Research article

Glycogen synthesis correlates with androgen-dependent growth arrest in prostate cancer

Joachim B Schnier¹ , Kayoko Nishi¹ , Paul H Gumerlock² , Frederic A Gorin³ and E Morton Bradbury^1,4

¹Department of Biochemistry and Molecular Medicine, Tupper Hall, University of California, One Shields Avenue, Davis, CA 95616, USA

²Cancer and Molecular Research Laboratory, University of California Davis Cancer Center, 4501 X Street, Sacramento, CA 95817, USA

³Center for Neuroscience, University of California at Davis, Davis, CA, USA

⁴Los Alamos National Laboratories, Biosciences Division, Los Alamos, NM 87545, USA

author email corresponding author email

BMC Urology 2005, 5:6doi:10.1186/1471-2490-5-6

Published:	24 March 2005

Abstract

Background

Androgen withdrawal in normal prostate or androgen-dependent prostate cancer is associated with the downregulation of several glycolytic enzymes and with reduced glucose uptake. Although glycogen metabolism is known to regulate the intracellular glucose level its involvement in androgen response has not been studied.

Methods

We investigated the effects of androgen on glycogen phosphorylase (GP), glycogen synthase (GS) and on glycogen accumulation in the androgen-receptor (AR) reconstituted PC3 cell line containing either an empty vector (PC3-AR-V) or vector with HPV-E7 (PC3-AR-E7) and the LNCaP cell line.

Results

Androgen addition in PC3 cells expressing the AR mimics androgen ablation in androgen-dependent prostate cells. Incubation of PC3-AR-V or PC3-AR-E7 cells with the androgen R1881 induced G1 cell cycle arrest within 24 hours and resulted in a gradual cell number reduction over 5 days thereafter, which was accompanied by a 2 to 5 fold increase in glycogen content. 24 hours after androgen-treatment the level of Glucose-6-P (G-6-P) had increased threefold and after 48 hours the GS and GP activities increased twofold. Under this condition inhibition of glycogenolysis with the selective GP inhibitor CP-91149 enhanced the increase in glycogen content and further reduced the cell number. The androgen-dependent LNCaP cells that endogenously express AR responded to androgen withdrawal with growth arrest and increased glycogen content. CP-91149 further increased glycogen content and caused a reduction of cell number.

Conclusion

Increased glycogenesis is part of the androgen receptor-mediated cellular response and blockage of glycogenolysis by the GP inhibitor CP-91149 further increased glycogenesis. The combined use of a GP inhibitor with hormone therapy may increase the efficacy of hormone treatment by decreasing the survival of prostate cancer cells and thereby reducing the chance of cancer recurrence.