Role of fibroblast growth factor receptor signaling in prostate cancer cell survival.
BACKGROUND
Expression of fibroblast growth factors (FGFs) is increased in a substantial fraction of human prostate cancers in vivo and in prostate cancer cell lines. Altered FGF signaling can potentially have a variety of effects, including stimulating cell proliferation and inhibiting cell death. To determine the biologic significance of altered FGF signaling in human prostate cancer, we disrupted signaling by expression of a dominant-negative (DN) FGF receptor in prostate cancer cell lines.


METHODS
PC-3, LNCaP, and DU145 prostate cancer cells were stably transfected with DN FGFR constructs, and LNCaP and DU145 cells were infected with a recombinant adenovirus expressing DN FGFR-1. The effect of DN FGFR-1 expression was assessed by colony-formation assays, cell proliferation assays, flow cytometry, and cytogenetic analysis. Key regulators involved in the G(2)-to-M cell cycle transition were assessed by western blotting to examine cyclin B1 expression and by in vitro kinase assay to assess cdc2 kinase activity.


RESULTS
Stable transfection of the DN FGFR-1 construct inhibited colony formation by more than 99% in all three cell lines. Infection of LNCaP and DU145 prostate cancer cells with adenovirus expressing DN FGFR-1 led to extensive cell death within 48 hours. Flow cytometry and cytogenetic analysis revealed that the DN FGFR-1 receptor led to arrest in the G(2) phase of the cell cycle before cell death. Cyclin B1 accumulated in DN FGFR-1-infected LNCaP cells, but cdc2 kinase activity was decreased.


CONCLUSIONS
These findings reveal an unexpected dependence of prostate cancer cells on FGF receptor signal transduction to traverse the G(2)/M checkpoint. The mechanism for the G(2) arrest is not clear. Our results raise the possibility that FGF-signaling antagonists might enhance the cell death induced by other prostate cancer therapies.
Ozen
M
M
Department of Pathology, Baylor College of Medicine, 2002 Holcombe Blvd., Houston, TX 77030, USA.
Giri
D
D
Ropiquet
F
F
Mansukhani
A
A
Ittmann
M
M
D000256:Adenoviridae / Q000235:genetics; D015153:Blotting, Western; D016203:CDC2 Protein Kinase / Q000378:metabolism; D002453:Cell Cycle; D016923:Cell Death; D002455:Cell Division; D002470:Cell Survival; D002875:Chromosomes; D019926:Cyclin B / Q000096:biosynthesis; D056744:Cyclin B1; D003582:Cytogenetics; D005434:Flow Cytometry; D005799:Genes, Dominant; D006801:Humans; D007763:Lac Operon; D008297:Male; D011233:Precipitin Tests; D011471:Prostatic Neoplasms / Q000378:metabolism*; D017468:Receptors, Fibroblast Growth Factor / Q000378:metabolism* / Q000502:physiology*; D015398:Signal Transduction; D013997:Time Factors; D014162:Transfection; D014407:Tumor Cells, Cultured
C534699:CCNB1 protein, human; D019926:Cyclin B; D056744:Cyclin B1; D017468:Receptors, Fibroblast Growth Factor; D016203:CDC2 Protein Kinase