphase cells. Finally, in the one patient carrying a 20q deletion, FISH allowed the detection of a previously unreported translocation between a 16p and the 20q-, confirming the ability of the technique to understand complex karyotypes.

Biphenotypic M0 acute myeloid leukemia with trisomy-4

We report here a rare case of biphenotypic M0 acute myeloid leukemia (AML) associated with trisomy 4. The literature of trisomy 4 in acute leukemia was reviewed. M2 and M4 AML are the most common FAB subtypes associated with trisomy 4. The clinical course of this entity is generally comparable with other non-trisomy 4 cases of AML. Despite the speculation made when first described, no specific environmental toxin has been found to be associated with this entity. C-kit oncogene has been mapped to chromosome 4 recently, and the role of this proto-oncogene in leukemogenesis of trisomy 4 associated leukemia should be further investigated.

Cytogenetic triclonality in acute myeloid leukemia: a morphologic, immunologic and in situ hybridization study

Cytogenetically unrelated clones are uncommon in hematologic malignancies. We report a case of acute myeloid leukemia, which consisted morphologically of two populations of small and large blasts demonstrating immunophenotypic heterogeneity. Cytogenetic analysis showed 3 karyotypically abnormal clones: 47,XY, +14/45,XY,dic(5;17)(q11;p11),14dmin, and a near-tetraploid clone. In situ hybridization showed that the near-tetraploid clone corresponded to the large blasts, and the near-diploid clones the small blasts, therefore demonstrating a direct relationship between cell size and DNA content. The diverse morphologic, immunologic and cytogenetic heterogeneity observed in our case suggested hematopoietic oligoclonality.

Localization of amplified MYC gene sequences to double minute chromosomes in acute myelogenous leukemia

Cytogenetic and molecular studies were performed on two dmin-bearing acute myelogenous leukemia (FAB-M2) samples. Both cases were characterized by complex karyotypes containing interstitial deletions of the long arm of chromosome 8 altering band 8q24.1, aberrations affecting the short arm of chromosome 17, and multiple double minute chromosomes (dmin). Using a 1.4 kb cDNA probe coding for the third exon of the MYC oncogene, DNA slot blots indicated MYC gene sequences were amplified in both samples. Fluorescence in situ hybridization using a 9.0 kb genomic probe for MYC was performed in one case and localized the amplified MYC gene sequences to the dmin. Neither patient achieved a complete remission using traditional induction chemotherapy. The complex karyology with amplification of MYC gene sequences appears to represent a poor prognostic subgroup of acute myelogenous leukemia.

A new myeloblastic leukemia cell line with double minute chromosomes. Induction of methotrexate resistance and dihydrofolate reductase gene amplification

To test the relationship between DMs and drug resistance in newly established AML cell lines, KY821, and its clone KY821A3, the latter had lost DMs during cloning, were cultured in increasing concentrations of MTX. KY821 became resistant against 2 x 10(-4) M MTX, whereas KY821A3 did against 2 x 10(-5) M MTX in a same period. Enhanced enzyme activities of DHFR were correspondent to the increased DMs numbers and DHFR gene amplification in both resistant clones. The amplified DHFR gene was located on DMs by in situ hybridization. These data indicated that the presence of DMs in KY821 would facilitate the acquisition of drug resistance.

Cloning of a non-c-myc DNA fragment from the double minutes of a human colon carcinoid cell line

The cell line COLO 320 DM, derived from an untreated human colon carcinoid tumor, was subcloned to obtain a population (Cl 11) with an average of 37 double minutes (DM) per cell. Fractionation of the chromosomes by differential centrifugation yielded a fraction enriched in DM. DNA isolated from the DM-enriched fraction was inserted into the Pst I site of pBR322. One clone, p446, representative of a number of similar clones, contained a region complementary to genomic unique sequences (region p446U). Southern blot analysis using COLO 320 DNA, and DNA from two other cell lines derived from the same biopsy, COLO 320 HSR and COLO 321 HSR, demonstrated amplification and rearrangement of sequences complementary to p446U when compared with 28 different tumor and normal cell lines, some of which contained DM or homogeneously staining regions (HSR). COLO 320 DM Cl 11 had approximately 110 copies per cell of the p446U sequence, or three copies per DM. COLO 320 HSR, which contained one HSR, had 35 copies per cell, while COLO 321 HSR, which contained two HSR, had 700 copies. In addition, p446U did not hybridize with insert sequences of recombinant plasmid pHM(E + H), which includes the human c-myc coding region, 3 kb of upstream flanking sequences and 0.5 kb of downstream flanking sequences, or with an exon 3 probe, pMYC RI-CLA. Amplification of p446U was also not seen in cell lines containing amplified c-myc or N-myc genes. These results indicate that more than one sequence may be amplified in DM or HSR containing tumor cells, but that they need not be amplified together in other tumors.

Gene amplification of c-myc and N-myc in small cell carcinoma of the lung

The relationship of the copy numbers of the c-myc and N-myc oncogenes to tumor formation and progression was studied in small cell carcinoma of the lung. When 96 neoplastic lesions from 45 patients were examined, these lesions could be grouped into three categories: high copy (tumors with greater than 3 copies of the N-myc or c-myc gene per haploid genome), middle copy (1.5 to 3 copies per genome), and normal copy. Fourteen of the patients had middle copy tumors, but this was almost always a result of chromosome duplication rather than the amplification of a small genetic locus. In contrast, five patients had high copy tumors, with the increased copy number in each case due to gene amplification. The amplification did not occur in a heterogeneous fashion within individual patients, since all metastatic lesions from patients with high copy lung tumors were also high copy, while none of 41 metastatic lesions from the other patients were high copy. These data suggest that gene amplification is an important step in neoplastic growth in a subset of patients with small cell carcinoma of the lung and that this genetic event occurs relatively early (before metastasis) in this subset.

Chromosome abnormalities in acquired idiopathic sideroblastic anemia with subsequent leukemic transformation

Chromosomal abnormalities were demonstrated in the bone marrow cultures of two patients with acquired idiopathic sideroblastic anemia (AISA). Both patients subsequently experienced leukemic transformation and developed acute myelomonocytic leukemia (type M4). A review of the literature revealed that approximately 40% of the AISA cases manifest chromosomal abnormalities, of which 20.5% underwent leukemic conversion.

Acute nonlymphocytic leukemia with severe hypodiploidy and one double minute chromosome

We present a case of acute nonlymphocytic leukemia with severe hypodiploidy (38 chromosomes), complex karyotype, and one double minute chromosome. These unusual chromosome findings could be related to the rapid course of the patient's disease.

Cytogenetic studies in 174 consecutive patients with preleukemic or myelodysplastic syndromes

Routine cytogenetic studies were done in 174 consecutive patients with preleukemic or myelodysplastic syndromes (PL/MDS): 5 had the 5q - syndrome, 2 had refractory cytopenia, 43 had refractory anemia, 38 had refractory anemia with ringed sideroblasts, 69 had refractory anemia with excess blasts, 6 had refractory anemia with excess blasts in transition, and 11 had chronic myelomonocytic leukemia. Successful chromosome studies were accomplished in 167 patients (96%); 64 (37%) had a chromosomally abnormal clone. Abnormal clones were most common among patients who had refractory anemia with excess blasts (45%), refractory anemia with excess blasts in transition (60%), and chronic myelomonocytic leukemia (45%); they were least common among patients with refractory anemia (32%) and refractory anemia with ringed sideroblasts (21%). The two patients with refractory cytopenia had normal cytogenetic results. Each patient with the 5q - syndrome had a 5q-chromosome, as this is a prerequisite for the diagnosis. The two most common structural abnormalities were deletion of part of a chromosome 5 long arm (17 patients) and deletion of part of a chromosome 20 long arm (8 patients). Nonspecific structural abnormalities of chromosomes 1, 3, 6, and 17 were also common. The most common numeric abnormalities were monosomy 5 (7 patients), monosomy 7 (4 patients), loss of the Y chromosome (9 patients), and trisomy 8 (20 patients). No chromosome abnormalities were specifically associated with any PL/MDS classification.

Double minutes in acute myeloid leukemia

Five out of 110 patients with acute myeloid leukemia (AML) showed double minutes (DM) in cytogenetic preparations. DM were found to occur predominantly in elderly patients, and in erythroleukemia or acute myelomonocytic leukemia. The five patients were apparently divided into two groups according to the number of DM per cell. Patients with few sets of DM had exclusively complex karyotypes and a poor prognosis while patients with numerous DM had otherwise normal or nearly normal karyotypes and a good prognosis. Data on 11 previously reported cases of AML with DM were collected from the literature and consistent results were revealed except that several of the 11 patients were diagnosed as having acute myeloblastic leukemia (M1 and M2 in the FAB classification), which is apparently due to differences in diagnostic criteria. Therefore, numerous or few DM in a cell might relate to different entities. When the number of DM was small they might have resulted from breakdown of existing chromosomes.

Chromosomes and causation of human cancer and leukemia. LI. A hairy cell leukemia case with 14q+ and ring chromosomes: significance of ring chromosomes in blood disorders

What appears to be the first hairy cell leukemia case with a 14q+ anomaly is described. In addition to the 14q+ anomaly, a 6q- and a ring chromosome were seen in a blood sample stimulated with lipopolysaccharide, a B-cell mitogen. The clinical course of the present case was short, stormy, and had a poor response to therapy. The correlation between the clinical course and the presence of a ring chromosome in myelo- and lymphoproliferative blood disorders is discussed in relation to the various blood disorders with this karyotype anomaly described in the literature.

Correlation between chromosomal pattern, cytological subtypes, response to therapy, and survival in acute myeloid leukaemia

Chromosomal karyotypes were determined with standard G-banding in 103 patients with acute myeloid leukaemia (AML). Abnormal clones were present in 52 (50.5%). Higher frequencies of abnormalities were observed in male than in female patients and in erythroleukaemia (EL) than in other subtypes of AML. Abnormalities were more frequent in myeloblastic (AMyL) than in myelomonocytic leukaemias (AMML) and mixtures of both normal and abnormal karyotypes were more common among elderly patients; these differences, though of marginal statistical significance, are consistent with previous reports. 9 of 10 cases with 5 or more aberrant chromosomes and 6 of 8 cases with unidentified marker chromosomes were either AMML or EL. Remission rates, median survivals and relative death rates were collated in 82 patients, in relation to the karyotype patterns NN (all normal), AN (mixed normal and abnormal) and AA (all abnormal). The differences between the groups did not reach statistical significance. Serial cytogenetic studies were performed in 10 patients. New karyotype changes emerged in only 1 of 6 relapses. 4 examples of t(8;21) and 2 of t(15;17) were found. 1 case of AMML showed trisomy 8 and double minute chromosomes. 1 case of EL showed 2 marker chromosomes with homogeneously staining regions.

Double-minute chromosomes in the leukocytes of a patient with a previous history of cervical carcinoma

Double-minute chromosomes (DMs) were observed in repeated samples in the leukocytes of a patient with a previous history of cervical carcinoma. The most interesting cytogenetic finding was the coexistence of DMs and a dicentric chromosome along with chromosome- and chromatid-type breaks and gaps. This observation suggests that DMs might originate through the breakage of existing chromosomes. The presence of DMs in leukocytes may also indicate the possibility that certain common agents cause DMs in tumor cells as well as in normal cells.

Coincidence of cytogenetic markers in four murine cell lines

Foreign body tumorigenesis was induced by the subcutaneous implantation of a plastic or glass cylinder in BALB/c mice; the inoculation of human neoplastic cells significantly increased the incidence of these anaplastic sarcomas. Of 15 tumors studied, four presented the same markers: one induced with and three without human neoplastic cell inoculation within the foreign body. The markers observed were double minutes (DM), a long acrocentric marker (MLA), and a metacentric marker (MM). The DM are a number of small often tiny chromosomal structures appearing in pairs together with chromosomes of ordinary size. MLA is a long acrocentric derived from a translocation in tandem between chromosomes #1 and #16. MM is due to centric fusion of two chromosomes #10. Numerical anomalies consisted of gains of the same chromosomes types. It is postulated that these coincident findings are related to the foreign-body tumorigenesis.

Gene-amplification model of carcinogenesis

A two-stage model of carcinogenesis is proposed based on recent evidence for the occurrence of proto-oncogenes in the vertebrate genome, evidence for gene amplification during carcinogenesis, and studies of the action of tumor promoters. The model is baed on the view that an increase in the level of gene product from such proto-oncogenes is sufficient to induce neoplastic transformation. It proposes that the initial step in carcinogenesis (initiation) is a mutation producing a tandem duplication of a proto-oncogene. Gene amplification can then occur by successive unequal sister chromatid crossing-over events in several cell cycles until sufficient gene product is produced to transform the cell.

Acute non-lymphocytic leukemia and acute myeloproliferative syndrome following radiation therapy for non-Hodgkin's lymphoma and chronic lymphocytic leukemia: cytogenetic studies

Seven cases of acute nonlymphocytic leukemia (ANLL) and one of malignant myeloproliferative syndrome were identified from a pool of 189 cases of non-Hodgkin's lymphoma (NHL) and CLL treated primarily with extensive radiotherapy at the Clinical Center, the National Institutes of Health. Four patients also received chemotherapy, two for only short periods. The median time interval from the diagnosis of the primary malignancy to the development of leukemia was 61 months (range 33 to 98 months) and the median survival after the diagnosis of leukemia was two months (0 to 9 months). All eight patients were cytogenetically abnormal and serial chromosome studies revealed that hypodiploidy was the most commonly observed chromosomal abnormality. Abnormalities of chromosome no. 7 were seen in all five patients analyzed by the chromosome banding technique; four of them had monosomy 7. The next most frequently involved chromosome was no. 5. The complexity, extensive nature, and long duration of the cytogenetic abnormalities prior to the diagnosis of leukemia in these patients may be characteristic of secondary leukemia in radiation-treated lymphoma and the presence of such anomalies may predict leukemic transformation.

New aspects of preleukemic disorders

Preleukemic disorders are a controversial group of panmyelopathic disturbances that often precede the emergence of acute myeloblastic or myelomonocytic leukemia. In most instances, these preleukemic disorders are characterized by slowly developing myeloblastosis of the bone marrow. They include preleukemia, primary acquired panmyelopathy with myeloblastosis or smouldering acute leukemia, erythroleukemia, and subacute myelomonocytic leukemia. Sometimes, transitions between these various preleukemic disorders may be observed in a single individual. Abnormalities in cellular differentiation are expressed in cytochemical aberrations and in elaboration of colony forming units by marrow cells of patients with preleukemic disorders. Cytogenic and cellular kinetic abnormalities link preleukemic disorders closely to acute myeloblastic or myelomonocytic leukemia, although in many patients with preleukemic disorders, conversion to acute leukemia is not observed or perhaps not recognized. Understanding pathogenetic and pathophysiological aspects of preleukemic disorders may shed light on aspects of cellular proliferation and cellular differentiation in the acute leukemias.

Cytogenetic studies in preleukaemia using the G-banding staining technique

15 patients with preleukaemia were cytogenetically studied during the preleukaemic state by using the G-banding staining technique. It was found that 9 patients had a completely normal karyotype, while the other 6 showed various chromosomal abnormalities, numerical (trisomies in 5 cases) and structural (deletion in 1 case and a marker chromosome in 1 case). The abnormalities concerned group C in all 6 cases, while group A was involved in 3 cases. G-banding technique revealed that trisomy C affected the chromosomes nos 8 (2 cases) and 9 (3 cases); also a deleted chromosome 11 (11q-) was identified in 1 case and a marker chromosome in 1, the origin of which was established as a translocation between chromosomes 3 and 6. The abnormalities of group A concerned chromosome no 3. The abnormalities found in our cases, using the G-banding technique, were similar to those described in acute leukaemia.

Cytogenetic studies and clinical implications in patients with Sézary syndrome

Chromosome studies were carried out on 11 National Institutes of Health (N.I.H.) patients who had the diagnosis of Sézary syndrome. Heteroploidy, multiple markers including minute and ring chromosomes, and a lack of modality and clone formation, were the common chromosomal findings in this syndrome. Abundant spontaneous division of heteroploid cells in unstimulated peripheral blood cultures, a high percentage of heteroploid cells in stimulated culture, and finally, clone formation, are signs of a fulminant process and lead to the terminal phase of this disease. Early chemotherapeutic eradication of these heteroploid neoplastic cells would, therefore, be the treatment of choice in this disease.

Periodontal disease associated with preleukemic syndrome

A case of preleukemic syndrome associated with severe periodontal disease has been presented for the first time. The clinical, radiographic and hematologic findings have been discussed, as well as medical and periodontal therapy.

Cytogenetic studies in acute lymphocytic leukemia: special emphasis in long-term survival

Cytogenetic studies were performed in 331 patients with ALL diagnosed at the National Institutes of Health between January 1961 and January 1976. Four patients had constitutionally abnormal genotypes, three had Down's syndrome, and one had a D/G translocation. Aneuploidy was observed in the pretreatment bone marrow in 49/115 (42.6%) of this series exhibited several general characteristics: aneuploid cells usually coexist with normal stem cells, hyperdiploidy is predominant and wide ranging aneuploidy clusters around a major cell line. The most common chromosomal group involved in aneuploidy is the G group (p=0.001) and the next most common is the B group (p=0.01). Aneuploidy disappeared after successful achievement of remission, and new clones developed in 12 patients during relapse. Two of the four patients originally thought to have a Ph1 chromosome, on trypsin Giemsa handing were proved to have a 21q- chromosome. A higher incidence of aneuploidy was noted in patients under one year or more than 20 years of age and was also higher in patients with low or elevated WBCs at diagnosis. The appearance of aneuploid cells in the bone marrow at the onset or later in the disease is of no prognostic significance but persistence of these lines and the development of total aneuploidy signals a poor prognosis. Eradication of aneuploid cells is therefore essential for the achievement of a long remission and progress to a permanent cure.