CLINICAL IMPLICATION OF CENTROSOME AMPLIFICATION AND EXPRESSION OF CENTROSOMAL FUNCTIONAL GENES IN MM

Sborník

Background. Multiple myeloma (MM) is an incurable plasma cell malignancy, a heterogeneous disorder with incompletely understood molecular defects and variable clinical manifestations. Genome of malignant plasma cells (PC) is extremely unstable, characterized by a combination of complex structural and numerical abnormalities. Centrosome amplification (CA) is supposed to be one of mechanisms leading to chrosomal instability. Also, CA is associated with deregulation of cell cycle, mitosis, DNA repair and proliferation. As CA is common in all plasma cell stages including MGUS, it is therefore an early event in MM and can serve as a source of genomic instability. Aims. The objective of our study was to evaluate clinical impact of CA as well as its association with changes in expression of genes involved in centrosome structure/function in MM. Methods. A total of 216 patients were evaluated for this study. Patients’ baseline characteristics were as follows: males/females (122/94), median age of 67.5 years (range 40-85 years). Newly diagnosed (123/216) and relapsed (93/216) patients were included in this study; most of them had advanced stage of MM (D-S II/III 84% [181/216]; ISS II/III 60% [129/216]). CD138+ cells were separated by MACS. Immunofluorescent labeling of centrin was used for evaluation of centrosome amplification (CA) in PCs. Interphase FISH with cytoplasmic immunoglobulin light chain staining (cIg FISH) and qRT-PCR (113/216) were performed on PCs. Results. Based on immunofluorescent staining results, all newly diagnosed patients were divided to CA positive (40%) and CA negative (60%). MM related early death in two years after diagnosis was significantly higher in CA negative group 19% (6/32) vs 0% (0/29) in CA positive (P=0.032). Also, worse OS was indicated in CA negative patients (44/73) in comparison with CA positive patients (29/73) (P=0.029). Group of newly diagnosed MM patients showed significant differences in relative quantification coefficient R of the following genes: AURKB, PLK4 and TUBG1 between CA positive (n=13) and CA negative (n=18) groups of patients (p<0.05).Total of 85% of qRT-PCR samples (96/113) were available for further analyses. Gene expression in newly diagnosed (61/96) and relapsed (35/96) patients showed significant changes of the following (AURKA, AURKB, CCNB1, CCNB2, CETN2, HMMR, PLK4, PCNT and TACC3. All mentioned genes were upregulated in PC population of relapsed patients (p<0.05).Expression of genes connected with centrosome formation and function was significantly different between HY (25/54) and non-HY (29/54) myeloma patients. AURKA was upregulated in non-HY group, while AURKB and PLK4 were upregulated in HY. Conclusions. Considering revealed clinical and gene expression heterogeneity between CA negative and CA positive patients, there is a possibility to characterize them as notable event in multiple myeloma pathogenesis. Centrosome abnormality as well as aneuploidy is spatially and timely tightly linked to the cell cycle disruption; CA triggers spindle checkpoints, leading to mitotic catastrophe and accumulation of genomic abnormalities during disease progression in MM. Acknowledgments. This work was supported by grants: NT11154, NT12130, MSM0021622434 and by project GAP304/10/1395.

Haematologica, 2012; 97(s1):  241