Pancreatic tumor suppression by benzyl isothiocyanate is associated with inhibition of PI3K/AKT/FOXO pathway.

Abstract

PURPOSE:

Our previous studies have shown that benzyl isothiocyanate (BITC) suppress pancreatic cancer growth by inducing apoptosis but the molecular mechanism was unclear. In this study we hypothesized the involvement of PI3K/AKT/FOXO pathway in BITC-induced apoptosis.

EXPERIMENTAL DESIGN:

Mice were implanted BxPC-3 tumor xenografts and orally gavaged with 12 μmol BITC. Plasma and tumor BITC concentration was estimated by liquid chromatography/tandem mass spectrometry. BxPC-3 and PanC-1 cells were used to elucidate PI3K/AKT/FOXO pathway. Electrophoretic mobility shift assay (EMSA), DNA binding activity, immunofluorescence, and gene transfection were used to delineate the mechanism.

RESULTS:

BITC-treated mice showed 43% less tumor growth as compared with control mice and correlated well with the therapeutic concentrations of 6.5 μmol/L BITC achieved in plasma and 7.5 μmol/g BITC in tumor tissue. Western blot analyses and immunohistochemistry revealed that tumors from BITC-treated mice showed reduced phosphorylation of PI3K, AKT, PDK1, mTOR, FOXO1, and FOXO3a and increased apoptosis. Complementing our in vivo results, we made similar observations in a dose- and time-dependent manner in BITC-treated BxPC-3 and Panc-1 cells. Binding of FOXO1 with 14-3-3 proteins was also reduced drastically by BITC treatment indicating nuclear retention of FOXO1 and this observation was further confirmed with EMSA, immunofluorescence, DNA binding, and upregulation of FOXO-responsive proteins Bim, p27, and p21 in BxPC-3 cells. Overexpression of AKT by transient transfection significantly blocked the modulation of FOXO proteins and protected the cells from BITC-mediated apoptosis and growth suppression.

CONCLUSIONS:

Our results provide convincing evidence on the involvement of PI3K/AKT/FOXO pathway in BITC-mediated pancreatic tumor growth suppression.

• Authors: Srinivas Reddy Boreddy, Kartick C Pramanik, Sanjay K Srivastava
• Journal: Clinical cancer research : an official journal of the American Association for Cancer Research (Clin Cancer Res) Vol. 17 Issue 7 Pg. 1784-95 (Apr 01 2011) ISSN: 1557-3265 [Electronic] United States
• PMID: 21350002 (Publication Type: Journal Article, Research Support, N.I.H., Extramural)

Chemical References

• Antineoplastic Agents
• Apoptosis Regulatory Proteins
• BCL2L11 protein, human
• Bcl-2-Like Protein 11
• Bcl2l11 protein, mouse
• FOXO1 protein, human
• FOXO3 protein, human
• Forkhead Box Protein O1
• Forkhead Box Protein O3
• Forkhead Transcription Factors
• Isothiocyanates
• Membrane Proteins
• Proto-Oncogene Proteins
• Cyclin-Dependent Kinase Inhibitor p27
• benzyl isothiocyanate
• CREB-Binding Protein
• CREBBP protein, human
• p300-CBP Transcription Factors
• p300-CBP-associated factor
• PARP1 protein, human
• Poly (ADP-Ribose) Polymerase-1
• Poly(ADP-ribose) Polymerases
• MTOR protein, human
• Proto-Oncogene Proteins c-akt
• TOR Serine-Threonine Kinases
• I-kappa B Kinase
• Caspase 3
• Sirtuins

Topics

• Acetylation
• Animals
• Antineoplastic Agents (pharmacology)
• Apoptosis Regulatory Proteins (metabolism)
• Bcl-2-Like Protein 11
• CREB-Binding Protein (metabolism)
• Caspase 3 (metabolism)
• Cell Line, Tumor
• Cell Nucleus (metabolism)
• Cell Proliferation (drug effects)
• Cell Survival (drug effects)
• Cyclin-Dependent Kinase Inhibitor p27 (metabolism)
• Down-Regulation
• Forkhead Box Protein O1
• Forkhead Box Protein O3
• Forkhead Transcription Factors (metabolism)
• Humans
• I-kappa B Kinase (metabolism)
• Isothiocyanates (pharmacology)
• Membrane Proteins (metabolism)
• Mice
• Mice, Nude
• Neoplasm Transplantation
• Pancreatic Neoplasms (drug therapy, pathology)
• Phosphatidylinositol 3-Kinases (genetics, physiology)
• Phosphorylation
• Poly (ADP-Ribose) Polymerase-1
• Poly(ADP-ribose) Polymerases (metabolism)
• Protein Processing, Post-Translational
• Protein Transport (drug effects)
• Proto-Oncogene Proteins (metabolism)
• Proto-Oncogene Proteins c-akt (genetics, physiology)
• Signal Transduction (drug effects)
• Sirtuins (metabolism)
• TOR Serine-Threonine Kinases (metabolism)
• Transplantation, Heterologous
• Tumor Burden (drug effects)
• p300-CBP Transcription Factors (metabolism)