We have been studying motility of tumor cells as a component of metastasis. Our goal is to identify proteins which are involved in motility. Two main approaches are being taken: (1) the identification of new proteins which are required for or enhance tumor cell motility in an animal model system and (2) the identification of proteins involved in the mechanism by which chemical gradients of adenosine and AMP stimulate the motility of human melanoma cells. The first approach involves a mutation screen in which single-site mutations are generated in Drosophila which are lacking the tumor suppressor gene lethal giant larvae. Brain fragments from lethal giant larvae mutants are highly metastatic when transplanted into adult hosts. These new mutants will then be screened to identify those mutations which cause either suppression or enhancement of brain tumor cell motility. These mutations are currently being generated by the insertion of single P elements. The P elements are engineered to facilitate cloning of flanking DNA sequences, which will allow the motility genes to be readily cloned. This approach will allow us to genetically dissect tumor cell motility in the Drosophila model system. The second approach involves the identification of the receptor which mediates the motility response of human melanoma A2058 cells to gradients of adenosine and AMP. Checkerboard analysis revealed that this motility was largely directed motility with a component of random motility. We have found evidence that the motility stimulation occurs through the adenosine receptor of the A1 subtype. This identification was based on the inhibition of adenosine and AMP-induced motility by two A1 adenosine receptor antagonists, CPX (8-Cyclopentyl-1,3-Dipropyl Xanthine) and CPT (Cyclopentyl-1,3-Dimethyl Xanthine). The adenosine receptor agonists CPA (N6-Cyclopentyladenosine), R-PIA [N6-(2-Phenylisopropyl)-Adenosine], 2-Chloroadenosine, and NECA [5'-(N-Ethylcarboxanido)-Adenosine] were also found to stimulate motility (approximately 50% of the level of AMP and adenosine), supporting the fact that adenosine receptors are present in the cell and that the stimulation of the receptor causes motility in A2058 melanoma cells. The adenosine and AMP-induced motility in these cells was found to be pertussis toxin sensitive, indicating that the signal transduction occurs through a G protein mediated pathway.
| Woodhouse, Elisa C; Fisher, Amy; Bandle, Russell W et al. (2003) Drosophila screening model for metastasis: Semaphorin 5c is required for l(2)gl cancer phenotype. Proc Natl Acad Sci U S A 100:11463-8 |
