The effects of medroxyprogesterone acetate on enzyme activities in human endometrial carcinoma

Creatine kinase (CK), isocitrate (ICDH) and glucose-6-phosphate dehydrogenase (G-6-PD) activities and cytosol oestrogen (REc) and progestin (RPc) receptors have been measured in twenty post-menopausal subjects with endometrial carcinoma. Diagnostic curettage and hysterectomy specimens were obtained from each patient with intervening medroxyprogesterone acetate therapy (MPA). In RPc rich tumours the activity of creatine kinase was significantly increased following MPA and was attributed to an increase in the BB-isoform. There was a similar though less significant increase in ICDH activity. Neither CK nor ICDH were significantly increased following MPA therapy in progesterone receptor poor specimens. There was a small but significant increase in G-6-PD activity following MPA regardless of RPc content. REc was decreased in some but not all RPc rich tumours following MPA and the trend was significant. The highly significant increase in CK activity confirms the apparent response of this enzyme to progesterone in normal human endometrium during the menstrual cycle.