Proliferative and androgenic effects of indirubin derivatives in LNCaP human prostate cancer cells at sub-apoptotic concentrations.
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.
INRS-Institut Armand-Frappier, Université du Québec, Laval, QC, Canada.
Patricia
P
Rivest
Martin
M
Renaud
J Thomas
JT
Sanderson
D000726:Androgen Antagonists / Q000494:pharmacology*; D000903:Antibiotics, Antineoplastic / Q000494:pharmacology*; D017209:Apoptosis / Q000187:drug effects*; D001943:Breast Neoplasms / Q000378:metabolism / Q000473:pathology; D004305:Dose-Response Relationship, Drug; D005260:Female; D015972:Gene Expression Regulation, Neoplastic / Q000187:drug effects; D038362:Glycogen Synthase Kinase 3 / Q000235:genetics / Q000378:metabolism; D000071679:Glycogen Synthase Kinase 3 beta; D006801:Humans; D007211:Indoles / Q000494:pharmacology; D008156:Luciferases / Q000235:genetics / Q000378:metabolism; D008297:Male; D017430:Prostate-Specific Antigen / Q000235:genetics / Q000378:metabolism; D011471:Prostatic Neoplasms / Q000378:metabolism / Q000473:pathology*; D011944:Receptors, Androgen / Q000378:metabolism; D013997:Time Factors; D014407:Tumor Cells, Cultured; D051176:beta Catenin / Q000235:genetics / Q000378:metabolism
D000726:Androgen Antagonists; D000903:Antibiotics, Antineoplastic; D007211:Indoles; D011944:Receptors, Androgen; D051176:beta Catenin; D008156:Luciferases; C000605506:GSK3B protein, human; D000071679:Glycogen Synthase Kinase 3 beta; D038362:Glycogen Synthase Kinase 3; D017430:Prostate-Specific Antigen; C027185:indirubin