4-hydroxy-2-nonenal and Leukemia--Erythroblastic--Acute

4-hydroxy-trans-2-nonenal (HNE) is one of the most abundant and toxic lipid aldehydes formed during lipid peroxidation by reactive oxygen species. We have investigated the genotoxic effects of HNE and its regulation by cellular glutathione (GSH) levels in human erythroleukemia (K562) cells. Incubation of K562 cells with HNE (5-10 microM) significantly elicited a 3- to 5-fold increased DNA damage in a time- and dose-dependent manner as measured by comet assay. Depletion of GSH in cells by L-buthionine-[S,R]-sulfoximine (BSO) significantly increased HNE-induced DNA damage, whereas supplementation of GSH by incubating the cells with GSH-ethyl ester significantly decreased HNE-induced genotoxicity. Further, overexpression of mGSTA4-4, a HNE-detoxifying GST isozyme, significantly prevented HNE-induced DNA damage in cells, and ablation of GSTA4-4 and aldose reductase with respective siRNAs further augmented HNE-induced DNA damage. These results suggest that the genotoxicity of HNE is highly dependent on cellular GSH/GST/AR levels and favorable modulation of the aldehyde detoxification system may help in controlling the oxidative stress-induced complications.

Topics: Aldehyde Reductase; Aldehydes; Comet Assay; Cysteine Proteinase Inhibitors; DNA Damage; Dose-Response Relationship, Drug; Glutathione; Glutathione Transferase; Humans; Image Processing, Computer-Assisted; K562 Cells; Leukemia, Erythroblastic, Acute; Mutagens; Oxidative Stress; RNA, Small Interfering; Time Factors; Transfection

4-Hydroxynonenal (HNE) is one of the major end products of lipid peroxidation. Here we show that the exposure of murine erythroleukemia (MEL) cells to 1 microM HNE, for 10.5 h over 2 days, induces a differentiation comparable with that observed in cells exposed to DMSO for the whole experiment (7 days). The exposure of MEL cells for the same length of time demonstrates a higher degree of differentiation in HNE-treated than in DMSO-treated MEL cells. The protooncogene c-myc is down-modulated early, in HNE-induced MEL cells as well as in DMSO-treated cells. However, ornithine decarboxylase gene expression first increases and then decreases, during the lowering of the proliferation rate. These findings indicate that HNE, at a concentration physiologically found in many normal tissues and in the plasma, induces MEL cell differentiation by modulation of specific gene expression.

Topics: Aldehydes; Animals; Cell Differentiation; Cell Division; Gene Expression; Genes, myc; Growth Inhibitors; Leukemia, Erythroblastic, Acute; Mice; Ornithine Decarboxylase; Tumor Cells, Cultured

4-Hydroxynonenal (HNE) is a highly reactive aldehyde, produced by cellular lipid peroxidation, able to inhibit proliferation and to induce differentiation in MEL cells at concentrations similar to those detected in several normal tissues. Inducer-mediated differentiation of murine erythroleukemia (MEL) cells is a multiple step process characterized by modulation of several genes as well as by a transient increase in the amount of membrane-associated protein kinase C (PKC) activity. Here we demonstrate that a rapid translocation of PKC activity from cytosol to the membranes occurs during the differentiation induced by HNE. When PKC is completely translocated by phorbol-12-myristate-13-acetate (TPA), the degree of HNE-induced MEL cells differentiation is highly decreased. However, if TPA is washed out from the culture medium before the exposition to the aldehyde, HNE gradually resumes its differentiative ability. The incubation of cells with a selective inhibitor of PKC activity, bisindolylmaleimide GF 109203X, partially prevents the HNE-induced differentiation in MEL cells. In conclusion, our results demonstrate that HNE-induced MEL cell differentiation is preceded by a rapid translocation of PKC activity, and that the inhibition of this phenomenon prevents the onset of terminal differentiation.

Topics: Aldehydes; Animals; Biological Transport, Active; Cell Differentiation; Cell Division; Dimethyl Sulfoxide; Enzyme Inhibitors; Hemoglobins; Indoles; Leukemia, Erythroblastic, Acute; Maleimides; Mice; Protein Kinase C; Tetradecanoylphorbol Acetate; Tumor Cells, Cultured

Several studies point to the existence of an inverse correlation between cellular lipid peroxidation and both cell proliferation and neoplastic transformation. Here, we show that 4-hydroxynonenal (HNE) concentrations close to the level found in normal cells (in the range of 1 and 3 microM) can specifically induce changes in the expression of c-myc and gamma-globin mRNA in K562 cells, without inducing any toxic effects or affecting cell viability. Since we have determined that K562 cells have undetectable levels of endogenous lipid peroxidation, all these effects can be assigned to the exogenous HNE treatment. After a 1-h treatment with 1 microM HNE, c-myc mRNA levels decrease transiently during the first 4 h, rebounding later to higher levels, and normalizing to basal expression after 4 days. Run-on experiments show a transient transcriptional block 20 min after HNE treatment and subsequent posttranscriptional regulation. According to S1 mapping, mRNA changes are exerted on c-myc transcripts initiated from both the principal constitutive start sites (P1 and P2). gamma-Globin mRNA levels concomitantly increase 3- to 4-fold, but no significant changes of housekeeping gene expression are observed. On the basis of these results it appears that the restoration in human erythroleukemic K562 cells of HNE concentrations closer to the level in normal cells can modulate the expression of specific genes.

Topics: Aldehydes; Gene Expression; Genes, myc; Globins; Humans; In Vitro Techniques; Leukemia, Erythroblastic, Acute; Lipid Peroxides; RNA, Messenger; RNA, Neoplasm; Tumor Cells, Cultured