Atg5 regulates Phenethyl isothiocyanate-lnduced autophagic and apoptotic cell death in human prostate cancer cells

Ajay Bommareddy, Eun Ryeong Hahm, Dong Xiao, Anna A. Powolny, Alfred L. Fisher, Yu Jiang, Shivendra V. Singh

Research output: Contribution to journalArticle

126 Citations (Scopus)

Abstract

Phenethyl isothiocyanate (PEITC) is a promising cancer chemopreventive agent but the mechanism of its anticancer effect is not fully understood. We now show, for the first time, that PEITC treatment triggers Atg5-dependent autophagic and apoptotic cell death in human prostate cancer cells. Exposure of PC-3 (androgen independent, p53 null) and LNCaP (androgen responsive, wild-type p53) human prostate cancer cells to PEITC resulted in several specific features characteristic of autophagy, including appearance of membranous vacuoles, formation of acidic vesicular organelles, and cleavage and recruitment of microtubule-associated protein 1 light chain 3 (EC3) to autophagosomes. A normal human prostate epithelial cell line (PrEC) was markedly more resistant toward PEITC-mediated cleavage and recruitment of LC3 compared with prostate cancer cells. Although PEITC treatment suppressed activating phosphorylations of Akt and mammalian target of rapamycin (mTOR), which are implicated in regulation of autophagy by different stimuli, processing and recruitment of LC3 was only partially/marginally reversed by ectopic expression of constitutively active Akt or overexpression of mTOR-positive regulator Rheb. The PEITC- mediated apoptotic DNA fragmentation was significantly attenuated in the presence of a pharmacologic inhibitor of autophagy (3-methyl adenine). Transient transfection of LNCaP and PC-3 cells with Atg5-specific small interfering RNA conferred significant protection against PEITC-mediated autophagy as well as apoptotic DNA fragmentation. A xenograft model using PC-3 cells and Caenorhabdltls elegans expressing a Igg-1;GFP fusion protein provided evidence for occurrence of PEITC-induced autophagy in vivo. In conclusion, the present study indicates that Atg5 plays an important role in regulation of PEITC-induced autophagic and apoptotic cell death.

Original languageEnglish (US)
Pages (from-to)3704-3712
Number of pages9
JournalCancer Research
Volume69
Issue number8
DOIs
StatePublished - Apr 15 2009

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Autophagy
Prostatic Neoplasms
DNA Fragmentation
Sirolimus
Androgens
phenethyl isothiocyanate
Microtubule-Associated Proteins
Adenine
Vacuoles
Heterografts
Organelles
Small Interfering RNA
Transfection
Prostate
Epithelial Cells
Phosphorylation
Light
Cell Line

ASJC Scopus subject areas

  • Oncology
  • Cancer Research

Cite this

Atg5 regulates Phenethyl isothiocyanate-lnduced autophagic and apoptotic cell death in human prostate cancer cells. / Bommareddy, Ajay; Hahm, Eun Ryeong; Xiao, Dong; Powolny, Anna A.; Fisher, Alfred L.; Jiang, Yu; Singh, Shivendra V.

In: Cancer Research, Vol. 69, No. 8, 15.04.2009, p. 3704-3712.

Research output: Contribution to journalArticle

Bommareddy, Ajay ; Hahm, Eun Ryeong ; Xiao, Dong ; Powolny, Anna A. ; Fisher, Alfred L. ; Jiang, Yu ; Singh, Shivendra V. / Atg5 regulates Phenethyl isothiocyanate-lnduced autophagic and apoptotic cell death in human prostate cancer cells. In: Cancer Research. 2009 ; Vol. 69, No. 8. pp. 3704-3712.
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abstract = "Phenethyl isothiocyanate (PEITC) is a promising cancer chemopreventive agent but the mechanism of its anticancer effect is not fully understood. We now show, for the first time, that PEITC treatment triggers Atg5-dependent autophagic and apoptotic cell death in human prostate cancer cells. Exposure of PC-3 (androgen independent, p53 null) and LNCaP (androgen responsive, wild-type p53) human prostate cancer cells to PEITC resulted in several specific features characteristic of autophagy, including appearance of membranous vacuoles, formation of acidic vesicular organelles, and cleavage and recruitment of microtubule-associated protein 1 light chain 3 (EC3) to autophagosomes. A normal human prostate epithelial cell line (PrEC) was markedly more resistant toward PEITC-mediated cleavage and recruitment of LC3 compared with prostate cancer cells. Although PEITC treatment suppressed activating phosphorylations of Akt and mammalian target of rapamycin (mTOR), which are implicated in regulation of autophagy by different stimuli, processing and recruitment of LC3 was only partially/marginally reversed by ectopic expression of constitutively active Akt or overexpression of mTOR-positive regulator Rheb. The PEITC- mediated apoptotic DNA fragmentation was significantly attenuated in the presence of a pharmacologic inhibitor of autophagy (3-methyl adenine). Transient transfection of LNCaP and PC-3 cells with Atg5-specific small interfering RNA conferred significant protection against PEITC-mediated autophagy as well as apoptotic DNA fragmentation. A xenograft model using PC-3 cells and Caenorhabdltls elegans expressing a Igg-1;GFP fusion protein provided evidence for occurrence of PEITC-induced autophagy in vivo. In conclusion, the present study indicates that Atg5 plays an important role in regulation of PEITC-induced autophagic and apoptotic cell death.",
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AU - Bommareddy, Ajay

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AU - Powolny, Anna A.

AU - Fisher, Alfred L.

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AU - Singh, Shivendra V.

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AB - Phenethyl isothiocyanate (PEITC) is a promising cancer chemopreventive agent but the mechanism of its anticancer effect is not fully understood. We now show, for the first time, that PEITC treatment triggers Atg5-dependent autophagic and apoptotic cell death in human prostate cancer cells. Exposure of PC-3 (androgen independent, p53 null) and LNCaP (androgen responsive, wild-type p53) human prostate cancer cells to PEITC resulted in several specific features characteristic of autophagy, including appearance of membranous vacuoles, formation of acidic vesicular organelles, and cleavage and recruitment of microtubule-associated protein 1 light chain 3 (EC3) to autophagosomes. A normal human prostate epithelial cell line (PrEC) was markedly more resistant toward PEITC-mediated cleavage and recruitment of LC3 compared with prostate cancer cells. Although PEITC treatment suppressed activating phosphorylations of Akt and mammalian target of rapamycin (mTOR), which are implicated in regulation of autophagy by different stimuli, processing and recruitment of LC3 was only partially/marginally reversed by ectopic expression of constitutively active Akt or overexpression of mTOR-positive regulator Rheb. The PEITC- mediated apoptotic DNA fragmentation was significantly attenuated in the presence of a pharmacologic inhibitor of autophagy (3-methyl adenine). Transient transfection of LNCaP and PC-3 cells with Atg5-specific small interfering RNA conferred significant protection against PEITC-mediated autophagy as well as apoptotic DNA fragmentation. A xenograft model using PC-3 cells and Caenorhabdltls elegans expressing a Igg-1;GFP fusion protein provided evidence for occurrence of PEITC-induced autophagy in vivo. In conclusion, the present study indicates that Atg5 plays an important role in regulation of PEITC-induced autophagic and apoptotic cell death.

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