TY - JOUR
T1 - HSP27 regulates p53 transcriptional activity in doxorubicin-treated fibroblasts and cardiac H9c2 cells
T2 - p21 upregulation and G2/M phase cell cycle arrest
AU - Venkatakrishnan, C. D.
AU - Dunsmore, Kathy
AU - Wong, Hector
AU - Roy, Sashwathi
AU - Sen, Chandan K.
AU - Wani, Altaf
AU - Zweier, Jay L.
AU - Ilangovan, Govindasamy
PY - 2008/4
Y1 - 2008/4
N2 - Treatment of cancer patients with anthracyclin-based chemotherapeutic drugs induces congestive heart failure by a mechanism involving p53. However, it is not known how p53 aggravates doxorubicin (Dox)-induced toxicity in the heart. On the basis of in vitro acute toxicity assay using heat shock factor-1 (HSF-1) wild-type (HSF-1+/+) and HSF-1-knockout (HSF-1-/-) mouse embryonic fibroblasts and neonatal rat cardiomyocyte-derived H9c2 cells, we demonstrate a novel mechanism whereby heat shock protein 27 (HSP27) regulates transcriptional activity of p53 in Dox-treated cells. Inhibition of p53 by pifithrin-α (PFT-α) provided different levels of protection from Dox that correlate with HSP27 levels in these cells. In HSF-1+/+ cells, PFT-α attenuated Dox-induced toxicity. However, in HSF-1-/- cells (which express a very low level of HSP27 compared with HSF-1+/+ cells), there was no such attenuation, indicating an important role of HSP27 in p53-dependent cell death. On the other hand, immunoprecipitation of p53 was found to coimmunoprecipitate HSP27 and vice versa (confirmed by Western blotting and matrix-assisted laser desorption/ionization time of flight), demonstrating HSP27 binding to p53 in Dox-treated cells. Moreover, upregulation of p21 was observed in HSF-1+/+ and H9c2 cells, indicating that HSP27 binding transactivates p53 and enhances transcription of p21 in response to Dox treatment. Further analysis with flow cytometry showed that increased expression of p21 results in G2/M phase cell cycle arrest in Dox-treated cells. Overall, HSP27 binding to p53 attenuated the cellular toxicity by upregulating p21 and prevented cell death.
AB - Treatment of cancer patients with anthracyclin-based chemotherapeutic drugs induces congestive heart failure by a mechanism involving p53. However, it is not known how p53 aggravates doxorubicin (Dox)-induced toxicity in the heart. On the basis of in vitro acute toxicity assay using heat shock factor-1 (HSF-1) wild-type (HSF-1+/+) and HSF-1-knockout (HSF-1-/-) mouse embryonic fibroblasts and neonatal rat cardiomyocyte-derived H9c2 cells, we demonstrate a novel mechanism whereby heat shock protein 27 (HSP27) regulates transcriptional activity of p53 in Dox-treated cells. Inhibition of p53 by pifithrin-α (PFT-α) provided different levels of protection from Dox that correlate with HSP27 levels in these cells. In HSF-1+/+ cells, PFT-α attenuated Dox-induced toxicity. However, in HSF-1-/- cells (which express a very low level of HSP27 compared with HSF-1+/+ cells), there was no such attenuation, indicating an important role of HSP27 in p53-dependent cell death. On the other hand, immunoprecipitation of p53 was found to coimmunoprecipitate HSP27 and vice versa (confirmed by Western blotting and matrix-assisted laser desorption/ionization time of flight), demonstrating HSP27 binding to p53 in Dox-treated cells. Moreover, upregulation of p21 was observed in HSF-1+/+ and H9c2 cells, indicating that HSP27 binding transactivates p53 and enhances transcription of p21 in response to Dox treatment. Further analysis with flow cytometry showed that increased expression of p21 results in G2/M phase cell cycle arrest in Dox-treated cells. Overall, HSP27 binding to p53 attenuated the cellular toxicity by upregulating p21 and prevented cell death.
KW - Cell survival
KW - DNA repair
KW - Oxidative stress
KW - Redox signaling
UR - http://www.scopus.com/inward/record.url?scp=41749103345&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=41749103345&partnerID=8YFLogxK
U2 - 10.1152/ajpheart.91507.2007
DO - 10.1152/ajpheart.91507.2007
M3 - Article
C2 - 18263706
AN - SCOPUS:41749103345
SN - 0363-6135
VL - 294
JO - American Journal of Physiology - Heart and Circulatory Physiology
JF - American Journal of Physiology - Heart and Circulatory Physiology
IS - 4
ER -