Cell-matrix interactions of normal and transformed human keratinocytes in vitro are modulated by the synthetic phospholipid analogue hexadecylphosphocholine.

We have investigated the effect of the synthetic phospholipid analogue, hexadecylphosphocholine (HePC), a member of a new class of membrane-affecting antiproliferative drugs, on adhesion to extracellular matrix components, reorganization of three-dimensional collagen lattices, and proliferative activity of human keratinocyte populations in vitro. Six transformed keratinocyte lines were compared with their normal counterparts from interfollicular epidermis. Adhesion to collagen types I and IV, laminin, and fibronectin was weakest in normal keratinocytes (binding of 3-10% of the cells), followed by HaCaT and HaCaT-II/3 (25-30% binding), and the squamous carcinoma lines and SV-40 transformed keratinocytes (35-50% binding). Treatment with non-toxic doses of 10-20 mumol/l HePC led to a clear inhibition of the adhesive interactions by 50-75% in all populations. The impaired adhesion capacity was paralleled by a clear decrease of the ability of all keratinocyte populations to contract three-dimensional collagen lattices, an experimental model system for the reorganization of extracellular matrices. Histological examination revealed that these effects were due to a reduced cell number in the collagen lattices, a finding underscored by significant inhibition of proliferative activity of all keratinocyte populations by HePC. Furthermore, HePC led to marked changes of cellular morphology in the contracted gels. FACS analysis revealed that the impaired interaction with components of the extracellular matrix was not due to a specific downregulation of beta 1-integrins, the major cell-surface receptors for the respective matrix proteins. In conclusion, our results provide new insights into the potential action of HePC in a variety of skin disorders. Decreased proliferative activity and changes of cellular morphology, combined with impaired interactions with extracellular matrix proteins and a consecutive loss of matrix organization capacity, may cause suppression of different hyperproliferative skin diseases.