Molecular pathophysiology of Diamond-Blackfan anemia (DBA) involves disrupted erythroid-lineage proliferation, differentiation and apoptosis; with the activation of p53 considered as a key component. Recently, oxidative stress was proposed to play an important role in DBA pathophysiology as well. CRISPR/Cas9-created Rpl5- and Rps19-deficient murine erythroleukemia (MEL) cells and DBA patients' samples were used to evaluate proinflammatory cytokines, oxidative stress, DNA damage and DNA damage response. We demonstrated that the antioxidant defense capacity of Rp-mutant cells is insufficient to meet the greater reactive oxygen species (ROS) production which leads to oxidative DNA damage, cellular senescence and activation of DNA damage response signaling in the developing erythroblasts and altered characteristics of mature erythrocytes. We also showed that the disturbed balance between ROS formation and antioxidant defense is accompanied by the upregulation of proinflammatory cytokines. Finally, the alterations detected in the membrane of DBA erythrocytes may cause their enhanced recognition and destruction by reticuloendothelial macrophages, especially during infections. We propose that the extent of oxidative stress and the ability to activate antioxidant defense systems may contribute to high heterogeneity of clinical symptoms and response to therapy observed in DBA patients.

• Keywords
• 8-oxoguanine, DNA damage response, Diamond-Blackfan anemia, erythrocyte lifespan, inflammatory cytokines, reactive oxygen species,
• MeSH
• Anemia, Diamond-Blackfan immunology   metabolism   pathology   MeSH
• Child MeSH
• Adult MeSH
• Erythrocytes metabolism   pathology   MeSH
• Middle Aged MeSH
• Humans MeSH
• Inflammation Mediators metabolism   MeSH
• Young Adult MeSH
• Mice MeSH
• Follow-Up Studies MeSH
• Oxidative Stress * MeSH
• DNA Damage * MeSH
• Prognosis MeSH
• Case-Control Studies MeSH
• Inflammation immunology   metabolism   pathology   MeSH
• Animals MeSH
• Check Tag
• Child MeSH
• Adult MeSH
• Middle Aged MeSH
• Humans MeSH
• Young Adult MeSH
• Male MeSH
• Mice MeSH
• Female MeSH
• Animals MeSH
• Publication type
• Journal Article MeSH
• Names of Substances
• Inflammation Mediators MeSH

Inflammatory and oncogenic signaling converge in disease evolution of BCR-ABL-negative myeloproliferative neoplasms, clonal hematopoietic stem cell disorders characterized by gain-of-function mutation in JAK2 kinase (JAK2V617F), with highest prevalence in patients with polycythemia vera (PV). Despite the high risk, DNA-damaging inflammatory microenvironment, PV progenitors tend to preserve their genomic stability over decades until their progression to post-PV myelofibrosis/acute myeloid leukemia. Using induced pluripotent stem cells-derived CD34+ progenitor-enriched cultures from JAK2V617F+ PV patient and from JAK2 wild-type healthy control, CRISPR-modified HEL cells and patients' bone marrow sections from different disease stages, we demonstrate that JAK2V617F induces an intrinsic IFNγ- and NF-κB-associated inflammatory program, while suppressing inflammation-evoked DNA damage both in vitro and in vivo. We show that cells with JAK2V617F tightly regulate levels of inflammatory cytokines-induced reactive oxygen species, do not fully activate the ATM/p53/p21waf1 checkpoint and p38/JNK MAPK stress pathway signaling when exposed to inflammatory cytokines, suppress DNA single-strand break repair genes' expression yet overexpress the dual-specificity phosphatase (DUSP) 1. RNAi-mediated knock-down and pharmacological inhibition of DUSP1, involved in p38/JNK deactivation, in HEL cells reveals growth addiction to DUSP1, consistent with enhanced DNA damage response and apoptosis in DUSP1-inhibited parental JAK2V617F+ cells, but not in CRISPR-modified JAK2 wild-type cells. Our results indicate that the JAK2V617F+ PV progenitors utilize DUSP1 activity as a protection mechanism against DNA damage accumulation, promoting their proliferation and survival in the inflammatory microenvironment, identifying DUSP1 as a potential therapeutic target in PV.

• MeSH
• Cytokines genetics   metabolism   MeSH
• Dual Specificity Phosphatase 1 genetics   MeSH
• Hematopoietic Stem Cells pathology   MeSH
• Induced Pluripotent Stem Cells pathology   MeSH
• Janus Kinase 2 genetics   MeSH
• Humans MeSH
• Mutation MeSH
• Cell Line, Tumor MeSH
• Tumor Microenvironment MeSH
• Oxidative Stress * MeSH
• Polycythemia Vera genetics   MeSH
• DNA Damage * MeSH
• Cell Proliferation * MeSH
• Reproducibility of Results MeSH
• STAT1 Transcription Factor metabolism   MeSH
• Inflammation metabolism   MeSH
• Check Tag
• Humans MeSH
• Publication type
• Journal Article MeSH
• Research Support, Non-U.S. Gov't MeSH
• Names of Substances
• Cytokines MeSH
• DUSP1 protein, human MeSH Browser
• Dual Specificity Phosphatase 1 MeSH
• JAK2 protein, human MeSH Browser
• Janus Kinase 2 MeSH
• STAT1 protein, human MeSH Browser
• STAT1 Transcription Factor MeSH