Stromal expression of urokinase-type plasminogen activator receptor (uPAR) is associated with invasive growth in primary liver cancer.

AIMS/BACKGROUND: Expression of urokinase-type plasminogen activator receptor (uPAR) was studied in 25 hepatocellular carcinomas (HCCs) and seven cholangiocellular carcinomas (CCCs) by immunohistochemistry.

METHODS AND RESULTS: uPAR was expressed mostly by host cells distributed along the tumour-host interface in all cases of HCC and CCC, and its expression was higher in CCC. These uPAR-positive cells were identified as macrophages by observation of serial sections stained for CD68, a marker for macrophages. Cancer cells were positive for uPAR in only one case of poorly differentiated HCC with sarcomatous changes and in three cases of CCC. Hepatocellular carcinomas were classified into two types: those with a fibrous capsule (expansive type) and those without a fibrous capsule (invasive type). Invasive-type HCCs showed more prominent expression of uPAR by macrophages than expansive HCCs (p<0.001), to approximately the same degree as that of CCC. Extrahepatic metastasis was observed in two of 16 expansive HCCs, five of nine invasive HCCs and six of seven CCCs.

CONCLUSIONS: Our findings suggest that uPAR expression mainly by macrophages is associated with invasive growth of cancer cells into the surrounding tissue in primary carcinoma of the liver.