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Release of cAMP gating by the alpha6beta4 integrin stimulates lamellae formation and the chemotactic migration of invasive carcinoma cells.

O'Connor KL, Shaw LM, Mercurio AM - J. Cell Biol. (1998)

Bottom Line: Mercurio.Both lamellae formation and chemotactic migration are inhibited or "gated" by cAMP and our results reveal that a critical function of alpha6beta4 is to suppress the intracellular cAMP concentration by increasing the activity of a rolipram-sensitive, cAMP-specific phosphodiesterase (PDE).Although PI3-K and cAMP-specific PDE activities are both required to promote lamellae formation and chemotactic migration, our data indicate that they are components of distinct signaling pathways.

View Article: PubMed Central - PubMed

Affiliation: Department of Medicine, Beth Israel Deaconess Medical Center and Harvard Medical School, Boston, Massachusetts 02215, USA.

ABSTRACT
The alpha6beta4 integrin promotes carcinoma in-vasion by its activation of a phosphoinositide 3-OH (PI3-K) signaling pathway (Shaw, L.M., I. Rabinovitz, H.H.-F. Wang, A. Toker, and A.M. Mercurio. Cell. 91: 949-960). We demonstrate here using MDA-MB-435 breast carcinoma cells that alpha6beta4 stimulates chemotactic migration, a key component of invasion, but that it has no influence on haptotaxis. Stimulation of chemotaxis by alpha6beta4 expression was observed in response to either lysophosphatidic acid (LPA) or fibroblast conditioned medium. Moreover, the LPA-dependent formation of lamellae in these cells is dependent upon alpha6beta4 expression. Both lamellae formation and chemotactic migration are inhibited or "gated" by cAMP and our results reveal that a critical function of alpha6beta4 is to suppress the intracellular cAMP concentration by increasing the activity of a rolipram-sensitive, cAMP-specific phosphodiesterase (PDE). This PDE activity is essential for lamellae formation, chemotactic migration and invasion based on data obtained with PDE inhibitors. Although PI3-K and cAMP-specific PDE activities are both required to promote lamellae formation and chemotactic migration, our data indicate that they are components of distinct signaling pathways. The essence of our findings is that alpha6beta4 stimulates the chemotactic migration of carcinoma cells through its ability to influence key signaling events that underlie this critical component of carcinoma invasion.

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Lamellae formation in clone A colon carcinoma cells requires PDE  activity. Clone A colon carcinoma cells were either treated  with solvent alone (A and B)  or 1 mM IBMX in solvent (C  and D) and then plated on  laminin-1–coated coverslips.  After 45 min the cells were  fixed and stained for F-actin  using TRITC-phalloidin. (A  and C) Phase–contrast images; (B and D) fluorescence  images. Bar, 10 μm.
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Figure 9: Lamellae formation in clone A colon carcinoma cells requires PDE activity. Clone A colon carcinoma cells were either treated with solvent alone (A and B) or 1 mM IBMX in solvent (C and D) and then plated on laminin-1–coated coverslips. After 45 min the cells were fixed and stained for F-actin using TRITC-phalloidin. (A and C) Phase–contrast images; (B and D) fluorescence images. Bar, 10 μm.

Mentions: Recently, we reported that α6β4 is necessary for the formation and stabilization of lamellae in clone A colon carcinoma cells plated on laminin-1 (32). If PDE activity is needed for lamellae formation as indicated by the above results, IBMX should inhibit the formation of lamellae in clone A cells. To test this possibility, clone A cells were treated with IBMX or a solvent control and then plated onto laminin-1 for 45 min. The control cells formed large fan-shaped lamellae enriched in F-actin when plated on laminin-1 (Fig. 9, A and B) as we reported previously (32). In contrast, IBMX-treated cells formed small, immature lamellae with a marked reduction in F-actin content (Fig. 9, C and D). Quantitative analysis of these images revealed that IBMX reduced the total lamellar area of clone A cells on laminin-1 by ∼75% (629 ± 74 μm2 for control versus 164 ± 24μm2 with IBMX). Interestingly, inhibition of PDE activity had no effect on the attachment or spreading of clone A cells on laminin-1 (Fig. 9).


Release of cAMP gating by the alpha6beta4 integrin stimulates lamellae formation and the chemotactic migration of invasive carcinoma cells.

O'Connor KL, Shaw LM, Mercurio AM - J. Cell Biol. (1998)

Lamellae formation in clone A colon carcinoma cells requires PDE  activity. Clone A colon carcinoma cells were either treated  with solvent alone (A and B)  or 1 mM IBMX in solvent (C  and D) and then plated on  laminin-1–coated coverslips.  After 45 min the cells were  fixed and stained for F-actin  using TRITC-phalloidin. (A  and C) Phase–contrast images; (B and D) fluorescence  images. Bar, 10 μm.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC2132981&req=5

Figure 9: Lamellae formation in clone A colon carcinoma cells requires PDE activity. Clone A colon carcinoma cells were either treated with solvent alone (A and B) or 1 mM IBMX in solvent (C and D) and then plated on laminin-1–coated coverslips. After 45 min the cells were fixed and stained for F-actin using TRITC-phalloidin. (A and C) Phase–contrast images; (B and D) fluorescence images. Bar, 10 μm.
Mentions: Recently, we reported that α6β4 is necessary for the formation and stabilization of lamellae in clone A colon carcinoma cells plated on laminin-1 (32). If PDE activity is needed for lamellae formation as indicated by the above results, IBMX should inhibit the formation of lamellae in clone A cells. To test this possibility, clone A cells were treated with IBMX or a solvent control and then plated onto laminin-1 for 45 min. The control cells formed large fan-shaped lamellae enriched in F-actin when plated on laminin-1 (Fig. 9, A and B) as we reported previously (32). In contrast, IBMX-treated cells formed small, immature lamellae with a marked reduction in F-actin content (Fig. 9, C and D). Quantitative analysis of these images revealed that IBMX reduced the total lamellar area of clone A cells on laminin-1 by ∼75% (629 ± 74 μm2 for control versus 164 ± 24μm2 with IBMX). Interestingly, inhibition of PDE activity had no effect on the attachment or spreading of clone A cells on laminin-1 (Fig. 9).

Bottom Line: Mercurio.Both lamellae formation and chemotactic migration are inhibited or "gated" by cAMP and our results reveal that a critical function of alpha6beta4 is to suppress the intracellular cAMP concentration by increasing the activity of a rolipram-sensitive, cAMP-specific phosphodiesterase (PDE).Although PI3-K and cAMP-specific PDE activities are both required to promote lamellae formation and chemotactic migration, our data indicate that they are components of distinct signaling pathways.

View Article: PubMed Central - PubMed

Affiliation: Department of Medicine, Beth Israel Deaconess Medical Center and Harvard Medical School, Boston, Massachusetts 02215, USA.

ABSTRACT
The alpha6beta4 integrin promotes carcinoma in-vasion by its activation of a phosphoinositide 3-OH (PI3-K) signaling pathway (Shaw, L.M., I. Rabinovitz, H.H.-F. Wang, A. Toker, and A.M. Mercurio. Cell. 91: 949-960). We demonstrate here using MDA-MB-435 breast carcinoma cells that alpha6beta4 stimulates chemotactic migration, a key component of invasion, but that it has no influence on haptotaxis. Stimulation of chemotaxis by alpha6beta4 expression was observed in response to either lysophosphatidic acid (LPA) or fibroblast conditioned medium. Moreover, the LPA-dependent formation of lamellae in these cells is dependent upon alpha6beta4 expression. Both lamellae formation and chemotactic migration are inhibited or "gated" by cAMP and our results reveal that a critical function of alpha6beta4 is to suppress the intracellular cAMP concentration by increasing the activity of a rolipram-sensitive, cAMP-specific phosphodiesterase (PDE). This PDE activity is essential for lamellae formation, chemotactic migration and invasion based on data obtained with PDE inhibitors. Although PI3-K and cAMP-specific PDE activities are both required to promote lamellae formation and chemotactic migration, our data indicate that they are components of distinct signaling pathways. The essence of our findings is that alpha6beta4 stimulates the chemotactic migration of carcinoma cells through its ability to influence key signaling events that underlie this critical component of carcinoma invasion.

Show MeSH
Related in: MedlinePlus