Glycocalyceal bodies in a human rectal carcinoma cell line and their interstitial collagenolytic activities

In co-cultivation on a membrane of connective tissue matrix (CTM) obtained from human dura mater, human adenocarcinoma cells (RCM-1) degraded CTM. Morphologically, the destruction of CTM was associated with the shedding of membrane vesicles from the cells. Transmission electron microscopy, using ruthenium red (RR), showed that the shed vesicles were composed of various-sized membrane bound vesicles (MV). A large majority were small glycocalyceal bodies (G-bodies) measuring 20-120 nm in diameter, composed of an amorphous matrix of moderate electron-density surrounded by an RR-positive, trilaminar membrane. G-bodies were separated from medium-sized and large MVs by ultracentrifugation. Ultrastructural observation of the isolated collagen fibrils from CTM co-cultured with RCM-1 cells, showed G-bodies attached to degraded collagen fibrils with characteristic transverse notches along their axes. The lesions occurred as microerosions in the apolar region between the e and d bands of collagen fibrils. Collagenolytic activity in serum-free RCM-1 conditioned medium was localized in the G-body and MV fractions (80% and 20% of the total activity, respectively, when tested against 3H-labeled type I collagen). No activity was detected in the supernatant. The activity in G-bodies was also confirmed by ultrastructural analysis using reconstituted native type I collagen fibrils. The results suggest that RCM-1 cells release interstitial collagenase as a component of G-bodies which facilitates local breakdown of connective tissue during the process of invasion.