The combined effects of TGF-β, IGF and PDGF on 5α-reductase activity on androgen substrates in human gingival tissue

Effects of cytokines derived from cancer-associated fibroblasts on androgen synthetic enzymes in estrogen receptor-negative breast carcinoma

PURPOSE

The tumor microenvironment plays pivotal roles in promotion of many malignancies. Cancer-associated fibroblasts (CAFs) have been well-known to promote proliferation, angiogenesis, and metastasis but mechanistic understanding of tumor-stroma interactions is not yet complete. Recently, estrogen synthetic enzymes were reported to be upregulated by co-culture with stromal cells in ER positive breast carcinoma (BC) but effects of co-culture on androgen metabolism have not been extensively examined. Therefore, we evaluated roles of CAFs on androgen metabolism in ER-negative AR-positive BC through co-culture with CAFs.

METHODS

Concentrations of steroid hormone in supernatant of co-culture of MDA-MB-453 and primary CAFs were measured using GC-MS. Cytokines derived from CAFs were determined using Cytokine Array. Expressions of androgen synthetic enzymes were confirmed using RT-PCR and Western blotting. Correlations between CAFs and androgen synthetic enzymes were analyzed using triple-negative BC (TNBC) patient tissues by immunohistochemistry.

RESULTS

CAFs were demonstrated to increase expressions and activities of 17βHSD2, 17βHSD5, and 5α-Reductase1. IL-6 and HGF that were selected as potential paracrine mediators using cytokine array induced 17βHSD2, 17βHSD5, and 5α-Reductase1 expression. Underlying mechanisms of IL-6 paracrine regulation of 17βHSD2 and 17βHSD5 could be partially dependent on phosphorylated STAT3, while phosphorylated ERK could be involved in HGF-mediated 5α-Reductase1 induction. α-SMA status was also demonstrated to be significantly correlated with 17βHSD2 and 17βHSD5 status in TNBC tissues, especially AR-positive cases.

CONCLUSIONS

Results of our present study suggest that both IL-6 and HGF derived from CAFs could contribute to the intratumoral androgen metabolism in ER-negative BC patients.

The modulation of androgen metabolism by estradiol, minocycline, and indomethacin in a cell culture model

BACKGROUND

This investigation attempts to clarify the proanabolic effects of minocycline and indomethacin by studying their effects on androgen metabolism and mediation by estradiol. A cell culture model was used with androgen substrates because of the proanabolic effects of androgen metabolites.

METHODS

Monolayer cultures of human gingival fibroblasts (HGF) derived from 6 patients were incubated in duplicate with 14C- testosterone or 14C-4-androstenedione as substrates and optimal concentrations of estradiol (E1,3 microgram/ml) and minocycline (M25 microgram/ml) or indomethacin (I, 1 microgram/ml) alone and in combination (E1,3+11 or E1,3+M25 microgram/ml); similar experiments were carried out with human oral periosteal fibroblasts (HPF), M, I, E, and the combinations. At the end of a 24-hour incubation period in Eagle's MEM, the medium was solvent extracted with ethyl acetate and the metabolites were separated by TLC in a benzene:acetone solvent system (4:1 v/v). The separated metabolites were quantified using a radioisotope scanner.

RESULTS

Both androgens were metabolized to 5alpha-dihydrotestosterone (DHT) and 4-androstenedione (4-A) or testosterone (T) at baseline and in response to the agents tested, by HGF and HPF. With HGF, there were significant increases in the yields of DHT and 4-A or T in response to M, E, and M+E, resulting in 50% to 2.4-fold increases in these metabolites over control incubations (n = 6; P<0.01). The responses to I and combinations of I+E were similar. HPF also demonstrated significant increases of 29% to 4-fold in the yields of androgen metabolites in response to M, E, and M+E (n = 6; P<0.01). I and E similarly increased the yields of androgen metabolites, alone and in combination.

CONCLUSIONS

Adjunctive periodontal treatment with minocycline or indomethacin can contribute to hormone-modulated anabolic responses in males and females in gingival and periosteal fibroblasts derived from a chronically inflamed source.

The effects of human mast-cell products and of phenytoin on androgen 5alpha-reductase expression in human gingival fibroblasts

The aim was to elucidate mechanisms for phenytoin-induced gingival overgrowth, using effects of type 1 human mast cell (HMC-1) supernatant and histamine on the expression of 5alpha-reductase in human gingival fibroblasts (HGF), and the effects of phenytoin on this activity. Duplicate incubations of HGF in Eagle's minimum essential medium (MEM) were performed with [14C] testosterone and serial concentrations of mast-cell histamine (1-100 microgram/ml)/HMC-1 culture supernatant at serial dilutions of 1-100 microl/ml for 24 h. Other experiments employed optimal concentrations of HMC-1 supernatant (10 microl/ml) or histamine (8 microgram/ml) and phenytoin (1 and 5 microgram/ml), alone and in combination, using two androgen substrates, [14C] testosterone and [14C] 4-androstenedione. At the end of a 24-h incubation the medium was solvent-extracted for steroid metabolites, analysed and quantified in a radioisotope scanner. HMC-1, histamine (n=3) and phenytoin (n=6) significantly increased the synthesis of dihydrotestosterone and 4-androstenedione by up to 80% (P<0.01); the combination of HMC-1 and phenytoin caused two-fold increases (n=6; P<0.01). The incubations with histamine alone and in combination with phenytoin showed significant stimulation of dihydroxytestosterone and the diols alone and in combination, which was less pronounced in combination. This investigation demonstrates significant stimulation of 5alpha-reductase activity in human gingival fibroblasts by mast-cell supernatant and a specific product histamine, alone and in combination with phenytoin. Androgen 5alpha-reductase-mediated anabolic actions in connective tissue are well documented. The findings suggest a novel hypothesis that mast-cell mediated androgen action in the gingiva in response to phenytoin could contribute to gingival overgrowth.

Effects of the anti-androgen finasteride on the modulatory actions of oestradiol on androgen metabolism by human gingival fibroblasts

5 alpha-Reduction of androgen substrates results in the formation of the biologically active androgen 5 alpha-dihydrotestosterone (DHT), while 17 beta-hydroxysteroid dehydrogenase metabolises androgen substrates to 4-androstenedione or testosterone. The aim here was to study the effect of the anti-androgen finasteride on 5 alpha-reduction of androgens by human gingival fibroblasts (HGF) and its modulation by oestradiol-17 beta. Duplicate cultures of HGF were incubated with [14C]testosterone/[14C]4-androstenedione in Eagle minimum essential medium (n=6) in the presence or absence of oestradiol-17 beta (O) or finasteride (F; 0.1-3 microg/ml) for 24 h. The steroid metabolites were analysed and quantified using a radioisotope scanner. With [14C]testosterone as substrate, oestradiol stimulated the formation of DHT by 63% (n=6; P<0.01). In contrast, finasteride inhibited this activity by 61% (n=6; P<0.01). The combination of O+F produced 43% less inhibition than finasteride alone (n=6; P<0.01). There were 200-300% increases in the formation of 4-androstenedione in response to O and F, being less pronounced in combination. Oestradiol stimulated the formation of DHT from [14C]4-androstenedione by 300-600% and finasteride reduced the yield of DHT by 40-64%; there was less inhibition in combination with O. There were 300-700% increases in the formation of testosterone in response to F and O alone and in combination (n=6; P<0.01). Oestradiol-induced stimulation of 5 alpha-reductase activity on androgen substrates by HGF is suggestive of hormone modulatory mechanisms in the healing periodontium of both sexes. Its inhibition by finasteride is suggestive of type 2 isoenzyme activity, confirming target-tissue functions in the gingiva.

Implications of minocycline, platelet-derived growth factor, and transforming growth factor-beta on inflammatory repair potential in the periodontium

BACKGROUND

Semisynthetic tetracyclines used in the adjunctive treatment of inflammatory periodontal disease enhance collagen expression in induced periodontal lesions of rats. Polypeptide growth factors regulate key cellular events in tissue repair. The physiologically active androgen 5 alpha-dihydrotestosterone (DHT) stimulates bone and connective tissue turnover. It was relevant to study the effects of transforming growth factor beta (TGF-beta)/platelet-derived growth factor (PDGF) and minocycline alone and in combination on the formation of biologically effective androgens which can influence repair.

METHODS

Confluent monolayer cultures of human gingival fibroblasts of the fifth through the ninth passage were incubated in Eagle's minimum essential medium, with 14C-testosterone/14C-4-androstenedione in the presence or absence of optimal concentrations of TGF-beta/PDGF/minocycline (M), alone and in combination. At the end of a 24-hour incubation period, the medium was analyzed for steroid metabolites and quantified using a radioisotope scanner.

RESULTS

The androgen substrates 14C-testosterone (14C-T) and 14C-4-androstenedione (14C-4-A) were metabolized to DHT and 4-androstenedione/testosterone respectively. There were significant increases in the formation of DHT from 14C-T in response to M, TGF-beta, and PDGF, alone and in combination (13 to 48%), compared with controls (n = 4; P<0.01). The yields of 4-androstenedione were also greater in response to these agents (31%; 3-fold). When 14C-4-A was used as substrate, there were 21 to 80% increases in the formation of DHT in response to these agents alone and in combination (n = 4; P<0.01).

CONCLUSIONS

The biologically effective androgen metabolites formed in response to minocycline, TGF-beta, and PDGF can contribute to reparatory events in the inflamed periodontium. Judicious, adjunctive usage of the chemically-modified tetracyclines in the treatment of periodontal diseases can obviate the risk of microbial resistance, with potential applications of their anti-inflammatory and proanabolic effects in regenerative technology.