Correlation of oxidant-induced acute ATP depletion with delayed cell death in human neuroblastoma cells

We correlated theadenine nucleotide (AN) levels and energy charge (EC) at the end of atransient oxidative exposure to the delayed death of neuronal cells.When wild-type (WT) or Bcl-2-overexpressing (BCL-2) human neuroblastomacells (Paju) were exposed to 250 µM H₂O₂for 60 min, the EC of WT cells was unchanged, but that of BCL-2 cellsdecreased from 0.91 ± 0.03 to 0.67 ± 0.02. Depletion of ANs wassignificantly greater in BCL-2 (66.7 ± 2%) than in WT (38.8 ± 2%) cells. Proliferation of both lines decreased, averaging 63 ± 17% of control by 48 h. Exposure to 5 mMH₂O₂caused no further change in ANs in BCL-2 cells but in WT cellsdecreased the EC to 0.45 ± 0.08 and depleted ANs to 41 ± 9% ofcontrol; after 24 h, WT cells became pyknotic and showed DNAfragmentation but no chromatin condensation, whereas BCL-2 cells diedby delayed necrosis. After 10 mMH₂O₂,EC dropped to 0.15 ± 0.1, and both lines were acutely killed. TheEC after an oxidative insult correlated well with further growth ofboth cell lines. A significant decline in EC led to delayed death.Bcl-2 did not protect against the fall in EC or AN depletion, but,although survival was not improved, the mechanism of death appeared tobe different.

     

Characterization of Leukocyte Formin FMNL1 Expression in Human Tissues

Formins are cytoskeleton regulating proteins characterized by a common FH2 structural domain. As key players in the assembly of actin filaments, formins direct dynamic cytoskeletal processes that influence cell shape, movement and adhesion. The large number of formin genes, fifteen in the human, suggests distinct tasks and expression patterns for individual family members, in addition to overlapping functions. Several formins have been associated with invasive cell properties in experimental models, linking them to cancer biology. One example is FMNL1, which is considered to be a leukocyte formin and is known to be overexpressed in lymphomas. Studies on FMNL1 and many other formins have been hampered by a lack of research tools, especially antibodies suitable for staining paraffin-embedded formalin-fixed tissues. Here we characterize, using bioinformatics tools and a validated antibody, the expression pattern of FMNL1 in human tissues and study its subcellular distribution. Our results indicate that FMNL1 expression is not restricted to hematopoietic tissues and that neoexpression of FMNL1 can be seen in epithelial cancer.