TNF increases camptothecin-induced apoptosis by inhibition of NF-kappaB.
rHuTNF potentiates CPT-cytotoxicity in human ovarian A2780 cells. In this study, we examined the role of NF-kappaB in this potentiation. A pulse-labelled DNA study indicated that the combination CPT+TNF had little effect on the rate of DNA elongation at 6 h after drug removal, whereas CPT alone produced a complete inhibition for at least 6 h after drug removal. Flow cytometry analyses showed that CPT+TNF arrested cells in the G2-M phase, whereas CPT blocked cells in S phase. Looking at the persistence of the NF-kappaB complexes in cells, it appeared that they were still present at 24 h in TNF-treated cells. In contrast, in CPT-treated cells they persisted for 6 h. In CPT+TNF-treated cells, the NF-kappaB complexes disappeared quickly and became undetectable at 6 h. The induction of apoptosis was detected only in the CPT+TNF treated cells (using flow cytometry, a filter binding assay and ApopTag staining). These findings show that TNF, in combination with CPT, reduces the time that NF-kappaB complexes persist in cells likely resulting in the induction of apoptosis.
Valente
P
P
Medical Oncology, University of, Genova, Italy.
Arzani
D
D
Cesario
A
A
Margaritora
S
S
Carbone
E
E
Russo
P
P
D000972:Antineoplastic Agents, Phytogenic / Q000627:therapeutic use*; D017209:Apoptosis / Q000187:drug effects*; D002166:Camptothecin / Q000627:therapeutic use*; D004247:DNA / Q000096:biosynthesis; D005260:Female; D005434:Flow Cytometry; D006801:Humans; D016328:NF-kappa B / Q000037:antagonists & inhibitors*; D010051:Ovarian Neoplasms / Q000188:drug therapy* / Q000473:pathology; D014407:Tumor Cells, Cultured; D014409:Tumor Necrosis Factor-alpha / Q000494:pharmacology*
D000972:Antineoplastic Agents, Phytogenic; D016328:NF-kappa B; D014409:Tumor Necrosis Factor-alpha; D004247:DNA; D002166:Camptothecin