Flow Cytometric Evaluation of Cell Cycle Regulators (Cyclins and Cyclin-Dependent Kinase Inhibitors) Expressed on Bone Marrow Cells in Patients with Chronic Myeloid Leukemia and Multiple Myeloma

Objective: The aim of this study was to use flow cytometry to analyze the expression of cell cycle-regulating elementswith low and high proliferative signatures in patients with malignant diseases. Material and Methods: Cyclin D, E, A, and B, and cyclin-dependent kinase inhibitor (CDKI) p16 and p21 levels weremeasured via flow cytometry in patients with chronic myeloid leukemia (CML) (n = 16) and multiple myeloma (MM)(n = 13), and in controls (n = 15). Results: The distributions of the cell cycle S phase were 10, 63%, 6, 72% and 3, 59%; for CML, MM and controlpatients, respectively. Among all the cyclins expressed during the S phase, cyclin D expression was the lowest in the CMLpatients. Distribution of cyclins and CDKIs during the G2/M phase was similar in the MM and control groups, whereascyclin expression was similar during all 3 phases in the MM and CML groups. Conclusion: Elevated cyclin expression during cell cycle phases in the CML and MM patients was not associatedwith elevated CDKI expression. This finding may increase our understanding of the mechanisms involved in theetiopathogenesis of hematological malignancy.