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 elements with 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 were measured 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 control patients, respectively. Among all the cyclins expressed during the S phase, cyclin D expression was the lowest in the CML patients. Distribution of cyclins and CDKIs during the G2/M phase was similar in the MM and control groups, whereas cyclin 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 associated with elevated CDKI expression. This finding may increase our understanding of the mechanisms involved in the etiopathogenesis of hematological malignancy.