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.
Chauhan
Sanjay
S
Department of Biochemistry and Molecular Biophysics, The Arizona Cancer Center, The University of Arizona, Tucson, Arizona 85721, USA.
Kunz
Susan
S
Davis
Kelli
K
Roberts
Jordan
J
Martin
Greg
G
Demetriou
Manolis C
MC
Sroka
Thomas C
TC
Cress
Anne E
AE
Miesfeld
Roger L
RL
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