Environmental factors of temperature, humidity, serum accumulation, and cell seeding increase colon cancer cell adhesion in vitro, with partial characterization of the serum component responsible for pressure-stimulated adhesion.

Physical characteristics of surgical wounds and viable tumor cells shed may differ between open and laparoscopic procedures. Because environmental factors may vary between the laparoscopic milieu and that of open surgical procedures, we sought to characterize the effect of these factors on tumor cell adhesion, an early step in the process of wound implantation. Human SW620 colon cancer cells were placed in matrix-precoated dishes for 30 min at concentrations of 90,000-540,000 cells/well, at 25-37 degrees C, in the native state of the matrix proteins and after drying for 60 min, and in 0-10% serum. As increased pressure has previously been reported to stimulate colon cancer cell adhesion synergistically with serum, we then further partially characterized the serum components responsible for this potentiating effect. The number of adherent cells varied linearly with cells seeded. Adhesion was temperature-dependent, and also was dependent on the matrix conformation. Less adhesion occurred to dry matrix proteins. Serum dose-dependently potentiated SW620 pressure-stimulated adhesion, with a maximal increase in adhesion compared with ambient pressure conditions at 5% serum concentration. Heat inactivating the serum at 60 degrees C for 30 min ablated the effect. Filtration to remove molecules over 10 kDa produced no change in adhesion relative to ambient conditions, but filtration to 100 kDa preserved the serum effect. When the serum was passed over a gelatin-Sepharose column, which binds numerous proteins including fibronectin, the serum effect was lost. Addition of fibronectin to serum-free media did not reconstitute the effect. The environmental factors of warm temperature, moisture, and serum accumulation may contribute to increased colon cancer cell adhesion. However, the most important determinant of malignant adhesion to surgical wounds, laparoscopic or open, is likely to be the size of the tumor cell inoculum. Pressure stimulation of colon cancer cell adhesion is potentiated by heat-labile serum components of molecular weight 10-100 kDa which bind gelatin-Sepharose, and is not fibronectin alone. Irrigating serum from surgical wounds may decrease tumor implantation.