Estrogen receptor and C19-5-ene-steroid concentrations in the nuclear fraction from human breast carcinoma tissue.

The adrenal-derived estrogen 5-androstene-3 beta,17 beta-diol (ADIOL) is estrogenic at the concentrations found in the blood of Western women. We have now measured the concentrations of both ADIOL and the estrogen receptor (ER) in the nuclear fraction (800 g pellet) of 89 primary human mammary tumors. No difference was found in nuclear ADIOL concentrations in tumors from 45 pre- and 44 postmenopausal women. Significantly higher nuclear ADIOL concentrations were found in 49 ER negative tumors compared to 40 ER positive tumors (P < 0.005). A similar relationship applied in the postmenopausal group (P = 0.01) and the premenopausal group, but in this latter instance failed to reach significance (P = 0.1). In ER positive tumors there was no correlation between ADIOL and ER nuclear levels. ADIOL was present in the total particulate fraction (100,000 g pellet) at twice the concentration found in the nuclear 800 g pellet and again no difference was found in its concentration in tumors from 20 pre- compared to 34 postmenopausal women. Dehydroepiandrosterone was also measured in the 800 g fraction of 45 tumors and its concentration, which was some 10-fold higher than ADIOL and significantly correlated with that steroid, was again independent of menopausal status. The higher concentration of C19-5-ene-steroids in ER negative cellular fractions could be due to differences in their metabolism; ER negative tumors either lack, or possess very low levels of, hydroxysteroid sulfotransferase which catalyzes formation of sulfate esters of C19-5-ene-steroids previously observed to be major metabolites produced by ER positive cells. Higher concentrations of free steroids in ER negative cells would then be available for combination with membranes and non-specific binding sites throughout the cell.

Radioimmunolocalization and selective delivery of radiation in a rat model system: comparison of intact and fragmented antibody.

Monoclonal antibody (MoAb) fragments are known to have advantages over intact immunoglobulins for radioimmunoscintigraphy. It is less clear whether they are as effective in the delivery of radioimmunotherapy. The imaging and dosimetric properties of an intact MoAb, K-1-21, reactive against human kappa light chains (LC) were compared with that of its F(ab')2 and Fab fragments using a normal rat model system. Two days after injection of 131I-K-1-21 into rats bearing antigen-sepharose implants, gamma camera images showed specific localization of the MoAb to the target (kappa LC) but not to the control (lambda LC) implant. Better images were obtained with K-1-21 F(ab')2 than with Fab or intact antibody. Mean kappa implant: blood ratios were 8.6 +/- 3.9 for Fab, 7.9 +/- 1.8 for F(ab')2 and 2.0 +/- 0.3 for intact K-1-21. The improvement associated with the use of 131I-K-1-21 fragments was, however, achieved at the expense of lower absolute values of activity at the target site. Thus the absorbed dose delivered to the implant by the intact K-1-21 was double that delivered with F(ab')2 and six times that delivered with Fab. As intact K-1-21 also delivered a greater radiation dose to normal tissues, F(ab')2 fragments may have the greatest overall advantages for therapy with radionuclide MoAb conjugates.

A rat model system for radioimmunodetection of kappa myeloma antigen on malignant B cells.

A novel experimental model was established in normal rats for studying the localisation and tissue distribution of a murine monoclonal antibody directed against kappa light chain B cell malignancies. The antibody, K-1-21 was raised against human kappa Bence Jones Proteins and reacts with a cell membrane antigen KMA which is restricted to some kappa myeloma and lymphoma cells. In the rat model, kappa or lambda Bence Jones protein-conjugated sepharose was implanted subcutaneously on either flank 24 h before the injection of 131I-labelled K-1-21 or its F(ab')2 fragment. Gamma camera imaging and tissue distribution studies showed specific localisation of the K-1-21 antibody in the kappa sepharose. Injection of F(ab')2 antibody fragments resulted in faster background clearance, earlier delineation of the specific image and significantly higher target to blood ratios than those obtained with the intact antibody. These results suggest that the model may provide an alternative system to tumour xenograft bearing nude mice for studying localisation of antibodies with therapeutic potential.

Dehydroepiandrosterone and androst-5-ene-3 beta,17 beta-diol in human mammary cancer cytosolic and nuclear compartments and their relationship to estrogen receptor.

Dehydroepiandrosterone (DHEA) and 5-androstene-3 beta,17 beta-diol (ADIOL) were determined by radioimmunoassay in human primary mammary cancer cytosol preparations. The range and means +/- S.D. (ng/g, wet weight, of tissue) in individual tumors were: DHE, 12.3 +/- 14.4, n = 34; and ADIOL, 2.7 +/- 2.1, n = 43. In 23 tumors in which both steroids were measured in the same extract, they were significantly correlated, and in these tumors the ratio of ADIOL to DHEA was lower in estrogen receptor (ERC)-negative than in ERC-positive tumors, but this difference was not significant. The ratio of ADIOL to DHEA was 5-fold higher in purified nuclei obtained from pooled primary mammary cancer tissue compared to that in the cytosol. DHEA was present in the cytosol of tumors from premenopausal women in significantly higher concentrations than in cytosols of postmenopausal women [0.73 +/- 0.49 ng/mg cytosol protein (n = 14) versus 0.35 +/- 0.35 (n = 19); p < 0.02], whereas the concentrations of ADIOL were similar [0.12 +/- 0.09 ng/mg cytosol protein (n = 18) and 0.10 +/- 0.11 (n = 25), for pre- and postmenopausal women, respectively]. In ERC-positive tumors, there was a negative correlation between ERC concentration and cytosol ADIOL levels in both premenopausal (r = -0.46, n = 10) and postmenopausal (r = -0.24; n = 20) subjects and also DHEA levels in postmenopausal women only (r = -0.30; n = 12). However, none of these correlations reached statistical significance. In view of the known high affinity of ADIOL for ERC (Kd approximately 6 nM) and its estrogen-like activity in vivo, these data suggest that the concentration of ADIOL in the tumor cytosols is sufficiently high to translocate ERC and provoke an estrogen response.