Effect of cysteine on the survival of mice with transplanted malignant thymoma

Abstract

TISSUE collagenase has been detected in inflamed human tissues by Fullmer and Gibson¹, and in some malignant neoplasms by Riley and Peacock². The possible role of tissue collagenase in neoplastic spread has been suggested by Birbeck and Wheatley³ from an electron microscopic study of the invasion of ascites tumour cells into the abdominal wall of BALB/c mice. They reported that the tumour cells appeared to be actively destroying adjacent normal tissues, which is suggestive of the activity of tissue-destroying enzymes derived from the neoplastic cells. The finding of collagenase activity in human and animal tumours by Riley and Peacock², Campbell⁴, and Dresden, Heilman and Schmidt⁵, prompted a study into the effect that collagenase inhibitors might have on the spread of neoplastic disease. It has been reported by Brown and Weller³ that corneal ulcerations which inevitably occur following severe alkali burns are due to endogenously produced collagenase and that they can be prevented by topical application of solutions of collagenase inhibitors such as cysteine. The present investigation was designed to test our hypothesis that collagenase produced in malignant neoplasms is a factor in neoplastic invasion and that by inhibiting its activity the arrest of a malignant neoplastic disease could be achieved. The results reported here of initial experiments demonstrate the beneficial effects of cysteine on the survival rates of animals into which malignant thymomas were transplanted.