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An essential role for nuclear factor kappa B in preventing TNF-alpha-induced cell death in prostate cancer cells
M Sumitomo1, M Tachibana, J Nakashima
1Department of Urology, National Defense Medical College, Tokorozawa, Saitama, Japan.
Purpose:
Although tumor necrosis factor-alpha (TNF-alpha) induces a strong cytotoxic effect on cell growth, many authors have reported that various cancer cells are resistant to TNF-alpha and the basis for this sensitivity or resistance to TNF-alpha remains to be elucidated. Since nuclear factor kappa B (NF-kappaB) activation has recently been reported to inhibit TNF-alpha-induced cell death, we studied whether NF-kappaB also assumes a protective role in TNF-alpha-induced cell death in prostate cancer cells.
Materials And Methods:
We used two human prostate cancer cell lines of DU145 and PC-3. We prepared two different NF-kappaB inhibitors, pyrrolidine dithiocarbamate (PDTC) and NF-kappaB decoy. NF-kappaB DNA binding activity was detected by electrophoretic mobility shift assay (EMSA). Cell survivals were measured by MTT assay. Induction of apoptosis was detected by nuclear staining and measured by fragmented DNA ELISA.
Results:
EMSA showed that NF-kappaB inhibitors continuously inhibited TNF-alpha-induced NF-kappaB activation. Cell growth was not inhibited by either TNF-alpha (50 ng./ml. or less) or NF-kappaB inhibitors. However, both PCA cells treated with TNF-alpha (20 ng./ml.) plus NF-kappaB inhibitors showed significant growth inhibition compared with controls (p<0.05). Nuclei of PCA cells appeared severely fragmented by this combination therapy. Furthermore, the levels of DNA fragmentation were significantly elevated in PCA cells treated with TNF-alpha (20 ng./ml.) plus NF-kappaB inhibitors compared with controls (p<0.05).
Conclusions:
NF-kappaB activation is suggested to produce the resistance of DU145 and PC-3 to TNF-alpha and that the combination of TNF-alpha and NF-kappaB inhibitors could be constituted an effective therapy to TNF-alpha-resistant human prostate cancer cells.
Insights
Nuclear factor kappa B (NF-kappaB) activation confers resistance to tumor necrosis factor-alpha (TNF-alpha) in prostate cancer cells. Combining TNF-alpha with NF-kappaB inhibitors effectively inhibits cancer cell growth and induces apoptosis.
Area of Science:
- Oncology
- Molecular Biology
- Cancer Research
Background:
- Tumor necrosis factor-alpha (TNF-alpha) exhibits potent cytotoxic effects, yet many cancer cells display resistance.
- The mechanisms underlying TNF-alpha sensitivity or resistance remain incompletely understood.
- Nuclear factor kappa B (NF-kappaB) activation has been implicated in inhibiting TNF-alpha-induced cell death.
Purpose of the Study:
- To investigate the role of NF-kappaB in TNF-alpha-induced cell death in prostate cancer.
- To determine if NF-kappaB activation contributes to resistance against TNF-alpha therapy in prostate cancer cells.
Main Methods:
- Utilized DU145 and PC-3 human prostate cancer cell lines.
- Employed NF-kappaB inhibitors: pyrrolidine dithiocarbamate (PDTC) and NF-kappaB decoy.
- Assessed NF-kappaB DNA binding activity via electrophoretic mobility shift assay (EMSA).
- Measured cell survival using MTT assay and apoptosis induction via nuclear staining and fragmented DNA ELISA.
Main Results:
- NF-kappaB inhibitors effectively blocked TNF-alpha-induced NF-kappaB activation.
- Prostate cancer cells treated with TNF-alpha and NF-kappaB inhibitors exhibited significant growth inhibition and apoptosis.
- Combination therapy led to severe nuclear fragmentation and elevated DNA fragmentation levels.
Conclusions:
- NF-kappaB activation appears to mediate resistance in DU145 and PC-3 prostate cancer cells to TNF-alpha.
- Combining TNF-alpha with NF-kappaB inhibitors presents a promising therapeutic strategy for TNF-alpha-resistant prostate cancers.