Correlation of Blimp1 with ATF4/CHOP Signaling Pathway in Multiple Myeloma U266 Cells

Abstract

To investigate whether Blimp1 plays an anti-apoptosis role in myeloma by interfering with ATF4/CHOP cell apoptosis pathway induced by endoplasmic reticulum stress, and to explore the anti-myeloma mechanism of aspirin. The bone marrow fluid of 40 newly diagnosed multiple myeloma patients without treatment and 30 control people with relatively normal bone marrow was collected. Flow cytometry was used to separated the normal and abnormal plasma cells, LV-Blimp1-RNAi (40051-2) recombinant lentivirus down-regulates the expression of Blimp-1 in U266 cell line and detected the changes of the expression of ATF4 and CHOP gene. U266 cells were stimulated by aspirin at different concentrations (0, 0.5, 2.5, 5.0 mmol/L) in vitro. Then the effect of aspirin on proliferation of U266 cells was measured by CCK-8 assay, the mRNA expression levels of Blimp1, ATF4 and CHOP in four groups were detected by real-time PCR. The expression level of Blimp1 in phenotype abnormal plasma cells was significantly increased as compared with normal cells, while the expression of ATF4 and CHOP in phenotype abnormal plasma cells was significantly decreased as compared with normal cells (P＜0.05). In the case of MOI=100, the transfection efficiency of U266 cells was beyond 80% as detected by fluorescence microscopy. Compared with blank conrol and negatine control groups, Blimp1 mRNA expression level in positive group was significantly reduced while ATF4 and CHOP expression significantly increased. CCK-8 showed that the proliferation activity of U266 cells could be inhibited by aspirin, which showed a time-and dose-dependent manner; at the same time, the expression level of Blimp1 in U266 cells were decreased with the increasing of aspirin concentration, while the expression level of ATF4 and CHOP was increased with the increasing of aspirin concentration. Blimp1 may display the anti-apoptosis of myeloma cells through interfering with ATF4/CHOP signaling pathway; low dose of aspirin may play anti-myeloma effect by inhibiting the expression of Blimp1 in myeloma cells.