Aldehyde dehydrogenase activity in leukemic blasts defines a subgroup of acute myeloid leukemia with adverse prognosis and superior NOD/SCID engrafting potential.

Aldehyde dehydrogenase (ALDH) activity is used to define normal hematopoietic stem cell (HSC), but its link to leukemic stem cells (LSC) in acute myeloid leukemia (AML) is currently unknown. We hypothesize that ALDH activity in AML might be correlated with the presence of LSC. Fifty-eight bone marrow (BM) samples were collected from AML (n=43), acute lymphoblastic leukemia (ALL) (n=8) and normal cases (n=7). In 14 AML cases, a high SSC(lo)ALDH(br) cell population was identified (ALDH(+)AML) (median: 14.89%, range: 5.65-48.01%), with the majority of the SSC(lo)ALDH(br) cells coexpressing CD34(+). In another 29 cases, there was undetectable (n=23) or rare (< or =5%) (n=6) SSC(lo)ALDH(br) population (ALDH(-)AML). Among other clinicopathologic variables, ALDH(+)AML was significantly associated with adverse cytogenetic abnormalities. CD34(+) BM cells from ALDH(+)AML engrafted significantly better in NOD/SCID mice (ALDH(+)AML: injected bone 21.11+/-9.07%; uninjected bone 1.52+/-0.75% vs ALDH(-)AML: injected bone 1.77+/-1.66% (P=0.05); uninjected bone 0.23+/-0.23% (P=0.03)) with the engrafting cells showing molecular and cytogenetic aberrations identical to the original clones. Normal BM contained a small SSC(lo)ALDH(br) population (median: 2.92%, range: 0.92-5.79%), but none of the ALL cases showed this fraction. In conclusion, SSC(lo)ALDH(br) cells in ALDH(+)AML might denote primitive LSC and confer an inferior prognosis in patients.

Doping control analysis of 121 prohibited substances in equine hair by liquid chromatography-tandem mass spectrometry.

Equine hair is becoming an increasingly popular biological matrix for doping control of horse sports; one of the reasons for this is the significantly longer detection window hair can offer. Hair analysis opens up the opportunity for longitudinal monitoring of drug exposure which would otherwise not be possible with the more traditional and common biological matrices, such as urine and blood. As such, there is a need for more multi-target screening methods covering a broad range of prohibited substances in equine hair at the required sensitivities for equine doping control. This paper describes a sensitive ultra-high performance liquid chromatography - tandem mass spectrometry (UHPLC-MS/MS) method for the detection of 121 drugs and/or their metabolites in equine hair covering ten classes of prohibited substances with estimated limits of detection between 0.1 and 10 pg/mg. To our knowledge, this is the first report of a screening method in equine hair which can cover such a broad range and well over one hundred prohibited substances in a single analytical run. This method has been validated for its specificity, precision and extraction recovery. Applicability of this method has been demonstrated by: (i) the successful identification of clenbuterol, 2-(1-hydroxyethyl) promazine sulfoxide, acepromazine and tetrahydrozoline in genuine equine mane samples; as well as (ii) the detection of drugs from artificially incurred mane hair samples which have been prepared by soaking blank hair samples in solutions of drug targets.

Characterization of additional genetic events in childhood acute lymphoblastic leukemia with TEL/AML1 gene fusion: a molecular cytogenetics study.

TEL/AML1 gene fusion that results from a cryptic t(12;21) is the most common genetic aberration in childhood B-lineage acute lymphoblastic leukemia (ALL). While the translocation may initiate the leukemic process, critical secondary genetic events are currently believed to be pivotal for leukemogenesis. We investigated 12 cases of childhood ALL with TEL/AML1 gene fusion by fluorescence in situ hybridization (FISH) and comparative genomic hybridization (CGH) and documented additional or secondary genetic changes in seven patients (58%). Three patients showed extra copies of chromosome 21 including a case in which the trisomy 21 (+21) clone was distinct from the one harboring TEL/AML1 gene fusion. Interestingly, one patient without +21 showed amplification of the AML1 gene on chromosome 21q, supporting the contention that AML1 amplification may be an important additional genetic event. Gene expression study by semi-quantitative reverse-transcription polymerase chain reaction (RT-PCR) in two of these four patients showed an increase in AML1 transcripts that paralleled the increase in gene copy number. Deletion of the normal TEL allele was detected in two patients, with one of them showing loss of chromosome 12 together with duplication of the der(12)t(12;21). Finally, one patient showed duplication of the fusion signal. Our findings confirm that additional or secondary genetic changes including AML1 amplification are commonly encountered in childhood ALL with TEL/AML1 gene fusion, which are envisaged to play significant roles in disease progression.

Prokineticin signaling is required for the maintenance of a de novo population of c-KIT⁺ cells to sustain neuroblastoma progression.

High cellular heterogeneity within neuroblastomas (NBs) may account for the non-uniform response to treatment. c-KIT(+) cells are frequently detected in NB, but how they influence NB behavior still remains elusive. Here, we used NB tumor-initiating cells to reconstitute NB development and demonstrated that c-KIT(+) cells are de novo generated and dynamically maintained within the tumors to sustain tumor progression. c-KIT(+) NB cells express higher levels of neural crest and stem cell markers (SLUG, SOX2 and NANOG) and are endowed with high clonogenic capacity, differentiation plasticity and are refractory to drugs. With serial transplantation assays, we found that c-KIT expression is not required for tumor formation, but c-KIT(+) cells are more aggressive and can induce tumors ninefold more efficiently than c-KIT(-/low) cells. Intriguingly, c-KIT(+) cells exhibited a long-term in vivo self-renewal capacity to sustain the formation of secondary and tertiary tumors in mice. In addition, we showed that Prokineticin signaling and mitogen-activated protein kinase pathways are crucial for the maintenance of c-KIT(+) cells in tumor to promote NB progression. Our results highlight the importance of this de novo population of NB cells in sustainable growth of NB and reveal specific signaling pathways that may provide targets leading to more effective NB therapies.

Trisomy 5 in two cases of acute monocytic leukemia with hyperdiploid clones.

Although numerical chromosomal aberrations are commonly seen in acute myeloid leukemia (AML), trisomy 5 (+ 5) is very rarely detected. We report two patients, both of whom suffered from acute monocytic leukemia, in which + 5 was found in hyperdiploid clones. A review of the English literature shows 17 additional cases of AML with + 5 in at least one of the abnormal clones, making a total of 19 such cases including ours. Trisomy 5 has been reported in all FAB subtypes of AML except acute promyelocytic leukemia. In the 19 cases identified in this report, + 5 was found in association with other numerical changes (four cases), structural changes (five cases) or both (eight cases). Trisomy 5 as a sole karyotypic abnormality was exceedingly rare (two cases). Its biologic and prognostic significance remains to be determined.

Trisomy 21 as the sole acquired karyotypic abnormality in acute myeloid leukemia and myelodysplastic syndrome.

We report five cases of myeloid disorders in which trisomy 21 (+21) was found as the sole acquired karyotypic abnormality, comprising two cases of acute myeloid leukemia (AML) and three cases of myelodysplastic syndrome (MDS). In this series, MDS patients with +21 presented as high grade disease, which included two cases of refractory anemia with excess of blasts (RAEB) and one case of refractory anemia with excess of blasts in transformation (RAEBt), and showed rapid disease progression. Significant thrombocytopenia was observed in all three patients, and bone marrow examination showed a marked reduction in megakaryocytes. AML patients with +21 included one case each of AML-M2 and M4. Despite the poor prognosis reported in AML patients with +21 as the sole abnormality, the patient in our series who was able to complete intensive treatment was cured of disease. The role of +21 in leukemogenesis is reviewed.

Pathogenesis of jumping translocations: a molecular cytogenetics study.

BACKGROUND/AIMS: Jumping translocations are rare cytogenetic aberrations in haematological malignancies, the pathogenesis of which remains to be fully characterised. We investigated the mechanism of formation of jumping translocations in a case of adult common acute lymphoblastic leukaemia (ALL) positive for the Ph translocation. METHODS: Interphase and metaphase fluorescence in situ hybridisation (FISH) was performed using several probe systems. Results were correlated with findings on conventional cytogenetics. Granulocytes, T-cells and leukaemic B-cells in peripheral blood were sorted by immunomagnetic method and the terminal restriction fragment (TRF) length of these cellular populations was determined by Southern blot analysis. RESULTS: Duplicated BCR-ABL fusion signals were found on a dic(14;22)der(22)t(9;22) chromosome. Clonal jumping translocations, existing as evolutionary changes, involved the donor chromosomal segment distal to 1q12 jumping onto the telomere ends of 11q, 15p, 19p and 20p. Telomere length was decreased in the neoplastic B-cell population and contributed to the formation of the dicentric chromosome that showed absence of telomere repeats at fusion ends. Subsequent pericentromeric heterochromatin decondensation of chromosome 1q occurred, and this donor segment was randomly fused to the shortened telomere ends of non-homologous chromosomes. CONCLUSIONS: Both telomere shortening and pericentromeric heterochromatin decondensation contribute to the formation of jumping translocations, which is most probably a multi-stage process.

Expression profile of senescence-associated beta-galactosidase and activation of telomerase in human ovarian surface epithelial cells undergoing immortalization.

Senescence is a specific physiological stage of cells characterized by long population doubling time. It accounts for the inability of normal somatic cells to undergo indefinite cell division. As the number of population doublings increase, cell cycle regulatory mechanisms come into play and signal cells to exit the cell cycle and become senescent. Senescence has been implicated in the aging process and may function as a tumor suppressor mechanism in human cells. The ability to measure the degree of cellular senescence is important in understanding the biological processes regulating cell aging and immortalization. Senescent cells exhibit an enzyme termed senescence-associated histochemical staining. Cells immortalized by viral oncogenes often enter a stage of crisis at the early phase of immortalization. The cells at crisis have a long population doubling time. Cells at the crisis stage resemble senescent cells and the expression of SA- beta-Gal may be used to monitor the process of immortalization. In this study the expression profile of SA-beta-Gal was examined in human ovarian surface epithelial cells (HOSE 6-3) undergoing immortalization by the human papilloma viral oncogene E6 and E7 (HPV E6 and E7). Our results showed a low percentage (12.0%) of HOSE 6-3 cells expressing SA-beta-Gal activity at the pre-crisis stage. The percentage of HOSE 6-3 cells expressing SA-beta-Gal activity was highest (39.2%) at the crisis stage. When HOSE 6-3 cells achieved immortalized status there was a sharp decrease in cells (1. 3%) expressing SA-beta-Gal activity. In addition, an inverse relationship between the expression of SA-beta-Gal activity and telomerase activity was noted in cells undergoing immortalization. The results confirm that the SA-beta-Gal enzyme is a good marker for monitoring the population of cells undergoing senescence at different stages of immortalization and that telomerase activation is a characteristic feature of post-crisis cells.

Presence of human papillomavirus in esophageal squamous cell carcinomas of Hong Kong Chinese and its relationship with p53 gene mutation.

There is no scientific study that has investigated the association between human papilloma virus (HPV) and p53 mutation in Hong Kong Chinese patients with esophageal cancers. The aim of this survey is to evaluate in details the prevalence and relationship of HPV and p53 mutation in these patients with esophageal squamous cell carcinomas. Fresh tissues from the resected specimens of 70 Chinese patients (59 men, 11 women) with primary esophageal squamous cell carcinomas (20 well-differentiated, 36 moderately differentiated, and 14 poorly differentiated squamous cell carcinomas) were tested for the presence of HPV and p53 mutation using the polymerase chain reaction (PCR), single-strand conformational polymorphism (SSCP) analysis, and DNA sequencing. No HPV type 18 was detected, whereas HPV type 16 was identified in 8.6% (6 of 75) of the cases. p53 mutation was found in 44% (31 of 70) of the tumors. The mean ages of HPV-positive and HPV-negative groups of patients were 55 and 64 years, respectively (P = .046, t-test). There was no correlation between the prevalence of HPV and p53 mutation in these tumors. The presence of HPV and p53 also had no relation to the sex of the patients or to the grade of the carcinomas. It is concluded that the overall low prevalence of HPV in esophageal carcinomas may suggest that the virus may not play an important role in the pathogenesis of these tumors in Hong Kong Chinese patients. Also, p53 mutation and integrated HPV DNA are not mutually exclusive in esophageal cancer.

Transformation of diffuse large B-cell lymphoma into pre-B acute lymphoblastic leukemia: clinicopathologic features and clonal relationship.

A patient with fibrosing alveolitis developed a diffuse large B-cell (DLBC) lymphoma that expressed CD20 and CD30. After an initial response, the lymphoma relapsed and was salvaged with further chemotherapy. After another remission of 3 years, a pre-B-cell acute lymphoblastic leukemia (ALL), which expressed CD10, CD19, CD22, CD79a, CD34 and terminal deoxyribonucleotidyl transferase, developed and led to death. Molecular analysis of the immunoglobulin heavy-chain gene showed that the initial lymphoma and its relapse were clonally related. At leukemic relapse, 2 clones related to the initial and relapsed lymphoma clones were present. DLBC lymphomas arise from post-follicle center B cells, whereas ALL arises from pregerminal B cells. Therefore, a direct transformation of DLBC lymphoma to ALL appears unlikely. The overall features suggest instead separate lymphoma and leukemic evolution from a common mutated B-cell precursor rather than transformation of DLBC lymphoma to ALL.

The role of trisomy 8 in the pathogenesis of chronic eosinophilic leukemia.

A case of chronic eosinophilic leukemia (CEL) manifesting as spinal cord compression by an extradural eosinophilic chloroma in a 32-year-old Chinese man was presented, who subsequently developed extramedullary transformation at the skin and then peritoneal cavity. Cytogenetic study of bone marrow cells at diagnosis showed a clonal karyotypic abnormality of trisomy 8 (+8), which on fluorescence in situ hybridization (FISH) was shown to be present in a clone of abnormal eosinophils, hence showing the neoplastic nature of the eosinophilic proliferation. There was another population of abnormal eosinophils that did not show +8. At blastic transformation, all blast cells in ascitic fluid were shown by FISH to harbor +8. These findings suggest that +8 in this case may have arisen from clonal evolution and is not the primary genetic event in leukemogenesis, but +8 most probably imparts a further survival advantage to the clone responsible for subsequent blastic transformation.

Late onset post-transplantation lymphoproliferative disease of recipient origin following cytogenetic relapse and occult autologous haematopoietic regeneration after allogeneic bone marrow transplantation for acute myeloid leukaemia.

A post-transplantation lymphoproliferative disease (PTLD) of recipient origin was identified in one of 376 consecutive cases of allogeneic bone marrow transplantation (BMT). This occurred in a 36-year-old woman who received an allogeneic BMT for acute myeloid leukaemia in relapse. At 15 months after BMT, recipient haematopietic and leukaemic cells were found in the bone marrow, which disappeared on withdrawal of immunosuppression. However, severe graft-versus-host disease (GVHD) necessitated the continuation of immunosuppression, leading to the occurrence of PTLD in the liver and lung 12 months afterwards. Fluorescence in situ hybridisation showed that the neoplastic cells were of recipient origin. Although the PTLD also responded completely to withdrawal of immunosuppression, the patient finally died from the complications of GVHD. This case of late onset PTLD post-BMT showed features similar to those in solid organ transplantation, in that the tumour was of recipient origin and responded well to the withdrawal of immunosuppression. Of further interest is that recipient lymphoid regeneration had accompanied autologous haematopoietic regeneration and become a target for subsequent neoplastic transformation.

Tyrosine kinase inhibitor STI571 in the treatment of Philadelphia chromosome-positive leukaemia failing myeloablative stem cell transplantation.

Eight patients with Philadelphia chromosome-positive (Ph(+)) leukaemia relapsing from stem cell transplantation (SCT) (one syngeneic and seven allogeneic) were treated with the tyrosine kinase inhibitor STI571. Five patients relapsing as chronic myeloid leukaemia (CML) in chronic phase achieved a complete haematological response, with complete and major cytogenetic responses occurring in four and one cases, respectively. One patient became negative for BCR/ABL in the bone marrow. Three patients relapsed as acute leukaemia (two CML in myeloblastic crisis and one Ph(+) acute lymphoblastic leukaemia), all of whom achieved haematological and cytogenetic responses. One patient also became BCR/ABL negative. However, pancytopenia and graft-versus-host disease led to cessation of treatment in the remaining two cases, which was followed by disease recurrence refractory to further STI treatment. Our results showed that Ph(+) leukaemic relapses after SCT might respond well to STI571 therapy.

Derivative chromosome 9 deletions in chronic myeloid leukaemia: interpretation of atypical D-FISH pattern.

BACKGROUND/AIMS: New molecular cytogenetic techniques are increasingly applied as a routine investigative tool in haematological malignancies, both at diagnosis and subsequent monitoring. This report describes the interpretation of atypical signal patterns encountered using BCR-ABL dual colour dual fusion fluorescence in situ hybridisation (D-FISH) translocation probes in chronic myeloid leukaemia (CML). METHODS: Interphase FISH experiments were carried out using BCR-ABL D-FISH probes in 46 patients with CML at diagnosis and during subsequent disease monitoring. Atypical hybridisation signal patterns were characterised by molecular cytogenetic techniques and correlated with conventional karyotyping. RESULTS: Two patients showed atypical interphase D-FISH patterns with one orange, one green, and one fusion (1O1G1F) signal. The presence of BCR-ABL gene fusion was documented by a dual colour single fusion (S-FISH) probe. The submicroscopic deletion of the ABL-BCR fusion gene on the derivative chromosome 9 in these cases was subsequently characterised by metaphase FISH on relocated G banded metaphases. CONCLUSIONS: Atypical interphase D-FISH patterns should not be interpreted in isolation and should be considered in conjunction with other cytogenetic or molecular genetic investigations.

Derivative (1;18)(q10;q10): a recurrent and novel unbalanced translocation involving 1q in myeloid disorders.

We report two cases of hematological malignancies, comprising a case of myelodysplastic syndrome (MDS) that rapidly evolved into acute myeloid leukemia, and a case of myeloproliferative disorder (MPD), in which der(1;18)(q10;q10) was found as the sole acquired karyotypic abnormality. This observation indicates that the unbalanced translocation is a recurrent aberration in myeloid disorders. To the best of our knowledge, centromeric fusion between long arms of chromosomes 1 and 18, leading to a normal chromosome 18 substituted with a der(1;18) chromosome, is novel and has not been described in cancer. Mechanistically, either trisomy 1q or monosomy 18p that results from the translocation may potentially contribute to leukemogenesis. Finally, chromosomes with large constitutive heterochromatin bands such as chromosome 1 may be at risk of centromeric instability and be predisposed to centromeric fusion with other chromosomes.

Molecular characterization of der(15)t(11;15) as a secondary cytogenetic abnormality in acute promyelocytic leukemia with cryptic PML-RAR alpha fusion on 17q.

A case of acute promyelocytic leukemia (APL) with cryptic PML-RAR alpha fusion on 17q and add(15p) as a secondary abnormality was characterized using molecular cytogenetic techniques. Spectral karyotyping (SKY) showed that chromosome 11 material was added to 15p, forming a der(15)t(11;15), which was refined to der(15)t(11;15)(q13.2;p13) with information obtained by comparative genomic hybridization (CGH). Interstitial insertion of chromosome 15 material into chromosome 17q was found by fluorescence in situ hybridization (FISH) with whole chromosome painting (WCP) probes. This study illustrates the necessity of a combination of molecular cytogenetics to decipher complex karyotypic abnormalities and cryptic translocations in leukemia.

t(High) frequency of telomeric associations in human ovarian surface epithelial cells transformed by human papilloma viral oncogenes.

Viral oncogenes are commonly used to transform and extend the in vitro life span of human epithelial cells. We have established 7 cell lines of human ovarian surface epithelial cells using human papilloma viral oncogenes (HPV-E6E7 ORFs). Cytogenetic analysis of the cell lines revealed a high frequency of telomeric associations ranging from 30% to 100% of the metaphases examined. The short arms of chromosomes 16, 19, 21, and 22 showed a higher rate of telomeric association. Telomeric association with other chromosomal ends appears to be random. Fusion of 2 chromosomes ends may contribute to the genomic instability of transformed cells and lead to further genetic alterations involved in malignant transformation such as gene amplication and loss of heterozygosity. This is the first report describing a high frequency of telomeric associations in human ovarian epithelial cells transformed by HPV oncogenes.

Two balanced and novel chromosomal translocations in myeloid malignancies. characterization by multiplex fluorescence in situ hybridization.

We describe two novel chromosomal translocations in two cases of leukemia in which these translocations were further characterized as the sole acquired karyotypic abnormality by mutliplex fluorescence in situ hybridization (M-FISH). They comprised a case of acute myeloid leukemia with t(6;10)(q21;p12) and a case of chronic myelomonocytic leukemia with t(5;12)(q34;q24). To the best of our knowledge, these two balanced translocations are novel and are hitherto unrecognized in hematologic malignancies. While the clinical and pathogenic significance of these translocations remains to be defined, the present report illustrates that M-FISH technology contributes to the exclusion of subtle or cryptic translocations in sole karyotypic aberrations and the confirmation of novel chromosomal arrangements in neoplastic disorders.

Complex variant 15;17 translocations in acute promyelocytic leukemia. A case report and review of three-way translocations.

Complex variant 15;17 translocations are increasingly recognized in acute promyelocytic leukemia (APL). We report a novel three-way translocation in APL involving chromosomes 15, 17, and X in the form of t(X;17;15)(q13;q12;q21). Southern blot analysis showed retinoic acid receptor alpha (RARA) gene rearrangement at intron 2. Clinical and morphologic findings are typical of APL, and a complete remission was attained with a course of conventional chemotherapy. A review of three-way complex variants of 15;17 translocation in the literature reveals 21 published cases in addition to ours. PML/RARA fusion was observed in all 8 cases in which molecular genetic analysis had been performed. More cases need to be analyzed to determine if clustering to particular chromosomal bands occurs in variant translocations, and whether APL cases harboring complex 15;17 variants differ clinically from those with classical 15;17 translocation.

Atypical chronic myeloid leukemia with der(20)t(17;20)(q21;q13).

We present a case of atypical chronic myeloid leukemia that developed blastic transformation four months after initial presentation, with the blast cells showing multilineage antigen expression. A novel karyotypic abnormality, der(20)t(17;20)(q21;q13), was found in bone marrow cells at diagnosis. The potential role of such an aberration in leukemogenesis is discussed.