INCREASING N-CAM-MEDIATED CELL-CELL ADHESION DOES NOT REDUCE INVASIONOF RSV-TRANSFORMED WC5 RAT CEREBELLAR CELLS

The WC5 rat cerebellar cell line, infected with a Rous sarcoma virus ( RSV) that is temperature-sensitive for pp60v-src transformation, expre sses high levels of the neural cell adhesion molecule, N-CAM, when gro wn at the non-permissive temperature for pp60v-src activity. At the pe rmissive temperature, N-CAM expression is 4- to 10-fold reduced and th e cells aggregate poorly. To evaluate the effects of variations in N-C AM expression, we compared the invasive ability of transformed WC5 cel ls that express low levels of N-CAM with transformed cells in which N- CAM-mediated adhesion was restored. WC5 cells were transfected with ex pression vectors containing cDNAs encoding the 120 or 180 kDa forms of chicken N-CAM linked to constitutive promoters. Several permanently t ransfected lines that expressed chicken N-CAM at the cell surface were isolated. These cell lines showed enhanced aggregation at the permiss ive temperature relative to untransfected WC5 cells or cells transfect ed with control constructs. By comparing the ability of control and tr ansfected WC5 cells to invade reconstituted extracellular matrix, we t ested the effect of variations in N-CAM-mediated adhesion on invasion. Clones that expressed high levels of N-CAM showed invasion rates that were similar to control cells, indicating that increasing N-CAM-media ted adhesion does not inhibit the invasiveness of RSV-transformed WC5 cells.