(-)-Epigallocatechin-3-gallate (EGCg) has been implicated in cancer chemo-prevention in studies using many different kinds of cancer cells. The present study measured cell viability, osteopontin (OPN) secretion, fatty acid synthase (FAS) expression, and cytosolic Ca(2+) and verified the anti-cancer activities of EGCg in MCF-7 human breast cancer cells. EGCg-induced apoptosis was evidenced by nuclear condensation, increased protein levels of activated caspase-3, down-regulation of gelsolin and tropomyosin-4 (Tm-4), and up-regulation of tropomyosin-1(Tm-1). By disrupting adherens junction formation, EGCg caused accumulation of extra-nuclear β-catenin aggregates in the cytosol and alterations of the protein content and mRNA expression of E-cadherin and β-catenin, but not N-cadherin, in MCF-7 cells. To identify the putative mechanisms underlying the EGCg signaling pathways, EGFP (enhanced green fluorescence protein) was ectopically expressed in MCF-7 cells. This allowed us to monitor the EGCg-induced fluorescence changes associated with the effects of Triton X-100 (to remove plasma membrane) or the addition of laminin, anti-laminin receptor (LR) antibody, epidermal growth factor (EGF), and genistein on the cells. Our results indicated that EGCg acts via the signaling pathways associated with cell membrane to suppress cell proliferation, provoke apoptosis, and disturb cell-cell adhesion in MCF-7 cells. The altered events include the EGFR, LR, FAS, intracellular Ca(2+) , OPN secretion, caspace-3, gelsolin, Tm-4, Tm-1, and adherens junction proteins, E-cadherin and β-catenin.

We perform a series of simulations to study the effects of myosin minifilaments on the stress distribution in a crosslinked actin network. Previous theoretical studies suggest that the maximum tension generated per myosin depends strongly on the length of the myosin minifilaments and the actin filaments (A. E. Carlsson, Phys. Rev. E74, 051912, 2006). We study both two-and three-dimensional actin networks. The two-dimensional actin network is modeled as a collection of randomly oriented rods connected at their edges to a square frame. Before including the myosin-induced stresses, we studied the elastic response of the network under affine and nonaffine strain. The network structures are obtained by minimization of an energy function including terms due to both stretching and bending of rods. Rods are allowed to rotate without any energy cost at a crosslink where it connects to another rod. After energy minimization following a strain, forces and torques exerted by the network on the walls and Young's modulus of the network are calculated. The myosin forces are included by treating each myosin minifilament as a force dipole whose components act on different actin filaments. Then evaluation of the forces on the walls allows us to calculate the tension induced per myosin. These calculations allow us to understand the myosin induced stress as a function of structure of the network, by varying properties like connectivity, filament length, the extent of branching, and the treadmilling rate.