Regulation of IGFBP6 gene and protein is mediated by the inverse expression and function of c-jun N-terminal kinase (JNK) and NFκB in a model of oral tumor cells
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The aim of this study is to identify potential gene and protein targets when nuclear factor kappa B (NFκB) and c-jun N-terminal kinase (JNK) were inversely expressed in oral tumors. To determine which genes were regulated synergistically by the inverse expression of NFκB and JNK, a pathway specific microarray analysis was performed. While either inhibition of NFκB or activation of JNK alone was unable to affect the IGFBP6 gene expression in microarray analysis, concomitant increase in JNK activation in the presence of NFκB inhibition increased the expression of this gene significantly. Synergistic increase in IGFBP6 gene expression was also confirmed by RT-PCR and Northern blot analysis of transfected cells. Accordingly, the levels of IGFBP6 protein secretion rose synergistically when JNK was over-expressed in NFκB knock down cells. In addition, increased expression of JNK in the absence of NFκB resulted in a significant induction of cell death in oral tumors when either left untreated or treated with TNF-α and TPA. Moreover, when JNK was inhibited by dominant negative JNK (APF), a significant decrease in cell death could be observed in TNF-α and TPA treated NFκB knock down oral tumors. Therefore, increased induction of IGFBP6 gene or protein expression in oral tumors could be regarded as a potential predictive marker of tumor sensitivity and could be used for prognostic purposes, since a significant correlation could be observed between increased induction of apoptotic cell death and elevated levels of IGFBP6 in these tumors.
KeywordsApoptosis NFκB IκB TNF-α JNK
The authors acknowledge the excellent technical assistance of Pedram Zarabian and Danielle Farzam. This work was supported by RO1-DE12880 from NIDCR-NIH.
- 27.Liu Y, Gorospe M, Yang C, Holbrook NJ (1995) Role of mitogen-activated protein kinase phosphatase during the cellular response to genotoxic stress. Inhibition of c-Jun N-terminal kinase activity and AP-1-dependent gene activation. J Biol Chem 270:8377–8380. doi: 10.1074/jbc.270.15.8377 PubMedCrossRefGoogle Scholar
- 30.Chen YR, Wang X, Templeton D, Davis RJ, Tan TH (1996) The role of c-Jun N-terminal kinase (JNK) in apoptosis induced by ultraviolet C and gamma radiation. Duration of JNK activation may determine cell death and proliferation. J Biol Chem 271:31929–31936. doi: 10.1074/jbc.271.50.31929 PubMedCrossRefGoogle Scholar
- 37.Castrillo A, Traves PG, Martin-Sanz P, Parkinson S, Parker PJ, Bosca L (2003) Potentiation of protein kinase C zeta activity by 15-deoxy-delta(12, 14)-prostaglandin J(2) induces an imbalance between mitogen-activated protein kinases and NF-kappa B that promotes apoptosis in macrophages. Mol Cell Biol 23:1196–1208. doi: 10.1128/MCB.23.4.1196-1208.2003 PubMedCrossRefGoogle Scholar
- 44.Jewett A, Wang MY, Teruel A, Poupak Z, Bostanian Z, Park NH (2003) Cytokine dependent inverse regulation of CD54 (ICAM1) and major histocompatibility complex class I antigens by nuclear factor kappaB in HEp2 tumor cell line: effect on the function of natural killer cells. Hum Immunol 64:505–520. doi: 10.1016/S0198-8859(03)00039-9 PubMedCrossRefGoogle Scholar
- 46.Maniatis T, Fritsch EF, Sambrook J (1982) Molecular cloning: a laboratory manual. Cold Spring Harbor University Press, Cold Spring HarborGoogle Scholar
- 53.Bach LA, Rechler MM (1996) Measurement of insulin-like growth factor (IGF)-II binding to purified IGF binding proteins 1–6: comparison of charcoal adsorption and high performance size exclusion chromatography. Biochim Biophys Acta 1313:79–88. doi: 10.1016/0167-4889(96)00053-5 PubMedCrossRefGoogle Scholar
- 56.Kato M, Ishizaki A, Hellman U et al (1995) A human keratinocyte cell line produces two autocrine growth inhibitors, transforming growth factor-beta and insulin-like growth factor binding protein-6, in a calcium- and cell density-dependent manner. J Biol Chem 270:12373–12379. doi: 10.1074/jbc.270.21.12373 PubMedCrossRefGoogle Scholar