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 recepto r (uPAR) was studied in 25 hepatocellular carcinomas (HCCs) and seven chola ngiocellular 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 CC C. 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 we re classified into two types: those with a fibrous capsule (expansive type) and those without a fibrous capsule (invasive type). Invasive-type HCCs sh owed more prominent expression of uPAR by macrophages than expansive HCCs ( p<0.001), to approximately the same degree as that of CCC. Extrahepatic met astasis was observed in two of 16 expansive RCCs, five of nine invasive HCC s and six of seven CCCs. Conclusions: Our findings suggest that uPAR expres sion mainly by macrophages is associated with invasive growth of cancer cel ls into the surrounding tissue in primary carcinoma of the liver.