Apoptosis is not observed following tumor necrosis factor alpha (TNF-α) and/or epidermal growth factor (EGF) treatment

Copyright information:Taken from "Tumor necrosis factor alpha and epidermal growth factor act additively to inhibit matrix gene expression by chondrocyte"Arthritis Research & Therapy 2004;7(1):R127-R138.Published online 29 Nov 2004PMCID:PMC1064891.Copyright © 2004 Klooster and Bernier., licensee BioMed Central Ltd. Confluent monolayers of chondrocytes were treated with vehicle, TNF-α (30 ng/ml), EGF (10 ng/ml) or TNF-α + EGF for 24 hours. Early stages of apoptosis were assayed by immunoblot with an antibody specific for intact and cleaved forms of poly(ADP ribose) polymerase (PARP). No cleavage of PARP (i.e. appearance of a band at 89 kDa) was detected following any of the treatments. Blot shown is representative of three independent experiments. Apoptosis-induced DNA strand breaks were examined by labeling (terminal deoxynucleotidyl transferase-mediated dUTP nick end-labeling [TUNEL]) and imaged using confocal microscopy. No TUNEL labeling was detected with any of the treatments. Cells treated with DNAse I to induce DNA breaks served as a positive control. Bar = 50 μm. Images are representative of three independent experiments.