Transforming Growth Factor β1 Alters Calcium Mobilizing Properties and Endogenous ATP Release in A549 Cells: Possible Implications for Cell Migration

Abstract

Abstract. We examined the effects of transforming growth factor β 1 (TGF β 1 ) on cellular functions in human lung cancer cell line A549. Treatment of A549 cells with 1 ng/ml TGF β 1 for more than 3 days altered their morphology from an epithelial cobblestone-like appearance to a fibroblastlike one, reduced the expression of E-cadherin mRNA and protein, and induced the formation of F-actin fibers. These hallmarks indicate that TGF β 1 induced the epithelial-mesenchymal transition in A549 cells. Migration of TGF β 1 -treated A549 cells, which was quantified by the wound-healing assay, was markedly accelerated by 3 μ M ATP γ S, a non-hydrolyzable ATP analogue. ATP γ Sinduced migration of TGF β 1 -treated A549 cells was reversed by the P2 antagonist suramin. In contrast, migration of control A549 cells was not altered by ATP γ S. TGF β 1 -treated A549 cells showed an augmentation of ATP-induced Ca 2+ transients, thapsigargin-induced Ca 2+ transients, and store-operated Ca 2+ entry compared with those in control cells. Basal level of the extracellular ATP concentration was significantly lower in TGF β 1 -treated A549 cells than in control cells. We conclude from these results that TGF β 1 augments ATP-induced Ca 2+ mobilization, which leads to the acceleration of migration, in A549 cells but, it markedly reduces endogenous ATP release. This implies that the actions of ATP would become a novel therapeutic target for inhibiting cancer cell migration.

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