Limits...
TGFβ-induced invasion of prostate cancer cells is promoted by c-Jun-dependent transcriptional activation of Snail1.

Thakur N, Gudey SK, Marcusson A, Fu JY, Bergh A, Heldin CH, Landström M - Cell Cycle (2014)

Bottom Line: In this study, we have identified a novel binding site for c-Jun in the promoter of the Snail1 gene and report that the activation of the TGFβ-TRAF6-p38 MAPK pathway promotes both c-Jun expression and its activation via p38α-dependent phosphorylation of c-Jun at Ser63.The TRAF6-dependent activation of p38 also leads to increased stability of c-Jun, due to p38-dependent inactivation of glycogen synthase kinase (GSK) 3β by phosphorylation at Ser9.Thus, our findings elucidate a novel role for the p38 MAPK pathway in stimulated cells, leading to activation of c-Jun and its binding to the promoter of Snail1, thereby triggering motility and invasiveness of aggressive human prostate cancer cells.

View Article: PubMed Central - PubMed

Affiliation: a Ludwig Institute for Cancer Research; Science for Life Laboratory; Uppsala University; Uppsala, Sweden.

ABSTRACT
High levels of transforming growth factor-β (TGFβ) correlate with poor prognosis for patients with prostate cancer and other cancers. TGFβ is a multifunctional cytokine and crucial regulator of cell fate, such as epithelial to mesenchymal transition (EMT), which is implicated in cancer invasion and progression. TGFβ conveys its signals upon binding to type I and type II serine/threonine kinase receptors (TβRI/II); phosphorylation of Smad2 and Smad3 promotes their association with Smad4, which regulates expression of targets genes, such as Smad7, p21, and c-Jun. TGFβ also activates the ubiquitin ligase tumor necrosis factor receptor-associated factor 6 (TRAF6), which associates with TβRI and activates the p38 mitogen-activated protein kinase (MAPK) pathway. Snail1 is a key transcription factor, induced by TGFβ that promotes migration and invasion of cancer cells. In this study, we have identified a novel binding site for c-Jun in the promoter of the Snail1 gene and report that the activation of the TGFβ-TRAF6-p38 MAPK pathway promotes both c-Jun expression and its activation via p38α-dependent phosphorylation of c-Jun at Ser63. The TRAF6-dependent activation of p38 also leads to increased stability of c-Jun, due to p38-dependent inactivation of glycogen synthase kinase (GSK) 3β by phosphorylation at Ser9. Thus, our findings elucidate a novel role for the p38 MAPK pathway in stimulated cells, leading to activation of c-Jun and its binding to the promoter of Snail1, thereby triggering motility and invasiveness of aggressive human prostate cancer cells.

Show MeSH

Related in: MedlinePlus

Figure 7. p38α is required for TGFβ-induced c-Jun activation. (A) PC-3U cells were transiently transfected with control (CTRL) or p38α (p38) siRNA treated or not with TGFβ for 30 min, and then subjected to a cell culture wound healing assay. Thereafter, the cells were fixed and subjected to co-immunofluorescence stainings for p-p38 (red) and p-Ser63 c-Jun (Scale bar 20 μM). (B) The activation status of c-Jun was analyzed in PC-3U cells transiently transfected with control (CTRL) or p38α (p38) siRNA, treated with or without TGFβ for indicated time periods. The cells were lysed and subjected to immunoblotting using p-Ser63-c-Jun, total c-Jun and p38α antibodies. Actin served as internal control.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
getmorefigures.php?uid=PMC4128885&req=5

Figure 7: Figure 7. p38α is required for TGFβ-induced c-Jun activation. (A) PC-3U cells were transiently transfected with control (CTRL) or p38α (p38) siRNA treated or not with TGFβ for 30 min, and then subjected to a cell culture wound healing assay. Thereafter, the cells were fixed and subjected to co-immunofluorescence stainings for p-p38 (red) and p-Ser63 c-Jun (Scale bar 20 μM). (B) The activation status of c-Jun was analyzed in PC-3U cells transiently transfected with control (CTRL) or p38α (p38) siRNA, treated with or without TGFβ for indicated time periods. The cells were lysed and subjected to immunoblotting using p-Ser63-c-Jun, total c-Jun and p38α antibodies. Actin served as internal control.

Mentions: To further explore the p38-c-Jun pathway, we investigated whether p38 and c-Jun co-localize in the nuclei of PC-3U cells upon stimulation with TGFβ. Active p38 was found to be co-localized with p-c-Jun Ser63 in the nucleus of TGFβ-stimulated cells (Fig. 7A), while neither active p38 nor c-Jun was detected in PC-3U cells treated with p38α siRNA, consistent with our previous observations of a p38-induced phosphorylation of c-Jun. Knock-down of p38α prevented TGFβ-induced activation of c-Jun, by phosphorylation of c-Jun at Ser63, as well as increase of total c-Jun, as demonstrated by immunoblotting (Fig. 7B). These observations support the notion that p38α phosphorylates and activates c-Jun in response to TGFβ in PC-3U cells.


TGFβ-induced invasion of prostate cancer cells is promoted by c-Jun-dependent transcriptional activation of Snail1.

Thakur N, Gudey SK, Marcusson A, Fu JY, Bergh A, Heldin CH, Landström M - Cell Cycle (2014)

Figure 7. p38α is required for TGFβ-induced c-Jun activation. (A) PC-3U cells were transiently transfected with control (CTRL) or p38α (p38) siRNA treated or not with TGFβ for 30 min, and then subjected to a cell culture wound healing assay. Thereafter, the cells were fixed and subjected to co-immunofluorescence stainings for p-p38 (red) and p-Ser63 c-Jun (Scale bar 20 μM). (B) The activation status of c-Jun was analyzed in PC-3U cells transiently transfected with control (CTRL) or p38α (p38) siRNA, treated with or without TGFβ for indicated time periods. The cells were lysed and subjected to immunoblotting using p-Ser63-c-Jun, total c-Jun and p38α antibodies. Actin served as internal control.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4128885&req=5

Figure 7: Figure 7. p38α is required for TGFβ-induced c-Jun activation. (A) PC-3U cells were transiently transfected with control (CTRL) or p38α (p38) siRNA treated or not with TGFβ for 30 min, and then subjected to a cell culture wound healing assay. Thereafter, the cells were fixed and subjected to co-immunofluorescence stainings for p-p38 (red) and p-Ser63 c-Jun (Scale bar 20 μM). (B) The activation status of c-Jun was analyzed in PC-3U cells transiently transfected with control (CTRL) or p38α (p38) siRNA, treated with or without TGFβ for indicated time periods. The cells were lysed and subjected to immunoblotting using p-Ser63-c-Jun, total c-Jun and p38α antibodies. Actin served as internal control.
Mentions: To further explore the p38-c-Jun pathway, we investigated whether p38 and c-Jun co-localize in the nuclei of PC-3U cells upon stimulation with TGFβ. Active p38 was found to be co-localized with p-c-Jun Ser63 in the nucleus of TGFβ-stimulated cells (Fig. 7A), while neither active p38 nor c-Jun was detected in PC-3U cells treated with p38α siRNA, consistent with our previous observations of a p38-induced phosphorylation of c-Jun. Knock-down of p38α prevented TGFβ-induced activation of c-Jun, by phosphorylation of c-Jun at Ser63, as well as increase of total c-Jun, as demonstrated by immunoblotting (Fig. 7B). These observations support the notion that p38α phosphorylates and activates c-Jun in response to TGFβ in PC-3U cells.

Bottom Line: In this study, we have identified a novel binding site for c-Jun in the promoter of the Snail1 gene and report that the activation of the TGFβ-TRAF6-p38 MAPK pathway promotes both c-Jun expression and its activation via p38α-dependent phosphorylation of c-Jun at Ser63.The TRAF6-dependent activation of p38 also leads to increased stability of c-Jun, due to p38-dependent inactivation of glycogen synthase kinase (GSK) 3β by phosphorylation at Ser9.Thus, our findings elucidate a novel role for the p38 MAPK pathway in stimulated cells, leading to activation of c-Jun and its binding to the promoter of Snail1, thereby triggering motility and invasiveness of aggressive human prostate cancer cells.

View Article: PubMed Central - PubMed

Affiliation: a Ludwig Institute for Cancer Research; Science for Life Laboratory; Uppsala University; Uppsala, Sweden.

ABSTRACT
High levels of transforming growth factor-β (TGFβ) correlate with poor prognosis for patients with prostate cancer and other cancers. TGFβ is a multifunctional cytokine and crucial regulator of cell fate, such as epithelial to mesenchymal transition (EMT), which is implicated in cancer invasion and progression. TGFβ conveys its signals upon binding to type I and type II serine/threonine kinase receptors (TβRI/II); phosphorylation of Smad2 and Smad3 promotes their association with Smad4, which regulates expression of targets genes, such as Smad7, p21, and c-Jun. TGFβ also activates the ubiquitin ligase tumor necrosis factor receptor-associated factor 6 (TRAF6), which associates with TβRI and activates the p38 mitogen-activated protein kinase (MAPK) pathway. Snail1 is a key transcription factor, induced by TGFβ that promotes migration and invasion of cancer cells. In this study, we have identified a novel binding site for c-Jun in the promoter of the Snail1 gene and report that the activation of the TGFβ-TRAF6-p38 MAPK pathway promotes both c-Jun expression and its activation via p38α-dependent phosphorylation of c-Jun at Ser63. The TRAF6-dependent activation of p38 also leads to increased stability of c-Jun, due to p38-dependent inactivation of glycogen synthase kinase (GSK) 3β by phosphorylation at Ser9. Thus, our findings elucidate a novel role for the p38 MAPK pathway in stimulated cells, leading to activation of c-Jun and its binding to the promoter of Snail1, thereby triggering motility and invasiveness of aggressive human prostate cancer cells.

Show MeSH
Related in: MedlinePlus