TET2 Downregulation Promotes AML Cell Proliferation Via Pim-1 Expression

Blood ◽  
2016 ◽  
Vol 128 (22) ◽  
pp. 5085-5085
Author(s):  
Qingxiao Chen ◽  
Jingsong He ◽  
Xing Guo ◽  
Jing Chen ◽  
Xuanru Lin ◽  
...  
Keyword(s):  
Cell Cycle ◽  
Flow Cytometry ◽  
Cell Proliferation ◽  
Western Blot ◽  
Cell Lines ◽  
Target Genes ◽  
Leukemia Cell ◽  
Leukemic Cells ◽  
Rna Seq ◽  
Knock Down

Abstract Background: Acute myeloid leukemia (AML) is the most common form of acute leukemia in adults which is still incurable although novel drugs and new combination of chemotherapies are used . With the development of genetic and molecular biology technologies, more and more genes are found to be related to leukemogenesis and drug resistance of AML. TET2, a member of the ten-eleven-translocation gene family which can modify DNA by catalyzing the conversion of 5-mehtyl-cytosine to 5-hydroxymethyl-cytosine , is often inactivated through mutation or deletion in myeloid malignancies. Recent research reported that TET2 knock-down can promote proliferation of hematopoietic stem cells and leukemic cells. Also, several clinical studies showed that patients with TET2 mutation or low levels of TET2 expression have more aggressive disease courses than those with normal levels of TET2. However, the mechanism of the phenomenon is unknown. Our aim is to uncover how TET2 protein level is negatively correlated with AML cell proliferation and to provide a better view of target therapy in AML. Methods: We determined the expression levels of TET2 and other target genes in acute leukemia cell lines, bone marrow AML specimens, and peripheral blood mononuclear cells from healthy donors by qRT-PCR and Western blot. We also determined the mutation status of TET2 in AML cell lines. CCK8 and flow cytometry were used to determine cell proliferation, cell apoptosis, and cell cycle profile. Methylation-specific PCR were used to examine the methylation status in gene promoter regions. Also, we developed TET2 knock-down lentivirus to transfect AML cell lines to examine the effect of TET2 depletion. Last, RNA-seq was used to compare gene expression level changes between TET2 knock-down cell lines and the control cell lines. Results: AML cells from AML cell lines (KG-1,U937, Kasumi, HL-60, THP-1, and MV4-11) and AML patients' specimens expressed lower levels of TET2 than those of PBMC from the healthy donor (P<0.05). Among AML cell lines, U937 barely expressed TET2, while KG-1 expressed TET2 at a relatively higher level than those of other AML cell lines. We constructed a TET2 shRNA to transfect KG-1,THP-1,MV-4-11,Kasumi,and HL-60, and used qRT-PCR and western blot to verify the knock-down efficiency. CCK8 confirmed that knocking down TET2 could increase leukemia cell proliferation (P<0.05). Flow cytometry showed that cell cycle profile was altered in TET2 knock-down cells compared to the negative control cells. In order to identify target genes, we performed RNA-seq on wildtype and TET2 knockdown KG-1 cells and found that the expression of cell cycle related genes, DNA replication related genes, and some oncogenes were changed. We focused on Pim-1, an oncogene related to leukemogenesis, which was significantly up-regulated in the RNA-seq profile. Western blot and qPCR verified the RNA-seq results of Pim-1 expression in the transfected cells . Also, AML patients' bone marrow samples (n=35) were tested by qPCR and 28 of them were found to express low TET2 but high Pim-1 with the other 7 being opposite. For detailed exploration in expression regulation of Pim-1 via TET2, we screened genes affecting Pim-1 expression and found SHP-1, a tumor suppress gene which is often silenced by promoter methylation in AML. Western blot band of SHP-1 was attenuated in TET2 knockdown KG-1 cells. Moreover, methylation-specific PCR showed that after knocking down TET2 in KG-1 cell line, the promoter regions were methylated much more than the control cells. These results indicated that the function of TET2 in epigenetic modulation plays an important role in regulating Pim-1 expression. Finally, using flow cytometry and CCK8 we surprisingly found that knocking down TET2 expression could lead leukemic cells (KG-1, THP-1 and MV-4-11) more sensitive to Pim-1 inhibitor (SGI-1776 free base) and decitabine (a demethylation agent treating MDS and AML) (P<0.05). Conclusion: Our study showed that knocking down TET2 promoted leukemic cell proliferation. This phenomenon may correlate to Pim-1 up-regulation. Our clinical data also showed that the expression of TET2 and Pim-1 have an inverse relationship. The mechanism of TET2 regulating Pim-1 expression may be related to the epigenetic modulation function of TET2. Finally, we found TET2 downregulation could increase leukemia vulnerability to Pim-1 inhibitor and decitbine, and provide a novel view of target therapy in AML. Disclosures No relevant conflicts of interest to declare.

scholarly journals Sertad1 Antagonizes iASPP Function By Hindering Its Entrance into Nuclei to Interact with P53 in Leukemic Cells

Blood ◽  
2014 ◽  
Vol 124 (21) ◽  
pp. 5201-5201
Author(s):  
Shaowei Qiu ◽  
Jing Yu ◽  
Tengteng Yu ◽  
Haiyan Xing ◽  
Na An ◽  
...  
Keyword(s):  
Cell Cycle ◽  
Cell Proliferation ◽  
Cell Lines ◽  
Leukemia Cell ◽  
Leukemic Cell ◽  
K562 Cells ◽  
Expression Level ◽  
Leukemic Cells ◽  
Immunoblotting Analysis ◽  
Chemotherapy Drugs

Abstract Introduction: As the important suprressor of P53, iASPP was found to be overexpressed in leukemia, and functioned as oncogene that inhibited apoptosis of leukemia cells. Sertad1 is identified as one of the proteins that can bind with iASPP in our previous study by two-hybrid screen. Sertad1 is highly expressed in carcinomas from pancreatic, lung and ovarian tissues, which considered Sertad1 as an oncoprotein. In this study, our findings revealed that Sertad1 could interact with iASPP in the cytoplasm near nuclear membrane, which could block iASPP to enter into nucleus to interact with P53, and inhibited the function of iASPP eventually. Methods: Co-immunoprecipitation and fluorescence confocal microscopic imaging were used to confirm the interaction between iASPP and Sertad1, the exact binding domains and the subcellular colocalization.The plasmids of iASPP and Sertad1 were transfected alone or co-transfected into K562 cells, the stable subclones that highly expressed iASPP, Sertad1 or both of them were then established by limiting dilution and named as K562-iASPPhi, K562-Sertad1hi, and K562-Douhi, respectively. The cell proliferation, cell cycle and apoptosis of above subclones were investigated by flow cytometry. Further, silence of the above two proteins was performed to confirm their functions. Immunoblotting analysis and immunofluorescence were performed to explore the possible mechanisms of difference between the biological functions of the above subclones. Results: Sertad1 expression level varied in leukemic cell lines and AML patients irrespectively of iASPP and P53. Interaction between iASPP and Sertad1 did exist in 293 cell and leukemic cells, both iASPP and Sertad1 scattered in the cytoplasm and nucleus, and their colocalizations were mainly in the cytoplasm, which encircled the nucleus. iASPP binds directly to Sertad1 through its PHD-bromo domain, C-terminal domain and Cyclin-A domain in a reduced order, and Serta domain failed to bind to iASPP. Overexpression of iASPP in K562 cells (iASPPhi) could result in the increased cell proliferation, cell cycle arrest in G2/M phase and resistance to apoptosis induced by chemotherapy drugs. While overexpression of iASPP and Sertad1 at the same time (Douhi) could slow down the cell proliferation, lead the cells more vulnerable to the chemotherapy drugs. As figure showed, in K562-Douhi cells, both iASPP and Sertad1 were obviously located in the cytoplasm, which encircled the nuclei, the subcellular colocalization was nearly outside the nuclei. The immunoblotting analysis further supported the conclusions. The resistance of iASPP to chemotherapeutic drug was accompanied by Puma protein expression in a p53-independent manner. By knocking down the expersssion of iASPP and Sertad separately, we found that iASPP is dispensable for maintenance of anti-apoptotic function and Sertad1 is indispensable for cell cycle in leukemic cells. Conclusions: In normal situation, the protein iASPP and Sertad1 scatter in the nucleus and cytoplasm, mainly in the cytoplasm. As convinced by our study, iASPP was overexpressed in the leukemia cell lines and primary AML patients, it could function as oncogene through its binding with P53 protein in the nucleus, inhibit the function of P53. When iASPPhi cells were exposed to apoptosis stimuli, Puma protein could play an important role in this process, irrespective of the expression level of P53. But when iASPP and Sertad1 were both overexpressed in the leukemic cells, Sertad1 could tether iASPP outside the nucleus mainly through its PHD-bromo domain, prevent it from inhibiting P53 function, suppress the leukemic cell growth and stimulate cell apoptosis by rescuing the P53 eventually. Our data provided a new insight to overcome iASPP protein, namely through its binding partners, when the similar proteins or drugs that can tether iASPP outside the nucleus such as Sertad1 are transfected into the leukemic cells, it may restore p53 function to eliminate the leukemic cells. Figure 1 Figure 1. Disclosures Wang: Novartis: Consultancy; Bristol Myers Squibb: Consultancy.

scholarly journals Sirtuin 2 in Endometrial Cancer: A Potential Regulator for Cell Proliferation, Apoptosis and RAS/ERK Pathway

2020 ◽  
Vol 19 ◽  
pp. 153303382098078
Author(s):  
Yanjuan Guo ◽  
Nannan Zhao ◽  
Jianli Zhou ◽  
Jianxin Dong ◽  
Xing Wang
Keyword(s):  
Cell Proliferation ◽  
Endometrial Cancer ◽  
Western Blot ◽  
Cell Line ◽  
Cell Lines ◽  
Erk Pathway ◽  
Uterine Epithelial Cell ◽  
Knock Down ◽  
Ishikawa Cells ◽  
And Control

Objective: The present study aimed to explore the function of sirtuin 2 (SIRT2) on cell proliferation, apoptosis, rat sarcoma virus (RAS)/ extracellular signal-regulated kinase (ERK) pathway in endometrial cancer (EC). Methods: SIRT2 expression in human EC cell lines and human endometrial (uterine) epithelial cell (HEEC) line was assessed by reverse transcription-quantitative polymerase chain reaction (RT-qPCR) and western blot. SIRT2 knock-down and control knock-down plasmids were transfected into HEC1A cells, respectively; SIRT2 overexpression and control overexpression plasmids were transfected into Ishikawa cells, respectively. After transfection, SIRT2, HRas proto-oncogene, GTPase (HRAS) expressions were evaluated by RT-qPCR and western blot. ERK and phosphorylated ERK (pERK) expressions were evaluated by western blot. Meanwhile, cell proliferation and cell apoptosis were measured. Results: Compared to normal HEEC cell line, SIRT2 mRNA and protein expressions were increased in most human EC cell lines (including HEC1A, RL952 and AN3CA), while were similar in Ishikawa cell line. In HEC1A cells, SIRT2 knock-down decreased cell proliferation but increased apoptosis. In Ishikawa cells, SIRT2 overexpression induced cell proliferation but inhibited apoptosis. For RAS/ERK pathway, SIRT2 knock-down reduced HRAS and inactivated pERK in HEC1A cells, whereas SIRT2 overexpression increased HRAS and activated pERK in Ishikawa cells, suggesting that SIRT2 was implicated in the regulation of RAS/ERK pathway in EC cells. Conclusion: SIRT2 contributes to the EC tumorigenesis, which appears as a potential therapeutic target.

Analysis of Aurora Kinase Expressions and Cell Cycle Regulation by Aurora-C in Leukemia Cells.

Blood ◽  
2006 ◽  
Vol 108 (11) ◽  
pp. 1366-1366 ◽  
Author(s):  
Miki Kobayashi ◽  
Satoki Nakamura ◽  
Takaaki Ono ◽  
Yuya Sugimoto ◽  
Naohi Sahara ◽  
...  
Keyword(s):  
Cell Cycle ◽  
Western Blot ◽  
Cell Lines ◽  
Mammalian Cells ◽  
Cell Cycle Progression ◽  
Leukemia Cell ◽  
Leukemia Cells ◽  
Human Leukemia ◽  
Aurora A ◽  
Aurora Kinases

Abstract Background: The conserved Aurora family kinases, a family of mitotic serine/threonine kinases, have three members (Aurora-A, -B and -C) in mammalian cells. The Aurora kinases are involved in the regulation of cell cycle progression, and alterations in their expression have been shown to associate with cell malignant transformation. Aurora A localizes to the centrosomes during anaphase, and it is required for mitotic entry. Aurora B regulates the formation of a stable bipolar spindle-kinetochore attachment in mitosis. The function of Aurora-C in mammalian cells has not been studied extensively. In this study, we investigated that human leukemia cells expressed all 3 Aurora kinases at both protein and mRNA level, and the mechanisms of cell cycle regulation by knock down of Aurora C in leukemia cells. Methods: In this study, we used the 7 human leukemia cell lines, K562, NB4, HL60, U937, CEM, MOLT4, SUP-B15 cells. The expression levels of mRNA and proteins of Aurora kinases were evaluated by RT-PCR and western blot. The analysis of proliferation and cell cycle were performed by MTT assay and FCM, respectively. Results: The mRNA of Aurora-A and Aurora-B are highly expressed in human leukemia cell lines (K562, NB4, HL60, U937, CEM, MOLT4, SUP-B15 cells), while the mRNA of Aurora C is not only expressed highly in all cells. In contrast, an increase in the protein level of the 3 kinases was found in all cell lines. These observations suggested posttranscriptional mechanisms, which modulate the expression of Aurora C. In cell cycle analysis by flow cytometory, the knock down of Aurora C by siRNA induced G0/G1 arrest and apoptosis in leukemia cells, and increased the protein levels of p27Kip1 and decreased Skp2 by western blot. In MTT assay, it was revealed that the growth inhibition of leukemia cells transfected with siRNA Aurora C compared with leukemia cells untransfected with siRNA Aurora C. Moreover, We showed that Aurora C was associated with Survivin and directly bound to Survivin by immunoprecipitation and western blot. Conclusion: We found that human leukemia cells expressed all 3 members of the Aurora kinase family. These results suggest that the Aurora kinases may play a relevant role in leukemia cells. Among these Aurora kinases, Aurora C interacted with Survivin and prevented apoptosis of leukemia cells, and induced cell cycle progression. Our results showed that Aurora-C may serve as a key regulator in cell division and survival. These results suggest that the Aurora C kinase may play an important role in leukemia cells, and may represent a target for leukemia therapy.

scholarly journals Tris DBA Palladium Overcomes Hypoxia Mediated Drug Resistance in Multiple Myeloma

Blood ◽  
2015 ◽  
Vol 126 (23) ◽  
pp. 2978-2978
Author(s):  
Pilar De La Puente ◽  
Barbara Muz ◽  
Feda Azab ◽  
Micah John Luderer ◽  
Jack L. Arbiser ◽  
...  
Keyword(s):  
Cell Cycle ◽  
Multiple Myeloma ◽  
Flow Cytometry ◽  
Cell Proliferation ◽  
Drug Resistance ◽  
Cell Lines ◽  
Research Funding ◽  
Caspase 3 ◽  
Cellular Processes ◽  
Hypoxic Conditions

Abstract Introduction: Despite recent progress in novel and targeted therapies, multiple myeloma (MM) remains a therapeutically challenging incurable disease. The regulation of important cellular processes and its link to cancer presented Src as an attractive target for MM. Src is a non-receptor protein tyrosine kinase which regulates multiple fundamental cellular processes including cell growth, migration, survival and differentiation. Activated Src in cancer lead to studies with Src as a target for anti-cancer drugs, and numerous Src inhibitors have become available to test the importance of Src in tumor initiation and progression. In MM, it has been described that in cell lines and MM patient-derived tumors, c-Src is constitutively activated, which plays an important role in drug resistance mechanisms. Tris dibenzylideneacetone dipalladium (Tris DBA), a small-molecule palladium complex, was shown to reduce Src/NMT-1 complex in melanoma cells, as well as inhibit downstream signaling including mitogen-activated protein kinase (MAPK kinase) and phosphoinositol-3-kinase (PI3K). We suggest a novel strategy to improve the treatment of MM and overcome the drug resistance for the current therapeutic agents by specific inhibition of Src in MM cells by an organopalladium compound, Tris DBA. Methods: Tris DBA was prepared by Dr. Arbiser. MM cell lines (MM.1S, MM.1R, H929, RPMI-8826, and OPM2) and PBMCs were cultured with Tris DBA (0-10 µM) for 24h. MM cells were analyzed for cell proliferation by MTT assay; cell cycle by DNA staining with PI and analyzed by flow cytometry; apoptosis was analyzed by Annexin V/PI staining and analyzed by flow cytometry; and cell signaling associated with proliferation, cell cycle, and apoptosis was analyzed by western blotting. In addition, cell proliferation assay of Tris DBA with or without combination of proteasome inhibitors (PIs) bortezomib or carfilzomib for 24h was analyzed on the proliferation of MM cells in normoxic or hypoxic conditions. Moreover, we tested the effect of combination treatment on cell cycle and apoptosis signaling under normoxic conditions. We then evaluated the effect of Tris DBA on HIF1α expression, migration and drug resistance under normoxic or hypoxic conditions. Results: The Src inhibitor Tris DBA reduced the proliferation of MM cell lines with an IC50 of about 1.5 - 3 µM after 24h treatment as a single agent, while none of the normal PBMC controls showed effect on their proliferation in the same dose range. These results were consistent with the decreased expression of proliferation signaling proteins from MAPK pathways (pERK), as well as PI3K (pS6R). Src inhibition led to the induction of a sub-G1 peak, which indicated accumulating apoptotic cells shown by DNA staining with PI. Apoptosis was then analyzed by Annexin/PI and confirmed by cleavage of caspase-3 and PARP. We found that Tris DBA synergized with bortezomib and carfilzomib by inhibiting proliferation of MM cells and reducing cell cycle protein signaling more than either of the drugs alone. Moreover, the Tris DBA/Bortezomib or Tris DBA/Carfilzomib combination therapies significantly increased apoptosis by caspase-3 cleavage more than treatment with either proteasome inhibitor individually. Tris DBA inhibited HIF1α expression in both normoxic and hypoxic conditions. HIF1α is an important target for hypoxia-driven drug resistance. Our studies confirmed hypoxia promoted faster chemotaxis of MM cells towards the chemo-attractants found in stromal cell conditioned media, and that Tris DBA treatment could overcome this hypoxia-induced effect. In addition, the development of hypoxia-induced drug resistance to individual bortezomib or carfilzomib treatment was overcome with combination treatment of Tris DBA under hypoxic conditions. Conclusions: Tris DBA reduces proliferation and induces G1 arrest and apoptosis in MM cells. Tris DBA synergized with PIs reducing proliferation and cell cycle signaling, as well as increasing apoptosis more than each drug alone. Tris DBA overcame hypoxia-induced effects such as enhanced chemotaxis or drug resistance to PIs by inhibition of HIF1α expression. Moreover, we found that Tris DBA is an effective anti-myeloma agent alone or in combination with other targeted drugs and that it reverses hypoxia-induced drug resistance in myeloma. These results suggest the use of Tris DBA as a new therapeutic agent in relapsed refractory myeloma. Disclosures Arbiser: ABBY Therapeutics: Other: Jack L Arbiser is listed as inventor on a US Patent for imipramine blue. He is cofounder of ABBY Therapeutics, which has licensed imipramine blue from Emory University.. Azab:Verastem: Research Funding; Targeted Therapeutics LLC: Other: Founder and owner ; Selexys: Research Funding; Karyopharm: Research Funding; Cell Works: Research Funding.

scholarly journals m6A demethylase ALKBH5 promotes tumor cell proliferation by destabilizing IGF2BPs target genes and worsens the prognosis of patients with non-small cell lung cancer

2021 ◽  
Author(s):  
Kazuo Tsuchiya ◽  
Katsuhiro Yoshimura ◽  
Yuji Iwashita ◽  
Yusuke Inoue ◽  
Tsutomu Ohta ◽  
...  
Keyword(s):  
Lung Cancer ◽  
Cell Cycle ◽  
Cell Proliferation ◽  
Small Cell Lung Cancer ◽  
Cell Lines ◽  
Target Genes ◽  
Small Cell ◽  
Lung Cancer Cell ◽  
Small Cell Lung ◽  
Proliferation Ability

Background: The modification of N6-methyladenosine (m6A) in RNA and its eraser ALKBH5, an m6A demethylase, play important roles across various steps of human carcinogenesis. However, the involvement of ALKBH5 in non-small cell lung cancer (NSCLC) development remains to be completely elucidated. Methods: The current study investigated the involvement of ALKBH5 in NSCLC development using immunostaining of clinical NSCLC specimens as well as cancer-related cellular functions (cell proliferation, migration ability, cell cycle, and apoptosis) in ALKBH5-knockdown lung cancer cell lines. Moreover, a microarray was utilized to comprehensively analyze mRNA and m6A in ALKBH5-knockdown cells. m6A target genes were identified using the methylated RNA immunoprecipitation (MeRIP) assay with m6A antibody. Furthermore, mRNA stability and protein expression owing to m6A modification (the target genes) were examined. Results: Clinicopathological analysis revealed that increased ALKBH5 expression was an independent prognostic factor associated with unfavorable overall survival in NSCLC (hazard ratios, 1.468; 95% confidence interval, 1.039—2.073). In vitro study revealed that ALKBH5 knockdown suppressed cell proliferation ability of PC9 and A549 cells as well as promoted G1 arrest and increased the number of apoptotic cells. Furthermore, ALKBH5 overexpression increased the cell proliferation ability of the immortalized cell lines BEAS2B and HEK293. Comprehensive analysis of microarray and MeRIP quantitative-polymerase chain reaction revealed that 3′ untranslated regions (3′ UTRs) of CDKN1A, TIMP3, E2F1, and CCNG2 mRNA were potential targets of ALKBH5. Depending on the lung cancer cell lines, increased expression of CDKN1A or TIMP3 and decreased cell proliferation were observed by ALKBH5 knockdown. These alterations were offset by a double knockdown of both ALKBH5 and one of the IGF2BPs. The decline of mRNAs was, at least partly, owing to the destabilization of these mRNAs by one of the IGF2BPs. Conclusions: Upregulation of ALKBH5 in NSCLC reduces m6A modifications on the 3′ UTR of specific genes. Loss of m6A causes a decrease in opportunity for recognition by IGF2BPs and destabilizes the target transcript, such as CDKN1A (p21) and TIMP3. Downregulation of CDKN1A (p21) and TIMP3 induces cell cycle alteration and inhibits apoptosis. The ALKBH5—IGF2BPs axis promotes cell proliferation and tumorigenicity, which in turn causes the unfavorable prognosis of NSCLC.

MDM2 Inhibitor Nutlin-3a Triggers Autophagic Cell Death In Addition to Apoptosis In Leukemia Cell Lines with Wild-Type p53

Blood ◽  
2010 ◽  
Vol 116 (21) ◽  
pp. 3300-3300
Author(s):  
Seshagiri Duvvuri ◽  
Vivian Ruvolo ◽  
Duncan H. Mak ◽  
Kensuke Kojima ◽  
Marina Konopleva ◽  
...  
Keyword(s):  
Flow Cytometry ◽  
Cell Death ◽  
Western Blot ◽  
Cell Lines ◽  
Research Funding ◽  
Leukemia Cell ◽  
Annexin V ◽  
Dependent Manner ◽  
Autophagic Vacuoles ◽  
Leukemia Cell Lines

Abstract Abstract 3300 Background: Nutlin-3a is a small molecule inhibitor of MDM2 and has been shown to induce apoptosis and cell cycle arrest in various cancer models in a p53 dependent manner. Autophagy is a programmed cell death that can occur concurrently with apoptosis or in its absence. There is significant debate whether autophagy is a protective mechanism or a bona fide mechanism of cell death. While autophagy can function as tumor cell defense mechanism against cellular stress induced death, mutation/loss of alleles of certain genes regulating autophagy have been associated with development of cancer (e.g. Beclin-1 in breast cancer [Nature, 1999, 402: 672–676]). Multiple proteins involved in autophagy are transcriptional targets of p53 but Nutlin-3a has not been evaluated for its role in inducing autophagy. Here we present data suggesting that low dose Nutlin-3a induces autophagy in addition to apoptosis in leukemia cell lines in a p53 dependent manner. Methods and results: OCI-AML-3 cells (p53-WT) treated with Nutlin-3a (2.5 and 5.0μM for 48, 72 and 96 hrs) were stained with mono-dansyl-cadaverine (MDC), a dye that accumulates in acidic autophagic vacuoles. OCI-AML-3 cells showed increasing staining with MDC in a dose and time dependent fashion by both flow cytometry (54%, 57% and 51% MDC positive after treatment with Nutlin-3a 5.0μM for 48, 72 and 96 hrs) and by confocal microscopy. Nutlin-3a treated cells also were positive for Annexin-V (flow cytometry 22%, 26% and 36% at 48, 72 and 96 hrs time points), and some of the cells were double-positive for Annexin-V and MDC (9.2%, 5% and 7% at 48, 72 and 96 hrs) suggesting that both apoptosis and autophagy can occur simultaneously. Autophagy induction was confirmed by Transmission Electron Microscopy (TEM). Large, multiple autophagic vacuoles were observed in OCI-AML-3 cells treated with Nutlin-3a. OCI-AML-3 cells with stable p53 knockdown by shRNA or HL-60 cells (p53-null) did not show increased MDC staining by flow cytometry (both cell lines) or autophagic vacuoles by TEM (HL-60) after similar treatment. Western blot analysis showed increases in LC3-II and in conjugation of Atg5/12, early and late autophagy markers respectively, in OCI-AML-3 cells after treatment with Nutlin-3a. Increased expression of the autophagy markers (LC3-II and Atg 5/12 conjugate) were also seen by Western blot analysis in the ALL cell lines REH and NALM-6 (both p53-WT) after treatment with Nutlin-3a. Western blot and/or RT-PCR analysis showed upregulation of other p53 related proteins involved in autophagy e.g. DRAM, AMPK-β, LKB1, pLKB1 in OCI-AML-3 cells treated with Nutlin-3a. As mTOR/Akt pathway inhibits autophagy, analysis of mTOR targets showed downregulation of the total and phospho-ribosomal-S6-protein levels, whereas there was no change in total or phospho-4-EBP-1 levels. Knockdown of Beclin-1 (ATG6), one of the proteins required for initiation of the formation of autophagic vacuoles, caused reduction in autophagic vacuoles (MDC staining by confocal microscopy) in OCI-AML-3 and REH cells without affecting apoptosis induction (Annexin V by flow cytometry). Pharmacologic inhibition of late autophagy by Bafilomycin (10nM for 2 hours) reduced MDC staining in OCI-AML-3 cells treated with Nutlin-3a for 48 hrs (32% without and 9% with Bafilomycin) while having limited inhibition of apoptosis (Annexin V positive 42% without and 33% with Bafilomycin). Conclusion: Nutlin-3a induces autophagy in leukemia cells by a p53 dependent manner. We also demonstrate that autophagy could go hand-in-hand with apoptosis and in a fraction of cells both processes may occur concomitantly. Inhibition of autophagy does not necessarily enhance apoptosis. Disclosures: Andreeff: Roche: Research Funding. Borthakur:ASCO: Research Funding.

MLN4924, an Investigational Small Molecule Inhibitor of NEDD8-Activating Enzyme (NAE), Inhibits NF-κB Activity and Induces G1 Cell Cycle Arrest and Apoptosis in Pre-Clinical Models of Hodgkin Lymphoma (HL)

Blood ◽  
2012 ◽  
Vol 120 (21) ◽  
pp. 3717-3717
Author(s):  
Matthew J. Barth ◽  
Cory Mavis ◽  
Francisco J. Hernandez-Ilizaliturri ◽  
Myron S. Czuczman
Keyword(s):  
Cell Cycle ◽  
Flow Cytometry ◽  
Western Blot ◽  
Cell Viability ◽  
Tumor Cells ◽  
Cell Lines ◽  
Small Molecule ◽  
Wild Type ◽  
Cycle Arrest ◽  
Molecule Inhibitor

Abstract Abstract 3717 The incorporation of combined-modality therapy, risk-stratified chemotherapy selection, high-dose chemotherapy and autologous stem cell support (HDC-ASCS), and monitoring treatment response by functional imaging are factors that have contributed to the improvement in clinical outcomes in HL patients. Unfortunately, those patients not eligible for or that have failed HDC-ASCS remain a challenge for the treating oncologist, stressing the need for novel therapeutic strategies. Significant improvements in the understanding of the biology of HL have been achieved, including cellular pathways altered in HL (e.g. the ubiquitin-proteasome system) and the role of the tumor microenvironment. MLN4924 is an investigational small-molecule inhibitor of NEDD8-activating enzyme (NAE). NAE is an enzyme responsible for activating NEDD8, an ubiquitin-like molecule in the neddylation cascade that is responsible for cullin-ring ligase (CRL) mediated polyubiquitination of proteins targeting them for proteasomal degradation. In order to better understand the activity of MLN4924 in HL, we performed pre-clinical testing in IkB wild type (L-1236), IkB mutated (KM-H2 and L-428) HL cell lines, and in primary tumor cells derived from a HL patient. Malignant cells were exposed to escalating doses of MLN4924 and changes in cell viability were quantified at different time periods by alamar Blue reduction assay. Patient tumor cells were incubated with MLN4924 for 48 hrs and cell viability was determined using the CellTiterGlo assay. Induction of apoptosis in HL cell lines following exposure to MLN4924 was determined by flow cytometry for Annexin-V and propidium iodide (PI) staining and western blot for caspase-3 and PARP cleavage. Cell cycle analysis was performed by flow cytometry using PI staining. Inhibition of NAE by MLN4924 in HL cell lines was measured by western blot for NEDD8-cullin. Finally, changes in NF-kB activity following MLN4924 exposure were determined by p65 nuclear localization using Image stream technology. MLN4924 exhibited a dose- and time-dependent decrease in cell viability in all HL cell lines at nM concentrations. No differences in anti-tumor activity were observed between IkB-wild type (L-1236 IC50 = 250nM) and IkB–mutated HL cell lines (KM-H2 IC50 = 250nM and L-428 IC50 = 300nM). MLN4924 induced apoptosis in a dose-dependent manner in all cell lines tested. In addition, MLN4924 induced cell cycle arrest in G1 phase and inhibition of NAE was demonstrated by a decrease in NEDD8 conjugated CRL. L1236 cells exposed to MLN4924 also demonstrated a decrease in degradation of IκBα as evidenced by increased levels of p-IκBα following exposure to MLN4924 with a corresponding decrease in p65 nuclear translocation. Surprisingly KMH-2 cells, which carry a mutated IκBα protein that is truncated and non-functional, had a decrease in nuclear p65 following exposure to MLN4924, suggesting an alternative mechanism of NF-kB inhibitory activity by MLN4924. In summary, MLN4924 demonstrates activity against HL cells in vitro through inhibition of NF-kB, and is a promising novel agent for the treatment of HL. We continue to investigate the pre-clinical activity of MLN4924 both as a single-agent and in combination with traditional chemotherapy and other novel agents. Disclosures: No relevant conflicts of interest to declare.

scholarly journals Small Molecule Kinase Inhibitor Sunitinib Specifically Targets Juvenile Myelomonocytic Leukemia Cells with SHP2(PTPN11) Mutation

Blood ◽  
2021 ◽  
Vol 138 (Supplement 1) ◽  
pp. 3353-3353
Author(s):  
Chunxiao He ◽  
Yuming Zhao ◽  
Junbin Huang ◽  
Yao Guo ◽  
Hongman Xue ◽  
...  
Keyword(s):  
Flow Cytometry ◽  
Western Blot ◽  
Signaling Pathway ◽  
Cell Lines ◽  
Drug Screening ◽  
Leukemia Cell ◽  
Juvenile Myelomonocytic Leukemia ◽  
Oncogenic Signaling ◽  
Leukemia Cell Lines

Abstract Juvenile myelomonocytic leukemia (JMML) is a highly fatal malignant disease in early childhood. It is still unknown of the specific pathogenesis, and there is shortage of effective targeted therapeutic approaches. Gain of function SHP2 mutation encoded by PTPN11 gene is found in approximately 35% of JMML patients, which maybe contributed to its pathogenesis. JMML patients with SHP2 mutation have lower survival rate and higher recurrence rate. All of the above make development of new therapies imperative. Currently, there is no stable cell line that can accurately reflect the characteristics of JMML abnormal cells for research on JMML. In this study, we established two leukemia cell lines that depend on mutated SHP2 for survival, and discovered promising drugs that targeted mutated-SHP2-dependent oncogenic signaling pathway through drug screening method. HCD-57 cells are murine erythroleukemia cells that solely depend on exogenic erythropoietin (EPO) for survival. We constructed SHP2-D61Y and SHP2-E76K transformed HCD-57 cell lines through retroviral vectors, the survival of which dependent on mutated SHP2 mediated signaling pathway. Based on these cells, we established a drug screening platform and screened small molecule compound library containing 2862 FDA-approved drugs and 1707 kinase inhibitors. We performed cell viability, flow cytometry, Wright-Giemsa staining, and western blot to evaluate cells after drug treatment. To further assess therapeutic potential, we established in-vivo transplantation model that SHP2-D61Y transformed HCD-57 cells were implanted into immunodeficient NCG mice, and verified the effectiveness of the in-vitro screened drugs. We found that the survival and proliferation of HCD-57 cells transduced by SHP2-D61Y and SHP2-E76K no longer required EPO, but completely relied on the abnormal activation of signaling pathway mediated by mutated SHP2. Western blot results showed that the phosphorylation status of ERK1/2 and AKT of HCD-57 cells expressing SHP2 mutation were abnormally increased, consistent with SHP2-mutated JMML. Thus, we have obtained the leukemia cell lines that can represent the characteristics of activated signaling pathway in JMML with SHP2 mutation. Through drug screening, we observed that drug sunitinib (Sutent ®) selectively inhibits SHP2-mutated HCD-57 cell lines. CCK-8-based cell viability assay demonstrated a dose-dependent inhibition of SHP2-D61Y and SHP2-E76K transformed HCD-57 cell and no effects on the parental HCD-57 cells. Live cell counting with trypan blue revealed that the proliferation of SHP2-mutated HCD-57 cells was totally halted after one day upon treatment with 250 nM sunitinib, whereas the HCD-57 cells were unaffected. Wright-Giemsa staining demonstrated that SHP2-mutated HCD-57 cells showed no normal morphology change and no mitotic activity under sunitinib treatment, otherwise parental HCD-57 cells showed normal mitotic activity. Sunitinib induced apoptosis and cell cycle arrest at G1 phase in SHP2-mutated HCD-57 cells by flow cytometry, but had little effect on the parental HCD-57 cells. Sunitinib effectively downregulates the phosphorylation of ERK and AKT in SHP2-mutated cells, revealing the mechanism of sunitinib targeting SHP2-mutated cells. In addition, after transplantation of SHP2-D61Y transformed HCD-57 cells for 3 weeks, the spleen of NCG mice increased from an average of 45 mg to more than 300 mg; flow cytometry analysis showed that the implanted cells accounted for over 75% of the total nucleated cells in the bone marrow and spleen. Compared with the vehicle control, the number of monocytes in these mice was reduced to the normal range by treatment with sunitinib, and the spleen weights were reduced by about 50%. Histochemical staining showed disappearance of the myeloid infiltration in the spleen, liver and bone marrow. The above results all indicate that sunitinib has strong in-vivo anti-leukemia activity. Furthermore, western blot analysis showed that the administration of sunitinib significantly inhibited the phosphorylation expression level of AKT and ERK, indicating the effectivity of sunitinib in vivo. In conclusion, our data demonstrated that HCD-57 cell line is an effective tool for studying oncogenic signaling pathway and screening drugs that targeted JMML with SHP2 mutation. Sunitinib can be an effective drug for the targeted treatment of JMML in the future. Disclosures No relevant conflicts of interest to declare.

scholarly journals C-Myc-Driven and PRMT5-Dependent Regulation of Multiple Myeloma Cell Proliferation through TNRC6B Gene

Blood ◽  
2019 ◽  
Vol 134 (Supplement_1) ◽  
pp. 5520-5520
Author(s):  
Peipei Xu ◽  
Guo Dan ◽  
Bing Chen ◽  
Quan Zhao ◽  
Rong-Fu Zhou ◽  
...  
Keyword(s):  
Gene Expression ◽  
Multiple Myeloma ◽  
Cell Proliferation ◽  
Western Blot ◽  
Cell Lines ◽  
Myeloma Cell ◽  
Suppressor Gene ◽  
Rna Seq ◽  
Multiple Myeloma Cell ◽  
Arginine Residues

Objective: The protein arginine methyltransferase 5 (PRMT5) catalyzes the symmetrical bimethylation of arginine residues, which plays an important regulatory role in the life process. Transcription factor c-Myc is widely proved involved in the alteration and development of tumors, while the regulatory mechanism of c-Myc-mediated gene expression has not been fully understood. In this article we try to investigate the functional role of PRMT5 and c-Myc in regulating multiple myeloma cell proliferation. Methods: The protein and mRNA expression levels of PRMT5 in myeloma cells and normal cells were detected by Western Blot and qPCR. Lentivirally transduced shRNAs targeting PRMT5 (sh-PRMT5) was constructed using lentivirus mediated RNAi technology, and was packaged to infect MM cells to select positive colonies. The effect of PRMT5 on the proliferation of MM cells was detected by cck-8 assay. Annexin V/7-AAD double staining flow cytometry was used to detect cell survival and apoptosis rate. The expression of apoptotic suppressor gene c-Myc in sh-PRMT5 cell lines was detected by Western Blot and qPCR. Finally, double-knockdown of PRMT5 and c-myc was performed and gene expression differentiation were identified by RNA sequencing (RNA-seq). Results: PRMT5 expression in MM cell lines (RPMI8226 and U266) was relatively high compared with peripheral blood mononuclear cells (PBMCs), which was correlated with progression-free survival (PFS) and overall survival (OS) in MM patients. After sh-PRMT5 infection to MM cell lines, puromycin selection was performed and efficient gene knockdown was evaluated by Western Blot and qPCR. After targeted silencing of PRMT5 expression, the proliferation of MM cells was decreased and apoptosis was significantly increased (P < 0.05). C-Myc protein and mRNA levels were significantly downregulated after PRMT5 gene silencing. The results showed that PRMT5 promoted the proliferation of MM cells and inhibited the apoptosis of MM cells by regulating the expression of apoptotic suppressor gene c-Myc. Subsequently, RNA-seq confirmed SMCHD1 as the common candidate target gene of c-myc and PRMT5. Therefore, we speculated that PRMT5 and c-Myc may jointly regulate TNRC6B gene to promote the proliferation of MM cells. Conclusion: Altogether, our study not only proposed the mechanism PRMT5 and c-myc in regulating multiple myeloma related gene expression, but also provided a new strategy and theoretical basis for clinical treatment of multiple myeloma. Disclosures No relevant conflicts of interest to declare.

scholarly journals SYK-Inhibitor Bay 61-3606 Induces Cell Cycle Arrest and Apoptosis in Multiple Myeloma Cells Independent of SYK Inhibitory Effects but Via Degradation of IKZF1/3

Blood ◽  
2016 ◽  
Vol 128 (22) ◽  
pp. 4477-4477
Author(s):  
Shirong Li ◽  
Jing Fu ◽  
Jing Wu ◽  
Markus Y Mapara ◽  
Suzanne Lentzsch
Keyword(s):  
Cell Cycle ◽  
Cell Proliferation ◽  
Western Blot ◽  
Cell Cycle Arrest ◽  
Cell Lines ◽  
Western Blot Assay ◽  
Myeloma Cells ◽  
Cycle Arrest ◽  
Syk Inhibitor ◽  
Rpmi 8226

Abstract Introduction: Bay 61-3606 is a cell-permeable imidazopyrimidine compound that acts as a potent, ATP-competitive, reversible, and highly selective inhibitor of Syk tyrosine kinase activity with no inhibitory effect against Btk, Fyn, Itk, Lyn, and Src. BAY 61-3606 has been also shown to inhibit Syk-mediated cellular functions such as glucose-tyrosine phosphorylation of I κ B α and p65 nuclear translocation. It further exhibits a good oral bioavailability and in vivo efficacy in rat models. Recently, Bay 61-3606 was found to inhibit cell proliferation and SDF-1a-induced migration of MM cells (1). Based on these promising preliminary data we further investigated the potential of Bay 61-3606 as new anti-MM agent. Methods and Results: Bay 61-3606, at concentrations as low as 10 nM, induced significant (p<0.01) inhibition of cell growth in MM cells (MM.1S, H929 and RPMI-8266) as shown by WST-1 cell proliferation assay. The inhibition of proliferation was accompanied by increased cell cycle arrest at G0/G1 (from 60% to 75%). More importantly, Bay 61-3606 dose dependently induced MM cells apoptosis suggesting that Bay 61-3606 has potent anti-MM properties. Since Bay 61-3606 was originally reported as a SYK inhibitor, we analyzed whether the effects of Bay 61-3606 were due to SYK inhibition. For this purpose, we first checked the expression of SYK in all the MM cell lines (MM.1S, H929, U266, OPM2 and RPMI-8226). And to our surprise, although all these cells were sensitive to Bay 61-3606 treatment, several of these cell lines (H929, U266 and RPMI-8226) had no detectable SYK expression by Western Blot assay. This suggests that the anti-MM effects of Bay 61-3606 are not mediated by SYK inhibition, which was further confirmed by using another specific SYK inhibitor GS-9973. Further mechanistic studies showed that Bay 61-3606 significantly downregulated protein levels of IKZF1, IKZF3, c-MYC and IRF-4 in IMiD®-sensitive and resistant MM cell lines (MM.1S, H929 and RPMI-8266) by Western Blot assay. In contrast, real-time PCR assay indicated IKZF1/3-mRNA level was not altered, suggesting that Bay 61-3606 regulates IKZF1/3 at post-translational level. The proteinase inhibitor MG132 and cullin-dependent ubiquitin ligase inhibitor MLN4924 blocked the downregulation IKZF1/3 by Bay 61-3606 confirming that Bay 61-3606 induced IKZF1/3 protein degradation. Consistent with its proapoptotic effects, Bay 61-3606 downregulated MDM2 phosphorylation, upregulated P53 level and induced PARP cleavage as confirmed by Western Blot assy. Conclusion: In summary, our results demonstrate that Bay 61-3606 has anti-MM effects by inducing cell cycle arrest and apoptosis, and this effect is independent of SYK inhibition. Similar to IMiD® compounds, Bay 61-3606 induces IKZF1 and IKZF3 protein degradation in MM cells. More importantly, Bay 61-3606 has effects on both IMiD®-sensitive and resistant myeloma cells and may represent a novel potent anti-MM agent. References: (1). Koerber RM, et al. Exp Hematol Oncol. 2015. Disclosures Lentzsch: BMS: Consultancy; Foundation One: Consultancy; Celgene: Consultancy, Honoraria.

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