Androgen Control of Cell Proliferation and Cytoskeletal Reorganization in Human Fibrosarcoma Cells

• Published in: The Journal of biological chemistry Vol. 279; no. 2; pp. 937 - 944
• Main Authors: Chauhan, Sanjay, Kunz, Susan, Davis, Kelli, Roberts, Jordan, Martin, Greg, Demetriou, Manolis C., Sroka, Thomas C., Cress, Anne E., Miesfeld, Roger L.
• Format: Journal Article
• Language: English
• Published: Elsevier Inc 09.01.2004; American Society for Biochemistry and Molecular Biology
• ISSN: 0021-9258; 1083-351X
• DOI: 10.1074/jbc.M311325200

We recently generated an HT-1080-derived cell line called HT-AR1 that responds to dihydrotestosterone (DHT) treatment by undergoing cell growth arrest in association with cytoskeletal reorganization and induction of neuroendocrine-like cell differentiation. In this report, we show that DHT induces a dose-dependent increase in G0/G1 growth-arrested cells using physiological levels of hormone. The arrested cells increase in cell size and contain a dramatic redistribution of desmoplakin, keratin 5, and chromogranin A proteins. DHT-induced cytoskeletal changes were also apparent from time lapse video microscopy that showed that androgen treatment resulted in the rapid appearance of neuronal-like membrane extensions. Expression profiling analysis using RNA isolated from DHT-treated HT-AR1 cells revealed that androgen receptor activation leads to the coordinate expression of numerous cell signaling genes including RhoB, PTGF-β, caveolin-2, Egr-1, myosin 1B, and EHM2. Because RhoB has been shown to have a role in tumor suppression and neuronal differentiation in other cell types, we investigated RhoB signaling functions in the HT-AR1 steroid response. We found that steroid induction of RhoB was DHT-specific and that newly synthesized RhoB protein was post-translationally modified and localized to endocytic vesicles. Moreover, treatment with a farnesyl transferase inhibitor reduced DHT-dependent growth arrest, suggesting that prenylated RhoB might function to inhibit HT-AR1 cell proliferation. This was directly shown by transfecting HT-AR1 cells with RhoB coding sequences containing activating or dominant negative mutations.