NF-kappaB-dependency and consequent regulation of IL-8 in echinomycin-induced apoptosis of HT-29 colon cancer cells.
The present study was to see whether echinomycin-induced apoptosis would be NF-kappaB-dependent and if so, whether echinomycin would activate or inhibit NF-kappaB as well as resultant chemokine IL-8 expression. In HT-29 cells echinomycin activated NF-kappaB in time-dependent manner. EMSA in the presence of antibodies specific for p50 and p65 subunits indicated that echinomycin-induces the translocation of p50-p65 heterodimeric subunits of NF-kappaB. Levels of IkappaB were detected at initial echinomycin treatment and thereafter decreased, faintly seen after a 6h treatment. In contrast p-IkappaB levels were clearly detected throughout 6-24h of echinomycin treatment, albeit initially fainted. To clarify the role of NF-kappaB on IL-8 expression in echinomycin-mediated apoptosis of HT-29 cells, ELISA plus RT-PCR clearly showed that IL-8 production is inducible by echinomycin treatment. Using a specific inhibitor, IL-8 regulation at echinomycin treatment in HT-29 cells occurred via both caspase-3 and NF-kappaB-dependent signal pathway. To confirm whether two different pathways (NF-kappaB and caspase) would be coupled, only NF-kappaB inhibitor (PDTC) and caspase-3 specific inhibitor (Z-DEVD-FMK) together significantly attenuated echinomycin-initiated apoptosis of HT-29 cells, pretreatment of HT-29 cells with PDTC rarely affected echinomycin-induced caspase-3 activation. So echinomycin-induced apoptosis in HT-29 cells occurs via NF-kappaB activation independent of caspase-3 activation modulating the resultant-linked key chemokine IL-8 expression and echinomycin-induced apoptosis is NF-kappaB-dependant and directly related to NF-kappaB activation, consequently regulating IL-8 expression.
Park
Ju Youn
JY
Department of Microbiology, Yonsei University Wonju College of Medicine, Wonju 220-701, Republic of Korea.
Chang
Jae-Ho
JH
Bae
Keum Seok
KS
Lee
Kyoung Ho
KH
Choi
Sun Ju
SJ
Park
Joo Young
JY
Ryang
Yong Suk
YS
Kim
Soo-Ki
SK
D000903:Antibiotics, Antineoplastic / Q000494:pharmacology*; D017209:Apoptosis / Q000187:drug effects*; D053148:Caspase 3 / Q000378:metabolism; D061945:Caspase Inhibitors; D045744:Cell Line, Tumor; D003110:Colonic Neoplasms / Q000378:metabolism*; D015853:Cysteine Proteinase Inhibitors / Q000378:metabolism; D004448:Echinomycin / Q000494:pharmacology*; D004789:Enzyme Activation; D006801:Humans; D051550:I-kappa B Kinase / Q000235:genetics / Q000378:metabolism; D016209:Interleukin-8 / Q000235:genetics / Q000378:metabolism*; D007976:Leupeptins / Q000378:metabolism; D016328:NF-kappa B / Q000235:genetics / Q000378:metabolism*; D021122:Protein Subunits / Q000235:genetics / Q000378:metabolism; D015398:Signal Transduction / Q000187:drug effects / Q000502:physiology
D000903:Antibiotics, Antineoplastic; D061945:Caspase Inhibitors; D015853:Cysteine Proteinase Inhibitors; D016209:Interleukin-8; D007976:Leupeptins; D016328:NF-kappa B; D021122:Protein Subunits; D004448:Echinomycin; D051550:I-kappa B Kinase; D053148:Caspase 3; C072553:benzyloxycarbonylleucyl-leucyl-leucine aldehyde