Like many freely moving cells, Walker 256 carcinosarcoma cells respond to chemotactic stimuli. Since cyclic nucleotides are involved in the chemotaxis of other cells, we have examined the action of several nucleosides and nucleotides as chemoattractants and as modulators of tumor cell movement. We have also studied the effect of chemoattractants and prostaglandins on intracellular cyclic nucleotide levels and the effect of prostaglandins as modulators of chemotaxis. Of the agents studied, only the cyclic nucleotides and prostaglandins were found to modulate cellular motility. Neither cyclic adenosine 3′:5′-monophosphate (cAMP) nor cyclic guanosine 3′:5′-monophosphate (cGMP) was a chemoattractant, but cGMP and N6,O2′-dibutyryl cyclic guanosine 3′:5′-monophosphate at low concentrations (∼10-10m to 10-8m) enhanced chemotaxis by 80 ± 15%, and both cAMP and N6,O2′-dibutyryl cyclic adenosine 3′:5′-monophosphate had an inhibitory effect at concentrations >10-6m. Chemotaxis was suppressed by 21 to 100% in media depleted of Ca2+ and/or Mg2+, but in the presence of 10-8m cGMP, there was partial recovery of the chemotactic response. In response to chemotactic stimulation, there was a 28 to 60% rise in intracellular cAMP within 30 sec. This returned to basal levels within 2 min. Intracellular cGMP levels became elevated ∼3- to 3.5-fold after this time. Incubation of cells with prostaglandins A1 and F stimulated chemotaxis at lower concentrations (10-7 and 10-9m, respectively) and resulted in elevation of cGMP, while incubation with prostaglandin E2 resulted in inhibition of chemotaxis and a rise in cAMP levels.

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This work was supported by a grant from the National Cancer Institute of Canada.

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