Correlation between collagenolytic activity and grade of histological differentiation in colorectal tumors

Collagenolytic activity, extracted from 55 tumor and healthy corresponding intestinal control samples, was determined by 3 different assays using soluble type I and fibrillar type I and III collagen, respectively, as substrate. The enzyme extracted from tumor-digested collagen type I reconstituted fibrils and yielded the three-quarter segments characteristic for the action of one of the matrix metalloproteinases: MMP-I or mammalian collagenase. Metal-chelating agents such as EDTA and O-phenanthrolin indeed inhibited this activity. Collagenolytic activities were calculated on the basis of wet weight, total DNA and total extracted protein. Correlations were sought between levels of activity and both clinicopathological stage (Dukes' staging) and grade of histological differentiation. In all the assays applied, significant correlations were found between grade of histological differentiation and collagenolytic activity expressed as the tumor/control ratios: poorly differentiated tumors exhibited a higher tumor/control ratio than well-differentiated tumors. Also, tumors penetrating into the serosa showed a higher tumor/control ratio than tumors invading the muscularis propria only. A relation between collagenolytic activity and clinico-pathological stage was observed only if activities were calculated on a DNA basis. These results confirm a relationship between the histological appearance of a tumor and its enzymatic potential to degrade interstitial collagens.