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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

Src is an important mediator of FAK-regulated apoptosis in T24 bladder cancer cells. T24 bladder cancer cells were treated with PP2. (A and B) Cell apoptosis was examined using (A) deoxynucleotidyl transferase-mediated dUTP-biotin nick end labeling assay and (B) Annexin V/propidium iodide. (C and D) The expression of FAK, pFAK, Src and pSrc was examined using western blotting. Scale bar, 200 µm. FAK, focal adhesion kinase; pFAK, phosphorylated FAK; TGFβ, transforming growth factor-β.
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f3-etm-0-0-2745: Src is an important mediator of FAK-regulated apoptosis in T24 bladder cancer cells. T24 bladder cancer cells were treated with PP2. (A and B) Cell apoptosis was examined using (A) deoxynucleotidyl transferase-mediated dUTP-biotin nick end labeling assay and (B) Annexin V/propidium iodide. (C and D) The expression of FAK, pFAK, Src and pSrc was examined using western blotting. Scale bar, 200 µm. FAK, focal adhesion kinase; pFAK, phosphorylated FAK; TGFβ, transforming growth factor-β.

Mentions: FAK is a substrate for the oncogene protein tyrosine kinase Src (21). To further whether the inhibition of Src phosphorylation could also promote the apoptosis of T24 bladder cancer cells, PP2, a selective inhibitor of Src, was employed to inhibit the TGFβ-induced phosphorylation of Src. The results of the TUNEL (Fig. 3A) and Annexin V/PI (Fig. 3B) assays showed that PP2, similarly to the FAK inhibitor PF-228, was able to induce the apoptosis of T24 bladder cancer cells. The western blotting results demonstrated that PP2 significantly reduced the TGFβ-induced phosphorylation of not only Src but also FAK (Fig. 3C and D).


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)

Src is an important mediator of FAK-regulated apoptosis in T24 bladder cancer cells. T24 bladder cancer cells were treated with PP2. (A and B) Cell apoptosis was examined using (A) deoxynucleotidyl transferase-mediated dUTP-biotin nick end labeling assay and (B) Annexin V/propidium iodide. (C and D) The expression of FAK, pFAK, Src and pSrc was examined using western blotting. Scale bar, 200 µm. FAK, focal adhesion kinase; pFAK, phosphorylated FAK; TGFβ, transforming growth factor-β.
© Copyright Policy - open-access
Related In: Results  -  Collection

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

f3-etm-0-0-2745: Src is an important mediator of FAK-regulated apoptosis in T24 bladder cancer cells. T24 bladder cancer cells were treated with PP2. (A and B) Cell apoptosis was examined using (A) deoxynucleotidyl transferase-mediated dUTP-biotin nick end labeling assay and (B) Annexin V/propidium iodide. (C and D) The expression of FAK, pFAK, Src and pSrc was examined using western blotting. Scale bar, 200 µm. FAK, focal adhesion kinase; pFAK, phosphorylated FAK; TGFβ, transforming growth factor-β.
Mentions: FAK is a substrate for the oncogene protein tyrosine kinase Src (21). To further whether the inhibition of Src phosphorylation could also promote the apoptosis of T24 bladder cancer cells, PP2, a selective inhibitor of Src, was employed to inhibit the TGFβ-induced phosphorylation of Src. The results of the TUNEL (Fig. 3A) and Annexin V/PI (Fig. 3B) assays showed that PP2, similarly to the FAK inhibitor PF-228, was able to induce the apoptosis of T24 bladder cancer cells. The western blotting results demonstrated that PP2 significantly reduced the TGFβ-induced phosphorylation of not only Src but also FAK (Fig. 3C and D).

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