PTP-PEST controls motility, adherens junction assembly, and Rho GTPase activity in colon cancer cells.
An important step in carcinoma progression is loss of cell-cell adhesion leading to increased invasion and metastasis. We show here that the protein tyrosine phosphatase, PTP-PEST, is a critical regulator of cell-cell junction integrity and epithelial cell motility. Using colon carcinoma cells, we show that the expression level of PTP-PEST regulates cell motility. Either transient small interfering RNA or stable short hairpin RNA knockdown of PTP-PEST enhances haptotactic and chemotactic migration of KM12C colon carcinoma cells. Furthermore, KM12C cells with stably knocked down PTP-PEST exhibit a mesenchymal-like phenotype with prominent membrane ruffles and lamellae. In contrast, ectopic expression of PTP-PEST in KM20 or DLD-1 cells, which lack detectable endogenous PTP-PEST expression, suppresses haptotactic migration. Importantly, we find that PTP-PEST localizes in adherens junctions. Concomitant with enhanced motility, stable knockdown of PTP-PEST causes a disruption of cell-cell junctions. These effects are due to a defect in junctional assembly and not to a loss of E-cadherin expression. Adherens junction assembly is impaired following calcium switch in KM12C cells with stably knocked down PTP-PEST and is accompanied by an increase in the activity of Rac1 and a suppression of RhoA activity in response to cadherin engagement. Taken together, these results suggest that PTP-PEST functions as a suppressor of epithelial cell motility by controlling Rho GTPase activity and the assembly of adherens junctions.
Sealy Center for Cancer Cell Biology, University of Texas Medical Branch, Galveston, Texas 77555-1074, USA.
Rosario
R
Espejo
William
W
Rengifo-Cam
Michael D
MD
Schaller
B Mark
BM
Evers
Sarita K
SK
Sastry
D022005:Adherens Junctions / Q000201:enzymology / Q000378:metabolism / Q000502:physiology*; D000818:Animals; D045744:Cell Line, Tumor; D002464:Cell Migration Inhibition / Q000502:physiology*; D002465:Cell Movement / Q000502:physiology*; D002478:Cells, Cultured; D003110:Colonic Neoplasms / Q000201:enzymology / Q000378:metabolism* / Q000473:pathology; D004789:Enzyme Activation / Q000502:physiology; D045325:HCT116 Cells; D006801:Humans; D054594:Protein Tyrosine Phosphatase, Non-Receptor Type 12 / Q000502:physiology*; D051381:Rats; D020741:rho GTP-Binding Proteins / Q000037:antagonists & inhibitors* / Q000378:metabolism*
D054594:Protein Tyrosine Phosphatase, Non-Receptor Type 12; D020741:rho GTP-Binding Proteins