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Alphav and beta1 integrins regulate dynamic compression-induced proteoglycan synthesis in 3D gel culture by distinct complementary pathways.

ABSTRACT: Our goal was to test the hypothesis that specific integrin receptors regulate chondrocyte biosynthetic response to dynamic compression at early times in 3D gel culture, during initial evolution of the pericellular matrix, but prior to significant accumulation of further-removed matrix. The study was motivated by increased use of dynamic loading, in vitro, for early stimulation of tissue engineered cartilage, and the need to understand the effects of loading, in vivo, at early times after implantation of constructs.Bovine articular chondrocytes were seeded in 2% agarose gels (15x10(6)cells/mL) and incubated for 18 h with and without the presence of specific integrin blockers (small-molecule peptidomimetics, function-blocking antibodies, and RGD-containing disintegrins). Samples were then subjected to a 24-h dynamic compression regime found previously to stimulate chondrocyte biosynthesis in 3D gel as well as cartilage explant culture (1 Hz, 2.5% dynamic strain amplitude, 7% static offset strain). At the end of loading, proteoglycan (PG) synthesis ((35)S-sulfate incorporation), protein synthesis ((3)H-proline incorporation), DNA content (Hoechst dye 33258) and total glycosaminoglycan (GAG) content (dimethyl methylene blue (DMMB) dye binding) were assessed.Consistent with previous studies, dynamic compression increased PG synthesis and total GAG accumulation compared to free-swelling controls. Blocking alphavbeta3 abolished this response, independent of effects on controls, while blocking beta1 abolished the relative changes in synthesis when changes in free-swelling synthesis rates were observed.This study suggests that both alphavbeta3 and beta1 play a role in pathways that regulate stimulation of PG synthesis and accumulation by dynamic compression, but through distinct complementary mechanisms.

SUBMITTER: Chai DH

PROVIDER: S-EPMC2818306 | biostudies-literature | 2010 Feb

REPOSITORIES: biostudies-literature

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Alphav and beta1 integrins regulate dynamic compression-induced proteoglycan synthesis in 3D gel culture by distinct complementary pathways.

Chai D H DH Arner E C EC Griggs D W DW Grodzinsky A J AJ

Osteoarthritis and cartilage 20090922 2

<h4>Objective</h4>Our goal was to test the hypothesis that specific integrin receptors regulate chondrocyte biosynthetic response to dynamic compression at early times in 3D gel culture, during initial evolution of the pericellular matrix, but prior to significant accumulation of further-removed matrix. The study was motivated by increased use of dynamic loading, in vitro, for early stimulation of tissue engineered cartilage, and the need to understand the effects of loading, in vivo, at early t ...[more]

PMID: 19800448

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Project description:Interactions between cancer cells and stroma are critical for growth and invasiveness of epithelial tumors. The biochemical mechanisms behind tumor-stromal interactions leading to increased invasiveness and metastasis are mostly unknown. The goal of this study was to analyze the direct effects of staged stroma-derived extracellular matrices on breast cancer cell behavior.Early and late three-dimensional matrices were produced by NIH-3T3 and tumor-associated murine fibroblasts, respectively. After removing fibroblasts, extracted matrices were re-cultured with breast epithelial cells of assorted characteristics: MCF-10A (non-tumorigenic), MCF-7 (tumorigenic, non-invasive), and MDA-MB-231 (tumorigenic, invasive). Effects prompted by staged matrices on epithelial cell's growth, morphology and invasion were determined. Also, matrix-induced velocity, directionality and relative track orientation of invasive cells were assessed in the presence or absence of inhibitors of phosphoinositide-3 kinase (PI3K) and/or beta-1 integrin.We observed that assorted breast epithelial cells reacted differently to two-dimensional vs. staged, control (early) and tumor-associated (late), three-dimensional matrices. MCF-10A had a proliferative advantage on two-dimensional substrates while MCF-7 and MDA-MB-231 showed no difference. MCF-10A and MCF-7 formed morphologically distinguishable aggregates within three-dimensional matrices, while MDA-MB-231 exhibited increased spindle-shape morphologies and directional movements within three-dimensional matrices. Furthermore, MDA-MB-231 acquired a pattern of parallel oriented organization within tumor-associated, but not control matrices. Moreover, tumor-associated matrices induced PI3K and beta1-integrin dependent Akt/PKB activity in MDA-MB-231 cells. Interestingly, beta1-integrin (but not PI3K) regulated tumor-associated matrix-induced mesenchymal invasion which, when inhibited, resulted in a change of invasive strategy rather than impeding invasion altogether.We propose that both cells and matrices are important to promote effective breast cancer cell invasion through three-dimensional matrices and that beta1-integrin inhibition is not necessarily sufficient to block tumor-matrix induced breast cancer cell invasion. Additionally, we believe that characterizing stroma staging (e.g., early vs. late or tumor-associated) might be beneficial for predicting matrix-induced cancer cell responses in order to facilitate the selection of therapies.

Dataset Information

Alphav and beta1 integrins regulate dynamic compression-induced proteoglycan synthesis in 3D gel culture by distinct complementary pathways.

Publications

Alphav and beta1 integrins regulate dynamic compression-induced proteoglycan synthesis in 3D gel culture by distinct complementary pathways.

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