Significance of tenascin-C, fibronectin, laminin, collagen IV, alpha5beta1 and alpha9beta1 integrins and fibrotic capsule formation around liver metastases originating from cancers of the digestive tract

Abstract

The formation of a fibrotic capsule around liver metastases may functionally act as a barrier to local invasion. However, the prognostic significance of exstracellular matrix (ECM) and of some integrins' deposition around liver metastases remains unclear. An immunohistochemical investigation was carried out on 55 patients with synchronous liver metastases from colorectal and gastric cancers. Encapsulated metastases were detected in 60% of the cases. The 'non-capsular' cases showed clear immunostaining for tenascin-C, fibronectin, collagen IV, laminin, alphaSMA and integrins. On opposite, most of the cases with 'capsule' were negative for the studied ECM proteins and the two integrins. The patients with 'capsular' pattern had significantly longer median survival after the surgery compared to those with non-encapsulated metastases. The presence of tenascin, fibronectin, fibronectin receptor and laminin, as well as the strong immune signal for alphaSMA and collagen type IV in the sinusoids attached to the liver metastases was associated with a worse prognosis. The cells, forming ECM in the sinusoids attached to metastases in the 'non-capsular' pattern were alphaSMA-positive myofibroblasts. It was shown ultrastructurally that they were HSCs. The results indicate that fibrotic capsule formation is associated with longer survival after surgery. The appearance of tenascin-C and of its receptor at the periphery of liver metastases could be used as a sign of invasiveness.