Proteasome Inhibition Increases Recruitment of IκB Kinase β (IKKβ), S536P-p65, and Transcription Factor EGR1 to Interleukin-8 (IL-8) Promoter, Resulting in Increased IL-8 Production in Ovarian Cancer Cells

Abstract

Background: IL-8 promotes angiogenesis and metastasis in ovarian cancer. Results: Proteasome inhibition induces specific recruitment of IKK␤, EGR-1, and S536P-p65 to the IL-8 promoter. Conclusion:The increased IKK␤, EGR-1, and S536P-p65 recruitment results in the increased IL-8 expression and release in ovarian cancer cells. Significance: The BZ-increased IL-8 release may be responsible for the BZ-limited effectiveness in ovarian cancer treatment.

Histone Deacetylase (HDAC) Inhibition Induces IκB Kinase (IKK)-dependent Interleukin-8/CXCL8 Expression in Ovarian Cancer Cells

“…As we have shown previously (12), both p65 and p50 are localized predominantly in the nucleus in OC cells (Fig. 5A).…”

“…Cells were cultured (5 ϫ 10 5 cells/ml) in 6-well plates in RPMI 1640 medium (Invitrogen) supplemented with 10% heat-inactivated FBS (Invitrogen) and antibiotics at 37°C with 5% CO 2 as described previously (12,13). For in vitro experiments, vorinostat, romidepsin, apicidin, Bay 117085, and SB 203580 were dissolved in DMSO, and an equivalent DMSO volume was used as a solvent control.…”

“…The primers used for quantification of human IL-8/CXCL8, TNF␣, IL-6, CXCL5, TGF␤1, cIAP-1, Bcl-2, p65, p50, IB␣, CXCR-1, CXCR2, IKK␣, IKK␤, IKK⑀, and actin mRNA were purchased from SA Biosciences (Frederick, MD). The mRNA values are expressed as a percentage of untreated (UT) samples, which were arbitrarily set as 100% (12).…”

“…ELISA-Human IL-8/CXCL8, TNF␣, IL-6, and TGF␤1 release was measured by commercially available ELISA kits (R&D Systems) as described previously (12,13).…”

“…Although the proteasomal degradation of IB␣, resulting in the nuclear accumulation of NFB subunits, represents a general step in NFB activation, the specificity and duration of NFB-regulated responses are mediated by the protein composition of NFB complexes and their posttranslational modifications (8 -11). Recent studies from our laboratory have demonstrated that IKK is specifically recruited to the NFB-binding site in the IL-8/CXCL8 promoter, resulting in increased IL-8/CXCL8 transcription in EOC cells (12)(13)(14).…”