Activities and quantities of lysosomal enzymes during mammary tumor regression.

The relation of lysosomal enzymes to mammary tumor regression was studied in the highly hormone-dependent MTW9 rat mammary carcinoma. Quantities of the enzymes were determined with the use of a histochemical modification of the single radial immunodiffusion method. Major findings were as follows, (a) Acid phosphatase, arylsulfatase, ßgalactosidase, and 0-glucuronidase significantly increased in total activities after 48 hr of tumor regression, (b) A marked shift toward free (nonsedimentable) enzyme of each acid hydrolase occurred later in the regression process, (c) Regressing tumors contained larger quantities of j3-galactosidase and 0-glucuronidase, and the increased amounts closely corresponded to the increments in activities, (d) De novo synthesis of 0-galactosidase and ß-glucuronidase probably occurred during hormone-dependent tumor regression.