Dexamethasone promotes renal fibrosis by upregulating ILT4 expression in myeloid-derived suppressor cells.

Studies have shown that adoptive transfer of myeloid-derived suppressor cells (MDSCs) can alleviate various inflammatory diseases, including glomerulonephritis, but the long-term effects of the transferred MDSCs are still unclear. In addition, although glucocorticoids exert immunosuppressive effects on inflammatory diseases by inducing the expansion of MDSCs, the impact of glucocorticoids on the immunosuppressive function of MDSCs and their molecular mechanisms are unclear. In this study, we found that adoptive transfer of MDSCs to doxorubicin-induced focal segmental glomerulosclerosis (FSGS) mice for eight consecutive weeks led to an increase in serum creatinine and proteinuria and aggravation of renal interstitial fibrosis. Similarly, 8 weeks of high-dose dexamethasone administration exacerbated renal interstitial injury and interstitial fibrosis in doxorubicin-induced mice, manifested as an increase in serum creatinine and proteinuria, collagen deposition and α-SMA expression. On this basis, we found that dexamethasone could enhance MDSC expression and secretion of the fibrosis-related cytokines TGF-ß and IL-10. Mechanistically, we revealed that dexamethasone promotes the expression of immunoglobulin-like transcription factor 4 (ILT4), which enhances the T-cell inhibitory function of MDSCs and promotes the activation of STAT6, thereby strengthening the expression and secretion of TGF-ß and IL-10. Knocking down ILT4 alleviated renal fibrosis caused by adoptive transfer of MDSCs. Therefore, our findings demonstrate that the role and mechanism of dexamethasone mediate the expression and secretion of TGF-ß and IL-10 in MDSCs by promoting the expression of ILT4, thereby leading to renal fibrosis.

Homoharringtonine combined with cytarabine to treat chronic myelogenous leukemia in myeloid blast crisis and its impact on bone marrow CD34+CD7+ cells.

BACKGROUND: The therapeutic response of chronic myelogenous leukemia in myeloid blast crisis (CML-MBC) is very poor. AIM: To explore the therapeutic effect of homoharringtonine (HHT) combined with cytarabine (HA regimen) on CML-MBC and its influence on bone marrow CD34+CD7+ cells. RESULTS: Thirty-four patients with CML-MBC were treated with the HA regimen and bone marrow CD34+CD7+ cells were assayed prior to and after treatment. Among 33 evaluable patients, the overall hematological response (complete/ partial hematological response and hematological improvement) was 60.1%. Seven patients (21.2%) had a cytogenetic response 12 months after treatment. In the untreated CMLMBC patients, the proportion of bone marrow CD34+CD7+ cells was much higher than in the control group (19.4 ± 7.9 vs. 4.4 ± 1.5%, p < 0.05) and decreased to 14.1 ± 7.1% (p < 0.05) after treatment. Before treatment, the proportion of CD34+CD7+ cells was lower in the patients who had a hematological response to the HA regimen than in the patients who did not respond. CONCLUSION: The HA regimen is an effective treatment for CML-MBC and CD34+CD7+ cells may be one of the valuable clinical parameters to assess treatment effectiveness.

[Transcriptome Analysis of Chronic Myelogenous Leukemia Cell Line with Imatinib Resistance].

OBJECTIVE: To investigate the regulation of chronic myelogenous leukemia （CML） imatinib resistant genes, in order to improve the therapeutic effect of CML imatinib resistant patients. METHODS: The human CML cell line K562 and imatinib-resistant K562 cells (K562/G01) were collected, and transcriptome of the cells were achieved by RNA-seq. The sequencing data were analyzed by using standard procedures. RESULTS: Compared with K562 cells, 464 genes were significantly changed in K562/G01 cells, including 163 up-regulated and 301 down-regulated genes. The GO function annotation analysis and KEGG pathway analysis results showed that the differentially expressed genes were mainly involved in biological processes such as oxidative phosphorylation, localization to protein organelle, ribonucleoprotein complex biogenesis and so on. Gene Set Enrichment Analysis (GSEA) plots showed that 5 gene-sets were up-regulated in K562/G01 significantly, including the pathway of TGF-beta, mTOR and CML. CONCLUSION: CML imatinib resistance is associated with oxidative phosphorylation, during which the pathway of TGF-beta and mTOR are significantly up-regulated.

KDM6A promotes imatinib resistance through YY1-mediated transcriptional upregulation of TRKA independently of its demethylase activity in chronic myelogenous leukemia.

Rationale: Despite landmark therapy of chronic myelogenous leukemia (CML) with tyrosine kinase inhibitors (TKIs), drug resistance remains problematic. Cancer pathogenesis involves epigenetic dysregulation and in particular, histone lysine demethylases (KDMs) have been implicated in TKI resistance. We sought to identify KDMs with altered expression in CML and define their contribution to imatinib resistance. Methods: Bioinformatics screening compared KDM expression in CML versus normal bone marrow with shRNA knockdown and flow cytometry used to measure effects on imatinib-induced apoptosis in K562 cells. Transcriptomic analyses were performed against KDM6A CRISPR knockout/shRNA knockdown K562 cells along with gene rescue experiments using wildtype and mutant demethylase-dead KDM6A constructs. Co-immunoprecipitation, luciferase reporter and ChIP were employed to elucidate mechanisms of KDM6A-dependent resistance. Results: Amongst five KDMs upregulated in CML, only KDM6A depletion sensitized CML cells to imatinib-induced apoptosis. Re-introduction of demethylase-dead KDM6A as well as wild-type KDM6A restored imatinib resistance. RNA-seq identified NTRK1 gene downregulation after depletion of KDM6A. Moreover, NTRK1 expression positively correlated with KDM6A in a subset of clinical CML samples and KDM6A knockdown in fresh CML isolates decreased NTRK1 encoded protein (TRKA) expression. Mechanistically, KDM6A was recruited to the NTRK1 promoter by the transcription factor YY1 with subsequent TRKA upregulation activating down-stream survival pathways to invoke imatinib resistance. Conclusion: Contrary to its reported role as a tumor suppressor and independent of its demethylase function, KDM6A promotes imatinib-resistance in CML cells. The identification of the KDM6A/YY1/TRKA axis as a novel imatinib-resistance mechanism represents an unexplored avenue to overcome TKI resistance in CML.

Acute Myeloid Leukemia with NUP98-RARG Gene Fusion Similar to Acute Promyelocytic Leukemia: Case Report and Literature Review.

Retinoic acid receptor gamma (RARG) belongs to the nuclear receptor superfamily and has 90% homology to RAR alpha (RARA) and RAR beta. The promyelocytic leukemia (PML)-RARA fusion gene has been implicated in acute promyelocytic leukemia (APL). RARG gene rearrangement has been identified in a rare subtype of acute myeloid leukemia (AML) that resembles APL. To date, only 10 cases of gene rearrangements involving RARG (nucleoporin [NUP]98-RARG, promyelocytic leukemia protein-RARG, cleavage and polyadenylation-specific factor 6-RARG, or nucleophosmin [NPM]1-RARG-NPM1) have been reported. These patients show characteristics similar to APL, including bone marrow morphology, coagulation abnormality, and immunophenotype; however, they are resistant to all-trans retinoic acid and arsenic trioxide treatment. Moreover, there is no optimal therapeutic regimen for this subtype of AML. In this study, we report the clinical presentation and experimental findings of a case of AML with NUP98-RARG gene fusion similar to APL and review other cases of RARG gene rearrangement described in the literature.

[Allicin enhances cytotoxicity of CPT-11 to colon cancer LoVo cell in vitro].

OBJECTIVE: To study the effect of allicin on human colon cancer cell line LoVo and the combined effect of allicin and CPT-11 on this cancer cell line. METHOD: The LoVo cells were cultured in vitro and treated with allicin in different concentrations. MTT assay was used to test dynamically the cell growth inhibiting effect. Apoptosis induction (Annexin-V-FITC/PI) and modulation of DNA cell cycle were measured by flow cytometry. The change of cytotoxicity of CPT-11 after combination of allicin at the concentration of 4.0, 8.0 mg x L(-1) were investigated. RESULT: Allicin had inhibitive effect on growth of LoVo cells in a dose and time dependent manner, with IC50 value of 32.23, 10.74, 6.58 mg x L(-1) at 24 h, 48 h and 72 h, respectively. The apoptosis rate of LoVo cells increased progressively as the cells were treated with increasing concentration of allicin in 24 h, while the apoptosis rate achieved peak value when the cells were treated with allicin at the concentration of 8 mg x L(-1) in 48 h. The result indicated the low concentrations of allicin (< 4 mg x L(-1)) lead to G2/M cell cycle arrest, and higer concentrations ( > 4 mg x L(-1)) exert G1 + G2/M cell cycle arrest in 24 h. Compared with single use of CPT-11, the combined use of CPT-11 and allicin (4.0, 8.0 mg x L(-1), respectively) showed increasing cytotoxicity on the LoVo cells, with IC50 of 24 h decreasing from 47.5 to 7.4 and 7.2 mg x L(-1), respectively. CONCLUSION: Allicin has significant anti-proliferation effect on human colon cancer cell line LoVo by induction of apoptosis and arrestment of cell cycle and can enhance the cytotoxicity of CPT-11 on the colon cancer LoVo cell.

Dexmedetomidine reduces oxidative stress and provides neuroprotection in a model of traumatic brain injury via the PGC-1α signaling pathway.

The protective effects of dexmedetomidine (DEX) mediated by reductions of oxidative stress, mitochondrial damage and disintegration have been demonstrated in many injury models. However, whether DEX has a beneficial effect on traumatic brain injury (TBI) remains unknown. In this study, the neuroprotective effect of DEX and its potential mechanism were assessed in a model of TBI. DEX treatment relieved encephala edema and neuron cell apoptosis and increased behavioral function. These protective effects were accompanied by upregulation of peroxisome proliferator-activated receptor gamma coactivator-1 (PGC-1α) expression. These findings imply that DEX protects neurons following TBI, possibly by activating the PGC-1α pathway. The data will help clarify the mechanisms responsible for the anti-apoptosis effect of DEX with possible involvement of the PGC-1α pathway.

[Mechanism of mTOR Pathway in K562 cell Apoptosis Induced by Homoharringtonine].

OBJECTIVE: To investigate the effect of homoharringtonine (HHT) on proliferation and apoptosis of CML cell line K562 cells and to explore its possible mechanism through mTOR pathway. METHODS: K562 cells were cultured with different concentrations of HHT or in its combination with mTOR inhibitor rapamycin (RAPA) for 24 hours. The cell viability was analyzed by CCK-8 assay, the cell apoptosis was detected by flow cytometry, the expressions of BCL-6, Caspase-3 and mTOR signal pathway related proteins was assayed by Western blot, the expression of BCL-6 mRNA was determined by RT-PCR. RESULTS: The HHT inhibited proliferation and induced apoptosis of K562 cells in a concentration-dependent manner(r=0.970). With the increasing of HHT concentration, the expression level mTOR signal pathway related proteins increased(r=0.908), while the mRNA and protein expression levels of BCL-6 decreased(rmRNA=-0.961, rprotein =-0.981), as compared with the HHT alone, the combination of HHT with RAPA could down-regulate the expression of mTOR signal pathway related protein and caspase-3, and up-regulated expression of BCL-6. CONCLUSION: HHT induces apoptosis of K562 cells by inhibiting BCL-6 expression through mTOR signal pathway.

[Effect of Homoharringtonine Combined with Imatinib on the K562/G01 Cells and Its Mechanism].

OBJECTIVE: To explore the effect of homoharringtonine(HHT) combined with imatinib(IM) on proliferation and apoptosis of K562/G01 cells and its potential mechanism. METHODS: K562/G01 cells were cultured with HHT and/or IM. CCK-8 assay was used to detect cell proliferation. Cell apoptosis and phosphorylated tyrosine levels were analyzed by flow cytometry. The expression levels of p210, PI3K, p-Akt and Akt protein were determined by Western blot. RESULTS: Compared with HHT or IM alone, drug combination significantly inhibited cell proliferation and induced apoptosis of K562/G01 cells (both P< 0.05). HHT combined with IM could inhibit the levels of phosphorylated tyrosine and phosphorylated Crkl and downregulate the expressions of p210, PI3K and p-Akt in K562/G01 cells. CONCLUSION: HHT combined with IM can synergistically inhibit proliferation and induce apoptosis of K562/G01 cells by suppressing the p210 expression and its kinase activity.

[Effects of PCI-32765 and Dasatinib on the Acute Lymphoblastic Leukemic Cells and Their Mechanisms].

OBJECTIVE: To investigate the effects of Btk inhibitor (PCI-32765) and BCR-ABL tyrosine kinase inhibitor (Dasatinib) on proliferation and apoptosis of acute lymphoblastic leukemia (ALL) cell lines (Sup-B15, RS4;11) and the possible mechanism. METHODS: RS4;11 and Sup-B15 cells were treated with PCI-32765 and Dasatinib, the cell proliferation and apoptosis were detected by CCK-8, the Btk and other apoptotic proteins were detected by Western blot. RESULTS: PCI-32765 could inhibit the proliferation of RS4;11 and Sup-B15 cells in a dose-dependent manner, Sup-B15 cells were more sensitive to PCI-32765 than RS4;11 cells, their IC50 were 3 µmol/L and 8 µmol/L respectively, the difference between them was statistically significant (P<0.05). Dasatinib also could inhibit the proliferation of RS4;11 cells and Sup-B15 cells in a dose-dependent manner. The IC50 was 5 µmol/L and 5 nmol/L, respectively, the difference between them was statistically very significant (P<0.01), and the inhibitory effect was enhanced by the combination of Damatinib with the PCI-32765(P<0.05). The cell survival rate decreased gradually in PCI-32765 or Dasatinib alone group and the combination group at the different time-point (8, 12, 24, 36, 48 and 72 h), the 2 drugs showed a synergistic effect on cells in a time-dependent manner. After being treated with PCI-32765 and Dasatinib, the RS4;11 and Sup-B15 cells showed that cell shrinkage, increase of cytoplasmic density, nuclear pyknosis, deviation and karyorrhexis, and increase of the apoptotic cells in the combination group, while the promotive effect of low dosage dasatinib on apoptosis of RS4;11 cells was not strong. PCI-32765 and Dasatinib could decrease the expression and activity of BCR-ABL, Btk, Lyn, Src in Sup-B15 and RS4;11 cells. CONCLUSION: PCI-32765 or Dasatinib can inhibit the proliferation and induce the apoptosis of Sup-B15 and RS4;11 cells, PCI-32765 and Dasatinib displayed the synergistic effects. The possible mechanism may be related with the blocking of B cell receptor(BCR) signal pathway, thereby inhibiting the cell proliferation and promoting the cell apoptosis.

[Acadesine Inhibits the Proliferation of K562 Cells and Enhances their Sensitivity to Imatinib].

OBJECTIVE: To investigate the effects of AMPK agonist Acadesine (AICAR) on growth inhibition of K562 cells and their sensitivity to imatinib (IM). METHODS: K562 cells were cultured with different concentrations of AICAR alone or its combination with IM for 48 hours, the CCK-8 assay was used to detect cell proliferation, the cell cycle distribution and apoptosis were analyzed by flow cytometry. The expression levels of Cyclin D1, Cyclin E1 and Caspase 3 protein were determined by Western blot. RESULTS: AICAR inhibited the proliferation of K562 cells in dose-dependent manner, and their IC50 value was 0.45 mmol/L at 48 hours. AICAR could induce arrest of K562 cells in G1 phase and down-regulated the protein expression levels of Cyclin D1 and Cyclin E1; whereas it didn't influence the cell apoptosis. Additionally, the growth inhibition of cells induced by IM was enhanced by AICAR. CONCLUSION: AICAR can inhibit the proliferation of K562 cells by arresting the cell cycle and enhancing the sensitivity of K562 cells to IM.

ZFX Facilitates Cell Proliferation and Imatinib Resistance in Chronic Myeloid Leukemia Cells.

Zinc finger protein, X-linked (ZFX) mediates the development and progression of human cancers. However, its potential role in chronic myeloid leukemia (CML) is still unknown. The ZFX expression was significantly increased in CML patients and cell lines. Based on loss-of-function experiments in CML cells, we found that knockdown of ZFX expression impaired cell proliferation and induced mitotic arrest in G0/G1 stage and apoptosis. In addition, ZFX silencing sensitized CML cells to imatinib treatment. Further, phospho-Akt (p-Akt), CyclinD1, CyclinE1, and Bcl-2 were downregulated, and Caspase-3 was upregulated in ZFX-silenced cells. In summary, our data suggest that ZFX is a novel oncogene promoting cell proliferation and inducing imatinib resistance via PI3K/Akt signaling pathway. ZFX may represent a potential therapeutic target in CML.

Immunological status of chronic myelogenous leukemia patients with complete cytogenetic response after treatment.

BACKGROUND: The aim of this study was to compare the T lymphocyte subsets of chronic myelogenous leukemia (CML) patients who had a complete cytogenetic response (CCyR) after treatment with imatinib (IM) or homoharringtonine (HHT). METHODS: T and Th lymphocyte subsets in CCyR patients treated with HHT (n = 15) or IM (n = 16) were assayed with flow cytometry. RESULTS: It was found that there were no differences in T lymphocyte subset proportions at the time of achieving CCyR0 and also no difference in the CD8+T cell proportions at the 12th month after CCyR (CCyR12), between the 2 groups. The values of CD3+T, CD4+T, CD8+T, CD4+T/CD8+T, Th1 and Th2 cells were 54.21% ± 6.12% vs. 44.32% ± 4.85%, 29.83% ± 5.53% vs. 22.27% ± 3.22%, 24.66 ± 4.91 vs. 25.41% ± 5.72% , 1.11 ± 0.23 vs. 0.92 ± 0.19, 10.23% ± 4.24% vs. 8.34% ± 3.45% and 11.12% ± 3.91% vs. 13.67% ± 4.78%, respectively in the HHT group and IM group at CCyR12, which meant that the proportions of CD3+T, CD4+T and Th1 cells and the ratio of CD4+T to CD8+T cells were higher and the CD8+T and Th2 cell proportions were lower in the HHT group than in the IM group. CONCLUSIONS: HHT has a weaker immunodepression effect on T lymphocyte subsets compared with IM.

[Effect of YM155 on Apoptosis and Autophagy of K562 Cells].

OBJECTIVE: This study was purposed to investigate the effect of YM155, a survivin inhibitor, on the apoptosis and autophagy of K562 cells. METHODS: K562 cells were treated with YM155 at different concentration. Cell survival was analyzed by CCK-8 assay, the cell apoptosis was detected by flow cytometry. Survivin, BCL-2 and beclin1 mRNA expressions were determined by RT-PCR. Survivin, BCL-2, caspase-3, PARP and LC-3 protein expressions were assayed by Western blot. RESULTS: YM155 inhibited the proliferation of K562 cells in a time- and dose-dependent manners. With the increasing of YM155 concentration and prolonging of action time, the expression levels of mRNA and protein of survivin and BCL-2 decreased, while the expression levels of caspase-3, PARP, beclin1 and LC-3 increased. Compared with the YM155 group, the protein levels of LC-3 and caspase-3 were lower in YM155 combined with 3-MA group. CONCLUSION: YM155 can inhibit K562 cell proliferation by inducing apoptosis and autophagy, while autophagy induction effect can enhance its cytotoxic effect.

[Time rhythm of homoharringtonine inducing K562 cell apoptosis and its mechanism].

This study was aimed to explore the change of K562 cell apoptosis at different time point after homoharringtonine (HHT) treatment and its mechanism. After treatment of K562 cells with 10 ng/ml HHT, the cell viability was tested with MTT assay; the expression of caspase-3 was detected with Western blot; the BCL-2 expression was analyzed with flow cytometry; the autophagosome was observed by electron microscopy. The results showed that the viability of K562 cells reduced gradually from day 1 to day 5 and ascended from day 6 to day 8 after HHT treatment. At the same time, the cleaved caspase-3 expression level of K562 cells increased gradually from day 1 to day 7, but reduced at the day 8 (P < 0.05). From day 1 to day 8 after HHT treatment, the BCL-2 expression level declined firstly and then went up (P < 0.05). Autophagosome was also seen remarkably at day 8 after HHT treatment. It is concluded that the apoptosis level of K562 cells after being treated with HHT enhances firstly and then declines , which may be associated with higher autophagy level in the late stage of HHT treatment.

[Effect of PCI-32765 and bortezomib on proliferation and apoptosis of B-cell tumor cell lines and its mechanisms].

This study was aimed to investigate the effect of Btk inhibitor PCI-32765 and the proteasome inhibitor bortezomib on Raji and Ramos cell proliferation, apoptosis, and its mechanisms. Raji and Ramos cells were treated with PCI-32765 and bortezomib alone and/or their combination. The cell proliferation and apoptosis were detected by CCK-8 and flow cytometry respectively, the expression level of Btk, NFκB, c-IAP1, Bcl-xL and caspase-3 protein were measured by Western blot. The results indicated that: (1) after Raji and Ramos cells were treated with PCI-32765 (0.5, 1.0, 2.0, 3.0, 4.0, 5.0, 6.0 µmol/L) alone and bortezomib (10, 20, 30, 40, 50, 60, 80 nmol/L) alone and their combination for 48 h, the cell proliferation and vitality were inhibited in a dose-dependent manner and both had synergistic effect; (2) Raji and Ramos cells were treated with PCI-32765 (2.0 µmol/L) and bortezomib (20 nmol/L) alone and their combination for 8, 12, 24, 36, 48 and 72 h, the cell proliferation and vitality were inhibited in a time-dependent manner, the two drugs displayed a synergistic effects; (3) the Raji and Ramos cells were treated with PCI-32765 (2.0 µmol/L) and bortezomib (20 nmol/L) alone and their combination for 48 h, all these treatments could induce significant apoptosis of Raji and Ramos cells.In Raji cell experiment, the cell apoptosis rate in the control group, PCI-32765 group, bortezomib group and PCI-32765 and bortezomib combination group were 10.34 ± 0.53%, 24.26 ± 0.91%, 43.66 ± 1.08% and 74.06 ± 0.72% respectively, and the differences was statistically significant among the different groups (P < 0.05). In Ramos cell experiment, the cell apoptosis rate in the control group, PCI-32765 group, bortezomib group and PCI-32765 and bortezomib combination group are 15.16 ± 1.49%, 71.36 ± 0.82%, 75.32 ± 2.36% and 84.30 ± 0.91% respectively, the differences was statistically significant among the different groups (P < 0.05); (4) PCI-32765 and bortezomib could inhibit the expression level of intracellular Btk, NFκB, Bcl-xl and c-IAP1 proteins, but up-regulate the expression level of caspase-3. It is concluded that PCI-32765 and bortezomib can synergistically inhibit the proliferation and induce apoptosis of Raji and Ramos cells, the mechanism may be associated with inhibition of Btk and NFκB activity, down-regulation of anti-apoptotic proteins expression, such as Bcl-xl and c-IAP1, and increase of caspase-3 expression.

[Expression of Btk and NFκB in acute myeloid leukemia cells and its significance].

This study was purposed to investigate the expression of Btk and NFκB in acute myeloid leukemia (AML) cells and its significance. Bone marrow mononuclear cell specimens were taken from 14 AML patients who were in new diagnosis and complete remission respectively, the expressions of Btk and NFκB at mRNA and protein levels were detected by RT-PCR and Western blot, respectively. The results showed that Btk and NFκB expressed in all the samples at RNA and protein levels. At protein level, Btk and NFκB expressions were higher in the cells from newly diagnosed AML patients than that in the cells from patients in complete remission stage (P < 0.05). It is concluded that Btk and NFκB may play an important role in the development and progression of AML, they may be used as potential therapeutic targets of AML and used in predicting the prognosis.

[Effect of homoharringtonine on expression of NF-κB and BCL-2 proteins in K562 cells].

This study was aimed to investigate the effect of homoharringtonine (HHT) on K562 cell proliferation, apoptosis and expression of BCL-2 and NF-κB proteins. The cells proliferation was assayed with MTT method, the cell apoptosis, cell cycle and BCL-2 expression were analyzed with flow cytometry, NF-κB protein expression was detected with Western blot. The results showed that HHT concentration-dependently inhibited proliferation of K562 cells, the IC50 at 48 h was 43.89 ng/ml. Treated with HHT 10 ng/ml for 48 h, K562 cell apoptosis significantly increased, cell cycle was blocked at G0/G1, the expression level of BCL-2 and NF-κB proteins was lower than that in control group (P < 0.05). It is concluded that HHT may inhibit the proliferation of K562 cells, and down-regulating expression levels of BCL-2 and NF-κB may be one of its anti-CML mechanisms.

Effect of homoharringtonine on bone marrow CD34 + CD117 + cells in patients with chronic myelogenous leukemia.

This study investigated the effect of homoharringtonine (HHT) on bone marrow CD34 + CD117 + cells in patients with chronic myelogenous leukemia (CML). Fifty-seven patients with CML who could not receive either imatinib or interferon-α were treated with HHT (n = 31) or hydroxycarbamide (HU) (n = 26) to induce and maintain remission, and bone marrow CD34 + CD117 + cells were assayed with flow cytometry. The proportion of CD34 + CD117 + cells was higher in untreated patients (24.7 ± 6.4%) than in donors (4.4 ± 1.1%) and decreased remarkably in patients who had hematological remission (11.2 ± 3.1%) and cytogenetic response (8.9 ± 3.1%) as compared with those without (27.8 ± 7.3% and 18.5 ± 5.3%, respectively) at 12 months after therapy. The hematological remission rate for patients with proportion of CD34 + CD117 + cells ≥ 20% prior to treatment was lower (41.7%) than in patients with CD34 + CD117 + cells < 20% (78.9%; p < 0.05). However, there was no such difference of CD34 + CD117 + cell percentage in the HU group. It can be concluded that high expression of CD117 on CD34 + cells is a marker of poor prognosis and is also a target for the anti-CML effect of HHT.

[Effects of interferon-α combined with homoharringtonine on K562 cell proliferation and ß-catenin expression].

The study was aimed to investigate the synergistically effect of interferon-α (IFN-α) and homoharringtonine (HHT) on the proliferation, apoptosis, cell cycle of K562 cells and the expression of ß-catenin. The proliferation, apoptosis, cell cycle and ß-catenin mRNA expression of K562 cells treated with IFN-α and/or HHT were assayed with MTT, flow cytometry or RT-PCR respectively. The results showed that HHT alone, but not IFN-α alone, displayed a proliferation inhibition, apoptosis induction, G(0)/G(1) phase block and down-regulation of ß-catenin expression in K562 cells with concentration- and time-dependent manners. The expression level of ß-catenin mRNA after being treated with HHT was 0.5576 ± 0.0373, which were lower than that in control group (0.9369 ± 0.0142). The down-regulation of ß-catenin expression in group of IFN-α combined with HHT was higher significantly than that in HHT group (0.3737 ± 0.0529 vs 0.5576 ± 0.0373, P < 0.05). Otherwise, HHT combined with IFN-α did not demonstrate obvious toxicologic effect on bone marrow mononuclear cells. It is concluded that IFN-α combined with HHT can enhance the cytotoxic effect of HHT on K562 cells, which may be associated with down-regulation of ß-catenin expression.