U2932 cells treated with ibrutinib and/or miR-28 in vitro
Diffuse large B cell lymphoma (DLBCL) is the most common aggressive B cell lymphoma and accounts for nearly 40% of cases of B cell non-Hodgkin lymphoma. DLBCL is generally treated with R-CHOP chemotherapy, but many patients do not respond or relapse after treatment. Here, we analyzed the therapeutic potential of the tumor suppressor microRNA-28 (miR-28) for DLBCL, alone and in combination with the Bruton's tyrosine kinase inhibitor ibrutinib. Combination therapy with miR-28 plus ibrutinib potentiated the anti-tumor effects of monotherapy with either agent by inducing a specific transcriptional cell-cycle arrest program that impairs DNA replication. The molecular actions of miR-28 and ibrutinib synergistically impair DNA replication by simultaneous inhibition of origin activation and fork progression. Moreover, we found that downregulation of the miR-28-plus-ibrutinib gene signature correlates with better survival of ABC-DLBCL patients. These results provide evidence for the effectiveness of a new miRNA-based ibrutinib combination therapy for DLBCL and unveil the miR-28-plus-ibrutinib gene signature as a new predictor of outcome in ABC-DLBCL patients. Overall design: U2932 cells transduced with pTRIPZ-scramble or pTRIPZ-miR-28 were induced with doxycycline (0.5 µg/ml) for 24 hours. Cells were then treated with 25 µM ibrutinib, while maintaining doxycycline in the medium. As a control, cells were treated with vehicle (DMSO). RFP+ cells were isolated in a FACS Aria cell sorter at 20 h after the start of ibrutinib treatment. RNA-Seq analysis was performed on two independent combined-treatment experiments.Libraries for gene expression were generated.