The effect of a reconstituted basement membrane (Matrigel) on a human salivary gland myoepithelioma cell line

We have already demonstrated that a reconstituted basement membrane (Matrig el) is a key modulator of morphogenetic changes and cytodifferentiation of pleomorphic adenoma cells in culture. Myoepithelioma is considered to be a neoplasm closely related to pleomorphic adenoma and should experience simil ar induction processes. Thus, the aim of this study was to investigate whet her Matrigel would influence myoepithelioma cells. We used a cell line deri ved from a human salivary gland plasmacytoid myoepithelioma (M1 cells) grow n in a three-dimensional preparation of Matrigel. Phenotype differences wer e assessed using conventional light microscopy technique (haematoxylin and eosin) and phase and differential interference contrast (Nomarski). Immunof luorescence was carried out to detect smooth-muscle actin, laminin and type -IV collagen. M1 cells exhibited all proteins studied, showing a myoepithel ial differentiation. M1 cells grown inside Matrigel presented morphological changes and changes in smooth-muscle actin status. By growing M1 cells ins ide Matrigel, it was possible to reproduce the tumour architecture with no duct-like structures. Based on our findings, we suggest that myoepithelioma would be derived from a cell with a commitment to myoepithelial differenti ation. We also suggest that the mechanical properties of the matrix environ ment will likely regulate smooth-muscle actin expression in myoepithelioma.