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Signal transducer and activator of transcription 3 activation is associated with bladder cancer cell growth and survival.

Chen CL, Cen L, Kohout J, Hutzen B, Chan C, Hsieh FC, Loy A, Huang V, Cheng G, Lin J - Mol. Cancer (2008)

Bottom Line: Activation of Stat3 is dependent on the phosphorylation at the tyrosine residue 705 by upstream kinases and subsequent nuclear translocation after dimerization.The survival inhibition might be mediated through apoptotic caspase 3, 8 and 9 pathways.Moreover, down-regulation of anti-apoptotic genes (Bcl-2, Bcl-xL and survivin) and a cell cycle regulating gene (cyclin D1) was associated with the cell growth inhibition and apoptosis.

View Article: PubMed Central - HTML - PubMed

Affiliation: Center for Childhood Cancer, The Research Institute at Nationwide Children's Hospital, Columbus, OH 43205, USA. Chun-Liang.Chen@nationwidechildrens.org

ABSTRACT

Background: Constitutive activation of signal transducer and activator of transcription 3 (Stat3) signaling pathway plays an important role in several human cancers. Activation of Stat3 is dependent on the phosphorylation at the tyrosine residue 705 by upstream kinases and subsequent nuclear translocation after dimerization. It remains unclear whether oncogenic Stat3 signaling pathway is involved in the oncogenesis of bladder cancer.

Results: We found that elevated Stat3 phosphorylation in 19 of 100 (19%) bladder cancer tissues as well as bladder cancer cell lines, WH, UMUC-3 and 253J. To explore whether Stat3 activation is associated with cell growth and survival of bladder cancer, we targeted the Stat3 signaling pathway in bladder cancer cells using an adenovirus-mediated dominant-negative Stat3 (Y705F) and a small molecule compound, STA-21. Both prohibited cell growth and induction of apoptosis in these bladder cancer cell lines but not in normal bladder smooth muscle cell (BdSMC). The survival inhibition might be mediated through apoptotic caspase 3, 8 and 9 pathways. Moreover, down-regulation of anti-apoptotic genes (Bcl-2, Bcl-xL and survivin) and a cell cycle regulating gene (cyclin D1) was associated with the cell growth inhibition and apoptosis.

Conclusion: These results indicated that activation of Stat3 is crucial for bladder cancer cell growth and survival. Therefore, interference of Stat3 signaling pathway emerges as a potential therapeutic approach for bladder cancer.

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Related in: MedlinePlus

Inhibition of Stat3 pathway by dnStat3 down-regulates survival genes and cyclin-D1 gene. The protein expression levels are shown in (A) UMUC-3 at 27 hours and (B) WH at 48 hours post-infection with rAd/dnStat3 or the control vector, rAd/eGFP as well as in (C) UMUC-3 and (D) WH that are treated with designated concentrations of STA-21 for 4 days. Protein expressions of survival genes (Bcl-xL, Bcl-2, Mcl-1 and survivin) and cyclin-D1 were subject to densitometric quantification and shown in percents of the untreated controls after being normalized to the GAPDH expression. A representative experiment of triplicates is shown.
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Figure 6: Inhibition of Stat3 pathway by dnStat3 down-regulates survival genes and cyclin-D1 gene. The protein expression levels are shown in (A) UMUC-3 at 27 hours and (B) WH at 48 hours post-infection with rAd/dnStat3 or the control vector, rAd/eGFP as well as in (C) UMUC-3 and (D) WH that are treated with designated concentrations of STA-21 for 4 days. Protein expressions of survival genes (Bcl-xL, Bcl-2, Mcl-1 and survivin) and cyclin-D1 were subject to densitometric quantification and shown in percents of the untreated controls after being normalized to the GAPDH expression. A representative experiment of triplicates is shown.

Mentions: We then would like to explore possible mechanisms for dnStat3-induced cell growth inhibition and activation of apoptotic caspases in bladder cancer cells. It is likely that inhibition of Stat3 pathway by dnStat3 or STA-21 down regulated Bcl-2, Bcl-xL and survivin as well as cell cycle regulating gene, cyclin D1. Reduced expressions of these genes may contribute to bladder cancer cell growth inhibition and apoptotic caspase activation. UMUC-3 and WH cells were transduced with either rAd/eGFP or rAd/dnStat3 (moi = 1000 and 500) for 27 hours and 48 hours, respectively. Expression of survivin, Mcl-1, Bcl-2, Bcl-xL and cyclin D1 proteins in these cells were evaluated using western blot analysis and densitometric quantification. In UMUC-3 cells, Bcl-2 (47% untreated control), Bcl-xL (55.4%) and survivin (9.7%) were down regulated by the transduction of dnStat3 as compared to expressions in untransduced cells or cells transduced with rAd/eGFP (Figure 6A), whereas Mcl-1 (100%) remained intact. Expression of the three genes in rAd/eGFP-transduced cells (moi = 1000) was only slightly changed as compared to the untransduced cells. survivin(67.1% untreated control), Bcl-xL (61.1%) and cyclin -D1 (62.7%) expression was detected to be decreased when the same cell line treated with 30 μM STA-21 for 4 days (Figure 6C).


Signal transducer and activator of transcription 3 activation is associated with bladder cancer cell growth and survival.

Chen CL, Cen L, Kohout J, Hutzen B, Chan C, Hsieh FC, Loy A, Huang V, Cheng G, Lin J - Mol. Cancer (2008)

Inhibition of Stat3 pathway by dnStat3 down-regulates survival genes and cyclin-D1 gene. The protein expression levels are shown in (A) UMUC-3 at 27 hours and (B) WH at 48 hours post-infection with rAd/dnStat3 or the control vector, rAd/eGFP as well as in (C) UMUC-3 and (D) WH that are treated with designated concentrations of STA-21 for 4 days. Protein expressions of survival genes (Bcl-xL, Bcl-2, Mcl-1 and survivin) and cyclin-D1 were subject to densitometric quantification and shown in percents of the untreated controls after being normalized to the GAPDH expression. A representative experiment of triplicates is shown.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC2577686&req=5

Figure 6: Inhibition of Stat3 pathway by dnStat3 down-regulates survival genes and cyclin-D1 gene. The protein expression levels are shown in (A) UMUC-3 at 27 hours and (B) WH at 48 hours post-infection with rAd/dnStat3 or the control vector, rAd/eGFP as well as in (C) UMUC-3 and (D) WH that are treated with designated concentrations of STA-21 for 4 days. Protein expressions of survival genes (Bcl-xL, Bcl-2, Mcl-1 and survivin) and cyclin-D1 were subject to densitometric quantification and shown in percents of the untreated controls after being normalized to the GAPDH expression. A representative experiment of triplicates is shown.
Mentions: We then would like to explore possible mechanisms for dnStat3-induced cell growth inhibition and activation of apoptotic caspases in bladder cancer cells. It is likely that inhibition of Stat3 pathway by dnStat3 or STA-21 down regulated Bcl-2, Bcl-xL and survivin as well as cell cycle regulating gene, cyclin D1. Reduced expressions of these genes may contribute to bladder cancer cell growth inhibition and apoptotic caspase activation. UMUC-3 and WH cells were transduced with either rAd/eGFP or rAd/dnStat3 (moi = 1000 and 500) for 27 hours and 48 hours, respectively. Expression of survivin, Mcl-1, Bcl-2, Bcl-xL and cyclin D1 proteins in these cells were evaluated using western blot analysis and densitometric quantification. In UMUC-3 cells, Bcl-2 (47% untreated control), Bcl-xL (55.4%) and survivin (9.7%) were down regulated by the transduction of dnStat3 as compared to expressions in untransduced cells or cells transduced with rAd/eGFP (Figure 6A), whereas Mcl-1 (100%) remained intact. Expression of the three genes in rAd/eGFP-transduced cells (moi = 1000) was only slightly changed as compared to the untransduced cells. survivin(67.1% untreated control), Bcl-xL (61.1%) and cyclin -D1 (62.7%) expression was detected to be decreased when the same cell line treated with 30 μM STA-21 for 4 days (Figure 6C).

Bottom Line: Activation of Stat3 is dependent on the phosphorylation at the tyrosine residue 705 by upstream kinases and subsequent nuclear translocation after dimerization.The survival inhibition might be mediated through apoptotic caspase 3, 8 and 9 pathways.Moreover, down-regulation of anti-apoptotic genes (Bcl-2, Bcl-xL and survivin) and a cell cycle regulating gene (cyclin D1) was associated with the cell growth inhibition and apoptosis.

View Article: PubMed Central - HTML - PubMed

Affiliation: Center for Childhood Cancer, The Research Institute at Nationwide Children's Hospital, Columbus, OH 43205, USA. Chun-Liang.Chen@nationwidechildrens.org

ABSTRACT

Background: Constitutive activation of signal transducer and activator of transcription 3 (Stat3) signaling pathway plays an important role in several human cancers. Activation of Stat3 is dependent on the phosphorylation at the tyrosine residue 705 by upstream kinases and subsequent nuclear translocation after dimerization. It remains unclear whether oncogenic Stat3 signaling pathway is involved in the oncogenesis of bladder cancer.

Results: We found that elevated Stat3 phosphorylation in 19 of 100 (19%) bladder cancer tissues as well as bladder cancer cell lines, WH, UMUC-3 and 253J. To explore whether Stat3 activation is associated with cell growth and survival of bladder cancer, we targeted the Stat3 signaling pathway in bladder cancer cells using an adenovirus-mediated dominant-negative Stat3 (Y705F) and a small molecule compound, STA-21. Both prohibited cell growth and induction of apoptosis in these bladder cancer cell lines but not in normal bladder smooth muscle cell (BdSMC). The survival inhibition might be mediated through apoptotic caspase 3, 8 and 9 pathways. Moreover, down-regulation of anti-apoptotic genes (Bcl-2, Bcl-xL and survivin) and a cell cycle regulating gene (cyclin D1) was associated with the cell growth inhibition and apoptosis.

Conclusion: These results indicated that activation of Stat3 is crucial for bladder cancer cell growth and survival. Therefore, interference of Stat3 signaling pathway emerges as a potential therapeutic approach for bladder cancer.

Show MeSH
Related in: MedlinePlus