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Transcription profiling of human estrogen receptor positive MCF7 cells stably transfected with aromatase gene treated with testosterone, 17 B-estradiol, two aromatase inhibitors (letrozole and anastrozole), and an anti-estrogen (tamoxifen)

ABSTRACT: Anti-estrogens and aromatase inhibitors are important drugs in the treatment of estrogen-dependent breast cancer. In order to investigate the effects of these drugs on gene expression in breast cancer cells, we treated estrogen receptor-positive MCF-7 cells, stably transfected with the aromatase gene (known as MCF-7aro cells), with testosterone, 17β-estradiol, two aromatase inhibitors (letrozole and anastrozole), and an anti-estrogen (tamoxifen). Microarray analyses using Affymetrix Human Genome U133A GeneChips were carried out using total RNA isolated from the control and treated cells. When comparing the effect of each inhibitor on gene expression we observe that letrozole and anastrozole are more similar in terms of the genes they affect, compared to treatment with tamoxifen. The results of this study provide us with a better understanding of the actions of both aromatase inhibitors and anti-estrogens at the molecular level. We believe that the results of this study serve as the first step in identifying unique expression patterns following drug treatment, and that this will ultimately be useful in customizing patient treatment strategies for estrogen-dependent breast cancer. The data presented here have been processed using the R-Project Bioconductor statistical tools package using the affy library. The following were applied: RMA background correction, pmonly probe-level correction, quantile normalization, avgdiff summary method. Raw data is provided in the form of .CEL files.

ORGANISM(S): Homo sapiens

SUBMITTER: Itoh T

PROVIDER: S-ECPF-GEOD-2225 | biostudies-other | 2005 Apr

REPOSITORIES: biostudies-other

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Project description:Response to breast cancer chemoprevention can depend upon host genetic makeup and initiating events leading up to preneoplasia. Increased expression of aromatase and estrogen receptor (ER) is found in conjunction with breast cancer. To investigate response or resistance to endocrine therapy, mice with targeted overexpression of Esr1 or CYP19A1 to mammary epithelial cells were employed, representing two direct pathophysiological interventions in estrogen pathway signaling. Both Esr1 and CYP19A1 overexpressing mice responded to letrozole with reduced hyperplastic alveolar nodule prevalence and decreased mammary epithelial cell proliferation. CYP19A1 overexpressing mice were tamoxifen sensitive but Esr1 overexpressing mice were tamoxifen resistant. Increased ER expression occurred with tamoxifen resistance but no consistent changes in progesterone receptor, pSTAT3, pSTAT5, cyclin D1 or cyclin E levels in association with response or resistance were found. RNA-sequencing (RNA-seq) was employed to seek a transcriptome predictive of tamoxifen resistance using these models and a second tamoxifen-resistant model, BRCA1 deficient/Trp53 haploinsufficient mice. Sixty-eight genes associated with immune system processing were upregulated in tamoxifen-resistant Esr1- and Brca1-deficient mice, whereas genes related to aromatic compound metabolic process were upregulated in tamoxifen-sensitive CYP19A1 mice. Interferon regulatory factor 7 was identified as a key transcription factor regulating these 68 immune processing genes. Two loci encoding novel transcripts with high homology to human immunoglobulin lambda-like polypeptide 1 were uniquely upregulated in the tamoxifen-resistant models. Letrozole proved to be a successful alternative to tamoxifen. Further study of transcriptional changes associated with tamoxifen resistance including immune-related genes could expand our mechanistic understanding and lead to biomarkers predictive of escape or response to endocrine therapies.

Project description:IntroductionTestosterone therapy (TTH) for testosterone deficiency (TD) may lead to elevated estradiol (E2) levels requiring management to avoid unnecessary adverse effects.AimTo examine the impact of aromatase inhibitors, specifically anastrozole (AZ), in men with elevated E2 on TTH.MethodsAll patients on TTH at a high volume sexual medicine practice between 2005 and 2019 were reviewed. Men with E2 levels >60 pg/mL regardless of symptoms or 40-60 pg/mL with subjective symptoms were started on AZ 0.5 mg 3x/week. Routine hormone profile and symptom assessment were completed to ensure symptom resolution, reduction of E2 levels and maintenance of testosterone levels. Multivariable logistic regression was completed to determine predictors of men more likely to respond to therapy.Main outcome measureDemographic and hormonal profiles of men on AZ and predictors of response to therapy.Results1708 men with TD were placed on TTH. Of these, 51 (3%) were treated with AZ (AZ+). After exclusions, 44 (2.6%) had elevated estradiol levels >60 pg/mL or >40 pg/mL with symptoms. Demographics were similar between groups. TTH distribution between groups was different with greater rates of topical TTH in the AZ- groups (AZ+:34.1% vs AZ-:53.5%) and greater rates of intramuscular TTH in the AZ+ group (AZ+:38.6% vs AZ-:18.5%) (P = .017 overall). Of the 44 men treated with AZ, 68.0% had pre-AZ E2 levels ≥60 pg/mL and 32.0% had levels between 40 and 60 pg/mL. Median pre-AZ E2 levels were 65 (interquartile range [IQR], 55-94) pg/mL in comparison to 22 (IQR 15-38) pg/mL post-AZ E2 levels (P < .001). Total testosterone levels were similar before and after AZ use (616 (IQR 548-846) ng/dL and 596 (IQR 419-798) ng/dL, respectively, P = .926). No statistically significant predictive factors of E2 reduction using AZ were found.ConclusionWhile no statistically significant predictors for E2 recovery in men on AZ were found, AZ remains a reasonable option for E2 reduction in men with elevated levels on TTH. Punjani N, Bernie H, Salter C, et al. The Utilization and Impact of Aromatase Inhibitor Therapy in Men With Elevated Estradiol Levels on Testosterone Therapy. Sex Med 2021;9:100378.

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Transcription profiling of human estrogen receptor positive MCF7 cells stably transfected with aromatase gene treated with testosterone, 17 B-estradiol, two aromatase inhibitors (letrozole and anastrozole), and an anti-estrogen (tamoxifen)

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