The angiogenic factor interleukin 8 is induced in non-small cell lung cancer/pulmonary fibroblast cocultures.

The interactions between tumor cells and surrounding stromal elements may promote the release of angiogenic factors. Although interleukin 8 (IL-8) is a major angiogenic factor in non-small cell lung cancer (NSCLC), the stromal contribution to IL-8 expression in primary NSCLC remains to be defined. To elucidate the role of stromal elements in NSCLC IL-8 production, normal pulmonary fibroblasts were cocultured with six representative NSCLC lines in direct and transwell assays. IL-8 transcripts and protein were consistently induced in fibroblasts and a subset of NSCLCs as a consequence of tumor/stromal coculture. In these cocultures, IL-8 was induced by IL-1alpha and an additional, as yet unidentified, soluble factor. These data underscore the importance of tumor/stromal interaction in the production of angiogenic peptides such as IL-8 in NSCLC.

Chromium(VI) inhibits the transcriptional activity of nuclear factor-kappaB by decreasing the interaction of p65 with cAMP-responsive element-binding protein-binding protein.

Chromium(VI) regulation of gene expression has been attributed to the generation of reactive chromium and oxygen species, DNA damage, and alterations in mRNA stability. However, the effects of Cr(VI) on signal transduction leading to gene expression are not resolved. Therefore, this study investigated the effects of Cr(VI) on basal and tumor necrosis factor-alpha (TNF-alpha)-induced transcriptional competence of nuclear factor-kappaB (NF-kappaB) in A549 human lung carcinoma cells. Pretreatment of A549 cells with nontoxic levels of Cr(VI) inhibited TNF-alpha-stimulated expression of the endogenous gene for interleukin-8 and of an NF-kappaB-driven luciferase gene construct, but not expression of urokinase, a gene with a more complex promoter. Chromium did not inhibit TNF-alpha-stimulated IkappaBalpha degradation or translocation of NF-kappaB-binding proteins to the nucleus. However, Cr(VI) pretreatments prevented TNF-alpha-stimulated interactions between the p65 subunit of NF-kappaB and the transcriptional cofactor cAMP-responsive element-binding protein-binding protein (CBP). This inhibition was not the result of an effect of chromium on the protein kinase A catalytic activity required for p65/CBP interactions. In contrast, Cr(VI) caused concentration-dependent increases in c-Jun/CBP interactions. These data indicate that nontoxic levels of hexavalent chromium selectively inhibit NF-kappaB transcriptional competence by inhibiting interactions with coactivators of transcription rather than DNA binding.