Effects of SNP variants in the 17β-HSD2 and 17β-HSD7 genes and 17β-HSD7 copy number on gene transcript and estradiol levels in breast cancer tissue

Transcriptome of 17β-hydroxysteroid dehydrogenase type 2 plays both hormone-dependent and hormone-independent roles in MCF-7 breast cancer cells

Breast cancer is a major cause of cancer-related death for women in western countries. 17β-Hydroxysteroid dehydrogenases (17β-HSDs) play important roles in the last step of sex-hormone activation and the first step of sex-hormone inactivation. 17β-HSD2 is responsible for oxidizing the sex hormones. We used microarray technology to analyze the effect of 17β-HSD2 on the MCF-7 cell transcript profile after knocking down 17β-HSD2. Five hundred forty-two genes were regulated 1.5-fold or higher after treatment with 17β-HSD2 siRNA. Knocking down 17β-HSD2 interrupted nucleosome assembly. Pathway-Act-Network analysis showed that the MAPK and apoptosis signaling pathways were most regulated. In the gene-gene interaction network analysis, UGT2B15, which is involved in hormone metabolism, was the most regulated core gene. FOS, GREB1, and CXCL12 were the most regulated genes, and CXCL12 was related to tumor migration. Following 17β-HSD2 knock-down, the cell viability decreased to 75.9%. The S-phase percentage decreased by 19.4%, the Q2-phase percentage in cell apoptosis testing increased by 1.5 times, and cell migration decreased to 66.0%. These results were consistent with our gene chip analysis and indicated that 17β-HSD2 plays both hormone-dependent and hormone-independent enzymatic roles. In-depth investigations of this enzyme on the genomic level will help clarify its related molecular mechanisms.

The role of 17βHSDs in breast tissue and breast cancers

The family of seventeen beta hydroxysteroid dehydrogenase enzymes has a long and diverse history in breast and breast cancer research. Given the known dependence of the breast on steroid signalling and intracrine steroid metabolism these enzymes are considered to be essential local fine tuners of overall steroid balance in the tissue. This review will cover the current state of knowledge regarding the expression, clinical effect and biological regulation of enzymes in both cancerous and normal states. In addition we will also cover the current state of knowledge regarding 17βHSD actions in the often neglected adipose and stromal components of tumours.

The interplay of endocrine therapy, steroid pathways and therapeutic resistance: Importance of androgen in breast carcinoma

A great majority of breast carcinomas expresses estrogen receptor (ER) and estrogens have crucial roles in the progress of breast carcinomas. Endocrine therapy targeting ER and/or intratumoral estrogen production significantly improved clinical outcomes of the patients with ER-positive breast carcinomas. However, resistance to endocrine therapy is often observed and significant number of patients will recur after the treatment. In addition, treatment for the patients with triple-negative breast carcinomas (negative for all ER, progesterone receptor (PR) and HER2) are limited to cytotoxic chemotherapy and novel therapeutic targets need to be identified. In breast carcinoma tissues, not only ER but androgen receptor (AR) is frequently expressed, suggesting pivotal roles of androgens in the progress of breast carcinomas. Growing interest on androgen action as possible therapeutic target has been taken, but androgen action seems quite complicated in breast carcinomas and inconsistent findings has been also proposed. In this review, we will summarize recent studies regarding intratumoral androgen production and its regulation as well as distinct subset of breast carcinomas characterized by activated AR signaling and recent clinical trial targeting AR in the patients with either ER-positive and ER-negative breast carcinomas.

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.

Functional Effects of SNPs in MYH9 and Risks of Nonsyndromic Orofacial Clefts

Nonsyndromic orofacial clefts (NSOCs) are congenital newborn malformations. Myosin heavy chain 9 ( MYH9) is a candidate gene of NSOCs. To investigate the associations between single-nucleotide polymorphisms (SNPs) of MYH9 and NSOC susceptibility, a 2-stage case-control study was designed and 4 potentially functional SNPs of MYH9 (rs12107, rs2269529, rs9619601, rs5756130) were selected and genotyped by iPLEX Sequenom MassARRAY and TaqMan assay in the first stage (599 NSOC cases and 590 controls). The significant SNPs in the first stage were replicated in the second stage (676 NSOC cases and 705 controls) by TaqMan assay. Reverse transcription polymerase chain reaction, cell transfection, and luciferase assay were performed accordingly to explore their functionality. In stage I, rs12107 was nominally associated with NSOCs, whereas rs2269529 showed a significant association (rs12107: P_het = 0.028; rs2269529: P_het = 0.001). In stage II, rs12107 was nominally associated with NSOCs, and rs2269529 showed a significant association (rs12107: P_hom = 0.014; rs2269529: P_het = 0.006). In combined stages, these 2 SNPs gained significant associations (rs12107: P_dom = 0.004; rs2269529: P_dom = 4.4 × 10^-5). In subphenotype analysis, these 2 SNPs were associated with cleft lip only (CLO) and cleft lip with palate (CLP), and rs2269529 was also associated with cleft palate only (CPO). Haplotype analysis revealed associations between rs12107-G/rs2269529-T and NSOC susceptibility ( P = 0.011). Combined analysis of rs12107 and rs2269529 indicated the risk of NSOCs increased with the number of risk alleles (rs12107-G and rs2269529-T, P for trend = 0.008). MYH9 SNP rs12107 AG + GG and rs2269529 CT + TT were associated with higher MYH9 expression in lip tissues compared with their corresponding wild-type homozygote. For rs12107, higher luciferase activities of G allele than A allele were observed in the luciferase assay. MYH9 was downregulated when transfecting its putative binding target miR-196b-3p into human embryo plate mesenchyme (HEPM) and C2C12 cell lines. For rs2269529, C > T contributed to increased MYH9 messenger RNA. In conclusion, rs12107 and rs2269529 were associated with the expression of MYH9 and contributed to the susceptibility of NSOCs.

Inhibition of 17beta-hydroxysteroid dehydrogenase type 7 modulates breast cancer protein profile and enhances apoptosis by down-regulating GRP78

17beta-hydroxysteroid dehydrogenase type 7 (17β-HSD7) promotes breast cancer cell growth via dual-catalytic activity by modulating estradiol and DHT. Here, we clarified the expression pattern of 17β-HSD7 in postmenopausal luminal A type breast cancer with The Cancer Genome Atlas (TCGA) cohort. The impact of 17β-HSD7 inhibition on the proteome of MCF-7 cells was investigated and on cell apoptosis was revealed. MCF-7 cells were treated with an efficient inhibitor of 17β-HSD7 (INH7) or with vehicle, and a differential proteomics study was performed using two-dimensional (2D) gel electrophoresis followed by mass spectrometry and ingenuity pathway analysis (IPA). Cell apoptosis was analyzed by flow cytometry, followed by reverse transcription quantitative real-time PCR (RT-qPCR) and Western blot to investigate the expression of apoptosis-related genes. Our data showed 17β-HSD7 is amplified in primary and progressive breast cancer, inhibition of 17β-HSD7 in MCF-7 cells modulated 104 proteins primarily involved in cell death/survival, cell growth and DNA processing. The expression of 78kDa glucose-regulated protein (GRP78) and anti-apoptosis factor Bcl-2 were significantly suppressed via 17β-HSD7 inhibition with INH7, consequently induced MCF-7 cell apoptosis. However, INH7 treatment of T47D, another widely used epithelial ER+ breast cancer cell line, led to an up-regulation of GRP78 expression, resulting in a limited increase in apoptosis. These results suggest cell-specific effects of INH7 in the breast cancer, which is interesting for further study. An combinatory effect on apoptosis by INH7 and Letrozole (aromatase inhibitor) was further demonstrated in MCF-7. Down-regulation of GRP78 via 17β-HSD7 inhibition enhances cell apoptosis in response to Letrozole. This study highlights GRP78 as a key regulator related to 17β-HSD7 inhibition and effect. Taken together, results from the present study suggest a hypothesis that inhibition of 17β-HSD7 would be a complementary strategy to Letrozole by suppression of GRP78 in ER+ breast cancer. However, from a research perspective, further studies have to be carried out with more breast cancer cell lines as well as in vivo model to assess the efficacy of inhibitor combination.

Determination of the topology of endoplasmic reticulum membrane proteins using redox-sensitive green-fluorescence protein fusions

Membrane proteins of the endoplasmic reticulum (ER) are involved in a wide array of essential cellular functions. Identification of the topology of membrane proteins can provide significant insight into their mechanisms of action and biological roles. This is particularly important for membrane enzymes, since their topology determines the subcellular site where a biochemical reaction takes place and the dependence on luminal or cytosolic co-factor pools and substrates. The methods currently available for the determination of topology of proteins are rather laborious and require post-lysis or post-fixation manipulation of cells. In this work, we have developed a simple method for defining intracellular localization and topology of ER membrane proteins in living cells, based on the fusion of the respective protein with redox-sensitive green-fluorescent protein (roGFP). We validated the method and demonstrated that roGFP fusion proteins constitute a reliable tool for the study of ER membrane protein topology, using as control microsomal 11β-hydroxysteroid dehydrogenase (11β-HSD) proteins whose topology has been resolved, and comparing with an independent approach. We then implemented this method to determine the membrane topology of six microsomal members of the 17β-hydroxysteroid dehydrogenase (17β-HSD) family. The results revealed a luminal orientation of the catalytic site for three enzymes, i.e. 17β-HSD6, 7 and 12. Knowledge of the intracellular location of the catalytic site of these enzymes will enable future studies on their biological functions and on the role of the luminal co-factor pool.