HUMAN MCAF GENE-TRANSFER ENHANCES THE METASTATIC CAPACITY OF A MOUSE CACHECTIC ADENOCARCINOMA CELL-LINE IN-VIVO

Purpose. To evaluate the effect of monocyte chemotactic and activating factor (MCAF/MCP-1/JE) on tumor progression and metastasis. Methods. Cachexia-inducing adenocarcinoma cells (cell line colon 26, clone 20) were transfected with either a control plasmid or MCAF expression vect or. Spontaneous lung metastases were determined in mouse. Results. The production of MCAF reached 0.4 ng/ml in vitro when transfectant cells were cultured at a cell density of 5 x 10(4) cells/ml for 3 days. Tra nsfection of MCAF expression vector did not affect the growth rate in vitro. Also, after MCAF-transfection, the size of tumors after intra-f ootpad inoculation was similar to that of the parental cells. When the primary tumors were resected on the 10th day after inoculation, the i ncidence of spontaneous lung metastasis was less than 20% in both cell s. The number of endothelial cells in the primary tumor rapidly increa sed from the 10th to the 14th day after inoculation, as revealed by im munohistochemical staining. In accordance with enhanced angiogenesis, the incidence rates of spontaneous metastasis increased when the prima ry tumors were resected on the 14th day after inoculation. Moreover, t he spontaneous lung metastases were augmented in the animals injected with MCAF-transfectants compared to those injected with parental cells with a concomitant increase of angiogenesis. Conclusions. These resul ts suggest that MCAF may augment the metastatic potential by modulatin g tumor associated angiogenesis.