Effects of RA 233 treatment on the adhesive, invasive and metastatic properties of 13762NF rat mammary tumor cells.

The pyrimido-pyrimidine analogue RA 233 has pleiotropic and differential effects on cultured tumor cell clones isolated from the 13762NF rat mammary adenocarcinoma. A nonresponsive clone of low metastatic potential (MTC) was not modified in its cell fragility or invasive, adhesive or lung-colonizing properties by RA 233 treatment. In contrast, a drug-responsive clone of high metastatic potential (MTLn3) was rendered less invasive and its cell fragility was decreased with RA 233 treatment, although its adhesiveness to lung microvascular endothelial cells and subendothelial matrix was unaffected by RA 233. Lung colonization of intravenously injected MTLn3 cells in syngeneic rats was significantly increased by RA 233 treatment, whereas spontaneous metastasis from the mammary fat pad to lung sites was decreased, although this decrease was not statistically significant.