Interferon-γ (IFN-γ) has been used to control cancers in clinical treatment. However, an increasing number of reports have suggested that in some cases effectiveness declines after a long treatment period, the reason being unclear. We have reported previously that long-term IFN-γ treatment induces malignant transformation of healthy lactating bovine mammary epithelial cells (BMECs) in vitro. In this study, we investigated the mechanisms underlying the malignant proliferation of BMECs under IFN-γ treatment. The primary BMECs used in this study were stimulated by IFN-γ (10 ng/mL) for a long term to promote malignancy. We observed that IFN-γ could promote malignant cell proliferation, increase the expression of cyclin D1/cyclin-dependent kinase 4 (CDK4), decrease the expression of p21, and upregulate the expression of cellular-abelsongene (c-Abl) and histone deacetylase 2 (HDAC2). The HDAC2 inhibitor, valproate (VPA) and the c-Abl inhibitor, imatinib, lowered the expression level of cyclin D1/CDK4, and increased the expression level of p21, leading to an inhibitory effect on IFN-γ-induced malignant cell growth. When c-Abl was downregulated, the HDAC2 level was also decreased by promoted proteasome degradation. These data suggest that IFN-γ promotes the growth of malignant BMECs through the c-Abl/HDAC2 signaling pathway. Our findings suggest that long-term application of IFN-γ may be closely associated with the promotion of cell growth and even the carcinogenesis of breast cancer.
Animals ; Carcinogenesis/pathology* ; Cattle ; Cell Cycle Proteins/metabolism* ; Cell Proliferation/drug effects* ; Cell Transformation, Neoplastic/pathology* ; Cells, Cultured ; Epithelial Cells/pathology* ; Female ; Histone Deacetylase 2/metabolism* ; Imatinib Mesylate/pharmacology* ; Interferon-gamma/pharmacology* ; Mammary Glands, Animal/pathology* ; Mammary Neoplasms, Experimental/pathology* ; Proto-Oncogene Proteins c-abl/metabolism* ; Signal Transduction ; Valproic Acid/pharmacology*

This study was aimed to investigate the effect of SU11248 on proliferation and apoptosis of leukemia cell line K562 in vitro and its mechanism. The inhibitory effect of 3.2 µg/ml SU11248 on K562 proliferation was tested by MTT assay. The ability of SU11248 to induce apoptosis of K562 cells was examined by TUNEL and DNA ladder. The expression of C-MYC, hTERT and BCR-ABL mRNA in K562 cells was detected by RT-PCR. The protein expression of Akt and p-Akt in K562 cells was detected by Western blot. The results showed that the proliferation of K562 cells was obviously inhibited by 3.2 µg/ml SU11248 in a time-dependent manner. SU11248 could induce K562 cells apoptosis in dose-and time-dependent manner. The mRNA expression of C-MYC, hTERT and BCR-ABL was reduced significantly by SU11248 in a time-dependent manner (P < 0.05). Western blot detection showed that the expression of p-Akt protein in K562 cells decreased in dose-and time-dependent manner after SU11248 treatment, but the expression of Akt was not significantly changed. It is concluded that SU11248 can inhibit the growth of K562 cells efficiently through inducing apoptosis, its mechanism may be closely relate with the expression down-regulation of C-MYC, hTERT, BCR-ABL and the inhibition of Akt phosphorylation.
Apoptosis ; drug effects ; Cell Proliferation ; drug effects ; Fusion Proteins, bcr-abl ; metabolism ; Humans ; Indoles ; pharmacology ; K562 Cells ; Proto-Oncogene Proteins c-akt ; metabolism ; Proto-Oncogene Proteins c-myc ; metabolism ; Pyrroles ; pharmacology ; RNA, Messenger ; genetics ; Telomerase ; metabolism

OBJECTIVETo explore the inhibitory effect of alantolactone on the proliferation of adriamycin-resistant human chronic myelogenous leukemia cell line K562/ADR cells and its mechanism.

METHODSK562/ADR cells were treated with various concentrations of alantolactone (0, 1, 2, 4, 6, 8, and 10 μmol/L) for different time points. Cell viability was analyzed with MTT assay. The effect of alantolactone on the apoptosis of K562/ADR cells was measured by flow cytometry. The expression of apoptosis-related proteins after treatment with alantolactone was analyzed using Western blot.

RESULTSAlantolactone could effectively inhibit the proliferation of K562/ADR cells in dose- and time- dependent manner, the IC50 value of alantolactone treatment of K562/ADR cells for 24 h was 4.7 μmol/L (P<0.05). Flow cytometric analysis displayed that the apoptotic rates were 1.35%, 16.91%, 29.61% and 46.26%, respectively, after treatment with alantolactone at 0, 2.5, 5 and 7.5 μmol/L. Meanwhile, the expression of Bcl-2 and BCR-ABL proteins were significantly decreased and that of Bax, cytochrome C, cleaved-caspase-9, cleaved-caspase-3 and cleaved-PARP increased by alantolactone treatment.

CONCLUSIONAlantolactone had obvious inhibitory effect on the proliferation of K562/ADR cells through the caspase dependent mitochondrial(or intrinsic)apoptotic pathway.

Apoptosis ; Caspase 3 ; metabolism ; Caspase 9 ; metabolism ; Cell Proliferation ; drug effects ; Fusion Proteins, bcr-abl ; metabolism ; Humans ; K562 Cells ; Lactones ; pharmacology ; Proto-Oncogene Proteins c-bcl-2 ; metabolism ; Sesquiterpenes, Eudesmane ; pharmacology ; bcl-2-Associated X Protein ; metabolism

Humans ; Leukemia, Myelogenous, Chronic, BCR-ABL Positive ; metabolism ; Proto-Oncogene Proteins c-akt ; metabolism ; Signal Transduction

Studies on chronic myeloid leukemia (CML) have served as a paradigm for cancer research and therapy. These studies involve the identification of the first cancer-associated chromosomal abnormality and the subsequent development of tyrosine kinase inhibitors (TKIs) that inhibit BCR-ABL kinase activity in CML. It becomes clear that leukemia stem cells (LSCs) in CML which are resistant to TKIs, and eradication of LSCs appears to be extremely difficult. Therefore, one of the major issues in current CML biology is to understand the biology of LSCs and to investigate why LSCs are insensitive to TKI monotherapy for developing curative therapeutic strategies. Studies from our group and others have revealed that CML LSCs form a hierarchy similar to that seen in normal hematopoiesis, in which a rare stem cell population with limitless self-renewal potential gives rise to progenies that lack such potential. LSCs also possess biological features that are different from those of normal hematopoietic stem cells (HSCs) and are critical for their malignant characteristics. In this review, we summarize the latest progress in CML field, and attempt to understand the molecular mechanisms of survival regulation of LSCs.
Animals ; DNA-Binding Proteins ; genetics ; metabolism ; Fusion Proteins, bcr-abl ; antagonists & inhibitors ; metabolism ; Humans ; Hypoxia-Inducible Factor 1 ; metabolism ; Leukemia, Myelogenous, Chronic, BCR-ABL Positive ; drug therapy ; metabolism ; pathology ; Lipid Metabolism ; Neoplastic Stem Cells ; drug effects ; metabolism ; Protein Kinase Inhibitors ; pharmacology ; therapeutic use ; Proto-Oncogene Proteins c-bcl-6 ; src-Family Kinases ; metabolism

The aim of this study was to investigate the effect of suppression of nicotinamide phosphoribosyltransferase (NAMPT) expression on imatinib-sensitivity in chronic myelogenous leukemia (CML) cell line K562 and its mechanisms, NAMPT siRNA was synthesized and transfected into K562 cells. PI/Calcein staining technique was used to determine survival rate of transfected K562 cells at 48th hour after exposure to 1 µmol/L imatinib. MTS method was used to determine the proliferation changes of transfected K562 cell at 48th hour after exposure to different doses of imatinib, then half inhibitory concentration (IC(50)) was calculated. Expression of NAMPT at 3rd-48th hour after exposure to 1 µmol/L imatinib was determined by Western blot. To explore the effect of NAMPT-siRNA and imatinib on the expression of apoptosis-related genes, the microarray data from NCBI GEO Data-Sets was analyzed, then the results were confirmed by Western blot. The luciferase reporter assay was used to determine the effect of NAMPT and imatinib on transcriptional activity of NF-κB transcription factors. The results showed that after exposure to 1 µmol/L imatinib for 3 - 48 h, there was no significant change of NAMPT expression in K562 cells. The expression of NAMPT could be effectively inhibited by the NAMPT-siRNA. After exposure to 1 µmol/L of imatinib for 48 h, the survival rate of NAMPT-siRNA interference group was lower than that of negative control group (P < 0.05), indicating that suppression of NAMPT expression can increase the sensitivity of K562 cells to imatinib and enhance the killing effect of imatinib on K562 cells. The IC(50) of imatinib in NAMPT-siRNA interference group was the lowest compared with that of control group (P < 0.05) after exposure to different concentrations of imatinib for 48 h, the fitted survival curves showed that the slope of NAMPT-siRNA interference group was the largest ranging between 0.01 - 0.1 µmol/L of imatinib. Data mining of expression profiling indicated that the anti-apoptotic factor Bcl-2 decreased in K562 cells treated with either NAMPT-siRNA or imatinib, which was confirmed by Western blot. The inhibitory effect was much more significant when both NAMPT-siRNA and imatinib were used. The results of luciferase reporter assay showed that either NAMPT-siRNA or imatinib decreased transcriptional activity of NF-κB. The decreased effect was much more significant when both NAMPT-siRNA and imatinib were used. It is concluded that survival of K562 cells affected by imatinib may not be due to regulation of expression of NAMPT. When expression of NAMPT decreases, the K562 cells are more sensitive to imatinib, this may be related with the decreased transcriptional activity of NF-κB and its downstream effector Bcl-2.
Benzamides ; Cytokines ; antagonists & inhibitors ; metabolism ; Fusion Proteins, bcr-abl ; metabolism ; Humans ; Imatinib Mesylate ; K562 Cells ; NF-kappa B ; metabolism ; Nicotinamide Phosphoribosyltransferase ; antagonists & inhibitors ; metabolism ; Piperazines ; pharmacology ; Proto-Oncogene Proteins c-bcl-2 ; metabolism ; Pyrimidines ; pharmacology

Imatinib mesylate has been commonly used in the treatment of patients with chronic myeloid leukemia (CML). However, a significant number of CML patients treated with imatinib developed thrombocytopenia. Platelet-derived growth factor (PDGF)/platelet-derived growth factor receptor (PDGFR) plays a significant role in the regulation of thrombopoiesis. It is suggested that imatinib may block the PDGF/PDGFR and PI3-K/Akt pathway, then inducing the apoptosis of megakaryocytes and developing thrombocytopenia in these patients. In this review, the potential molecular mechanism of imatinib-induced thrombocytopenia in the treatment of CML patients is discussed, including imatinib and thrombocytopenia, PDGF/PDGFR and thrombopoiesis, potential mechanism of imatinib-induced thrombocytopenia in treatment of patients with CML and so on.
Antineoplastic Agents ; adverse effects ; therapeutic use ; Benzamides ; Caspase 3 ; metabolism ; Humans ; Imatinib Mesylate ; Leukemia, Myelogenous, Chronic, BCR-ABL Positive ; drug therapy ; genetics ; metabolism ; Piperazines ; adverse effects ; therapeutic use ; Platelet-Derived Growth Factor ; metabolism ; Proto-Oncogene Proteins c-akt ; metabolism ; Pyrimidines ; adverse effects ; therapeutic use ; Signal Transduction ; Thrombocytopenia ; chemically induced ; Thrombopoiesis

The aim of this study was to investigate the apoptosis-inducing effect of anti-CD44 monoclonal antibody IM7 on chronic myeloid leukemia (CML) stem/progenitor cells in vitro and to explore its possible mechanism. Leukemic stem/progenitor cells (LSPCs) expressing CD34(+), CD38(-) and CD123(+) were isolated from bone marrow (BM) cells of 20 patients with newly-diagnosed chronic myeloid leukemia by using EasySep(TM) magnetic beads. The percentage of apoptotic CML-LSPCs was assayed by Annexin-V/PI staining; the expression changes of c-myc and NF-kappaB mRNA were detected by real-time quantitative PCR (RQ-PCR) and RT-PCR; the NF-kappaB activity was detected by NF-kappaB Activation Nuclear Translocation Assay Kit; the BCL-2 protein expression was determined in the Western blot method. The results showed that the IM7 effectively induced apoptosis of CML-LSPCs; the mean percentage of early apoptotic cells significantly increased, as compared with the untreated control CML-LSPCs cells 12.58 +/- 2.84% vs 5.42 +/- 1.84% (p < 0.05). The c-myc, NF-kappaB mRNA expressions were down-regulated as compared with the control group (0.65 +/- 0.10 vs 1.00, 0.42 +/- 0.21 vs 1.00, respectively) (p < 0.01) by RQ-PCR and (0.49 +/- 0.09 vs 0.60 +/- 0.12, 0.47 +/- 0.11 vs 0.67 +/- 0.08, respectively)(p < 0.01) by RT-PCR. The BCL-2 protein level in CML-LSPCs treated with IM7 also decreased as compared with the control group (p < 0.01). In addition, the depression of NF-kappaB activity was observed through fluorescence microscope. It is concluded that the anti-CD44 monoclonal antibody IM7 effectively induces apoptosis of CML-LSPCs through down-regulating c-myc and bcl-2 mRNA expression, and decreasing NF-kappaB activity in CML-LSPCs.
Antibodies, Monoclonal ; pharmacology ; Apoptosis ; drug effects ; genetics ; Humans ; Hyaluronan Receptors ; immunology ; Leukemia, Myelogenous, Chronic, BCR-ABL Positive ; genetics ; metabolism ; NF-kappa B ; metabolism ; Neoplastic Stem Cells ; drug effects ; Proto-Oncogene Proteins c-bcl-2 ; metabolism ; Proto-Oncogene Proteins c-myc ; metabolism ; Tumor Cells, Cultured

OBJECTIVETo investigate the effect of meisoindigo on bcr-abl signaling pathway and to explore the mechanism of meisoindigo inducing apoptosis in K562 cells.

METHODSApoptosis and mitochondria membrane potential (MMP) were evaluated by flow cytometry. In K562 cells, the expression level of Bcl-2 family members, cleaved caspase members, bcr-abl, STAT5 and CRKL were determined by Western blot and bcr-abl mRNA expression level was measured by RT-PCR before and after meisoindigo treatment. The DNA binding potential of STAT3 and STAT5 was checked by electronic mobility shift assay (EMSA).

RESULTSDown-regulation of total and phosphorylated bcr-abl protein level in K562 cells was observed when treated with 20 micromol/L meisoindigo, but its mRNA level was not changed. The expression level of phosphorylated STAT5 and CRKL was decreased and the DNA binding potential of STAT3 and STAT5 were inhibited in K562 cell after exposure to meisoindigo. Exposure to 5 - 20 micromol/L meisoindigo induced apoptosis accompanied with activating of caspase 3, 8, 9 and decreasing of MMP in K562 cells in a dose-dependent manner. The apoptosis was blocked by 50 micromol/L z-DEVD-fmk, z-IETD-cho, z-LETD-fmk, the specific inhibitors of caspase 3, 8, 9, respectively. No change in Bcl-2, Bax and Bid protein expression levels were observed before and after meisoindigo inducing apoptosis.

CONCLUSIONMeisoindigo can inhibit the proliferation of K562 cells by affecting the bcr-abl signaling transduction pathway. Meisoindigo induces K562 cell apoptosis through a novel caspase dependent pathway in addition to the contribution of mitochondria. The Bcl-2 family members are not involved in the apoptosis induction by meisoindigo in K562 cells.

Apoptosis ; drug effects ; Caspases ; metabolism ; Fusion Proteins, bcr-abl ; genetics ; metabolism ; Humans ; Indoles ; pharmacology ; K562 Cells ; Proto-Oncogene Proteins c-bcl-2 ; metabolism ; RNA, Messenger ; genetics ; STAT3 Transcription Factor ; metabolism ; STAT5 Transcription Factor ; metabolism ; Signal Transduction ; drug effects ; bcl-2-Associated X Protein ; metabolism

Chronic myelogenous leukemia (CML) is a clonal myeloproliferative disease of transformed hematopoietic progenitor cells. It is now clear that the chimeric bcr/abl P210(bcr/abl) fusion protein, which is generated by the reciprocal translocation t (9; 22), inhibits apoptosis and increase proliferation. P210(bcr/abl) plays a central role in the pathophysiology of CML. The purpose of this study was to construct a cell line model that bcr/abl expression can be regulated by Tet-off inducing-expression-system. The full-length b3a2 bcr/abl cDNA was subcloned into the pTRE2hyg expression vector to construct the pT2-P210 plasmid. 293 cells were firstly transfected with Tet-off plasmid and the clone that the Tet-off system can work effectively after transfected with pTRE2hyg-LUC was selected by luciferase activity assay. The pT2-P210 plasmid was then transfected into the selected clone and cells were then selected for hygromycin B and G418 resistance. The results showed that individual subclones expressing bcr/abl after withdrawing doxycycline were 293pT2-P210 cell line. In conclusion, selected 293pT2-P210 cells are cells that bcr/abl expression can be regulated by Tet-off inducing-expression-system. They are suitable thoroughly to study the function of bcr/abl fusion gene and its signal regulation mechanism.
Base Sequence ; Cell Line, Transformed ; cytology ; physiology ; Chromosomes, Human, Pair 22 ; genetics ; Chromosomes, Human, Pair 9 ; genetics ; Fusion Proteins, bcr-abl ; biosynthesis ; genetics ; Gene Expression Regulation, Neoplastic ; Genes, abl ; genetics ; Humans ; Leukemia, Myelogenous, Chronic, BCR-ABL Positive ; genetics ; metabolism ; pathology ; Models, Genetic ; Molecular Sequence Data ; Proto-Oncogene Proteins c-bcr ; genetics ; Transfection ; Translocation, Genetic ; Tumor Cells, Cultured