A positive feedback pathway of estrogen biosynthesis in breast cancer cells is contained by resveratrol

The Aryl Hydrocarbon Receptor and Its Crosstalk: A Chemopreventive Target of Naturally Occurring and Modified Phytochemicals

The aryl hydrocarbon receptor (AhR) is an environmentally sensitive transcription factor (TF) historically associated with carcinogenesis initiation via the activation of numerous carcinogens. Nowadays, the AhR has been attributed to multiple endogenous functions to maintain cellular homeostasis. Moreover, crosstalk, often reciprocal, has been found between the AhR and several other TFs, particularly estrogen receptors (ERs) and nuclear factor erythroid 2-related factor-2 (Nrf2). Adequate modulation of these signaling pathways seems to be an attractive strategy for cancer chemoprevention. Several naturally occurring and synthetically modified AhR or ER ligands and Nrf2 modulators have been described. Sulfur-containing derivatives of glucosinolates, such as indole-3-carbinol (I3C), and stilbene derivatives are particularly interesting in this context. I3C and its condensation product, 3,3'-diindolylmethane (DIM), are classic examples of blocking agents that increase drug-metabolizing enzyme activity through activation of the AhR. Still, they also affect multiple essential signaling pathways in preventing hormone-dependent cancer. Resveratrol is a competitive antagonist of several classic AhR ligands. Its analogs, with ortho-methoxy substituents, exert stronger antiproliferative and proapoptotic activity. In addition, they modulate AhR activity and estrogen metabolism. Their activity seems related to a number of methoxy groups introduced into the stilbene structure. This review summarizes the data on the chemopreventive potential of these classes of phytochemicals, in the context of AhR and its crosstalk modulation.

Red Wine as an Aromatase Inhibitor: A Narrative Review

As estrogen-dependent breast cancer is more affected by the local production of estrogen via aromatase than serum estrogen, aromatase inhibitors for treating breast carcinomas in postmenopausal women have been developed. As the aromatase enzyme converts endogenous androgen to estrogenic compounds, its blockade lowers the in situ production of estrogen, demonstrated to encourage tumor proliferation. Red wine, but not white wine, may have aromatase-inhibiting properties that are being elucidated, although the exact mechanisms of action are not known. Polyphenols, tannins, and resveratrol have all been implicated as aromatase blockers, and there may also be synergistic interplay among selected constituents. The role of red wine would be in chemoprevention, the use of natural or synthetic substances to retard, block, or reverse cancer. One gene encodes aromatase, so aromatase inhibition would stop endogenous estrogen production. The role of aromatase inhibition in breast cancer in premenopausal women is not clear. While animal studies have demonstrated that red wine contains constituents that could block aromatase in vivo, the benefits also exist with nonalcoholic grape seed extract. Further investigation is needed but there are challenges in designing appropriate clinical trials for a substance as variable as red wine. While there is insufficient evidence to advocate for red wine as an aromatase inhibitor, there is sufficient evidence to warrant further investigation.

The Role of Aromatase Enzyme in Hormone Related Diseases and Plant-Based Aromatase Inhibitors as Therapeutic Regimens

Medicinal plants have a long history of use as food and remedy in traditional and modern societies, as well as have been used as herbal drugs and sources of novel bioactive compounds. They provide a wide array of chemical compounds, many of which can not be synthesized via current synthesis methods. Natural products may provide aromatase inhibitory activity through various pathways and may act clinically effective for treating pathologies associated with excessive aromatase secretion including breast, ovarian and endometrial cancers, endometriosis, uterine fibroid, benign prostatic hyperplasia (BPH), prostate cancer, infertility, and gynecomastia. Recent studies have shown that natural products with aromatase inhibitory activity, could also be good options against secondary recurrence of breast cancer by exhibiting chemopreventive effects. Therefore, screening for new plant-based aromatase inhibitors may provide novel leads for drug discovery and development, particularly with increased clinical efficacy and decreased side effects.

A jaboticaba extract prevents prostatic damage associated with aging and high-fat diet intake

Jaboticaba extract prevented the prostatic lesion development in aging and/or overweight mice, mainly interfering in cell proliferation, hormonal and angiogenesis pathways.

PCP4/PEP19 upregulates aromatase gene expression via CYP19A1 promoter I.1 in human breast cancer SK-BR-3 cells

The Purkinje cell protein 4/peptide 19 (PCP4/PEP19) is a novel breast cancer cell expressing peptide, originally found in the neural cells as an anti-apoptotic factor, could inhibit cell apoptosis and enhance cell migration and invasion in human breast cancer cell lines. The expression of PCP4/PEP19 is induced by estrogens in estrogen receptor-positive (ER⁺) MCF-7 cells but also highly expressed in ER^- SK-BR-3 cells. In this study, we investigated the effects of PCP4/PEP19 on aromatase gene expression in MCF-7 and SK-BR-3 human breast cancer cells. In SK-BR-3 cells but not in MCF-7 cells, PCP4/PEP19 knockdown by siRNA silencing decreased the aromatase expression in gene transcriptional level. When PCP4/PEP19 was overexpressed by CMV promoter-driven PCP4/PEP19 expressing plasmid transfection, aromatase gene transcription increased in SK-BR-3 cells. This aromatase gene transcription is mainly mediated through promoter region PI.1, which is usually active in the placental tissue but not in the breast cancer tissue. These results indicate a new function of PCP4/PEP19 that would enhance aromatase gene upregulation to supply estrogens in heterogeneous cancer microenvironment.

Effects of Neonicotinoid Pesticides on Promoter-Specific Aromatase (CYP19) Expression in Hs578t Breast Cancer Cells and the Role of the VEGF Pathway

BACKGROUND

Aromatase (CYP19) is a key enzyme in estrogens biosynthesis. In the mammary gland, CYP19 gene is expressed at low levels under the regulation of its I.4 promoter. In hormone-dependent breast cancer, fibroblast cells surrounding the tumor express increased levels of CYP19 mRNA due to a decrease of I.4 promoter activity and an increase of PII, I.3, and I.7 promoter activity. Little is known about the effects of environmental chemicals on the promoter-specific CYP19 expression.

OBJECTIVE

We aimed to determine the effects of two neonicotinoids (thiacloprid and imidacloprid) on promoter-specific CYP19 expression in Hs578t breast cancer cells and understand the signaling pathways involved.

METHODS

Hs578t cells were exposed to various signaling pathway stimulants or neonicotinoids for 24 h. Promoter-specific expression of CYP19 was determined by real-time quantitative polymerase chain reaction and catalytic activity of aromatase by tritiated water release assay.

RESULTS

To our knowledge, we are the first to demonstrate that the normal I.4 promoter and the breast cancer-relevant PII, I.3, and I.7 promoters of CYP19 are active in these cells. We found that the expression of CYP19 via promoters PII, I.3, and I.7 in Hs578t cells was, in part, dependent on the activation of two VEGF signaling pathways: mitogen-activated protein kinase (MAPK) 1/3 and phospholipase C (PLC). Exposure of Hs578t cells to environmental concentrations of imidacloprid and thiacloprid resulted in a switch in CYP19 promoter usage, involving inhibition of I.4 promoter activity and an increase of PII, I.3, and I.7 promoter-mediated CYP19 expression and aromatase catalytic activity. Greater effects were seen at lower concentrations. Our results suggest that thiacloprid and imidacloprid exert their effects at least partially by inducing the MAPK 1/3 and/or PLC pathways.

CONCLUSIONS

We demonstrated in vitro that neonicotinoids may stimulate a change in CYP19 promoter usage similar to that observed in patients with hormone-dependent breast cancer. https://doi.org/10.1289/EHP2698.

The effects of the standardized extracts of Ginkgo biloba on steroidogenesis pathways and aromatase activity in H295R human adrenocortical carcinoma cells

OBJECTIVES

Aromatase inhibitors that block estrogen synthesis are a proven first-line hormonal therapy for postmenopausal breast cancer. Although it is known that standardized extract of Ginkgo biloba (EGb761) induces anti-carcinogenic effects like the aromatase inhibitors, the effects of EGb761 on steroidogenesis have not been studied yet. Therefore, the effects of EGb761 on steroidogenesis and aromatase activity was studied using a H295R cell model, which was a good in vitro model to predict effects on human adrenal steroidogenesis.

METHODS

Cortisol, aldosterone, testosterone, and 17β-estradiol were evaluated in the H295R cells by competitive enzyme-linked immunospecific assay after exposure to EGb761. Real-time polymerase chain reaction were performed to evaluate effects on critical genes in steroid hormone production, specifically cytochrome P450 (CYP11/ 17/19/21) and the hydroxysteroid dehydrogenases (3β-HSD2 and 17β-HSD1/4). Finally, aromatase activities were measured with a tritiated water-release assay and by western blotting analysis.

RESULTS

H295R cells exposed to EGb761 (10 and 100 μg/mL) showed a significant decrease in 17β-estradiol and testosterone, but no change in aldosterone or cortisol. Genes (CYP19 and 17β-HSD1) related to the estrogen steroidogenesis were significantly decreased by EGb761. EGb761 treatment of H295R cells resulted in a significant decrease of aromatase activity as measured by the direct and indirect assays. The coding sequence/ Exon PII of CYP19 gene transcript and protein level of CYP19 were significantly decreased by EGb761.

CONCLUSIONS

These results suggest that EGb761 could regulate steroidogenesis-related genes such as CYP19 and 17β-HSD1, and lead to a decrease in 17β-estradiol and testosterone. The present study provides good information on potential therapeutic effects of EGb761 on estrogen dependent breast cancer.

Anti-aromatase effect of resveratrol and melatonin on hormonal positive breast cancer cells co-cultured with breast adipose fibroblasts

Targeting the estrogen pathway has been proven effective in the treatment for estrogen receptor positive breast cancer. There are currently two common groups of anti-estrogenic compounds used in the clinic; Selective Estrogen Receptor Modulators (SERMs, e.g. tamoxifen) and Selective Estrogen Enzyme Modulators (SEEMs e.g. letrozole). Among various naturally occurring, biologically active compounds, resveratrol and melatonin have been suggested to act as aromatase inhibitors, which make them potential candidates in hormonal treatment of breast cancer. Here we used a co-culture model in which we previously demonstrated that primary human breast adipose fibroblasts (BAFs) can convert testosterone to estradiol, which subsequently results in estrogen receptor-mediated breast cancer T47D cell proliferation. In the presence of testosterone in this model, we examined the effect of letrozole, resveratrol and melatonin on cell proliferation, estradiol (E2) production and gene expression of CYP19A1, pS2 and Ki-67. Both melatonin and resveratrol were found to be aromatase inhibitors in this co-culture system, albeit at different concentrations. Our co-culture model did not provide any indications that melatonin is also a selective estrogen receptor modulator. In the T47D-BAF co-culture, a melatonin concentration of 20 nM and resveratrol concentration of 20 μM have an aromatase inhibitory effect as potent as 20 nM letrozole, which is a clinically used anti-aromatase drug in breast cancer treatment. The SEEM mechanism of action of especially melatonin clearly offers potential advantages for breast cancer treatment.

Fatty acid synthase inhibition by amentoflavone suppresses HER2/neu (erbB2) oncogene in SKBR3 human breast cancer cells

Fatty acid synthase (FASN) is a potential therapeutic target for treatment of cancer and obesity, and is highly elevated in 30% of HER2-overexpressing breast cancers. Considerable interest has developed in searching for novel FASN inhibitors as therapeutic agents in treatment of HER2-overexpressing breast cancers. Amentoflavone was found to be effective in suppressing FASN expression in HER2-positive SKBR3 cells. Pharmacological inhibition of FASN by amentoflavone specifically down-regulated HER2 protein and mRNA, and caused an up-regulation of PEA3, a transcriptional repressor of HER2. In addition, pharmacological blockade of FASN by amentoflavone preferentially decreased cell viability and induced cell death in SKBR3 cells. Palmitate reduced the cytotoxic effect of amentoflavone, as the percentage of viable cells was increased after the addition of exogenous palmitate. Amentoflavone-induced FASN inhibition inhibited the translocation of SREBP-1 in SKBR3 cells. Amentoflavone inhibited phosphorylation of AKT, mTOR, and JNK. The use of pharmacological inhibitors revealed that the modulation of AKT, mTOR, and JNK phosphorylation required synergistic amentoflavone-induced FASN inhibition and HER2 activation in SKBR3 cells. These results suggest that amentoflavone modulated FASN expression by regulation of HER2-pathways, and induced cell death to enhance chemopreventive or chemotherapeutic activity in HER2-positive breast cancers.

Shu-Gan-Liang-Xue Decoction Simultaneously Down-regulates Expressions of Aromatase and Steroid Sulfatase in Estrogen Receptor Positive Breast Cancer Cells

OBJECTIVE

Estradiol (E2) plays an important role in the development of breast cancer. In postmenopausal women, the estrogen can be synthesized via aromatase (CYP19) pathway and steroid-sulfatase (STS) pathway in peripheral tissues, when the production in ovary has ceased. The objective of our study was to explore the effects of Shu-Gan-Liang-Xue Decoction (SGLXD) on the expressions of CYP19 and STS in estrogen receptor positive breast cancer MCF-7 and T47D cells.

METHODS

The effects of SGLXD on the cell viability of MCF-7 and T47D were analyzed by MTT assay. By quantitative real-time RT-PCR and Western blot, we evaluated the mRNA and protein expressions of CYP19 and STS in MCF-7 and T47D cells after SGLXD treatment.

RESULTS

By MTT assay, the cell viability rates of MCF-7 and T47D were significantly inhibited by SGLXD in a dose-dependent manner, the IC50 values were 40.07 mg/ml for MCF-7 cells and 25.62 mg/ml for T47D cells, respectively. As evidenced by real-time PCR and Western blot, the high concentrations of SGLXD significantly down-regulated the expressions of CYP19 and STS both in the transcript level and the protein level.

CONCLUSION

The results suggest that SGLXD is a potential dual aromatase-sulfatase inhibitor by simultaneously down-regulating the expressions of CYP19 and STS in MCF-7 and T47D cells.

Fatty acid synthase inhibition by amentoflavone induces apoptosis and antiproliferation in human breast cancer cells

Fatty acid synthase (FASN) is highly expressed in breast carcinomas to support their continuous growth and proliferation, but has low expression level in normal tissues. Considerable interest has been developed in searching for novel FASN inhibitors as a therapeutic target for breast cancer. In present study, amentoflavone was isolated from Selaginella tamariscina, a traditional oriental medicine that has been used to treat cancer for many years, and was found to significantly inhibit the in vitro enzymatic activity of FASN at concentrations above 50 microM. Amentoflavone was also found to decrease fatty acid synthesis by the reduction of [(3)H]acetyl-CoA incorporation into lipids in FASN-overexpressed SK-BR-3 human breast cancer cells. Furthermore, this study showed that amentoflavone, at a concentration greater than 75 microM, increased the cleavage-activity of caspase-3 and poly (ADP-ribose) polymerase (PARP), and administration of pan-caspase inhibitor Z-VAD-FMK completely rescued the SK-BR-3 cells from PARP cleavages. The sequential internucleosomal DNA fragmentation in SK-BR-3 cells was observed at a concentration of 100 microM. A decrease in breast cancer cell growth was observed in SK-BR-3 cells at 12 and 24 h post treatment with 100 microM of amentoflavone, followed by a dramatic suppression after 48 h. The inhibition of cancer-growth by amentoflavone was dose-dependent, showing a slight reduction at 50 microM and significant reduction at concentrations of 75 and 100 microM. FASN-nonexpressed NIH-3T3 normal cell growth was not decreased by amentoflavone-treatment, both in time- and dose-dependent manners. These data provide evidence that amentoflavone isolated from S. tamariscina induced breast cancer apoptosis through blockade of fatty acid synthesis.

Tumor aromatase expression as a prognostic factor for local control in young breast cancer patients after breast-conserving treatment

Introduction

We sought to determine whether the levels of expression of 17 candidate genes were associated with locoregional control after breast-conserving treatments of early-stage breast cancers in young, premenopausal women.

Methods

Gene expression was measured by using RT-PCR in the breast tumors of a series of 53 young (younger than 40 years), premenopausal patients. All treatments consisted of primary breast-conserving surgery followed by whole-breast radiotherapy (± regional lymph nodes) with or without systemic treatments (chemotherapy ± hormone therapy). The median follow-up was 10 years.

Results

The 10-year locoregional control rate was 70% (95% CI, 57% to 87%). In univariate analysis, no clinical/pathologic prognostic factors were found to be significantly associated with decreased locoregional control. Expression of three genes was found to be significantly associated with an increased locoregional recurrence rate: low estrogen-receptor β, low aromatase, and high GATA3. Two others were associated with only a trend (P < 0.10): low HER1 and SKP2. In multivariate analysis, only the absence of aromatase was significantly associated with an increased locoregional recurrence rate (P = 0.003; relative risk = 0.49; 95% CI 0.29 to 0.82).

Conclusions

Recent data give credit to the fact that breast cancer in young women is a distinct biologic entity driven by special oncogenic pathways. Our results highlight the role of estrogen-signaling pathways (mainly CYP19/aromatase, GATA3, and ER-β) in the risk of locoregional recurrence of breast cancer in young women. Confirmation in larger prospective studies is needed.