On the mechanisms of 12-O-tetradecanoylphorbol-13-acetate-induced growth arrest in pancreatic cancer cells.

Abstract

OBJECTIVES:

Protein kinase C (PKC) is involved in cell growth, differentiation, and apoptosis. We investigated the effects of the PKC activator, the tetradecanylphorbol acetate (TPA), in human pancreatic cancer cells.

METHODS:

Cell proliferation was measured by thymidine incorporation. Expression of cell cycle proteins was investigated by Western blot. Real-time reverse transcriptase-polymerase chain reaction was used to measure p21 messenger RNA expression, whereas knockdown of its expression was accomplished with a specific small interferring RNA. Cell cycle phases were determined by flow cytometry.

RESULTS:

TPA time and concentration dependently inhibited thymidine incorporation in Panc-1 and CD18 cells and induced G2/M cell cycle arrest. The TPA decreased cyclin A and B expression, increased cyclin E, and markedly increased the expression of p21 at both the messenger RNA and protein levels. TPA-induced p21 expression and growth inhibition were blocked by the PKC inhibitor, bisindoylmaleimide. TPA induced extracellular signal-regulated kinase1/2 phosphorylation, whereas the MEK inhibitor, PD98059, blocked the TPA-induced p21 expression. Small interferring RNA targeted to p21 blocked TPA-induced p21 protein expression but not TPA-induced cell growth arrest.

CONCLUSIONS:

TPA-induced p21 expression is mediated by the MEK/ERK pathway but is not involved in TPA-induced growth inhibition. In contrast, cyclin A and cyclin B are likely involved in TPA-induced G2/M arrest because both proteins are involved in S phase and G2/M transition during cell proliferation.

• Authors: Mohammad R Salabat, Xian Z Ding, Jan B Flesche, Micheal B Ujiki, Tyler P Robin, Mark S Talamonti, Richard H Bell Jr, Thomas E Adrian
• Journal: Pancreas (Pancreas) Vol. 33 Issue 2 Pg. 148-55 (Aug 2006) ISSN: 1536-4828 [Electronic] United States
• PMID: 16868480 (Publication Type: Journal Article)

Chemical References

• CCNB1 protein, human
• CDKN1A protein, human
• Cyclin A
• Cyclin B
• Cyclin B1
• Cyclin E
• Cyclin-Dependent Kinase Inhibitor p21
• Flavonoids
• Indoles
• Maleimides
• Protein Kinase Inhibitors
• RNA, Messenger
• Protein Kinase C
• Mitogen-Activated Protein Kinase 1
• Mitogen-Activated Protein Kinase 3
• MAP Kinase Kinase Kinases
• bisindolylmaleimide I
• Tetradecanoylphorbol Acetate
• 2-(2-amino-3-methoxyphenyl)-4H-1-benzopyran-4-one

Topics

• Cell Division
• Cell Line, Tumor
• Cell Proliferation (drug effects)
• Cyclin A (metabolism)
• Cyclin B (metabolism)
• Cyclin B1
• Cyclin E (metabolism)
• Cyclin-Dependent Kinase Inhibitor p21 (genetics, metabolism)
• Flavonoids (pharmacology)
• G2 Phase
• Gene Expression Regulation, Neoplastic (drug effects)
• Humans
• Indoles (pharmacology)
• MAP Kinase Kinase Kinases (antagonists & inhibitors, metabolism)
• Maleimides (pharmacology)
• Mitogen-Activated Protein Kinase 1 (metabolism)
• Mitogen-Activated Protein Kinase 3 (metabolism)
• Pancreatic Neoplasms (genetics, metabolism, pathology)
• Phosphorylation
• Protein Kinase C (antagonists & inhibitors, metabolism)
• Protein Kinase Inhibitors (pharmacology)
• RNA, Messenger (metabolism)
• Tetradecanoylphorbol Acetate (pharmacology)