Fig. 4. Functional consequences of the progastrin-induced reduction in cell-cell adhesion. (A) Paracellular permeability, as assessed by [³H]mannitol flux through confluent monolayers, was reduced by almost 30% over a 24 hour period in DLD-1 colorectal carcinoma cells expressing antisense gastrin () compared with control cells transfected with vector only (•). The reduction was reversed by treatment with 5 nM progastrin_6-80 (), which had no effect on vector only cells (). (B) The permeability through a confluent monolayer of IMGE-5 cells was significantly increased after treatment with 5 nM progastrin_6-80 () compared with media alone (). Significance was assessed by Student's t test. *P<0.05; n=4. (C) When a confluent cell monolayer was wounded using a pipette tip, the spontaneous motility of DLD-1/VO clones (VO, columns 1, 2) over a 12 or 24 hour period was greatly reduced in clones expressing antisense gastrin (ASG, columns 3, 4). Motility was partly restored when the latter clones were treated with 5 nM progastrin_6-80 (ASG + PG, column 5). Bar, 60 µm. (D) When a confluent IMGE-5 monolayer was wounded using a pipette tip, treatment with 5 pM, 50 pM, 0.5 nM or 5 nM progastrin_6-80 (PG) over 12 or 24 hours increased cell motility compared with cells left untreated in DMEM containing 0.1% FCS (U). Bar, 60 µm.

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