Phospholipids reduce adhesions of rodent colonic and human gastric cancer cells to extrcellular matrix components in vitro

M Jansen MD^a, KH Treutner MD^a, P Lynen-Jansen MD^b, B Schmitz^a, L Tietze MD^c, Prof Schumpelick^a

^aDepartment of Surgery, University Clinic, Pauwelsstr. 30, Aachen, Germany, ^bInterdisciplinary Center of Clinical Research, Biomat, Aachen, Germany, ^cInstitute of Pathology, University Clinic, Pauwelsstr. 30, Aachen, Germany

Aim: Nidation of floating tumor cells initiates peritoneal carcinosis and limits prognosis of gastrointestinal tumors. Adhesion of tumour cells to extracellular matrix components is a pivotal step in developing peritoneal dissemination of intraabdominal malignancies. Since phospholipids efficaciously prevented peritoneal adhesion formation in numerous animal studies we investigated their capacity to reduce adhesions of colonic and gastric cancer cells to extracellular matrix components. Methods: Cells from colonic adenocarcinoma induced in syngenic BD-IX rats (DHD/K12/TRb, European Collection of Animal Cell Cultures, ecacc, Salisbury, UK) and human gastric cancer cells (NUGC-4, Japanese Cancer Research Resources Bank, Tokyo, Japan) were used in this study. Microtiter plates were coated with collagen IV (coll), laminin (ln) and fibronectin (fn). Nonspecific protein binding of the coated wells was blocked by adding 1% (w/v) BSA (4°C, 12h) and rinsing the wells with Hepes buffer. According to dilution series, 30,000 - 70,000 tumor cells in 100 µl medium were seeded into each well. Beside the controls, phospholipids were added in concentrations of 0.05, 0.1, 0.5, 0.75, 1.0, and 1.5 mg / 100 µl medium After the incubation time of 30 min, attached cells were fixed and stained with 0.1% (w/v) crystal violet The dye was resuspended with 50 µl of 0.2% (v/v) Triton X-100 per well and colour yields were then measured in an ELISA reader at 590 nm. Optical density (OD) showed a linear relationship to the amount of cells and was corrected for dying of BSA/polystyrene without cells. Results: The controls revealed a significant increase of adhesions of both cell lines to the extracellular matrix components. The attachment of colonic and gastric cancer cells to collagen IV, laminin, and fibronectin could be significantly reduced up to 53% by phospholipid concentrations of 0.5 mg/µl and higher (ANOVA, p-level adhjusted to Bonferroni). Conclusion: These results within the scope of additional experimental studies on mice and rats which showed a significant reduction of peritoneal carcinosis demonstrated the capacity of phospholipids in controlling abdominal nidation of tumor cells. Lipid emulsions may be a beneficial adjunct in surgery of gastrointestinal malignancies.

Paper presented at the International Symposium on Predictive Oncology and Intervention Strategies; Nice, France; February 7 - 10, 2004; in oral session 898 (Oncogenesis).