Background: Engineered iron nanoparticles are being explored for the development of biomedical applications and many other industry purposes. However, to date little is known concerning the precise mechanisms of translocation of iron nanoparticles into targeted tissues and organs from blood circulation, as well as the underlying implications of potential harmful health effects in human.

. Expression of CDK6 and ␤-actin was not affected by LY-294002. Expression of the cyclin kinase inhibitor p16 INK4a was induced by the PI3K inhibitor, whereas steady-state levels of p21 CIP1/WAF1 were decreased in the same experiment. The inhibition of PI3K activity also inhibited the phosphorylation of AKT and p70S6K1, but not extracellular regulated kinase 1/2. The G 1 cell cycle arrest induced by LY-294002 was restored by the expression of active forms of AKT and p70S6K1 in the cells. Our study shows that PI3K transmits a mitogenic signal through AKT and mammalian target of rapamycin (mTOR) to p70S6K1. The mTOR inhibitor rapamycin had similar inhibitory effects on G 1 cell cycle progression and on the expression of cyclin D1, CDK4, CDC25A, and retinoblastoma phosphorylation. These results indicate that PI3K mediates G 1 progression and cyclin expression through activation of an AKT/mTOR/p70S6K1 signaling pathway in the ovarian cancer cells. phosphatidylinositol 3-kinase; cyclin-dependent kinases; retinoblastoma protein OVARIAN CANCER IS THE LEADING cause of death from gynecological malignancy and the fourth most common cause of cancer death among American women (40). Recent observations indicate that the gene encoding the p110␣ catalytic subunit of phosphatidylinositol 3-kinase (PI3K) is increased in copy number in ϳ40% of primary ovarian cancer cells and several ovarian epithelial carcinoma cell lines. The PI3K inhibitor LY-294002 has been shown to inhibit growth of an ovarian cancer cell line in vitro (48). PI3K is a heterodimeric enzyme composed of 110-kDa catalytic and 85-kDa regulatory subunits (3). PI3K phosphorylates the D3 hydroxyl of phosphoinositides and produces phosphatidylinositol-3-phosphate. PI3K

Beta-elemene is a novel anticancer drug, which was extracted from the ginger plant. However, the mechanism of action of beta-elemene in non-small-cell lung cancer (NSCLC) remains unknown. Here we show that beta-elemene had differential inhibitory effects on cell growth between NSCLC cell lines and lung fibroblast and bronchial epithelial cell lines. In addition, beta-elemene was found to arrest NSCLC cells at G2-M phase, the arrest being accompanied by decreases in the levels of cyclin B1 and phospho-Cdc2 (Thr-161) and increases in the levels of p27(kip1) and phospho-Cdc2 (Tyr-15). Moreover, beta-elemene reduced the expression of Cdc25C, which dephosphorylates/activates Cdc2, but enhanced the expression of the checkpoint kinase, Chk2, which phosphorylates/ inactivates Cdc25C. These findings suggest that the effect of beta-elemene on G2-M arrest in NSCLC cells is mediated partly by a Chk2-dependent mechanism. We also demonstrate that beta-elemene triggered apoptosis in NSCLC cells. Our results clearly show that beta-elemene induced caspase-3, -7 and -9 activities, decreased Bcl-2 expression, caused cytochrome c release and increased the levels of cleaved caspase-9 and poly(ADP-ribose) polymerase in NSCLC cells. These data indicate that the effect of beta-elemene on lung cancer cell death may be through a mitochondrial release of the cytochrome c-mediated apoptotic pathway.

This study was designed to identify the molecular mechanisms of phosphatidylinositol 3-kinase (PI3K)-induced actin filament remodeling and cell migration. Expression of active forms of PI3K, v-P3k or Myr-P3k, was sufficient to induce actin filament remodeling to lead to an increase in cell migration, as well as the activation of Akt in chicken embryo fibroblast (CEF) cells. Either the inhibition of PI3K activity using a PI3K-specific inhibitor, LY-294002, or the disruption of Akt activity restored the integrity of actin filaments in CEF cells and inhibited PI3K-induced cell migration. We also found that expression of an activated form of Akt (Myr-Akt) was sufficient to remodel actin filaments to lead to an increase in cell migration, which was unable to be inhibited by the presence of LY-294002. Furthermore, we found that p70S6K1 kinase was a downstream molecule that can mediate the effects of both PI3K and Akt on actin filaments and cell migration. Overexpression of an active form of p70S6K1 was sufficient to induce actin filament remodeling and cell migration in CEF cells, which requires Rac activity. These results demonstrate that activation of PI3K activity alone is sufficient to remodel actin filaments to increase cell migration through the activation of Akt and p70S6K1 in CEF cells.

Transformation of chicken embryo cells by oncogenic forms of pp64Yrc (e.g., pp60V" or The Rous sarcoma virus transforming gene product, pp6Ovsrc, is both necessary and sufficient for transformation (reviewed in reference 33). The transforming capacity of pp60 is dependent upon activation of tyrosine kinase catalytic function, its association with cell membranes (7), and its ability to stably associate with cellular proteins (22). Regulation of the tyrosine kinase activity is accomplished by phosphorylation of a carboxyl-terminal tyrosine residue, Tyr-527, a residue that is missing from pp6ovsrc (51). In pp6OCSrCs, mutation of Y-527 to phenylalanine (pp60527F) results in a transformation-competent form of pp60 that displays an elevated tyrosine-specific kinase activity both in vitro and in vivo (5,25,36,40). Membrane association of Src proteins requires the myristylation of a glycine residue at amino acid position 2. Mutations that change this glycine residue to alanine prevent myristylation and membrane association and block the transforming capacity of pp6ovsrc and pp60527F (2-4, 19, 39, 46 with another tyrosine-phosphorylated cellular protein, ppl3O) forms a stable complex with activated pp6Orc (22,38). The stable association of AFAP-110 in vivo requires the structural integrity of the SH3 and SH2 (Src homology 3 and 2) domains of pp60Yrc. The SH3 and SH2 domains are conserved not only among the Src family of nonreceptor tyrosine kinases (26) but also among a number of proteins known to participate in signal transduction, e.g., the GTPase-activating protein (52, 53), phospholipase C--y (50), phosphatidylinositol 3-kinase (17, 24, 31), and the oncoprotein pp47-Crk (30).A monoclonal antibody (MAb 4C3) specific for AFAP-110 has been used to characterize the intracellular localization of AFAP-llO, the steady-state level of phosphorylation, and its association with pp60Orc (21, 22). AFAP-110 is associated with actin stress fibers in normal CE cells and, upon transformation by pp6Orc, undergoes a striking rearrangement in cellular localization into rosette-like structures referred to as podosomes (8,22). The redistribution of AFAP-110 in Srctransformed cells is similar to that observed for actin filaments and other cytoskeleton-associated proteins (1,11,22). In Src-transformed CE cells, AFAP-110 is tyrosine phosphorylated and forms stable complexes with activated forms of pp6Q"rc. Tyrosine phosphorylation of AFAP-110 and its association with pp6o0rc are not observed in cells infected with transformation-defective variants of pp6Q"rc that contain deletions within the SH3 or SH2 domain (22). The stable association between AFAP-110 and pp6Orc correlates with the fully transformed phenotype of Src-transformed cells. 7892on May 11, 2018 by guest