Small molecule, oligonucleotide-based telomerase template inhibition in combination with cytolytic therapy in an in vitro androgen-independent prostate cancer model

Canales, Benjamin K.; Li, Yingming; Thompson, Melissa G.; Gleason, Joseph M.; Chen, Zhi; Malaeb, Bahaa; Corey, David R.; Herbert, Brittney-Shea; Shay, Jerry W.; Koeneman, Kenneth S.

doi:10.1016/j.urolonc.2005.11.003

« Previous Next »Urologic Oncology: Seminars and Original Investigations
Volume 24, Issue 2 , Pages 141-151, March 2006

Small molecule, oligonucleotide-based telomerase template inhibition in combination with cytolytic therapy in an in vitro androgen-independent prostate cancer model☆

Benjamin K. Canales, M.D., M.P.H.
- Department of Urology, University of Minnesota, Minneapolis, MN 55455, USA
Yingming Li, M.D.
- Department of Urology, University of Minnesota, Minneapolis, MN 55455, USA
Melissa G. Thompson, B.A.
- Department of Cell Biology, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA
Joseph M. Gleason, M.S.
- Department of Urology, University of Minnesota, Minneapolis, MN 55455, USA
Zhi Chen, Ph.D.
- Department of Pharmacology and Biochemistry, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA
Bahaa Malaeb, M.D.
- Department of Urology, University of Minnesota, Minneapolis, MN 55455, USA
David R. Corey, Ph.D.
- Department of Pharmacology and Biochemistry, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA
Brittney-Shea Herbert, Ph.D.
- Department of Cell Biology, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA
- Indiana University Cancer Center and Department of Medical and Molecular Genetics, Indiana University School of Medicine, Indianapolis, IN 46202, USA
Jerry W. Shay, Ph.D.
- Department of Cell Biology, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA
Kenneth S. Koeneman, M.D.
- Department of Urology, University of Minnesota, Minneapolis, MN 55455, USA
- Department of Urology, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA
- Center for Prostate Cancer, University of Minnesota, Minneapolis, MN 55455, USA
- Corresponding author. Tel.: +1-612-626-0964.

Abstract

Purpose

Determine the efficacy and timing of small molecule oligonucleotide-based inhibitors to the enzyme telomerase in an in vitro model of androgen-independent, osseous prostate cancer.

Materials and Methods

Telomerase was inhibited in prostate cancer cell lines C4-2/C4–2B and in controls by using small molecule antisense oligonucleotide-based inhibitors alone or in various combinations of small-dose Taxotere® (sanofi-aventis, Bridgewater, NJ) and/or conditionally replication competent adenovirus (AD-BSP-E1a). After transfection and proliferation, telomerase telomeric repeat amplification protocol and telomere restriction fragment assays were performed, with specific times for evaluating telomere length. Specimens were stained for analysis with hematoxylin and eosin (H&E), terminal deoxynucleotidyl transferase-mediated deoxyuridine triphosphate nick end-labeling (TUNEL), and prostate-specific antigen (PSA).

Results

C4-2/C4–2B cell lines had the shortest initial mean telomere length (approximately 2.5 kilobase [kb]) compared to PC-3 (approximately 5.5 kb). Dose-dependent inhibition of telomerase activity was seen using match oligonucleotide-based inhibitors to telomerase (50% inhibitory concentration 3–5 nm), whereas mismatch compound showed no telomerase inhibition. Significant growth delay and apoptosis in cell lines occurred after >50 days of treatment. Cells treated with combination “triple therapy” (i.e., telomerase inhibitors, adenovirus, and Taxotere®) had the highest amount of apoptosis. Compared to controls, all combination treatment groups had statistically significant reductions in prostate-specific antigen in the conditioned media.

Conclusions

Combining cytotoxic regimens with small molecule inhibitors to telomerase with oligonucleotide-based agents could be beneficial in controlling osseous hormone refractory prostate cancer, as evidenced by these in vitro, preclinical investigations. Telomerase inhibition needs to move into in vivo models and human studies.

Keywords: Telomerase , Telomerase inhibition , Prostate cancer , Oligonucleotide , Docetaxel , Gene therapy

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☆ This work was supported by a New Award Idea, Department of Defense, CDMRP, DAMD 17-01-1-0107 “Targeting Osteoblastic Bone Metastasis with a Novel Site Restricted Gene Therapy” and Department of Defense, CDMRP, DAMD17-02-1-0148 “Targeting Orthotopic and Osseous Prostate Cancer Xenografts with Selective, Systemic Telomerase Inhibition” (K.S.K.), and a subcontract to DOD Consortium Award, DAMD17-03-2-0033 to Emory University (P.I. Jonathan Simmons).

Isis Corporation and Geron Corporation provided small molecule, oligonucleotide-based telomerase template inhibitors used in this study.

PII: S1078-1439(05)00264-4

doi:10.1016/j.urolonc.2005.11.003

« Previous Next »Urologic Oncology: Seminars and Original Investigations
Volume 24, Issue 2 , Pages 141-151, March 2006

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