Sensitivity of Childhood Acute Lymphoblastic Leukemia (ALL) to Idarubicin Is Significantly Higher Than to Daunorubicin Treatment Based on Ex Vivo Apoptosis Induction.

Blood ◽  
2004 ◽  
Vol 104 (11) ◽  
pp. 4495-4495
Author(s):  
Aram Prokop ◽  
Banu Bagci ◽  
Guenaelle Lingfeld ◽  
Lucia Badiali ◽  
Karin Garbrecht ◽  
...  
Keyword(s):  
Acute Lymphoblastic Leukemia ◽  
Response Rate ◽  
De Novo ◽  
Ex Vivo ◽  
Lymphoblastic Leukemia ◽  
Cell Populations ◽  
Apoptosis Induction ◽  
Good Tolerability ◽  
Childhood All

Abstract Anthracyclines, especially daunorubicin, play a very important role in the treatment of acute lymphoblastic leukemia (ALL) and the relapsed ALL in childhood. In the present study, primary lymphoblasts isolated from 65 children with de novo ALL (median: 5.8 years; range: 1.9 – 16.9 years) and relapsed ALL (median: 12.7 years; range: 1.3 – 17.9 years) were treated with daunorubicin (10 mmol/l) or idarubicin (2 mmol/l) in vitro. We could show that both anthracylines induce apoptosis, as evidenced by measurement of genomic DNA fragmentation. Interestingly, daunorubicin only induced modest apoptosis, whereas idarubicin displayed a significantly stronger apoptosis inducing effect. Furthermore the treatment of daunorubicin-resistant lymphoblasts with idarubicin resulted in good response in most of the resistant cell populations. Out of the 65 patients analysed in this study 23 were female (13 de novo ALL, 10 relapsed ALL) and 42 were male (29 de novo ALL, 13 relapsed ALL). Primary lymphoblasts were obtained by bone marrow aspiration and separated by centrifugation over Ficoll. Within these cell populations following immunologic subgroups were found: 35 c-ALL, 10 pre-B-ALL, 7 pro-B-ALL, 10 T-ALL and 3 pre-T-ALL. Daunorubicin induced apoptosis in 33 out of 65 lymphoblast populations (response rate 50.8 %). Nevertheless, a far higher response rate was observed for idarubicin with 59/65 (90,8 %) (p < 0.008), if response is defined as apoptosis induction higher than 1 %. Daunorubicin-resistance was found in 32/65 (49,2 %), resistance to both was observed in 6/65 (9,2 %). Treatment of daunorubicin-resistant lymphoblasts with idarubicin resulted in significant apoptosis induction in 26 out of 32 cell populations (81,3 %). We clearly demonstrated here that the in vitro treatment of lymphoblasts from children with de novo or relapsed ALL with idarubicin induces significantly higher response rates than daunorubicin treatment. The ex vivo sensitivity of daunorubicin-resistant lymphoblasts of childhood ALL to idarubicin treatment reflects the better potency of idarubicin to induce apoptosis and to overcome daunorubicin resistance. These data prompted us to study the clinical relevance of idarubicin in ongoing clinical trials to improve existing therapeutic regiments. First clinical data point to a good tolerability of idarubicin in the treatment of relapsed ALL in childhood.

New Pinostilbene Analogues Overcome Anthracycline Resistance in Acute Lymphoplastic Leukemia Ex Vivo.

Blood ◽  
2006 ◽  
Vol 108 (11) ◽  
pp. 4403-4403
Author(s):  
Banu Katik ◽  
Anja Selig ◽  
Janna Velder ◽  
Elvira E. Shults ◽  
Thomas Wieder ◽  
...  
Keyword(s):  
Acute Lymphoblastic Leukemia ◽  
Cell Lines ◽  
Response Rate ◽  
De Novo ◽  
Ex Vivo ◽  
Lymphoblastic Leukemia ◽  
Response Rates ◽  
Cell Populations ◽  
Apoptosis Induction ◽  
Anthracycline Resistance

Abstract Anthracylines play a very important role in the treatment of acute lymphoblastic leukemia (ALL) and relapsed ALL in childhood, however resistance to anthracyclines leads to a poor prognosis. In the present study, we have synthesized two new pinostilbene analogues, i.e. trans-3,4′-dihydroxy-5-methoxystilbene and (E)-resveratrol 4′-O-ß-D-glucopyranoside, which are able to overcome anthracycline resistance in childhood acute lymphoblastic leukemia (ALL) ex vivo and induce apoptosis in established leukemia cell lines via mitochondrial pathway. Apoptosis induction has been investigated by flowcytometric measurement of DNA-fragmentation [LC 50: 10 μM for (1) and (2)], mitochondrial membrane potential reduction and phosphatedylserin-staining on cell membrane surface. Cell death by necrosis could be excluded by a lactatdehydrogenase-release assay. For the first time we analysed the antileukemic and chemopreventive potentials of the pinostilbene analogues (1) and (2) ex vivo in a significant number of primary lymphoblasts of patients suffering from childhood ALL. Patients: Primary lymphoblasts isolated from 22 children with de novo ALL (median: 6.8 years; range 0,6–16.9 years) and relapsed ALL (median:7.2 years) were tested for ex vivo drug response with the anthracyclines daunorubicin (10 μmol/l) and doxorubicin (10 μmol/l) and two new pinostilbene analogues (1) and (2) (10μmol/l), according to their LC50 values in established cell lines. We could demonstrate in these primary cells that the pinostilbenes (1) and (2) were even more effective as compared with the anthracyclines. Out of 22 patients 14 were female (14 de novo ALL) and 8 were male (6 de novo ALL, 2 relapsed ALL). Within these cell populations following immunologic subgroups were found: c-ALL, pre-B-ALL, pro-B-ALL, T-ALL and pre-T-ALL. Results: Daunorubicin induced apoptosis in 6 out of 22 lymphoblast populations (response rate 27,3 %). A similar response rate was observed after treatment with doxorubicin: only 5 of 22 lymphoblast populations responded (22,7%). Nevertheless, far higher response rates were observed for (1) with 11/15 (73,3 %; p<0.005) and for (2) with 15/17 (88,2%; p<0.0002, all p-values by t-test). Interestingly, treatment of daunorubicin-resistant lymphoblasts resulted in significant apoptosis induction in 6 out of 10 cell populations after treatment with compound (1) (response rate 60 %) and in 6/6 after treatment with compound (2) (response rate 100%). Furthermore, pinostilbene (2) showed significant synergistic activity with daunorubicin in 2 of 3 lymphoblast populations. We clearly demonstrated that the ex vivo treatment of lymphoblasts from children with de novo and relapsed ALL with the new pinostilbenes (1) and (2) induced significantly higher response rates than daunorubicin or doxorubicin treatment. In conclusion, the high ex vivo sensitivity of anthracycline resistant leukemia cells to pinostilbene treatment reveals the great proapoptotic and chemopreventive potential of this new class of antileukemic agents.

scholarly journals In vitro cellular drug resistance in children with relapsed/refractory acute lymphoblastic leukemia

Blood ◽  
1995 ◽  
Vol 86 (10) ◽  
pp. 3861-3868 ◽  
Author(s):  
E Klumper ◽  
R Pieters ◽  
AJ Veerman ◽  
DR Huismans ◽  
AH Loonen ◽  
...  
Keyword(s):  
Drug Resistance ◽  
Acute Lymphoblastic Leukemia ◽  
Poor Prognosis ◽  
De Novo ◽  
Lymphoblastic Leukemia ◽  
Childhood All ◽  
Acquired Drug Resistance ◽  
The Poor ◽  
Response To Chemotherapy

Cellular drug resistance is thought to be an important cause of the poor prognosis for children with relapsed or refractory acute lymphoblastic leukemia (ALL), but it is unknown when, to which drugs, and to what extent resistance is present. We determined in vitro resistance to 13 drugs with the MTT assay. Compared with 141 children with initial ALL, cells from 137 children with relapsed ALL were significantly more resistant to glucocorticoids, L-asparaginase, anthracyclines, and thiopurines, but not to vinca-alkaloids, cytarabine, ifosfamide, and epipodophyllotoxins. Relapsed ALL cells expressed the highest level of resistance to glucocorticoids, with a median level 357- and >24-fold more resistant to prednisolone and dexamethasone, respectively, than initial ALL cells, whereas the resistance ratios for the other drugs differed from 0.8- to 1.9-fold, intraindividual comparisons between initial and relapsed samples from 16 children with ALL showed that both de novo and acquired drug resistance were involved. Specific in vitro drug-resistance profiles were associated with high-risk relapsed ALL groups. In vitro drug resistance was also related to the clinical response to chemotherapy in relapsed/refractory childhood ALL. We conclude that drug resistance may explain the poor prognosis for children with relapsed/refractory ALL. These day may be helpful to design alternative treatment regimens for relapsed childhood ALL.

TPEN Selectively Eliminates Lymphoblastic B cells from Bone Marrow Pediatric Acute Lymphoblastic Leukemia Patients

2021 ◽  
Author(s):  
Miguel Mendivil-Perez ◽  
Carlos Velez-Pardo ◽  
Lina Maria Quiroz-Duque ◽  
Alexandra Restrepo-Rincon ◽  
Natalia Andrea Valencia-Zuluaga ◽  
...  
Keyword(s):  
Bone Marrow ◽  
Acute Lymphoblastic Leukemia ◽  
Anticancer Agents ◽  
Pediatric Patients ◽  
De Novo ◽  
Ex Vivo ◽  
Lymphoblastic Leukemia ◽  
Leukemic Cell ◽  
Leukemia Cells

B-cell acute lymphoblastic leukemia (B-ALL) is a hematologic disorder characterized by the abnormal proliferation and accumulation of immature B-lymphoblasts arrested at various stages of differentiation. Despite advances in treatment, a significant percentage of pediatric patients with precursor B-ALL still relapse. Therefore, alternative therapies are needed to improve the cure rates for pediatric patients. TPEN (N, N, N&rsquo;, N&rsquo;-tetrakis(2-pyridylmethyl)-ethylenediamine).is a pro-oxidant agent capable of selectively inducing apoptosis in leukemia cells. Consequently, it has been suggested that TPEN could be a potential agent for oxidative therapy. However, it is not yet known whether TPEN can selectively destroy leukemia cells in a more disease-like model, for example, the bloodstream and bone marrow (BM), in vitro. This investigation is an extension of a previous study that dealt with the effect of TPEN on ex vivo isolated/purified refractory B-ALL cells. Here, we evaluated the effect of TPEN on whole BM from nonleukemic patients (control) or pediatric patients diagnosed with de novo B-ALL or refractory B-ALL cells by analyzing the hematopoietic cell lineage marker CD34/CD19. Although TPEN was innocuous to nonleukemic BM (n=3), we found that TPEN significantly induced apoptosis in de novo (n = 5) and refractory B-ALL (n = 6) leukemic cell populations. Moreover, TPEN significantly increased the counts of cells positive for the oxidation of the stress sensor protein DJ-1, a sign of the formation of H2O2, and significantly increased the counts of cells positive for the pro-apoptotic proteins TP53, PUMA, and CASPASE-3 (CASP-3), indicative of apoptosis, in B-ALL cells. We demonstrate that TPEN selectively eliminates B-ALL cells independent of age, diagnosis status (de novo or refractory), sex, karyotype, or immunophenotype. Understanding TPEN-induced cell death in leukemia cells provides insight into more effective therapeutic oxidation-inducing anticancer agents.

scholarly journals Axitinib in Ponatinib-Resistant B-Cell Acute Lymphoblastic Leukemia Harboring a T315L Mutation

2020 ◽  
Vol 21 (24) ◽  
pp. 9724
Author(s):  
Valentina Giudice ◽  
Andrea Ghelli Luserna di Rorà ◽  
Bianca Serio ◽  
Roberto Guariglia ◽  
Maria Benedetta Giannini ◽  
...  
Keyword(s):  
Clinical Trials ◽  
Acute Lymphoblastic Leukemia ◽  
Randomized Clinical Trials ◽  
Ex Vivo ◽  
Lymphoblastic Leukemia ◽  
Fatal Outcome ◽  
Philadelphia Chromosome ◽  
Dose Finding ◽  
Third Generation

Adult acute lymphoblastic leukemia (ALL) with BCR-ABL1 rearrangement (Philadelphia chromosome, Ph) is a hematological aggressive disease with a fatal outcome in more than 50% of cases. Tyrosine kinase inhibitors (TKIs) targeting the activity of BCR-ABL1 protein have improved the prognosis; however, relapses are frequent because of acquired somatic mutations in the BCR-ABL1 kinase domain causing resistance to first, second and third generation TKIs. Axitinib has shown in vitro and ex vivo activity in blocking ABL1; however, clinical trials exploring its efficacy in ALL are missing. Here, we presented a 77-year-old male with a diagnosis of Ph positive ALL resistant to ponatinib and carrying a rare threonine to leucine (T315L) mutation on BCR-ABL1 gene. The patient was treated with axitinib at 5 mg/twice daily as salvage therapy showing an immediate although transient benefit with an overall survival of 9.3 months. Further dose-finding and randomized clinical trials are required to assess the real efficacy of axitinib for adult Ph positive ALL resistant to third generation TKIs.

scholarly journals TEL/AML-1 dimerizes and is associated with a favorable outcome in childhood acute lymphoblastic leukemia

Blood ◽  
1996 ◽  
Vol 88 (11) ◽  
pp. 4252-4258 ◽  
Author(s):  
TW McLean ◽  
S Ringold ◽  
D Neuberg ◽  
K Stegmaier ◽  
R Tantravahi ◽  
...  
Keyword(s):  
Acute Lymphoblastic Leukemia ◽  
Lymphoblastic Leukemia ◽  
Chromosomal Translocation ◽  
Fusion Transcript ◽  
Childhood Acute Lymphoblastic Leukemia ◽  
Childhood All ◽  
Polymerase Chain ◽  
B Lineage

Abstract Polymerase chain reaction-based screening of childhood acute lymphoblastic leukemia (ALL) samples showed that a TEL/AML1 fusion transcript was detected in 27% of all cases, representing the most common known gene rearrangement in childhood cancer. The TEL/AML1 fusion results from a t(12;21)(p13;q22) chromosomal translocation, but was undetectable at the routine cytogenetic level. TEL/AML1-positive patients had exclusively B-lineage ALL, and most patients were between the ages of 2 and 9 years at diagnosis. Only 3/89 (3.4%) adult ALL patients were TEL/AML1-positive. Most importantly, TEL/AML1-positive children had a significantly lower rate of relapse compared with TEL/AML1-negative patients (0/22 v 16/54, P = .004). Co- immunoprecipitation experiments demonstrated that TEL/AML-1 formed homodimers in vitro, and heterodimerized with the normal TEL protein when the two proteins were expressed together. The elucidation of the precise mechanism of transformation by TEL/AML1 and the role of TEL/AML1 testing in the treatment of childhood ALL will require additional studies.

scholarly journals Doxorubicin/Nucleophosmin Binding Protein-Conjugated Nanoparticle Enhances Anti-leukemia Activity in Acute Lymphoblastic Leukemia Cells in vitro and in vivo

2021 ◽  
Vol 12 ◽  
Author(s):  
Donghui Gan ◽  
Yuwen Chen ◽  
Zhengjun Wu ◽  
Liping Luo ◽  
Shimuye Kalayu Yirga ◽  
...  
Keyword(s):  
Drug Delivery ◽  
Acute Lymphoblastic Leukemia ◽  
Drug Delivery System ◽  
Delivery System ◽  
Binding Protein ◽  
Lymphoblastic Leukemia ◽  
Multidrug Resistant ◽  
Apoptosis Induction

Acute lymphoblastic leukemia (ALL) is an aggressive malignancy. Adults with ALL have more than 50% relapse rates. We have previously validated that overexpression of nucleophosmin (NPM) is involved in the multidrug resistance (MDR) development during ALL; and a synthetically engineered recombinant NPM binding protein (NPMBP) has been developed in our group; NPMBP and doxorubicin (DOX) can be conjugated in a nanoparticle-based drug delivery system named DOX-PMs-NPMBP to counteract MDR during ALL. Here, we evaluated the antileukemia potential of DOX-PMs-NPMBP in resistant ALL cells. This study demonstrates that DOX-PMs-NPMBP significantly enhances chemosensitivity to DOX in ALL cells. Despite at variable concentrations, both resistant and primary ALL cells from relapsed patients were sensitive to DOX-PMs-NPMBP. In detail, the half maximal inhibitory concentration (IC50) values of DOX-PMs-NPMBP were between 1.6- and 7.0-fold lower than those of DOX in cell lines and primary ALL cells, respectively; and apoptotic cells ratio was over 2-fold higher in DOX-PMs-NPMBP than DOX. Mechanistically, p53-driven apoptosis induction and cell cycle arrest played essential role in DOX-PMs-NPMBP-induced anti-leukemia effects. Moreover, DOX-PMs-NPMBP significantly inhibited tumor growth and prolonged mouse survival of ALL xenograft models; and no systemic toxicity occurrence was observed after treatment during follow-up. In conclusion, these data indicate that DOX-PMs-NPMBP may significantly exert growth inhibition and apoptosis induction, and markedly improve DOX antileukemia activity in resistant ALL cells. This novel drug delivery system may be valuable to develop as a new therapeutic strategy against multidrug resistant ALL.

L-arginine depletion by PEG-arginase I, a new potential therapy for acute lymphoblastic leukemia.

2012 ◽  
Vol 30 (15_suppl) ◽  
pp. 6580-6580
Author(s):  
Ofelia Crombet Ramos ◽  
Claudia Hernandez ◽  
Kevin Morrow ◽  
John T. Cole ◽  
Paulo Rodriguez
Keyword(s):  
Cell Proliferation ◽  
Acute Lymphoblastic Leukemia ◽  
T Cell ◽  
De Novo ◽  
Remission Rate ◽  
Lymphoblastic Leukemia ◽  
Arginase I

6580 Background: Advances in therapies have resulted in an overall complete remission rate of approximately 85% for childhood acute lymphoblastic leukemia (ALL). In contrast, the overall remission rate of adults with leukemia continues to be poor, only about 40% in cases of T cell-ALL (T-ALL). Therefore, it is imperative to generate new therapies that alone or in combination with other treatments could potentially increase the percentages of complete responders or be used to treat the refractory ALL population. Our published results show that a pegylated form of human arginase I (peg-Arg I) prevented T-ALL cell proliferation in vitro and in vivo through the induction of tumor cell apoptosis. Interestingly, the anti-leukemic effects induced by peg-Arg I did not affect the anti-tumor activity of normal T cells, suggesting an anti-tumor specific effect. Our hypothesis states that peg-Arg I has an anti-tumoral effect on B-ALL and T-ALL cells in vitro and that the sensitivity of ALL cells to peg-Arg I depends on their expression of argininosuccinate synthase (ASS) and their ability to produce L-arginine de novo from citrulline. Methods: Malignant T cell proliferation was tested using nonradioactive cell proliferation yellow tretrazolium salt kit. Apoptosis studies were based on the expression of annexin V. Western blot assays were conducted to determine enzymatic expression in different cell lines. Results: The results of our in vitro experiments showed that peg-Arg I had a pro-apoptotic and anti-proliferattive effect on B-ALL cells similar to the one previously seen on T-ALL cells. These effects can be overcome in cell lines able that express ASS and therefore to produce L-arginine de novo. Conclusions: Our results suggest the role of ASS in the ALL-apoptosis induced by peg-Arg-I. Our next steps include: _Understand why ASS-expressing ALL cells do not undergo apoptosis when cultured with peg-Arg-I_Determine the role of ASS in the anti-leukemic effect induced by peg-Arg-I in vivo. Completion of this research is expected to lead to a better understanding of how peg-Arg-I kills ALL cells and could provide the foundation for a novel therapy for ALL patients.

scholarly journals In Vitro Drug Sensitivity Testing Can Predict Induction Failure and Early Relapse of Childhood Acute Lymphoblastic Leukemia

Blood ◽  
1997 ◽  
Vol 89 (8) ◽  
pp. 2959-2965 ◽  
Author(s):  
Teruaki Hongo ◽  
Shuhei Yajima ◽  
Minoru Sakurai ◽  
Yasuo Horikoshi ◽  
Ryoji Hanada
Keyword(s):  
Drug Resistance ◽  
Acute Lymphoblastic Leukemia ◽  
Drug Sensitivity ◽  
Lymphoblastic Leukemia ◽  
Sensitivity Testing ◽  
Childhood All ◽  
Drug Sensitivity Testing ◽  
Induction Failure ◽  
Sensitive Group

Abstract It is vital to develop effective therapy for children with acute lymphoblastic leukemia (ALL), in whom no remission occurs or who suffer relapse with current protocols. Cellular drug resistance is thought to be an important cause of induction failure and relapse. We performed in vitro tests of bone marrow samples in 196 children with newly diagnosed ALL with a 4-day culture and a methyl-thiazol-tetrazolium assay. We tested 16 drugs and calculated the 70% lethal dose (LD70) for 14 drugs and the leukemic cell survival (LCS) rate for dexamethasone and prednisolone. For each single drug, patients were classified into two groups, sensitive or resistant, by median concentration of LD70 or LCS. When patients were classified into three groups by sensitivity to four drugs of DPAV (dexamethasone, prednisolone, L-asparaginase, and vincristine), 3-year event-free survival (EFS; 95% confidence intervals) of the super sensitive group (SS; sensitive to all 4 drugs) was 0.833 (0.690 to 0.976), that of the intermediate sensitive group (IS; sensitive to 2 or 3 drugs) was 0.735 (0.609 to 0.863), and that of the relatively resistant group (RR; sensitive to no drugs or to 1 drug) was 0.541 (0.411 to 0.670; P = .0008). We then investigated the relationship between the above four-drug sensitivity and the time of relapse. The SS and IS patients tended to maintain continuous complete remission, and RR patients tended to undergo induction failure and early and late relapse (P = .004). Initial white blood cell count, immunologic classification, and age were also predictive factors, but the patient numbers showed no statistical correlation between these factors and the four-drug sensitivity groups (SS, IS, and RR). When we took three groups SS/IS/RR and investigated the EFS for various clinical groups, DPAV sensitivity strongly influenced EFS in the standard-risk ALL (P = .016). In vitro drug sensitivity testing provides additional prognostic information about childhood ALL, and early detection of drug resistance at the time chemotherapy commences may provide a successful strategy for individualizing treatment, as the results indicate de novo resistance to front-line drugs and suggest alternative, second-line drugs.

scholarly journals Targeting Telomere Biology in Acute Lymphoblastic Leukemia

2021 ◽  
Vol 22 (13) ◽  
pp. 6653
Author(s):  
Axel Karow ◽  
Monika Haubitz ◽  
Elisabeth Oppliger Leibundgut ◽  
Ingrid Helsen ◽  
Nicole Preising ◽  
...  
Keyword(s):  
Acute Lymphoblastic Leukemia ◽  
High Risk ◽  
T Lymphocytes ◽  
Ex Vivo ◽  
Lymphoblastic Leukemia ◽  
Genetic Alterations ◽  
Adult Patients ◽  
Pediatric All ◽  
B And T Lymphocytes

Increased cell proliferation is a hallmark of acute lymphoblastic leukemia (ALL), and genetic alterations driving clonal proliferation have been identified as prognostic factors. To evaluate replicative history and its potential prognostic value, we determined telomere length (TL) in lymphoblasts, B-, and T-lymphocytes, and measured telomerase activity (TA) in leukocytes of patients with ALL. In addition, we evaluated the potential to suppress the in vitro growth of B-ALL cells by the telomerase inhibitor imetelstat. We found a significantly lower TL in lymphoblasts (4.3 kb in pediatric and 2.3 kb in adult patients with ALL) compared to B- and T-lymphocytes (8.0 kb and 8.2 kb in pediatric, and 6.4 kb and 5.5 kb in adult patients with ALL). TA in leukocytes was 3.2 TA/C for pediatric and 0.7 TA/C for adult patients. Notably, patients with high-risk pediatric ALL had a significantly higher TA of 6.6 TA/C compared to non-high-risk patients with 2.2 TA/C. The inhibition of telomerase with imetelstat ex vivo led to significant dose-dependent apoptosis of B-ALL cells. These results suggest that TL reflects clonal expansion and indicate that elevated TA correlates with high-risk pediatric ALL. In addition, telomerase inhibition induces apoptosis of B-ALL cells cultured in vitro. TL and TA might complement established markers for the identification of patients with high-risk ALL. Moreover, TA seems to be an effective therapeutic target; hence, telomerase inhibitors, such as imetelstat, may augment standard ALL treatment.

scholarly journals Whole Transcriptome Sequencing Identified a Distinct Subtype of Acute Lymphoblastic Leukemia with Abnormalities of CREBBP and EP300

Blood ◽  
2016 ◽  
Vol 128 (22) ◽  
pp. 3912-3912
Author(s):  
Hui Zhang ◽  
Maoxiang Qian ◽  
Shirley, Kow Yin Kham ◽  
Shuguang Liu ◽  
Chuang Jiang ◽  
...  
Keyword(s):  
Acute Lymphoblastic Leukemia ◽  
Conflicts Of Interest ◽  
Lymphoblastic Leukemia ◽  
Chromosomal Rearrangements ◽  
Ectopic Expression ◽  
Cytotoxic Agents ◽  
Hematopoietic Stem ◽  
Exon 2 ◽  
Childhood All

Abstract While acute lymphoblastic leukemia (ALL) is a prototype of cancer that can be cured by chemotherapy alone, current ALL treatment regimens rely primarily on conventional cytotoxic agents with significant acute and long-term side effects. Better understanding of genomic landscape of ALL is critical for developing molecularly targeted therapy and implementing genomics-based precision medicine in this cancer. In particularly, sentinel chromosomal translocations are common in ALL and often involve key transcription factors important for hematopoiesis. Epigenetic regulator genes are also frequently targeted by somatic genomic alterations such as sequence mutations (e.g., CREBBP) and gene fusions (e.g., MLL, EP300). To comprehensively define transcriptomic abnormalities in childhood ALL, we performed RNA-seq of an unselected cohort of 231 children enrolled on the MaSpore frontline ALL protocols in Singapore or Malaysia. In total, we identified 58 putatively functional and predominant fusion genes in 125 patients (54.1%), the majority of which have not been reported previously. In particular, we described a distinct ALL subtype with a characteristic gene expression signature driven by chromosomal rearrangements of the ZNF384 gene with different partners (i.e., histone acetyl-transferases EP300 and CREBBP, TAF15, and TCF3). In 9 of 11 ALL cases with ZNF384 rearrangements, the breakpoint in this gene was invariably between exon 2 and exon 3, resulting in deletion of the 5'-UTR and then in-frame fusion of the entire ZNF384 coding sequence with the partner genes. The top two most significantly up-regulated genes in the ZNF384-rearranged group were CLCF1 and BTLA, whose expression levels were 15.5- and 15.0-fold higher than in ALL cases with wildtype ZNF384, respectively. In fact, ZNF384 binding was identified within the CLCF1 and BTLA loci (particularly the promoter regions) by chromatin immunoprecipitation sequencing in B lymphoblasoid cells. Using luciferase transcription driven by CLCF1 promoter in HEK293T cells as a model system, we observed significantly greater transcription activity with EP300-ZNF384 fusion compared to cells expressing wildtype ZNF384, suggesting that this chimeric gene resulted in gain of ZNF384 function. Similar results were obtained with luciferase transcription assay driven by the BTLA promoter. In human ALL cells, CLCF1 and BTLA promoter activities were consistently and significantly higher in ZNF384-rearranged ALL than in ALL cell line with wildtype ZNF384. To examine the effects of ZNF384 fusion on hematopoietic stem and progenitor cell (HSPCs) function, we also evaluated colony forming potential of HSPC in vitro upon ectopic expression of ZNF384 fusions. While there was marked suppression of colonies from myeloid and erythoid lineages, expression of EP300-ZNF384 or CREBBP-ZNF384 significantly stimulated preB cell colony formation. However, neither EP300- nor CREBBP-ZNF384 fusion was able to transform mouse hematopoietic precursor cell Ba/f3 in vitro, but instead increased the transforming potential of other oncogenic mutations (NRASG12D). EP300-ZNF384 and CREBBP-ZNF384 fusion proteins lacked the histone acetyltransferase (HAT) domain, and showed only 25% and 10% of HAT activity of full-length EP300 and CREBBP, respectively, with dominant-negative effects. Also, expression of EP300-ZNF384 led to significant decrease in global H3 acetylation in Ba/f3 cells in vitro. Finally, in NRASG12D-transformed Ba/f3 cells, co-expression of EP300-ZNF384 or CREBBP-ZNF384 substantially potentiated cytotoxic effects of histone deacetylase inhibitor vorinostat. Similarly, in a panel of human ALL cell lines, ZNF384-rearrangement was also associated with increased sensitivity to vorinostat, suggesting that some ZNF384-rearranged ALL may benefit from therapeutic agents targeting histone acetylation regulation. In conclusion, our results indicate that gene fusion is the major class of genomic abnormalities in childhood ALL and chromosomal rearrangements involving EP300 and CREBBP may cause global epigenetic deregulation in ALL with potentials for therapeutic targeting. Disclosures No relevant conflicts of interest to declare.

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