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IGF-1 increases invasive potential of MCF 7 breast cancer cells and induces activation of latent TGF-β1 resulting in epithelial to mesenchymal transition.

Walsh LA, Damjanovski S - Cell Commun. Signal (2011)

Bottom Line: Furthermore, most studies describing the biological effects of TGF-β have been performed using high concentrations of active, soluble TGF-β, despite the fact that TGF-β is produced and secreted as a latent complex.The effects of IGF-1 appear to be mediated through signals transduced via the PI3K and MAPK pathways.In addition, increased IGF-1, together with latent TGF-β1 and active MMPs result in EMT.

View Article: PubMed Central - HTML - PubMed

Affiliation: Department of Biology, University of Western Ontario, London, Ontario, N6A 5B7, Canada. sdamjano@uwo.ca.

ABSTRACT

Introduction: TGF-β signaling has been extensively studied in many developmental contexts, amongst which is its ability to induce epithelial to mesenchymal transitions (EMT). EMTs play crucial roles during embryonic development and have also come under intense scrutiny as a mechanism through which breast cancers progress to become metastatic. Interestingly, while the molecular hallmarks of EMT progression (loss of cell adhesion, nuclear localization of β-catenin) are straightforward, the cellular signaling cascades that result in an EMT are numerous and diverse. Furthermore, most studies describing the biological effects of TGF-β have been performed using high concentrations of active, soluble TGF-β, despite the fact that TGF-β is produced and secreted as a latent complex.

Methods: MCF-7 breast cancer cells treated with recombinant IGF-1 were assayed for metalloproteinase activity and invasiveness through a matrigel coated transwell invasion chamber. IGF-1 treatments were then followed by the addition of latent-TGF-β1 to determine if elevated levels of IGF-1 together with latent-TGF-β1 could cause EMT.

Results: Results showed that IGF-1 - a molecule known to be elevated in breast cancer is a regulator of matrix metalloproteinase activity (MMP) and the invasive potential of MCF-7 breast cancer cells. The effects of IGF-1 appear to be mediated through signals transduced via the PI3K and MAPK pathways. In addition, increased IGF-1, together with latent TGF-β1 and active MMPs result in EMT.

Conclusions: Taken together our data suggest a novel a link between IGF-1 levels, MMP activity, TGF-β signaling, and EMT in breast cancer cells.

No MeSH data available.


Related in: MedlinePlus

Semi-quantitative real time PCR showed IGF-1 and latent TGF-β1 resulted in no changes in EMT marker gene expression consistent with EMT in Hs578t cells. Hs578t cells treated with (i) IGF-1, (ii) IGF-1+latent TGF-β1, (iii) IGF-1+latent TGF-β1+PI3K inhibitor, (iv) IGF-1+latent TGF-β1+MAPK inhibitor or (v) IGF-1+latent TGF-β1+TGF-β1 inhibitor were analyzed for levels of marker genes associated with EMT. Changes in N-cadherin, occludin, and vimentin expression were not consistent with EMT after treatment with IGF-1+TGF-β1 compared to TGF-β1 treatment alone. The addition of PI3K. MAPK or TGF-β1 inhibitors did not affect these changes in marker gene expression. Hs578t cells treated with TGF-β1 alone resulted in changes in marker gene expression that were also not consistent with EMT compared to vehicle control. All data are mean ± s.e.m. (n = 3, three experimental repeats).
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Figure 4: Semi-quantitative real time PCR showed IGF-1 and latent TGF-β1 resulted in no changes in EMT marker gene expression consistent with EMT in Hs578t cells. Hs578t cells treated with (i) IGF-1, (ii) IGF-1+latent TGF-β1, (iii) IGF-1+latent TGF-β1+PI3K inhibitor, (iv) IGF-1+latent TGF-β1+MAPK inhibitor or (v) IGF-1+latent TGF-β1+TGF-β1 inhibitor were analyzed for levels of marker genes associated with EMT. Changes in N-cadherin, occludin, and vimentin expression were not consistent with EMT after treatment with IGF-1+TGF-β1 compared to TGF-β1 treatment alone. The addition of PI3K. MAPK or TGF-β1 inhibitors did not affect these changes in marker gene expression. Hs578t cells treated with TGF-β1 alone resulted in changes in marker gene expression that were also not consistent with EMT compared to vehicle control. All data are mean ± s.e.m. (n = 3, three experimental repeats).

Mentions: To investigate the specificity of the IGF-1/latent TGF-β treatments in modulating EMT specific cellular events, a cell line that could not undergo an EMT was also used. In contrast to MCF-7 cells, Hs578t breast cancer cells are highly invasive atypical epithelial cells, do not express E-cadherin, and already have a mesenchymal morphology. Although treatment of Hs578t cells with IGF-1 and/or latent TGF-β1 resulted in minor alterations of EMT marker gene expression, there were no significant changes in multiple marker genes that would be consistent with, and indicative of an EMT signature (Figure 4) [17].


IGF-1 increases invasive potential of MCF 7 breast cancer cells and induces activation of latent TGF-β1 resulting in epithelial to mesenchymal transition.

Walsh LA, Damjanovski S - Cell Commun. Signal (2011)

Semi-quantitative real time PCR showed IGF-1 and latent TGF-β1 resulted in no changes in EMT marker gene expression consistent with EMT in Hs578t cells. Hs578t cells treated with (i) IGF-1, (ii) IGF-1+latent TGF-β1, (iii) IGF-1+latent TGF-β1+PI3K inhibitor, (iv) IGF-1+latent TGF-β1+MAPK inhibitor or (v) IGF-1+latent TGF-β1+TGF-β1 inhibitor were analyzed for levels of marker genes associated with EMT. Changes in N-cadherin, occludin, and vimentin expression were not consistent with EMT after treatment with IGF-1+TGF-β1 compared to TGF-β1 treatment alone. The addition of PI3K. MAPK or TGF-β1 inhibitors did not affect these changes in marker gene expression. Hs578t cells treated with TGF-β1 alone resulted in changes in marker gene expression that were also not consistent with EMT compared to vehicle control. All data are mean ± s.e.m. (n = 3, three experimental repeats).
© Copyright Policy - open-access
Related In: Results  -  Collection

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Show All Figures
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Figure 4: Semi-quantitative real time PCR showed IGF-1 and latent TGF-β1 resulted in no changes in EMT marker gene expression consistent with EMT in Hs578t cells. Hs578t cells treated with (i) IGF-1, (ii) IGF-1+latent TGF-β1, (iii) IGF-1+latent TGF-β1+PI3K inhibitor, (iv) IGF-1+latent TGF-β1+MAPK inhibitor or (v) IGF-1+latent TGF-β1+TGF-β1 inhibitor were analyzed for levels of marker genes associated with EMT. Changes in N-cadherin, occludin, and vimentin expression were not consistent with EMT after treatment with IGF-1+TGF-β1 compared to TGF-β1 treatment alone. The addition of PI3K. MAPK or TGF-β1 inhibitors did not affect these changes in marker gene expression. Hs578t cells treated with TGF-β1 alone resulted in changes in marker gene expression that were also not consistent with EMT compared to vehicle control. All data are mean ± s.e.m. (n = 3, three experimental repeats).
Mentions: To investigate the specificity of the IGF-1/latent TGF-β treatments in modulating EMT specific cellular events, a cell line that could not undergo an EMT was also used. In contrast to MCF-7 cells, Hs578t breast cancer cells are highly invasive atypical epithelial cells, do not express E-cadherin, and already have a mesenchymal morphology. Although treatment of Hs578t cells with IGF-1 and/or latent TGF-β1 resulted in minor alterations of EMT marker gene expression, there were no significant changes in multiple marker genes that would be consistent with, and indicative of an EMT signature (Figure 4) [17].

Bottom Line: Furthermore, most studies describing the biological effects of TGF-β have been performed using high concentrations of active, soluble TGF-β, despite the fact that TGF-β is produced and secreted as a latent complex.The effects of IGF-1 appear to be mediated through signals transduced via the PI3K and MAPK pathways.In addition, increased IGF-1, together with latent TGF-β1 and active MMPs result in EMT.

View Article: PubMed Central - HTML - PubMed

Affiliation: Department of Biology, University of Western Ontario, London, Ontario, N6A 5B7, Canada. sdamjano@uwo.ca.

ABSTRACT

Introduction: TGF-β signaling has been extensively studied in many developmental contexts, amongst which is its ability to induce epithelial to mesenchymal transitions (EMT). EMTs play crucial roles during embryonic development and have also come under intense scrutiny as a mechanism through which breast cancers progress to become metastatic. Interestingly, while the molecular hallmarks of EMT progression (loss of cell adhesion, nuclear localization of β-catenin) are straightforward, the cellular signaling cascades that result in an EMT are numerous and diverse. Furthermore, most studies describing the biological effects of TGF-β have been performed using high concentrations of active, soluble TGF-β, despite the fact that TGF-β is produced and secreted as a latent complex.

Methods: MCF-7 breast cancer cells treated with recombinant IGF-1 were assayed for metalloproteinase activity and invasiveness through a matrigel coated transwell invasion chamber. IGF-1 treatments were then followed by the addition of latent-TGF-β1 to determine if elevated levels of IGF-1 together with latent-TGF-β1 could cause EMT.

Results: Results showed that IGF-1 - a molecule known to be elevated in breast cancer is a regulator of matrix metalloproteinase activity (MMP) and the invasive potential of MCF-7 breast cancer cells. The effects of IGF-1 appear to be mediated through signals transduced via the PI3K and MAPK pathways. In addition, increased IGF-1, together with latent TGF-β1 and active MMPs result in EMT.

Conclusions: Taken together our data suggest a novel a link between IGF-1 levels, MMP activity, TGF-β signaling, and EMT in breast cancer cells.

No MeSH data available.


Related in: MedlinePlus