3-DIMENSIONAL ANALYSIS OF THE SUBSTRATE-DEPENDENT INVASIVE BEHAVIOR OF A HUMAN LUNG-TUMOR CELL-LINE WITH A CONFOCAL LASER-SCANNING MICROSCOPE

Matrigel and collagen G gels were used as models for basement membrane and interstitial space-collagen, respectively, to study the invasive behavior of cells of the human lung tumor cell line EPLC 32M1, which w as derived from a squamous cell carcinoma. For three dimensional analy sis of the invasive process, cells were seeded onto the gels in a slid e chamber and observed with a confocal laser scanning microscope. Opti cal sectioning in the xy and xz directions and image reconstruction wi th computer programs allowed us readily to obtain a three-dimensional overview of the invasive process in situ. Both types of gel showed a s mooth surface. Matrigel had a granular structure whereas collagen G re vealed a fiber-like morphology. The tumor cells showed a matrix-depend ent behavior. On Matrigel, within 24 h of incubation, a network of cel ls appeared on the surface, which developed further within 72 h to int erconnected multicellular cords also invading the gel. Tumor cells see ded on collagen G remained individual. They formed pseudopodia and ach ieved tight contact with the matrix, eventually also invading the gels in a time-dependent manner, Therefore, the composition of the substra te crucially influences the invasion path.