Multiple forms of 17β-hydroxysteroid oxidoreductase in human breast tissue

ABSTRACT 17β-Hydroxysteroid oxidoreductase, the enzyme that catalyses the interconversion of oestradiol and oestrone, is known to be present in human breast tissue. However, it is not known whether one or more forms of the enzyme is present. Homogenates of breast adipose tissue and breast glandular tissue were fractionated and fractions assayed in the oxidative direction with NAD+ and NADP+ as coenzymes, and in the reductive direction with NADH and NADPH as coenzymes. Ultracentrifugation of homogenates showed that there was membrane-bound activity and soluble activity. The soluble activity was due to a number of forms of the enzyme with different molecular weights, three in breast adipose tissue and two in breast glandular tissue, as shown by fractionation with (NH4)2SO4 followed by chromatography on Sephadex G-200. The forms of the enzyme isolated differed in their affinities for substrates and coenzymes and in the relative rates at which they catalysed the oxidative and reductive reactions. Preliminary experiments with breast tumours showed that they also contained membrane-bound activity and more than one soluble form of the enzyme.

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17β-Hydroxysteroid dehydrogenases in human breast tissues: purification and characterization of soluble enzymes and the distribution of particulate and soluble forms in adipose, non-adipose and tumour tissues

Journal of Molecular Endocrinology ◽

10.1677/jme.0.0070045 ◽

1991 ◽

Vol 7 (1) ◽

pp. 45-55 ◽

Cited By ~ 10

Author(s):

V. Z. Mann ◽

C. J. Newton ◽

G. H. Tait

Keyword(s):

Molecular Weight ◽

Adipose Tissue ◽

Breast Tissue ◽

Normal Breast ◽

Soluble Form ◽

Human Breast ◽

Molecular Weights ◽

Normal Tissues ◽

Breast Adipose ◽

Soluble Fractions

ABSTRACT 17β-Hydroxysteroid dehydrogenase (17β-HSD) is present in multiple forms in human breast tissue. One soluble form, with a molecular weight of approximately 35 kDa, was purified to near homogeneity from whole normal breast tissue. This form catalysed the oxidation of oestradiol and the reduction of oestrone, with NADP+ and NADPH as the preferred coenzymes. Three other soluble forms with higher molecular weights (in the range 50–80 kDa) were isolated. They catalysed the oxidation of oestradiol but not the reduction of oestrone, and all of them had properties very different from those of the low molecular weight enzyme. Activities of 17β-HSD were measured in particulate and soluble fractions from normal breast adipose and non-adipose tissues, and from breast tumours obtained from post-menopausal women, in the oxidative direction with NAD+ and NADP+ as coenzymes and in the reductive direction with NADH and NADPH as coenzymes. Particulate fractions from tumours had much higher oxidative and reductive activities than those from normal tissues. Soluble fractions from tumours had higher oxidative activities than those from the normal tissues but similar reductive activities. The major soluble form of 17β-HSD in adipose tissue was the 35 kDa enzyme which had both oxidative and reductive activities. In contrast, the majority of the soluble activity in non-adipose tissue was due to enzymes, with molecular weights in the range 50–80 kDa, which had oxidative activity only. The soluble fractions of tumours, like those of non-adipose tissue, contained enzymes with molecular weights in the range 50–80 kDa. In addition, they contained a 35 kDa enzyme with properties different from those of the enzyme with the same molecular weight present in adipose tissue.

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RU486 is a potent inhibitor of aromatase induction in human breast adipose tissue stromal cells

The Journal of Steroid Biochemistry and Molecular Biology ◽

10.1016/s0960-0760(96)00178-1 ◽

1997 ◽

Vol 60 (3-4) ◽

pp. 197-204 ◽

Cited By ~ 10

Author(s):

Martin Schmidt ◽

Georg Löffler

Keyword(s):

Adipose Tissue ◽

Stromal Cells ◽

Potent Inhibitor ◽

Human Breast ◽

Breast Adipose Tissue ◽

Breast Adipose ◽

Adipose Tissue Stromal Cells

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SAT-126 Breast Adipose Tissue Extracellular Vesicles from Obese Women Increase Breast Cancer Aggressiveness - a Novel Mechanism for the Obesity-Breast Cancer Link

Journal of the Endocrine Society ◽

10.1210/jendso/bvaa046.1831 ◽

2020 ◽

Vol 4 (Supplement_1) ◽

Cited By ~ 1

Author(s):

Alberto Benito-Martin ◽

Paul Paik ◽

Malik Mushannen ◽

Priya Bhardwaj ◽

Sonya Oshchepkova ◽

...

Keyword(s):

Breast Cancer ◽

Body Mass Index ◽

Adipose Tissue ◽

Body Mass ◽

Extracellular Vesicles ◽

Human Breast ◽

Mouse Xenograft Model ◽

Breast Adipose Tissue ◽

Breast Adipose

Abstract Background and Objectives: Breast cancer is among the most common cancer in women with 2.1 million new cases detected each year. Numerous studies have demonstrated a connection between body mass index (BMI) and cancer incidence, with obesity (BMI ≥ 30) being responsible for the development of at least 13 types of cancer, and 15% to 20% of total cancer-related mortality. The effects of extracellular vesicles (EVs) derived from the obese adipose tissue microenvironment on breast cancer have not yet been clearly elucidated. Methods: EVs were obtained from media conditioned with human breast adipose tissue from reduction mammoplasty (n=31). Women were healthy at the time of surgery and had no history of breast cancer. Patient samples were stratified based on their body mass index (BMI), with a BMI < 25 considered healthy and a BMI ≥ 25 considered overweight/obese. Breast adipose tissue-derived EVs (AT-EVs) were characterized (Quantitative Mass Spectrometry) and used to treat human breast cancer cell lines, including the ER+ MCF7 and triple negative breast cancer (TNBC) MDA-MB-231. Effects on cell proliferation and migration in vitro, and on tumor growth in a mouse xenograft model, were examined after long-term education with EVs. RNA sequencing was performed to investigate potential reprogramming induced by AT-EVs. Results: We found a positive correlation between protein amount per AT-EV and BMI. Quantitative proteomics of AT-EVs revealed 46 proteins that were significantly higher and 54 proteins that were significantly lower in specimens from women with a BMI ≥ 25 compared to women with a BMI < 25. AT-EVs from patients with a BMI ≥ 25 induced proliferation of MCF7 cells compared to AT-EVs from patients with a BMI < 25. Obese EVs induced a more aggressive phenotype in MDA-MB-231 cells, increasing their invasiveness in vitro. Obese EVs also increased the growth of MCF7 and MDA-MB-231 cells in vivo. Ingenuity pathway analysis of RNA-Seq data identified significant differences in mTOR signaling and canonical pathways associated with altered mitochondrial function. Conclusion: Our studies identify a novel mechanism to explain the obesity-breast cancer link in older women. Namely, that in obesity, the breast microenvironment produces EVs capable of reprogramming breast cancer cells to grow faster and be more aggressive. Identifying which cargo in breast AT-EV mediates these effects may provide new targets for intervention.

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