Combination therapy of insulin-like growth factor binding protein-3 and retinoid X receptor ligands synergize on prostate cancer cell apoptosis in vitro and in vivo.

Abstract

We have previously identified the retinoid X receptor-alpha (RXRalpha) as an insulin-like growth factor binding protein-3 (IGFBP-3) nuclear binding partner, which is required for IGFBP-3-induced apoptosis. In the current study, we investigated the biological interactions of the RXR ligand, VTP194204 and rhIGFBP-3, in vitro and in vivo. In vitro, IGFBP-3 and VTP194204 individually induced apoptosis, and suppressed cell growth in prostate cancer cell lines in an additive manner. In vivo, LAPC-4 xenograft-bearing severe combined immunodeficiency mice treated daily with saline, IGFBP-3, and/or VTP194204 for 3 weeks showed no effect of individual treatments with IGFBP-3 or VTP194204 on tumor growth. However, the combination of IGFBP-3 and VTP194204 treatments inhibited tumor growth by 50% and induced a significant reduction in serum prostate-specific antigen levels. In terminal nucleotidyl transferase-mediated nick end labeling immunohistochemistry of LAPC-4 xenografts, there was modest induction of apoptosis with either IGFBP-3 or VTP194204 individual treatment, but combination therapy resulted in massive cell death, indicating that IGFBP-3 and VTP194204 have a synergistic effect in preventing tumor growth by apoptosis induction. In summary, this is an initial description of the successful therapeutic use of IGFBP-3 as a cancer therapy in vivo, and shows that combination treatment of IGFBP-3 and RXR ligand has a synergistic effect on apoptosis induction leading to substantial inhibition of prostate cancer xenograft growth. Taken together, these observations suggest that combination therapy with IGFBP-3 and RXR ligands may have therapeutic potential for prostate cancer treatment.

• Authors: Bingrong Liu, Kuk-Wha Lee, Heju Li, Liqun Ma, George L Lin, Roshantha A S Chandraratna, Pinchas Cohen
• Journal: Clinical cancer research : an official journal of the American Association for Cancer Research (Clin Cancer Res) Vol. 11 Issue 13 Pg. 4851-6 (Jul 01 2005) ISSN: 1078-0432 [Print] United States
• PMID: 16000583 (Publication Type: Journal Article, Research Support, N.I.H., Extramural, Research Support, Non-U.S. Gov't, Research Support, U.S. Gov't, P.H.S.)

Chemical References

• Insulin-Like Growth Factor Binding Protein 3
• Ligands
• Retinoid X Receptors
• Retinoids
• Prostate-Specific Antigen

Topics

• Animals
• Antineoplastic Combined Chemotherapy Protocols (therapeutic use)
• Apoptosis (drug effects)
• Cell Line, Tumor
• Drug Synergism
• Humans
• Insulin-Like Growth Factor Binding Protein 3 (administration & dosage, pharmacology)
• Ligands
• Male
• Mice
• Mice, SCID
• Prostate-Specific Antigen (blood)
• Prostatic Neoplasms (blood, drug therapy, pathology)
• Retinoid X Receptors (metabolism)
• Retinoids (administration & dosage, metabolism, pharmacology)
• Time Factors
• Xenograft Model Antitumor Assays