Role of heterochromatin during preferential 9q;22q translocation in chronic myelogenous leukemia

The secondary constriction region (h) of human chromosome 9 was evaluated in 55 chronic myelogenous leukemia (CML) patients with respect to its size and position. Each case was examined by C-banding and distamycin A-4,6-diamidino-2-phenylindole techniques for the expression of the h regions. When one h region of chromosome 9 was larger, it was more frequently involved in the reciprocal translocation with chromosome 22. In addition, there was a higher incidence of pericentric inversions in the h regions in the translocated chromosome 9 when compared with normal homologues. The role of the constitutive heterochromatin of chromosome 9 as a possible influencing factor during 9q;22q translocation in CML is suggested.     

Characterization of a complex philadelphia translocation (1p-;9q+;22q-) by gene mapping

Summary Human-Chinese hamster somatic cell hybrids were obtained using circulating leucocytes from a chronic myeloid leukaemia (CML) patient carrying a complex Philadelphia (Ph¹) translocation (1p-; 9q+; 22q-). Hybrid clones which showed segregation of the translocation chromosomes were studied. The chromosome 22 markers ACO2, ARSA, and NAGA segregated with the 1p- derivative; and the chromosome 1 markers UMPK, PGD, and ENO1 segregated with the 9q+ derivative. Hence, molecular evidence has been obtained for the translocation of the distal part of 22q to chromosome 1 and for the translocation of the distal part of 1p to chromosome 9. No conclusions could be drawn either about translocation of chromosome 9 material or about a possible difference in breakpoint in chromosome 22 when compared with six cases of 9;22 translocations similarly studied and previously reported. In addition, a more precise mapping of PGM1 was obtained, the gene being proximal to UMPK and the breakpoint in 1p32.     

Interferon alfa-2c in chronic myelogenous leukemia (CML): hematologic, cytogenetic and molecular-genetic response of patients with chronic phase CML previously resistant to therapy with interferon gamma

Alpha- and gamma-interferons have been shown to actively suppress hematopoiesis in patients in the chronic phase of chronic myelogenous leukemia in vitro and in vivo. Since both interferons act through different receptors on their hematopoietic target cells, they are expected to be capable of independently inhibiting abnormal blood cell development in patients with chronic myelogenous leukemia. We have utilized recombinant human interferon alfa-2c to treat 11 patients with Philadelphia chromosome positive chronic myelogenous leukemia in chronic phase, who were resistant to previous interferon gamma therapy. Ten of the patients were evaluable for hematologic, cytogenetic and molecular-genetic response following interferon alfa-2c therapy for 6 to 30 months. In 5 patients, IFN alfa-2c treatment failed due to lack of hematologic response. A complete hematologic or partial hematologic response was achieved in the remaining 5 patients. Three of these experienced cytogenetic improvement with reappearence of 100% diploid hematopoietic cells and disappearence of c-abl/bcr rearrangement in one patient. In two patients interferon alfa-2c did not prevent transformation of the disease into an accelerated state or blast crisis, respectively. We conclude that recombinant human interferon alfa-2c may also control hematopoiesis in interferon-gamma resistant chronic myelogenous leukemia patients, although the long-term response will need to be elucidated in further studies.     

Molecular cytogenetic characterization of 17 rob(13q14q) Robertsonian translocations by FISH, narrowing the region containing the breakpoints.

We have characterized 17 rob(13q14q) Robertsonian translocations, using six molecular probes that hybridize to the repetitive sequences of the centromeric and shortarm regions of the five acrocentric chromosomes by FISH. The rearrangements include six de novo rearrangements and the chromosomally normal parents, five maternally and three paternally inherited translocations, and three translocations of unknown origin. The D21Z1/D13Z1 and D14Z1/D22Z1 centromeric alpha-satellite DNA probes showed all rob(13q14q) chromosomes to be dicentric. The rDNA probes did not show hybridization on any of the 17 cases studied. The pTRS-47 satellite III DNA probe specific for chromosomes 14 and 22 was retained around the breakpoints in all cases. However, the pTRS-63 satellite III DNA probe specific for chromosome 14 did not show any signals on the translocation chromosomes examined. In 16 of 17 translocations studied, strong hybridization signals on the translocations were detected with the pTRI-6 satellite I DNA probe specific for chromosome 13. All parents of the six de novo rob(13q14q), including one whose pTRI-6 sequence was lost, showed strong positive hybridization signals on each pair of chromosomes 14 and 13, with pTRS-47, pTRS-63, and pTRI-6. Therefore, the translocation breakpoints in the majority of rob(13q14q) are between the pTRS-47 and pTRS-63 sequences in the p11 region of chromosome 14 and between the pTRI-6 and rDNA sequences within the p11 region of chromosome 13.     

Sperm chromosome analysis of two men heterozygous for reciprocal translocations: t(1;9)(q22;q31) and t(16;19)(q11.1;q13.3).

Sperm chromosome complements were analysed in two men who were heterozygous carriers of reciprocal translocations. A total of 363 sperm were karyotyped after in vitro penetration of hamster oocytes, including 180 sperm from a male with a t(1;9)(q22;q31) and 183 from a male with a t(16;19)(q11.1;q13.3). All possible 2:2 and 3:1 meiotic segregations were observed for both translocations. The frequencies of alternate, adjacent 1, adjacent 2, and 3:1 segregations were 46%, 38%, 13%, and 4% for the t(1;9) and 40%, 28%, 31%, and 1% for the t(16;19), respectively. Within the alternate segregation group, the number of normal sperm was not significantly different from the number of sperm carrying a balanced form of the translocation for either of the translocations, as expected. There was no evidence for an interchromosomal effect of either translocation, since the frequencies of numerical abnormalities unrelated to the translocation were within the normal range observed in sperm from control donors. The percentage of sperm with an unbalanced form of the translocation was 54% for the t(1;9) and 61% for the t(16;19).     

Pachytene analysis in males heterozygous for a familial translocation (9;12;13) (q22; q22; q32) ascertained through a child with partial trisomy 9

A family with four male and three female heterozygotes for a three-way translocation (9;12;13) (q22; q22; q32) in three generations was ascertained through a chromosomally imbalanced newborn with an additional derivative chromosome 9 resulting from nondisjunction. Three heterozygous males from two generations with apparent differences in their fertility status were investigated using pachytene spreads and testicular histology. Pachytene analysis in all three individuals, the fertile (II-2) as well as the subfertile (III-7) and infertile (III-9), showed a hexavalent with central nonpairing around the translocation breakpoints in nearly all spermatocytes. Thus, the observed hexavalent configurations in pachytene do not seem to have caused impaired fertility. This rather may have been the result of sperm carrying unbalanced chromosome sets. However, the observed difference in fertility between the heterozygous fertile male in generation II and his two heterozygous sons remains unexplained.     

An infant with trisomy 9pter yields 9q22 resulting from 3:1 segregation in a 46,XX t(1;9) (p36;q22) mother.

A newborn infant with a 47,XY,+ der(.),t(1;9) (p36;q22)mat chromosome complement and the clinical features of the 9p trisomy is described. A review of the reproductive histories of five cases with trisomy 9pter yields 9q21 or 22 indicate that the balanced translocation mothers of these infants may have as high as a 23% chance of producing a chromosomally unbalanced offspring due to 3:1 disjunction.     

A novel translocation,t(9;21)(q13;q22) rearranging the RUNX1 gene in acute myelomonocytic leukemia

A novel translocation t(9;21)(q13;q22) associated with trisomy 4 has been detected in a patient with acute myelomonocytic leukemia (AML,M4) in relapse. The chromosomal translocation results in rearrangement of the RUNX1 gene at 21q22. The DNA sequence rearranged on chromosome 9 remains unidentified. The diversity of the partners involved in translocations implicating RUNX1 suggests that the functional consequences of the abnormality are more due to the truncation of RUNX1 than to the identity of its partner in the rearrangement.     

A Case of ABL-BCR Negative, Philadelphia Positive CML with t(5;9)(q13;q34)

The Philadelphia chromosome is found in more than 90 percent of chronic myeloid leukemia (CML) patients. In most cases, it results from the reciprocal t(9;22)(q34;q11), with the ABL proto-oncogene from 9q34 fused to the breakpoint cluster region (BCR) locus on 22q11. In 5 to 10 percent of patients with CML, the Ph originates from variant translocations, involving various breakpoints in addition to 9q34 and 22q11. Here we report a rare case of a Philadelphia positive CML patient carrying t(5;9)(q13;q34) and deletion of ABL/BCR on der(9) as a separate event.     

Translocation (3;21)(q26;q22) in secondary leukemia. Report of two cases and literature review.

The authors report two cases of secondary myelodysplasia and acute myeloid leukemia with t(3;21)(q26.3;q22) as the only cytogenetic abnormality in neoplastic bone marrow. This translocation was identified as a rare, recurring, non-random aberration in chronic myeloid leukemia less than five years ago and in secondary acute myeloid leukemia and myelodysplasia in 1990. The known and suspected cases in the literature are reviewed.     

Human AQP5 plays a role in the progression of chronic myelogenous leukemia (CML)

Aquaporins (AQPs) have previously been associated with increased expression in solid tumors. However, its expression in hematologic malignancies including CML has not been described yet. Here, we report the expression of AQP5 in CML cells by RT-PCR and immunohistochemistry. While normal bone marrow biopsy samples (n = 5) showed no expression of AQP5, 32% of CML patient samples (n = 41) demonstrated AQP5 expression. In addition, AQP5 expression level increased with the emergence of imatinib mesylate resistance in paired samples (p = 0.047). We have found that the overexpression of AQP5 in K562 cells resulted in increased cell proliferation. In addition, small interfering RNA (siRNA) targeting AQP5 reduced the cell proliferation rate in both K562 and LAMA84 CML cells. Moreover, by immunoblotting and flow cytometry, we show that phosphorylation of BCR-ABL1 is increased in AQP5-overexpressing CML cells and decreased in AQP5 siRNA-treated CML cells. Interestingly, caspase9 activity increased in AQP5 siRNA-treated cells. Finally, FISH showed no evidence of AQP5 gene amplification in CML from bone marrow. In summary, we report for the first time that AQP5 is overexpressed in CML cells and plays a role in promoting cell proliferation and inhibiting apoptosis. Furthermore, our findings may provide the basis for a novel CML therapy targeting AQP5.     

Novel variant Ph translocation t(9;22;11)(q34;q11.2;p15)inv(9)(p13q34) in chronic myeloid leukemia involving a one-step mechanism

Chronic myeloid leukemia (CML) is a clonal malignant disorder of a pluripotent hematopoietic stem cell characterized by the presence of a Philadelphia (Ph) chromosome. Less than 10% of patients present variant Ph chromosomes involving 1 or more additional chromosomes, other than chromosomes 9 and 22, with uncertain prognosis. There are mainly 1- or 2-step mechanisms proposed to explain the genesis of variant Ph chromosomes depending on whether the involved chromosomes are simultaneously broken and rejoined or if a standard t(9;22) occurs first. By combined standard cytogenetic and FISH analysis we detected a novel variant Ph translocation among chromosomes 9, 11 and 22 in a patient with CML without progression to an accelerated phase of the disease after 7 years, with the derivative chromosome 9 also having an acquired pericentric inversion. This novel case illustrates the use of FISH in metaphase to confirm a new rearrangement not previously described in variant Ph formation and that the present karyotype could have originated by a 1-step mechanism with 4 simultaneous breakages without deletion of ABL1.     

Complex translocation t(9;21)(9;22)(q12p13)(q12q11) in the family of a child with 9p trisomy syndrome

Summary Leukocyte peroxidase activity was estimated in 5 patients with the juvenile form of neuronal ceroid lipofuscinosis (Spielmeyer-Vogt's disease) and in 15 healthy controls. In contradiction to recent reports normal activity of p-phenylene diamine mediated peroxidase was found in the patients. The possible role of contamination of the white cell preparation with hemoglobin is discussed.     

Bone marrow histopathology in chronic myelogenous leukemia (CML)--evaluation of distinctive features with clinical impact.

Bone marrow features in stable-phase chronic myelogenous leukemia (CML) are characterized by a striking heterogeneity which is determinable by appropriate means including representative pre-treatment trephine biopsies, immunohistochemistry and morphometry. Cell lineages involved to a variable extent consist not only of neutrophil granulopoiesis, but include also megakaryocytes, erythroid precursors, resident macrophages and lymphocytes. Moreover, the stromal compartment, in particular reticulin and collagen fibers, plays a pivotal role in the disease process. Following morphometric analysis significant correlations may be calculated between histological parameters and clinical-laboratory findings. Relevant interactions are detectable between number of megakaryocytes and their precursors with fiber density. This findings is in line with the close functional relationships between megakaryopoiesis and fibroblasts regarding the complex pathomechanisms of myelofibrosis. Moreover, other correlations are observable between reduction of erythropoiesis or increase in fibers with clinical features like anemia, percentages of myelo- and erythroblasts in the peripheral blood, spleen size or LDH level. These variables are in keeping with more advanced stages of CML which indicate a transition to myeloid metaplasia and thus exert a significant impact on survival. Consequently, the different risk profiles of patients are determined by both clinical and morphological parameters of predictive value. Regarding the latter, extent of myelofibrosis, amount of erythroid precursors and numbers of myeloerythroblasts in the peripheral blood are significantly associated with prognosis. For this reason, it should be mandatory to enter morphological criteria into prospective clinical trials on CML, not only for diagnostic purpose, but also for a proper evaluation of different survival patterns.