Proliferative and androgenic effects of indirubin derivatives in LNCaP human prostate cancer cells at sub-apoptotic concentrations.

Abstract

Certain indirubin derivatives are potent cyclin-dependent kinase (CDK) and glycogen synthase kinase (GSK-3β) inhibitors and may be effective against various cancers. We evaluated the effects of aloisine A, alsterpaullone, aminopurvalanol, indirubin-3'-oxime, 6-Br-indirubin-3'-oxime, kenpaullone, olomoucine and roscovitine on cell proliferation, prostate-specific antigen (PSA) expression, androgen receptor (AR) activation, and GSK-3β and β-catenin expression in androgen-dependent LNCaP human prostate cancer cells. Effects were also evaluated in MDA-kb2 human breast cancer cells containing an AR-responsive luciferase construct. Steroid-deprived LNCaP cells were exposed to indirubins±dihydrotestosterone (DHT, 0.1 nM) and cell proliferation was assessed by MTT assay after 120 h. PSA expression was determined by real-time quantitative RT-PCR after 24h. Cytoplasmic and nuclear GSK-3β/β-catenin expression and phosphorylation status was determined by Western blotting. Effects on MDA-kb2 luciferase expression were determined after 24h using Steady-Glo (Promega). Indirubin-3'-oxime, 6-Br-indirubin-3'-oxime, alsterpaullone and kenpaullone increased LNCaP cell proliferation and PSA expression (0.03-1 μM; apoptosis occurred >1 μM), whereas aminopurvalanol significantly (p<0.05) reduced DHT-stimulated PSA expression (31%) at 1 nM. The other indirubin derivatives had no effect. The same was observed for induction of AR-dependent MDA-kb2 luciferase expression. Kenpaullone (1, 3 μM) decreased the active- and increased the inactive form of cytoplasmic GSK-3β, and increased nuclear AR and β-catenin accumulation. Flutamide (10 μM), unexpectedly, also strongly increased nuclear β-catenin accumulation. Indirubin derivatives that were potent GSK-3β inhibitors (relative to CDK1) stimulated LNCaP cell proliferation and other androgenic responses, suggesting (in a cancer treatment context) these compounds may increase AR-dependent prostate cancer growth if not used within an appropriate therapeutic dose-range.

• Authors: Patricia Rivest, Martin Renaud, J Thomas Sanderson
• Journal: Chemico-biological interactions (Chem Biol Interact) Vol. 189 Issue 3 Pg. 177-85 (Feb 01 2011) ISSN: 1872-7786 [Electronic] Ireland
• PMID: 21111724 (Publication Type: Journal Article, Research Support, Non-U.S. Gov't)
• Copyright: Copyright © 2010 Elsevier Ireland Ltd. All rights reserved.

Chemical References

• Androgen Antagonists
• Antibiotics, Antineoplastic
• Indoles
• Receptors, Androgen
• beta Catenin
• Luciferases
• GSK3B protein, human
• Glycogen Synthase Kinase 3 beta
• Glycogen Synthase Kinase 3
• Prostate-Specific Antigen
• indirubin

Topics

• Androgen Antagonists (pharmacology)
• Antibiotics, Antineoplastic (pharmacology)
• Apoptosis (drug effects)
• Breast Neoplasms (metabolism, pathology)
• Dose-Response Relationship, Drug
• Female
• Gene Expression Regulation, Neoplastic (drug effects)
• Glycogen Synthase Kinase 3 (genetics, metabolism)
• Glycogen Synthase Kinase 3 beta
• Humans
• Indoles (pharmacology)
• Luciferases (genetics, metabolism)
• Male
• Prostate-Specific Antigen (genetics, metabolism)
• Prostatic Neoplasms (metabolism, pathology)
• Receptors, Androgen (metabolism)
• Time Factors
• Tumor Cells, Cultured
• beta Catenin (genetics, metabolism)