Increased extracellular matrix remodeling is associated with tumor progression in human hepatocellular carcinomas

Matrix metalloproteinase-2 (MMP2) is a key enzyme in the process of extracellular matrix remodeling involved in tumor invasion and metastasis. The activation of MMP2 involves interplay with the membrane type-matrix metalloproteinase-l (MT1-MMP) and the tissue inhibitor of metalloproteinase-2 (TIMP2). In vitro, activated hepatic stellate cells are a main source of MMP2 and collagen I induces MMP2, activation. The steady-state mRNA levels of MMP2, MT1-MMP, TIMP2, collagen I, collagen IV, and laminin yl were compared with MMP2 activity in 55 hepatocellular carcinomas, 47 matching nontumor biopsies and 19 histologically normal livers. In hepatocellular carcinomas, increased collagen I mRNA levels were strongly associated with those of MMP2 (Spearman R = .74, P < .001), MTI-MMP (R = .65, P < .001) and TIMP2 (R = 0.61, P < .001). MMP2 activity was correlated with the mRNA expression of collagen I (R =.45 P < .01), collagen IV (R = .40, P < .01) and laminin gamma1 (R = .33, P < .05). Unlike collagen IV and laminin gamma1 mRNAs, MMP2, MT1-MMP, TIMP2, collagen I mRNA levels were increased in nonencapsulated compared with encapsulated tumors (P < .05). In addition, MMP2 activity was fourfold higher (P < .01) in tumors arising in cirrhotic livers than in those arising in noncirrhotic livers. Moreover, tumor recurrence was associated with 4.6- and 2.8-fold (P < .05) higher collagen I and MMP2 mRNA levels, respectively, in hepatocellular carcinomas arising in cirrhotic livers. Thus, a high extracellular matrix remodeling favors tumor progression in hepatocellular carcinomas.