Analysis of changes induced by oncogene <Emphasis Type="Italic">N-RAS</Emphasis> expression in pattern and distribution of pseudopodial activity of fibroblasts

It is not known which morphological properties of fibroblasts induced by malignant transformation modulate their migration pattern. We studied the changes in the distribution and dynamics of the leading edge of 10(3) mouse fibroblasts after their transformation by oncogene N-RAS ^asp13 and analyzed the changes in the pattern of cell migration. Transformation proved to increase the leading edge proportion and to considerably redistribute pseudopodial activity along the cell edge. As the result of transformation, small pseudopodia are formed in the stable lateral regions of the cell edge typical of normal fibroblasts, i.e., the lateral edge is no more truly stable. In addition, pseudopodial activity of the leading edge in transformed fibroblasts proved higher compared to normal ones. It is necessary to notice, the leading edge activity is equally high immediately after induction in both normal and transformed fibroblasts; although, it is suppressed with time in normal cells but not in transformed ones where it remains steadily high. These properties promote the random component of malignant cell motility and modify the cell migration pattern after transformation