Objectives :To investigate the effect of BCG - PSN on the mechanical properties of adhesion between lung cancer cells and human umbilical vein endothelial cells. Methods: Micropipette aspiration technique was used to investigate quantitatively the adhesion force (Fa) and the relative adhesion stress (S1) between high metastatic human lung giant cell carcinoma (PG) cells or low metastatic lung adenocarcinoma (PAa) cells and human umbilical vein endothelial cells (HUVEC). Further

we Invistgated the effect of bacillus of Calmette and Guerin - polysaccharide nucleic acid (BCG - PSN) on Fa and S1. Results: The adhesion force (Fa) of PG cells to HUVEC were higher than that of PAa cells under the experimental condition. With treatment using BCG - PSN

the values of the adhesion force of PAa cells to HUVEC decreased in a concentration - dependent and time - dependent manner. For PG cells

treatment with a concentration of 50μg/ml or higher resulted in a continuous decrease of the cell adhesion force. And the adhesion force to HUVEC decreased continuously with the duration of treament from 30 minutes to 48 hours

but they increased significantly again in 72 hours after treatment. The relative adhesion stress between lung cancer cells and HUVEC

S1

changed almost in the same tendency as the adhesion force

Fa. Conclusion :The adhesion forces of PG cells to HUVEC were higher than that of PAa cells under the experimental condition. The adhesion forces of both of the lung cancer cells to HUVEC can be inhibited by BCG - PSN. These results might be relative to the high metastatic potential of PG cells through blood circulation

and to the antitumor action of HCG-PSN.