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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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cAMP specific-PDE activity is required for LPA-dependent formation of lamellae in the MDA/β4 transfectants. The  MDA/β4 transfectants (5B3) were plated on collagen I–coated  coverslips. After 2 h, the cells were either left untreated (A and  C) or treated with 1mM IBMX (B and D) for 30 min. Subsequently, the cells were either left untreated (A and B) or treated  with 100 nM LPA for 5 min (C and D). The cells were then fixed  and visualized using Nomarski DIC optics. (E) The effect of LPA  and IBMX on lamellar area was quantified using IPLab Spectrum  imaging software. Bars represent mean lamellar area ± standard  error in which n > 20. Of note, IBMX inhibited the LPA-dependent formation of lamellae by 70%.
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Figure 8: cAMP specific-PDE activity is required for LPA-dependent formation of lamellae in the MDA/β4 transfectants. The MDA/β4 transfectants (5B3) were plated on collagen I–coated coverslips. After 2 h, the cells were either left untreated (A and C) or treated with 1mM IBMX (B and D) for 30 min. Subsequently, the cells were either left untreated (A and B) or treated with 100 nM LPA for 5 min (C and D). The cells were then fixed and visualized using Nomarski DIC optics. (E) The effect of LPA and IBMX on lamellar area was quantified using IPLab Spectrum imaging software. Bars represent mean lamellar area ± standard error in which n > 20. Of note, IBMX inhibited the LPA-dependent formation of lamellae by 70%.

Mentions: The necessity of cAMP-specific PDE activity in the formation of lamellae was also assessed. IBMX had no effect on the morphology of the MDA/β4 transfectants in the absence of LPA (Fig. 8, compare A with B). However, IBMX-treated cells were unable to form the large, ruffling lamellae in response to LPA stimulation in comparison to untreated cells (Fig. 8, compare C with D). Quantitative analysis of these cell populations revealed that inhibition of PDE activity resulted in an approximate fourfold reduction in the lamellar area of LPA-stimulated MDA/β4 transfectants (Fig. 8 E).


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)

cAMP specific-PDE activity is required for LPA-dependent formation of lamellae in the MDA/β4 transfectants. The  MDA/β4 transfectants (5B3) were plated on collagen I–coated  coverslips. After 2 h, the cells were either left untreated (A and  C) or treated with 1mM IBMX (B and D) for 30 min. Subsequently, the cells were either left untreated (A and B) or treated  with 100 nM LPA for 5 min (C and D). The cells were then fixed  and visualized using Nomarski DIC optics. (E) The effect of LPA  and IBMX on lamellar area was quantified using IPLab Spectrum  imaging software. Bars represent mean lamellar area ± standard  error in which n > 20. Of note, IBMX inhibited the LPA-dependent formation of lamellae by 70%.
© Copyright Policy
Related In: Results  -  Collection

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

Figure 8: cAMP specific-PDE activity is required for LPA-dependent formation of lamellae in the MDA/β4 transfectants. The MDA/β4 transfectants (5B3) were plated on collagen I–coated coverslips. After 2 h, the cells were either left untreated (A and C) or treated with 1mM IBMX (B and D) for 30 min. Subsequently, the cells were either left untreated (A and B) or treated with 100 nM LPA for 5 min (C and D). The cells were then fixed and visualized using Nomarski DIC optics. (E) The effect of LPA and IBMX on lamellar area was quantified using IPLab Spectrum imaging software. Bars represent mean lamellar area ± standard error in which n > 20. Of note, IBMX inhibited the LPA-dependent formation of lamellae by 70%.
Mentions: The necessity of cAMP-specific PDE activity in the formation of lamellae was also assessed. IBMX had no effect on the morphology of the MDA/β4 transfectants in the absence of LPA (Fig. 8, compare A with B). However, IBMX-treated cells were unable to form the large, ruffling lamellae in response to LPA stimulation in comparison to untreated cells (Fig. 8, compare C with D). Quantitative analysis of these cell populations revealed that inhibition of PDE activity resulted in an approximate fourfold reduction in the lamellar area of LPA-stimulated MDA/β4 transfectants (Fig. 8 E).

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