Molecular genetics of acute leukaemia

Composite dietary antioxidant index mediates the effect of epilepsy on psychiatric disorders: results from NHANES 2013-2018

Background

Psychiatric disorders is a major public health problem and epilepsy contributes significantly to depression. We aimed to explore the relationship between dietary patterns and mental illness in patients with epilepsy.

Methods

The data presented here are based on the 2013-2018 National Health and Nutrition Examination Survey (NHANES). In this study, the t-test and chi-square tests or one-way analysis of variance (ANOVA) were employed for the analysis of continuous and categorical variables, respectively. Restricted cubic splines (RCSs) with four knots were employed to investigate the linear relationship and trend between the Composite Dietary Antioxidant Index (CDAI) and epilepsy and psychiatric disorders, respectively. In instances where the linear relationship was not deemed to be applicable, the CDAI was categorized into four groups based on quartiles. A logistic regression analysis was employed to investigate the relationship between epilepsy and mental disorders under four distinct models. A mediation analysis was employed to ascertain whether CDAI acted as a mediator in the relationship between epilepsy and mental disorders.

Results

Patients with epilepsy had a significantly lower CDAI (p < 0.001) and a significantly higher prevalence of psychiatric disorders (p = 0.02) compared with non-epileptic patients. Mediation modeling showed that CDAI mediated between 3.17 and 5.21% of epilepsy-related psychiatric disorders. In stratified analyses, the prevalence of psychiatric disorders was increased in the second quartile subgroup and the third quartile subgroup of the CDAI dietary index in patients with epilepsy compared with non-epileptic patients.

Conclusion

Our findings suggest that patients with epilepsy have a high risk of developing psychiatric disorders and that the Composite Dietary Antioxidant Index (CDAI) plays a key role in mediating the relationship between epilepsy and psychiatric disorders.

Role of cardiolipins, mitochondria, and autophagy in the differentiation process activated by all-trans retinoic acid in acute promyelocytic leukemia

The role played by lipids in the process of granulocytic differentiation activated by all-trans retinoic acid (ATRA) in Acute-Promyelocytic-Leukemia (APL) blasts is unknown. The process of granulocytic differentiation activated by ATRA in APL blasts is recapitulated in the NB4 cell-line, which is characterized by expression of the pathogenic PML-RARα fusion protein. In the present study, we used the NB4 model to define the effects exerted by ATRA on lipid homeostasis. Using a high-throughput lipidomic approach, we demonstrate that exposure of the APL-derived NB4 cell-line to ATRA causes an early reduction in the amounts of cardiolipins, a major lipid component of the mitochondrial membranes. The decrease in the levels of cardiolipins results in a concomitant inhibition of mitochondrial activity. These ATRA-dependent effects are causally involved in the granulocytic maturation process. In fact, the ATRA-induced decrease of cardiolipins and the concomitant dysfunction of mitochondria precede the differentiation of retinoid-sensitive NB4 cells and the two phenomena are not observed in the retinoid-resistant NB4.306 counterparts. In addition, ethanolamine induced rescue of the mitochondrial dysfunction activated by cardiolipin deficiency inhibits ATRA-dependent granulocytic differentiation and induction of the associated autophagic process. The RNA-seq studies performed in parental NB4 cells and a NB4-derived cell population, characterized by silencing of the autophagy mediator, ATG5, provide insights into the mechanisms underlying the differentiating action of ATRA. The results indicate that ATRA causes a significant down-regulation of CRLS1 (Cardiolipin-synthase-1) and LPCAT1 (Lysophosphatidylcholine-Acyltransferase-1) mRNAs which code for two enzymes catalyzing the last steps of cardiolipin synthesis. ATRA-dependent down-regulation of CRLS1 and LPCAT1 mRNAs is functionally relevant, as it is accompanied by a significant decrease in the amounts of the corresponding proteins. Furthermore, the decrease in CRLS1 and LPCAT1 levels requires activation of the autophagic process, as down-regulation of the two proteins is blocked in ATG5-silenced NB4-shATG5 cells.

Platelet-derived growth factor receptors (PDGFRs) fusion genes involvement in hematological malignancies

PURPOSE

To investigate oncogenic platelet-derived growth factor receptor(PDGFR) fusion genes involvement in hematological malignancies, the advances in the PDGFR fusion genes diagnosis and development of PDGFR fusions inhibitors.

METHODS

Literature search was done using terms "PDGFR and Fusion" or "PDGFR and Myeloid neoplasm" or 'PDGFR and Lymphoid neoplasm' or "PDGFR Fusion Diagnosis" or "PDGFR Fusion Targets" in databases including PubMed, ASCO.org, and Medscape.

RESULTS

Out of the 36 fusions detected, ETV6(TEL)-PDGFRB and FIP1L1-PDGFRA fusions were frequently detected, 33 are as a result of chromosomal translocation, FIP1L1-PDGFRA and EBF1-PDGFRB are the result of chromosomal deletion and CDK5RAP2- PDGFRΑ is the result of chromosomal insertion. Seven of the 34 rare fusions have detectable reciprocals.

CONCLUSION

RNA aptamers are promising therapeutic target of PDGFRs and diagnostic tools of PDGFRs fusion genes. Also, PDGFRs have variable prospective therapeutic strategies including small molecules, RNA aptamers, and interference therapeutics as well as development of adaptor protein Lnk mimetic drugs.

MOZ and MOZ-CBP cooperate with NF-kappaB to activate transcription from NF-kappaB-dependent promoters

OBJECTIVE

Monocytic zinc finger (MOZ) maintains hematopoietic stem cells and, upon fusion to the coactivator CREB-binding protein (CBP), induces acute myeloid leukemia (AML). Leukemic stem cells in AML often exhibit excessive signal-dependent activity of the transcription factor nuclear factor (NF)-kappaB. Because aberrant interaction between NF-kappaB and coactivators represents an alternative mechanism for enhancing NF-kappaB activity, we evaluated whether MOZ and MOZ-CBP cooperate with NF-kappaB to activate transcription from NF-kappaB-dependent promoters.

METHODS

The ability of MOZ, MOZ mutants, and MOZ-CBP to enhance expression of NF-kappaB-dependent promoters was tested in reporter studies. The interaction between MOZ and NF-kappaB was evaluated by both coimmunoprecipitation and glutathione S-transferase pulldown assays.

RESULTS

MOZ activates transcription from the NF-kappaB-dependent interleukin-8 promoter; interestingly, this effect is markedly enhanced by CBP. Although MOZ has less potent transcriptional activity than MOZ-CBP, both proteins cooperate with steroid receptor coactivator-1 to activate transcription. MOZ also induces multiple NF-kappaB-dependent viral promoters. Importantly, MOZ associates in a protein complex with the p65 subunit of NF-kappaB and interacts directly with p65 in vitro. Transcriptional activity of MOZ requires its C-terminal domain, which is absent from MOZ-CBP, indicating that the transcriptional activity of MOZ-CBP derives from its CBP sequence.

CONCLUSIONS

MOZ interacts with the p65 subunit of NF-kappaB and enhances expression of NF-kappaB-dependent promoters. The more potent transcriptional activity of MOZ-CBP derives from its CBP sequence. Thus, interaction between NF-kappaB and MOZ-CBP may play an important role in the pathogenesis of certain acute myeloid leukemias.

Novel methodology for the follow-up of acute lymphoblastic leukemia using FTIR microspectroscopy

In this report, we present a novel spectroscopic method of follow-up during chemotherapy treatment for B- and T-cell childhood leukemia patients. We isolated peripheral lymphocytes from blood drawn from patients before and after the chemotherapy and collected Microscopic FTIR (FTIR-MC) spectra of the isolated lymphocytes. Our results showed that nucleic acids content decreased in both types of patients. Changes in phospholipids and proteins level could be observed. The overall effects of drugs administered to the patients can be understood at the molecular level using FTIR-MC and these results are expected to stimulate wider applications of spectroscopy in leukemia research.

Amplification of AML1 in childhood acute lymphoblastic leukemias

Amplification of AML1 has been confirmed by fluorescence in situ hybridization analysis in two cases of childhood acute lymphoblastic leukemia. It remains to be elucidated whether this amplification results in up-regulation of the normal AML1 gene product or a potentially mutant AML1 transcript.

The t(8;21) chromosomal translocation in acute myelogenous leukemia modifies intranuclear targeting of the AML1/CBFalpha2 transcription factor

Targeting of gene regulatory factors to specific intranuclear sites may be critical for the accurate control of gene expression. The acute myelogenous leukemia 8;21 (AML1/ETO) fusion protein is encoded by a rearranged gene created by the ETO chromosomal translocation. This protein lacks the nuclear matrix-targeting signal that directs the AML1 protein to appropriate gene regulatory sites within the nucleus. Here we report that substitution of the chromosome 8-derived ETO protein for the multifunctional C terminus of AML1 precludes targeting of the factor to AML1 subnuclear domains. Instead, the AML1/ETO fusion protein is redirected by the ETO component to alternate nuclear matrix-associated foci. Our results link the ETO chromosomal translocation in AML with modifications in the intranuclear trafficking of the key hematopoietic regulatory factor, AML1. We conclude that misrouting of gene regulatory factors as a consequence of chromosomal translocations is an important characteristic of acute leukemias.

The (4;11)(q21;p15) Translocation Fuses the NUP98 andRAP1GDS1 Genes and Is Recurrent in T-Cell Acute Lymphocytic Leukemia

We determined the breakpoint genes of the translocation t(4;11)(q21;p15) that occurred in a case of adult T-cell acute lymphocytic leukemia (T-ALL). The chromosome 11 breakpoint was mapped to the region between D11S470 and D11S860. The nucleoporin 98 gene (NUP98), which is rearranged in several acute myeloid leukemia translocations, is located within this region. Analysis of somatic cell hybrids segregating the translocation chromosomes showed that the chromosome 11 breakpoint occurs withinNUP98. The fusion partner of NUP98 was identified as theRAP1GDS1 gene using 3′ RACE. RAP1GDS1 codes for smgGDS, a ubiquitously expressed guanine nucleotide exchange factor that stimulates the conversion of the inactive GDP-bound form of several ras family small GTPases to the active GTP-bound form. In theNUP98-RAP1GDS1 fusion transcript (abbreviated asNRG), the 5′ end of the NUP98 gene is joined in frame to the coding region of the RAP1GDS1 gene. This joins the FG repeat-rich region of NUP98 to RAP1GDS1, which largely consists of tandem armadillo repeats. NRG fusion transcripts were detected in the leukemic cells of 2 other adult T-ALL patients. One of these patients had a variant translocation with a more 5′ breakpoint in NUP98. This is the first report of anNUP98 translocation in lymphocytic leukemia and the first time that RAP1GDS1 has been implicated in any human malignancy.

The (4;11)(q21;p15) Translocation Fuses the NUP98 andRAP1GDS1 Genes and Is Recurrent in T-Cell Acute Lymphocytic Leukemia

We determined the breakpoint genes of the translocation t(4;11)(q21;p15) that occurred in a case of adult T-cell acute lymphocytic leukemia (T-ALL). The chromosome 11 breakpoint was mapped to the region between D11S470 and D11S860. The nucleoporin 98 gene (NUP98), which is rearranged in several acute myeloid leukemia translocations, is located within this region. Analysis of somatic cell hybrids segregating the translocation chromosomes showed that the chromosome 11 breakpoint occurs withinNUP98. The fusion partner of NUP98 was identified as theRAP1GDS1 gene using 3′ RACE. RAP1GDS1 codes for smgGDS, a ubiquitously expressed guanine nucleotide exchange factor that stimulates the conversion of the inactive GDP-bound form of several ras family small GTPases to the active GTP-bound form. In theNUP98-RAP1GDS1 fusion transcript (abbreviated asNRG), the 5′ end of the NUP98 gene is joined in frame to the coding region of the RAP1GDS1 gene. This joins the FG repeat-rich region of NUP98 to RAP1GDS1, which largely consists of tandem armadillo repeats. NRG fusion transcripts were detected in the leukemic cells of 2 other adult T-ALL patients. One of these patients had a variant translocation with a more 5′ breakpoint in NUP98. This is the first report of anNUP98 translocation in lymphocytic leukemia and the first time that RAP1GDS1 has been implicated in any human malignancy.

Cytogenetics and molecular genetics of childhood leukemia

Childhood leukemia is the commonest form of childhood cancer and represents clonal proliferation of transformed hemopoietic cells as a result of genetic changes. Molecular characterization of these changes, in particular chromosomal translocations, has yielded a wealth of information on the mechanisms of leukemogenesis. These findings have also allowed the development of sensitive assays for the identification of underlying molecular defects, which is applicable to disease diagnosis and to monitor response to treatment. Genetic alterations in childhood leukemia are powerful prognostic indicators. TEL-AML1 fusion and hyperdiploidy >50 chromosomes are associated with a good prognosis in childhood acute lymphoblastic leukemia, whereas BCR-ABL fusion and MLL rearrangements are associated with a poor prognosis. Hence cytogenetic and molecular genetic classification of childhood leukemia will significantly improve the ability of clinicians to predict therapeutic response and prognosis, which paves the way for risk stratification based on clinical and genetic features. Finally, deciphering of genetic lesions in leukemia has allowed elucidation of the molecular basis of current treatment, as typified by the success of all-trans retinoic treatment in acute promyelocytic leukemia, and has identified targets for novel therapeutic approaches. It is envisaged that efforts in characterization of molecular defects in childhood leukemia will ultimately be translated into better clinical outcome for patients.

Myeloid- and lymphoid-specific breakpoint cluster regions in chromosome band 13q14 in acute leukemia

Abnormalities of chromosome band 13q14 occur in hematologic malignancies of all lineages and at all stages of differentiation. Unlike other chromosomal translocations, which are usually specific for a given lineage, the chromosomal translocation t(12;13)(p12;q14) has been observed in both B-cell and T-cell precursor acute lymphoblastic leukemia (BCP-, TCP-ALL), in differentiated and undifferentiated acute myeloblastic leukemia (AML), and in chronic myeloid leukemia (CML) at progression to blast crisis. The nature of these translocations and their pathologic consequences remain unknown. To begin to define the gene(s) involved on chromosome 13, we have performed fluorescence in situ hybridization (FISH) using a panel of YACs from the region, on a series of 10 cases of acute leukemia with t(12;13)(p12;q14) and 1 case each with "variant" translocations including t(12;13)(q21;q14), t(10;13)(q24;q14) and t(9;13)(p21;q14). In 8/13 cases/cell lines, the 13q14 break fell within a single 1.4 Mb CEPH MegaYAC. This YAC fell immediately telomeric of the forkhead (FKHR) gene, which is disrupted in the t(2;13)(q35;q14) seen in pediatric alveolar rhabdomyosarcoma. Seven of the 8 cases with breaks in this YAC were AML. In 4/13 cases, the 13q14 break fell within a 1.7-Mb YAC located about 3 Mb telomeric of the retinoblastoma (RB1) gene: all 4 cases were ALL. One case of myelodysplastic syndrome exhibited a break within 13q12, adjacent to the BRCA2 gene. These data indicate the presence of myeloid- and lymphoid-specific breakpoint cluster regions within chromosome band 13q14 in acute leukemia.

Immunotherapeutic approaches to sarcoma

In the last decade, the most important factor in the rekindled interest in immune therapy for cancer is the development of new methods to identify tumor antigens that can be recognized by T-cells and other immune effectors. In addition, greater knowledge about tolerance and mechanisms of tumor cell evasion from immune effectors has made the prospect of developing clinically effective immune therapies for cancer seem promising. Research in immune therapies for sarcoma has been limited, mainly because of the previous lack of defined tumor antigens in this disease and the low prevalence of sarcoma in the general population. We will review the fundamental concepts of tumor immunobiology, both cellular and humoral, and highlight the new, powerful methods for identifying novel tumor antigens. Further, we will focus on the unique situation presented by sarcoma as the only solid tumor in which many cytogenetic abnormalities have been characterized which encode for unique, tumor-specific fusion proteins that are ideal targets for immune-based therapy. We will review the specifics of vaccine therapy approach to this disease, with emphasis on strategies to improve the immunogenicity of newly defined tumor antigens in sarcoma.

The t(8;21) fusion protein, AML1/ETO, transforms NIH3T3 cells and activates AP-1

The 8;21 translocation is the most common cytogenetic abnormality in human acute myelogenous leukemia, joining the AML1 gene on chromosome 21, to the ETO gene on chromosome 8, forming the AML1/ETO fusion gene. The AMLI/ETO fusion protein has been shown to function mainly as a transcriptional repressor of AML1 target genes and to block AML1 function in vitro and in vivo. However, AML1/ETO can also activate the BCL-2 promoter and cause enhanced hematopoietic progenitor self-renewal in vitro, suggesting gain-of-functions unique to the fusion protein. We used NIH3T3 cells to determine the transforming capacity of AML1/ETO, and to further characterize its mechanism of action. Expression of AML1/ETO in NIH3T3 cells caused cell-type specific cell death, and cellular transformation, characterized by phenotypic changes, anchorage-independent growth, and tumor formation in nude mice. In contrast, neither expression of AML1A, AML1B or ETO altered the normal growth pattern of the cells. To investigate the mechanism of transformation by AML1/ETO, we analysed the levels of activated, phosphorylated c-Jun (ser63) and other constituents of the AP-1 complex, in the presence of various AML1/ETO related proteins. Expression of AML1/ETO increased the level of c-Jun-P (ser63), and activated AP-1 dependent transcription, which was inhibited by expression of a dominant-negative c-Jun protein. Mutational analysis revealed that the runt homology domain (RHD) and a C-terminal transcriptional repression domain in AML1/ETO are required for transformation, activation of c-Jun and increased AP-1 activity. These results establish the transforming potential of the t(8;21) fusion protein and link this gain-of-function property to modulation of AP-1 activity.

Molecular abnormalities in myeloid leukemias and myelodysplastic syndromes

Analysis of chromosome translocations in human myeloid leukemias and myelodysplastic syndromes has identified a number of genes involved in the pathogenesis of these diseases. Most of the genes identified to date can be grouped into one of three major classes--transcription factors, tyrosine kinases or nuclear pore proteins. Recent insights into the molecular basis of these leukemias is presented using selected examples from these groups.

Molecular genetics and cytogenetics of myeloproliferative disorders

The myeloproliferative disorders are believed to represent clonal malignancies resulting from transformation of a pluripotent stem cell. X-inactivation patterns of peripheral blood cells have been proposed as a useful diagnostic tool but this method is limited by the finding of a clonal X-inactivation pattern in a significant proportion of normal elderly women. There is no pathognomonic chromosomal abnormality associated with the myeloproliferative disorders. However, consistent acquired cytogenetic changes include del(20q), del(13q), trisomy 8 and 9 and duplication of segments of 1q, all of which have been observed at diagnosis or before cytoreductive therapy and therefore represent early lesions which contribute to the pathogenesis of these disorders. Although, the acquired molecular defects underlying most myeloproliferative disorders have not yet been elucidated, translocations associated with the rare 8p11 syndrome have permitted identification of a novel fusion protein. The role of a number of candidate genes in the other myeloproliferative disorders has also been studied, but no mutations have been identified so far. It is likely that a number of genes will be involved, given the varied phenotypes of the diseases. Identification of causal genes will be of considerable interest to both clinicians, who currently lack a specific and sensitive diagnostic test, and scientists interested in fundamental issues of stem cell behaviour.

Fetal origins of the TEL-AML1 fusion gene in identical twins with leukemia

The TEL (ETV6)-AML1 (CBFA2) gene fusion is the most common reciprocal chromosomal rearrangement in childhood cancer occurring in approximately 25% of the most predominant subtype of leukemia- common acute lymphoblastic leukemia. The TEL-AML1 genomic sequence has been characterized in a pair of monozygotic twins diagnosed at ages 3 years, 6 months and 4 years, 10 months with common acute lymphoblastic leukemia. The twin leukemic DNA shared the same unique (or clonotypic) but nonconstitutive TEL-AML1 fusion sequence. The most plausible explanation for this finding is a single cell origin of the TEL-AML fusion in one fetus in utero, probably as a leukemia-initiating mutation, followed by intraplacental metastasis of clonal progeny to the other twin. Clonal identity is further supported by the finding that the leukemic cells in the two twins shared an identical rearranged IGH allele. These data have implications for the etiology and natural history of childhood leukemia.

TEL-AML1 Fusion Transcript in Relapsed Childhood Acute Lymphoblastic Leukemia

The cryptic translocation t(12;21)(p13;q22) has been recently recognized as the most common genetic rearrangement in B-lineage childhood acute lymphoblastic leukemia (ALL). The resulting fusion transcript, termed TEL-AML1, has been associated with an excellent prognosis at initial ALL diagnosis. Hence, we postulated that the incidence of TEL-AML1 fusion should be lower in patients with ALL relapse. To address this assumption and to investigate the prognostic significance of TEL-AML1 expression in relapsed childhood ALL, bone marrow samples of 146 children were analyzed by reverse-transcriptase (RT)-polymerase chain reaction (PCR). All children were treated according to Berlin-Frankfurt-Münster (BFM) ALL relapse trial protocols (ALL-REZ BFM 90-96). Their clinical features and outcome were compared with those of 262 patients who could not be tested due to lack of bone marrow samples. Thirty-two of 146 children with relapsed ALL were TEL-AML1–positive. Four of the negative patients had T-lineage and nine Philadelphia chromosome (Ph1)-positive leukemia. Thus, the incidence ofTEL-AML1 in relapsed Ph1-negative, B-cell precursor ALL is 32 of 133 (24%). The 32 TEL-AML1–positive and 101 negative patients differed significantly with respect to duration of last remission (42.5 v 27 months; P = .0001) and age at initial diagnosis (53.5 v 74 months;P = .0269). At a median follow-up time of 21.5 months, children positive for TEL-AML1 had a significantly (P = .0011) higher probability of event-free survival (EFS; 0.79 v 0.33). The predominant majority of patients had been treated for initial ALL according to German multicenter BFM (108 of 133) or Cooperative ALL study group (CoALL) (19 of 133) frontline protocols. The comparison of tested and not-tested (N = 262) patients showed no significant difference.TEL-AML1 positivity predicted a favorable short-term outcome; long-term results are unknown. Screening for TEL-AML1 should become routine at relapse diagnosis and might be used for therapy stratification in future trials.

TEL-AML1 Fusion Transcript in Relapsed Childhood Acute Lymphoblastic Leukemia

The cryptic translocation t(12;21)(p13;q22) has been recently recognized as the most common genetic rearrangement in B-lineage childhood acute lymphoblastic leukemia (ALL). The resulting fusion transcript, termed TEL-AML1, has been associated with an excellent prognosis at initial ALL diagnosis. Hence, we postulated that the incidence of TEL-AML1 fusion should be lower in patients with ALL relapse. To address this assumption and to investigate the prognostic significance of TEL-AML1 expression in relapsed childhood ALL, bone marrow samples of 146 children were analyzed by reverse-transcriptase (RT)-polymerase chain reaction (PCR). All children were treated according to Berlin-Frankfurt-Münster (BFM) ALL relapse trial protocols (ALL-REZ BFM 90-96). Their clinical features and outcome were compared with those of 262 patients who could not be tested due to lack of bone marrow samples. Thirty-two of 146 children with relapsed ALL were TEL-AML1–positive. Four of the negative patients had T-lineage and nine Philadelphia chromosome (Ph1)-positive leukemia. Thus, the incidence ofTEL-AML1 in relapsed Ph1-negative, B-cell precursor ALL is 32 of 133 (24%). The 32 TEL-AML1–positive and 101 negative patients differed significantly with respect to duration of last remission (42.5 v 27 months; P = .0001) and age at initial diagnosis (53.5 v 74 months;P = .0269). At a median follow-up time of 21.5 months, children positive for TEL-AML1 had a significantly (P = .0011) higher probability of event-free survival (EFS; 0.79 v 0.33). The predominant majority of patients had been treated for initial ALL according to German multicenter BFM (108 of 133) or Cooperative ALL study group (CoALL) (19 of 133) frontline protocols. The comparison of tested and not-tested (N = 262) patients showed no significant difference.TEL-AML1 positivity predicted a favorable short-term outcome; long-term results are unknown. Screening for TEL-AML1 should become routine at relapse diagnosis and might be used for therapy stratification in future trials.

Gene Immunotherapy in Murine Acute Myeloid Leukemia: Granulocyte-Macrophage Colony-Stimulating Factor Tumor Cell Vaccines Elicit More Potent Antitumor Immunity Compared With B7 Family and Other Cytokine Vaccines

In an attempt to explore novel treatment modalities in acute myeloid leukemia (AML), we studied the role of costimulatory and cytokine gene immunotherapy in murine AML. We have previously shown that leukemic mice can be cured with CD80 transfected leukemic cells (B7.1-AML vaccine) administered early in the course of the disease and that the failure B7.1-AML vaccines administered late cannot be attributed to immunosuppression induced by tumor growth. CD8+ T cells, which are necessary for tumor rejection, are activated rather than suppressed during the first half of the leukemic course in nonvaccinated mice. In this report, we question whether CD86 (B7.2) or the cytokines granulocyte-macrophage colony-stimulating factor (GM-CSF), interleukin-4 (IL-4), or tumor necrosis factor-α (TNF-α) can improve the vaccination potential of AML cells. The choice of cytokines was based on their combined and alone as well ability to direct the differentiation of CD34+ cells into potent antigen-presenting dendritic cells in vitro. Our studies show that (1) mice vaccinated with a leukemogenic number of AML cells engineered to express B7.2 (B7.2-AML) or to secrete GM-CSF, IL-4, or TNF-α (GM-, IL-4–, TNF-α–AML) do not develop leukemia; (2) GM-AML cells are tumorigenic in sublethally irradiated SJL/J mice but not in Swiss nu/nu mice, indicating that killing of tumor cells is not T-cell–dependent; (3) vaccines with irradiated GM-AML, but not B7.2-, IL-4–, or TNF-α–AML cells, can elicit leukemia-specific protective and therapeutic immunity; and (4) in head-to-head comparison experiments, vaccination with irradiated GM-AML is more potent than B7.1-AML, curing 80% and providing 20% prolonged survival of the leukemic mice at week 2, as opposed to cures only up to 1 week with B7.1-AML vaccines. These preclinical data emphasize that GM-CSF gene immunotherapy deserves clinical evaluation in AML.

Gene Immunotherapy in Murine Acute Myeloid Leukemia: Granulocyte-Macrophage Colony-Stimulating Factor Tumor Cell Vaccines Elicit More Potent Antitumor Immunity Compared With B7 Family and Other Cytokine Vaccines

In an attempt to explore novel treatment modalities in acute myeloid leukemia (AML), we studied the role of costimulatory and cytokine gene immunotherapy in murine AML. We have previously shown that leukemic mice can be cured with CD80 transfected leukemic cells (B7.1-AML vaccine) administered early in the course of the disease and that the failure B7.1-AML vaccines administered late cannot be attributed to immunosuppression induced by tumor growth. CD8+ T cells, which are necessary for tumor rejection, are activated rather than suppressed during the first half of the leukemic course in nonvaccinated mice. In this report, we question whether CD86 (B7.2) or the cytokines granulocyte-macrophage colony-stimulating factor (GM-CSF), interleukin-4 (IL-4), or tumor necrosis factor-α (TNF-α) can improve the vaccination potential of AML cells. The choice of cytokines was based on their combined and alone as well ability to direct the differentiation of CD34+ cells into potent antigen-presenting dendritic cells in vitro. Our studies show that (1) mice vaccinated with a leukemogenic number of AML cells engineered to express B7.2 (B7.2-AML) or to secrete GM-CSF, IL-4, or TNF-α (GM-, IL-4–, TNF-α–AML) do not develop leukemia; (2) GM-AML cells are tumorigenic in sublethally irradiated SJL/J mice but not in Swiss nu/nu mice, indicating that killing of tumor cells is not T-cell–dependent; (3) vaccines with irradiated GM-AML, but not B7.2-, IL-4–, or TNF-α–AML cells, can elicit leukemia-specific protective and therapeutic immunity; and (4) in head-to-head comparison experiments, vaccination with irradiated GM-AML is more potent than B7.1-AML, curing 80% and providing 20% prolonged survival of the leukemic mice at week 2, as opposed to cures only up to 1 week with B7.1-AML vaccines. These preclinical data emphasize that GM-CSF gene immunotherapy deserves clinical evaluation in AML.

Molecular genetics of childhood leukemias

PURPOSE

This review summarizes the molecular genetics of childhood leukemias, with emphasis on pathogenesis and clinical applications.

DESIGN

We first describe the most common genetic events that occur in pediatric acute lymphoblastic leukemia (ALL), acute myeloid leukemia (AML), and chronic myeloid leukemia (CML). We then illustrate how these molecular alterations may be used to alter therapy.

RESULTS

In childhood ALL, the TEL-AML1 fusion and hyperdiploidy are both associated with excellent treatment outcomes and therefore identify patients who may be candidates for less intensive therapy. In contrast, MLL gene rearrangements and the BCR-ABL fusion confer a poor prognosis; these patients may be best treated by allogeneic bone marrow transplantation in first remission.

CONCLUSIONS

Although clinical features are important prognostic indicators, genetic alterations of leukemic blasts may be better predictors of outcome for acute leukemia patients. We therefore favor risk-adapted therapy based on classification schemes that incorporate both genetic and clinical features.

Backtracking leukemia to birth: identification of clonotypic gene fusion sequences in neonatal blood spots

Epidemiological evidence has suggested that some pediatric leukemias may be initiated in utero and, for some pairs of identical twins with concordant leukemia, this possibility has been strongly endorsed by molecular studies of clonality. Direct evidence for a prenatal origin can only be derived by prospective or retrospective detection of leukemia-specific molecular abnormalities in fetal or newborn samples. We report a PCR-based method that has been developed to scrutinize neonatal blood spots (Guthrie cards) for the presence of numerically infrequent leukemic cells at birth in individuals who subsequently developed leukemia. We demonstrate that unique or clonotypic MLL-AF4 genomic fusion sequences are present and detectable in neonatal blood spots from individuals who were diagnosed with acute lymphoblastic leukemia at ages 5 months to 2 years and, therefore, have arisen during fetal hematopoiesis in utero. This result provides unequivocal evidence for a prenatal initiation of acute leukemia in young patients. The method should be applicable to other fusion genes in children with common subtypes of leukemia and will be of value in attempts to unravel the natural history and etiology of this major subtype of pediatric cancer.

Acute lymphoblastic leukemia

Advances in the molecular and immunologic characterization of leukemic cells have greatly aided the diagnosis and risk assignment of ALL, as well as the monitoring of bone marrow samples for minimal residual disease. Currently, 75% of childhood cases have biologically and therapeutically relevant genetic abnormalities. Although gene discoveries in ALL have not been directly translated into effective therapy, there is every reason to believe that this disease will eventually yield to molecular intervention. In the meantime, efforts are being made to enhance the efficacy of existing regimens while reducing their toxic side effects. We have learned, for example, the following: high-dose methotrexate is more effective than lower-dose methotrexate, especially for T-cell ALL; patients who need drastic adjustment of mercaptopurine dosage due to thiopurine S-methyltransferase deficiency can be prospectively identified; dexrazoxane (ICRF-187) could reduce anthracycline cardiotoxicity; granulocyte colony-stimulating factor can shorten hospital stays for febrile neutropenia after intensive remission induction therapy; and prolonged low-dose epipodophyllotoxin treatment may reduce the risk of therapy-induced acute myeloid leukemia without compromising treatment efficacy. The challenge now is to identify specific treatments for genetically defined subtypes of ALL.