High PRAME expression is associated with poor survival and early disease progression in myelodysplastic syndromes with a low bone marrow blast percentage.

We investigated the clinical implications of preferentially expressed antigen in melanoma (PRAME) expression in bone marrow cells of 116 patients with myelodysplastic syndromes (MDS). Quantitative RT-PCR was carried out to examine the PRAME expression level. High PRAME expression was observed in MDS patients classified into higher revised International Prognostic Scoring System (IPSS-R) risk categories (Very high and High) with a high bone marrow blast percentage (5% or higher). Kaplan-Meier analysis demonstrated that high PRAME expression is significantly associated with a poorer overall survival (OS) in MDS patients with a low bone marrow blast percentage (less than 5%) (log-rank test p = .0014) and those classified into lower IPSS-R risk categories (Very Low, Low, and Intermediate) (log-rank test, p = .0035). In contrast, there was no significant association between PRAME expression and OS in MDS patients with a high bone marrow blast percentage or those classified into higher IPSS-R risk categories. In addition, high PRAME expression was associated with early disease progression in MDS patients with a low bone marrow blast percentage. This study suggested PRAME expression to be a prognostic factor in MDS.

Expression analysis of genes located within the common deleted region of del(20q) in patients with myelodysplastic syndromes.

Deletion of the long arm of chromosome 20 (del(20q)) is observed in 5-10% of patients with myelodysplastic syndromes (MDS). We examined the expression of 28 genes within the common deleted region (CDR) of del(20q), which we previously determined by a CGH array using clinical samples, in 48 MDS patients with (n = 28) or without (n = 20) chromosome 20 abnormalities and control subjects (n = 10). The expression level of 8 of 28 genes was significantly reduced in MDS patients with chromosome 20 abnormalities compared to that of control subjects. In addition, the expression of BCAS4, ADA, and YWHAB genes was significantly reduced in MDS patients without chromosome 20 abnormalities, which suggests that these three genes were commonly involved in the molecular pathogenesis of MDS. To evaluate the clinical significance, we analyzed the impact of the expression level of each gene on overall survival (OS). According to the Cox proportional hazard model, multivariate analysis indicated that reduced BCAS4 expression was associated with inferior OS, but the difference was not significant (HR, 3.77; 95% CI, 0.995-17.17; P = 0.0509). Functional analyses are needed to understand the biological significance of reduced expression of these genes in the pathogenesis of MDS.

L265P mutation of the MYD88 gene is frequent in Waldenström's macroglobulinemia and its absence in myeloma.

L265P mutation in the MYD88 gene has recently been reported in Waldenström's macroglobulinemia; however the incidence has been different according to the methods used. To determine the relevance and compare the incidence by different methods, we analyzed the L265P mutation in bone marrow mononuclear cells from lymphoid neoplasms. We first performed cloning and sequencing in 10 patients: 8 Waldenström's macroglobulinemia; 1 non-IgM-secreting lymphoplasmacytic lymphoma; and 1 low grade B-cell lymphoma with monoclonal IgG protein. The L265P mutation was detected in only 1/8 Waldenström's macroglobulinemia patients (2 of 9 clones). To confirm these results, direct sequencing was performed in the 10 patients and an additional 17 Waldenström's macroglobulinemia patients and 1 lymphoplasmacytic lymphoma patient. Nine of 28 patients (7/25 Waldenström's macroglobulinemia, 1/2 lymphoplasmacytic lymphoma, and B-cell lymphoma) harbored the mutation. We next tested for the mutation with BSiE1 digestion and allele-specific polymerase chain reaction in the 28 patients and 38 patients with myeloma. Aberrant bands corresponding to the mutation were detected by BSiE1 digestion in 19/25 patients with Waldenström's macroglobulinemia (76%), 1/2 lymphoplasmacytic lymphoma and B-cell lymphoma, but not in the 38 myeloma patients. The L265P mutation was more frequent in patients with Waldenström's macroglobulinemia than in those with myeloma (p=1.3x10(-10)). The mutation was detected by allele-specific polymerase chain reaction in 18/25 Waldenström's macroglobulinemia patients (72%). In the 25 Waldenström's macroglobulinemia patients, the L265P was more frequently detected by BSiE1 digestion than by direct sequencing (p=5.3x10(-4)), and in males (15/16, 94%) than in females (4/9, 44%) (p=1.2x10(-2)). No siginificant difference was observed in the incidence of the L265P mutation between BSiE1 digestion and allele-specific polymerase chain reaction (p=0.32). These results suggest that the L265P mutation is involved in the majority of Waldenström's macroglobulinemia. BSiE1 digestion and allele-specific polymerase chain reaction may detect a small fraction of mutated cells in some cases.

Aberrant methylation of the RIZ1 gene in myelodysplastic syndrome and acute myeloid leukemia.

We performed methylation specific PCR analysis on the RIZ1 promoter in MDS and AML. Methylation was detected in 17 of 34 MDS (50%) and 22 of 72 AML (31%) (p=0.053). Methylation was detected in eleven of 17 secondary AML from MDS (65%), and eleven of 55 de novo AML (20%) (p=0.0005). Bisulfite sequence revealed methylation at many CpG sites in the promoter. Decreased RIZ1 expression was accompanied by methylation in six of nine samples examined, while it was also observed in seven of 13 without methylation. Treatment of AML cells, that have RIZ1 methylation, with 5-Aza-dC, induced growth suppression with RIZ1 restoration. Our results suggest that the RIZ1 gene is inactivated in MDS and AML in part by methylation, whereas another mechanism should be involved in others.