Chromosomal Instability Triggered by Rrm2b Loss Leads to IL-6 Secretion and Plasmacytic Neoplasms

• Constitutive NF-κB and STAT3 mediate sustained IL-6 expression in Rrm2b-deficient cells
• Loss of the Rrm2b gene causes chromosomal instability
• Mice deficient in Rrm2b exhibit elevated IL-6 and hematologic disorders
• IL-6 deficiency delays disease onset and mortality of Rrm2b−/− mice

SummaryChronic inflammation has a tight cause-and-effect relationship with DNA damage by inflicting tissue damage and increasing cancer risk. Rrm2b, a key enzyme in de novo deoxyribonucleotide synthesis, is involved in DNA damage repair, but its role in cancer development has yet to be demonstrated. In this work, Rrm2b gene loss led to severe numerical and structural chromosome abnormalities that caused ATM activation, inducing p-Ser85 IKKγ/NEMO and IκB kinase (IKK). NF-κB consequently induced by IKK triggered sustained IL-6 expression that constitutively activated STAT3 in Rrm2b-deficient cells. High plasma interleukin-6 (IL-6) and associated hematologic disorders were observed in Rrm2b−/− mice, and 30%–40% of aged Rrm2b heterozygous knockout mice developed plasma cell neoplasms and suffered from progressive splenomegaly and ascites. The genetic ablation of IL-6 suppressed STAT3 induction and delayed disease onset in Rrm2b−/− mice, extending their lifespan. Thus, Rrm2b plays a crucial role in maintaining chromosomal stability and preventing chronic-inflammation-associated tumorigenesis.

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