Peroxiredoxin Genes are Not Induced in Myeloid Leukemia Cells Exposed to Ionizing Radiation

Abstract

Peroxiredoxins (Prx) comprise an extended family of small antioxidant proteins which conserve a thioredoxin-dependent catalytic function that can contribute to cell protection from reactive oxygen species (ROS). ROS generation is one of the deleterious intracellular effects of ionizing radiation, but the role of Prx during radiation treatment has not been extensively explored. Present experiments measure effects of ionizing radiation on expression of human Prx types I (PAGA), II (NKEF-B) and IV (AOE372) in human myeloid leukemia cells (K562). Prx gene transcription was analyzed by amplifying with RT-PCR cDNAs complementary to each Prx-specific coding sequence and by identifying the derived products with Southern blotting procedure. Transcripts of GAPDH were used as the endogenous standard for semi-quantitative comparisons. No consistent increase in Prx gene expression was detected at time intervals up to 72 h after gamma radiation doses that caused cell cycle arrest and nuclear damage (maximum 20 Gy). Immunoblots also were consistent with a prolonged expression or stability of the Prx I/II proteins. Similarly, a cytotoxic concentration of the oxidant hemin, which stimulates rapid hemoglobinization of K562 cells, caused no induction of Prx gene expression. Our results indicate a high Prx stability in human radio-resistant leukemia cells.

Expression and Secretion of CXCL8 (IL-8), Release of Tryptase and Transcription of Histidine Decarboxylase mRNA by Anti-IgE-Activated Human Umbilical Cord Blood-Derived Cultured Mast Cells

“…Severe acute allergic diseases can be induced by different triggers which induce inflammation [41][42][43][44][45][46] . Inflammatory cells such as activated PMN identified in bronchoalveolar lavage in allergic patients are associated with increased levels of IL-8 and proinflammatory mediators [16,27,30,45,47,48] .…”

Regulation of Cancer Cell Responsiveness to Ionizing Radiation Treatment by Cyclic AMP Response Element Binding Nuclear Transcription Factor

“…Interestingly, 6 Gy is the suboptimal dose delivered in RT protocols for the treatment of human hematological tumors, whereas it induces evident damage in many cancer cell lines (58). As previously demonstrated, K562 are radio-resistant human leukemia cells that express a high peroxiredoxins (Prx) stability (60). Prx are an extended family of small antioxidant proteins that conserve a thioredoxin-dependent catalytic function contributing to cell protection from reactive oxygen species, which are one of the deleterious intracellular effectors of IR damage.…”

Cyclic nucleotide response element binding (CREB) protein activation is involved in K562 erythroleukemia cells differentiation

“…In this study, we investigated the possible role of CREB in the early (1 and 3 h) and late (4 and 6 days) events related to hemin-induced differentiation of K562 cells. The choice of K562 myeloid leukemia cells for present experiments was based on susceptibility to erythroid differentiation by hemin, an agent with redox potential as reported in the literature [Chenais et al, 2000;Di Pietro et al, 2006]. A specific p38 MAP kinase inhibitor, SB203580, was used to evaluate the possible involvement of this enzymatic activity in the control of CREB signaling pathway leading to erythroid differentiation of human K562 neoplastic cells [McCubrey et al, 2000;Pearson et al, 2001;Stork and Schmitt, 2002].…”