G. Lindmark et al., STROMAL EXPRESSION OF PLATELET-DERIVED GROWTH-FACTOR BETA-RECEPTOR AND PLATELET-DERIVED GROWTH-FACTOR B-CHAIN IN COLORECTAL-CANCER, Laboratory investigation, 69(6), 1993, pp. 682-689
BACKGROUND: The importance of growth factors, such as platelet-derived
growth factor (PDGF), for stromal activation in colorectal cancer is
unclear. EXPERIMENTAL DESIGN: The expression of beta-receptors for PDG
F, and PDGF B-chain (PDGF AB and PDGF BB) was investigated by immunohi
stologic techniques in full-thickness biopsies from 210 colorectal can
cers. These antigens were detected by the monoclonal antibodies PDGFR-
B2 and PDGF 007, respectively. RESULTS: All tumors contained granular
clusters of PDGF beta-receptor expressing stromal cells, whereas tumor
epithelium was invariably negative. The staining was most prominent i
n vascular cells. There were several cells in the tumor stroma that ex
pressed PDGF AB/BB. Double immunofluorescence stainings in specimens f
rom four patients performed in order to characterize PDGF beta-recepto
r- and PDGF AB/BB expressing cells showed that cells expressing PDGF b
eta-receptors did not express PDGF AB/BB. About 20% of cells in the st
roma expressing PDGF AB/BB were macrophages (CD68-positive cells), whe
reas the nature of the remaining stromal cells expressing PDGF AB/BB c
ould not be disclosed. Furthermore, about 30% of CD68-positive macroph
ages expressed PDGF AB/BB, but not PDGF beta-receptors. The extent of
clusters of PDGF beta-receptor expressing cells varied considerably be
tween tumors, and its prognostic value was considered in the entire tu
mor material. The number of clusters did, however, not correlate to tu
mor differentiation, tumor stage according to Dukes', or outcome. CONC
LUSIONS: The presence of cells expressing PDGF beta-receptor and PDGF
AB/BB respectively, i.e., expression of the receptor and its ligand, f
ulfills two of the prerequisites for a role of PDGF in the activation
of stromal cells in colorectal cancers. The data suggest that stromal
activation, characterized by clusters of PDGF B-receptor expressing ce
lls, is of importance for the formation of tumor stroma per se. Howeve
r, the expression of the PDGF beta-receptor has no potential as a prog
nostic marker.