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p63 promotes cell survival through fatty acid synthase.

Sabbisetti V, Di Napoli A, Seeley A, Amato AM, O'Regan E, Ghebremichael M, Loda M, Signoretti S - PLoS ONE (2009)

Bottom Line: Here we show that knockdown of either total or DeltaN-specific p63 isoforms in squamous cell carcinoma (SCC9) or immortalized prostate epithelial (iPrEC) cells caused a decrease in cell viability by inducing apoptosis without affecting the cell cycle. p63 silencing significantly reduced both the expression and the activity of FASN.FASN induced AKT phosphorylation and a significant reduction in cell viability was observed when FASN-overexpressing SCC9 cells were treated with an AKT inhibitor after p63 knockdown, indicating that AKT plays a major role in FASN-mediated survival.Taken together, our findings demonstrate that FASN is a functionally relevant target of p63 and is required for mediating its pro-survival effects.

View Article: PubMed Central - PubMed

Affiliation: Department of Pathology, Brigham and Women's Hospital, Dana-Farber Cancer Institute, Harvard Medical School, Boston, MA, USA.

ABSTRACT
There is increasing evidence that p63, and specifically DeltaNp63, plays a central role in both development and tumorigenesis by promoting epithelial cell survival. However, few studies have addressed the molecular mechanisms through which such important function is exerted. Fatty acid synthase (FASN), a key enzyme that synthesizes long-chain fatty acids and is involved in both embryogenesis and cancer, has been recently proposed as a direct target of p53 family members, including p63 and p73. Here we show that knockdown of either total or DeltaN-specific p63 isoforms in squamous cell carcinoma (SCC9) or immortalized prostate epithelial (iPrEC) cells caused a decrease in cell viability by inducing apoptosis without affecting the cell cycle. p63 silencing significantly reduced both the expression and the activity of FASN. Importantly, stable overexpression of either FASN or myristoylated AKT (myr-AKT) was able to partially rescue cells from cell death induced by p63 silencing. FASN induced AKT phosphorylation and a significant reduction in cell viability was observed when FASN-overexpressing SCC9 cells were treated with an AKT inhibitor after p63 knockdown, indicating that AKT plays a major role in FASN-mediated survival. Activated AKT did not cause any alteration in the FASN protein levels but induced its activity, suggesting that the rescue from apoptosis documented in the p63-silenced cells expressing myr-AKT cells may be partially mediated by FASN. Finally, we demonstrated that p63 and FASN expression are positively associated in clinical squamous cell carcinoma samples as well as in the developing prostate. Taken together, our findings demonstrate that FASN is a functionally relevant target of p63 and is required for mediating its pro-survival effects.

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p63 silencing induces a decrease in AKT phosphorylation.Immunoblot analysis of total AKT, phospho-AKT (Ser 473), and phospho-S6 (Ser 235/236) in SCC9 cells transfected with Tp63, Dp63 or Scr siRNAs (left panel), in SCC9-Tp63 cells with or without treatment with tetracycline (middle panel) and in iPrEC-Tp63 cells with or without treatment with tetracycline (right panel).
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pone-0005877-g004: p63 silencing induces a decrease in AKT phosphorylation.Immunoblot analysis of total AKT, phospho-AKT (Ser 473), and phospho-S6 (Ser 235/236) in SCC9 cells transfected with Tp63, Dp63 or Scr siRNAs (left panel), in SCC9-Tp63 cells with or without treatment with tetracycline (middle panel) and in iPrEC-Tp63 cells with or without treatment with tetracycline (right panel).

Mentions: Phosphatidylinositol-3′-kinase (PI-3′K)/protein kinase B (AKT) signaling has been extensively implicated in cell survival and there is some evidence that AKT might function both upstream and downstream of FASN [37]. Therefore, we also analyzed the role of p63 in modulating AKT activation in both transformed and immortalized epithelial cells. Silencing of p63 in both SCC9 and iPrEC cells induced a significant decrease in the phosphorylation of AKT without causing any changes in total AKT levels (Figure 4). In addition, we observed that p63 silencing resulted in a decrease in phosphorylation of ribosomal protein S6, which is a downstream effector of the PI-3K-AKT pathway.


p63 promotes cell survival through fatty acid synthase.

Sabbisetti V, Di Napoli A, Seeley A, Amato AM, O'Regan E, Ghebremichael M, Loda M, Signoretti S - PLoS ONE (2009)

p63 silencing induces a decrease in AKT phosphorylation.Immunoblot analysis of total AKT, phospho-AKT (Ser 473), and phospho-S6 (Ser 235/236) in SCC9 cells transfected with Tp63, Dp63 or Scr siRNAs (left panel), in SCC9-Tp63 cells with or without treatment with tetracycline (middle panel) and in iPrEC-Tp63 cells with or without treatment with tetracycline (right panel).
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC2691576&req=5

pone-0005877-g004: p63 silencing induces a decrease in AKT phosphorylation.Immunoblot analysis of total AKT, phospho-AKT (Ser 473), and phospho-S6 (Ser 235/236) in SCC9 cells transfected with Tp63, Dp63 or Scr siRNAs (left panel), in SCC9-Tp63 cells with or without treatment with tetracycline (middle panel) and in iPrEC-Tp63 cells with or without treatment with tetracycline (right panel).
Mentions: Phosphatidylinositol-3′-kinase (PI-3′K)/protein kinase B (AKT) signaling has been extensively implicated in cell survival and there is some evidence that AKT might function both upstream and downstream of FASN [37]. Therefore, we also analyzed the role of p63 in modulating AKT activation in both transformed and immortalized epithelial cells. Silencing of p63 in both SCC9 and iPrEC cells induced a significant decrease in the phosphorylation of AKT without causing any changes in total AKT levels (Figure 4). In addition, we observed that p63 silencing resulted in a decrease in phosphorylation of ribosomal protein S6, which is a downstream effector of the PI-3K-AKT pathway.

Bottom Line: Here we show that knockdown of either total or DeltaN-specific p63 isoforms in squamous cell carcinoma (SCC9) or immortalized prostate epithelial (iPrEC) cells caused a decrease in cell viability by inducing apoptosis without affecting the cell cycle. p63 silencing significantly reduced both the expression and the activity of FASN.FASN induced AKT phosphorylation and a significant reduction in cell viability was observed when FASN-overexpressing SCC9 cells were treated with an AKT inhibitor after p63 knockdown, indicating that AKT plays a major role in FASN-mediated survival.Taken together, our findings demonstrate that FASN is a functionally relevant target of p63 and is required for mediating its pro-survival effects.

View Article: PubMed Central - PubMed

Affiliation: Department of Pathology, Brigham and Women's Hospital, Dana-Farber Cancer Institute, Harvard Medical School, Boston, MA, USA.

ABSTRACT
There is increasing evidence that p63, and specifically DeltaNp63, plays a central role in both development and tumorigenesis by promoting epithelial cell survival. However, few studies have addressed the molecular mechanisms through which such important function is exerted. Fatty acid synthase (FASN), a key enzyme that synthesizes long-chain fatty acids and is involved in both embryogenesis and cancer, has been recently proposed as a direct target of p53 family members, including p63 and p73. Here we show that knockdown of either total or DeltaN-specific p63 isoforms in squamous cell carcinoma (SCC9) or immortalized prostate epithelial (iPrEC) cells caused a decrease in cell viability by inducing apoptosis without affecting the cell cycle. p63 silencing significantly reduced both the expression and the activity of FASN. Importantly, stable overexpression of either FASN or myristoylated AKT (myr-AKT) was able to partially rescue cells from cell death induced by p63 silencing. FASN induced AKT phosphorylation and a significant reduction in cell viability was observed when FASN-overexpressing SCC9 cells were treated with an AKT inhibitor after p63 knockdown, indicating that AKT plays a major role in FASN-mediated survival. Activated AKT did not cause any alteration in the FASN protein levels but induced its activity, suggesting that the rescue from apoptosis documented in the p63-silenced cells expressing myr-AKT cells may be partially mediated by FASN. Finally, we demonstrated that p63 and FASN expression are positively associated in clinical squamous cell carcinoma samples as well as in the developing prostate. Taken together, our findings demonstrate that FASN is a functionally relevant target of p63 and is required for mediating its pro-survival effects.

Show MeSH
Related in: MedlinePlus