Glucose-6-phosphate dehydrogenase and 6-phosphogluconate dehydrogenase activities in normal canine mammary gland and in mammary tumours and their correlation with oestrogen receptors.

Glucose-6-phosphate dehydrogenase (G-6-PD) and 6-phosphogluconate dehydrogenase (6-PGD) activities were studied in 10 normal canine mammary glands and in 19 canine mammary tumours, which included seven benign and 12 malignant neoplasms. The malignant tumours were also examined for oestradiol receptors. The mean G-6-PD and 6-PGD activities were 5.17 +/- 1.84 and 1.65 +/- 0.64 IU per g protein in normal glands, 8.8 +/- 2.7 and 3.8 +/- 0.99 IU per g protein in benign and 19.6 +/- 5.2 and 8.5 +/- 2.1 IU per g protein in malignant mammary tumours. The enzyme activities were significantly higher in tumour tissue than in normal glands. Malignant tumours had much greater activity than benign. With the increasing anaplasia, there was a corresponding rise in the activity of the two enzymes. There was an inverse correlation between the oestrogen receptor (ER) status and the enzyme activity. The ER-positive tumours had low and ER-negative tumours had high enzyme activities.