Matrix metalloproteinase inhibitor reduces apoptosis induction of bone marrow cells in MDS-RA

BACKGROUND AND OBJECTIVES: We examined the involvement of apoptosis with myelodysplastic syndrome (MDS) accompanied by peripheral cytopenias despite normo-hypercellular bone marrow. MATERIALS AND METHODS: Bone marrow smears from 31 patients with MDS-refractory anemia (RA) and five normal controls were stained using the in situ end labeling (ISEL) method. Next, the inhibitory effects of a caspase-3 inhibitor, matrix metalloproteinase inhibitor (MMPI), anti-tumor necrosis factor (TNF)-alpha or anti-Fas antibody upon the apoptosis induction in overnight cultures of bone marrow cells from the patients were examined. Further, TNF-alpha, transforming growth factor (TGF)-beta and soluble Fas ligand (sFasL) concentrations in culture supernatants of the cells were assessed by enzyme-linked immunosorbent assay (ELISA). RESULTS: The incidence of ISEL-positive cells among MDS patients was significantly higher than in normal controls (50.8 +/- 14.0% vs. 11.3 +/- 2.4%; P < 0.0001). A caspase-3 inhibitor reduced significantly the ISEL-positive rates (32.6 +/- 15.2% vs. 50.2 +/- 16.5%; P < 0.0001). Anti-TNF-alpha or anti-Fas antibody reduced the ISEL-positive rates significantly (28.2 +/- 6.0%, 29.2 +/- 5.8%, vs. 44.2 +/- 3.4%, P < 0.001, P = 0.001, respectively). KB-R7785 also significantly decreased the ISEL-positive rates (18.0 +/- 9.3% vs. 43.6 +/- 14.0%; P < 0.0001). The concentration of TNF-alpha was significantly reduced by KB-R7785 (P < 0.05), whereas that of TGF-beta was not. Concentration of sFasL was under detectable level in the present assay system. The derivatives of KB-R7785 that can be administrated orally showed inhibitory effect on apoptosis induction as well. CONCLUSIONS: These findings suggest that MMPIs inhibits the apoptosis induction of MDS bone marrow cells via the inhibition of TNF-alpha and probably sFasL secretion, and that MMPIs can be used to control the abnormal induction of apoptosis in MDS.     

N-ras mutations are associated with poor prognosis and increased risk of leukemia in myelodysplastic syndrome

To evaluate the clinical significance of N-ras mutations in the myelodysplastic syndrome (MDS) archival bone marrow samples from 252 patients were studied for the presence of N-ras exon I mutations using polymerase chain reaction amplification and differential oligonucleotide hybridization. Subsequently, clinical information about these patients was obtained and analyzed. Of 220 evaluable patients, 20 (9%) had point mutation of N-ras involving codon 12. Individuals with N- ras mutation had a significantly shorter survival period than those who were N-ras negative (P = .02). An increased risk of acute myelogenous leukemia (AML) was also found in patients with N-ras mutations (P = .005). N-ras mutations were not associated with any French-American- British (FAB) subtype, with the presence of increased myeloblasts, or with chromosomal aberrations in the bone marrow. However, the presence of increased bone marrow blasts was strongly associated with poor survival rate and risk of AML (P < .001 for each). After stratifying for the percentage of blasts, N-ras mutations remained significantly associated with shorter survival period (P = .04) and increased risk of AML (P = .02). Bone marrow cytogenetic abnormalities, particularly when multiple abnormalities were present, were significantly associated with a poor prognosis (P < .001). In conclusion, N-ras mutation, although relatively infrequent in MDS, is associated with short survival period and increased probability of developing AML.     

Evidence for expression of early myeloid antigens in mature,non-blast myeloid cells in myelodysplasia

Myelodysplastic syndromes (MDS) are clonal hematopoietic stem cell disorders with frequent cytogenetic abnormalities. They can arise de novo or be related to therapy. Although blasts in MDS have been studied extensively, there is little information available on the mature, non-blast myeloid cells (NBMCs). We used a retrospective case-control study design. NBMC populations in MDS (48 cases) and in tumor-free control (12 cases) bone marrow samples were analyzed using multiparameter flow cytometry for mean side scatter (SSC) channel number and for expression of aberrant cell surface antigens. MDS cases were stratified on the basis of cytogenetic abnormalities. We report that NBMCs in MDS with normal karyotype expressed significantly higher HLA-DR than controls (P = 0.034). NBMCs in MDS cases with cytogenetic abnormalities and with > or =5% marrow blasts, compared with controls, had significantly higher CD34 and higher HLA-DR but lower CD10 and lower SSC mean channel number. CD34 expression in NBMCs was significantly greater in therapy-related MDS compared with de novo MDS ( P = 0.01), although the presence of cytogenetic abnormalities was not different ( P > 0.05). These data suggest that bone marrow, mature, NBMCs have phenotypic changes in MDS that are not seen in normal controls.     

Survivin expression, apoptosis and proliferation in chronic myelomonocytic leukemia

We analyzed the expression of the inhibitor of apoptosis survivin by immunocytochemistry in bone marrow cells from patients with chronic myelomonocytic leukemia (CMML) to evaluate possible abnormalities in comparison with other myelodysplastic (MDS) and myeloproliferative syndromes, and to investigate a possible correlation between survivin expression and altered apoptosis or proliferation, or relevant laboratory and clinical findings. Thirty-four patients with CMML [18 MDS-CMML and 16 myeloproliferative disorder (MPD)-CMML], 90 with MDS, 41 with acute myeloid leukemia (AML), 19 with chronic MPD and 25 control subjects were studied. In normal samples survivin was never detectable. In CMML survivin levels higher than in MDS and AML (P < 0.0001), but similar to those found in MPD were observed. In CMML and MDS apoptosis was significantly higher compared to normal controls and all other subtypes of leukemias (P < 0.0001). Proliferation did not differ significantly in normal controls, MDS and CMML; the lowest levels were observed in AML and MPD (P < 0.0001). In CMML there was no correlation between survivin expression and blast cell percentage, apoptosis or proliferation, FAB or WHO subgroup. Proliferation was higher in MDS-CMML and tended to correlate with overall survival. CMML-2 cases with higher survivin expression showed higher evolution rate and shorter survival. In conclusion, CMML is characterized by high proliferation and apoptosis. Survivin overexpression, by disrupting the balance between cell proliferation/differentiation and apoptosis, may play an important role in its pathophysiology. The detection of survivin-deregulated expression may provide a useful tool for diagnosis, prognosis and a possible target for experimental treatments.     

Mutations of the human telomerase RNA gene (TERC) in aplastic anemia and myelodysplastic syndrome

Mutations in the human telomerase RNA (TERC) occur in autosomal dominant dyskeratosis congenita (DKC). Because of the possibility that TERC mutations might underlie seemingly acquired forms of bone marrow failure, we examined blood samples from a large number of patients with aplastic anemia (AA), paroxysmal nocturnal hemoglobinuria (PNH), and myelodysplasia (MDS). Only 3 of 210 cases showed heterozygous TERC mutations: both nucleotide 305 (n305) (G>A) and n322 (G>A) were within the conserved region (CR) 4-CR5 domain; n450 (G>A) was localized to the boxH/ACA domain. However, only one patient (with a mutation at n305 [G>A]) had clinical characteristics suggesting DKC; her blood cells contained short telomeres and her sister also suffered from bone marrow failure. Another 21 patients with short telomeres did not show TERC mutations. Our results suggest that cryptic DKC, at least secondary to mutations in the TERC gene, is an improbable diagnosis in patients with otherwise typical AA, PNH, and MDS.     

Frequency and prognostic impact of mutations in SRSF2, U2AF1, and ZRSR2 in patients with myelodysplastic syndromes

Mutations in genes of the splicing machinery have been described recently in myelodysplastic syndromes (MDS). In the present study, we examined a cohort of 193 MDS patients for mutations in SRSF2, U2AF1 (synonym U2AF35), ZRSR2, and, as described previously, SF3B1, in the context of other molecular markers, including mutations in ASXL1, RUNX1, NRAS, TP53, IDH1, IDH2, NPM1, and DNMT3A. Mutations in SRSF2, U2AF1, ZRSR2, and SF3B1 were found in 24 (12.4%), 14 (7.3%), 6 (3.1%), and 28 (14.5%) patients, respectively, corresponding to a total of 67 of 193 MDS patients (34.7%). SRSF2 mutations were associated with RUNX1 (P < .001) and IDH1 (P = .013) mutations, whereas U2AF1 mutations were associated with ASXL1 (P = .005) and DNMT3A (P = .004) mutations. In univariate analysis, mutated SRSF2 predicted shorter overall survival and more frequent acute myeloid leukemia progression compared with wild-type SRSF2, whereas mutated U2AF1, ZRSR2, and SF3B1 had no impact on patient outcome. In multivariate analysis, SRSF2 remained an independent poor risk marker for overall survival (hazard ratio = 2.3; 95% confidence interval, 1.28-4.13; P = .017) and acute myeloid leukemia progression (hazard ratio = 2.83; 95% confidence interval, 1.31-6.12; P = .008). These results show a negative prognostic impact of SRSF2 mutations in MDS. SRSF2 mutations may become useful for clinical risk stratification and treatment decisions in the future.     

Allele and haplotype frequency at human leucocyte antigen class I/II and immunomodulatory cytokine loci in patients with myelodysplasia and acute myeloid leukaemia: in search of an autoimmune aetiology

An autoimmune mechanism in the pathogenesis of myelodysplastic syndrome (MDS) is suggested by response to immunosuppression, with CD8+ T-lymphocytes implicated in the haematopoietic suppression. We therefore sought evidence for human leucocyte antigen (HLA) restriction and variant frequency differences in selected polymorphisms at the loci for the immunomodulatory cytokines, tumour necrosis factor alpha (TNF-alpha), lymphotoxin-alpha (LT-alpha) and interleukin 10 (IL-10) in patients with MDS and acute myeloid leukaemia (AML) compared with normal controls. DNA from 150 MDS/AML patients [24 AML, 53 refractory anaemia (RA), 25 RA with excess blasts (RAEB), four RAEB in transformation (RAEBt), 21 sideroblastic leukaemia, 22 chronic myelomonocytic leukaemia] was screened. Control data was from Scottish blood donors (HLA class I/II), healthy General Practitioner-based subjects (TNF-alpha/LT-alpha) and published values (IL-10). HLA class I/II haplotypes were determined using sequence-specific primers. Polymorphisms were assayed at TNF-alpha -308, LT-alpha +252 and IL10 -824, -597 and -1082 loci. Variant frequencies of common haplotypes at HLA class I and II, high-/low-producer TNF-alpha/LT-alpha and IL-10 loci were not different between patients and controls or within the French-American-British, International Prognostic Scoring System or cytogenetic subgroups and were not associated with altered survival for MDS/AML patients. TNF2 allele frequency was greater in the MDS/AML cohort (chi2 = 6.593, P < 0.05) but the biological significance was uncertain in the absence of an increased high-producer TNF-alpha/LT-alpha haplotype frequency. We can find no genetic influence for these polymorphisms in HLA class I/II, TNF-alpha/LT-alpha and IL-10 loci on either predisposition or disease progression in MDS/AML.     

Is apoptosis a massive process in myelodysplastic syndromes?

We looked for increased apoptosis in fresh bone marrow aspirates in 40 cases of myelodysplastic syndrome (MDS), by detection of DNA fragmentation using TdT incorporation of nucleotides on 3' ends of DNA (TUNEL technique). No DNA laddering was seen. In six cases (15%) the TUNEL technique showed a moderate increase in the percentage of apoptotic cells (2.5–5% in comparison with <2% in controls).
In seven of the 34 patients with normal findings by TUNEL analysis, apoptosis was reanalysed after short-term (18 h) bone marrow culture without inducers of apoptosis. Increased apoptosis was shown in four of the seven cases by morphological analysis and/or the TUNEL technique. Increased apoptosis predominated on erythroblasts in three of them. The percentage of apoptotic cells, however, was <40% in all samples.
Our findings suggest that increased apoptosis can be detected in one half of MDS cases after cell culture. Furthermore, the precise relationship between increased apoptosis of myeloid precursors and cytopenias will have to be more precisely explored in MDS.     

Deviation of type I and type II T cells and its negative effect on hematopoiesis in myelodysplastic syndrome

Immunemediated hematopoietic suppression has been considered as one of significant pathophysiological changes in less‐advanced myelodysplastic syndrome (MDS). To explore deviation of T cell subsets and its relationship to marrow cells apoptosis, measurement of helper‐T (Th)/cytotoxic‐T (Tc) subsets as well as the deviation situation within this two subsets (Th1/Th2 and Tc1/Tc2) in marrow was performed by flow cytometry from 39 MDS patients and 13 normal controls. Interferon (INF)‐γ and tumor necrosis factor (TNF)‐α in marrow serum was simultaneously detected by ELISA (enzyme‐linked immunosorbent assay). Furthermore, apoptosis rate of marrow cells was demonstrated by TUNEL (TdT‐mediated dUTP nick end labeling). Results showed that Th and Tc subsets were unevenly activated, both deviating to type I response, which was especially obvious in patients with RCMD (according to WHO classification) and in lower‐risk cases defined by International Prognosis Scoring System (IPSS). Level of INF‐γ/TNF‐α in MDS marrow serum was markedly elevated, and so did the apoptosis rate of marrow cells. Although type I deviation was observed both in Th and Tc subsets, just Th1 cell percentage showed positive correlation with level of INF‐γ/TNF‐α and apoptotic index of nucleated cells. In addition, cytokines level in marrow serum presented positive correlation to apoptosis. We then deduced that the increased Th1 cells in marrow may account for nucleated cells apoptosis in MDS through overproduced proapoptotic cytokines such as INF‐γ and TNF‐α. Our results suggested that type I deviation of T cell subsets may play a role in pantocytopenia in MDS and the deviation pattern may be as a direct and effective parameter to predict response of immunosuppression therapy.     

Possible involvement of RasGRP4 in leukemogenesis

It is now conceivable that leukemogenesis requires two types of mutations, class I and class II mutations. We previously established a mouse bone marrow-derived HF6, an IL-3-dependent cell line, that was immortalized by a class II mutation MLL/SEPT6 and can be fully transformed by class I mutations such as FLT3 mutants. To understand the molecular mechanism of leukemogenesis, particularly progression of myelodysplastic syndrome (MDS) to acute leukemia, we made cDNA libraries from the samples of patients and screened them by expression-cloning to detect class I mutations that render HF6 cells factor-independent. We identified RasGRP4, an activator of Ras, as a candidate for class I mutation from three of six patients (MDS/MPD = 1, MDS-RA = 1, MDS/AML = 2, CMMoL/AML = 1 and AML-M2 = 1). To investigate the potential roles of RasGRP4 in leukemogenesis, we tested its in vivo effect in a mouse bone marrow transplantation (BMT) model. C57BL/6J mice transplanted with RasGRP4-transduced primary bone marrow cells died of T cell leukemia, myeloid leukemia, or myeloid leukemia with T cell leukemia. To further examine if the combination of class I and class II mutations accelerated leukemic transformation, we performed a mouse BMT model in which both AML1 mutant (S291fsX300) and RasGRP4 were transduced into bone marrow cells. The double transduction led to early onset of T cell leukemia but not of AML in the transplanted mice when compared to transduction of RasGRP4 alone. Thus, we have identified RasGRP4 as a gene potentially involved in leukemogenesis and suggest that RasGRP4 cooperates with AML1 mutations in T cell leukemogenesis as a class I mutation. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

Enhanced growth of myelodysplastic colonies in hypoxic conditions

OBJECTIVE: To determine the response of bone marrow progenitor cells from patients with myelodysplastic syndromes (MDS) to culture in physiologic oxygen tension. METHODS: Methylcellulose progenitor assays using both unfractionated bone marrow mononuclear cells (MNCs) and purified CD34(+) progenitors were performed in atmospheric oxygen (18.6% O(2)) or one of two levels of hypoxia (1% and 3% O(2)). Assays were performed using normal donor marrow, MDS patient marrow, acute myelogenous leukemia marrow or peripheral blood blasts, chronic phase chronic myelogenous leukemia (CML) marrow MNCs, and blast crisis CML peripheral blood. RESULTS: The majority of MDS samples showed decreased colony-forming units (CFU) in 18.6% O(2) compared to normal controls, as expected. However, in either 1% or 3% O(2), 9 of 13 MDS samples demonstrated augmentation of CFUs beyond that observed in normal controls, with 6 of 13 demonstrating a greater than ninefold augmentation. This effect is cell autonomous, as it persisted after purification of CD34(+) progenitor cells. Additionally, the augmented response to physiologic oxygen tension is specific to MDS, as it was not observed in either acute or chronic myelogenous leukemia samples. CONCLUSION: These results suggest that the reported decrease in MDS CFUs reflects greater sensitivity of MDS progenitors or their progeny to the nonphysiologic oxygen tensions routinely used in vitro, rather than a true decrease in progenitor frequency. Importantly, these experiments for the first time describe an experimental system that can be used to study the growth of primary cells from patients with MDS.     

Shwachman-Diamond syndrome marrow cells show abnormally increased apoptosis mediated through the Fas pathway

Shwachman-Diamond syndrome (SDS) is an inherited bone marrow disorder with varying cytopenias and a strong predilection to myelodysplastic syndrome (MDS) and acute myeloid leukemia. Previously, it was found that the percentage of CD34(+) cells in bone marrow and the in vitro colony formation from CD34(+) cells of patients with SDS were markedly reduced. For these reasons, and because apoptosis is central in the pathogenesis of bone marrow dysfunction in MDS, this study was initiated to delineate the role of apoptosis in the pathogenesis of the marrow failure. Eleven children with SDS were studied. Compared to normal controls, patients' marrow mononuclear cells plated in clonogenic cultures showed a significantly higher tendency to undergo apoptosis. The defect in SDS was found in patients with and without MDS. Patients showed a more prominent decrease in colony formation and increased apoptosis after preincubation with activating anti-Fas antibody. Fas expression on marrow cells from patients was significantly higher than from normal controls. The difference between patients and controls for Fas expression was also significant for the following cell fraction subpopulations: CD34(-)/CD38(-), CD34(-)/CD38(+), and CD34(+). In conclusion, SDS hematopoietic progenitors are intrinsically flawed and have faulty proliferative properties and increased apoptosis. Bone marrow failure in SDS appears mediated by increased apoptosis as the central pathogenetic mechanism. This increased propensity for apoptosis is linked to increased expression of the Fas antigen and to hyperactivation of the Fas signaling pathway.     

骨髓增生异常综合征患者骨髓CD34+细胞亚群及细胞周期分析

目的 探讨骨髓增生异常综合征(MDS)患者骨髓CD34+细胞亚群及细胞周期分布异常的临床意义.方法 采用流式细胞术检测50例(17例低危、33例高危)MDS患者、8例MDS转化的急性髓系自血病(MDS-AML)及25例对照组原代骨髓CD34+CD38+、CD34+CD38-细胞亚群及G0/G1期、S期和G2/M期细胞比例.结果 高危和MDS-AML组骨髓CD34+细胞比例[(2.29±2.17)%、(18.69±17.47)%]明显高于对照组[(0.36±0.49)%,P＜0.05].低危、高危及MDS-AML组CD34+CD38+细胞相对比例[(86.09±7.79)%、(81.68±11.82)%、(82.88±2.60)%]显著低于对照组[(92.21±3.85)%,P＜0.05],而CD34+CD38-细胞比例[(13.91±7.79)%、(18.32±11.82)%、(17.13±2.60)%]显著高于对照组[(7.79±3.85)%,P＜0.05].MDS组CD34+CD38-细胞比例与国际预后积分系统(IPSS)(r=0.493,P=0.001)、WHO分型预后积分系统(WPSS)积分(r=0.586,P=0.000)均呈正相关.低危、高危及MDS-AML组骨髓单个核细胞(BMMNC)中G0/G1期细胞比例[(94.52±4.32)%,(96.07±3.88)%,(94.65±4.55)%]明显高于对照组[(88.94±7.30)%,P＜0.01],而3组S期[(4.63±3.34)%,(3.45±3.80)%,(5.12±4.55)%]和G2/M期[(0.84±1.52)%,(0.48±0.74)%,(0.22±0.34)%]细胞比例明显低于对照组[(9.06±6.50)%,(2.00±2.93)%,P值均＜0.05],3组S+G2/M期细胞比例明显高于对照组(P＜0.01).CD34+CD38-细胞比例≤12.0%的MDS患者治疗有效率高于CD34+CD38-细胞比例＞12.0%的患者,但差异无统计学意义.结论 MDS患者原代骨髓CD34+细胞亚群分化异常,BMMNC存在G1期阻滞现象,提示CD34+细胞亚群和细胞周期测定可能有助于MDS患者的辅助诊断以及疗效和预后判断.     

Phase I/II trial of the combination of midostaurin (PKC412) and 5‐azacytidine for patients with acute myeloid leukemia and myelodysplastic syndrome

We investigated the combination of midostaurin and azacitidine (AZA) in patients with acute myeloid leukemia (AML) and high risk myelodysplastic syndrome (MDS). Patients received AZA 75 mg m^?2 on days 1–7 and midostaurin 25 mg bid (in cohort 1 of phase I) or 50 mg bid (in cohort 2 of Phase I and in Phase II) orally on day 8–21 during the first cycle and continuously thereafter. Fourteen patients were enrolled in the phase I and 40 in the phase II. Overall response rate was 26%. The median remission duration (RD) was 20 weeks and was significantly longer in patients with FLT3 mutations not previously exposed to other FLT3 inhibitors (P = 0.05) and in patients not previously transplanted (P = 0.01). Thirty‐two (59%) patients have died, all of complications related to disease progression. G3‐4 nonhematological toxicity was reported in 38 (70%) patients, most frequently infections (56%), ejection fraction reduction (11%), and diarrhea or nausea/vomiting (9% each). The combination of midostaurin and AZA is an effective and safe regimen in patients with AML and high‐risk MDS. Patients with FLT3 mutations but not previously exposed to other FLT3 inhibitors and patients not previously transplanted derived the greatest benefit. Further studies with this combination are warranted. Am. J. Hematol. 90:276–281, 2015. © 2014 Wiley Periodicals, Inc.     

Analysis of mitochondrial DNA in 104 patients with myelodysplastic syndromes

OBJECTIVE: To determine the frequency and spectrum of somatic mutations of mitochondrial DNA (mtDNA) in bone marrow of patients with myelodysplastic syndrome (MDS). MATERIALS AND METHODS: Analysis included 104 patients with MDS (24 refractory anemia, 32 refractory anemia with ringed sideroblasts, 34 refractory anemia with excess of blasts, 7 refractory anemia with excess of blasts in transformation to acute leukemia, and 7 chronic myelo-monocytic leukemia), 3 patients with acute myeloid leukemia from MDS, and 36 patients with myeloproliferative disease (23 chronic myeloid leukemia, 9 polycythemia vera, 4 idiopathic myelofibrosis). Mutation scanning was performed using heteroduplex analysis with denaturing high-performance liquid chromatography (dHPLC). The entire mitochondrial genome was amplified in 67 overlapping polymerase chain reaction fragments carefully optimized regarding DNA melting profiles. Abnormal dHPLC findings were confirmed by DNA sequencing. RESULTS: Heteroplasmic mtDNA mutations, mostly transitions, were identified in 56% of MDS and 44% of myeloproliferative disorders patients. In MDS, mutation frequency increased with age and more-advanced disease. Mutational spectra showed no hot spots and were similar in different types of MDS. Heteroplasmic mutations generally did not represent known polymorphisms, and about half of them affected conserved amino acids or nucleotides. Mutations were less frequent in protein encoding genes (50 per 10(6) base pairs) than other mitochondrial genes (transfer RNAs, ribosomal RNAs, and control region; about 80 per 10(6) base pairs). CONCLUSIONS: As mitochondria often show ultrastructural abnormalities in MDS, including pathological iron accumulation, mitochondrial dysfunction may contribute to MDS pathology. We found a high frequency of acquired mtDNA mutations in MDS. However, their functional importance remains unclear, considering that genotype correlates poorly with phenotype in mitochondrial diseases. The clonally expanded mtDNA mutations in MDS support the concept of age-related damage to mtDNA in hematopoietic stem cells.     

骨髓增生异常综合征患者骨髓细胞凋亡的初步探讨

采用TUNEL法对26例骨髓增生异常综合征（MDS）、11例巨幼细胞贫血（MegA)、8例阵发性血红蛋白尿（PNH）、6例Evans综合征患者和10例正常健康志愿者的单个核细胞（BMMNC）凋亡进行探讨,结果发现,50％MDS呈现凋亡过度,MegA、PNH和Evans综合征患者与对照组无显著差异。MDS患者凋亡累及粒、红、巨三系各阶段造血细胞,随病情演变,凋亡程度渐下降,提示凋亡过度为MDS无效造血机制之一,病情演变化可能与异常克隆逃逸凋亡有关,抗凋亡疗法可试用于早期MDS。     

骨髓异常增生综合征酪氨酸激酶受体FLT3和c-KIT基因表达异常的研究

目的:本研究旨在检测骨髓异常增生综合征(MDS)患者骨髓中酪氨酸激酶受体FLT3、c-KIT基因表达水平及FLT3-LM,以讨论FLT3、c-KIT受体对于MDS患者的临床意义。方法:收集38例诊断明确的MDS患者及10例非恶性血液病患者的骨髓并提取单个核细胞,应用PCR检测FLT3基因表达水平及FLT3基因长度突变(FLT3-LM);应用逆转录聚合酶链反应(RT-PCR)检测c-KIT基因表达水平。结果:38例MDS患者骨髓单个核细胞有11例检测到FLT3基因表达,而对照组均未有FLT3基因表达,2者差异有统计学意义(P<0.05)。11例FLT3受体表达阳性患者中有2例存在FLT3-LM,阳性率为18.2%,10例对照均未发现FLT3-LM。38例MDS患者中有7例检测到c-KIT基因表达,而10例对照组均未有c-KIT基因表达,阳性率为18.4%,2者差异有统计学意义(P<0.05),且FLT3-LM、c-KIT基因表达多为高危患者。结论:以上研究显示MDS患者存在FLT3、c-KIT基因表达异常,且FLT3-LM、c-KIT(+)多发生在高危患者。提示酪氨酸激酶受体FLT3、c-KIT基因表达异常对于...     

Megakaryocyte apoptosis in immune thrombocytopenia

The mechanisms of platelet underproduction in immune thrombocytopenia (ITP) remain unknown. While the number of megakaryocytes is normal or increased in ITP bone marrow, further studies of megakaryocyte integrity are needed. Megakaryocytes are responsible for the production of platelets in the bone marrow, and they are possible targets of immune-mediated injury in ITP. Since the biological process of megakaryocyte apoptosis impacts platelet production, we investigated megakaryocyte DNA fragmentation as a marker of apoptosis from ITP bone marrow biopsies. Archived bone marrow biopsy specimens from ITP patients, bone marrow specimens from controls with normal platelet counts, and bone marrow specimens from thrombocytopenic controls with myelodysplastic syndrome (MDS) were evaluated. Sections were stained with anti-CD61 for megakaryocyte enumeration, and terminal deoxynucleotidyl transferase dUTP nick-end labeling was used as an apoptotic indicator. In ITP patients, megakaryocyte apoptosis was reduced compared to nonthrombocytopenic controls. Megakaryocyte apoptosis was similarly reduced in thrombocytopenic patients with MDS. These results suggest a link between megakaryocyte apoptosis and platelet production.     

Comparative analysis of G-CSFR and GM-CSFR expressions on CD34+ cells in patients with aplastic anemia and myelodysplastic syndrome

The aim of this article was to explore the pathogenetic differences, as well as to provide a new way for the differential diagnosis of these two diseases by comparative analysis of CD(34)(+) cells numbers and their surface expression of granulocyte colony-stimulating factor receptor (G-CSFR) and granulocyte-macrophage colony-stimulating factor receptor (GM-CSFR) in patients with aplastic anemia (AA) and myelodysplastic syndrome (MDS). Twenty-seven patients with AA, 45 patients with MDS, and 20 normal controls were enrolled in this study. The ratio of CD(34)(+) cells and their surface expression of G-CSFR and GM-CSFR were detected by flow cytometry (FCM). The ratio of CD(34)(+) cells in BMMNC of AA, MDS patients and controls were 0.2438 +/- 0.1129%, 2.1677 +/- 1.1345% and 1.0792 +/- 0.3221%, respectively. Compared with normal controls as well as MDS patients, the ratio of CD(34)(+) cells in BMMNC of AA was significantly reduced (P < 0.05). The ratio of CD(34)(+) cells in MDS was significantly elevated than controls (P < 0.05). The ratio of CD(34)(+) cells in BMMNC of MDS-RA and MDS-RAEB patients were 1.2821 +/- 0.4658% and 3.7729 +/- 2.3360%, respectively. Compared with normal controls and MDS-RA patients, the ratio of CD(34)(+) cells in MDS-RAEB was significantly elevated (P < 0.05). The ratio of CD(34)(+) cells in MDS-RA was significantly elevated than AA patients (P < 0.05). The surface expression of G-CSFR on CD(34)(+) cells of AA, MDS patients and controls were 34.402 +/- 21.8357%, 26.376 +/- 15.2895% and 21.443 +/- 7.4465%, respectively. The surface expression of G-CSFR on CD(34)(+) cells of MDS-RA and MDS-RAEB patients were 22.788 +/- 14.7628% and 30.682 +/- 15.5346%. The surface expression of GM-CSFR on CD(34)(+) cells of AA, MDS patients and controls were 6.5961 +/- 4.4322%, 18.2737 +/- 10.9841% and 4.2753 +/- 2.6249%, respectively. Compared with AA and controls, the expression of GM-CSFR in MDS patients was significantly elevated (P < 0.05). The surface expression of GM-CSFR on CD(34)(+) cells of MDS-RA and MDS-RAEB patients were 16.1625 +/- 6.9487% and 22.1003 +/- 14.2983%. In AA patients, the ratio of CD(34)(+) cells in BMMNC less than 0.1% accounts for 75% (6/8) SAA patients, compared with 10.55% (2/19) in CAA (P < 0.05). The detection of CD(34)(+) cells and their surface expression of granulocyte (macrophage) colony-stimulating factor receptors G (M)-CSFR in AA and MDS are helpful in the differential diagnosis or prognosis of these two disorders.