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The [[alpha].sub.v][[beta].sub.3] integrin has been shown to promote cell migration through activation of intracellular signaling pathways. We describe here a novel pathway that modulates cell migration and that is activated by [[alpha].sub.v][[beta].sub.3] and, as downstream effector, by cdc2 (cdk1). We report that [[alpha].sub.v][[beta].sub.3] expression in LNCaP ([[beta].sub.3]-LNCaP) prostate cancer cells causes increased cdc2 mRNA levels as evaluated by gene expression analysis, and increased cdc2 protein and kinase activity levels. We provide three lines of evidence that increased levels of cdc2 contribute to a motile phenotype on integrin ligands in different cell types. First, increased levels of cdc2 correlate with more motile phenotypes of cancer cells. Second, ectopic expression of cdc2 increases cell migration, whereas expression of dominant-negative cdc2 inhibits migration. Third, cdc2 inhibitors reduce cell migration without affecting cell adhesion. We also show that cdc2 increases cell migration via specific association with cyclin B2, and we unravel a novel pathway of cell motility that involves, downstream of cdc2, caldesmon. cdc2 and caldesmon are shown here to localize in membrane ruffles in motile cells. These results show that cdc2 is a downstream effector of the [[alpha].sub.v][[beta].sub.3] integrin, and that it promotes cell migration.

Survivin, a new inhibitor of apoptosis (IAP) protein is found to be expressed in the C2/M stage of the cell cycle in a cycle-regulated way. Survivin associates with microtubules at the start of mitosis and disruption of the survivn-microtubule interaction leads to loss of the inhibitor's anti-apoptosis function. This suggests that it may counteract the default induction of apoptosis in G2/M phase.

The interface between apoptosis (programmed cell death) and the cell cycle is essential to preserve homeostasis and genomic integrity. Here, we show that survivin, an inhibitor of apoptosis over-expressed in cancer, physically associates with the cyclin-dependent kinase [p34.sup.cdc2] on the mitotic apparatus, and is phosphorylated on [Thr.sup.34] by [p34.sup.cdc2]-cyclin B1, in vitro and in vivo. Loss of phosphorylation on [Thr.sup.34] resulted in dissociation of a survivincaspase-9 complex on the mitotic apparatus, and caspase-9-dependent apoptosis of cells traversing mitosis. These data identify survivin as a mitotic substrate of [p34.sup.cdc2]-cyclin B1 and suggest that survivin phosphorylation on [Thr.sup.34] may be required to preserve cell viability at cell division. Manipulation of this pathway may facilitate the elimination of cancer cells at mitosis.

The α[sub v]β[sub 3] integrin has been shown to promote cell migration through activation of intracellular signaling pathways. We describe here a novel pathway that modulates cell migration and that is activated by α[sub v]β[sub 3] and, as downstream effector, by cdc2 (cdkl). We report that α[sub v]β[sub 3] expression in LNCaP (β[sub 3]-LNCaP) prostate cancer cells causes increased cdc2 mRNA levels as evaluated by gene expression analysis, and increased cdc2 protein and kinase activity levels. We provide three lines of evidence that increased levels of cdc2 contribute to a motile phenotype on integrin ligands in different cell types. First, increased levels of cdc2 correlate with more motile phenotypes of cancer cells. Second, ectopic expression of cdc2 increases cell migration, whereas expression of dominant-negative cdc2 inhibits migration. Third, cdc2 inhibitors reduce cell migration without affecting cell adhesion. We also show that cdc2 increases cell migration via specific association with cyclin B2, and we unravel a novel pathway of cell motility that involves, downstream of cdc2, caldesmon. cdc2 and caldesmon are shown here to localize in membrane ruffles in motile cells. These results show that cdc2 is a downstream effector of the α[sub v]β[sub 3] integrin, and that it promotes cell migration. [ABSTRACT FROM AUTHOR]

Survivin is a member of the inhibitor of apoptosis (IAP) gene family, which has been implicated in both preservation of cell viability and regulation of mitosis in cancer cells. Here, we show that HeLa cells microinjected with a polyclonal antibody to survivin exhibited delayed progression in prometaphase (31.5 +/- 6.9 min) and metaphase (126.8 +/- 73.8 min), as compared with control injected cells (prometaphase, 21.5 +/- 3.3 min; metaphase, 18.9 +/- 4.5 min; P < 0.01). Cells injected with the antibody to survivin displayed short mitotic spindles severely depleted of microtubules and occasionally underwent apoptosis without exiting the mitotic block or thereafter. Forced expression of survivin in HeLa cells profoundly influenced microtubule dynamics with reduction of pole-to-pole distance at metaphase (8.57 +/- 0.21 microm versus 10.58 +/- 0.19 microm; P < 0.0001) and stabilization of microtubules against nocodazole-induced depolymerization in vivo. These data demonstrate that survivin functions at cell division to control microtubule stability and assembly of a normal mitotic spindle. This pathway may facilitate checkpoint evasion and promote resistance to chemotherapy in cancer.