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Integrin expression and differentiation in transformed human epidermal cells is regulated by fibroblasts

1992; The Company of Biologists; Volume: 103; Issue: 3 Linguagem: Inglês

10.1242/jcs.103.3.755

1477-9137

Pritinder Kaur, W. G. Carter,

Cellular Mechanics and Interactions

ABSTRACT Normal human foreskin keratinocytes (HFKs) and transformed HFKs (FEPE1L-8 cells) generated by the introduction of cloned human papillomavirus type 16 sequences were compared for the expression and function of a family of adhesion receptors termed integrins. Initially, cells were examined in conventional monolayer cultures. FEPE1L-8s expressed integrins α1β1, α2β1, α3β1, α5β1, α6β4 and β1 at comparable levels to HFKs. Further, these receptors were fully functional in mediating specific interactions with exogenously supplied ligands. However, FEPE1L-8s exhibited decreased synthesis of a number of extracellular matrix components, including laminin, fibronectin and epiligrin, compared to normal HFKs, which may be an alternate mechanism for regulating adhesion. Subsequently, organotypic cultures (OCs), which provide a suitable in vitro model system for the ordered stratification and differentiation of keratinocytes, were used to study the regulation of integrins and various epidermal markers in normal and transformed cells. OCs consisted of keratinocytes plated on a collagen gel containing primary human fibroblasts, grown at an air-medium interface. Unlike normal HFKs, the transformed FEPE1L-8 cells exhibited (a) disorganized stratification and limited differentiation capacity, (b) invasion into the collagen gel, and (c) unregulated expression of α3β1 and α2β1, and underexpression of α6β4 integrins. Ordered stratification and spatial regulation of integrin expression could be induced in the FEPE1L-8s by substituting Swiss 3T3 fibroblasts in the collagen gel. Further data indicate that the human fibroblasts induce the transformed HFKs to invade into the collagen gel. We conclude that stromal cells play an important role in regulating (a) the differential expression of integrins, (b) the normal stratification and differentiation, and (c) the invasive behaviour of epidermal cells.