Inducible gene expression: V.1: Environmental stresses and nutrient

Bostonxii, 284 p.; 25 c

Inducible gene expression : V.2: Hormonal signals

Bostonxii, 284 p.; 25 c

The emerging role of EpCAM in cancer and stem cell signaling.

Initially discovered as a dominant antigen on colon carcinomas, the epithelial cell adhesion molecule (EpCAM) was considered a mere cell adhesion molecule and reliable surface-binding site for therapeutic antibodies. Recent findings can better explain the relevance of EpCAM's high-level expression on human cancers and cancer propagating cells, and its negative prognostic potential for survival of patients with certain cancers. EpCAM has oncogenic potential and is activated by release of its intracellular domain, which can signal into the cell nucleus by engagement of elements of the wnt pathway

Purification, Reconstitution, and IkappaB Association of the c-Rel-p65 (RelA) Complex, a Strong Activator of Transcription

HeLa cells contain a DNA-binding activity which associates with a kappa B-like DNA element, termed Rel-related protein-binding element (RRBE), localized upstream of the human urokinase promoter. We have purified this activity from the HeLa cell cytosol and have shown that it represents a performed heteromeric complex between p65 (RelA) and c-Rel. Coexpression of c-Rel and p65 (RelA) by in vitro translation formed a DNA-binding complex indistinguishable from purified cellular c-Rel-p65 (RelA) in mobility shift assays. The c-Rel-p65 (RelA) complex was also formed in COS7 cells upon coexpression of c-Rel and p65 (RelA) cDNAs. Cotransfection experiments with COS7 cells, using expression plasmids encoding p50, p65 (RelA), or c-Rel and reporter constructs containing a trimerized RRBE, revealed that c-Rel-p65 (RelA) is a potent activator of the RRBE, giving rise to transcriptional activity higher than that observed with NF-kappa B (p50-p65). In the cytosol, the c-Rel-p65 (RelA) complex existed in a latent, non-DNA-binding form but could be activated by detergent treatment, suggesting that it was associated with an I kappa B protein. Recombinant I kappa B-alpha inhibited the DNA-binding activity of c-Rel-p65 (RelA) via association with either c-Rel or p65 (RelA). Finally, NF-kappa B and c-Rel-p65 (RelA) complexes were found to be differentially expressed and regulated in different cells. The two complexes were present in equimolar amounts in HeLa cells and K562 cells. Stimulation with tetradecanoyl phorbol acetate (TPA) resulted in the nuclear translocation of both NF-kappa B and c-Rel-p65 (RelA) in HeLa cells and of NF-kappa B in HepG2 cells but had no effect on either complex in K562 cells. In addition, TPA stimulation of HepG2 cells induced the expression of a cytosolic latent c-Rel-p65 (RelA) complex which, however, was not translocated to the nucleus. In conclusion, our findings show that c-Rel-p65 (RelA) is an inducible and very potent transcriptional activator which is differentially activated in a cell-type-specific manner

Cloning of the murine RelA (p65 NF-kB) gene and comparison to the human gene reveals a distinct first intron

Linker RA, Baeuerle PA, Kaltschmidt C. Cloning of the murine RelA (p65 NF-kB) gene and comparison to the human gene reveals a distinct first intron. Gene. 1996;176:119-124

Antitumor activity of a dual cytokine/single-chain antibody fusion protein for simultaneous delivery of GM-CSF and IL-2 to Ep-CAM expressing tumor cells

Cytokine targeting to tumor-associated antigens via antibody cytokine fusion proteins has demonstrated potent antitumor activity in numerous animal models and has led to the clinical development of 2 antibody-interleukin-2 (IL-2) fusion proteins. We previously reported on the construction and in vitro properties of a 'dual' cytokine fusion protein for simultaneous targeted delivery of human granulocyte macrophage-colony stimulating factor (GM-CSF) and IL-2 to human tumors. The fusion protein is based on a heterodimerized core structure formed by human CH1 and Ckappa domains (heterominibody) with C-terminally fused human cytokines and N-terminally fused single-chain antibody fragments specific for the tumor-associated surface antigen epithelial cell adhesion molecule (Ep-CAM). For testing the antitumor activity in syngeneic mouse xenograft models, we developed 'dual cytokine heterominibodies' with murine cytokines (mDCH). mDCH fusion proteins and, as controls, 'single cytokine heterominibodies' (SCH) carrying either murine GM-CSF (mGM-CSF) or murine IL-2 (mIL-2) were constructed, of which all retained the specific activities of cytokines and binding to the Ep-CAM antigen on human Ep-CAM transfected mouse colon carcinoma CT26-KSA cells. Over a 5-day treatment course, DCH fusion proteins induced significant inhibition of established pulmonary CT26-KSA metastases in immune-competent Balb/c mice at low daily doses of 1 mug of fusion protein per mouse. However, with the tested dosing schemes, antitumor activity of mDCH was largely independent of cytokine targeting to tumors as demonstrated by a control protein with mutated Ep-CAM binding sites. Single cytokine fusion proteins mSCH-GM-CSF and mSCH-IL-2 showed similar antitumor activity as the dual cytokine fusion protein mDCH, indicating that GM-CSF and IL-2 in one molecule did not significantly synergize in tumor rejection under our experimental conditions. Our results seem to contradict the notion that IL-2 and GM-CSF can synergize in antitumor activity and that with conventional dose regimens, their specific targeting to tumors, as tested here with 2 antibodies of different affinities, enhances their antitumor activity

Hypoxia induces c-fos transcription via a mitogen-activated protein kinase-dependent pathway

Müller JM, Krauss B, Kaltschmidt C, Baeuerle PA, Rupec RA. Hypoxia induces c-fos transcription via a mitogen-activated protein kinase-dependent pathway. J. Biol. Chem. 1997;272(37):23435-23439