Dysregulated MDR1 by PRDM1/Blimp1 Is Involved in the Doxorubicin Resistance of Non-Germinal Center B-Cell-Like Diffuse Large B-Cell Lymphoma

Chemotherapy. 2022;67(1):12-23. doi: 10.1159/000520070. Epub 2021 Nov 29.

Abstract

Introduction: The chemoresistance mechanism of diffuse large B-cell lymphoma (DLBCL) is still poorly understood, and patient prognosis remains unsatisfactory. This study aimed to investigate drug resistance mechanisms in non-germinal center B-cell-like (non-GCB) DLBCL.

Methods: Doxorubicin (DOX)-resistant OCI-Ly3 cells were generated through long-term incubation of cells in a medium with gradually increasing DOX concentrations. The expression levels of genes related to drug metabolism were determined using a functional gene grouping polymerase chain reaction (PCR) array. Drug-resistant proteins were identified using bioinformatics, and molecular association networks were subsequently generated. The association and mechanism of key genes were determined using a dual-luciferase reporter assay System and chromatin immunoprecipitation (ChIP). The expression of drug-resistant genes and target genes was then measured using Western blotting and immunohistochemistry. The correlation between gene expressions was analyzed using Spearman's rank correlation coefficient.

Results: Using the PCR array, MDR1 was identified as the key gene that regulates DOX resistance in OCI-Ly3/DOX-A100, a non-GCB DLBCL cell line. The dual-luciferase reporter assay system demonstrated that MDR1 transcription could be inhibited by PRDM1. ChIP results showed that PRDM1 had the ability to bind to the promoter region (-1,132 to -996) of MDR1. In OCI-Ly3/DOX cells, NF-κB activity and PRDM1 expression decreased with an increase in drug-resistant index, whereas MDR1 expression increased with enhanced drug resistance. Immunohistochemical analysis revealed that relative MDR1 expression was higher than that of PRDM1 in human DLBCL tissue samples. A negative correlation was observed between MDR1 and PRDM1.

Conclusion: In non-GCB DLBCL cells, NF-κB downregulates PRDM1 and thereby promotes MDR1 transcription by terminating PRDM1-induced transcriptional inhibition of MDR1. Such a mechanism may explain the reason for disease recurrence in non-GCB DLBCL after R-CHOP or combined CHOP with bortezomib treatment. Our findings may provide a potential therapeutic strategy for reducing drug resistance in patients with DLBCL.

Keywords: Doxorubicin; Drug resistance; NF-κB; Non-Hodgkin’s lymphoma; PRDM1 gene.

MeSH terms

  • ATP Binding Cassette Transporter, Subfamily B / genetics
  • Antineoplastic Combined Chemotherapy Protocols / therapeutic use
  • Doxorubicin* / pharmacology
  • Doxorubicin* / therapeutic use
  • Drug Resistance, Neoplasm* / genetics
  • Gene Expression Regulation*
  • Humans
  • Lymphoma, Large B-Cell, Diffuse* / drug therapy
  • Lymphoma, Large B-Cell, Diffuse* / genetics
  • Neoplasm Recurrence, Local* / drug therapy
  • Positive Regulatory Domain I-Binding Factor 1* / genetics
  • Positive Regulatory Domain I-Binding Factor 1* / metabolism
  • Prognosis
  • Rituximab / therapeutic use

Substances

  • ABCB1 protein, human
  • ATP Binding Cassette Transporter, Subfamily B
  • PRDM1 protein, human
  • Rituximab
  • Doxorubicin
  • Positive Regulatory Domain I-Binding Factor 1