scholarly journals Mir-155 Expression Raises the Apoptotic Threshold in Waldenström Macroglobulinemia By Inhibition of FOXO3a and Bim

Blood ◽  
2014 ◽  
Vol 124 (21) ◽  
pp. 1671-1671 ◽  
Author(s):  
Brian T Gaudette ◽  
Lawrence H. Boise
Keyword(s):  
Cell Line ◽  
Cell Lines ◽  
Conflicts Of Interest ◽  
Therapeutic Index ◽  
Fold Increase ◽  
Malignant Cell ◽  
Waldenström Macroglobulinemia ◽  
Waldenstrom Macroglobulinemia ◽  
Apoptotic Proteins ◽  
Induced Apoptosis

Abstract Waldenström Macroglobulinemia (WM) is a proliferative disorder of lymphoplasmacytic cells in the lymph nodes and bone marrow. Phenotypically, WM cells are CD19+, CD20+, CD22+, CD38+, CD138+/- and are lymphoid or plasmacytic in morphology. The disease is characterized by abundant secretion of monoclonal, IgM which causes much of morbidity associated with WM. The disease carries a high prevalence of activating somatic mutations in MyD88 (91%) and CXCR4 (28%), which have been shown to contribute to poor prognosis. These mutations involve signaling cascades that activate pathways known to enhance survival signaling including Bcl-xL. Generally, upregulation of pro-apoptotic Bcl-2 family proteins is observed as cancer cells break differentiation and proliferation checkpoints. To counter this, it becomes necessary for the cell to increase expression of anti-apoptotic Bcl-2 proteins making it dependent on a particular protein or set of proteins for survival. However, we have previously shown data that Bcl-2 family expression in WM is characterized by low expression of both pro- and anti-apoptotic proteins. To investigate a mechanism for this regulation, we examined the Bcl-2 family expression in three WM cell lines and observed that in two lines, BCWM.1 and MWCL-1, the pro-apoptotic BH3-only protein Bim was expressed at very low levels or absent, respectively, which corresponded with low sensitivity to inducers of Bim-dependent intrinsic apoptosis including ABT-737 and dexamethasone. These cell lines were sensitive to bortezomib which can induce apoptosis independent of Bim via a tBid-dependent mechanism. In the third WM cell line, RPCI-WM1, Bim was expressed at moderate levels but the pro-apoptotic proteins Bak and Bax were underexpressed and absent, respectively, which rendered the cell line completely apoptosis-deficient. Having ruled out genomic copy number variation at the loci corresponding to these genes and finding no evidence of epigenetic silencing by methylation, we examined the expression of microRNAs targeting these genes. We first examined the predicted targets of seven commonly dysregulated microRNAs in WM. Of these only one, miR-494, was found to have a moderately conserved target site in the 3’ UTR of Bim. However, the expression pattern of miR-494 did not correlate with the pattern of Bim expression in the WM cell lines. None of these microRNAs were predicted to target Bax or Bak. Therefore, we examined the expression of the remaining commonly dysregulated microRNAs and found that miR-155 was expressed at much higher levels in BCWM.1 and MWCL-1 than in RPCI-WM1 or the multiple myeloma (MM) cell line MM1.s. miR-155 is known to both directly and indirectly regulate FOXO3a, a transcription factor important in the induction of Bim. Confirming this, we observed low protein expression of FOXO3a in both BCWM.1 and MWCL-1 cells. To test this mechanism we stably expressed an anti-miR that targets miR-155 or a control anti-miR in all three WM cell lines and observed an increase in mRNA for FOXO3a and Bim as well as an increase in Bim protein in BWCM.1 and MWCL-1 cells expressing anti-miR-155, while no effect on Bim was observed in the RPCI-WM1 line that does not express miR-155 at high levels. This corresponded with a two-fold increase in ABT-737-induced apoptosis in both BWCM.1 and MWCL-1 in the absence of any additional death signal. As expected, miR-155 antagonism did not significantly increase bortezomib-induced apoptosis. These data indicate that miR-155 expression raises the apoptotic threshold in WM by limiting FOXO3a-mediated Bim expression. Cancer therapy relies on the ability to kill malignant cells at a lower dose than would kill healthy cells. This therapeutic index relies heavily on what is termed mitochondrial priming which is a measure of the expression of pro-apoptotic proteins in a cell. The malignant cell remains alive due to sequestration of these proteins by anti-apoptotic proteins, yet requires less death signaling to cause release of sufficient quantities of pro-apoptotic proteins to activate apoptosis. The data presented here indicate that increased expression of miR-155 raises the apoptotic threshold of WM cells by inhibiting Bim expression and thereby compromises the therapeutic index of many agents. Therefore, the sensitivity to a variety of apoptosis-inducing therapies would be increased by targeting miR-155 in combination as part of the treatment modality. Disclosures No relevant conflicts of interest to declare.

The Potential Role of STAT's in Anti-Leukemic Therapy with Different Drugs

Blood ◽  
2012 ◽  
Vol 120 (21) ◽  
pp. 5120-5120
Author(s):  
Hatice Demet Kiper ◽  
Burcin Tezcanli Kaymaz ◽  
Ozlem Purclutepe ◽  
Ceyda Tunakan Dalgic ◽  
Nur Selvi ◽  
...  
Keyword(s):  
Cell Line ◽  
Cell Lines ◽  
Drug Exposure ◽  
Conflicts Of Interest ◽  
Time Dependent ◽  
Blue Dye ◽  
Dependent Manner ◽  
Down Regulation ◽  
Expression Levels ◽  
Induced Apoptosis

Abstract Abstract 5120 STAT pathways play a pivotal role in oncogenesis and leukemogenesis, thus targeting STAT signalling appears to be an effective anticancer treatment strategy. It has been described that constitutive activation of STAT3 and STAT5 plays a pro-oncogenic role both in acute and chronic myeloid neoplasms. In this study, we aimed to clarify the potential relationship between drug-induced apoptosis with different agents and STAT pathway. A third-generation bisphosphonate; zoledronate, an angiotensin-converting enzyme inhibitor (ACE-I); enalapril, a proteasome inhibitor which is used for treatment of multiple myeloma; bortezomib and a second-generation tyrosine kinase inhibitor; dasatinib were examined in this goal. Cell viability and cytotoxicity tests were conducted by using Trypan blue dye exclusion and XTT assays, respectively. Apoptotic analyses were performed by AnnexinV-EGFP staining method and fluorescence microscopy. Expression levels of STAT3, −5A and −5B genes were analysed in myeloid cell lines by qRT-PCR. The results showed that zoledronate; bortezomib and dasatinib decreased viability and proliferation and induced apoptosis in CML cell line K562 in a dose- and time-dependent manner which is associated by prominent decrease of STAT3, STAT5A and STAT5B mRNA expressions. Enalapril was also found to be cytotoxic and induced apoptosis in APL cell line HL60 in a dose- and time-dependent manner and the expression levels of STAT5A gene have significantly reduced in enalapril-treated HL60 cells as compared to untreated controls. Treatments of cell lines with other drugs were also associated with significant apoptosis in certain time points. The results and changes in expression of STAT's in mRNA level at 72nd hours are summarized in table. Taken together all these data showed that targeting STAT pathways by different drugs may be an appropriate approach in anti-leukemic therapy. This finding is important to propose that discovery or identification of novel agents targeted STATs may open new windows to the other hematological and solid malignancies which are associated with aberrant STAT expression. Table: The changes in STAT expressions after drug exposure in time-dependent manner with the dose of IC50. DRUGS CELL LINE IC50 APOPTOSIS (%) STAT3 mRNA Down Regulation (%) STAT5A mRNA Down Regulation (%) STAT5B mRNA Down Regulation (%) ENALAPRIL HL-60 7 μM 20 20* 76 5* ZOLEDRONATE K562 60 μM 34 63 31 57 BORTEZOMIB K562 177 μM 37 98 100 99 DASATINIB K562 3,314 nM 75 NA 33 78 * : Not significant NA: not applied Disclosures: No relevant conflicts of interest to declare.

scholarly journals Induction of Resistance to Proteasome Inhibition Preferentially Switches Survival Dependence from Bcl-2 to XIAP in Preclinical Models of Waldenstrom Macroglobulinemia: Pre-Clinical Rationale for Early Clinical Sequencing of ABT199

Blood ◽  
2015 ◽  
Vol 126 (23) ◽  
pp. 4839-4839
Author(s):  
Sharoon Akhtar ◽  
Aneel Paulus ◽  
Kelara Samuel ◽  
Hassan Yousaf ◽  
Davitte Cogen ◽  
...  
Keyword(s):  
Gene Expression ◽  
Cell Lines ◽  
Conflicts Of Interest ◽  
Family Members ◽  
Specific Inhibitor ◽  
Cross Resistance ◽  
Preclinical Models ◽  
Waldenström Macroglobulinemia ◽  
Waldenstrom Macroglobulinemia ◽  
Resistant Cells

Abstract Background: The proteasome is an established and druggable target for the treatment of plasma cell-related malignancies including Waldenstrom macroglobulinemia (WM). WM cells as a consequence of high immunoglobulin production and increased B-cell receptor (BCR) mediated proliferation upregulate proteasome activity. Additionally, microenvironmental influence mediated through BCR signaling directly influences Bcl-2 and its BH3 family members, supporting tumor cell survival. Indeed, WM patients derive significant clinical benefit from proteasome-inhibitor (PI) based therapy with agents such as bortezomib and carfilzomib. However, resistance to PI develops over time and for these patients the optimal choice and sequence of therapy has yet to be determined. Using our WM models of PI-resistance we interrogated molecular events within the BCR and Bcl-2 pathways to determine therapeutic potential of targeting these crucial pathway in PI-resistance. Materials & Methods: WM cell lines (BCWM.1 and MWCL-1) and carfilzomib-resistant (CR) subclones (BCWM.1/CR and MWCL-1/CR) were used in experiments. Gene-expression and long-noncoding (LNC) RNA analysis was performed (Arraystar) and validated by real-time PCR. Bortezomib, carfilzomib, ABT199 and ibrutinib were purchased from Sellekchem. Results: To determine the functional impact of BCR and Bcl-2 signaling in PI-resistance, as well as therapeutic sensitivity of PI-resistant cells to their inhibitors (ibrutinib, ABT-199, respectively), we established and characterized WM cell lines resistant to carfilzomib. BCWM.1/CR cells showed approximately 20-fold resistance to carfilzomib (IC50 = 92.75nM) and MWCL-1/CR cells approximately 10-fold resistance (Fig. 1A). Both CR clones also displayed some cross-resistance to bortezomib. Gene expression and LNC-RNA profiling demonstrated several changes between carfilzomib-resistant vs. sensitive WM cells. Analysis of proteasome-related mRNA revealed downregulation of PSMB5, PSMB1, PSMB2 and PSMB8. Similarly, profiling of BCR-associated genes demonstrated decreased expression of several components, including BTK and SPI1. This observation functionally manifested as reduced sensitivity to the BTK-inhibitor ibrutinib, wherein CR cells displayed 1.5 - 2 fold growth resistance to ibrutinib on 72hr MTS assay. Next we examined the expression of Bcl-2 family members in CR cells. Intriguingly, we observed that Bcl-2 and Mcl-1 were significantly downregulated but XIAP (inhibitor of apoptosis) was significantly increased in CR cells vs. wildtype WM cells- both at transcriptional and translational levels. This suggested that upon acquisition of CR, a transcriptional shift towards XIAP occurs to accommodate sustained therapeutic stress from carfilzomib and maintain steady antiapoptotic composure. To test if the PI-resistant cells have moved away from their survival dependence on Bcl-2, we treated CR cells to increasing concentrations of the Bcl-2-specific inhibitor, ABT199, and as anticipated, CR cells displayed reduced apoptosis in presence of ABT199 compared to wildtype WM cells (32% annexin-V staining vs. 50%, respectively) (Fig. 1B). Conclusions: Our study sheds insight into the differential drivers of PI-resistance particularly towards carfilzomib, in WM cells. We demonstrate that acquisition of CR is associated with downregulation of Bcl-2 and Mcl-1, which is countered by upregulation of XIAP- an event that renders CR cells resistant to ABT199 (as it targets only Bcl-2). Likewise, downregulation of BCR-related components in CR cells was associated with reduced sensitivity towards ibrutinib. These observations suggest that acquisition of resistance to PI such as carfilzomib can impact future treatment with agents such as ibrutinib or ABT199. Our preclinical models provide rationale or early sequencing of ibrutinib or ABT199 in therapeutic planning of WM patients prior to induction of PI resistance. Figure 1. Figure 1. Disclosures No relevant conflicts of interest to declare.

The BH3 Mimetic, ABT-737, Overcomes Stromal-Mediated Pro-Survival Signals and Synergizes with PHA-767491, a Dual Cdc7/CDK9 Inhibitor, In Acute Myeloid Leukaemia

Blood ◽  
2010 ◽  
Vol 116 (21) ◽  
pp. 1841-1841
Author(s):  
Ruth C Morrell ◽  
Eva Szegezdi ◽  
Anna Halpin-McCormick ◽  
Karen Cawley ◽  
Afshin Samali ◽  
...  
Keyword(s):  
Acute Myeloid Leukaemia ◽  
Myeloid Leukaemia ◽  
Cell Line ◽  
Cell Lines ◽  
Conflicts Of Interest ◽  
In Vivo Studies ◽  
Relative Reduction ◽  
Induced Apoptosis ◽  
Cdk9 Inhibitor ◽  
Acute Myeloid

Abstract Abstract 1841 ABT-737 is a small molecule inhibitor of Bcl-2 and Bcl-xL with reported activity in pre-clinical in-vitro and in-vivo studies of acute myeloid leukaemia(AML) but to date no data has been reported on its activity in an AML co-culture model. To address this, we examined the effects of co-culture of AML cell lines (MOLM-13, ML-1, KG-1, OCI-AML2) with HS5 cells, a human stromal cell line, on sensitivity to Ara-C and ABT-737. All cell lines cultured in the presence of HS-5 stroma demonstrated a significant reduction in Ara-C-induced apoptosis (% relative reduction - OCI-AML2:80%; ML1:65%; MOLM-13:53%; KG-1:55%) as compared to cells cultured in suspension in normal complete media, with the effect on expression of Bcl-2 family members being currently under evaluation. In contrast, in the presence of ABT-737, HS-5 co-culture did not provide any protective effect whatsoever to AML cells, with IC50 ranging from 0.1 to 0.3μM in the cell lines noted above, regardless of the presence of stroma. OCI-AML3, an AML cell line known to express high levels of Mcl-1 was resistant to ABT-737 in both normal suspension cultures and co-culture. Indeed Mcl-1, an important pro-survival protein in haematopoietic cells is thought to be a key factor promoting resistance to ABT-737 and it has recently been reported that transcriptional upregulation of Mcl-1 may follow exposure to ABT-737. Thus, the combination of ABT-737 with strategies to deplete Mcl-1 is particularly attractive. Cdk9 inhibition is such a strategy. Since Cdk9 phosphorylates RNA polymerase II affecting the rate of transcription, inhibition leads to a depletion of proteins with short half-lives, such as Mcl-1. Here we report that resistance of OCI-AML3 cells to ABT-737-induced apoptosis can be overcome by combination with PHA-767491, a novel dual Cdc7/CDK9 inhibitor. OCI-AML3 cells were treated with increasing concentrations of ABT-737, PHA-767491 or both. Co-administration resulted in a strong synergistic apoptosis-inducing effect as assessed by AnnexinV staining, with combination indices, as calculated by Chou et Talalay, for a range of doses of both drugs of <1 (range 0.3–0.9). Importantly, the sensitising effect of PHA-767491 was seen only at concentrations (≥ 2μM) that resulted in significant downregulation of Mcl-1 protein expression, implicating Mcl-1 downregulation as a possible cause of synergy. We are currently investigating the precise role of Mcl-1 in this regard. In conclusion, taken together, these studies support that ABT-737, possibly in combination with agents to deplete Mcl-1, represents a promising therapeutic strategy for AML and warrants further evaluation. Disclosures: No relevant conflicts of interest to declare.

The Novel Organic Arsenical, Darinaparsin (ZIO-101), Induces Apoptosis through AKT and MEK/ERK Pathways In Hodgkin Lymphoma (HL) and T-Cell Lymphoma (TCL) Cell Lines

Blood ◽  
2010 ◽  
Vol 116 (21) ◽  
pp. 2840-2840
Author(s):  
Savita Bhalla ◽  
Sheila Prachand ◽  
Leo I Gordon ◽  
Andrew M Evens
Keyword(s):  
Mass Spectrometry ◽  
Cell Lines ◽  
Conflicts Of Interest ◽  
Annexin V ◽  
Inorganic Arsenic ◽  
Therapeutic Index ◽  
Mek Inhibitor ◽  
Jurkat Cells ◽  
Parp Activation ◽  
Induced Apoptosis

Abstract Abstract 2840 Background: The inorganic arsenic, arsenic trioxide (ATO), has a narrow therapeutic index, which has limited its clinical use in most malignancies. Darinaparsin (ZIO-101, S-dimethylarsino-glutathione), synthesized by conjugating dimethylarsenic to glutathione, is a novel organic arsenical that is under investigation as a novel agent for the treatment of cancer. Furthermore, early-phase clinical trials with darinaparsin have demonstrated low toxicity and encouraging clinical efficacy in relapsed/refractory hematologic malignancies. Methods: We treated several TCL cell lines (Jurkat, C10MJ, Hut-78, and MT2) and the resistant HL cell line, L428, with increasing concentrations of darinaparsin (0.5-5μM) +/− the MEK inhibitor, U0126, or ERK siRNA (Qiagen HiPerFect transfection). Cell survival and apoptosis were measured by MTT and Annexin-V/propidium iodide staining, respectively. Further, tumor intracellular darinaparsin and ATO concentrations were assessed with mass spectrometry, while transcription pathway intermediates were analyzed by Western blotting. Results: Darinaparsin inhibited cell growth and induced apoptosis in all cell lines at 1–3μM. At 2μm (48 hours), darinaparsin induced approximately 80% apoptosis in each of the four TCL lines, while 3μM resulted in 65% apoptosis in L428 cells. By comparison, >10μM of ATO (48 hours) was required to induce 40% apoptosis in TCL and 25% apoptosis in L428. At 1–3μM, darinaparsin induced significant increases in caspase 3 and PARP activation in TCL, while interestingly, minimal caspase or PARP was observed in L428. Notably, in L428 cells at 1 hour, mass spectrometry showed that intracellular accumulation of darinaparsin was >10-fold higher as compared with equivalent ATO concentrations (p<0.01). We also treated L428 cells with U0126 (5μM) or ERK2 siRNA, both combined with darinaparsin. Pre-incubation with U0126 or siRNA knock down of ERK2, followed by treatment with darinaparsin, significantly enhanced darinaparsin-induced apoptosis (p<0.05). To further investigate darinaparsin-induced signaling pathways, we analyzed phospho-AKT (p-AKT), and phospho-ERK (p-ERK) in Jurkat and L428. We found down-regulation of p-AKT in Jurkat as well as L428 cells, while total AKT remained unchanged. Additionally, an increase in p-ERK was observed in L428 cells with 2–3μM darinaparsin, while p-ERK was down-regulated in Jurkat cells. Conclusions: Darninaparsin induces significant cell death in HL and TCL cell lines that is mediated through AKT and MEK/ERK-based pathways. Additionally, markedly higher intracellular darinaparsin levels are achieved in lymphoma cells compared with equivalent concentrations of ATO. Continued pre-clinical and clinical trial investigation of darinaparsin in HL and TCL is warranted. Disclosures: No relevant conflicts of interest to declare.

Detection of SNPs of MTHFR Genes in Five Hematological Malignant Tumor Cell Lines

Blood ◽  
2012 ◽  
Vol 120 (21) ◽  
pp. 5130-5130
Author(s):  
Xiaoping Zhang ◽  
Ziying Jian ◽  
Baoan Chen ◽  
Peipei Xu ◽  
Miaoxin Peng ◽  
...  
Keyword(s):  
Cell Line ◽  
Cell Lines ◽  
Methylenetetrahydrofolate Reductase ◽  
Conflicts Of Interest ◽  
Raji Cell ◽  
Malignant Cell ◽  
Mthfr Gene ◽  
Nucleotide Polymorphisms ◽  
Flight Mass Spectrometry ◽  
Malignant Tumor Cell

Abstract Abstract 5130 Background & Aim: This study detected three single nucleotide polymorphisms (SNPs) of methylenetetrahydrofolate reductase (MTHFR) gene in five hematology malignant cell lines, to find correlations between MTHFR gene SNPs and hematological malignancies by horizontal comparison. Materials & Methods: Cell line K562, Ka, HL-60, U937, and Raji were cultured. The genomic DNA was isolated by QIAamp DNA Blood Mini kit. Designing primes were amplified by PCR to get the related DNA fragments. MTHFR gene A1298C (rs1801131), C677T (rs1801131), G1793A (rs2274976) was genotyped by means of matrix assisted laser desorption ionisation-time of flight mass spectrometry method (MALDI-TOFMS). Results: The results showed that the genotype of locus A1298C (rs1801131) on MTHFR gene was AA for U937 cell line. While for K562, Ka, HL-60, and Raji cell lines, that was CA. For all the five hematology malignancies cell lines, the genotype of locus C677T (rs1801133) on the MTHFR gene was CC, and that of locus G1793A (rs2274976) was GG. Conclusion: The genotype of locus A1298C (rs1801131) on MTHFR gene was not all the same in the detected hematology malignant cell lines, while the genotypes of the other 2 loci were same in the 5 cell lines. Disclosures: No relevant conflicts of interest to declare.

Combinatorial Targeting of BCL6 and Anti-Apoptotic Proteins in Diffuse Large B-Cell Lymphoma (DLBCL) and Follicular Lymphoma (FL)

Blood ◽  
2012 ◽  
Vol 120 (21) ◽  
pp. 64-64
Author(s):  
Thibault Dupont ◽  
Zhenghong Dong ◽  
ShaoNing Yang ◽  
Ari Melnick ◽  
Leandro Cerchietti
Keyword(s):  
Cell Line ◽  
Cell Lines ◽  
Conflicts Of Interest ◽  
Constitutive Expression ◽  
B Cell Lymphoma ◽  
Cell Of Origin ◽  
Mutational Status ◽  
Apoptotic Genes ◽  
Apoptotic Proteins ◽  
The Impact

Abstract Abstract 64 BCL6 represents a survival factor in DLBCL and FL since specific BCL6 inhibitors (i.e: the peptidomimetic RI-BPI and the small molecule 79-6) kill DLBCL and transformed FL (tFL) cell lines. Our group showed that BCL2 and other anti-apoptotic genes are transcriptionally repressed by BCL6 and could be reactivated upon treatment with RI-BPI or 79-6. We also showed that BCL6 and BCL2 control distinct and non-overlapping survival pathways in these lymphomas. This suggests that blocking the function of anti-apoptotic proteins might overcome any resistance that these proteins might mediate in response to BCL6 inhibition. In addition, constitutive expression of BCL2 has been observed in DLBCL and FL cases. We therefore hypothesized that targeting both BCL6 and BCL2 would eliminate two of the most potent survival mechanisms and would translate in synergistic killing of these lymphomas. In order to test this hypothesis, we examined the proteome-wide consequence of BCL6 inhibition in a DLBCL cell line (SU-DHL6) transfected with siBCL6 by phospho-protein arrays. We found that 280 unique proteins changed their abundance after siBCL6, 40 of them related to (pro and anti) apoptosis signaling (p<0.001). By means of pathway analysis bioinformatic tools, we then identified anti-apoptotic proteins with increased abundance after siBCL6 that could be therapeutically targeted. Among these druggable proteins we found BCL2, BCL-XL, MCL-1, NEDD8, PARP1 and several ubiquitin ligases. We confirmed in independent experiments that BCL6 knockdown induced mRNA (by qPCR) and protein up-regulation (by immunobloting) of these genes in 2 additional DLBCL and 2 tFL cell lines. Treatment of these siBCL6-transfected cell lines with small molecules inhibitors of BCL2 family members (ABT-737 and oblatoclax), NEDD8 activating enzyme (MLN4924), PARP (olaparib) and proteasome (bortezomib) showed increased killing compared to each treatment alone. In order to identify rational combinatorial therapies that could be potentially translated for use in clinical trials, we performed additional studies with the BCL6 inhibitor RI-BPI that is being developed for clinical use. We first analyzed the impact of RI-BPI on the apoptosome in a panel of 6 DLBCL (SU-DHL6, Ly1, Ly7, Ly3, Ly10, SU-DHL4) and 4 tFL (DoHH2, WSU-DLCL2, Granta452, SC-1) cell lines. RI-BPI induced a profile of up-regulated pro and anti-apoptotic proteins similar to siBCL6. Because ABT-737 and obatoclax are active in DLBCL cells where apoptotic BH3 activators are neutralized by BCL2 or BCL-XL and RI-BPI treatment changes the stoichiometry of pro and anti-apoptotic proteins, we determined the post-RI-BPI BH3 profiling accordingly to the amount of BIM sequestration (by co-immunoprecipitation). Accordingly, sequential treatment of DLBCL and tFL cell lines with RI-BPI and ABT-737 or obatoclax synergistically killed BCL2/BCL-XL dependent cells (but not MCL-1 dependent cells). This effect was independent of the mutational status of BCL2, MCL1, BCL6, MYC and TP53. Olaparib was not tested in combination since most cell lines were resistant to clinically achievable concentrations of this drug. Bortezomib and MLN4924 were synergistic in most cell lines when combined with RI-BPI (as determined by isobologram analysis). The synergistic killing was associated with increase in caspase 7/3 activation (by a plate-based assay) and NFkB inhibition (by p65 DNA binding assay). This effect was independent of the cell of origin classification of the cell line (i.e. ABC vs. GCB). We then tested the combination of RI-BPI with ABT-737, MLN4924 or bortezomib in Ly1 xenograft models (n=10 mice per combination). Ly1 represents a DLBCL with 3q27 and t(14,18). We found that after 10 days of treatment, each combinatorial treatment was more effective than their individual components (p=0.02, p=0.01 and p<0.01 for RI-BPI with ABT-737, MLN4924 and bortezomib, respectively; T-test, day 10). Detailed toxicity studies revealed no toxicity excess with these combinations. In sum, our work shows that pharmacologic targeting of anti-apoptotic pathways induced by inhibition of BCL6 activity successfully sensitized DLBCL and tFL cells to apoptosis. This effect was evident in cells in which the apoptosis resistant mechanism evolved as response to BCL6 inhibition and gene de-repression as well as those with constitutive overexpression of anti-apoptotic genes. Disclosures: No relevant conflicts of interest to declare.

PD-1 Is Expressed on B-Cells in Waldenstrom Macroglobulinemia and Promotes Malignant Cell Viability and Proliferation

Blood ◽  
2014 ◽  
Vol 124 (21) ◽  
pp. 3015-3015
Author(s):  
Stephen M. Ansell
Keyword(s):  
Bone Marrow ◽  
Flow Cytometry ◽  
B Cells ◽  
Cell Growth ◽  
Cell Lines ◽  
Stromal Cells ◽  
Malignant Cell ◽  
Growth And Survival ◽  
Waldenström Macroglobulinemia ◽  
Waldenstrom Macroglobulinemia

The tumor microenvironment plays an important role in regulating malignant cell growth and mechanisms to enhance anti-tumor immune function have been shown to improve patient outcome. Interactions between programmed death 1 (PD-1) and its ligands (PD-L1 and PD-L2) have been shown to be an important checkpoint in immune regulation. While it is well known that PD-1 is expressed on normal T cells and signaling through PD-1 inhibits T cell function, PD-1 is also expressed on a subset of B-cells but little is known about PD-1 signaling in B-cells. The goal of this study was to determine if the PD-1 is expressed on malignant B cells in Waldenstrom macroglobulinemia (WM) and whether this pathway plays a role in the survival and growth of malignant B cells in this B cell lymphoma. Using flow cytometry, we found that the cell lines MWCL-1, BCWM.1 and RPCI, all derived from patients with Waldenstrom macroglobulinemia, expressed PD-1 to varying degrees on their cell surface. PD-1 expression in the cell lines was further confirmed by RT PCR analysis. Using flow cytometry and immunohistochemistry to examine bone marrow specimens from WM patients, we further confirmed PD-1 expression on CD19+ CD138+ malignant B-cells. Furthermore, intense staining for the ligands PD-L1 and PD-L2 was found by in bone marrows of WM patients when compared to normal bone marrow specimens. When WM cell lines are co-cultured with stromal cells engineered to express PD-L1 or PD-L2, there was a consistent increase in cell viability compared to controls. When malignant B cells from WM patients were co-cultured with stromal cells expressing the ligands, viability was unchanged but there was an increase in cell proliferation, most noticeably when cocultured with cells expressing PD-L2. To determine potential mechanisms that account for upregulation of PD-1 on malignant B-cells, we tested whether cytokines that promote WM cell growth and survival, including IL-6, IL-21 and BAFF, increased PD-1 expression. We found that WM cell lines and patient derived CD19+CD138+WM B-cells (n=4) treated with IL-21 demonstrated an increase in PD-1 expression compared to untreated controls. We conclude that PD-1 is expressed on malignant B-cells in WM and that signaling through PD-1 may promote WM cell growth and survival. Blocking PD-1/PD ligand interactions may therefore be a potential therapeutic strategy in patients with Waldenstrom macroglobulinemia. Disclosures No relevant conflicts of interest to declare.

Apoptotic Effects of N-(2-hydroxyphenyl)-2-propylpentanamide on U87-MG and U-2 OS Cells and Antiangiogenic Properties

2020 ◽  
Vol 20 ◽  
Author(s):  
Paola Castillo-Juárez ◽  
Sebastián C. Sanchez ◽  
Alma D. Chávez-Blanco ◽  
Humberto Mendoza-Figueroa ◽  
José Correa-Basurto
Keyword(s):  
Cell Line ◽  
Cell Lines ◽  
Cancer Cell ◽  
Histone Deacetylases ◽  
Biochemical Mechanism ◽  
Antiproliferative Effects ◽  
Human Osteosarcoma ◽  
Antiproliferative Agent ◽  
Induced Apoptosis ◽  
Apoptotic Effects

Background and Objective: Histone deacetylases (HDACs) are important therapeutic targets for many types of human cancers. A derivative of valproic acid, N-(2-hydroxyphenyl)-2-propylpentanamide (HO-AAVPA), has antiproliferative properties on some cancer cell lines and inhibits the HDAC1 isoform. Materials and Methods: In this work, HO-AAVPA was tested as an antiproliferative agent in U87-MG (human glioblastoma) and U-2 OS cells (human osteosarcoma), which are types of cancer that are difficult to treat, and its antiangiogenic properties were explored. Results: HO-AAVPA had antiproliferative effects at 48 h with an IC50 = 0.655 mM in U87-MG cells and an IC50 = 0.453 mM in U-2 OS cells. Additionally, in the colony formation assay, HO-AAVPA decreased the number of colonies by approximately 99% in both cell lines and induced apoptosis by 31.3% in the U-2 OS cell line and by 78.2% in the U87-MG cell line. Additionally, HO-AAVPA reduced the number of vessels in chorioallantoid membranes (CAMs) by approximately 67.74% and IL-6 levels in both cell lines suggesting that the biochemical mechanism on cancer cell of HO-AAVPA is different compared to VPA. Conclusion: HO-AAVPA has antiproliferative effects on glioblastoma and osteosarcoma and antiangiogenic properties.

scholarly journals A Gain of Function Mutation in the NSD2 Histone Methyltransferase Drives Glucocorticoid Resistance Via Blocking Receptor Auto-Induction and BIM/Bmf Expression in ALL

Blood ◽  
2019 ◽  
Vol 134 (Supplement_1) ◽  
pp. 3758-3758
Author(s):  
Jianping Li ◽  
Catalina Troche ◽  
Julia Hlavka Zhang ◽  
Jonathan Shrimp ◽  
Jacob S. Roth ◽  
...  
Keyword(s):  
Cell Cycle ◽  
Cell Line ◽  
Cell Lines ◽  
Mutant Allele ◽  
Gene Editing ◽  
Conflicts Of Interest ◽  
Chemotherapeutic Agents ◽  
Rna Seq ◽  
Mesenchymal Transition ◽  
Pediatric All

Despite improvements in chemotherapy that have increased the 5-year survival rates of pediatric ALL to close to 90%, 15-20% of patients may relapse with a very poor prognosis. Pediatric ALL patients, particularly those in relapse can harbor a specific point mutation (E1099K) in NSD2 (nuclear receptor binding SET domain protein 2) gene, also known as MMSET or WHSC1, which encodes a histone methyl transferase specific for H3K36me2. To understand the biology of mutant NSD2, we used CRISPR-Cas9 gene editing to disrupt the NSD2E1099K mutant allele in B-ALL cell lines (RCH-ACV and SEM) and T-ALL cell line (RPMI-8402) or insert the E1099K mutation into the NSD2WT T-ALL cell line (CEM) and B-ALL cell line (697). Cell lines in which the NSD2E1099K mutant allele is present display increased global levels of H3K36me2 and decreased H3K27me3. NSD2E1099Kcells demonstrate enhanced cell growth, colony formation and migration. NSD2E1099K mutant cell lines assayed by RNA-Seq exhibit an aberrant gene signature, mostly representing gene activation, with activation of signaling pathways, genes implicated in the epithelial mesenchymal transition and prominent expression of neural genes not generally found in hematopoietic tissues. Accordingly, NSD2E1099K cell lines showed prominent tropism to the central neural system in xenografts. To understand why this NSD2 mutations are identified prominently in children who relapse early from therapy for ALL, we performed high-throughput screening in our isogenic cell lines with the National Center for Advancing Translation Science (NCATS) Pharmaceutical Collection and other annotated chemical libraries and found that NSD2E1099K cells are resistant to glucocorticoids (GC) but not to other chemotherapeutic agents used to treat ALL such as vincristine, doxorubicin, cyclophosphamide, methotrexate, and 6-mercaptopurine. Accordingly, patient-derived-xenograft ALL cells with NSD2E1099K mutation were resistant to GC treatment. Reversion of NSD2E1099K mutation to NSD2WT restored GC sensitivity to both B- and T-ALL cell lines, which was accompanied by cell cycle arrest in G1 and induced-apoptosis. Furthermore, knock-in of the NSD2E1099K mutation conferred GC resistance to ALL cell lines by triggering cell cycle progression, proliferation and anti-apoptotic processes. Mice with NSD2E1099K xenografts were completely resistant to GC treatment while treatment of mice injected with isogenic NSD2WT cells led to significant tumor reduction and survival benefit. To illustrate these biological phenotypes and understand the molecular mechanism of GC resistance driven by NSD2E1099Kmutation, we investigated the GC-induced transcriptome, GC receptor (GR) binding sites and related epigenetic changes in isogenic ALL cell lines in response to GC treatment. RNA-Seq showed that GC transcriptional response was almost completely blocked in NSD2E1099K cells, especially in T-ALL cell lines, correlating with their lack of biological response. GC treatment activated apoptotic pathways and downregulated cell cycle and DNA repair pathways only in NSD2WT cells. The critical pro-apoptotic regulators BIM and BMF failed to be activated by GC in NSD2E1099K cells but were prominently activated when the NSD2 mutation was removed. Chromatin immunoprecipitation sequencing (ChIP-Seq) showed that, the NSD2E1099K mutation blocked the ability of GR and CTCF to bind most GC response elements (GREs) such as those within BIM and BMF. While GR binding in NSD2WT cells was accompanied by increased H3K27 acetylation and gene expression, this failed to occur in NSD2 mutant cells. Furthermore, we found that GR RNA and protein levels were repressed in ALL cells expressing NSD2E1099K and GC failed to induce GR expression in these cells. Paradoxically, while H3K27me3 levels were generally decreased in NSD2E1099K cells, we saw increased levels of H3K27me3 at the GRE within the GR gene body where GR itself and CTCF normally bind, suggesting a novel role for the polycomb repressive complex 2 and EZH2 inhibitors for this form of GC resistance. In conclusion, these studies demonstrate that NSD2E1099K mutation may play an important role in treatment failure of pediatric ALL relapse by interfering with the GR expression and its ability to bind and activate key target genes. Gene editing screens are being performed to understand how to overcome this resistance. Disclosures No relevant conflicts of interest to declare.

Chromosome-mediated gene transfer of hydroxyurea resistance and amplification of ribonucleotide reductase activity

1983 ◽  
Vol 3 (6) ◽  
pp. 1053-1061
Author(s):  
W H Lewis ◽  
P R Srinivasan
Keyword(s):  
Cell Line ◽  
Cell Lines ◽  
Ribonucleotide Reductase ◽  
Chinese Hamster ◽  
Fold Increase ◽  
Resistant Cell ◽  
Plating Efficiency ◽  
Wild Type Cell ◽  
Wild Type ◽  
Metaphase Chromosomes

Metaphase chromosomes purified from a hydroxyurea-resistant Chinese hamster cell line were able to transform recipient wild-type cells to hydroxyurea resistance at a frequency of 10(-6). Approximately 60% of the resulting transformant clones gradually lost hydroxyurea resistance when cultivated for prolonged periods in the absence of drug. One transformant was subjected to serial selection in higher concentrations of hydroxyurea. The five cell lines generated exhibited increasing relative plating efficiency in the presence of the drug and a corresponding elevation in their cellular content of ribonucleotide reductase. The most resistant cell line had a 163-fold increase in relative plating efficiency and a 120-fold increase in enzyme activity when compared with the wild-type cell line. The highly hydroxyurea-resistant cell lines had strong electron paramagnetic resonance signals characteristic of an elevated level of the free radical present in the M2 subunit of ribonucleotide reductase. Two-dimensional electrophoresis of cell-free extracts from one of the resistant cell lines indicated that a 53,000-dalton protein was present in greatly elevated quantities when compared with the wild-type cell line. These data suggest that the hydroxyurea-resistant cell lines may contain an amplification of the gene for the M2 subunit of ribonucleotide reductase.

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