bromochloroacetic-acid and lactacystin

The specific pathogenesis of nodular goiter and the role of apoptosis in goitrogenesis are not known. We sought to examine the regulation of the TNF-related apoptosis-inducing ligand (TRAIL) and Fas ligand (FasL)-induced apoptosis pathways in primary thyroid cells from 17 patients with nodular goiter, using 10 normal thyroids as controls. Both goitrous and normal thyroid cells were resistant to recombinant human TRAIL and an agonist anti-Fas antibody under basal conditions. However, all normal thyrocytes could be sensitized by TNFalpha/IL-1beta or interferon gamma/IL-1beta to undergo apoptosis in response to TRAIL or FasL, respectively. In contrast, the majority of goiter-derived cells remained resistant to TRAIL (12 of 17 samples) or FasL (9 of 17 samples) after cytokine pretreatment; 14 of 17 goiter nodules were resistant to at least one death ligand. Goiter size was inversely correlated with the sensitivity to TRAIL-mediated apoptosis. The resistance of goiter cells to TRAIL did not appear to be due to transcriptional regulation or cell surface expression of death and decoy receptors. However, increased proteasome activity was found in a subset of goiter cells resistant to both death ligands, and proteasome inhibitors could sensitize these goiter cells to TRAIL-mediated apoptosis. In conclusion, goiter-derived thyroid cells are resistant to TRAIL and/or Fas-induced apoptosis in vitro, and this may represent a new aspect of aberrant growth regulation in goiter nodules. The increased proteasome activity associated with this resistance suggests that the proteasome may be an important regulator of apoptosis in nodular goiter.

Topics: Acetylcysteine; Apoptosis; Apoptosis Regulatory Proteins; Cell Survival; Cells, Cultured; Cysteine Proteinase Inhibitors; Epithelial Cells; fas Receptor; Goiter, Nodular; Humans; Immunoblotting; Interferon-gamma; Keratins; Membrane Glycoproteins; Recombinant Proteins; Reference Values; Thyroid Gland; Thyroidectomy; TNF-Related Apoptosis-Inducing Ligand; Tumor Necrosis Factor-alpha

Quinidine inhibits proliferation and promotes cellular differentiation in human breast tumor epithelial cells. Previously we showed quinidine arrested MCF-7 cells in G(1) phase of the cell cycle and led to a G(1) to G(0) transition followed by apoptotic cell death. The present experiments demonstrated that MCF-7, MCF-7ras, T47D, MDA-MB-231, and MDA-MB-435 cells transiently differentiate before undergoing apoptosis in response to quinidine. The cells accumulated lipid droplets, and the cytokeratin 18 cytoskeleton was reorganized. Hyperacetylated histone H4 appeared within 2 h of the addition of quinidine to the medium, and levels were maximal by 24 h. Quinidine-treated MCF-7 cells showed elevated p21(WAF1), hypophosphorylation and suppression of retinoblastoma protein, and down-regulation of cyclin D1, similar to the cell cycle response observed with cells induced to differentiate by histone deacetylase inhibitors, trichostatin A, and trapoxin. Quinidine did not show evidence for direct inhibition of histone deacetylase enzymatic activity in vitro. HDAC1 was undetectable in MCF-7 cells 30 min after addition of quinidine to the growth medium. The proteasome inhibitors MG-132 and lactacystin completely protected HDAC1 from the action of quinidine. We conclude that quinidine is a breast tumor cell differentiating agent that causes the loss of HDAC1 via a proteasomal sensitive mechanism.

Topics: Acetylation; Acetylcysteine; Animals; Anti-Bacterial Agents; Breast Neoplasms; Cell Cycle; Cell Differentiation; Cell Division; Chickens; Cyclin D1; Cyclin-Dependent Kinase Inhibitor p21; Cyclins; Cysteine Endopeptidases; Cysteine Proteinase Inhibitors; Cytoskeleton; Down-Regulation; Enzyme Inhibitors; Female; G1 Phase; Histone Deacetylase 1; Histone Deacetylase Inhibitors; Histone Deacetylases; Histones; Humans; Hydroxamic Acids; Immunoblotting; Keratins; Leupeptins; Multienzyme Complexes; Peptides; Phosphorylation; Proteasome Endopeptidase Complex; Quinidine; Retinoblastoma Protein; Time Factors; Tumor Cells, Cultured