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Inhibition of focal adhesion kinase induces apoptosis in bladder cancer cells via Src and the phosphatidylinositol 3-kinase/Akt pathway.

Kong D, Chen F, Sima NI - Exp Ther Med (2015)

Bottom Line: It was found that both the knockdown of FAK and the suppression of FAK phosphorylation were able to induce apoptosis in bladder cancer cells.Conversely, the expression of neither the general nor the tyrosine-phosphorylated FAK was regulated by inhibiting PI3K/Akt, which suggested that PI3K/Akt acted downstream of FAK to regulate apoptosis in bladder cancer cells.FAK may function as an important regulator of extracellular signaling-mediated apoptosis in bladder cancer and be used as a novel therapeutic target in the treatment of the condition.

View Article: PubMed Central - PubMed

Affiliation: Department of Urology, The First Affiliated Hospital, School of Medicine, Zhejiang University, Hangzhou, Zhejiang 310003, P.R. China.

ABSTRACT

Focal adhesion kinase (FAK) is a 125-kDa, cytosolic, non-receptor, protein tyrosine kinase localized at focal adhesions that can be activated by multiple inputs and in different manners. FAK is implicated in signaling pathways regulating cell movement, invasion, survival, gene expression and cancer stem cell self-renewal. The aim of the present study was to investigate whether FAK plays a role in the apoptosis of bladder cancer cells. The study employed in situ deoxynucleotidyl transferase-mediated dUTP-biotin nick end labeling and Annexin V labeling flow cytometry. It was found that both the knockdown of FAK and the suppression of FAK phosphorylation were able to induce apoptosis in bladder cancer cells. Caspase-3 was activated during the apoptosis induced by the suppression of FAK phosphorylation. Src was involved in FAK-regulated apoptosis in bladder cancer cells, while the suppression of Src phosphorylation was able to inhibit FAK tyrosine phosphorylation and induce apoptosis. Furthermore, phosphatidylinositol 3-kinase (PI3K)/Akt signaling was inhibited via the suppression of FAK tyrosine phosphorylation. Conversely, the expression of neither the general nor the tyrosine-phosphorylated FAK was regulated by inhibiting PI3K/Akt, which suggested that PI3K/Akt acted downstream of FAK to regulate apoptosis in bladder cancer cells. These findings indicate the presence of a mechanism of apoptosis involving FAK-mediated oncogenic signaling. FAK may function as an important regulator of extracellular signaling-mediated apoptosis in bladder cancer and be used as a novel therapeutic target in the treatment of the condition.

No MeSH data available.


Related in: MedlinePlus

Phosphatidylinositol 3-kinase/Akt acts downstream of FAK signaling to regulate apoptosis in T24 bladder cancer cells. T24 bladder cancer cells were treated with LY294002. (A and B) The expression of Akt, pAkt, caspase-3 and c-caspase-3 was examined using western blotting. (C and D) Cell apoptosis was examined using (C) deoxynucleotidyl transferase-mediated dUTP-biotin nick end labeling assay and (D) Annexin V/propidium iodide. (E and F) The expression of FAK and pFAK was examined using western blotting. Scale bar, 200 µm. FAK, focal adhesion kinase; pFAK, phosphorylated FAK; c-caspase-3, cleaved caspase-3; TGFβ, transforming growth factor-β.
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f4-etm-0-0-2745: Phosphatidylinositol 3-kinase/Akt acts downstream of FAK signaling to regulate apoptosis in T24 bladder cancer cells. T24 bladder cancer cells were treated with LY294002. (A and B) The expression of Akt, pAkt, caspase-3 and c-caspase-3 was examined using western blotting. (C and D) Cell apoptosis was examined using (C) deoxynucleotidyl transferase-mediated dUTP-biotin nick end labeling assay and (D) Annexin V/propidium iodide. (E and F) The expression of FAK and pFAK was examined using western blotting. Scale bar, 200 µm. FAK, focal adhesion kinase; pFAK, phosphorylated FAK; c-caspase-3, cleaved caspase-3; TGFβ, transforming growth factor-β.

Mentions: PI3K/Akt is a potent pathway of survival and apoptosis (22), and FAK is believed to be an upstream signal protein of the PI3K/Akt pathway (23); therefore, it was investigated whether PI3K/Akt acted downstream of FAK to regulate the apoptosis of T24 bladder cancer cells. Western blot analysis showed that Akt and FAK phosphorylation was suppressed by PF-228 (Fig. 2C and D). In addition, LY294002 significantly downregulated pAkt in the T24 cells (Fig. 4A and B). The results of the TUNEL (Fig. 4C) and Annexin V/PI (Fig. 4D) assays showed that LY294002 was able to induce the apoptosis of T24 cells. Conversely, the expression of general and tyrosine-phosphorylated FAK was not regulated by inhibiting PI3K/Akt in T24 cells (Fig. 4E and F).


Inhibition of focal adhesion kinase induces apoptosis in bladder cancer cells via Src and the phosphatidylinositol 3-kinase/Akt pathway.

Kong D, Chen F, Sima NI - Exp Ther Med (2015)

Phosphatidylinositol 3-kinase/Akt acts downstream of FAK signaling to regulate apoptosis in T24 bladder cancer cells. T24 bladder cancer cells were treated with LY294002. (A and B) The expression of Akt, pAkt, caspase-3 and c-caspase-3 was examined using western blotting. (C and D) Cell apoptosis was examined using (C) deoxynucleotidyl transferase-mediated dUTP-biotin nick end labeling assay and (D) Annexin V/propidium iodide. (E and F) The expression of FAK and pFAK was examined using western blotting. Scale bar, 200 µm. FAK, focal adhesion kinase; pFAK, phosphorylated FAK; c-caspase-3, cleaved caspase-3; TGFβ, transforming growth factor-β.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4665970&req=5

f4-etm-0-0-2745: Phosphatidylinositol 3-kinase/Akt acts downstream of FAK signaling to regulate apoptosis in T24 bladder cancer cells. T24 bladder cancer cells were treated with LY294002. (A and B) The expression of Akt, pAkt, caspase-3 and c-caspase-3 was examined using western blotting. (C and D) Cell apoptosis was examined using (C) deoxynucleotidyl transferase-mediated dUTP-biotin nick end labeling assay and (D) Annexin V/propidium iodide. (E and F) The expression of FAK and pFAK was examined using western blotting. Scale bar, 200 µm. FAK, focal adhesion kinase; pFAK, phosphorylated FAK; c-caspase-3, cleaved caspase-3; TGFβ, transforming growth factor-β.
Mentions: PI3K/Akt is a potent pathway of survival and apoptosis (22), and FAK is believed to be an upstream signal protein of the PI3K/Akt pathway (23); therefore, it was investigated whether PI3K/Akt acted downstream of FAK to regulate the apoptosis of T24 bladder cancer cells. Western blot analysis showed that Akt and FAK phosphorylation was suppressed by PF-228 (Fig. 2C and D). In addition, LY294002 significantly downregulated pAkt in the T24 cells (Fig. 4A and B). The results of the TUNEL (Fig. 4C) and Annexin V/PI (Fig. 4D) assays showed that LY294002 was able to induce the apoptosis of T24 cells. Conversely, the expression of general and tyrosine-phosphorylated FAK was not regulated by inhibiting PI3K/Akt in T24 cells (Fig. 4E and F).

Bottom Line: It was found that both the knockdown of FAK and the suppression of FAK phosphorylation were able to induce apoptosis in bladder cancer cells.Conversely, the expression of neither the general nor the tyrosine-phosphorylated FAK was regulated by inhibiting PI3K/Akt, which suggested that PI3K/Akt acted downstream of FAK to regulate apoptosis in bladder cancer cells.FAK may function as an important regulator of extracellular signaling-mediated apoptosis in bladder cancer and be used as a novel therapeutic target in the treatment of the condition.

View Article: PubMed Central - PubMed

Affiliation: Department of Urology, The First Affiliated Hospital, School of Medicine, Zhejiang University, Hangzhou, Zhejiang 310003, P.R. China.

ABSTRACT

Focal adhesion kinase (FAK) is a 125-kDa, cytosolic, non-receptor, protein tyrosine kinase localized at focal adhesions that can be activated by multiple inputs and in different manners. FAK is implicated in signaling pathways regulating cell movement, invasion, survival, gene expression and cancer stem cell self-renewal. The aim of the present study was to investigate whether FAK plays a role in the apoptosis of bladder cancer cells. The study employed in situ deoxynucleotidyl transferase-mediated dUTP-biotin nick end labeling and Annexin V labeling flow cytometry. It was found that both the knockdown of FAK and the suppression of FAK phosphorylation were able to induce apoptosis in bladder cancer cells. Caspase-3 was activated during the apoptosis induced by the suppression of FAK phosphorylation. Src was involved in FAK-regulated apoptosis in bladder cancer cells, while the suppression of Src phosphorylation was able to inhibit FAK tyrosine phosphorylation and induce apoptosis. Furthermore, phosphatidylinositol 3-kinase (PI3K)/Akt signaling was inhibited via the suppression of FAK tyrosine phosphorylation. Conversely, the expression of neither the general nor the tyrosine-phosphorylated FAK was regulated by inhibiting PI3K/Akt, which suggested that PI3K/Akt acted downstream of FAK to regulate apoptosis in bladder cancer cells. These findings indicate the presence of a mechanism of apoptosis involving FAK-mediated oncogenic signaling. FAK may function as an important regulator of extracellular signaling-mediated apoptosis in bladder cancer and be used as a novel therapeutic target in the treatment of the condition.

No MeSH data available.


Related in: MedlinePlus