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Angiogenesis, the growth of new blood vessels from the existing vasculature, is necessary for normal growth and development and in the adult during wound healing and the reproductive cycles. In most adult tissues, however, the vasculature is maintained in a quiescent state by the balanced presence of both angiogenic inducers and inhibitors in the tissue milieu. For progressive growth and metastasis, cancer cells must shift this balance to favor angiogenic induction. When inducers predominate, vascular endothelial cells (VECs) become activated, proliferating and migrating toward the source of the angiogenic inducer. In the activated VECs, distinct cell signaling pathways are initiated compared with that of quiescent VECs, providing the specificity of anti-angiogenic therapies to the tumor vasculature. VEC apoptosis has been well documented in regressing vessels, and it has been shown that, in addition to activating the VECs, some inducers such as vascular endothelial growth factor also up-regulate Fas expression, thus sensitizing the cell to apoptotic stimuli. Endogenous angiogenesis inhibitors, such as thrombospondin-1 (TSP-1) and pigment epithelium-derived factor (PEDF), stimulate signaling cascades within the VECs and also induce the expression of Fas ligand in activated VECs. Therefore, when inhibitors predominate, the apoptotic cascade is initiated. Depleting the supply of angiogenic inducers can also induce apoptosis, and thus, anti-angiogenic therapies can target the inducer supply or directly target the VECs. Although clinical studies are promising, most to date suggest that anti-angiogenic therapies may prove to be most effective when used in combination with traditional therapies.

Increased tissue factor (TF) expression is observed in many types of cancer, associated with more aggressive disease, and in thrombosis. The mechanism by which TF promotes tumor growth remains unclear. Anticoagulation has been shown to result in a trend toward improved survival; no direct antitumor effect has been shown in cancer patients. Alternatively spliced tissue factor (asTF) was recently described, in which exon 5 is deleted. Because of a frame-shift in exon 6, the transmembrane and cytoplasmic domains are replaced with a unique COOH-terminal domain, making asTF soluble. Both alternatively spliced human tissue factor (asHTF) and full-length tissue factor (flTF) are expressed in human pancreatic cancer lines and in pancreatic cancer specimens. We studied the role of asHTF and flTF in a mouse model of pancreatic cancer. Although lacking procoagulant activity, asTF promotes primary growth of human pancreatic cancer cells in mice and augments tumor-associated angiogenesis. This body of work suggests a new paradigm for the role of TF in pancreatic cancer: that asHTF contributes to cancer growth, independent of procoagulant activity.

We have demonstrated previously that class I A phosphoinositide 3-kinases play a major role in regulation of interleukin-3 (IL)-3-dependent proliferation. Investigations into the downstream targets involved have identified the MAPK cascade as a target. Expression of ⌬p85 and incubation with LY294002 both inhibited IL-3-induced activation of Mek, Erk1, and Erk2. This was most pronounced during the initial phase of Erk activation. The Mek inhibitor, PD98059, blocked IL-3-driven proliferation, an effect enhanced by ⌬p85 expression, suggesting that inhibition of Mek and Erks by ⌬p85 contributes to the decrease in IL-3-induced proliferation in these cells but that additional pathways may also be involved. To investigate the mechanism leading to decreased activation of Erks, we investigated effects on SHP2 and Gab2, both implicated in IL-3 regulation of Erk activation. Expression of ⌬p85 led to a reduction in SHP2 tyrosine phosphorylation and its ability to interact with Grb2 and Gab2 but increased overall tyrosine phosphorylation of Gab2. LY294002 did not perturb SHP2 interactions, potentially related to differences in the effects of these inhibitors on levels of phosphoinositides. These results imply that the regulation of Erks by class I A phosphoinositide 3-kinase may contribute to IL-3-driven proliferation and that both SHP2 and Gab2 are possibly involved in this regulation.The survival, proliferation, and differentiation of cells of the hemopoietic cell compartment is regulated by the actions of a diverse range of cytokines. We and others (1, 2) have focused on the actions of interleukin-3 (IL-3), 1 which acts on cells of the myeloid lineage and is important for the survival and proliferation of mast cells and basophils. IL-3 induces the activation of a number of signaling cascades (reviewed in Ref. 3), including the Ras/Raf/MEK/MAPK module (4, 5) and the class I A phosphoinositide 3-kinase family (6, 7). Recent challenges have been to determine the functional requirement of these pathways in IL-3 action.Phosphoinositide 3-kinases are a family of lipid kinases, whose products, phosphoinositide 3,4-bisphosphate (PI(3,4)P 2 ) and phosphoinositide 3,4,5-triphosphate (PI(3,4,5)P 3 ), are important intracellular second messengers (8). IL-3 activates members of the class I A family of PI3Ks, which consist of a regulatory subunit (p85) and a 110-kDa catalytic subunit (8). Three forms of p110 (␣, ␤, and ␦) have been identified, with the p110␦ isoform being largely restricted in its expression to cells of the immune system (7, 9). PI3Ks have been implicated in regulating a broad range of physiological processes, including the control of proliferation, cell survival, vesicle trafficking, and glucose transport. We reported previously that expression of dominant negative p85 (⌬p85), which specifically targets class I A PI3Ks, results in a dramatic reduction in IL-3-induced proliferation (10), accompanied by reduced activation of protein kinase B and a concomitant decrease in the phosphorylation of the pro-apoptotic Bcl-2 fa...

A statistical method to estimate DNA copy number from Illumina high-density methylation arrays, Systems Biomedicine, 1:2, 94-98,