VEGF and VEGFR-1 are coexpressed by epithelial and stromal cells of renal cell carcinoma.
BACKGROUND
Tumor angiogenesis is a dynamic process that plays a major role in cancer progression. Vascular endothelial growth factor (VEGF) and its receptors play a pivotal role in angiogenesis. The expression of VEGF and its receptors VEGFR-1 and VEGFR-2 in renal cell carcinoma (RCC) was investigated in the perspective of anti-VEGF treatments.


METHODS
Total VEGF protein levels were quantified by enzyme-linked immunosorbent assay (ELISA) in tumor tissue samples from surgical specimens of 65 patients with clear cell RCC. At the cellular level the VEGF isoforms VEGFR-1 and VEGFR-2 mRNA were quantified by real-time quantitative reverse-transcriptase polymerase chain reaction (RT-PCR) in laser-microdissected tumoral epithelial as stromal cells and in corresponding normal tissue compartments. Colocalization of VEGF and VEGFR-1 proteins was studied by triple immunofluorescent labeling.


RESULTS
Protein VEGF in cytosolic extracts was significantly higher in tumoral than in nontumoral tissue (P< .0001). Event-free survival was significantly longer for patients with cytosolic VEGF lower than the cutoff (75th percentile of VEGF protein levels, P= .02). In laser-microdissected epithelial cells, VEGF(121) and VEGFR-1 mRNA expressions were higher in RCC than in corresponding nontumoral kidney (P= .007 and P= .002, respectively); they were also higher in stromal cells of RCC compared with nontumoral kidney (P= .02 and P= .003, respectively). There was no differential VEGFR-2 expression in epithelial or in stromal cells of tumoral or nontumoral kidney. By immunofluorescent labeling VEGF and VEGFR-1 colocalized on RCC tumor epithelial and stromal cells.


CONCLUSIONS
Combined laser microdissection and quantitative RT-PCR, as triple immunofluorescent labeling, underlined the preferential expression of the most soluble VEGF isoform, VEGF(121), and its receptor VEGFR-1, but not VEGFR-2, in epithelial and stromal cells of RCC.
Laboratoire de Pathologie and U728, INSERM, Université Paris 7, Hôpital Saint-Louis, AP-HP, and Institut Universitaire d'Hématologie, Paris, France.
Jacqueline
J
Rivet
Samia
S
Mourah
Hideyuki
H
Murata
Nicolas
N
Mounier
Helena
H
Pisonero
Pierre
P
Mongiat-Artus
Pierre
P
Teillac
Fabien
F
Calvo
Anne
A
Janin
Christine
C
Dosquet
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002292:Carcinoma, Renal Cell / Q000737:chemistry* / Q000473:pathology; D004847:Epithelial Cells / Q000737:chemistry; D005260:Female; D005455:Fluorescent Antibody Technique; D006801:Humans; D007633:Keratins / Q000032:analysis / Q000235:genetics; D007680:Kidney Neoplasms / Q000737:chemistry* / Q000473:pathology; D008297:Male; D042282:Microdissection; D008875:Middle Aged; D012333:RNA, Messenger / Q000032:analysis; D020133:Reverse Transcriptase Polymerase Chain Reaction; D017154:Stromal Cells / Q000737:chemistry; D042461:Vascular Endothelial Growth Factor A / Q000032:analysis* / Q000235:genetics; D040281:Vascular Endothelial Growth Factor Receptor-1 / Q000032:analysis* / Q000235:genetics; D040301:Vascular Endothelial Growth Factor Receptor-2 / Q000032:analysis / Q000235:genetics
D012333:RNA, Messenger; D042461:Vascular Endothelial Growth Factor A; D007633:Keratins; D040281:Vascular Endothelial Growth Factor Receptor-1; D040301:Vascular Endothelial Growth Factor Receptor-2