The Fanconi Anemia (FA)/BRCA DNA damage repair pathway plays a pivotal role in the cellular response to replicative stress induced by DNA alkylating agents and greatly influences drug response in cancer treatment. We recently reported that FA/BRCA genes are overexpressed and causative for drug resistance in human melphalan-resistant multiple myeloma (MM) cell lines. However, the transcriptional regulation of the FA/BRCA pathway is not understood. In this report, we describe for the first time a novel function of the NF-κB subunits, RelB/p50, as transcriptional activators of the FA/BRCA pathway. Specifically, our findings point to constitutive phosphorylation of IκB Kinase IKKα and subsequent alterations in FANCD2 expression and function as underlying events leading to melphalan resistance in repeatedly exposed MM cells. Inhibiting NF-κB by siRNA, blocking the IKK complex with BMS-345541, or using the proteasome inhibitor bortezomib drastically reduced FA/BRCA gene expression and FANCD2 protein expression in myeloma cells, resulting in diminished DNA damage repair and enhanced melphalan sensitivity. Importantly, we also found that bortezomib decreases FA/BRCA gene expression in multiple myeloma patients. These results show for the first time that NF-κB transcriptionally regulates the FA/BRCA pathway, and provide evidence for targeting FA-mediated DNA repair to enhance chemotherapeutic response and circumvent drug resistance in myeloma patients.

We propose a provisional model for persistence. In Q fever without sequelae, the process is largely confined to the bone marrow. In Q fever fatigue syndrome (QFS), it is modulated by the patient's immunogenetic background to give higher levels of coxiella genomes in bone marrow and increased shedding into the peripheral blood. In Q fever endocarditis, late pregnancy, or during iatrogenic or other immunosuppression, the multiplication cycle is prolonged, and a potential source of live organisms.

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