Genistein-stimulated adherence of prostate cancer cells is associated with the binding of focal adhesion kinase to beta-l-integrin

Abstract

The isoflavinoid genistein is a protein-tyrosine kinase inhibitor which has been identified as a putative cancer prevention agent. Its consumption is associated with a low incidence of clinical metastatic prostate cancer in the face of a sustained high incidence of organ-confined prostate cancer. We therefore undertook studies to examine genistein's effect upon cell adhesion as one possible mechanism by which it could be acting as an antimetastatic agent. A morphogenic analysis revealed that genistein caused cell flattening in a variety of cell lines: PC3-M, PC3, and DU-145 prostate carcinoma cells, as well as MCF-7 breast carcinoma cells. Mechanistic studies focused on the highly metastatic PC3-M cell line, and revealed that cell flattening was accompanied by an increase in cell adhesion. Further investigations demonstrated that focal adhesion kinase (FAK) accumulated in areas of focal cell attachment, and that this accumulation occurred only when cells were actively undergoing genistein-mediated morphologic change. Concurrent formation of a complex between the cell attachment molecule, beta-1-integrin, and FAK was shown to occur, and to correlate with transient activation of FAK activity. Genistein is presented as a novel investigative tool for use in the study of molecular events involved in the process of cell adhesion.

Prostate cancer chemoprevention agents exhibit selective activity against early stage prostate cancer cells

“…33,34 The PC3-M cell line is a well-characterized variant of the PC3 cell line and represents a more rapidly growing metastatic variant of the parental cells. 12,13,18 While widely reported in the literature, the LNCaP cell line was not subjected to phenotypic analysis in this study. This is because the current focus was not upon identi®cation of androgen receptor binding agents and there was concern that tamoxifen may exhibit promiscuous receptor activation, as has been reported with a variety of agents.…”

“…51 ± 53 (2) Genistein possesses antimetastatic activity in prostate, is also growth inhibitory, and is currently undergoing phase I testing as a potential prostate chemopreventive agent. 13,18,54 (3) Tamoxifen, at high concentrations (ie, micromolar range), inhibits protein kinase C (PKC), activating prostate TGFb signaling pathways and leading to growth inhibition, and when given to humans in the form of high dose tamoxifen therapy, is associated with clinical activity in advanced prostate cancer. 17,55 Toremifene and 4-hydroxy tamoxifen, are chemically related to tamoxifen.…”

“…18 Brie¯y, exponentially growing non-con¯uent cells were detached by treatment with trypsin/EDTA and adjusted to 10 5 cells/ml. 100 ml of cell suspension were then added to each well of a 96-well plate; plates were either coated with 1 mg/cm 2 ®bronectin or not, as indicated.…”

“…18 Brie¯y, 6610 3 cells in 250 ml culture media were plated into each well of an eight chamber tissue culture slide (Franklin Labs, Franklin Lakes, NJ). Cells were then cultured for 24 ± 48 h under conditions of exponential growth and subcon¯uence.…”

“…13,18 To determine if cell growth was associated with metastatic potential, the ability of cells to adhere to a solid matrix was measured. As can be seen in Figure 1, the highly metastatic PC3-M cell variant ®rst attached more rapidly than all other cell types, then entered a phase of spontaneous cell detachment.…”