FLT3-ITD+ AML Blast, Progenitor and Stem Cell Populations Demonstrate Higher Sensitivity to the Hsp90 Inhibitor PU-H71,

Blood ◽  
2011 ◽  
Vol 118 (21) ◽  
pp. 3500-3500
Author(s):  
Hongliang Zong ◽  
Tony Taldone ◽  
James H. Ahn ◽  
Sarah Brennan ◽  
Jeanne P. De Leon ◽  
...  
Keyword(s):  
Stem Cells ◽  
Cell Lines ◽  
Leukemia Cell ◽  
Hsp90 Inhibitor ◽  
Cell Populations ◽  
Wild Type ◽  
Hsp90 Inhibition ◽  
Leukemia Cell Lines ◽  
Client Proteins ◽  
Higher Sensitivity

Abstract Abstract 3500 Hsp90, one of the best-characterized molecular chaperones, plays indispensable roles in folding and assembly, intracellular transport, stabilization, and degradation of proteins, and therefore, facilitating cell signaling. Hsp90 is also involved in tumorigenesis by stabilizing oncogenic client proteins. Thus, Hsp90 inhibition has been considered a promising therapeutic strategy for different types of cancer including leukemia. PU-H71 is a novel HSP90 inhibitor with high specificity for oncogenic Hsp90. We investigated the effect of PU-H71 in acute myelogenous leukemia (AML), in particularly, AML stem cells (AML-SCs) that are known to give rise to AML blasts, are refractory to conventional therapies, and thus likely to account for AML relapses. The effect of PU-H71 was evaluated using a panel of 12 leukemia cell lines. Among the 12 leukemia cell lines tested, MOLM-13 and MV4-11 cells were the most sensitive (LD50s 253 nM and 120 nM respectively). Both MV4-11 and MOLM-13 carry FLT3-ITD mutation (occurring in ∼40% AML cases) and MLL translocations (occurring in ∼20% AML cases). Both MLL and FLT3 have been reported as client proteins of Hsp90. However, other leukemia cell lines with MLL rearrangements such as THP-1 and a MLL-ENL cell line derived from MLL-ENL transformed human CD34+ cord blood cells exhibited resistance to PU-H71 treatment (LD50 > 2 μM). The data suggested that FLT3-ITD+ AML samples may display higher sensitivity to Hsp90 inhibition. To confirm the higher sensitivity of FLT3-ITD+ AML cells to Hsp90 targeted therapy, 15 primary AML patient samples (8 FLT3-ITD mutants and 7 wild type FLT3) were treated with increasing concentrations of PU-H71. Cell viability on different cell populations was evaluated using multiparameter flow cytometry at 48 hours after treatment with PU-H71. The average LD50 of PU-H71 in FLT3-ITD+ AML cells was 492 nM (95% CI, 127.636 – 856.364). In contrast, the average LD50 in AML samples with wild type FLT3 was 2.795 μM (95% CI, 1.058 – 4.532). The near 6-fold difference between LD50s for PU-H71 was significant (p=0.0068). Importantly PU-H71 also killed FLT3-ITD+ AML stem and progenitor cells more effectively. Furthermore, PU-H71 treatment decreased the ability to form colonies in FLT3-ITD+ AML specimens more effectively than FLT3 WT AMLs (97.6% and 79.3% decrease relative to control respectively; N=3; P=0.0236). Importantly, PU-H71 had minor toxicity to normal blood mononuclear cells and normal cord blood hematopoietic stem cells. FLT3-ITD+ cell lines and primary AML cells treated with 0.5 μM PU-H71 showed a substantial decrease of phosphorylated forms of Erk1/2, JNK, AKT, p70RSK, NF-κB(p65) and Stat5, which was observed within 4 hours post PU-H71 treatment, whereas the phosphorylation levels of MAPK p38 remained unaffected. Immunoblotting and phosphoflow assays corroborated the inhibition of AKT and Stat5 signaling by PU-H71 in stem and progenitor populations. In summary, FLT3-ITD+ AML cells display a stronger response to PU-H71, suggesting that the FLT3-ITD mutation results in a higher dependency on Hsp90 to stabilize the aberrant signaling elicited by constitutive activation of FLT3. Our data suggests that PU-H71 represents a novel therapy for FLT3-ITD+ AML patients with the potential to ablate AML-SCs. Disclosures: Roboz: EpiCept: Consultancy; ChemGenex: Consultancy; Celgene: Consultancy; Boehringer Ingelheim: Consultancy.

A Functional Wild-Type p53 Gene Is Expressed in Human Acute Myeloid Leukemia Cell Lines

Blood ◽  
1998 ◽  
Vol 92 (8) ◽  
pp. 2977-2979 ◽  
Author(s):  
Trenna Sutcliffe ◽  
Loning Fu ◽  
Jacinth Abraham ◽  
Homayoun Vaziri ◽  
Samuel Benchimol
Keyword(s):  
Acute Myeloid Leukemia ◽  
Cell Lines ◽  
Myeloid Leukemia ◽  
Leukemia Cell ◽  
P53 Gene ◽  
Wild Type ◽  
Leukemia Cell Lines ◽  
Human Acute Myeloid Leukemia ◽  
Acute Myeloid ◽  
Myeloid Leukemia Cell

The Novel Sulfonamidebenzamide ML291 Activates Apoptotic UPR Signaling in Pediatric Leukemia

Blood ◽  
2016 ◽  
Vol 128 (22) ◽  
pp. 3523-3523
Author(s):  
Danielle Garshott ◽  
Nicole Melong ◽  
Tania T. Sarker ◽  
Yue Xi ◽  
Amy Brownell ◽  
...  
Keyword(s):  
Cell Lines ◽  
Leukemia Cell ◽  
Leukemic Cell ◽  
K562 Cells ◽  
Leukemia Cells ◽  
Wild Type ◽  
Leukemia Cell Lines ◽  
Proliferation Assays

Abstract Background: Acute leukemias are the most common cancers in childhood. Despite multi-agent chemotherapy protocols and the introduction of novel molecularly targeted therapies which have resulted in improved survival over the last few decades, relapsed acute lymphoblastic leukemia remains the second most common pediatric cancer diagnosis. In addition, morbidities from current chemotherapy regimens are unacceptably high. Abundant evidence point to a major role for mediators of the unfolded protein response (UPR) in normal and leukemic white blood cell biology. We have demonstrated that activation of the UPR is a productive approach to inhibit the proliferation of solid tumor cell lines in vitro and to reducing xenograft burden in vivo. The UPR consists of genetically distinct mechanisms that serve to clear misfolded proteins from the endoplasmic reticulum (ER) and enhance protein folding, or induce apoptosis if the initiating stress is prolonged or robust. ML291 is a novel UPR-inducing sulfonamidebenzamide, identified through cell-based high throughput screening and iterative SAR-guided chemical synthesis, that overwhelms the adaptive capacity of the UPR and induces apoptosis in a variety of solid cancer models. Objective: To determine the ability of ML291 to activate the UPR and induce apoptosis in a panel of leukemia cell lines, and to use CHOP-null K562 cells to elucidate the relative contribution of the UPR. We hypothesized that ML291 might activate the PERK/eIF2a/CHOP (apoptotic) arm of the UPR and reduce leukemic cell burden in vitro and in vivo. Methods: MTT and luciferase-based proliferation assays, flow cytometry and RT-qPCR were used to evaluate cell growth, UPR activation and apoptosis in a panel of leukemia cell lines that included AML, ALL and CML in cells exposed to ML291. CRISPR-Cas9 genome editing was used to delete CHOP in K562 (human myeloid leukemia) cells. Deletion was validated by immunoblot analysis and these cells were subjected to the same proliferation and gene analyses described above. The in vivo response to ML291 therapy was evaluated in an established zebrafish xenograft assay (Corkery et al. BJH 2011) in which embryos were xenotransplanted with wild type or CHOP knockdown K562 cells and embryos bathed in ML291. Results: Immunoblot and RT-qPCR analysis revealed an accumulation of proteins and increased gene expression for downstream UPR genes, including CHOP, GRP78/BiP, GADD34 and XBP1 in leukemia cells following ML291 treatment, indicating the activation of the UPR. Increased expression of the apoptotic genes, NOXA, PUMA and DR5 was also observed post-treatment with ML291; and dose response proliferation assays performed after 24 hours revealed IC50 concentrations of 1 - 30µM across cell lines. CHOP deleted K562 cells were protected from cell death when cultured with increasing concentrations of ML291, and were significantly less able to translocate phosphatidylserine across the cell membrane and activate the caspase cascade. When zebrafish embryos xenotransplanted with K562-wild type or -CHOP-null cells were bathed in water containing 5mM ML291 for three days, there was a significant reduction in leukemia cell burden exclusively in theK562 wild type xenografts. Conclusion: Collectively these data indicate that intact PERK/eIF2a/CHOP signaling is required for efficient leukemic cell apoptosis in response to ML291 in vitro and in vivo, and support the hypothesis that small molecule enforcement of the UPR might be a productive therapeutic approach in leukemia. Disclosures No relevant conflicts of interest to declare.

scholarly journals Hsp90-inhibitor geldanamycin abrogates G2 arrest in p53-negative leukemia cell lines through the depletion of Chk1

Oncogene ◽  
2007 ◽  
Vol 27 (22) ◽  
pp. 3091-3101 ◽  
Author(s):  
K Sugimoto ◽  
M Sasaki ◽  
Y Isobe ◽  
M Tsutsui ◽  
H Suto ◽  
...  
Keyword(s):  
Cell Lines ◽  
Leukemia Cell ◽  
Hsp90 Inhibitor ◽  
G2 Arrest ◽  
Leukemia Cell Lines

scholarly journals Inhibition of growth of human leukemia cell lines by retrovirally expressed wild-type p16INK4A

Leukemia ◽  
1997 ◽  
Vol 11 (10) ◽  
pp. 1673-1680 ◽  
Author(s):  
AF Gombart ◽  
R Yang ◽  
MJ Campbell ◽  
JD Berman ◽  
HP Koeffler
Keyword(s):  
Cell Lines ◽  
Leukemia Cell ◽  
Human Leukemia ◽  
Wild Type ◽  
Human Leukemia Cell ◽  
Inhibition Of Growth ◽  
Leukemia Cell Lines

DOCK2 Interacts with FLT3 and Modulates the Survival of FLT3-Expressing Leukemia Cells

Blood ◽  
2014 ◽  
Vol 124 (21) ◽  
pp. 3584-3584
Author(s):  
Min Wu ◽  
Max Hamaker ◽  
Li Li ◽  
Donald Small ◽  
Amy S. Duffield
Keyword(s):  
Cell Lines ◽  
Conflicts Of Interest ◽  
Receptor Gene ◽  
Leukemia Cell ◽  
Leukemia Cells ◽  
Wild Type ◽  
Knock Down ◽  
Leukemia Cell Lines ◽  
Significant Difference ◽  
Flt3 Expression

Abstract The FMS-like tyrosine kinase-3 (FLT3) receptor gene is the most commonly mutated gene in acute myeloid leukemia (AML), and patients carrying FLT3/ITD mutations have a poor prognosis. Despite continuing progress in the development of more effective FLT3 inhibitors, long-term success in inhibition of FLT3 activity in AML patients is still elusive. In order to achieve a better understanding of FLT3 biology and more effective strategies for the inhibition of FLT3 activity, a screen was performed on leukemia cell lines to search for FLT3-interacting proteins. One of the proteins identified in the screen was dedicator of cytokinesis 2 (DOCK2). The DOCK family of proteins acts as guanine nucleotide exchange factors (GEFs) for Rho family of GTPases, which includes Rac GTPases. DOCK2 expression is limited to hematopoietic cells, and is known to regulate several crucial processes, including lymphocyte migration, activation and differentiation of T cells, and cell-cell adhesion and bone marrow homing of various immune cells. We first verified that DOCK2 is expressed in primary AML samples from patients, and co-immunoprecipitation experiments showed that DOCK2 interacts with both wild-type FLT3 and FTL3/ITD in these cells. Co-immunoprecipitation experiments using leukemia cell lines demonstrated that DOCK2 interacts with FLT3, FLT3/ITD, FLT3/D835Y and FLT3/D835H, and that it predominantly interacts with the unphosphorylated form of FLT3. Knock-down of DOCK2 by shRNA did not significantly affect the growth of cell lines that lack expression of FLT3, but greatly reduced growth of cell lines expressing amplified wild type FLT3 (Sem K2), FLT3/D835H (HB11;19) and FLT3/ITD (MV4;11). Accordingly, colony formation assays revealed that cell lines with elevated expression of wild type or mutant FLT3 produced fewer, smaller and more compact colonies when the expression of DOCK2 was decreased, while colonies from cell lines lacking FLT3 expression showed no significant difference in response to the knock-down of DOCK2. Furthermore, an Annexin V binding assay indicated that reduction in DOCK2 expression level greatly sensitized cells with elevated FLT3 activity (MV4;11 and Sem K2) to cytarabine, resulting in increased apoptosis, but no significant sensitization was observed in cell lines that lack FLT3 expression. These findings demonstrate that DOCK2 interacts with FLT3 in leukemia cell lines, and suggest that this interaction has important roles in regulating the survival of leukemia cells with elevated FLT3 activity, both alone and in combination with conventional anti-leukemic agents. Therefore, DOCK2 is a potential therapeutic target for AML treatment, and better understanding of the interaction between DOCK2 and FLT3 may contribute to the development of novel strategies to effectively inhibit FLT3 activity in AML patients. Disclosures No relevant conflicts of interest to declare.

scholarly journals Frequent mutations in the p53 gene in human myeloid leukemia cell lines

Blood ◽  
1992 ◽  
Vol 79 (9) ◽  
pp. 2378-2383 ◽  
Author(s):  
K Sugimoto ◽  
H Toyoshima ◽  
R Sakai ◽  
K Miyagawa ◽  
K Hagiwara ◽  
...  
Keyword(s):  
Cell Lines ◽  
Myeloid Leukemia ◽  
Direct Sequencing ◽  
Leukemia Cell ◽  
P53 Gene ◽  
Wild Type ◽  
Rt Pcr ◽  
Leukemia Cell Lines ◽  
Myeloid Leukemia Cell ◽  
P53 Mrna

Abstract The p53 gene is currently considered to function as a tumor-suppressor gene in various human malignancies. In hematologic malignancies, alterations in the p53 gene have been shown in some human leukemias and lymphomas. Although mutations in the p53 gene are infrequent in acute myelogenous leukemia (AML) patients, we show in this report that alterations in the p53 gene are frequent in myeloid leukemia cell lines. We studied alterations of the p53 gene in nine human myeloid leukemia cell lines by reverse transcriptase-polymerase chain reaction (RT-PCR), single-strand conformation polymorphism (SSCP) analysis, and direct sequencing. Expression of the p53 gene was not detected at all by RT-PCR in two of the nine cell lines. In these two cell lines, Southern blot analysis showed gross rearrangements and deletions in both of the p53 alleles. Six of the nine cell lines were found to express only mutant p53 mRNA by RT-PCR/SSCP analysis and direct sequencing, and wild-type p53 mRNA was not detected. Two of the mutant p53 mRNAs were shown to be products of abnormal splicing events induced by intronic point mutations. Taken together, eight of nine human myeloid leukemia cell lines expressed no or an undetectable amount of wild-type p53 mRNA. Three of the eight cell lines were growth factor- dependent. Our results suggest that inactivation of the p53 gene may be a common feature in myeloid leukemia cell lines and may play an important role in the establishment of these cell lines.

Natural-Based Indirubins Display Potent Cytotoxicity toward Wild-Type and T315I-Resistant Leukemia Cell Lines

2016 ◽  
Vol 79 (10) ◽  
pp. 2464-2471 ◽  
Author(s):  
Nicolas Gaboriaud-Kolar ◽  
Vasillios Myrianthopoulos ◽  
Konstantina Vougogiannopoulou ◽  
Panagiotis Gerolymatos ◽  
David A. Horne ◽  
...  
Keyword(s):  
Cell Lines ◽  
Leukemia Cell ◽  
Wild Type ◽  
Leukemia Cell Lines

Molecular Mechanisms of Cell Density-Dependent Growth in Myeloid and Lymphoid Leukemia Cell Lines.

Blood ◽  
2007 ◽  
Vol 110 (11) ◽  
pp. 4122-4122
Author(s):  
Ikuo Murohashi ◽  
Noriko Ihara
Keyword(s):  
Stem Cells ◽  
Cell Lines ◽  
Leukemia Cell ◽  
Cell Number ◽  
Leukemia Cells ◽  
Lymphoid Leukemia ◽  
Hematopoietic Stem ◽  
Cultured Cell ◽  
Leukemia Cell Lines ◽  
Cell Densities

Abstract Normal hematopoietic stem cells have been shown to be maintained through interaction with their environmental niches, such as osteoblastic and endothelial ones. The growth of leukemia cells has been shown to be stimulated by environmental niches (paracrine growth) or by cell-to-cell interaction and/or excreted factors of leukemia cells (autocrine growth). The growth of myeloid (MO7-E and HL-60) and lymphoid (Raji, U-266, Daudi and RPMI-1788) leukemia cell lines cultured at various cell densities in serum free medium (Sigma H 4281) with 1% BSA was evaluated. The cells cultured at higher cell densities (cultured cell densities of more than 105/ml) showed logarithmic linear increases in cell number, whereas those at lower cell densities (cultured cell densities of less than 104/ml) ceased increasing cell number. Supernatants of myeloid leukemia cells stimulated the growth of autologous clonogenic cells, but not those of lymphoid leukemia cells. Neutralizing antibodies (Abs) against various hematopoietic growth factors failed to inhibit cell growth except for anti-VEGF Ab, which significantly decreased HL-60 leukemia cell growth. In contrast, anti-TNF-α Ab significantly stimulated the growth of the HL-60 cells. To clarify the nature of the cultured cell density on the growth of leukemia cells, leukemia cells were cultured at higher cell densities (group H, cultured cell densities of 106/ml) or at lower cell densities (group L, cultured cell densities of 104/ml). After culture of 3-, 6-, 10-, and 24-hr, cells were serially harvested and total cellular RNA was extracted. Gene transcript levels were determined by using Real-Time PCR. Gene transcripts examined in the present study were as follows: Jagged-1, -1, Notch-1, -2, -3, Ang-1, -2, Tie-1, -2, Wnd3a, Wnd5a, β-Catenin, γ-Catenin, N-Cadherin, Cyclin D1, p16, p21, HOXA6, HOXA7, HOXA10, HOXB4, and Mef2c. At 24-hr cultures, transcripts of myeloid leukemia cell lines for Bmi-1, Wnt-3a, β-Catenin and γ-Catenin were higher, and those of lymphoid leukemia cell lines for Notch 1, 2, and 3 were higher in group H compared with group L. Transcript levels for Wnt5a were higher at 10-hr culture (HL-60 and Raji), those for HOXA7 at 30–10-hr (MO-7E, U-266 and Raji), and those for Mef2c at 3-hr (MO-7E, U-266 and Raji) in group H compared with group L. Taken together, our present results favor the conclusions that genes related to transcription factors and growth factors are sequentially and differentially expressed through cell-to-cell interaction of leukemia cells. The nature of the leukemia cell-to-cell interacrtion, which is related to the growth advantages of leukemia stem cells over normal hematopoietic stem cells, remains to be further clarified.

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