Androgen control of cell proliferation and cytoskeletal reorganization in human fibrosarcoma cells: role of RhoB signaling.
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-beta, 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.
Department of Biochemistry and Molecular Biophysics, The Arizona Cancer Center, The University of Arizona, Tucson, Arizona 85721, USA.
Sanjay
S
Chauhan
Susan
S
Kunz
Kelli
K
Davis
Jordan
J
Roberts
Greg
G
Martin
Manolis C
MC
Demetriou
Thomas C
TC
Sroka
Anne E
AE
Cress
Roger L
RL
Miesfeld
D000728:Androgens / Q000378:metabolism*; D015152:Blotting, Northern; D015153:Blotting, Western; D002453:Cell Cycle; D002454:Cell Differentiation; D002455:Cell Division; D045744:Cell Line, Tumor; D003599:Cytoskeleton / Q000378:metabolism*; D013196:Dihydrotestosterone / Q000494:pharmacology; D004305:Dose-Response Relationship, Drug; D004705:Endocytosis; D005354:Fibrosarcoma / Q000378:metabolism*; D016193:G1 Phase; D005799:Genes, Dominant; D006801:Humans; D018715:Microscopy, Video; D009154:Mutation; D020411:Oligonucleotide Array Sequence Analysis; D016192:Resting Phase, Cell Cycle; D015398:Signal Transduction; D013997:Time Factors; D014162:Transfection; D020743:rhoB GTP-Binding Protein / Q000378:metabolism*
D000728:Androgens; D013196:Dihydrotestosterone; D020743:rhoB GTP-Binding Protein