Analysis of 17beta-hydroxysteroid dehydrogenase types 5, 7, and 12 genetic sequence variants in breast cancer cases from French Canadian Families with high risk of breast and ovarian cancer

Association of genetic polymorphisms with local steroid metabolism in human benign breasts

PURPOSE

Although alterations of concentrations in circulating steroids have been linked to single nucleotide polymorphisms (SNPs) of steroidogenic enzymes, we hypothesized that SNPs of such enzymes located within the breast affect local steroid concentrations more than products of such SNPs absorbed from the circulation.

METHODS

Steroids (estradiol, estrone, testosterone, androstenedione, DHEA, DHEA sulfate, progesterone) in nipple aspirate fluid (NAF) were purified by HPLC and they along with serum steroids were quantified by immunoassays. Polymorphisms of the transporter SLCO2B1 and enzymes HSD3B1, CYP19A1, HSD17B12, AKR1C3, CYP1B1, and SRD5A1 were measured in white blood cell DNA.

RESULTS

Steroid concentrations in NAF of subjects with homozygous minor genotypes differed from those with heterozygotes, i.e., SLCO2B1 (rs2851069) decreased DHEAS (p = 0.04), HSD17B12 (rs11555762) increased estradiol (p < 0.004), and CYP1B1 (rs1056836) decreased estradiol (p = 0.017) and increased progesterone (p = 0.05). Also, in serum, CYP19A1 (rs10046 and rs700518) both decreased testosterone (p = 0.02) and SRD5A1 increased androstenedione (p = 0.006). Steroids in subjects with major homozygotes did not differ from those with heterozygotes indicating recessive characteristics.

CONCLUSIONS

In the breast, SNPs were associated with decreased uptake of DHEAS (SLCO2B1), increased estradiol concentrations through increased oxidoreductase activity (HSD17B12), or decreased estradiol concentrations by presumed formation of 4-hydroxyestradiol (CYP1B1). CYP19A1 was associated with decreased testosterone concentrations in serum but had no significant effect on estrogen or androgen concentrations within the breast. The hormone differences observed in NAF were not usually evident in serum, indicating the importance of assessing the effect of these SNPs within the breast.

Functional genetic variant of HSD17B12 in the fatty acid biosynthesis pathway predicts the outcome of colorectal cancer

Fatty acids are involved in the development and progression of colorectal cancer (CRC). However, genetic effects of fatty acid biosynthesis pathway on CRC outcome are unclear. Cox regression model was used to evaluate genetic effects on CRC overall survival (OS) and progression‐free survival (PFS), accompanied by calculating hazard ratios (HRs) and confidence intervals (CIs). Differential expression analysis, expression quantitative trait loci analysis, dual‐luciferase reporter assay and chromatin immunoprecipitation assay were performed to explore the genetically biological mechanism. The rs10838164 C>T in HSD17B12 was significantly associated with an increased risk of death and progression of CRC (OS, HR = 2.12, 95% CI = 1.40‐3.22, P = 4.03 × 10⁻⁴; PFS, HR = 1.64, 95% CI = 1.11‐2.44, P = 1.35 × 10⁻²), of which T allele could increase HSD17B12 expression (P = 1.78 × 10⁻¹¹). Subsequently, the functional experiments indicated that rs10838164 T allele could not only enhance the binding affinity of transcription factor YY1 to HSD17B12 region harbouring rs10838164 but also promote the transcriptional activity of HSD17B12, which was significantly up‐regulated in colorectal tumour tissues. Our findings suggest that genetic variants in fatty acid biosynthesis pathway play an important role in CRC outcome.

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.

MiR-152 Regulates Apoptosis and Triglyceride Production in MECs via Targeting ACAA2 and HSD17B12 Genes

Mammary epithelial cells (MECs) affect milk production capacity during lactation and are critical for the maintenance of tissue homeostasis. Our previous studies have revealed that the expression of miR-152 was increased significantly in MECs of cows with high milk production. In the present study, bioinformatics analysis identified ACAA2 and HSD17B12 as the potential targets of miR-152, which were further validated by dual-luciferase repoter assay. In addition, the expressions of miR-152 was shown to be negatively correlated with levels of mRNA and protein of ACAA2, HSD17B12 genes by qPCR and western bot analysis. Furthermore, transfection with miR-152 significantly up-regulated triglyceride production, promoted proliferation and inhibited apoptosis in MECs. Furthermore, overexpression of ACAA2 and HSD17B12 could inhibit triglyceride production, cells proliferation and induce apoptosis; but sh234-ACAA2-181/sh234-HSD17B12-474 could reverse the trend. These findings suggested that miR-152 could significantly influence triglyceride production and suppress apoptosis, possibly via the expression of target genes ACAA2 and HSD17B12.

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

Breast cancers reveal elevated E2 levels compared to plasma and normal breast tissue. Previously, we reported intra-tumour E2 to be negatively correlated to transcription levels of 17β-HSD2 but positively correlated to 17β-HSD7. Here, we explored these mechanisms further by analysing the same breast tumours for 17β-HSD2 and -7 SNPs, as well as 17β-HSD7 gene copy number. Among the SNPs detected, we found the 17β-HSD2 rs4445895_T allele to be associated with lower intra-tumour mRNA (p=0.039) and an elevated intra-tumour E2 level (p=0.006). In contrast, we found the 17β-HSD7 rs1704754_C allele to be associated with elevated mRNA (p=0.050) but not to E2 levels in breast tumour tissue. Surprisingly, 17β-HSD7 - gene copy number was elevated in 19 out of 46 breast tumours examined. Elevated copy number was associated with an increased mRNA expression level (p=0.013) and elevated tumour E2 (p=0.025). Interestingly, elevated 17β-HSD7 - gene copy number was associated with increased expression not only of 17β-HSD7, but the 17β-HSD7_II pseudogene as well (p=0.019). Expression level of 17β-HSD7 and its pseudogene was significantly correlated both in tumour tissue (rs=0.457, p=0.001) and in normal tissue (rs=0.453, p=0.002). While in vitro transfection experiments revealed no direct impact of 17β-HSD7 expression on pseudogene level, the fact that 17β-HSD7 and 17β-HSD7_II share a 95.6% sequence identity suggests the two transcripts may be subject to common regulatory mechanisms. In conclusion, genetic variants of 17β-HSD2 and 17β-HSD7 may affect intra-tumour gene expression as well as breast cancer E2 levels in postmenopausal women.

Polymorphism Thr160Thr in SRD5A1, involved in the progesterone metabolism, modifies postmenopausal breast cancer risk associated with menopausal hormone therapy

Menopausal hormone therapy (MHT) is associated with an increased breast cancer risk in postmenopausal women, with combined estrogen-progestagen therapy posing a greater risk than estrogen monotherapy. However, few studies focused on potential effect modification of MHT-associated breast cancer risk by genetic polymorphisms in the progesterone metabolism. We assessed effect modification of MHT use by five coding single nucleotide polymorphisms (SNPs) in the progesterone metabolizing enzymes AKR1C3 (rs7741), AKR1C4 (rs3829125, rs17134592), and SRD5A1 (rs248793, rs3736316) using a two-center population-based case-control study from Germany with 2,502 postmenopausal breast cancer patients and 4,833 matched controls. An empirical-Bayes procedure that tests for interaction using a weighted combination of the prospective and the retrospective case-control estimators as well as standard prospective logistic regression were applied to assess multiplicative statistical interaction between polymorphisms and duration of MHT use with regard to breast cancer risk assuming a log-additive mode of inheritance. No genetic marginal effects were observed. Breast cancer risk associated with duration of combined therapy was significantly modified by SRD5A1_rs3736316, showing a reduced risk elevation in carriers of the minor allele (p (interaction,empirical-Bayes) = 0.006 using the empirical-Bayes method, p (interaction,logistic regression) = 0.013 using logistic regression). The risk associated with duration of use of monotherapy was increased by AKR1C3_rs7741 in minor allele carriers (p (interaction,empirical-Bayes) = 0.083, p (interaction,logistic regression) = 0.029) and decreased in minor allele carriers of two SNPs in AKR1C4 (rs3829125: p (interaction,empirical-Bayes) = 0.07, p (interaction,logistic regression) = 0.021; rs17134592: p (interaction,empirical-Bayes) = 0.101, p (interaction,logistic regression) = 0.038). After Bonferroni correction for multiple testing only SRD5A1_rs3736316 assessed using the empirical-Bayes method remained significant. Postmenopausal breast cancer risk associated with combined therapy may be modified by genetic variation in SRD5A1. Further well-powered studies are, however, required to replicate our finding.

Analysis of estrogens in serum and plasma from postmenopausal women: past present, and future

Previous studies have shown that the selection of women who are at high breast cancer risk for treatment with chemoprevention agents leads to an enhanced benefit/risk ratio. However, further efforts to implement this strategy will require the development of new models to predict the breast cancer risk of particular individuals. Postmenopausal women with elevated plasma or serum estrogens are at increased risk for breast cancer. Therefore, the roles of various enzymes involved in the biosynthesis of estrogens in postmenopausal women have been reviewed in detail. In addition, the potential genotoxic and/or proliferative effects of the different estrogen metabolites as risk factors in the etiology of breast cancer have been examined. Unfortunately, much of the current bioanalytical methodology employed for the analysis of plasma and serum estrogens has proved to be problematic. Major advances in risk assessment would be possible if reliable methodology were available to quantify estradiol and its major metabolites in the plasma or serum of postmenopausal women. High performance liquid chromatography (HPLC) coupled with radioimmunoassay (RIA) currently provides the most sensitive and best validated immunoassay method for the analysis of estrone and estradiol in serum samples from postmenopausal women. However, inter-individual differences in specificity observed with many other immunoassays have caused significant problems when interpreting epidemiologic studies of breast cancer. It is almost impossible to overcome the inherent assay problems involved in using RIA-based methodology, particularly for multiple estrogens. For reliable measurements of multiple estrogens in plasma or serum, it will be necessary to employ stable isotope dilution methodology in combination with liquid chromatography-tandem mass spectrometry (LC-MS/MS). Extremely high sensitivity can be obtained with pre-ionized estrogen derivatives when employed in combination with a modern triple quadrupole mass spectrometer and nanoflow LC. Using [(13)C(6)]-estrone as the internal standard it has proved possible to analyze estrone as its pre-ionized Girard T (GT) derivative in sub-fg (low amol) amounts on column. This suggests that in the future it will be possible to routinely conduct LC-MS assays of multiple estrogen metabolites in serum and plasma at even lower concentrations than the current lower limit of quantitation of 0.4pg/mL (1.6pmol/L). The ease with which the pre-ionization derivatization strategy can be implemented will make it possible to readily introduce high sensitivity stable isotope dilution methodology in laboratories that are currently employing LC-MS/MS methodology. This will help conserve important plasma and serum samples as it will be possible to conduct high sensitivity analyses using low sample volumes.