Compounds identified by virtual docking to a tetrameric EGFR extracellular domain can modulate Grb2 internalization.

Background: Overexpression or mutation of the epidermal growth factor receptor (EGFR) potently enhances the growth of many solid tumors. Tumor cells frequently display resistance to mechanistically-distinct EGFR-directed therapeutic agents, making it valuable to develop therapeutics that work by additional mechanisms. Current EGFR-targeting therapeutics include antibodies targeting the extracellular domains, and small molecules inhibiting the intracellular kinase domain.

Human factors and pathways essential for mediating epigenetic gene silencing.

Cellular identity in both normal and disease processes is determined by programmed epigenetic activation or silencing of specific gene subsets. Here, we have used human cells harboring epigenetically silent GFP-reporter genes to perform a genome-wide siRNA knockdown screen for the identification of cellular factors that are required to maintain epigenetic gene silencing. This unbiased screen interrogated 21,121 genes, and we identified and validated a set of 128 protein factors.

Genome-wide siRNA screen reveals a new cellular partner of NK cell receptor KIR2DL4: heparan sulfate directly modulates KIR2DL4-mediated responses.

KIR2DL4 (CD158d) is a distinct member of the killer cell Ig-like receptor (KIR) family in human NK cells that can induce cytokine production and cytolytic activity in resting NK cells. Soluble HLA-G, normally expressed only by fetal-derived trophoblast cells, was reported to be a ligand for KIR2DL4; however, KIR2DL4 expression is not restricted to the placenta and can be found in CD56(high) subset of peripheral blood NK cells. We demonstrated that KIR2DL4 can interact with alternative ligand(s), expressed by cells of epithelial or fibroblast origin.

Synthetic lethal screen of an EGFR-centered network to improve targeted therapies.

Intrinsic and acquired cellular resistance factors limit the efficacy of most targeted cancer therapeutics. Synthetic lethal screens in lower eukaryotes suggest that networks of genes closely linked to therapeutic targets would be enriched for determinants of drug resistance. We developed a protein network centered on the epidermal growth factor receptor (EGFR), which is a validated cancer therapeutic target, and used small interfering RNA screening to comparatively probe this network for proteins that regulate the effectiveness of both EGFR-targeted agents and nonspecific cytotoxic agents.

PKC alpha-dependent regulation of the IGF1 receptor in adult and embryonic rat cardiomyocytes.

In both, the adult rat ventricular cardiomyocytes and the embryonic rat heart cell line, H9c2, acute exposure to IGF1 resulted in activation of the IGF1 receptor's internal tyrosine kinase, and this was completely blocked by the PKC alpha inhibitor, Gö6976. In addition, RNA interference using siRNA mediated gene silencing of PKC alpha-inhibited IGF1 receptor activity and blocked PKC alpha expression in H9c2 cells. Biochemical experiments demonstrate that PKC alpha is associated with the IGFlR (beta subunit) only after acute IGF1 exposure, and this may suggest that there is a direct interaction and possibly a PKC alpha phosphorylation site within the internal IGF1 receptor domain.

Alterations in insulin-like growth factor-I signaling in cardiomyocytes from chronic alcohol-exposed rats.

Background: Insulin-like growth factor-I (IGF-I) is a required cytokine for the development and maintenance of the cardiovascular system, and it may play a role in certain pathophysiological conditions.

Methods: Adult male rats were fed a liquid diet that contained 36% alcohol for 4 to 8 months, and their littermates served as isocaloric pair-fed controls, so we could examine IGF-I signaling in rat cardiomyocyte preparations.

Results: Recently, our laboratory reported that IGF-I activates protein kinase-C (PKC)-alpha and that PKC-alpha activity is required for IGF-I-dependent activation of Erk1/Erk2 and IGF-I-dependent protein synthesis.