Androgen and estrogen receptors are present in primary cultures of human synovial macrophages

Macrophages, as antigen-processing and -presenting cells to T lymphocytes, play a key role in the immune system and are suspected to be target cells of the sex hormone-related dimorphism in the immune response peculiar to rheumatoid arthritis (RA) pathology. In the present study, the use of specific monoclonal antibodies revealed immunostaining for androgen and estrogen receptors in primary cultures of macrophages obtained from synovial tissues of patients affected by RA and controls without RA disease. Soluble and nuclear type I (high affinity, low capacity) and type II (lower affinity, greater capacity) sites of androgen or estrogen binding were detected in primary cultures of RA macrophages using radioligand binding assay. Higher levels of type I and type II estrogen receptor compared to those of androgen receptor were found, particularly in the soluble fraction; however, contrary to what was observed in whole synovial tissues, higher steroid receptor concentrations were found in the soluble than in the nuclear fraction of RA synovial macrophages. Binding affinities and receptor contents of cultured synovial macrophages were comparable to those previously reported in other well established sex hormone-responsive cells and tissues. Further, specific messenger ribonucleic acids for sex hormone receptors, encoding for a sequence of the DNA-binding domain of the receptor proteins were revealed by RT-PCR.

Steroid-growth factor interaction in human prostate cancer. 2. Effects of transforming growth factors on androgen metabolism of prostate cancer cells

The ability of human prostate cancer cells to metabolize androgens was assessed through administration of physiological concentration (0.5-10 nM) of tritiated testosterone (T) as precursor and one-step analysis of both T degradation and products' formation by reverse-phase HPLC and on-line radioactive detection after either 24 h or 72 h incubation. Overall, different prostate cancer cells degraded T quite differently, favoring alternatively reductive or oxidative metabolic pathways. In particular, both LNCaP and DU145 cells retained high levels of unconverted T, with a limited production of androstenedione and its 17-keto derivatives and relatively high amounts of dihydrotestosterone (DHT) and 3 alpha-androstanediol (3 alpha-diol). In contrast, PC3 cells quickly degraded T and exhibited high formation rates of androstenedione and 17-keto metabolites, while neither dihydrotestosterone nor 3 alpha-diol were detected after short or longer incubation times. The effects of both TGF alpha (50 ng/mL) and TGF beta 1 (5 ng/mL) on rates and direction of T metabolism were also explored. In LNCaP cells TGF alpha induced a significant (P < 0.04) decrease of the reductive metabolism of T with a corresponding enhancement of the oxidative pathway (P < 0.002), while TGF beta 1 did not significantly affect T metabolism. On the other hand, both reductive and oxidative pathways were only partially influenced by either growth factor in DU145 and PC3 cells, although TGF alpha significantly raised 5 alpha-androstanedione formation and reduced androsterone production in DU145 cells. All the above evidence was confirmed at both 24 h and 72 h or using increasing doses of TGF alpha and TGF beta 1, a peak activity of 50 ng/mL and 5 ng/mL, respectively, being generally encountered. Overall, our data suggest that TGFs may have a role in the growth regulation of hormone-responsive prostate tumor cells through changes of the intracellular contents of biologically active androgen metabolites.

Sex steroids up-regulate E-cadherin expression in hormone-responsive LNCaP human prostate cancer cells

There is convincing evidence that a reduced expression of the E-cadherin cell-cell adhesion molecule associates with low tumor grade and poor prognosis in prostate cancer patients. However, little is known on how E-cadherin levels are regulated in human prostate cancer cells. We have inspected the effect of both androgens and estrogen on the expression of E-cadherin in the hormone-responsive LNCaP prostate tumor cell line, which is endowed with both androgen and estrogen receptors. Using both Dot Blot analysis and immunocytochemistry we have observed that either steroid significantly increased E-cadherin levels in these cells; this effect was not reversed by the simultaneous addition of the relevant antagonist, hydroxyflutamide or ICI-182,780.

Oxidative and reductive pathways of estrogens in hormone responsive and non-responsive human breast cancer cells in vitro

In order to measure the formation and degradation rates of estradiol by human breast cancer cells, after assessing the biochemical basis of hormone responsiveness and growth response to estrogens, we considered both responsive, estrogen receptor (ER) positive, and non-responsive, ER-negative, breast cancer cell lines, i.e. MCF7, ZR75-1 and MDA-MB231. To this end, we employed a novel "intact cell" approach which allows us, after 24 h incubation, to analyze several enzyme activities in sequence, concurrently with the monitoring of labeled precursor degradation. Our investigations led to the following evidence: (a) the reductive activity of the 17 beta-hydroxysteroid oxoreductase (17 beta-HSOR) appears to be higher than the oxidative only in responsive, ER-rich MCF7 and ZR75-1 cells, as also previously observed by others; (b) this activity is, on the contrary, much lower in MDA-MB231 cells and other unresponsive, ER-poor breast cancer cell lines; (c) conversely, the oxidative activity shows an opposite pattern, being limited in MCF7 and ZR75-1 cells and much higher in MDA-MB231 cells. Overall, a 17 beta-HSOR reductive pathway prevails in both MCF7 and ZR75-1 cells, whilst the oxidative pathway is prevalent in MDA-MB231 cells, leading to a large formation of estrone that is no further metabolized, at least in the experimental conditions used. Our results may provide a likely explanation of previous data on the different estrogen content of breast tumor tissues.

Growth of LNCaP human prostate cancer cells is stimulated by estradiol via its own receptor

We report that growth of LNCaP human prostate cancer cells is significantly stimulated (up to 120% above control) by physiological estradiol (E2) concentrations. This growth increase appears to be comparable to that induced by either testosterone or dihydrotestosterone, as also reported by others. This paper presents novel illustrative evidence for estrogen-binding proteins and messenger RNA transcripts in LNCaP cells. In fact, 1) the reverse transcriptase-polymerase chain reaction system documented normal messenger RNA for estrogen receptors (ER); 2) the radioligand binding assay allowed the detection of high affinity, reduced capacity binding sites in both soluble and nuclear cell fractions; and 3) the immunocytochemical analysis showed a consistently intensive staining for both ER and progesterone receptors. Compared to other human estrogen-responsive mammary cancer cells, MCF7 and ZR75-1, ER expression in LNCaP cells was not significantly lower, as shown by levels of the ER transcripts, number of sites per cell, or femtomoles per mg DNA as well as the percentage and intensity of immunocytochemical staining. A relative estimate of ER expression obtained by matching LNCaP with another human prostate cancer cell line, PC3, always displayed significantly and consistently higher levels in LNCaP cells. The detection of relatively high type I ER content in either cell compartment of LNCaP cells was paralleled by a highly intensive staining for progesterone receptors. In addition, evidence that the synthetic androgen R1881 did not compete for type I binding of E2 and that any E2-induced growth was completely reversed by the pure antiestrogen ICI-182,780, but unaffected by the antiandrogen Casodex, clearly suggests that the biological response of LNCaP cells to E2 is mediated via its own receptor.