Mechanisms of constitutive NF-kappaB activation in human prostate cancer cells.
BACKGROUND
Activation of the NF-kappaB transcription factor has been previously demonstrated in two androgen receptor negative prostate cancer cell lines. We wished to extend this work to additional prostate cancer cells and to characterize the mechanisms responsible for constitutive NF-kappaB activation.


METHODS
Electrophoretic mobility shift assays were performed to measure NF-kappaB DNA-binding activity in prostate cancer cell lines, and immunohistochemistry was performed to detect nuclear localization of NF-kappaB in prostate cancer tissues. Western blot analysis was used to study the status of IkappaBalpha. Transient transfection assays were employed to characterize the contributions of IkappaB kinase (IKK), MAPK kinase kinases (MAPKKKs), androgen receptor (AR), and tyrosine phosphorylation to the constitutive activation of NF-kappaB in the prostate cancer cell lines.


RESULTS
Constitutive NF-kappaB activity was observed in AR-negative cell lines as well as in the prostate cancer patient samples, but was not present in AR positive cells. A "super-repressor" IkappaBalpha, as well as dominant negative forms of IKKbeta and NF-kappaB-inducing kinase (NIK), and tyrosine kinase inhibition were able to suppress NF-kappaB activity in the cells with constitutive activation.


CONCLUSIONS
The constitutive activation of NF-kappaB observed in prostate cancer cells is likely due to a signal transduction pathway involving tyrosine kinases, NIK, and IKK activation.
Center for Advanced Biotechnology and Medicine, Piscataway, New Jersey 08854, USA.
Junghan
J
Suh
Faribourz
F
Payvandi
Leonard C
LC
Edelstein
Peter S
PS
Amenta
Wei-Xing
WX
Zong
Céline
C
Gélinas
Arnold B
AB
Rabson
D004268:DNA-Binding Proteins / Q000378:metabolism; D006801:Humans; D051550:I-kappa B Kinase; D020672:I-kappa B Proteins; D008297:Male; D000072000:NF-KappaB Inhibitor alpha; D016328:NF-kappa B / Q000502:physiology*; D011471:Prostatic Neoplasms / Q000378:metabolism* / Q000473:pathology; D017346:Protein Serine-Threonine Kinases / Q000378:metabolism; D011505:Protein-Tyrosine Kinases / Q000378:metabolism; D014407:Tumor Cells, Cultured; D000097782:NF-kappaB-Inducing Kinase
D004268:DNA-Binding Proteins; D051550:I-kappa B Kinase; D020672:I-kappa B Proteins; D000072000:NF-KappaB Inhibitor alpha; D016328:NF-kappa B; D017346:Protein Serine-Threonine Kinases; D011505:Protein-Tyrosine Kinases; D000097782:NF-kappaB-Inducing Kinase; C000606204:NFKBIA protein, human; C496559:CHUK protein, human; C496560:IKBKB protein, human; C496565:IKBKE protein, human