The roles of SDF-1/CXCR4 axis and its relationship with apoptosis in the myelodysplastic syndromes.

We performed flow cytometric analysis of CD34(+) cell apoptosis in 22 patients with myelodysplastic syndrome (MDS) and 7 patients with de novo acute myeloid leukemia (AML) using annexin V-FITC, which binds to exposed phosphatidylserine on apoptotic cells. Apoptosis was significantly increased in low-grade MDS group (IPSS score ≤ 1.0) compared with high-grade MDS group (21.33 vs. 7.27%, P < 0.001) and patients with de novo AML (21.33 vs. 7.53%, P < 0.001). There was no correlation between apoptosis and patient's age or gender. Our results confirmed that CD34(+) cell apoptosis was significantly increased in low-grade MDS, which was featured as bone marrow failure. CXCR4 protein expression on CD34(+) cell surface in the low-grade MDS was lower than high-grade MDS (10.42 vs. 16.97, P = 0.014) and AML group (10.42 vs. 20.26, P < 0.001). But there was no statistical significance between low-grade MDS and the control group (P = 0.496). Furthermore, we measured SDF-1 levels in BM plasma from patients by enzyme-linked immunosorbent assay (ELISA), and no difference was found. We found a negative correlation between apoptosis and CXCR4 expression. Our data indicate that CXCR4 might be the prognostic marker of MDS.