Peripheral benzodiazepine receptor in human endometrium and endometrial carcinomas

Since elevated concentrations of peripheral benzodiazepine (PBZr) have been reported in some tumors if was of interest to study the distribution PBZr in the endometrium and endometrial carcinoma. A specific ligand or PK 11195 was used to measure PBZr in the mitochondria (m-fraction) and the microsom al fraction (p-fraction). Density of binding sites and binding affinity (K- D) was computed from Scatchard analysis. Binding in both m- and p- fraction s from endometrium and endometrial carcinoma were saturable and of high aff inity. The PBZr density in p-fraction from endometrium was slightly higher than in m-fraction, whereas the binding in m-fraction in endometrial carcin oma was more than 2-fold higher than in p-fraction. The difference between the densities in m-fraction from endometrial cancer and endometrium was hig hly significant (p < 0.005). There was no significant difference in the bin ding affinities (K-D values) for PK 11195 in the various fractions. The sel ective increase in the density of PBZr in mitochondria elf tumors suggests an association with energy demand and utilization and could be of diagnosti c and/or therapeutic value in endometrial cancer. The role of a relatively high density of PBZr in microsomal fractions remains to be elucidated.