Regulation of membrane-type 1 matrix metalloproteinase expression by zonula occludens-2 in human lung cancer cells.

During tumor invasion, tumor epithelial cells acquire migratory and invasive properties involving important phenotypic alterations. Among these changes, one can observe reorganization or a loss of cell-cell adhesion complexes such as tight junctions (TJs). TJs are composed of transmembrane proteins (occludin, claudins) linked to the actin cytoskeleton through cytoplasmic adaptor molecules including those of the zonula occludens family (ZO-1, -2, -3). We here evaluated the potential role of ZO-2 in the acquisition of invasive properties by tumor cells. In vivo, we showed a decrease of ZO-2 expression in bronchopulmonary cancers, with a preferential localization in the cytoplasm. In addition, in vitro, the localization of ZO-2 varied according to invasive properties of tumor cells, with a cytoplasmic localization correlating with invasion. In addition, we demonstrated that ZO-2 inhibition increases invasive and migrative capacities of invasive tumor cells. This was associated with an increase of MT1-MMP. These results suggest that ZO-2, besides its structural role in tight junction assembly, can act also as a repressor of tumor progression through its ability to reduce the expression of tumor-promoting genes in invasive tumor cells.

The E-cadherin-repressed hNanos1 gene induces tumor cell invasion by upregulating MT1-MMP expression.

In this study, we examined the role of the E-cadherin-repressed gene human Nanos1 (hNanos1) in tumor invasion process. First, our in vivo study revealed that hNanos1 mRNAs were overexpressed in invasive lung carcinomas. Moreover, hNanos1 was co-localized with MT1-MMP (membrane type 1-matrix metalloproteinase) in E-cadherin-negative invasive lung tumor clusters. Using an inducible Tet-on system, we showed that induction of hNanos1 expression in DLD1 cells increased their migratory and invasive abilities in a three-dimensional migration and in a modified Boyden chamber assay. Accordingly, we demonstrated that hNanos1 upregulated MT1-MMP expression at the mRNA and protein levels. Inversely, using an RNA interference strategy to inhibit hNanos1 expression in invasive Hs578T, BT549 and BZR cancer cells, we observed a downregulation of MT1-MMP mRNA and protein and concomitantly a decrease of the invasive capacities of tumor cells in a modified Boyden chamber assay. Taken together, our results demonstrate that hNanos1, by regulating MT1-MMP expression, plays an important role in the acquisition of invasive properties by epithelial tumor cells.

Pseudomonas aeruginosa virulence factors delay airway epithelial wound repair by altering the actin cytoskeleton and inducing overactivation of epithelial matrix metalloproteinase-2.

To investigate the role of P. aeruginosa virulence factors in the repair of human airway epithelial cells (HAEC) in culture, we evaluated the effect of stationary-phase supernatants from the wild-type strain PAO1 on cell migration, actin cytoskeleton distribution, epithelial integrity during and after repair of induced wounds, and the balance between matrix metalloproteinases (MMP) and their tissue inhibitors (TIMP). PAO1 supernatant altered wound repair by slowing the migration velocity in association with altered actin cytoskeleton polymerization in the lamellipodia of migrating airway epithelial cells and delaying or inhibiting the restoration of epithelial integrity after wound closure. PAO1 virulence factors overactivated two of the gelatinolytic enzymes, MMP-2 and MMP-9, produced by HAEC during repair. During HAEC repair in the presence of PAO1 virulence factors, enhanced MMP-2 activation was associated with decreased rates of its specific inhibitor TIMP-2, whereas enhanced MMP-9 activation was independent of changes of its specific inhibitor TIMP-1. These inhibitory effects were specific to P. aeruginosa elastase-producing strains (PAO1 and lipopolysaccharide-deficient AK43 strain); supernatants from P. aeruginosa strain elastase-deficient PDO240 and Escherichia coli strain DH5alpha had no inhibitory effect. To mimic the effects of P. aeruginosa, we further analyzed HAEC wound closure in the presence of increasing concentrations of activated MMP-9 or MMP-2. Whereas increasing concentrations of active MMP-9 accelerated repair, excess activated MMP-2 generated a lower migration velocity. All these data demonstrate that P. aeruginosa virulence factors, especially elastase, may impede airway epithelial wound closure by altering cell motility and causing an imbalance between pro- and activated forms of MMP-2.