OBJECTIVETo investigate the expression level of B lymphocyte-induced maturation protein-1(Blimp-1) mRNA in bone marrow mononuclear cells(BMMNC) of multiple myeloma(MM) patients and its clinical significance.

METHODSFluorescent quantitative real-time PCR(qRT-PCR) was used to measure Blimp-1 mRNA expression in BMMNC and flow cytometry(FCM) was performed to detect the number of malignant plasma cells in bone marrow of MM group (39 newly-diagnosed and untreated patients) and IDA group (5 IDA patients). The clinical data of all the patients' were collected, and the 39 patients in MM group were divided into 2 subgroups: in BD group 20 cases were treated with bortezomib-based regimen and in VOD group 19 patients were treated with VAD regimen. The age, sex, clinseal stage and type between the 2 subgroups were not statistically different. Blimp-1 mRNA expression level in BMMNC of MM patients was detected by qRT-PCR after 3 treatment cycles.

RESULTSThe expression levels of Blimp-1 mRNA in BMMNC of IDA patients and MM patients divided into 3 groups according to ISS were (0.00047±0.00027), ISS I(0.09543±0.02800), Ⅱ(0.13606±0.04162),Ⅲ (0.21202±0.03940), separately. There was statistical difference among the 4 groups(F=56.929,P<0.05) and there was significant difference between any 2 groups of these 4 groups(P<0.05). Significant positive correlation was found between Blimp-1 mRNA expression level and the number of malignant plasma cells, serum monoclonal proteins (M protein), β2-microglobulin(β2-MG), lactic dehydrogenase(LDH), C-reactive protein(CRP)(P<0.05). There was significant negative correlation between Blimp-1 mRNA and hemoglobin (Hb) level (P<0.05). After 3 cycles of chemotherapy, Blimp-1 mRNA level of patients with a >50% reduction of M protein was significantly lower than that of patients whose M protein did not decrease significantly(P<0.05). After 3 treatment cycles, Blimp-1 mRNA expression in BMMNC in BD group was significantly lower than that in VAD group [(0.02388±0.00871) vs (0.04823±0.00219), P<0.05].

CONCLUSIONThe Blimp-1 mRNA expression level in BMMNC may reflect the tumor burden in MM patients, which related with ISS, and positively correlated with the malignant plasma cell number, M protein, β2-MG, LDH, CRP level, and negatively correlated with Hb. The change of Blimp-1 mRNA expression level in BMMNC relates with the extent of M protein reduction, suggesting it may be used as a marker for response to therapy. Bortezomib may have effect on malignant plasma cells by suppressing Blimp-1 mRNA expression.