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Abstract
Hypermethylation of the homeobox (HOX) gene promoter leads to decreased expression of the gene during tumor development and is thought to be correlated with the clinical outcome in leukemia. In this study, we performed pyrosequencing to quantify the methylation level of HOXA5 genes in the bone marrow samples obtained from 50 patients with AML and 19 normal controls. The methylation percentage of HOXA5 in AML patients (median=65.4%, interquartile range=35.9-72.3%) was higher than that of HOXA5 in control patients (median=43.1%, interquartile range=36.7-49.6%, Mann-Whitney U test, P=0.012). The patients of the AML group who had a high methylation percentage (>70%) had a good prognosis with a 3-yr overall survival (OS) of 82.5%, whereas the patients with a low methylation percentage (≤70%) showed a 3-yr OS of 40.5% (P=0.048). Cox proportional hazards regression showed that the methylation percentages of HOXA5 were independently associated with the 3-yr OS of AML patients, regardless of their karyotypes. We propose that the quantification of HOXA5 methylation by pyrosequencing may be useful for predicting short-term prognosis in AML. However, the limitations of our study are the small sample size and its preliminary nature. Thus, a larger study should be performed to clearly determine the relationships among HOXA5 methylation levels, cytogenetics, and prognosis in AML patients.
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Fig. 1.
ROC curve analysis showed that a cut-off of 70% HOXA5 methylation yielded sensitivity and specificity of 60% and 100%, respectively.
Fig. 2.
Percentage of 3-yr overall survival of patients with “mean HOXA5 methylation percentage greater than 70%” and of those with “mean HOXA5 methylation less than 70%”.
Table 1.
Characteristics of AML patients according to HOXA5 methylation
| Mean of MtP | P value | ||
|---|---|---|---|
| Less than 70% (N=32) | More than 70% (N=18) | ||
| Age (mean±SD) | 51.9±14.2 | 47.1±16.5 | 0.201 |
| Sex (%) | |||
| Male | 15 (46.9) | 13 (72.2) | |
| Female | 17 (53.1) | 5 (27.8) | |
| FAB classification (%) | 0.452 | ||
| AML, unclassified | 3 (9.3) | 0 (0.0) | |
| M0 | 2 (6.3) | 0 (0.0) | |
| M1 | 7 (21.9) | 7 (38.9) | |
| M2 | 9 (28.1) | 3 (16.7) | |
| M3 | 4 (12.5) | 6 (33.3) | |
| M4 | 5 (15.6) | 1 (5.6) | |
| M5 | 1 (3.1) | 1 (5.6) | |
| M6 | 1 (3.1) | 0 (0.0) | |
| Karyotyping (%) | 0.004 | ||
| Unfavorable | 4 (12.5) | 3 (17.6) | |
| Intermediate | 24 (75.0) | 5 (29.4) | |
| Favorable | 4 (12.5) | 9 (52.9) | |
| Normal karyotype | 17 (70.8) | 4 (80.0) | 1.000 |
| (%) among | |||
| intermediate group | |||
| Chemotherapy | 0.114 | ||
| regimens (%) | |||
| AI | 25 (78.1) | 9 (50.0) | |
| AIDA | 4 (12.5) | 6 (33.3) | |
| Other | 3 (9.4) | 3 (16.7) | |
| LDH (mean±SD)∗ | 1,597.5±1,464.6 1,458.9±1,505.3 | 0.303 | |
| Hb (mean±SD)∗ | 8.5±1.5 | 8.5±1.2 | 0.973 |
| WBC (×103/μL, mean±SD)∗ | 29.5±60.6 | 38.0±67.7 | 0.412 |
Table 2.
Cox proportional hazard regression analysis for 3-yr overall survival of AML patients
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