Blocking of NF-kappaB activation enhances the tumor necrosis factor alpha-induced apoptosis of a human gastric cancer cell line.
The transcription factor NF-kappaB is constitutively activated in many human cancers and induces the expression of multiple genes, including those of anti-apoptotic proteins. This study investigated the mechanism by which human gastric cancer cells (MKN45) are resistant to apoptosis induced by tumor necrosis factor alpha (TNF-alpha). Confluent monolayers of MKN45 cells were either pretreated or not for 60 min with PSI, a peptide aldehyde known to specifically inhibit the chymotrypsin-like activity of 26S proteasome. Cells were subsequently stimulated with recombinant human TNF-alpha, and cell viabilities were determined by the WST-1 assay. Apoptosis was confirmed by fluorescence microscopy after staining with Hoechst 33342, and DNA fragmentation was determined by a DNA fragmentation detection kit. A 24-h incubation with either TNF-alpha or PSI alone did not affect cell viabilities; however, pretreatment with PSI significantly enhanced the level of apoptosis induced by TNF-alpha. Therefore, this study suggests the possibility that blocking of NF-kappaB activity renders gastric cancer cells susceptible to the apoptosis induced by TNF-alpha.
Ueda
Miho
M
First Department of Medicine, Kyoto Prefectural University of Medicine, Kawaramachi-Hirokoji, Kamigyo-ku, Kyoto 602-8566, Japan.
Kokura
Satoshi
S
Imamoto
Eiko
E
Naito
Yuji
Y
Handa
Osamu
O
Takagi
Tomohisa
T
Yoshida
Norimasa
N
Yoshikawa
Toshikazu
T
D017209:Apoptosis; D002470:Cell Survival; D003546:Cysteine Endopeptidases / Q000378:metabolism; D053938:DNA Fragmentation; D004305:Dose-Response Relationship, Drug; D006801:Humans; D008856:Microscopy, Fluorescence; D009097:Multienzyme Complexes / Q000378:metabolism; D016328:NF-kappa B / Q000037:antagonists & inhibitors* / Q000378:metabolism*; D046988:Proteasome Endopeptidase Complex; D011994:Recombinant Proteins / Q000494:pharmacology; D013274:Stomach Neoplasms / Q000378:metabolism*; D013997:Time Factors; D014407:Tumor Cells, Cultured; D014409:Tumor Necrosis Factor-alpha / Q000378:metabolism*; D025801:Ubiquitin / Q000378:metabolism
D009097:Multienzyme Complexes; D016328:NF-kappa B; D011994:Recombinant Proteins; D014409:Tumor Necrosis Factor-alpha; D025801:Ubiquitin; D003546:Cysteine Endopeptidases; D046988:Proteasome Endopeptidase Complex