Colin D Clyne

Monash University (Australia), Melbourne, Victoria, Australia

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Publications (67)296.5 Total impact

  • [Show abstract] [Hide abstract]
    ABSTRACT: The mineralocorticoid receptor (MR) plays a central role in salt and water homeostasis via the kidney; however, inappropriate activation of the MR in the heart can lead to heart failure. A selective MR modulator that antagonizes MR signaling in the heart but not the kidney would provide the cardiovascular protection of current MR antagonists but allow for normal electrolyte balance. The development of such a pharmaceutical requires an understanding of coregulators and their tissue-selective interactions with the MR, which is currently limited by the small repertoire of MR coregulators described in the literature. To identify potential novel MR coregulators, we used T7 phage display to screen tissue-selective cDNA libraries for MR-interacting proteins. Thirty MR binding peptides were identified, from which three were chosen for further characterization based on their nuclear localization and their interaction with other MR-interacting proteins, or in the case of XRCC6, its known status as an androgen receptor coregulator. Eukaryotic elongation factor 1A1 (EEF1A1), structure-specific recognition protein 1 (SSRP1), and x-ray repair cross-complementing protein 6 (XRCC6) modulated MR-mediated transcription in a ligand-, cell- and/or promoter-specific manner, and co-localized with the MR upon agonist treatment when imaged using immunofluorescence microscopy. These results highlight the utility of phage display for rapid and sensitive screening of MR binding proteins, and suggest that EEF1A1, SSRP1 and XRCC6 may be potential MR coactivators whose activity is dependent on ligand, cellular context and target gene promoter.
    Molecular endocrinology (Baltimore, Md.). 07/2014;
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    ABSTRACT: The cytokine Tumor Necrosis Factor-α is critical to Estrogen Receptor positive breast cancer pathology, stimulating estrogen-biosynthesis pathways and preventing the differentiation of estrogen-producing fibroblasts. High concentrations of TNFα are detected in the tumor microenvironment, and infiltrating immune cells are thought to be a major source. This study identifies that TNFα is also a tumor-derived factor, expressed in ER+ tumour epithelial cells and regulated by 17-β-estradiol (E2). Treatment of MCF-7, T47D and ZR-75 breast cancer cells with E2 increased TNFα mRNA and protein expression and secretion. This effect was mitigated with the use of ERα inhibitors 4-hydroy-tamoxifen and ICI-182780, indicating that E2-mediated TNFα induction was via the actions of ERα. Chromatin immunoprecipitation reveals ERα binding to the TNFα promoter upon stimulation with E2. This study demonstrates for the first time a positive feedback loop between estradiol and TNFα, critical in maintaining high levels of the hormone within the ER+ breast tumour microenvironment.
    Molecular and Cellular Endocrinology 07/2014; · 4.04 Impact Factor
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    ABSTRACT: Nelumal A, the active principle of Ligularia nelumbifolia was preliminarily tested as an aromatase inhibitors in HEK293 cells transfected with aromatase cDNA and using anastrazole as the reference drug. This screening revealed that it showed an appreciable level of inhibition. Subsequent experiments aimed to evaluate the aromatase activity and expression in KGN cells confirmed that the title natural product, after an incubation of 48 h, compared favourably with anastrazole (1 microM) in the concentration range 10-30 microM. Moreover, nelumal A (30 microM) abolished the aromatase mRNA expression in the same cell line.
    Natural product communications 06/2014; 9(6):823-4. · 0.96 Impact Factor
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    ABSTRACT: Although molecular signatures based on transcript expression in breast cancer samples have provided new insights into breast cancer classification and prognosis, there are acknowledged limitations in current signatures. To provide rational, pathway-based signatures of disrupted physiology in cancer tissues that may be relevant to prognosis, this study has directly quantitated changed gene expression, between normal breast and cancer tissue, as a basis for signature development. The nuclear receptor (NR) family of transcription factors, and their coregulators, are fundamental regulators of every aspect of metazoan life, and were rigorously quantified in normal breast tissues and ERα positive and ERα negative breast cancers. Coregulator expression was highly correlated with that of selected NR in normal breast, particularly from postmenopausal women. These associations were markedly decreased in breast cancer, and the expression of the majority of coregulators was down-regulated in cancer tissues compared with normal. While in cancer the loss of NR-coregulator associations observed in normal breast was common, a small number of NR (Rev-ERBβ, GR, NOR1, LRH-1 and PGR) acquired new associations with coregulators in cancer tissues. Elevated expression of these NR in cancers was associated with poorer outcome in large clinical cohorts, as well as suggesting the activation of ERα -related, but ERα-independent, pathways in ERα negative cancers. In addition, the combined expression of small numbers of NR and coregulators in breast cancer was identified as a signature predicting outcome in ERα negative breast cancer patients, not linked to proliferation and with predictive power superior to existing signatures containing many more genes. These findings highlight the power of predictive signatures derived from the quantitative determination of altered gene expression between normal breast and breast cancers. Taken together, the findings of this study identify networks of NR-coregulator associations active in normal breast but disrupted in breast cancer, and moreover provide evidence that signatures based on NR networks disrupted in cancer can provide important prognostic information in breast cancer patients.
    Molecular oncology 04/2014; · 6.70 Impact Factor
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    ABSTRACT: Liver Receptor Homolog-1 (LRH-1) is an orphan nuclear receptor that belongs to the NR5A subgroup of nuclear receptors. LRH-1 induces key genes to regulate metabolic process, ovarian function, cancer cell proliferation and steroidogenesis. In the breast, LRH-1 modulates and synergizes with endogenous estrogen signalling to promote breast cancer cell proliferation. We used siRNA knockdown strategies in order to deplete LRH-1 in breast cancer cells and followed with microarray analysis to identify LRH-1 dependent mechanisms. We identified key genes involved in TGF-β signalling to be highly responsive to LRH-1 knockdown. This relationship was validated in two breast cancer cell lines over-expressing LRH-1 in vitro and in a novel transgenic mouse with targeted LRH-1 over-expression in mammary epithelial cells. Notably, TGF-β signalling was activated in LRH-1 over expressing breast cancer cells and mouse mammary glands. Further analyses of mammary gross morphology revealed a significant reduction in mammary lateral budding after LRH-1 over expression. These findings suggest that the altered mammary morphogenesis in LRH-1 transgenic animals is mediated via enhanced TGF-β expression. The regulation of TGF-β isoforms and SMAD2/3-mediated downstream signalling by LRH-1 also implicates a potential contribution of LRH-1 in breast cancer. Collectively this data demonstrates that LRH-1 regulates TGF-β expression and downstream signalling in mouse mammary glands.
    Endocrinology 02/2014; · 4.72 Impact Factor
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    ABSTRACT: The heritable component of breast cancer accounts for only a small proportion of total incidences. Environmental and lifestyle factors are therefore considered one of the major influencing components increasing breast cancer risk. Endocrine disrupting chemicals (EDCs) are ubiquitous in the environment. The estrogenic property of EDCs has thus seen many associations between ongoing exposures and the development of endocrine-related diseases, including breast cancer. The environment consists of a heterogenous population of EDCs and despite many identified modes of action, including that of altering the epigenome, drawing definitive correlations to breast cancer has been a point of much discussion. In this review we describe in detail well characterised EDCs and their actions in the environment; their ability to disrupt mammary gland formation in animal and human experimental models; and their associations with exposure and breast cancer risk. We also highlight the susceptibility of early-life exposure of each EDC to mediate epigenetic alterations, and where possible describe how these epigenome changes influence breast cancer risk.
    Endocrine Related Cancer 02/2014; · 5.26 Impact Factor
  • Breast Cancer Research and Treatment 01/2014; · 4.47 Impact Factor
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    ABSTRACT: Estrogens are known to play a role in modulating metabolic processes within the body. The Aromatase knockout (ArKO) mice have been shown to harbor factors of Metabolic syndrome with central adiposity, hyperinsulinemia and male-specific hepatic steatosis. To determine the effects of estrogen ablation and subsequent replacement in males on whole body glucose metabolism, three- and six-month-old male ArKO mice were subjected to whole body glucose, insulin and pyruvate tolerance tests and analyzed for ensuing metabolic changes in liver, adipose tissue, and skeletal muscle. Estrogen-deficient male ArKO mice showed increased gonadal adiposity which was significantly reduced upon 17β-estradiol (E2) treatment. Concurrently, elevated ArKO serum leptin levels were significantly reduced upon E2 treatment and lowered serum adiponectin levels were restored to wild type levels. Three-month-old male ArKO mice were hyperglycemic, and both glucose and pyruvate intolerant. These phenotypes continued through to 6 months of age, highlighting a loss of glycemic control. ArKO livers displayed changes in gluconeogenic enzyme expression, and in insulin signaling pathways upon E2 treatment. Liver triglycerides were increased in the ArKO males only after 6 months of age, which could be reversed by E2 treatment. No differences were observed in insulin-stimulated ex vivo muscle glucose uptake nor changes in ArKO adipose tissue and muscle insulin signaling pathways. Therefore, we conclude that male ArKO mice develop hepatic glucose intolerance by the age of 3 months which precedes the sex-specific development of hepatic steatosis. This can be reversed upon the administration of exogenous E2.
    PLoS ONE 01/2014; 9(2):e87230. · 3.53 Impact Factor
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    ABSTRACT: Although molecular signatures based on transcript expression in breast cancer samples have provided new insights into breast cancer classification and prognosis, there are acknowledged limitations in current signatures. To provide rational, pathway-based signatures of disrupted physiology in cancer tissues that may be relevant to prognosis, this study has directly quantitated changed gene expression, between normal breast and cancer tissue, as a basis for signature development. The nuclear receptor (NR) family of transcription factors, and their coregulators, are fundamental regulators of every aspect of metazoan life, and were rigorously quantified in normal breast tissues and ERα positive and ERα negative breast cancers. Coregulator expression was highly correlated with that of selected NR in normal breast, particularly from postmenopausal women. These associations were markedly decreased in breast cancer, and the expression of the majority of coregulators was down-regulated in cancer tissues compared with normal. While in cancer the loss of NR-coregulator associations observed in normal breast was common, a small number of NR (Rev-ERBβ, GR, NOR1, LRH-1 and PGR) acquired new associations with coregulators in cancer tissues. Elevated expression of these NR in cancers was associated with poorer outcome in large clinical cohorts, as well as suggesting the activation of ERα -related, but ERα -independent, pathways in ERα negative cancers. In addition, the combined expression of small numbers of NR and coregulators in breast cancer was identified as a signature predicting outcome in ERα negative breast cancer patients, not linked to proliferation and with predictive power superior to existing signatures containing many more genes. These findings highlight the power of predictive signatures derived from the quantitative determination of altered gene expression between normal breast and breast cancers. Taken together, the findings of this study identify networks of NR-coregulator associations active in normal breast but disrupted in breast cancer, and moreover provide evidence that signatures based on NR networks disrupted in cancer can provide important prognostic information in breast cancer patients.
    Molecular Oncology 01/2014; · 6.70 Impact Factor
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    ABSTRACT: The interaction between breast tumor epithelial and stromal cells is vital for initial and recurrent tumor growth. While breast cancer-associated stromal cells provide a favorable environment for proliferation and metastasis, the molecular mechanisms contributing to this process are not fully understood. Nuclear receptors (NRs) are intracellular transcription factors that directly regulate gene expression. Little is known about the status of NRs in cancer-associated stroma. Nuclear Receptor Low-Density Taqman Arrays were used to compare the gene expression profiles of all 48 NR family members in a collection of primary cultured cancer-associated fibroblasts (CAFs) obtained from estrogen receptor (ER)α positive breast cancers (n = 9) and normal breast adipose fibroblasts (NAFs) (n = 7). Thirty-three of 48 NRs were expressed in both the groups, while 11 NRs were not detected in either. Three NRs (dosage-sensitive sex reversal, adrenal hypoplasia critical region, on chromosome X, gene 1 (DAX-1); estrogen-related receptor beta (ERR-β); and RAR-related orphan receptor beta (ROR-β)) were only detected in NAFs, while one NR (liver receptor homolog-1 (LRH-1)) was unique to CAFs. Of the NRs co-expressed, four were significantly down-regulated in CAFs compared with NAFs (RAR-related orphan receptor-α (ROR-α); Thyroid hormone receptor-β (TR-β); vitamin D receptor (VDR); and peroxisome proliferator-activated receptor-γ (PPAR-γ)). Quantitative immunohistochemistry for LRH-1, TR-β, and PPAR-γ proteins in stromal fibroblasts from an independent panel of breast cancers (ER-positive (n = 15), ER-negative (n = 15), normal (n = 14)) positively correlated with mRNA expression profiles. The differentially expressed NRs identified in tumor stroma are key mediators in aromatase regulation and subsequent estrogen production. Our findings reveal a distinct pattern of NR expression that therefore fits with a sustained and increased local estrogen microenvironment in ER-positive tumors. NRs in CAFs may provide a new avenue for the development of intratumoral-targeted therapies in breast cancer.
    Breast Cancer Research and Treatment 10/2013; · 4.47 Impact Factor
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    ABSTRACT: The present study aims to determine the estrogenicity of Millettia macrophylla, a Cameroonian medicinal plant, in ovariectomized rats and to investigate the underlying mechanisms, in order to justify scientifically its traditional use. To accomplish this objective, we used dichloromethane (DCM) and methanol (MeOH) extracts of the stem bark of M. macrophylla. In the cell culture based assay, the MeOH extract significantly transactivated estrogen receptor α (ERα) and estrogen receptor β (ERβ); in addition, the estrogen-like effects of both, DCM and MeOH extracts, could be inhibited in vitro by the pure ER antagonist ICI 182,780, indicating that these effects were primarily mediated through ERs. In animal experiments, both DCM and MeOH extracts significantly increased the uterine and vaginal epithelial heights in the 3-day treatment assay, while only the MeOH extract exhibited such effects in the sub-chronic treatment regimen. Furthermore, the MeOH extract significantly decreased fasting serum triglycerides, total cholesterol levels and artherogenic risk in the sub-chronic treatment. These results indicate that M. macrophylla extracts have estrogen-like effects supporting their traditional use in Cameroon to alleviate some menopausal problems (See graphical abstract in Supplementary Fig. 1, available in the online version only).
    Journal of Pharmacological Sciences 09/2013; · 2.15 Impact Factor
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    ABSTRACT: The present study aims to determine the estrogenicity of Millettia macrophylla , a Cameroonian medicinal plant, in ovariectomized rats and to investigate the underlying mecha -nisms, in order to justify scientifically its traditional use. To accomplish this objective, we used dichloromethane (DCM) and methanol (MeOH) extracts of the stem bark of M. macrophylla. In the cell culture based assay, the MeOH extract significantly transactivated estrogen receptor a (ER a) and estrogen receptor b (ER b); in addition, the estrogen-like effects of both, DCM and MeOH extracts, could be inhibited in vitro by the pure ER antagonist ICI 182,780, indicating that these effects were primarily mediated through ERs. In animal experiments, both DCM and MeOH extracts significantly increased the uterine and vaginal epithelial heights in the 3-day treatment assay, while only the MeOH extract exhibited such effects in the sub-chronic treatment regimen. Furthermore, the MeOH extract significantly decreased fasting serum triglycerides, total cholesterol levels and artherogenic risk in the sub-chronic treatment. These results indicate that M. macrophylla extracts have estrogen-like effects supporting their traditional use in Cameroon to alleviate some menopausal problems (See graphical abstract in Supplementary Fig. 1, available in the online version only).
    Journal of Pharmacological Sciences 09/2013; 123:120 – 131. · 2.15 Impact Factor
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    ABSTRACT: The expression of orphan nuclear receptor Liver Receptor Homolog-1 (LRH-1) is elevated in breast cancer and promotes proliferation, migration and invasion in vitro. LRH-1 expression is regulated by oestrogen (E2), with LRH-1 mRNA transcript levels higher in oestrogen receptor α (ERα) positive (ER+) breast cancer cells compared to ER- cells. However, the presence of LRH-1 protein in ER- cells suggests discordance between mRNA transcript levels and protein expression. To understand this, we investigated the impact of mRNA and protein stability in determining LRH-1 protein levels in breast cancer cells. LRH-1 transcript levels were significantly higher in ER+ versus ER- breast cancer cells lines; however LRH-1 protein was expressed at similar levels. We found LRH-1 mRNA and protein was more stable in ER- compared to ER+ cell lines. The tumour-specific LRH-1 variant isoform, LRH-1v4, which is highly responsive to E2, showed increased mRNA stability in ER- versus ER+ cells. In addition, in MCF-7 and T47-D cell lines, LRH-1 total mRNA stability was reduced with E2 treatment, this effect mediated by ERα. Our data demonstrates that in ER- cells, increased mRNA and protein stability contribute to the abundant protein expression levels. Expression and immunolocalisation of LRH-1 in ER- cells as well as ER- tumours suggests a possible role in the development of ER- tumors. The modulation of LRH-1 bioactivity may therefore be beneficial as a treatment option in both ER- and ER+ breast cancer.
    Biochemical and Biophysical Research Communications 08/2013; · 2.28 Impact Factor
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    ABSTRACT: Granulosa cell tumours of the ovary (GCT) express aromatase and produce oestrogens. The ovarian-specific aromatase promoter (pII) is regulated by members of the group 5A nuclear receptor family, SF-1 and LRH-1. Since both SF-1 and LRH-1 are implicated in proliferation and cancer, we hypothesised that alteration in the expression of either or both receptors may be associated with GCT. We therefore determined the expression of LRH-1, SF-1 and aromatase in a cohort of GCT, mucinous and serous cystadenocarcinomas, and normal ovaries. LRH-1 mRNA was present at low level in normal ovary and serous cystadenocarcinoma, but was elevated approximately 30-fold in GCT, and 8-fold in mucinous cystadenocarcinoma, compared to normal ovary. LRH-1 protein expression was confirmed in GCT by immunohistochemistry. SF-1 mRNA was significantly lower that of LRH-1 in all samples and not significantly altered in GCT, compared to normal ovary. Aromatase mRNA was present at low level in normal ovary and serous and mucinous cystadenocarcinoma, and significantly elevated (18-fold) in GCT compared to normal ovary. Despite the coordinate over-expression of both LRH-1 and aromatase in GCT versus normal ovary, their levels did not correlate in individual patients; rather, aromatase expression correlated with that of SF-1. Finally, although both LRH-1 and SF-1 activated aromatase promoter activity in transient transfection studies, gel-shift and chromatin immunoprecipitation data indicated that SF-1, but not LRH-1, bound to the aromatase promoter. We conclude that SF-1 regulates aromatase expression in GCT; over-expression of LRH-1 suggests that this receptor may be involved in the pathogenesis of GCT by mechanisms other than the regulation of aromatase. Its role in this disease therefore warrants further investigation.
    Steroids 03/2013; · 2.80 Impact Factor
  • Sarah Q To, Kevin C Knower, Colin D Clyne
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    ABSTRACT: Tumor necrosis factor α (TNFα) has many roles in both physiological and pathological states. Initially thought to cause necrosis of tumors, research has shown that in many tumor types, including breast cancer, TNFα contributes to growth and proliferation. The presence of TNFα-derived from the tumor and infiltrating immune cells-within a breast tumor microenvironment has been correlated with a more aggressive phenotype, and the postmenopausal ER+ subtype of breast cancers appears to strongly respond to its many pro-growth signaling functions. We discuss how TNFα regulates estrogen biosynthesis within the breast, affecting the activity of the key estrogen-synthesizing enzymes aromatase, estrone sulfatase, and 17β-HSD type 1. Additionally, we describe the anti-adipogenic actions of TNFα that are critical in preventing adjacent estrogen-producing adipose fibroblasts from differentiating, ensuring that the tumor maintains a constant source of estrogen-producing cells. We examine how the increased risk of developing breast cancer in older and obese individuals may be linked to the levels of TNFα in the body. Finally, we evaluate the feasibility of targeting TNFα and its associated pathways as a novel approach to breast cancer therapeutics.
    Journal of interferon & cytokine research: the official journal of the International Society for Interferon and Cytokine Research 03/2013; · 1.63 Impact Factor
  • Sarah Q To, Kevin C Knower, Colin D Clyne
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    ABSTRACT: The Early Growth Response genes EGR2 and EGR3 play an important role in mediating TNFα induced aromatase expression via the adipose specific promoter PI.4. The upstream signaling pathway stimulated by TNFα to initiate this is unknown. The aim of this present study was to determine the signaling pathways activated by TNFα which result in EGR2 and EGR3 transcription, and ultimately activation of PI.4. The NFκB inhibitor BAY-11-7082 dose-dependently inhibited transcription of EGR2 and EGR3 mRNA as well as total and PI.4-specific CYP19A1 mRNA. The MAPK pathway inhibitor U0126, inhibitor of MEK1/2 had the same effect, however inhibition of c-Jun and JNK1,2,3 with SP600125 did not lead to down-regulation. We provide evidence for the first time that EGR2 and EGR3 are regulated by NFκB and MAPK signalling pathways downstream of TNFα stimulation in breast adipose fibroblasts, and that this in turn is upstream of CYP19A1 transcription via PI.4.
    Biochemical and Biophysical Research Communications 02/2013; · 2.28 Impact Factor
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    ABSTRACT: Expression of the oestrogen producing enzyme, aromatase, is regulated in a tissue-specific manner by its encoding gene CYP19A1. In post-menopausal women, the major site for oestrogen production in the breast is the adipose, where CYP19A1 transcription is driven by the distal promoter I.4 (PI.4). Transcripts via this promoter are also elevated in breast adipose fibroblasts (BAFs) adjacent to a tumour. PI.4 expression is stimulated by a number of cytokines, and TNFα is one such factor. The transcriptional mechanisms induced by TNFα to stimulate PI.4 are poorly characterised. We show that the early growth response (Egr) transcription factors play an important role in the TNFα-induced signalling pathway resulting in elevated PI.4 transcription. TNFα treatment of BAFs increases mRNA levels of all four Egr family members, with EGR2 being the most highly expressed. Overexpression of EGR2 causes an increase in endogenous CYP19A1 expression in preadipocyte Simpson-Golabi-Behmel syndrome cells, driven by increases in PI.4-specific transcripts. PI.4 luciferase reporter activity is increased in a dose-dependent manner by EGR2, EGR3 and EGR4, with EGR2 showing the most potent activation of promoter activity. Deletion analysis indicates that this promoter activity is being indirectly mediated by a short region of the promoter not containing any previously characterised binding sites, and we further show that EGR2 does not bind directly or indirectly to this promoter region. However, siRNA knockdown of the Egrs reduces the total and PI.4-derived CYP19A1 transcription in BAFs. These studies unveil a novel component of the aromatase gene regulatory network and further enhance the complexity of oestrogen production in the breast.
    Breast Cancer Research and Treatment 01/2013; · 4.47 Impact Factor
  • Kevin C Knower, Sarah Q To, Colin D Clyne
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    ABSTRACT: Epigenome changes have been widely demonstrated to contribute to the initiation and progression of a vast array of cancers including breast cancer. The reversible process of many epigenetic modifications is thus an attractive feature for the development of novel therapeutic measures. In oestrogen receptor α (hereinafter referred to as ER) positive tumours, endocrine therapies have proven beneficial in patient care, particularly in postmenopausal women where two-thirds of tumours are oestrogen dependent. However, resistance to such therapies is a common feature amongst individuals. In the current review, we discuss the influence that epigenetics has on oestrogen dependent breast cancers, in particular (i) the production of intracrine oestrogen in postmenopausal women (ii) the action of oestrogen on epigenetic processes and (iii) the links between epigenetics and endocrine resistance and the current advancements in epigenetic therapy that target this process.
    The Journal of steroid biochemistry and molecular biology 01/2013; · 3.98 Impact Factor
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    ABSTRACT: To identify biologically relevant groupings or clusters of nuclear receptors (NR) that are associated with breast neoplasia, with potentially diagnostic, discriminant or prognostic value, we quantitated mRNA expression levels of all 48 members of the human NR superfamily by TaqMan low-density array analysis in 116 curated breast tissue samples, including pre- and postmenopausal normal breast and both ERα(+) and ERα(-) tumor tissue. In addition, we have determined NR levels in independent cohorts of tamoxifen-treated ERα(+) and ERα(-) tissue samples. There were differences in relative NR mRNA expression between neoplastic and normal breast, and between ER(+) and ER(-) tumors. First, there is overexpression of the NUR77 subgroup and EAR2 in neoplastic breast. Second, we identify a signature of five NR (ERα, EAR2, NUR77, TRα, and RARγ) that classifies breast samples with more than 97% cross-validated accuracy into normal or cancer classes. Third, we find a novel negative association between five NR (TRβ, NUR77, RORγ, COUP-TFII, and LRH1) and histological grade. Finally, four NR (COUP-TFII, TRβ, PPARγ, and MR) are significant predictors of metastasis-free survival in tamoxifen-treated breast cancers, independent of ER expression. The present study highlights the discriminant and prognostic value of NR in breast cancer; identifies novel, clinically relevant, NR signatures; and highlights NR signaling pathways with potential roles in breast cancer pathophysiology and as new therapeutic targets.
    Molecular Endocrinology 01/2013; · 4.75 Impact Factor
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    ABSTRACT: The increase in local oestrogen production seen in oestrogen receptor positive (ER+) breast cancers is driven by increased activity of the aromatase enzyme. CYP19A1, the encoding gene for aromatase, is often overexpressed in the oestrogen-producing cells of the breast adipose fibroblasts (BAFs) surrounding an ER+ tumour, and the molecular processes underlying this upregulation is important in the development of breast-specific aromatase inhibitors for breast cancer therapy. Prostaglandin E2 (PGE2), a factor secreted by tumours, is known to stimulate CYP19A1 expression in human BAFs. The hormonal regulation of this process has been examined; however, what is less well understood is the emerging role of epigenetic mechanisms and how they modulate PGE2 signalling. This present study characterises the epigenetic processes underlying expression of the prostanoid receptor EP2 in the context of ER+ breast cancer. Sodium bisulphite sequencing of CpG methylation within the promoter region of EP2 revealed that an inverse correlation existed between methylation levels and relative EP2 expression in breast cancer cell lines MDA-MB-231, MCF7 and MCF10A but not in HS578t and T47D. Inhibition of DNA methylation with 5-aza-2'-deoxycytidine (5aza) and histone deacetylation with Trichostatin A (TSA) resulted in upregulation of EP2 mRNA in all cell lines with varying influences of each epigenetic process observed. Expression of EP2 was detected in human BAFs despite a natively methylated promoter, and this expression was further increased upon 5aza treatment. An examination of 3 triple negative, 3 ductal carcinoma in situ and 3 invasive ductal carcinoma samples revealed that there was no change in EP2 promoter methylation status between normal and cancer associated stroma, despite observed differences in relative mRNA levels. Although EP2 methylation status is inversely correlated to expression levels in established breast cancer cell lines, we could not identify that such a correlation existed in tumour-associated stroma cells.
    The Journal of steroid biochemistry and molecular biology 08/2012; 132(3-5):331-8. · 3.98 Impact Factor

Publication Stats

2k Citations
296.50 Total Impact Points

Institutions

  • 2002–2014
    • Monash University (Australia)
      • Department of Biochemistry and Molecular Biology
      Melbourne, Victoria, Australia
    • Prince Henry's Institute
      • Laboratory of Cancer Drug Discovery
      Melbourne, Victoria, Australia
  • 2013
    • Swinburne University of Technology
      Melbourne, Victoria, Australia
  • 2006
    • Duke University Medical Center
      • Department of Pharmacology and Cancer Biology
      Durham, NC, United States
  • 2004
    • Università della Calabria
      • Department of Pharmaco-Biology
      Rende, Calabria, Italy
  • 1995–2002
    • University of Texas Southwestern Medical Center
      • Department of Obstetrics and Gynecology
      Dallas, TX, United States
  • 1996
    • University of Texas at Dallas
      Richardson, Texas, United States