AN AUTOCRINE MOTILITY FACTOR SECRETED BY THE DUNNING R-3327 RAT PROSTATIC ADENOCARCINOMA CELL SUBTYPE-AT2.1

Tumor cell locomotion is an integral part of the metastatic process. We present a new autocrine motility factor (AMF) derived from the serum-free conditioned medium of the Dunning R-3327 rat prostate adenocarcinoma AT2.1 tumor cell subline AT2.1-AMF, prepared by concentration of components less-than-or-equal-to 30 kDa in size and washed free of low-molecular-weight growth factors, stimulated motility of AT2.1 cells in modified Boyden chamber migration assays. This stimulated migration was dose-dependent, and by checkerboard analysis was both chemotactic and chemokinetic. AT2.1-AMF activity was labile to heat, acid, base, reduction, oxidation, and proteases. Lyophilization and treatment with 6M urea caused a mild decrease (< 20%) in migration-stimulating capability. Tumor-cell specificity was demonstrated for AMF of AT2.1 and AT3.1 Dunning sublines, and the A2058 human melanoma cell lines. AT2.1 cell migration to AT2.1-AMF was inhibited by 2 hr pre-treatment with chlorea toxin (0.1-mu-g/ml) or forskolin (100-mu-M), but not altered by 2 hr pre-treatment with pertussis toxin (1.0-mu-g/ml). This indicates that guanine nucleotide binding protein-mediated regulation of cAMP is involved in modulating the AT2.1 cell response to its AMF. The AT2.1-AMF belongs to a related family of tumor autocrine motility factors and represents a new model for understanding the role of tumor-cell migration in the metastatic process of human prostate cancer.