Heme Oxygenase-1(HO-1): A Promising Novel Target Molecule for Overcoming Imatinib Resistance in Chronic Myeloid Leukemia

Blood ◽  
2008 ◽  
Vol 112 (11) ◽  
pp. 4242-4242
Author(s):  
Jishi Wang
Keyword(s):  
Gene Expression ◽  
Chronic Myeloid Leukemia ◽  
Mrna Expression ◽  
Myeloid Leukemia ◽  
K562 Cells ◽  
Leukemia Cell Line ◽  
Dependent Manner ◽  
Rt Pcr ◽  
Imatinib Resistant ◽  
Resistant Cells

Abstract Objective : HO-1 is a microsomal enzyme catalyzing the first, rate-limiting step in degradation of heme, HO-1 is a inducible isoform of HO, it can be strongly induced in response to cellular stress and diverse oxidative stimuli, including its substrate heme, Many studies have convincingly shown that HO-1 is a cytoprotective and antiapoptotic enzyme. the objective of this study was to investigate the influence on the K562 cell growth and apoptosis after hemin-induced HO-1 expression, and to investigate the influence on K562 cells and imatinib-resistant CML cells after ZnPPIX-induced HO-1 inhibition. Methods: different concentrations hemin (0umol/l A20umol/l 30umol/l)was used respectively to induce HO-1 expression of cultured chronic myeloid leukemia cell line K562, then detected HO-1 mRNA expression under different time by RT-PCR, and MTT was used to detected the viability of K562 cells. In addition, we used STI571(2 μmol/L) deal with the hemin-induced cells, then confirm HO-1 protective effect against STI571 use MTT. Then ZnPPIX was used to inhibition HO-1 expression of K562 and imatinib-resistant cells, similarly, RT-PCR and MTT was used for analyzed. Results: The HO-1 mRNA was not tested when absence of hemin, 8h after treated with hemin of 20 μmol/L, we can test the HO-1 mRNA expression, and at 16h the expression is reach to the peak, 16h after treated hemin under different concentrations (10umol/l, 20umol/l, 30umol/l), we found the expression is in a dose-dependent manner. In the group of 10 umol/l and 20 umol/l, the survival of cells is significantly increased in comparison to the control and also have significantly difference in the two groups(p<0.05), in the group of 20 μmol/L, 16h to 48h after hemin-induced, the survival of cells presents a time-dependent manner. In the group of 10μmol/L and 20 μmol/L, exposure of K562 cells to STI571 resulted in a substantial decrease of cell viability in comparison to the STI571 single treatment group(p<0.05). ZnPPIX-induced HO-1 inhibition leads to induction of apoptosis in K562 cells, having significant difference with the control group(p<0.05). ZnPPIX-induced HO-1 inhibition can suppress the survival of imatinib-resistant cells(p<0.05). Conclusion: our studies have shown that hemin-induced HO-1 gene expression may promote the proliferation of K562 cells, and can against the cell apoptosis. And we found hemin-induced HO-1 gene expression can protect K562 cells against STI571-induced apoptosis, ZnPPIX-induced HO-1 inhibition leads to decreased viability of imatinb-resistant CML cells. these all indicates HO-1 may represent a novel targeting in CML.

scholarly journals The Role of Hypoxia on ABL Tyrosine Kinase Inhibitor Resistant Chronic Myeloid Leukemia Cells

Blood ◽  
2019 ◽  
Vol 134 (Supplement_1) ◽  
pp. 5369-5369
Author(s):  
Seiichi Okabe ◽  
Yuko Tanaka ◽  
Mitsuru Moriyama ◽  
Akihiko Gotoh
Keyword(s):  
Gene Expression ◽  
Stem Cells ◽  
Bone Marrow ◽  
Chronic Myeloid Leukemia ◽  
Myeloid Leukemia ◽  
K562 Cells ◽  
Leukemia Cells ◽  
Leukemia Stem Cells ◽  
Transfected Cells ◽  
Resistant Cells

Introduction: ABL tyrosine kinase inhibitors (TKIs) improved outcomes for patients with chronic myeloid leukemia (CML) and Philadelphia chromosome (Ph)-positive leukemia, however, some patients are still resistance to ABL TKIs. One of the most common mechanisms involves point mutations in the kinase domain of BCR-ABL1, however, mechanisms of intrinsic resistance without point mutation of ABL kinase domain are not fully understood. Moreover, ABL TKIs cannot cure the Ph-positive leukemia patients because of leukemia stem cells in the bone marrow niche. Therefore, new approach against leukemia stem cells may improve the outcome of Ph-positive leukemia patients. Hypoxia is an important component of the bone marrow microenvironment. Because oxygen tension plays a key role in driving normal hematopoiesis, leukemia stem cells may be maintained in hypoxic areas of the bone marrow. Materials and methods: In this study, we established ABL TKI-resistant in vitro cell line models (K562 imatinib-R, K562 nilotinib-R, K562 dasatinib-R, K562 ponatinib-R and Ba/F3 T315I). We investigated gene expression profiles in cultured ABL TKI resistant cells and parental cell line, K562 in normoxia and hypoxia condition by DNA microarray. Results: We first investigated gene expression profiles in cultured K562 cells in hypoxia condition. We found gene expression of insulin-like growth factor 1 (IGF1) was increased K562 cells in hypoxia condition by DNA microarray. We next examined ABL TKI resistant cell lines (K562 imatinib-R, K562 nilotinib-R, K562 dasatinib-R, K562 ponatinib-R) in this study. We could not detect the BCR-ABL point mutation in ABL TKI resistant cells. We found gene expression of insulin-like growth factor 1 (IGF1) receptor (IGF1R) was increased ABL TKI resistant K562 cells. IGF1R gene amplification was confirmed by RT-PCR analysis. IGF is tightly regulated by six related IGF-binding proteins (IGFBPs). One of IGFBP, IGFBP5 is related to imatinib sensitivity and resistant in chronic myeloid leukemia (CML) patients (GSE12211). In hypoxia condition, several IGFBPs were also increased in ABL TKI resistant cells. IGF cause intracellular signaling that ultimately results in cellular growth and proliferation. Thus, we initially examined whether addition of IGF1R inhibition could enhance ABL TKIs sensitivity. One of IGF1R inhibitor, linsitinib was inhibited ABL TKI resistant cells and parental cell line, K562 in hypoxia condition. ABL TKI resistant cell lines were more sensitive against linsitinib. Combined treatment of ABL TKI resistant cells and K562 cells with ABL TKIs and linsitinib caused more cytotoxicity than each drug alone in hypoxia condition. Caspase 3/7 activity and cellular cytotoxicity was also increased after ABL TKIs and linsitnib treatment. In the colony formation method, the number of cell colonies were also reduced in hypoxia condition. Intracellular ATP levels have been implicated in vitro as a determinant of cell death by apoptosis. The concentrations of intracellular ATP were reduced after ABL TKIs and linsitinib. We next blocked IGF1R function by small interfering RNA (siRNA). SiRNA transfected cells were reduced cellular proliferation. We also found drug sensitivity of the cells to the imatinib was increased compared to mock-transfected cells. Apoptotic cells and caspase 3/7 activity were increased after imatinib treatment in siRNA transfected cells. Conclusion: The IGF1 pathway is involved in Ph-positive leukemia cells in hypoxia condition and ABL TKI resistant in CML cells. We also provide the promising clinical relevance as a candidate drug for treatment of residual leukemia cells in bone marrow niche which is in hypoxia condition. Disclosures No relevant conflicts of interest to declare.

Screening and Identifying of the Protein Tyrosine Phosphatase Superfamily Members Related to Chronic Myeloid Leukemia and Exploration of Its Potential Function.

Blood ◽  
2006 ◽  
Vol 108 (11) ◽  
pp. 4296-4296
Author(s):  
Qingfeng Du ◽  
Song Zhang ◽  
Rong Li ◽  
Junmei Gong ◽  
Hongqian Zhu ◽  
...  
Keyword(s):  
Chronic Myeloid Leukemia ◽  
Mrna Expression ◽  
Differential Expression ◽  
Potential Function ◽  
Normal Control ◽  
Cdna Microarray ◽  
Myeloid Leukemia ◽  
K562 Cells ◽  
Rt Pcr ◽  
Protein Tyrosine

Abstract Chronic myeloid leukemia (CML) is characterized by formation of a BCR-ABL fusion gene, which encodes a chimeric protein, P210BCR-ABL. The protein tyrosine kinase(PTK) activity of P210BCR-ABL is aberrantly regulated and lead to catalyzes the phosphorylation of tyrosine residues in specific sites of P210BCR-ABL itself and a host of substrates, which is considered as the sufficient and necessary factor in the pathogenesis of CML. Current studies suggest that the tyrosine phosphorylation is a reversible dynamic procedure which is governed by the coordinated and competing actions of PTK and protein tyrosine phosphatases(PTP). As the balance between PTK and PTP are broken by P210BCR-ABL in CML, we assume that some responsive regulations must been done by the cells in order to antagonize the impact of PTK activity of P210BCR-ABL. Among those regulations, the changes at the transcriptional level of many important genes including PTP will be most direct and efficient. In order to screen and identify PTP related to CML and explore its potential function, we firstly induced apoptosis of K562 cells with STI571 and analyze the differential expression of PTP with BioStarH40s expression profile cDNA array. Among the 21 PTP included in the BioStarH40s cDNA microarray, 2 PTP, FAP1(NM_006264, ration=2.417) and SHP1(M77273, ration=5.012) showed differential expression. The results of cDNA microarray confirmed by semi-quantitative RT-PCR suggested that FAP1and SHP1 may involve the apoptotic signal transduction pathway triggered by STI571. Secondly, the mRNA level of SHP1 in CML was analyzed with semi-quantitative RT-PCR. The results detected that the mRNA expression level of SHP1 in CML-CP (7 cases) show no statistic difference with normal control. But in contrast, the mRNA expression had down-regulated in CML-BC(4 cases) and show significant difference with normal control. Furthermore, we cloned the full length cDNA sequence of SHP1 with RT-PCR and sub-cloned it into the mammalian expression vector pcDNA3.0. The orientation and the sequence of pcDNA3-SHP1 were further validated by restrictive enzyme digestion analysis and DNA sequence analysis. Thirdly, the potential functions of the SHP1, such as triggering apoptosis and inducing differentiation, were explored by over-expressing the candidate gene in K562 cells with lipofectin transfection technique. The results showed that over-expression of SHP1 in K562 cells is sufficient for inducing apoptosis and erythroid differentiation that may be strengthened by the additional of STI571 treatment.

Specific MiRNA Silencing by Lentivirus Mediated Antagomir Expression in Chronic Myeloid Leukemia (CML) Cells.

Blood ◽  
2007 ◽  
Vol 110 (11) ◽  
pp. 1017-1017
Author(s):  
Michaela Scherr ◽  
Letizia Venturini ◽  
Karin Battmer ◽  
Michael Schaller-Schoenitz ◽  
Daniel Schaefer ◽  
...  
Keyword(s):  
Cell Proliferation ◽  
Chronic Myeloid Leukemia ◽  
Myeloid Leukemia ◽  
Mrna Translation ◽  
K562 Cells ◽  
Mature Mirnas ◽  
Dependent Manner ◽  
Aberrant Expression ◽  
Over Expression ◽  
Micro Rnas

Abstract Micro RNAs (miRNA) are small non-coding RNAs that regulate gene expression by specific hybridization to complementary sequences in the 3′ untranslated region of corresponding mRNAs. Concomitant recruitment of specific multi-protein complexes results either in inhibition of mRNA translation or mRNA degradation. miRNAs are processed in a regulated multi-step process from primary transcripts into mature miRNAs by cellular components which are also at least partially involved in the process of RNA interference (RNAi). Aberrant expression of specific miRNAs has recently been described in human lymphoma and leukemia. In particular, BCR-ABL and c-MYC dependent over-expression of the polycistronic and oncogenic miR-17-92 cluster (encoding miR-17, miR-18a, miR-19a, miR-20a, miR-19b, and miR-92) has been described in chronic myeloid leukemia (CML) cell lines, primary CD34+ cells from CML patients (Venturini et al. 2007), and in lung cancer. In BCR-ABL positive K562 cells, miR-17-92 encoded miRNAs repress luciferase activity in miRNA-specific reporter assays. In addition, lentivirus-mediated over-expression of miR-17-92 increases both cell proliferation and sensitivity to imatinib induced cell death. To analyse the function of individual miRNAs of the miR-17-92 polycistron, we generated lentivirus-based strategies to induce stable miRNA-specific loss- and gain-of function phenotypes for miR-18a, miR-19b, and miR-20a, respectively. Over-expression of miRNAs embedded within miR-30-derived sequences from an internal SFFV-LTR promoter allows isolation of K562 cells with increased miRNA expression. In contrast, expression of complementary oligonucleotides (antagomirs) from a H1 promoter located in the lentiviral 3′LTR can induce stable hypomorphic miRNA-phenotypes. In lentivirally transduced K562 cells, individual silencing of miR-18a, miR-19b, and miR-20a by the corresponding antagomirs (ant-miR-18a, ant-miR-19b, ant-miR-20a) specifically relieves miRNA-mediated reporter gene repression. Correspondingly, inhibition of miRNA-function correlates to reduced ‘miRNA’-amplification by miRNA-specific quantitative RT-PCR. Furthermore, protein expression of E2F-1, a known miR-20 target, is enhanced by lentivirally expressed anti-miR-20 in a dose-dependent manner, whereas over-expression of miR-20a reduces E2F-1 levels. Finally, combined over-expression of specific miRNAs and antagomirs reveals specific induction of cell proliferation by miR-18a but strong inhibition by miR-20a in K562 cells, respectively. In contrast, anti-miR-18a, but not anti-miR-19b, anti-miR-20a, or control antagomirs inhibits proliferation of K562 cells. These data demonstrate individual and complementary functions of miR-17-92 encoded miRNAs in CML and identify potential targets for specific therapeutic intervention on the miRNA level.

Quantitative Phosphoproteomics Identified a New Syk-Lyn-Axl Signalling Pathway Involved In Resistance to Nilotinib In Chronic Myeloid Leukemia Cells.

Blood ◽  
2010 ◽  
Vol 116 (21) ◽  
pp. 3376-3376
Author(s):  
Romain Gioia ◽  
Cedric Leroy ◽  
Claire Drullion ◽  
Valérie Lagarde ◽  
Serge Roche ◽  
...  
Keyword(s):  
Chronic Myeloid Leukemia ◽  
Tyrosine Kinase ◽  
Myeloid Leukemia ◽  
Conflicts Of Interest ◽  
Critical Role ◽  
Dependent Manner ◽  
Stable Isotope Labelling ◽  
Resistant Cells

Abstract Abstract 3376 Nilotinib has been developed to overcome resistance to imatinib, the first line treatment of chronic myeloid leukemia (CML). To anticipate resistance to nilotinib, we generate nilotinib resistant CML cell lines in vitro to characterize mechanisms and signaling pathways that may contribute to resistance. Among the different mechanisms of resistance identified, the overexpression of the Src-kinase Lyn was involved in resistance both in vitro, in a K562 cell line (K562-rn), and in vivo, in nilotinib-resistant CML patients. To characterize how Lyn mediates resistance, we performed a phosphoproteomic study using SILAC (Stable Isotope Labelling with Amino acid in Cell culture). Quantification and identification of phosphotyrosine proteins in the nilotinib resistant cells point out two tyrosine kinases, the spleen tyrosine kinase Syk and the UFO receptor Axl. The two tyrosine kinase Syk and Axl interact with Lyn as seen by coimmunopreciptation. Syk is phosphorylated on tyrosine 323 and 525/526 in Lyn dependent manner in nilotinib resistant cells. The inhibition of Syk tyrosine kinase by R406 or BAY31-6606 restores sensitivity to nilotinib in K562-rn cells. In parallel, the inhibition of Syk expression by ShRNA in K562-rn cells abolishes Lyn and Axl phosphorylation and then interaction between Lyn and Axl leading to a full restoration of nilotinib efficacy. In the opposite, the coexpression of Lyn and Syk in nilotinib sensitive K562 cells induced resistance to nilotinib whereas a Syk kinase dead mutant did not. These results highlight for the first time the critical role of Syk in resistance to tyrosine kinase inhibitors in CML disease emphasizing the therapeutic targeting of this tyrosine kinase. Moreover, Axl, which is already a target in solid tumor, will be also an interesting pathway to target in CML. Disclosures: No relevant conflicts of interest to declare.

Proliferation Inhibition and Apoptosis Induction Of Imatinib Resistance Chronic Myeloid Leukemia Cells By Down-Regulated PPP2R5C

Blood ◽  
2013 ◽  
Vol 122 (21) ◽  
pp. 5158-5158
Author(s):  
Qi Shen ◽  
Sichu Liu ◽  
Yu Chen ◽  
Lijian Yang ◽  
Shaohua Chen ◽  
...  
Keyword(s):  
Gene Expression ◽  
Chronic Myeloid Leukemia ◽  
Cell Lines ◽  
Myeloid Leukemia ◽  
Primary Cells ◽  
Healthy Individuals ◽  
Hoechst 33258 ◽  
Imatinib Resistance ◽  
Imatinib Resistant

Abstract Chronic myeloid leukemia (CML) is a hematopoietic stem cell disorder that occurs because of t(9;22)(q34;q11) translocations. The prognosis in CML improved markedly after introduction of abl tyrosine kinase inhibitors (TKI), still a lot of CML patients die due to abl mutation related drug resistance and the blast crisis, moreover, de novo or secondary TKI-resistance is a significant problem in CML. The aim of the study is to down-regulate the PPP2R5C gene expression in imatinib-sensitive or imatinib-resistant chronic myeloid leukemia (CML) cell lines: K562, K562R (imatinib resistance without abl gene mutation), 32D-Bcr-Abl WT (imatinib sensitive, murine CML cell lines with wild type abl gene) and 32D-Bcr-Abl T315I (imatinib resistance, with abl gene T315I mutation) and primary cells from CML patients by RNA interference, thereby inhibit the CML cells proliferation and induce apoptosis. PPP2R5C-siRNAs numbered 799 or 991 were obtained by chemosynthesis. Non-silencing siRNA control (SC)-treated, mock-transfected, untreated cells were used as controls. PPP2R5C expression in mRNA levels from CML cells were analyzed after siRNAs delivered by nucleofection using the real-time quantitative PCR. The PPP2R5C protein levels were analyzed by Western blotting. Cell proliferation in vitro was assayed by the cell count kit-8 method after treatment. The morphology and the percentage of apoptosis were revealed by Hoechst 33258 stain and flow cytometry (FCM). Bone marrow mononuclear cells (BM-MNCs) from healthy individuals were transferred by PPP2R5C-siRNA-991. BFU-E, CFU-Meg and CFU-GM were performed from PPP2R5C-siRNA-991 treated BM-MNCs by methyl cellulose semi-solid culturing method, to estimate the role of differentiation and proliferation in BM-MNCs after PPP2R5C-siRNA transfection. The results showed that both PPP2R5C-siRNA-799 and PPP2R5C-siRNA-991 took best silencing results after nucleofection in all of four cells and primary cells from CML patients. The reduction about 2 to 7 folds in PPP2R5C mRNA level was observed in PPP2R5C-siRNA799 or PPP2R5C-siRNA991 treated cells. And PPP2R5C protein expression inhibition rate reached 38.08%-55.26% at 48 or 72 h after treatment. The proliferation rates of PPP2R5C-siRNA-799 or 991 treated CML cells were significantly decreased at 72 h (P < 0.05). PPP2R5C-siRNA-799 or 991 treated CML cells lines showed a significantly increase in AnnexinV/PI-positive cells (apoptosis) (P < 0.05), similar results in the morphological changes of apoptosis were found by Hoechst 33258 staining test. PPP2R5C gene mRNA expression levels in BM-MNCs from healthy individuals were significantly lower than that in K562 cells (P < 0.05), and the expression level was not significant changed after PPP2R5C-siRNA-991 transfection. The formation of BFU-E, CFU-Meg and CFU-GM from BM-MNCs showed no significant difference between PPP2R5C-siRNA-991 treatment and MOCK control group (P > 0.05). In conclusions, suppression of PPP2R5C by RNA interference could inhibit the proliferation and induce the apoptosis effectively in CML cells either in imatinib sensitive or imatinib resistance cell lines, while no significant effect of PPP2R5C-siRNA on the proliferation and differentiation of BM-MNCs in vitro, suggesting that PPP2R5C-siRNA might specially target on the CML cells. Down-regulating the PPP2R5C gene expression might be considered as a new target therapeutic strategy in CML, especially in imatinib-resistant CML. Disclosures: Li: This work was supported by Grants from National Natural Science Foundation of China (30871091 and 91129720), the Collaborated grant for HK-Macao-TW of Ministry of Science and Technology (2012DFH30060), the Guangdong Science & Technology Project (2012B0506: Research Funding.

scholarly journals Orlistatand and Rosuvastatin Suppressed Proliferation of K562 Human Myelogenous Leukemia Cell Line through AMPK/Akt/c-Myc Signaling

2020 ◽  
Author(s):  
Behnam Mojjarad ◽  
Yaghub Pazhang
Keyword(s):  
Cell Cycle ◽  
Chronic Myeloid Leukemia ◽  
Cell Line ◽  
Myeloid Leukemia ◽  
Leukemia Cell ◽  
K562 Cells ◽  
Myelogenous Leukemia ◽  
Leukemia Cell Line ◽  
Mrna Levels ◽  
Hsp 70

Abstract Background: Chronic myeloid leukemia is a myeloproliferative cancer with worldwide incidence, has become as a clinical concern due to chemoresistance in the patients received chemotherapy. Here, we investigated the effect of Orlistat and Rosuvastatin on K562 human myelogenous leukemia cell line in vitro and attempted to illuminate their possible underlying mechanisms. Methods: Cells were exposed to Orlistat and Rosuvastatin, the inhibitors of lipogenesis, then survival and apoptosis rate of K562 cells were examined by MTT assay and flow cytometric analysis respectively. The real time-PCR analysis was used to quantify mRNA levels of Bax, Bcl-2, and Hsp-70 genes. Cell cycle analysis was performed using flow cytometry, whereas the subcellular distribution of c-Myc was measured via immunofluorescence imaging technique. Additionally, the protein level of AMPK, p-AMPK Akt-1, and p-Akt-1 were studied by western blotting. Results: The results showed Orlistat and Rosuvastatin had synergistic anticancer effects on cells and in comparison with the control group, viability and apoptosis rate decreased and increased in treated cells respectively in a dose/time-dependent manner (P<0.05). The mRNA levels of Bax increased while expression of Hsp-70 decreased (P< 0.05). K562 cells treated with Orlistat and Rosuvastatin showed a cell cycle arrest in sub-G1 phase and a decreased level of c-Myc positive cells. Upon outlining the mechanism, it was revealed that AMPK/p-AMPK and p-Akt-1/Akt-1 ratio decreased in treated cells (P< 0.05). Conclusions: Data suggest Orlistat and Rosuvastatin could synergically suppress proliferation of K562 cells through AMPK/Akt/c-Myc axis, proposing a theoretical basis for upcoming application in the treatment of chronic myeloid leukemia

scholarly journals ENOX2 NADH Oxidase: A BCR-ABL1-dependent cell surface and secreted redox protein in chronic myeloid leukemia (CML)

2021 ◽  
Author(s):  
Seda Baykal-Köse ◽  
Maud Voldoire ◽  
Christophe Desterke ◽  
Nathalie Sorel ◽  
Emilie Cayssials ◽  
...  
Keyword(s):  
Chronic Myeloid Leukemia ◽  
Mrna Expression ◽  
Cell Lines ◽  
Myeloid Leukemia ◽  
Myeloproliferative Neoplasm ◽  
Chronic Phase ◽  
Dependent Manner ◽  
Western Blots ◽  
Hematopoietic Stem ◽  
Redox Protein

AbstractChronic myeloid leukemia (CML) is a myeloproliferative neoplasm caused by the acquisition of BCR-ABL1 fusion in a hematopoietic stem cell. We identified the ENOX2 gene as up-regulated in BCR-ABL1-expressing UT-7 cell lines through a transcriptome assay. The oncofoetal ENOX2 protein (Ecto-Nicotinamide Adenine Dinucleotide Oxidase Disulfide Thiol Exchanger 2) is expressed on the external plasma membrane surface of cancer cells and can be released in cancer patients’ serum. Considering these data, we studied ENOX2 expression in CML cell lines and patients using quantitative RT-PCR, western-blots, the ELISA method, and transcriptomic dataset reanalysis. We confirmed increased ENOX2 mRNA expression in the BCR-ABL1-expressing UT-7 cell line. Comparable results were obtained in CML patients at diagnosis. Western-blot analyses on UT-7 and TET-inducible Ba/F3 cell lines established the up-regulation of ENOX2 protein. BCR-ABL1 has been found to induce ENOX2 overexpression in a kinase-dependent manner. In a series of 41 patients with CML, ELISA assays showed a highly significant increase of ENOX2 protein levels in the plasma of patients with CML (p < 0.0001) as compared to controls (n=28). Transcriptomic dataset (GSE4170) reanalyzes have shown specific ENOX2 mRNA overexpression in the chronic phase of the disease. Bioinformatic analyses identified several genes whose mRNA expression was positively correlated to ENOX2. Some of them encode proteins involved in cellular functions compatible with the growth deregulation observed in CML. All in all, our results demonstrate for the first time the upregulation of a secreted Redox protein in a BCR-ABL1-dependent manner in CML. Our data suggest that ENOX2 (through its transcriptional program) plays a significant role in the BCR-ABL1 leukemogenesis. Further studies are required to clarify the relationship between BCR-ABL1 and ENOX2.

Synergic Effects of Proteasome Inhibitor PS-341 and Tyrosine Kinase Inhibitor STI571 on Chronic Myeloid Leukemia Cells and BCR-ABL Oncoprotein In Vitro and In Vivo.

Blood ◽  
2006 ◽  
Vol 108 (11) ◽  
pp. 4771-4771
Author(s):  
Guangbiao Zhou ◽  
Zheng Hu ◽  
Dapeng Liu ◽  
Fuqun Wu ◽  
Jiang Zhu ◽  
...  
Keyword(s):  
Chronic Myeloid Leukemia ◽  
Tumor Growth ◽  
Proteasome Inhibitor ◽  
Myeloid Leukemia ◽  
K562 Cells ◽  
Leukemic Cells ◽  
Great Promise ◽  
Dependent Manner

Abstract STI571/Gleevec/imatinib, a rationally-designed agent that occupies the ATP-binding site of BCR-ABL and stabilizes the protein in its closed, inactive conformation, has been a remarkable success for the treatment of chronic myeloid leukemia (CML). However, a significant proportion of patients chronically treated with STI571 develop resistance because of the acquisition of mutations in the kinase domain of BCR-ABL. Furthermore, the effects of STI571 on CML patients in accelerated phase or blastic crisis are unsatisfactory since many patients relapse after transient remission. Hence, additional drugs or STI571-based combination regimens are desired to circumvent resistance and to improve response rates. Here we reported that PS-341, a proteasome inhibitor which offers great promise to patients with multiple myeloma (MM), significantly enhanced the antileukemia activity of STI571 in vitro and in vivo. We found a synergy exists between low concentrations of PS-341 (5–10 nM) and STI571 (0.1–0.2 μM) in inhibition of cell growth and induction of apoptosis in K562 cell line and CD34+ leukemic cells isolated from CML patients. In K562 cells, combined use of PS-341 and STI571 accelerated activation of caspase-3, 9, and facilitated cleavage of poly-(ADP-ribose) polymerase (PARP) as compared to those in cells treated with PS-341 or STI571 alone. Moreover, PS-341/STI571 combination resulted in potentiated degradation of BCR-ABL and downregulation of phosphorylated BCR-ABL as compared to those in mono treatment. In nude mice inoculated subcutaneously with K562 cells, treatment with PS-341 (injected intraperitoneally, ip) alone (at doses of 0.05, 0.5, 1 mg/kg/d, twice a week for 4 weeks, respectively) decreased tumor growth in a dose-dependent manner. STI571 (ip) at 10 mg/kg/d also inhibited tumor growth. Intriguingly, combinatory administration of low dose PS-341 (0.05 mg/kg/d, twice a week for 4 weeks) and STI571 (10 mg/kg/d) yielded a much more profound inhibition of tumor growth and even clearance of leukemic cells in mice compared to either monotherapy. Taken together, these results demonstrate synergic effects of PS-341 and STI571, and provide the rationale to evaluate PS-341/STI571 combination in treating CML aiming to further improve clinical outcome of patients.

Preliminary Study On Influence of Imatinib-Induced Apoptosis in Chronic Myeloid Leukemia Cells Co-Culture with Fibronectin Adhesion.

Blood ◽  
2009 ◽  
Vol 114 (22) ◽  
pp. 4264-4264
Author(s):  
Liu Xiaoli ◽  
Na Xu ◽  
Qingfeng Du ◽  
Zhi Liu ◽  
Rong Li ◽  
...  
Keyword(s):  
Monoclonal Antibody ◽  
Bone Marrow ◽  
Chronic Myeloid Leukemia ◽  
Growth Inhibition ◽  
Myeloid Leukemia ◽  
K562 Cells ◽  
Bone Marrow Microenvironment ◽  
Dependent Manner ◽  
Imatinib Resistance ◽  
Significant Difference

Abstract Abstract 4264 The bone marrow microenvironment supports growth, differentiation and proliferation of normal hematopoietic cells and can also contribute to malignant growth. Recently,it is considered that except for the point mutant of BCR-ABL kinase contribute to imatinib-resistant therapy for patients with chronic myeloid leukemia(CML), environment-mediated drug resistance (EM-DR) is a potential factor in imatinib resistance. Our previous studies found that Integrin, focal adhesion kinase(FAK), RhoA(a small GTPase) are important adhesion molecules,and related to imatinib resistance. But how and what they crosstalk with each other is still open to debate. In order to simulated bone marrow microenvironment, we used the major components of bone marrow microenvironment- Fibronectin (Fn) co-cultured with human leukemia K562 cells.and then K562 cells were inoculated with Fn, collagen-coated plate(Co) and suspended cultures as control(mask) group,and then treated with 0.4μM,0.8μM,1.6μM,3.2μM,6.4μM imatinib for 24h,48h and 72h, detected cell apoptosis and proliferation by MTT and AnnexinV-PI assay, examined p-FAK and Rho-GTP by Wersten Blotting and Pull down-Wersten Blotting. The data showed that compared to the Co and mask groups, the cells growth inhibition and apoptosis in Fn co-culture group was significantly reduced. The protein expression of p-FAK and Rho-GTP was higher in the Fn group,and in time-dependent manner. When K562 cells in Fn group were transfected with 150nM siRNA-RhoA for 48h, there was no significant difference compared with the Co and mask groups. Furthermore, the above groups treated with anti-integrin monoclonal antibody (anti-CD29 mAb), we found that p-FAK was significant lower compared with without anti-CD29 mAb in the Fn group; but there was no significant difference of Rho-GTP compard with without anti-CD29 mAb in Fn group. These results indicate that Fn adhesion co-culture could reduce imatinib-induced cell growth inhibition and apoptosis, and this mechanism may be correlated to Rho-GTP activity,and anti-integrin monoclonal antibody could not completely block the integrin binding to Fn on K562 cells, or there was other pathway activated RhoA. The mechanism of EM-DR is complex,and which is well worth us to speculate and study. Disclosures: No relevant conflicts of interest to declare.

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