Mimicking postmenopausal steroid metabolism in breast cancer cell culture: Differences in response to DHEA or other steroids as hormone sources

Intracrine Formation of Steroid Hormones in Breast Cancer, Epidermal Keratinocyte, Dermal Fibroblast, and Adipocyte Cell Lines Measured by LC-MS/MS

Peripheral tissues such as skin and adipose tissue play a crucial role in the intracrine formation of sex steroid hormones, complementing the endocrine and paracrine systems. These mechanisms involve the conversion of dehydroepiandrosterone (DHEA) and its sulfated form-DHEAS-into potent androgenic and estrogenic hormones. In vitro studies using tissue-specific cell lines are essential for unraveling the complex intracrine synthesis of these hormones. This study examined the formation of DHEA, androstenedione (A4), testosterone (T), dihydrotestosterone (DHT), and estradiol (E2) from DHEAS in four cell lines: MCF-7 breast cancer cells, HaCaT keratinocytes, human dermal fibroblasts (HDF), and 3T3-L1 preadipocytes and mature adipocytes, using liquid chromatography-mass spectrometry (LC-MS/MS). MCF-7 cells converted DHEAS to DHEA, A4, T, E2, and DHT, while HaCaT cells produced all these steroids except DHT. Mature 3T3-L1 adipocytes produced DHEA, A4, T, and DHT. By contrast, HDF and 3T3-L1 preadipocytes converted DHEAS only to DHEA and A4. This study highlights the vital role of peripheral tissues, such as skin and adipose tissue, for the intracrine formation of sex hormones and underlines the crucial role of in vitro cell culture models to analyze such effects. The data shed light on the significant impact of androgen metabolism in skin and adipose tissue, which is of great relevance for aging, wound healing, obesity, and lipid metabolism.

Role of hydroxysteroid (17beta) dehydrogenase type 1 in reproductive tissues and hormone-dependent diseases

Abnormal synthesis and metabolism of sex steroids is involved in the pathogenesis of various human diseases, such as endometriosis and cancers arising from the breast and uterus. Steroid biosynthesis is a multistep enzymatic process proceeding from cholesterol to highly active sex steroids via different intermediates. Human Hydroxysteroid (17beta) dehydrogenase 1 (HSD17B1) enzyme shows a high capacity to produce the highly active estrogen, estradiol, from a precursor hormone, estrone. However, the enzyme may also play a role in other steps of the steroid biosynthesis pathway. In this article, we have reviewed the literature on HSD17B1, and summarize the role of the enzyme in hormone-dependent diseases in women as evidenced by preclinical studies.

Estrogen and androgen-converting enzymes 17β-hydroxysteroid dehydrogenase and their involvement in cancer: with a special focus on 17β-hydroxysteroid dehydrogenase type 1, 2, and breast cancer

Sex steroid hormones such as estrogens and androgens are involved in the development and differentiation of the breast tissue. The activity and concentration of sex steroids is determined by the availability from the circulation, and on local conversion. This conversion is primarily mediated by aromatase, steroid sulfatase, and 17β-hydroxysteroid dehydrogenases. In postmenopausal women, this is the primary source of estrogens in the breast. Up to 70-80% of all breast cancers express the estrogen receptor-α, responsible for promoting the growth of the tissue. Further, 60-80% express the androgen receptor, which has been shown to have tissue protective effects in estrogen receptor positive breast cancer, and a more ambiguous response in estrogen receptor negative breast cancers. In this review, we summarize the function and clinical relevance in cancer for 17β-hydroxysteroid dehydrogenases 1, which facilitates the reduction of estrone to estradiol, dehydroepiandrosterone to androstendiol and dihydrotestosterone to 3α- and 3β-diol as well as 17β-hydroxysteroid dehydrogenases 2 which mediates the oxidation of estradiol to estrone, testosterone to androstenedione and androstendiol to dehydroepiandrosterone. The expression of 17β-hydroxysteroid dehydrogenases 1 and 2 alone and in combination has been shown to predict patient outcome, and inhibition of 17β-hydroxysteroid dehydrogenases 1 has been proposed to be a prime candidate for inhibition in patients who develop aromatase inhibitor resistance or in combination with aromatase inhibitors as a first line treatment. Here we review the status of inhibitors against 17β-hydroxysteroid dehydrogenases 1. In addition, we review the involvement of 17β-hydroxysteroid dehydrogenases 4, 5, 7, and 14 in breast cancer.

17beta-hydroxysteroid dehydrogenase type 5 is negatively correlated to apoptosis inhibitor GRP78 and tumor-secreted protein PGK1, and modulates breast cancer cell viability and proliferation

17beta-hydroxysteroid dehydrogenase type 5 (17β-HSD5) is an important enzyme associated with sex steroid metabolism in hormone-dependent cancer. However, reports on its expression and its prognostic value in breast cancer are inconsistent. Here, we demonstrate the impact of 17β-HSD5 expression modulation on the proteome of estrogen receptor-positive (ER+) breast cancer cells. RNA interference technique (siRNA) was used to knock down 17β-HSD5 gene expression in the ER+ breast cancer cell line MCF-7 and the proteome of the 17β-HSD5-knockdown cells was compared to that of MCF-7 cells using two-dimensional (2-D) gel electrophoresis followed by mass spectrometry analysis. Ingenuity pathway analysis (IPA) was additionally used to assess functional enrichment analyses of the proteomic dataset, including protein network and canonical pathways. Our proteomic analysis revealed only four differentially expressed protein spots (fold change > 2, p<0.05) between the two cell lines. The four spots were up-regulated in 17β-HSD5-knockdown MCF-7 cells, and comprised 21 proteins involved in two networks and in functions that include apoptosis inhibition, regulation of cell growth and differentiation, signal transduction and tumor metastasis. Among the proteins are nucleoside diphosphate kinase A (NME1), 78kDa glucose-regulated protein (GRP78) and phosphoglycerate kinase 1 (PGK1). We also showed that expression of 17β-HSD5 and that of the apoptosis inhibitor GRP78 are strongly but negatively correlated. Consistent with their opposite regulation, GRP78 knockdown decreased MCF-7 cell viability whereas 17β-HSD5 knockdown or inhibition increased cell viability and proliferation. Besides, IPA analysis revealed that ubiquitination pathway is significantly affected by 17β-HSD5 knockdown. Furthermore, IPA predicted the proto-oncogene c-Myc as an upstream regulator linked to the tumor-secreted protein PGK1. The latter is over-expressed in invasive ductal breast carcinoma as compared with normal breast tissue and its expression increased following 17β-HSD5 knockdown. Our present results indicate a 17β-HSD5 role in down-regulating breast cancer development. We thus propose that 17β-HSD5 may not be a potent target for breast cancer treatment but its low expression could represent a poor prognosis factor.

Simultaneous quantification of estrogens, their precursors and conjugated metabolites in human breast cancer cells by LC-HRMS without derivatization

Liquid chromatography-mass spectrometry (LC-MS) is the state of the art technique for quantification of steroid hormones. Currently used methods are typically limited by the need of pre-column derivatization to increase ionization efficiency; however, this causes hydrolysis of conjugated metabolites. Our newly established LC-HRMS method is able to simultaneously quantify conjugated and unconjugated steroids without prior derivatization using deuterated internal standards and solid-phase extraction. This assay was validated according to ICH Q2(R1) guidelines for the analysis of the 10 main steroids of the estrogenic pathway, namely 4-androstene-3,17-dione, dehydroepiandrosterone (DHEA), DHEA-3-sulfate, estrone, 17β-estradiol, estriol (16α-OH-17β-estradiol), estrone-3-sulfate, 17β-estradiol-3-(β-d-glucuronide), 17β-estradiol-3-sulfate and testosterone. Assay performance characteristics were excellent with results for accuracy (98.8-101.2%), precision (mean: 2.05%, all ≤2.80%), stability over five freeze-thaw-cycles (95.7-100.4%) and SPE accuracy (96.9-102.0%), as well as suitable lower and upper limits of quantification for cell culture experiments (LLOQ 0.005-2ng/ml, ULOQ 3-2000ng/ml). Furthermore, we demonstrated the functionality of our method for the monitoring of steroid levels in the human breast cancer cell line MCF-7. This sensitive assay allows for the first time detailed investigations on estrogen metabolomics in breast cancer cells and may also apply to other estrogen-dependent tumor entities.