PRDI-BF1 and PRDI-BF1β Isoform Expressions Correlate with Disease Status in Multiple Myeloma Patients

Human positive regulatory domain I binding factor 1 (PRDI-BF1 or BLIMP-1) is a transcription factor that acts as a master regulator and has crucial roles in the control of differentiation and in maintaining survival of plasma cells (PC). The PRDM1 gene, which codifies for PRDI-BF1, contains an alternative promoter capable of generating a PRDI-BF1 deleted protein (called PRDI-BF1β), which lacks 101 amino acids comprising most of the regulatory domain. PRDI-BF1β has been detected in relevant quantities especially in multiple myeloma cell lines (U266 and NCI- H929). The first aim of the study was to compare, using real time polymerase chain reaction (RT-PCR), the levels of PRDI-BF1 and PRDI-BF1β in myeloma patients and in normal human bone marrow. The second step was the examination of the expression of PRDI-BF1 and PRDI-BF1β isoform depending on disease status and treatment response. We demonstrate the correlation of PRDI-BF1 and the shorter PRDI-BF1β isoform protein levels with the clinical evolution and the management of myeloma patients.