Centrosome Aberrations in Bone Marrow Cells From Patients with Myelodysplastic Syndromes Correlate with Chromosomal Instability

Abstract

3839 Introduction: Centrosomes play important roles in maintenance of genetic stability and centrosomal aberrations are a common hallmark of cancer. Deregulation of centriole duplication during the cell cycle leads to supernumerary centrosomes, sister chromatide missegregation and could result in chromosomal instability (CIN) and aneuploidy. CIN is a common feature in at least 50% of patients with myelodysplastic syndromes (MDS). Therefore, we sought to investigate the centrosomal status and its role for development of CIN in bone marrow (BM) cells of MDS patients. Furthermore, deregulation of the protease Separase is known as a driver of aneuploidy. It is considered as one of the master key players in centriole duplication and overexpression has been associated with the formation of supernumerary centrosomes in many cancers. Therefore, deregulated Separase could also serve as a marker for genetic instability and was investigated. Patients and methods: BM cells of 34 MDS patients were cytogenetically examined by G-banding technique. Furthermore, cells were immunostained with a centrosome-specific antibody to pericentrin followed by a Cy3-conjugated secondary antibody to analyze the centrosomal status. Umbilical cord blood specimens (CB; n=15) served as controls. In addition, Separase protein levels were analyzed in BM cells of four MDS patients and in CB cells of four healthy controls. Results: BM cells of all MDS patients displayed centrosome alterations as compared with corresponding controls. Centrosome abnormalities were detected in 10% (range, 4–17%) of analyzed cells of MDS patients but in only 2% (range, 0–4%) of cells of healthy donors (p≤0.0001). Normal karyotypes were found in all CB metaphases and in BM metaphases of 16/34 MDS patients. The incidence of centrosomal alterations was higher in bone marrow cells of patients with cytogenetic alterations (mean, 12%) compared to BM cells of patients without cytogenetic changes (mean, 7%). In BM cells of MDS patients Separase protein levels were lower (60% decrease) as compared to CB cells of the healthy control (p≤0.01). Conclusions: We could show that centrosome aberrations in BM cells of MDS patients occur before chromosomal changes are detectable. Therefore, centrosomal instability is an early step in MDS and may contribute to the acquisition of chromosomal alterations. Increase of aberrant centrosomes significantly correlates with karyotype instability and aneuploidy. It seems that centrosomal instability precedes karyotype instability via chromosomal missegregation and could contribute to the development of chromosomal changes and accelerate malignant transformation. Separase is one of the master key players in centriole duplication and chromatide segregation. Therefore, deregulated Separase could lead to genetic instability and malignant transformation. In future studies centrosomal alterations may serve as an additional prognostic biomarker for future diagnostics in MDS. Disclosures: No relevant conflicts of interest to declare.