Integrins are transmembrane glycoproteins that mediate cell-cell and c
ell-matrix interactions. Altered integrin expression may contribute to
tumor progression, invasiveness and metastases. The alpha-V/beta-3 (a
lpha(v) beta(5); osteopontin/vitronectin receptor) has recently been i
mplicated in neovascularization and tumor-induced angiogenesis. alpha(
v)-Subunit also associates with beta(5) to form an alpha(v) beta(5)-co
mplex, another vitronectin receptor. We studied tissue distribution of
alpha(v) beta(3)- and alpha(v) beta(5)-integrins, as well as alpha(1)
- and beta(1)-subunits in nephrectomy samples from 7 subjects with loc
alized renal cell carcinoma. Grossly and histologically uninvolved reg
ions ('normal') from the same nephrectomy specimens were used for comp
arison. Integrin expression was studied with specific monoclonal antib
odies and the immunoperoxidase technique. alpha(v) beta(3) was express
ed in the glomerular epithelial cells, Bowman's capsule, vascular endo
thelium, and weakly in tubular epithelial cells. alpha(v) beta(5) had
a similar distribution except for minimal expression on vascular endot
helium, alpha(1)-Expression was observed in mesangium and but weakly i
n Bowman's capsule. beta(1)-Expression was seen in glomerular epitheli
al cells, Bowman's capsule, vascular epithelium and tubular epithelial
cells. Unlike in 'normals', neoplastic expression was more heterogene
ous. alpha(v) beta(3) was expressed in tumor cells in 4/7 cases, vascu
lar endothelium in 6/6, and in stroma in 4/7. alpha(v) beta(5) was wea
kly expressed in tumor cells in 4/5, vascular endothelium in 5/5, and
stroma in 4/5 cases. alpha(1)-Expression was seen in tumor cells in 3/
7, vascular endothelium in 4/7 and in stroma in 7/7 cases. beta(1)-Exp
ression was seen in tumor cells in 7/7 cases, vascular endothelium in
7/7, and in stroma in 4/7 cases. This study delineates the pattern of
expression of the alpha(v) beta(3)- and alpha(v) beta(5)-integrins in
'normal' and neoplastic human kidney. Variations in alpha(v) beta(3)-
and alpha(v) beta(5)-integrin expression may play a role in normal and
neoplastic processes of the kidney.