Association of reduced cell adhesion regulator messenger RNA expression with tumor progression in human hepatocellular carcinoma

Abstract

The recently identified cell adhesion regulator (CAR) modulates the process of integrin-mediated cell adhesion. The CAR gene is located on 16q, a locus at which high levels of allelic losses have been demonstrated in advanced human hepatocellular carcinoma (HCC). We studied the possible involvement of the CAR gene in the progression of HCC. With this aim, we determined the expression of CAR mRNA in 30 cases of HCC. Matching pair samples of tumor and adjacent nontumoral liver were analyzed by semiquantitative reverse transcriptase-polymerase chain reaction (RT-PCR). The results were compared with the clinicopathological features of the patients. Every nontumoral liver tissue sample analyzed, expressed CAR mRNA. All tumor samples showed amounts of expression that were equal or lower, compared with those found in their matching controls. Thus, in 16 out of 30 cases (53.3%), CAR mRNA expression in tumor was diminished to less than one tenth of that observed in nontumoral tissue. This group of patients exhibited higher amounts of alpha-fetoprotein, and comprised tumors with poor histological differentiation (Edmondson-Steinert's grades III-IV), higher rates of intrahepatic metastasis and recurrence within the first postoperative year (p < 0.05, respectively). Tumors exhibiting low levels of CAR mRNA were also found to be diagnosed at more advanced TNM stages (p < 0.01). We conclude that downregulation of CAR mRNA expression may play an essential role in the progression of HCC.