Plasma membrane microviscosity of Lewis lung carcinoma cells derived from local growth and pulmonary metastases.

Significant differences in plasma membrane microviscosity between 3LL Lewis lung carcinoma cells, grown at the site of their original inoculation (1-3LL), and the pulmonary metastatic cells of this tumor (m-3LL) were detected by a recent improvement of the fluorescence polarization technique, especially designed for cells in suspension. Membrane microviscosity was also found to depend on the site of the growth and the stage of tumor development. The results show that lung metastases are lower in membrane microviscosity compared to 1-3LL and that, within the latter, cells grown in the muscle are characterized by higher microviscosity than those grown under the skin or in the footpad. Within one transplantation period, 3LL tumor cells tend to acquire membrane microviscosity values typical of the anatomical location of tumor growth. Tumors at advanced stages were generally found to be more rigid than young ones, where tumor size (volume) rather than its age seemed to determine the membrane microviscosity. These differences are discussed in terms of both the causes and the biological, as well as immunological, implications in relation to the newly proposed hypothesis of passive modulation of antigenic expression.