P15INK4b gene methylation and myelodysplastic syndromes

Myelodysplastic syndromes (MDS) are clonal disorders, which frequently undergo leukemic transformation. It was recently shown that the promoter of the p15INK4b but not the p16INK4a gene is frequently and selectively hypermethylated in MDS. The p15INK4b gene is a cyclin dependent kinase inhibitor gene, which is actively transcribed after TGFbeta exposure. Methylation of the p15INK4b gene is significantly correlated with blastic bone marrow involvement, and sequential analyses have shown that methylation increases with disease evolution toward AML. These data strongly suggest that p15INK4b gene methylation is a mechanism allowing leukemic cells to escape to inhibitory signals from the bone marrow environment, however the exact role of p15INK4b gene methylation in disruption of the signal mediated by TGFbeta remains to be investigated.     

p14ARF, p15INK4b and p16INK4a methylation status in chronic myelogenous leukemia

The INK4 family of proteins p15^INK4b, p14^ARF and p16^INK4a function as cell cycle inhibitors where they are involved in the inhibition of G1 phase progression. Methylation of the p15^INK4b promoter never seems to occur in solid tumors but is a major gene silencing mechanism in hematological malignancies. p14^ARF and p16^INK4a promoter methylation often occurs in solid tumors but also in leukemias and lymphomas. In chronic myelogenous leukemia (CML), only a few reports have been published regarding INK4 methylation and the results of the literature are discordant. Thus clearly, more works on large series have to be performed independently.     

Methylation status of the p15INK4B gene in hematopoietic progenitors and peripheral blood cells in myelodysplastic syndromes.

We previously reported that the hypermethylation of the p15INK4B gene promoter was frequently observed in myelodysplastic syndromes (MDS), and that it may be associated with disease progression. An unanswered question is whether p15INK4B gene methylation is restricted to undifferentiated blastic cells, or whether differentiated cells such as granulocytes or erythrocytes of MDS origin also harbor this epigenetic alteration. In this study, we analyzed the methylation status of the p15INK4B gene in MDS by the methylation-specific PCR (MSP) method, which is more sensitive than Southern blotting. The bone marrow mononuclear cells (BM-MNCs) of 23 MDS patients were analyzed, and six of them showed p15INK4B methylation. Progenitor assay with methylcellulose medium was also performed in all patients. In two of the six patients with p15INK4B-methylated BM-MNCs, erythroid and/or non-erythroid colonies formed were subjected to molecular analysis. Colonies with and without p15INK4B methylation were detected in both patients. Furthermore, X-chromosome inactivation (XCI) pattern of each colony was simultaneously determined by MSP-based human androgen receptor gene analysis (HUMARA-MSP), and all p15INK4B-methylated colonies showed the same XCI pattern, which was dominant among the colonies, while p15INK4B-unmethylated colonies showed both patterns of XCI, in each of the two patients. We then examined the methylation status of the p15INK4B gene of granulocyte (PB-PMN) fractions from 10 patients with available peripheral blood cells. In all four patients with p15INK4B-methylated BM-MNCs, their PB-PMNs showed p15INK4B methylation. These results suggest that p15INK4B methylation in hematopoietic cells in MDS patients is restricted to the MDS clone but not necessarily to blast cells.     

Expression and methylation status of the FHIT gene in acute myeloid leukemia and myelodysplastic syndrome.

To clarify the role of fragile histidine triad (FHIT) in hematological malignancies, we examined the methylation status and the expression level of the FHIT gene in myelodysplastic syndrome (MDS) and acute myeloid leukemia (AML) cells in comparison with the methylation of the p15(INK4B) gene. The FHIT methylation was found in 13 of 94 (13.8%) AML and 22 of 40 (55.0%) MDS cases, but not in normal mononuclear cells (MNCs). Both the frequency and density of methylation increased in the advanced-stages MDS and the relapsed AML cases. Although FHIT and p15(INK4B) methylations were not correlated in MDS and AML, increased FHIT methylation at the relapse in AML was associated with p15(INK4B) methylation. The median expression level in AML was significantly higher than in normal MNCs, although the median expression level in those with methylation was significantly lower than in those without methylation. Furthermore, the methylation level at relapse was significantly higher than at diagnosis in AML. These results suggested that FHIT methylation was accumulated through the disease progression of MDS and AML, and the role of the FHIT gene as a tumor suppressor seemed different in AML and MDS.     

Low-dose cytosine arabinoside in the myelodysplastic syndromes and acute myelogenous leukemia

Seven patients with a myelodysplastic syndrome or "smoldering" acute myelogenous leukemia were treated with cytosine arabinoside in low dosage. Four patients experienced transient, partial responses characterized by improved peripheral blood counts, cessation of transfusion requirements, and a decreased incidence of infection. Treatment was associated with significant, transient hematologic toxicity. The appropriate clinical role of low-dose cytosine arabinoside remains uncertain.     

Aberrant methylation and impaired expression of the p15(INK4b) cell cycle regulatory gene in chronic myelomonocytic leukemia (CMML).

The important cell cycle regulatory gene p15(INK4b) has been shown to be inactivated in acute myeloid leukemia and myelodysplastic syndrome. Little is known about the expression and epigenetic modification of this gene in chronic myelomonocytic leukemia (CMML) that belongs to the myelodysplastic/myeloproliferative disorders (MDS/MPD) with a high proportion of blastic transformation. Analysis of bone marrow trephines in a series of 33 CMML cases showed an aberrant p15(INK4b) gene methylation in up to 58% of cases. Methylation was analyzed employing different methylation-specific PCR and genomic sequencing protocols. It turned out to be spread over a broad area of the 5' region and exhibited substantial heterogeneity between cases and even in individual patients. The degree of aberrant methylation was correlated with a reduced mRNA as well as reduced protein expression, and was associated with a higher expression of DNA methyltransferase DNMT 3A. We conclude that aberrant gene methylation is a frequent event in CMML that might contribute to the pathogenesis of this MDS/MPD.     

Analysis of the methylation patterns of the p16 INK4A , p15 INK4B , and APC genes in gastric adenocarcinoma patients from a Brazilian population

Gastric cancer is a major public health problem in Pará state, where studies suggest complex genetic and epigenetic profiles of the population, indicating the need for the identification of molecular markers for this tumor type. In the present study, the methylation patterns of three genes [p16 ^INK4A , p15 ^INK4B , and adenomatous polyposis coli (APC)] were assessed in patients with gastric adenocarcinoma from Pará state in order to identify possible molecular markers of gastric carcinogenesis. DNA samples from tumoral and non-tumoral gastric tissues were modified with sodium bisulfite. A fragment of the promoter region of each gene was amplified and sequenced, and samples with more than 20 % of methylated CpG sites were considered hypermethylated. The correlation between the methylation pattern of the selected genes and the MTHFR C677T polymorphism, as well as the relationship between APC and CDH1 methylation, were evaluated. The results suggest that APC hypermethylation is an age-specific marker of gastric carcinogenesis, and the concordance of this event with CDH1 hypermethylation suggests that the Wnt pathway has an important role in gastric carcinogenesis. While the hypermethylation pattern of p15 ^INK4B seems to be an earlier event in this type of tumor, the hypomethylated status of this gene seems to be correlated to the C677T MTHFR TT genotype. On the other hand, the observed pattern of p16 ^INK4A hypermethylation suggests that this event is a good marker for the gastric cancer pathway in the Pará state population.     

FHIT对急性髓系白血病细胞HL60影响的研究

目的:进行外源FHIT基因转染人白血病细胞缺乏FHIT表达的HL60,研究FHIT基因对转染细胞生长的生物学影响。方法:构建pEGFP-FHIT真核表达质粒（实验组）与质粒pEGFP-N1（对照组）。分别电穿孔法转染HL60细胞。应用荧光显微镜、RT-PCR、Western blot检测转染基因的转录和表达情况。四甲基偶氮唑盐（MTT）法、流式细胞术研究转染基因对HL60细胞体外增殖、凋亡情况的影响,并与转染对照质粒的细胞株进行比较。结果:经PCR、酶切和DNA测序证实pEGFP-FHIT真核载体构建成功。荧光显微镜下实验组HL60细胞可见绿色荧光,转染率为40%。RT-PCR和Western blot分别从mRNA和蛋白水平检测到FHIT的表达。MTT检测结果显示:转染后实验组抑制率明显升高,细胞增殖受到抑制（P＜0.05）。流式细胞术结果显示:实验组细胞凋亡率明显增加（P＜0.05)。结论:转染FHIT基因对白血病细胞HL60的生长有抑制作用,并能诱导其凋亡。     

Cognitive impairment, fatigue, and cytokine levels in patients with acute myelogenous leukemia or myelodysplastic syndrome

BACKGROUND: The objective of the current study was to assess the correlations between cognitive function, fatigue, quality of life, and circulating cytokine levels in patients with acute myelogenous leukemia (AML) and myelodysplastic syndrome (MDS). METHODS: Fifty-four patients with AML/MDS were seen for pretreatment evaluation of their cognitive function and symptoms. Fifty percent of the sample was reevaluated 1 month later, when response to protocol chemotherapy was assessed. RESULTS: A significant proportion of patients had impaired cognitive function prior to the institution of chemotherapy. Sixty-five percent of patients also experienced significant fatigue. Levels of the circulating cytokines interleukin 1 (IL-1), IL-1 receptor antagonist (IL-1RA), IL-6, IL-8, and tumor necrosis factor-alpha (TNF-alpha) were elevated highly compared with normal controls. Higher IL-6 levels were associated with poorer executive function, whereas higher IL-8 levels were associated with better memory performance. IL-6, IL-1RA, and TNF-alpha levels were related to ratings of fatigue. Fatigue and cognitive dysfunction were unrelated. Hemoglobin levels were not associated significantly with either cognitive dysfunction or fatigue. Patients who obtained a complete response tended to have better fine motor control at baseline and lower circulating IL-1 levels. Treatment did not have a significant impact on cognition, although fatigue levels tended to increase. CONCLUSIONS: Patients with AML/MDS are highly symptomatic and experience cognitive impairment and fatigue before the initiation of their treatment. The current results indicated a correlation between these symptoms and levels of circulating cytokines, providing some support to the hypothesis that cancer-related symptoms are related at least in part to cytokine-immunologic activation. Elucidation of immunologic correlates of symptoms will allow for targeted interventions.     

Activation of ras oncogene in myelodysplastic syndrome and acute myelogenous leukemia

N-ras oncogenes activated by point mutation have been frequently detected in various types of human leukemias. Analysis of a large number of leukemias revealed that activated N-ras oncogenes were observed preferentially in AML, AMoL, T-ALL and Null-ALL but rarely in CML and B-cell leukemia. These results suggest that N-ras oncogene plays an important role in human leukemogenesis. Activated N-ras oncogenes were also detected in myelodysplastic syndrome (MDS) that is considered to be a preleukemic disease. MDS patients bearing an activated N-ras oncogene frequently showed leukemic progression of the disease, suggesting that an activated N-ras oncogene can be a critical factor for prognosis of MDS patients. Thus, detection of an activated N-ras oncogene is useful for diagnosis, prognostic evaluation and therapeutic decision. Recently, we demonstrated that detection of the minimal residual disease by analysis of N-ras oncogene can lead to improvement of the remission rate in leukemias. Moreover, we made it possible to screen N-ras oncogene by a sensitive non-radioactive method. Our research procedure seems to be a good model for clinical application of the molecular biological technique.     

Chromosome pattern in juvenile chronic myelogenous leukemia, myelodysplastic syndrome, and acute leukemia associated with neurofibromatosis

We studied chromosomes of BM cells from four neurofibromatosis (NF) patients with leukemia. One patient had a normal diploid karyotype in the chronic phase of juvenile chronic myelogenous leukemia (JCML). When the the leukemia evolved into the accelerated phase, she had cells with 46,XX,-7,+der(7)t(3;7)(q21;p22); the abnormalities resulted in a partial 7p deletion. In another patient with JCML, BM cells in the accelerated phase had 45,XY,-7. The abnormal cells with monosomy 7 disappeared from the BM after chemotherapy but reappeared later in the course. Another patient developed refractory anemia with excess of blasts in transformation (RAEB-T) and had cells with 46,XX,-6,+r(6)(p23?q21?); the abnormalities resulted in partial 6p and 6q deletions. The other patient with ANLL had cells with 45,XX,-7. Our findings and review of data on nine other patients suggest that BM cells of NF patients with JCML in chronic phase have no microscopically detectable chromosome changes and that cells with chromosomal deletion emerge when JCML evolve into the accelerated or blast phase. Thus, deletion of the whole or part of certain chromosomes, such as chromosomes 6, 7, etc., may be an important step towards the evolution of JCML cells or the development of de novo acute leukemias in NF patients.     

低剂量亚砷酸及维甲酸方案对儿童骨髓增生异常综合征p15INK4B基因的影响

目的 探讨低剂量亚砷酸及维甲酸双诱导方案对骨髓增生异常综合征(MDS)患儿p15INK44B基因表达的影响及患儿p15INK4B基因甲基化水平的变化.方法 11例MDS患儿接受低剂量亚砷酸及维甲酸双诱导方案治疗,应用实时荧光定量聚合酶链反应(PCR)方法检测治疗前后p15INK4B基因的表达,应用亚硫酸氢钠修饰及实时荧光定量PCR方法检测p15INK4B基因的甲基化水平.结果 11例MDS患儿经过双诱导方案治疗后,9例获益.治疗后10例患儿p15INK4B基因表达水平显著升高,治疗前后p15INK4B基因甲基化水平分别为(1.68±0.58)％、(1.44±0.65)％,二者差异无统计学意义(t=-0.885,P＞0.05).结论 低剂量亚砷酸及维甲酸双诱导方案治疗儿童MDS疗效较好,该方案的作用机制可能与p15INK4B基因表达升高有关,但p15INK4B基因表达升高与去甲基化无相关性.     

Phase I trial of sodium salicylate in patients with myelodysplastic syndromes and acute myelogenous leukemia

Sodium salicylate is an inexpensive, readily available anti-inflammatory agent which inhibits NF-κB in in vitro models. We examined whether it was possible to safely achieve and maintain salicylate levels known to inhibit NF-κB in vitro in 11 patients with MDS or AML taking sodium salicylate. Most patients achieved the target blood salicylate level (20-30mg/dL) with acceptable toxicity, including reversible grade 1/2 elevations of hepatic transaminases (n=4) and ototoxicity (n=4). One patient had grade 3/4 elevations in AST/ALT. This study suggests that sodium salicylate may be safely combined with conventional chemotherapy regimens which are not associated with significant ototoxicity or hepatotoxicity.     

CD34+ cells from acute myeloid leukemia, myelodysplastic syndromes, and normal bone marrow display different apoptosis and drug resistance-associated phenotypes.

Myelodysplastic syndromes and acute myeloid leukemia (AML) are heterogeneous disorders in which conflicting results in apoptosis and multidrug resistance (MDR) have been reported. We have evaluated by multiparameter flow cytometry the expression of apoptosis- (APO2.7, bcl-2, and bax) and MDR-related proteins [P-glycoprotein (P-gp), multidrug resistance protein (MRP), and lung resistance protein (LRP)] specifically on bone marrow (BM) CD34+ cells, and their major CD32-/dim and CD32+ subsets, in de novo AML (n=90), high-risk myelodysplastic syndrome (n=9), and low-risk myelodysplastic syndrome (n=21) patients at diagnosis, and compared with normal BM CD34+ cells (n=6). CD34+ myeloid cells from AML and high-risk myelodysplastic syndrome patients displayed higher expression of bcl-2 (P <0.0001) and lower reactivity for APO2.7 (P=0.002) compared with low-risk myelodysplastic syndrome and normal controls. Similar results applied to the two predefined CD34+ myeloid cell subsets. No significant differences were found in the expression of P-gp, MRP, and LRP between low-risk myelodysplastic syndrome patients and normal BM, but decreased expression of MRP (P <0.03) in AML and high-risk myelodysplastic syndromes and P-gp (P=0.008) in high-risk myelodysplastic syndromes were detected. Hierarchical clustering analysis showed that low-risk myelodysplastic syndrome patients were clustered next to normal BM samples, whereas high-risk myelodysplastic syndromes were clustered together and mixed with the de novo AML patients. In summary, increased resistance to chemotherapy of CD34+ cells from both AML and high-risk myelodysplastic syndromes would be explained more appropriately in terms of an increased antiapoptotic phenotype rather than a MDR phenotype. In low-risk myelodysplastic syndromes abnormally high apoptotic rates would be restricted to the CD34- cell compartments.