In vitro Evidence of Neutral Collagenase Activity in an Invasive Mammalian Tumour

Abstract

ENZYME degradation of macromolecules in the connective tissue of the host may facilitate malignant tumour invasion¹. The pH of tumour extracellular fluid is undefined, although Ashby² has reported values of not less than 6.5 for human tumours in vivo. We discuss here the possible participation of proteolytic enzymes in tumour invasion at neutral pH. Support for this idea has been provided recently by Strauch et al.³, in the isolation of a neutral collagenase from culture fluid of human HeLa cells. There is no doubt that collagenous structures of host tissue at the invasion zone undergo degradation, as the electron micrographs of Birbeck and Wheatley⁴ have shown.