Prostate cancer cells may lose androgen-sensitivity after androgen ablation
therapy, becoming highly invasive and metastatic. The biological mechanism
s responsible for higher tumurogenicity of androgen-independent prostate ca
rcinomas are not entirely known. We demonstrate that androgen receptor regu
lation of adhesion and invasion of prostate cancer cells through modulation
of alpha 6 beta 4 integrin expression may be one of the molecular mechanis
ms responsible of this phenomenon. We found that protein and gene expressio
ns of alpha 6 and beta 4 subunits were strongly reduced in the androgen-sen
sitive cell line LNCaP respect to the androgen-independent PC3 and that tra
nsfection of PC3 cells with a full-length androgen receptor expression vect
or resulted in a decreased expression of alpha 6 beta 4 integrin, reduced a
dhesion on laminin, and suppressed Matrigel invasion. Growth in soft agar w
as also suppressed in androgen receptor-positive PC3 clones. Treatment of a
ndrogen receptor positive clones with the synthetic androgen R1881 further
reduced alpha 6 and beta 4 messenger RNA expression as well as adhesion on
laminin and Matrigel invasion. Our results indicate that androgens regulate
cell-extracellular matrix adhesion and invasion by modulation of integrin
expression and function, thus keeping a low invasive phenotype of prostate
cancer cells.