Effect of temperature on invasion of MO4 mouse fibrosarcoma cells in organ culture.

Invasion by MO4 mouse fibrosarcoma cells into fragments of embryonic chick heart or lung in organ culture was studied histologically and ultrastructurally at various temperatures between 12 and 40 degrees C. Invasion was absent for at least 7 days at or below temperatures of 29 degrees C. Invasion was invariably observed at or above 30.5 degrees C. Differences in invasion between 29 and 30.5 degrees C could not be ascribed to differences in growth, migration, or microtubule assembly/disassembly of MO4 cells. Neither could they be explained through differences in the attachment of MO4 cells to the heart fragments. Possible explanations for the absence of invasion at lower temperature are: altered resistance of the extracellular matrix in heart or lung fragments, and deficient expression of fucosylated glycoproteins at the surface of MO4 cells. A population of MO4 cells plated from the parent line and adapted to grow at 28 degrees C (MO(4)28 cell line) did not differ in invasiveness from the parent MO4 cells. We conclude that the temperature dependence of invasion in organ culture might indicate as yet unexplored aspects of the mechanisms of tumour invasion.