Targeting nucleolin for better survival in diffuse large B-cell lymphoma

Area of Science:

• Oncology
• Molecular Biology
• Cancer Research

Background:

• Anthracyclines are vital for treating diffuse large B-cell lymphoma (DLBCL).
• The efficacy of anthracyclines relies on topoisomerase-II-alpha (TopIIA), a DNA repair enzyme.
• Nucleolin's role in DLBCL treatment resistance was previously unknown.

Purpose of the Study:

• To identify novel binding partners of TopIIA.
• To investigate the role of nucleolin in DLBCL chemoresistance.
• To explore the therapeutic potential of targeting the nucleolin-TopIIA interaction.

Main Methods:

• Identified nucleolin as a TopIIA binding partner using biochemical assays.
• Utilized gene silencing (siRNA) to abrogate nucleolin expression in DLBCL cells.
• Assessed DNA damage (γH2AX, DNA fragmentation) and apoptosis induction.
• Mapped the nucleolin-TopIIA binding interface.
• Tested the efficacy of nucleolin inhibitors (AS1411, N6L) in combination with doxorubicin.

Main Results:

• Nucleolin directly binds to TopIIA, specifically within RNA-binding domain 3.
• Abrogation of nucleolin sensitized DLBCL cells to doxorubicin and etoposide, enhancing DNA damage and apoptosis.
• Nucleolin silencing reduced TopIIA decatenation activity but increased TopIIA-DNA cleavable complex formation.
• Combined treatment with nucleolin inhibitors and doxorubicin significantly reduced DLBCL cell survival.
• Low nucleolin levels correlated with poor survival in DLBCL patients treated with R-CHOP therapy.

Conclusions:

• Nucleolin is a critical mediator of TopIIA function and confers resistance to TopIIA-targeting agents in DLBCL.
• Targeting the nucleolin-TopIIA interaction represents a promising therapeutic strategy for DLBCL.
• Nucleolin expression level is a potential prognostic biomarker for DLBCL patients.