The in vitro localization of H₃ estradiol in human prostatic carcinoma. An electron microscopic autoradiographic study

The in vitro localization of H₃ estradiol in human prostatic carcinoma was studied in five patients who had not been treated with hormones previously. The isotope was incorporated into the basal and invasive cells but rarely in the differentiated ones of carcinomatous acini. In basal and invasive cells, the grains were localized on the nuclear membranes and associated condensed heterochromatin, and on some mitochondria. The binding of estradiol in prostatic tissues appeared covalent and nonreversible in our preparative techniques for autoradiography. It is tentatively suggested that cytoplasmic binding of estradiol in mitochondria may be associated with the nucleic‐acid‐protein complex found with the organelle membranes. The nuclear binding of the hormone appears associated with the protein portion of the heterochromatin material. Furthermore, the in vitro study has shown that estrogen directly affects some of the prostatic cancer cells within two hours, but the extent of changes in the tumor cells remains undetermined.