The Wee1 Inhibitor, MK-1775, Sensitizes Leukemic Cells to Different Antineoplastic Drugs Interfering with DNA Damage Response Pathway

Blood ◽  
2015 ◽  
Vol 126 (23) ◽  
pp. 1276-1276 ◽  
Author(s):  
Andrea Ghelli Luserna Di Rora ◽  
Ilaria Iacobucci ◽  
Neil Beeharry ◽  
Simona Soverini ◽  
Cristina Papayannidis ◽  
...  
Keyword(s):  
Cell Cycle ◽  
Dna Damage ◽  
Acute Lymphoblastic Leukemia ◽  
Cell Viability ◽  
Cell Lines ◽  
Lymphoblastic Leukemia ◽  
Genetic Alterations ◽  
Additive Effect ◽  
Proliferation Index ◽  
Induction Of Apoptosis

Abstract Due to inadequate treatments, the survival rate of adult Acute Lymphoblastic Leukemia (ALL) patients with the exclusion of patients with particular genetic alterations, like the Philadelphia positive patients, is still very low. Moreover even the rate of patient that responds to specific treatment develops relapses during their life. Thus there is a need to improve the efficacy of conventional therapy and to discover novel specific targets. In eukaryotic cells Wee1, ATR/Chk1 and ATM/Chk2 are three pathways involved in cell cycle regulation, DNA damages response and DNA repair. Wee1 is a checkpoint kinase, involved mainly in the regulation of G2/M transition through the inhibitory phosphorylation of both Cyclin-dependent kinase 1 (CDK1) and 2 (CDK2) respectively. This study evaluates the effectiveness of MK-1775, a selective Wee1 inhibitor, as a monotherapy and as chemosensitizer agent for the treatment of B-/T-Acute Lymphoblastic Leukemia. Human B (BV-173, SUPB-15, NALM-6, NALM-19 and REH) and T (MOLT-4, RPMI-8402 and CEM) ALL cell lines were tested in this study. MK-1775 alone strongly reduced the cell viability in a dose and time-dependent manner in all the cell lines treated. The anti-proliferative activity of MK-1775 was accompanied by an increase in apoptotic cells (AnnexinV/Pi staining) and by DNA damage markers (gH2AX and Parp-1 cleavage). Moreover the inhibition of Wee1 disrupted the cell cycle profile by arresting the cells in late S and in G2/M phase. We hypothesized that targeting Chk1, a kinase upstream, of Wee1, would be more effective in reducing cell proliferation. Indeed, the concomitant inhibition of Chk1 and Wee1 kinases, using the PF-0477736 in combination with MK-1775, synergized in the reduction of the cell viability, inhibition of the proliferation index and induction of apoptosis. Moreover the immunofluorescence staining for the DNA damage marker gH2AX and the mitotic marker phosphor-Histone H3 showed that co-treatment with MK-1775 and PF-0477736 induced cell death by mitotic catastrophe. We undertook further studies to understand the immediate clinical potential of the compound, thus MK-1775 was combined with different drugs (Clofarabine, Bosutinib Authentic, and a particular isomer of this compound).The combination between MK-1775 and clofarabine showed an additive effect in terms of reduction of the cell viability and induction of apoptosis. Finally the Wee1 inhibitor was combined with the tyrosine kinase inhibitors Bosutinib and Bos-isomer (Bos-I). Both the isomers in combination with MK-1775 showed an additive effect in term of reduction of the cell viability. Interestedly the cytotoxic effect of Bos-I was stronger on the Philadelphia-negative cell lines in comparison to the positive counterpart. Western blot analysis highlighted that this compound, but not the Bosutinib authentic, interfered with the Chk1/Chk2 and Wee1 pathway. This supported our previous studies showing that Bosutinib and its isomer possess off-target effects against both Wee1 and Chk1 kinases and thus maybe used as a chemosensitizer (Beeharry et al. Cell Cycle 2014). The results of this study in our opinion identify the Wee1 kinase as a promising target for the treatment of ALL not only as a monotherapy but also as chemosensitizer agent to increase the cytotoxicity of different kind of drugs already used in clinical trials. Disclosures Soverini: Novartis, Briston-Myers Squibb, ARIAD: Consultancy. Martinelli:Novartis: Consultancy, Speakers Bureau; Ariad: Consultancy; AMGEN: Consultancy; ROCHE: Consultancy; BMS: Consultancy, Speakers Bureau; MSD: Consultancy; Pfizer: Consultancy.

The Inhibition of Checkpoint Kinase 1 As a Promising Strategy to Increase the Effectiveness of Different Treatments in Acute Lymphoblastic Leukemia

Blood ◽  
2015 ◽  
Vol 126 (23) ◽  
pp. 2478-2478
Author(s):  
Andrea Ghelli Luserna Di Rora ◽  
Ilaria Iacobucci ◽  
Enrica Imbrogno ◽  
Enrico Derenzini ◽  
Anna Ferrari ◽  
...  
Keyword(s):  
Cell Cycle ◽  
Acute Lymphoblastic Leukemia ◽  
Cell Viability ◽  
Cytotoxic Activity ◽  
Cell Lines ◽  
Propidium Iodide ◽  
Lymphoblastic Leukemia ◽  
Single Agent ◽  
Dna Damages ◽  
Checkpoint Kinase

Abstract Nowadays the effectiveness of the treatments for adult Acute Lymphoblastic Leukemia (ALL) patients is still inadequate and frequently many patients after years of response to treatments develop relapses. Thus there is a need to find novel targets for specific therapies and to maximize the effect of the actual treatments. Recently different Checkpoint Kinase (Chk)1/Chk2 inhibitors has been assessed for the treatment of different type of cancers but only few studies have been performed on hematological diseases. We evaluated the effectiveness of the Chk1 inhibitor, LY2606368, as single agent and in combination with tyrosine kinase inhibitors (imatinib and dasatinib) or with the purine nucleoside antimetabolite clofarabine in B-/T- acute lymphoblastic leukemia (ALL) cell lines and in primary blasts. Human B (BV-173, SUPB-15, NALM-6, NALM-19 and REH) and T (MOLT-4, RPMI-8402 and CEM) ALL cell lines were incubated with increasing concentrations of drug (1-100 nM) for 24 and 48 hours and the reduction of the cell viability was evaluated using WST-1 reagent. LY2606368 deeply reduced the cell viability in a dose and time dependent manner in all the cell lines, with the BV-173 (6.33 nM IC50 24hrs) and RPMI-8402 (8.07 nM IC50 24hrs) being the most sensitive while SUP-B15 (61.4 nM IC50 24hrs) and REH (96.7 nM IC50 24hrs) being the less sensitive cell lines. Moreover the sensitivity to the compound was no correlated with the different sub-type of ALL or with the mutational status of p53, which is a marker of the functionality of the G1/S checkpoint. The cytotoxic activity was confirmed by the significant increment of apoptosis cells (Annexin V/Propidium Iodide), by the increment of gH2AX foci and by the activation of different apoptotic markers (Parp-1 and pro-Caspase3 cleavage). To understand the relationship between the activation of apoptosis and the effect on cell cycle and to identify hypothetical mechanisms of death, different cell cycle analyses were performed (Propidium Iodide staining). The inhibition of Chk1, deeply changed the cell cycle profile. Indeed in all the cell lines the percentage of cells in S phase and in G2/M phase were reduced by the treatment while the numbers of cells in sub-G1 and G1 phase were increased. The hypothetical function of LY2606368 as a chemosensitizer agent was evaluated combining the compound with different drugs normally used in clinical trials. For each drugs the combination strongly reduced the cell viability when compared to the cytotoxic effect of the single drugs. Moreover the combination showed an additive efficacy in term of induction of DNA damages as showed by the increase number of gH2AX foci and the activation of pChk1 (ser 317). The results found on the cell lines were confirmed also using primary leukemic blast isolated from adult Philadelphia-positive ALL patients. Indeed LY2606368 as single agent or in combination with the Tki, imatinib, was able to deeply reduce the cell viability and to induce DNA damages (gH2AX foci). In conclusion LY2606368 showed a strong cytotoxic activity on B-/T-All cell lines and primary blasts as single agent and in combination with other drugs. In our opinion this data are the basis for a future clinical evaluation of this compound in the treatment of leukemia. Supported by ELN, AIL, AIRC, progetto Regione-Università 2010-12 (L. Bolondi), FP7 NGS-PTL project. Disclosures Soverini: Novartis, Briston-Myers Squibb, ARIAD: Consultancy. Cavo:JANSSEN, CELGENE, AMGEN: Consultancy. Martinelli:ROCHE: Consultancy; Novartis: Consultancy, Speakers Bureau; BMS: Consultancy, Speakers Bureau; Pfizer: Consultancy; Ariad: Consultancy; AMGEN: Consultancy; MSD: Consultancy.

scholarly journals Synergism Through WEE1 and CHK1 Inhibition in Acute Lymphoblastic Leukemia

Cancers ◽  
2019 ◽  
Vol 11 (11) ◽  
pp. 1654 ◽  
Author(s):  
Ghelli Luserna Di Rorà ◽  
Bocconcelli ◽  
Ferrari ◽  
Terragna ◽  
Bruno ◽  
...  
Keyword(s):  
Cell Cycle ◽  
Cell Death ◽  
Acute Lymphoblastic Leukemia ◽  
Cell Lines ◽  
Therapeutic Strategy ◽  
Synthetic Lethality ◽  
Ex Vivo ◽  
Lymphoblastic Leukemia ◽  
Cell Cycle Checkpoint ◽  
Induction Of Apoptosis

Introduction: Screening for synthetic lethality markers has demonstrated that the inhibition of the cell cycle checkpoint kinases WEE1 together with CHK1 drastically affects stability of the cell cycle and induces cell death in rapidly proliferating cells. Exploiting this finding for a possible therapeutic approach has showed efficacy in various solid and hematologic tumors, though not specifically tested in acute lymphoblastic leukemia. Methods: The efficacy of the combination between WEE1 and CHK1 inhibitors in B and T cell precursor acute lymphoblastic leukemia (B/T-ALL) was evaluated in vitro and ex vivo studies. The efficacy of the therapeutic strategy was tested in terms of cytotoxicity, induction of apoptosis, and changes in cell cycle profile and protein expression using B/T-ALL cell lines. In addition, the efficacy of the drug combination was studied in primary B-ALL blasts using clonogenic assays. Results: This study reports, for the first time, the efficacy of the concomitant inhibition of CHK1/CHK2 and WEE1 in ALL cell lines and primary leukemic B-ALL cells using two selective inhibitors: PF-0047736 (CHK1/CHK2 inhibitor) and AZD-1775 (WEE1 inhibitor). We showed strong synergism in the reduction of cell viability, proliferation and induction of apoptosis. The efficacy of the combination was related to the induction of early S-phase arrest and to the induction of DNA damage, ultimately triggering cell death. We reported evidence that the efficacy of the combination treatment is independent from the activation of the p53-p21 pathway. Moreover, gene expression analysis on B-ALL primary samples showed that Chek1 and Wee1 are significantly co-expressed in samples at diagnosis (Pearson r = 0.5770, p = 0.0001) and relapse (Pearson r= 0.8919; p = 0.0001). Finally, the efficacy of the combination was confirmed by the reduction in clonogenic survival of primary leukemic B-ALL cells. Conclusion: Our findings suggest that the combination of CHK1 and WEE1 inhibitors may be a promising therapeutic strategy to be tested in clinical trials for adult ALL.

ARF Loss, a Negative Prognostic Factor in Philadelphia-Positive Acute Lymphoblastic Leukemia, May Be Efficiently Overcome by the Small Molecule MDM2 Antagonist RG7112

Blood ◽  
2011 ◽  
Vol 118 (21) ◽  
pp. 2574-2574
Author(s):  
Ilaria Iacobucci ◽  
Federica Cattina ◽  
Silvia Pomella ◽  
Annalisa Lonetti ◽  
Anna Ferrari ◽  
...  
Keyword(s):  
Cell Cycle ◽  
Acute Lymphoblastic Leukemia ◽  
Cell Viability ◽  
Cell Line ◽  
Cell Lines ◽  
Lymphoblastic Leukemia ◽  
Prognostic Impact ◽  
Wild Type ◽  
Mdm2 Antagonist ◽  
Wild Type P53

Abstract Abstract 2574 Recently, using genome-wide single nucleotide polymorphism arrays and gene candidate deep exon sequencing, we identified lesions in CDKN2A gene, encoding p16/INK4A and p14/ARF tumor suppressors, in 27% (32/117) adult newly diagnosed Philadelphia-positive acute lymphoblastic leukemia (Ph+ ALL) patients and in 47% (14/30) relapsed cases. Clinically, in our cohort CDKN2A deletions were associated by univariate analysis to a worse outcome in terms of overall survival (OS), disease-free survival (DFS) and cumulative incidence of relapse (CIR) (OS: 27.7 vs 38.2 months, p = 0.0206; DFS: 10.1 vs. 56.1 months, p = 0.0010; CIR: 73.3 vs 38.1, p = 0.0014). Noteworthy, the negative prognostic impact of CDKN2A deletion on DFS was also confirmed by the multivariate analysis (p = 0.0051). These results showed that there are genetically distinct Ph+ ALL patients with a different risk of leukemia relapse and that testing for CDKN2A alterations at diagnosis may help in risk stratification. Furthermore, since the loss of CDKN2A eliminates the critical tumor surveillance mechanism and allows proliferation and tumor cell growth by the action of MDM2, a negative regulator of p53, we investigated the preclinical activity of the MDM2 antagonist RG7112 in primary B-ALL patient samples and leukemic cell line models. BV-173, SUPB-15 and K562 Ph+ cell lines were incubated with increasing concentration of RG7112 (0.5–10 μM) and its inactive enantiomer for 24, 48 and 72 hours (hrs). MDM2 inhibition by RG7112 resulted in a dose and time-dependent cytotoxicity with IC50 (24 hrs) of 2 μM for BV-173 and SUPB-15 which harbor homozygous deletion of CDKN2A but wild-type p53. No significant changes in cell viability were observed in K562 p53-null cell line after incubation with RG7112. The time and dose-dependent reduction in cell viability were confirmed in primary blast cells from a Ph+ ALL patient with the T315I Bcr-Abl kinase domain mutation found to be insensitive to the available tyrosine kinase inhibitors and from a t(4;11)-positive ALL patient (IC50 at 24 hrs equal to 2 μM). Consistent with the results of cell viability, Annexin V/Propidium Iodide analysis showed a significant increase in apoptosis after 24 hrs in BV-173, SUPB-15 and in primary leukemia blasts, whereas no apoptosis was observed in K562 cells. To examine the possible mechanisms underlying RG7112-mediated cell death, western blot analysis was performed. Protein levels of p53, p21 (an important mediator of p53-dependent cell cycle arrest), cleaved caspase-3 and caspase-9 proteins increased upon treatment with RG7112 after 24 hrs of incubation with concentrations equal to the IC50. These data demonstrate the ability of RG7112 to activate the intrinsic apoptotic pathway by a p53-dependent mechanism. In order to better elucidate the implications of p53 activation and to identify biomarkers of clinical activity, gene expression profiling analysis (Affymetrix GeneChip Human Gene 1.0 ST) was next performed, comparing sensitive cell lines (BV-173 and SUPB-15) after 24 hrs exposure to 2 μM RG7112 and their untreated counterparts (DMSO 0.1%). A total of 621 genes (48% down-regulated vs 52% up-regulated) were differentially expressed (p < 0.05). They include genes involved in cell cycle and apoptosis control (e.g. Histone H1, TOP2, GAS41, H2AFZ) and in the down-regulation of the Hedgehog signaling (e.g. BMI1, BMP7, CDKN1C, POU3F1, CTNNB1, PTCH2) with a strong repression of stemness genes and re-activation of INK4/ARF as illustrated in Figure 1. Actually, both GAS41 (growth-arrest specific 1 gene) and BMI1 (a polycomb ring-finger oncogene) are repressors of INK4/ARF and p21 and their aberrant expression has found to contribute to stem cell state in tumor cells. In our data they were strongly down-regulated (fold-change −1.35 and −1.11, respectively; p-value 0.02 and 0.03, respectively) after in vitro treatment as compared to control cells, suggesting that these genes have a potential as new biomarkers of activity. In conclusion, inhibition of the p53–MDM2 interaction by RG7112 can activate the p53 pathway, resulting in apoptosis and inhibition of stemness genes in B-ALL with wild-type p53. Our findings provide a strong rational for further clinical investigation of RG7112 in Ph+ ALL. Supported by: ELN, AIL, AIRC, Fondazione Del Monte di Bologna e Ravenna, FIRB 2006, Ateneo RFO grants, Project of integrated program, Programma di Ricerca Regione–Università 2007–2009. Disclosures: Baccarani: Novartis: Consultancy; Bristol Myers Squibb: Consultancy; Novartis: Honoraria; Bristol Myers Squibb: Honoraria; Pfizer: Honoraria; Ariad: Honoraria. Martinelli:Novartis: Consultancy, Honoraria; BMS: Consultancy, Honoraria; Pfizer: Consultancy.

scholarly journals Exploring the ATR-CHK1 pathway in the response of doxorubicin-induced DNA damages in acute lymphoblastic leukemia cells

2021 ◽  
Author(s):  
Andrea Ghelli Luserna Di Rorà ◽  
Martina Ghetti ◽  
Lorenzo Ledda ◽  
Anna Ferrari ◽  
Matteo Bocconcelli ◽  
...  
Keyword(s):  
Cell Cycle ◽  
Acute Lymphoblastic Leukemia ◽  
T Cell ◽  
Cell Lines ◽  
Lymphoblastic Leukemia ◽  
Cell Cycle Checkpoint ◽  
M Cell ◽  
Dna Damages ◽  
Cycle Checkpoint ◽  
Dna Double Helix

AbstractDoxorubicin (Dox) is one of the most commonly used anthracyclines for the treatment of solid and hematological tumors such as B−/T cell acute lymphoblastic leukemia (ALL). Dox compromises topoisomerase II enzyme functionality, thus inducing structural damages during DNA replication and causes direct damages intercalating into DNA double helix. Eukaryotic cells respond to DNA damages by activating the ATM-CHK2 and/or ATR-CHK1 pathway, whose function is to regulate cell cycle progression, to promote damage repair, and to control apoptosis. We evaluated the efficacy of a new drug schedule combining Dox and specific ATR (VE-821) or CHK1 (prexasertib, PX) inhibitors in the treatment of human B−/T cell precursor ALL cell lines and primary ALL leukemic cells. We found that ALL cell lines respond to Dox activating the G2/M cell cycle checkpoint. Exposure of Dox-pretreated ALL cell lines to VE-821 or PX enhanced Dox cytotoxic effect. This phenomenon was associated with the abrogation of the G2/M cell cycle checkpoint with changes in the expression pCDK1 and cyclin B1, and cell entry in mitosis, followed by the induction of apoptosis. Indeed, the inhibition of the G2/M checkpoint led to a significant increment of normal and aberrant mitotic cells, including those showing tripolar spindles, metaphases with lagging chromosomes, and massive chromosomes fragmentation. In conclusion, we found that the ATR-CHK1 pathway is involved in the response to Dox-induced DNA damages and we demonstrated that our new in vitro drug schedule that combines Dox followed by ATR/CHK1 inhibitors can increase Dox cytotoxicity against ALL cells, while using lower drug doses. Graphical abstract • Doxorubicin activates the G2/M cell cycle checkpoint in acute lymphoblastic leukemia (ALL) cells. • ALL cells respond to doxorubicin-induced DNA damages by activating the ATR-CHK1 pathway. • The inhibition of the ATR-CHK1 pathway synergizes with doxorubicin in the induction of cytotoxicity in ALL cells. • The inhibition of ATR-CHK1 pathway induces aberrant chromosome segregation and mitotic spindle defects in doxorubicin-pretreated ALL cells.

scholarly journals Targeted Therapy for ETV6-RUNX1-Driven B-Cell Precursor Acute Lymphoblastic Leukemia

Blood ◽  
2014 ◽  
Vol 124 (21) ◽  
pp. 62-62
Author(s):  
Roel Polak ◽  
Marc B. Bierings ◽  
Cindy S. van der Leije ◽  
Rosanna E.S. van den Dungen ◽  
Mathijs A. Sanders ◽  
...  
Keyword(s):  
Acute Lymphoblastic Leukemia ◽  
Fusion Protein ◽  
Cell Viability ◽  
B Cell ◽  
Cell Survival ◽  
Cell Lines ◽  
Lymphoblastic Leukemia ◽  
Growth Arrest ◽  
Leukemic Cells ◽  
Cell Precursor

Abstract Background: Translocation t(12;21), resulting in the ETV6-RUNX1 fusion protein, is present in 25% of pediatric patients with B-cell precursor acute lymphoblastic leukemia (BCP-ALL). Despite the favorable prognostic parameters of this B-ALL subgroup, relapse and resistance to chemotherapeutics occur and treatment-induced side effects are considerable. The molecular mechanisms underlying ETV6-RUNX1-driven leukemia are largely unknown. Increased knowledge of these mechanisms is essential to develop novel therapeutic strategies to selectively target ETV6-RUNX1-positive leukemia. Objectives: This study aims to identify and target the molecular drivers behind ETV6-RUNX1-positive BCP-ALL. Results: Gene expression profiling of leukemic blasts of 654 ALL patients revealed that the class III PI3-kinase Vps34, an important regulator of autophagy, was exclusively up-regulated in ETV6-RUNX1-positive compared to ETV6-RUNX1-negative BCP-ALL patients (2.7-fold; p ≤ 10-30). In addition, ectopic expression of ETV6-RUNX1 in cord blood-derived hematopoietic progenitor cells (CB-HPCs) significantly induced expression of Vps34 1.3-fold already 40 hours after transduction (p ≤ 0.05). This suggests that the Vps34-autophagy pathway is activated by ETV6-RUNX1, which may mechanistically explain the leukemogenic and pro-survival properties ascribed to ETV6-RUNX1. In correspondence, Ingenuity Pathway Analysis (IPA) predicted a pro-survival and pro-proliferative phenotype in ETV6-RUNX1 transduced CB-HPCs and highlighted a network of up-regulated transcription factors, including HEY1, EGR1, GATA1 and GATA2 (2 – 25-fold up-regulation; p ≤ 0.05). Luciferase reporter assays revealed that not only the ETV6-RUNX1 fusion protein, but also the ETV6-RUNX1-induced target genes HEY1, EGR1 and GATA1 positively regulate Vps34 promoter activity (5 – 13-fold up-regulation; p ≤ 0.01).Lentiviral knockdown experiments were performed to elucidate the importance of Vps34 expression in ETV6-RUNX1-positive BCP-ALL cells. Knockdown of all Vps34 transcript variants, with two independent constructs, led to complete growth arrest of the ETV6-RUNX1-positive cell lines REH and AT2, while this only led to a decrease in proliferation of the ETV6-RUNX1-negative cell line NALM6. This growth arrest was caused by a significant induction of apoptosis (more than 4-fold 7 days after transduction; p ≤ 0.001) and a significantly reduced percentage of cycling cells (1.3-fold 7 days after transduction; p ≤ 0.05). Analysis of p62 protein expression by western blot and reverse phase protein arrays revealed that the levels of autophagy were significantly higher in ETV6-RUNX1-positive compared to ETV6-RUNX1-negative BCP-ALL patients (p ≤ 0.001). In addition, knockdown of ETV6-RUNX1 and Vps34 significantly reduced autophagy, quantified with confocal microscopy, in ETV6-RUNX1-positive cells with 50% and 84%, respectively (p ≤ 0.01). Furthermore, pharmacological inhibition of autophagy with hydroxychloroquine (HCQ) significantly reduced cell viability of BCP-ALL cell lines and primary patient-derived BCP-ALL cells (p ≤ 0.001). Treatment of the ETV6-RUNX1-positive BCP-ALL cell lines REH and AT2 with 20 µg/mL HCQ resulted in a 82% and 95% reduced cell viability, while the viability of ETV6-RUNX1-negative BCP-ALL cell lines and T-ALL cell lines were reduced to a lesser extent (NALM6: 43%; TOM-1: 50%; Loucy: 40%; Jurkat: 0%). Importantly, HCQ selectively sensitized ETV6-RUNX1-positive leukemic cells to L-asparaginase treatment in clinically relevant concentrations. Treatment of primary ETV6-RUNX1-positive patient cells with 10 µg/mL HCQ resulted in a 70% reduction in cell survival during L-asparaginase exposure (p ≤ 0.01). This sensitization was not observed in ETV6-RUNX1-negative BCP-ALL cells. Conclusion: The ETV6-RUNX1 fusion protein activates autophagy via Vps34, which is essential for survival and proliferation of ETV6-RUNX1-positive cells. Inhibition of autophagy in primary ETV6-RUNX1-positive leukemic cells inhibited cell survival and sensitized these cells to L-asparaginase treatment. These results indicate that autophagy inhibition may provide a novel means to sensitize L-asparaginase-resistant ETV6-RUNX1-positive BCP-ALL patients. Disclosures No relevant conflicts of interest to declare.

Effect of Protein Kinase C β Specific Inhibition On Acute Lymphoblastic Leukemia Cell Lines.

Blood ◽  
2009 ◽  
Vol 114 (22) ◽  
pp. 4817-4817
Author(s):  
Nakhle S Saba ◽  
Hana F Safah ◽  
Laura S Levy
Keyword(s):  
Acute Lymphoblastic Leukemia ◽  
Growth Inhibition ◽  
Cell Viability ◽  
B Cell ◽  
Cell Lines ◽  
Chromosomal Abnormality ◽  
Lymphoblastic Leukemia ◽  
Specific Inhibitor ◽  
B Cell Lymphoma ◽  
Specific Inhibition

Abstract Abstract 4817 Acute lymphoblastic leukemia (ALL) is the most common leukemia in children and accounts for 20% of acute leukemia in adults. The intensive induction–consolidation–maintenance therapeutic regimens used currently have improved the 5-year disease free survival to around 80% in children and to 25%-40% in adults. The poorer response in adults is basically due to the inability to tolerate the intensive chemotherapy, and to the biology of adult disease which is associated with poor-risk prognostic factors. In the present era of target-specific therapy, PKCβ targeting arose as a new, promising, and well tolerated treatment strategy in a variety of neoplasms, especially in B-cell malignancies. It showed encouraging results in preclinical and clinical studies involving chronic lymphocytic leukemia, diffuse large B-cell lymphoma and multiple myeloma. PKCβ plays a major role in B-cell receptor signaling, but studies describing the role of PKCβ in B-cell ALL are lacking. In the present study, we measured the sensitivity of a variety of B-cell ALL cell lines to PKCβ specific inhibition. Three cell lines were studied: RS4;11 (characterized by the t(4;11) chromosomal abnormality), TOM-1 (characterized by the t(9;22) chromosomal abnormality), and REH (characterized by the t(12;21) chromosomal abnormality). Cells were tested for PKCβ1 and PKCβ2 expression by immunoblot. Cell viability was measured when PKCβ-specific inhibitor at concentrations of 1, 2.5, 5, 10, 20 and 30 μM was added for 48 hours in the presence of 10% fetal bovine serum (FBS). MTS assay was performed to quantify cell viability. Results showed that all three cell lines express PKCβ1 and PKCβ2. Treatment with PKCβ-specific inhibitor resulted in a dose-dependent inhibition of cell proliferation; Sensitivity was evident at 1 μM for RS4;11 cell line, and at 2.5 μM for TOM-1 and REH cell lines, with 10% cell growth inhibition; Growth inhibition increased to 90% for all cell lines at an inhibitor concentration of 30 μM. These results indicate that PKCβ plays an important role in the malignant process in B-cell ALL, and suggest that PKCβ targeting should be considered as a potential treatment, whether in combination with the current regimens used or as a single agent monotherapy. Ongoing studies in our lab will detail the mechanism of PKCβ and adverse cytogenetics like t(4;11) and t(9;22). Disclosures: No relevant conflicts of interest to declare.

Disrupting NEDD8-Mediated Protein Turnover with MLN4924 Significantly Augments the Efficacy of Cytarabine

Blood ◽  
2010 ◽  
Vol 116 (21) ◽  
pp. 3255-3255
Author(s):  
Steffan T Nawrocki ◽  
Kevin R Kelly ◽  
Kelli Oberheu ◽  
Devalingam Mahalingam ◽  
Peter G Smith ◽  
...  
Keyword(s):  
Cell Cycle ◽  
Signal Transduction ◽  
Dna Damage ◽  
Elderly Patients ◽  
Cell Viability ◽  
Cell Lines ◽  
Protein Turnover ◽  
Cell Cycle Progression ◽  
Clonogenic Survival ◽  
Cycle Progression

Abstract Abstract 3255 Cytarabine-based therapy has been utilized in acute myeloid leukemia (AML) therapy for more than 30 years. However, the complete response (CR) rates are markedly inferior in older compared to younger patients with AML (45% versus 75%, respectively) due, in part, to the reduced ability of elderly patients to tolerate intensive therapy. Improving the outcomes for patients treated with cytarabine-based regimens represents a major clinical challenge in this disease. A randomized study of elderly patients with AML demonstrated that low dose cytarabine (LDAC) is superior to best supportive care. However, this regimen was not associated with any CRs in patients with adverse karyotype disease and/or poor baseline performance scores. Novel approaches are urgently needed to increase the efficacy of LDAC therapy for these patients. Timed protein destruction plays a crucial role in cellular homeostasis and is essential for many critical functions including cell cycle progression, signal transduction, and apoptosis. The processes that govern protein degradation frequently become dysregulated in cancer cells. Aberrant protein turnover contributes to disease progression, metastasis, and therapeutic resistance and therefore is an attractive target for selective pharmacological inhibition. The cullin-RING ubiquitin ligases (CRLs) are a subset of E3 ubiquitin ligases whose activity is regulated by modification with the ubiquitin-like molecule NEDD8. The CRLs control the ubiquitination and subsequent degradation of many proteins with important roles in cell cycle progression, DNA damage, stress responses, and signal transduction. MLN4924 is a potent and selective small molecule inhibitor of NEDD8 activating enzyme (NAE), the proximal regulator of the NEDD8 conjugation pathway, and has entered Phase I clinical trials for AML and other forms of cancer. Our earlier preclinical studies demonstrated that MLN4924 induced cell death in AML cell lines and primary patient specimens independent of FLT3 expression and stromal-mediated survival signaling and led to the stabilization of key NAE targets, inhibition of NF-kB activity, DNA damage, and reactive oxygen species generation. Notably, administration of MLN4924 to mice bearing AML xenografts was very well tolerated, led to stable disease regression and inhibition of NEDDylated cullins. Based on the high tolerability, potency, and multifaceted mechanism of action of MLN4924, we hypothesized that it may significantly augment the efficacy of the standard agent cytarabine. To test our hypothesis, we first investigated the effects of this therapeutic combination on cell viability, clonogenic survival, and apoptosis induction in a panel of AML cell lines. MLN4924 cooperated with cytarabine to significantly reduce cell viability, inhibit clonogenic survival, and induce mitochondrial-dependent apoptosis. The addition of MLN4924 did not significantly alter the sensitivity of normal peripheral blood mononuclear cells from healthy donors to cytarabine, indicating that this combination may have therapeutic selectivity. Immunoblotting analyses revealed that MLN4924 enhanced cytarabine-induced stabilization of the NEDD8 target and cell cycle regulator, p27. The MLN4924/cytarabine combination also promoted increased phosphorylation of the DNA damage response regulator Chk1. Targeted knockdown of Chk1 demonstrated a critical role for Chk1 as a mediator of the pro-apoptotic effects of this combination. In vivo examining the combination is in progress and will be presented. Our collective findings suggest that combining the novel NAE inhibitor MLN4924 with cytarabine is a promising strategy for AML therapy that warrants further investigation. Disclosures: Smith: Millennium Pharmaceuticals, Inc.: Employment.

Quantitative Proteomic Analysis Reveals Maturation As a Mechanism Underlying Glucocorticoid Resistance in Childhood Acute Lymphoblastic Leukemia and PAX5 As a Re-Sensitising Therapeutic Target

Blood ◽  
2011 ◽  
Vol 118 (21) ◽  
pp. 1411-1411
Author(s):  
Lindsay Nicholson ◽  
Caroline Evans ◽  
Elizabeth C Matheson ◽  
Lynne Minto ◽  
Christopher Keilty ◽  
...  
Keyword(s):  
Acute Lymphoblastic Leukemia ◽  
Cell Viability ◽  
B Cell ◽  
Cell Line ◽  
Cell Lines ◽  
Therapeutic Target ◽  
Proteomic Analysis ◽  
Lymphoblastic Leukemia ◽  
Childhood All ◽  
Resistant Phenotype

Abstract Abstract 1411 Glucocorticoids (GC), such as prednisolone and dexamethasone, are an integral component of the multi-agent treatment of childhood acute lymphoblastic leukemia (ALL). GC-resistance is a significant prognostic indicator of a poor treatment outcome and remains a clinical problem, with the underlying mechanisms still unclear. Mutation or loss of the primary mediator of GC-action, the glucocorticoid receptor (GR), underlies the GC-resistant phenotype in several commonly used leukemic cell lines. However, these events are rare in primary leukemic cells, with relatively few examples in vivo. This suggests that it may be possible to reverse the GC-resistant phenotype pharmacologically. We have used an iTRAQ proteomics approach for hypothesis generation of potential mechanisms for GC-resistance in childhood ALL. To achieve this, we compared a well-characterized GC-sensitive cell line, PreB 697, and a GC-resistant sub-clone (R3F9), both bearing wildtype GR, in a comparative proteomic experiment using 4-channel isobaric tagging for relative and absolute quantification (iTRAQ). A comparison of protein profiles before and after dexamethasone exposure of the two cell lines identified two transcription factors involved in B-cell differentiation, PAX5 and IRF4, to be differentially upregulated in the PreB 697 compared to the R3F9 cell line in response to GC. Experimentally, there was approximately 50% reduction in PAX5 basal protein expression in R3F9 compared to its GC-sensitive parent, a finding which was also evident in four other resistant sub-lines. This was accompanied by a decreased expression of CD19 and CD10, indicative of an increased B-cell maturation state. The reduced PAX5 level in the GC-resistant cell lines was not due to mono-allelic loss or mutation and mRNA levels were not significantly altered, suggestive of a post-transcriptional mechanism for PAX5 protein reduction. Paradoxically, knockdown of PAX5 reversed the GC-resistant phenotype of the R3F9 cell line such that the apoptotic response to dexamethasone was similar to that of the GC-sensitive parent line as measured by Annexin V staining (R3F9: mean 52.22%, SD 12.54%, n=3; PreB 697: mean 67.23%, SD 9.96%, n=3) and cell viability assays. This chemosensitization after PAX5 knockdown was specific to GC, with no difference in cell viability observed in either cell line after exposure to daunorubicin, vincristine or L-asparaginase when compared to negative siRNA or mock controls. This increase in GC-sensitivity was coupled with a significant upregulation of GR and its transcriptional target, GILZ. We also showed an enhanced GC response after PAX5 knockdown in two out of eight primary, diagnostic pre-B lineage ALL patient samples. Thus, in this ALL cell line model, quantitative proteomic analysis revealed increased maturation as a recurrent mechanism underlying GC-resistance and identifies PAX5 as a possible therapeutic target to fully re-sensitise GC-response in childhood ALL. Disclosures: No relevant conflicts of interest to declare.

In Vitro Effects of PI3Kδ Inhibitor GS-1101 (Cal-101) in Acute Lymphoblastic Leukemia (ALL)

Blood ◽  
2012 ◽  
Vol 120 (21) ◽  
pp. 3534-3534 ◽  
Author(s):  
Nathalie Y Rosin ◽  
Stefan Koehrer ◽  
Ekaterina Kim ◽  
Susan O'Brien ◽  
William G. Wierda ◽  
...  
Keyword(s):  
Cell Cycle ◽  
Acute Lymphoblastic Leukemia ◽  
Cell Growth ◽  
B Cell ◽  
Cell Lines ◽  
Lymphoblastic Leukemia ◽  
Lymphocytic Leukemia ◽  
P Value ◽  
B Cell Malignancies ◽  
Growth Experiments

Abstract Abstract 3534 Acute lymphoblastic leukemia (ALL) is a highly heterogeneous disease. B-cell acute lymphoblastic leukemia (B-ALL) is characterized by uncontrolled proliferation of immature lymphoid blasts with suppression of normal hematopoiesis. Phosphoinositide 3-kinases (PI3K) transmit activation signals from diverse transmembrane receptors, leading to generation of phosphatidylinositol- 3,4,5-trisphosphate (PIP3) which promotes proliferation, differentiation, migration, and survival in lymphocytes and various other cell types. A knockout mouse model of the PI3K isoform p110δ demonstrates a unique role of p110δ (PI3Kδ) in B cell receptor (BCR) signaling. This is corroborated by clinical efficacy of the PI3Kδ inhibitor GS-1101 in mature B cell malignancies, especially in chronic lymphocytic leukemia (CLL). In contrast to mature B cell malignancies, expression and function of PI3Kδ in B-ALL has not been well characterized. We therefore analyzed PI3Kδ expression and effects of the PI3Kδ inhibitor GS-1101 in B-ALL. To screen efficacy of GS-1101 in B-ALL subsets, we performed viability and proliferation assays, using a panel of B-ALL cell lines, derived from different B-cell development stages (Pro-B: REH, RS4;11, Nalm-20, Nalm-21, TOM-1; Pre-B: Nalm-6, Kasumi-2, KOPN-8, SMS-SB, RCH-ACV, 697; Mature: Tanoue, Ball-1 unknown: CCRF-SB). A key downstream effector of PI3K is the serine/threonine kinase Akt, whose phosphorylation is used as a common readout of PI3K activation status. Western Blot analysis of the 15 cell lines showed almost identical levels of phospho-Akt (Ser473) in all tested cell lines, suggesting constitutive PI3K activity. To investigate the ability of GS-1101 to inhibit B-ALL cell proliferation, we performed cell growth experiments. Among the pre-B cell lines 4 of 6 showed a marked decrease in proliferation, 2 other pre-B cell lines showed a minor decrease. In contrast, none of the pro-B or mature B-ALL cell lines were affected by GS-1101. To explore the effects of GS-1101 on cell cycle of B-ALL cells, cell lines were treated with GS-1101 at concentrations ranging from 0.5μM to 5μM. In accordance with the cell growth experiments, G1 phase arrest and reduced numbers of S phase cells were detected in pre-B cell lines after GS-1101 treatment, but not in the pro-B or mature B cell lines. Next, we examined GS-1101 effects on metabolism of B-ALL cells via XTT (sodium 2,3,-bis(2-methoxy-4-nitro-5-sulfophenyl)-5-[(phenylamino)-carbonyl]-2H-tetrazolium inner salt) staining. Cell lines were treated with GS-1101 concentrations between 0.1μM and 5μM for 3 days prior to XTT measurement. Pre-B cells showed a significant (p-value <0.0001) decrease in normalized absorbance compared to the control (without treatment) indicating a decrease in cellular viability. Finally, preliminary co-culture experiments of primary B-ALL samples and KUSA-H1 bone marrow stromal cells revealed significantly reduced B-ALL cell viability after GS-1101 treatment, signifying that GS-1101 can overcome microenviromental-mediated B-ALL cell protection; this is similar to that in other B cell malignances. In summary, these experiments demonstrate that GS-1101 inhibits growth, cell cycle progression and metabolic activity of pre-B ALL cells. Validation of these data with primary patient samples is ongoing. Disclosures: Lannutti: Gilead Sciences Inc: Employment.

PI3K/Akt/mTOR Pathway Inhibition in Chemotherapy-Sensitive and -Resistant Models of Burkitt Lymphoma

Blood ◽  
2015 ◽  
Vol 126 (23) ◽  
pp. 1558-1558 ◽  
Author(s):  
Maria Bhatti ◽  
Thomas Ippolito ◽  
Cory Mavis ◽  
Matthew J. Barth
Keyword(s):  
Cell Cycle ◽  
Flow Cytometry ◽  
Cell Viability ◽  
Cell Line ◽  
Cell Lines ◽  
Propidium Iodide ◽  
Mtor Pathway ◽  
Propidium Iodide Staining ◽  
Induction Of Apoptosis ◽  
Pre Treatment

Abstract Introduction: Burkitt lymphoma (BL) is the most common form of B-cell non-Hodgkin lymphoma (B-NHL) in children. Despite significant improvements in survival with de novo disease, treatment of relapsed or refractory BL remains a significant hurdle with survival in only about 20% of patients. Novel therapeutic approaches are necessary to improve outcomes in this group of childhood B-NHL patients with the worst prognosis. Recent literature has identified a high rate of recurrent mutations that result in activation of the PI3K/Akt pathway in BL and have implicated activation of PI3K/Akt in coordination with Myc in BL lymphomagenesis. Our laboratory has developed rituximab and chemotherapy resistant cell line models and subsequently found that these cell lines exhibit increased activation of Akt. We hypothesized that increased activation of Akt may be contributing to chemoresistance and that targeting the PI3K/Akt/mTOR pathway may increase chemoresponsiveness. To that end, we have investigated the effect of inhibiting the PI3K/Akt/mTOR pathway with either the PI3K-delta inhibitor idelalisib or the pan-PI3K/mTOR inhibitor BEZ-235 in cell line models of BL. Methods: The in vitro effect of idelalisib or BEZ-235 was investigated in BL cell lines including Raji, Raji 2R and Raji 4RH (rituximab-chemotherapy resistant), Raji 7R and Raji 8RH (rituximab resistant), Ramos and Daudi. Cell viability following inhibitor exposure was assessed by Alamar blu and cell-titer glo assays. The effect of inhibitor exposure on cell cycle progression was determined by flow cytometry using propidium iodide staining. Inhibition of Akt activation following inhibitor exposure was determined using phospho-flow cytometry. The activity of cytotoxic chemotherapeutic agents following inhibition by idelalisib or BEZ-235 was assessed using Alamar blu and cell titer glo assays. Results: In vitro exposure of BL cell lines to idelalisib in concentrations from 0.1-100µM for 24, 48 or 72 hours resulted in a dose and time-dependent decrease in viable cells in all cell lines tested with IC50 concentrations of 60-300uM. Pre-treatment with the pan-caspase inhibitor QVD resulted in a small reversal in the decrease in cell viability suggesting only a minimal portion of the activity was caspase dependent. When induction of apoptosis was measured using annexin V-propidium iodide staining, little induction of apoptosis was observed with single agent idelalisib at concentrations up to 100uM. Determination of cell cycle progression following exposure to idelalisib at 1, 10, 50 or 100 uM for 24, 48 or 72 hours indicated a time and dose dependent cell cycle arrest in all cell lines. In chemotherapy-sensitive cell lines the arrest was primarily noted in G1, while the chemotherapy-resistant Raji 2R and Raji 4RH cell lines exhibited arrest primarily in G2/M. A significant reduction in cell viability following chemotherapy exposure for 48 hours was noted in chemotherapy resistant Raji 2R cells following pre-treatment for 48 hours with idelalisib 10uM compared to non-idelalisib exposed cells (doxorubicin 10uM 55% vs 77%, p<0.001; vincristine 0.05uM, 48% vs 61%, P<0.001). At higher idelalisib pre-treatment concentrations (50uM) additional synergistic activity was observed in Raji 2R cells (cisplatin 48% vs 61%, p<0.001; dexamethasone 67% vs 87%, p<0.01). To further assess the effect of dual inhibition of PI3K and mTOR, cell lines were exposed to the dual inhibitor BEZ-235. BEZ-235 exhibited a more potent decrease in cell viability compared to idelalisib with activity at nM concentrations. Unlike idelalisib, exposure to BEZ-235 resulted in significant induction of apoptosis by Annexin V-propidium iodide staining. BEZ-235 also exhibited synergistic activity in combination with chemotherapy in all cell lines. At equivalent dosing, BEZ-235 exposure resulted in a more significant decrease in Akt phosphorylation compared to idelalisib as determined by flow cytometry for p-Akt at Ser and Thr phosphorylation sites. Conclusions: Chemotherapy sensitive and resistant BL cell line models are susceptible to inhibition of the PI3K/Akt/mTOR pathway. Targeted inhibition of this pathway leads to a decrease in AKT activation, decrease in cell viability, cell cycle arrest and an increase in sensitivity to cytotoxic chemotherapeutic agents. Broader inhibition of both PI3K and mTOR is more effective than more targeted inhibition of PI3K-delta alone. Disclosures No relevant conflicts of interest to declare.

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