Activation of lysosomal enzymes and tumour regression caused by irradiation and steroid hormones

Ball, A.; Barratt, G.M.; Wills, E.D.

European Journal of Cancer and Clinical Oncology 18(5): 489-494


ISSN/ISBN: 0277-5379
PMID: 6889526
DOI: 10.1016/0277-5379(82)90118-3
Accession: 004663545

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The lysosomal enzyme activity and membrane permeability of mouse C3H mammary tumors was studied using quantitative cytochemical methods following irradiation of the tumors with doses of 1500, 3500 or 6000 rad .gamma. rays. No change in the lysosomal enzyme activity was observed immediately after irradiation, but increased enzyme activity and increased membrane permeability were observed 24 h after irradiation with doses of 3500 or 6000 rad. At 24 h after injection of prednisolone there was a marked increase of lysosomal membrane permeability and enzyme activity, and injection of prednisolone soon after irradiation enhanced the effect of irradiation. After a dose of 6000 rad and prednisolone, the lysosomal membrane permeability increased to 191% of the control and the enzyme activity to 326% of the value of the control tumors. Measurement of tumor size after irradiation or after a combined treatment with irradiation and prednisolone showed that a close correlation exists between tumor regression and lysosomal enzyme activity. The experiments support the view that lysosomal enzymes play an important role in tumor regression following irradiation.