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Cai Q, Tian X, Tang Y, Cong H, Liu J, Zhao S, Ma R, Wang J, Zhu J. Association between prolactin/testosterone ratio and breast cancer in Chinese women. Chin Med J (Engl) 2024; 137:368-370. [PMID: 38200638 PMCID: PMC10836897 DOI: 10.1097/cm9.0000000000002942] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2023] [Indexed: 01/12/2024] Open
Affiliation(s)
- Qian Cai
- Department of Geriatric Medicine, Qilu Hospital of Shandong University, Jinan, Shandong 250012, China
- Key Laboratory of Cardiovascular Proteomics of Shandong Province, Qilu Hospital of Shandong University, Jinan, Shandong 250012, China
- Department of Pharmacology, School of Basic Medical Sciences, Shandong University, Jinan, Shandong 250012, China
| | - Xiaohan Tian
- Department of Breast Surgery, General Surgery, Qilu Hospital of Shandong University, Jinan, Shandong 250012, China
| | - Yuyi Tang
- Department of Thyroid and Breast Surgery, Guangdong Second Provincial General Hospital, Guangzhou, Guangdong 510310, China
| | - Han Cong
- Department of Toxicology and Cancer Biology, Collage of Medicine, University of Kentucky, Lexington, KY 40536, USA
| | - Jie Liu
- Department of Breast Surgery, General Surgery, Qilu Hospital of Shandong University, Jinan, Shandong 250012, China
| | - Song Zhao
- Department of Breast Surgery, General Surgery, Qilu Hospital of Shandong University, Jinan, Shandong 250012, China
- Department of Immunology, School of Basic Medical Science, Shandong University, Jinan, Shandong 250012, China
| | - Rong Ma
- Department of Breast Surgery, General Surgery, Qilu Hospital of Shandong University, Jinan, Shandong 250012, China
| | - Jianli Wang
- Department of Gynaecology and Obstetrics, Qilu Hospital of Shandong University, Jinan, Shandong 250012, China
| | - Jiang Zhu
- Department of Breast Surgery, General Surgery, Qilu Hospital of Shandong University, Jinan, Shandong 250012, China
- Department of Immunology, School of Basic Medical Science, Shandong University, Jinan, Shandong 250012, China
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Abstract
While it has been known for decades that androgen hormones influence normal breast development and breast carcinogenesis, the underlying mechanisms have only been recently elucidated. To date, most studies have focused on androgen action in breast cancer cell lines, yet these studies represent artificial systems that often do not faithfully replicate/recapitulate the cellular, molecular and hormonal environments of breast tumours in vivo. It is critical to have a better understanding of how androgens act in the normal mammary gland as well as in in vivo systems that maintain a relevant tumour microenvironment to gain insights into the role of androgens in the modulation of breast cancer development. This in turn will facilitate application of androgen-modulation therapy in breast cancer. This is particularly relevant as current clinical trials focus on inhibiting androgen action as breast cancer therapy but, depending on the steroid receptor profile of the tumour, certain individuals may be better served by selectively stimulating androgen action. Androgen receptor (AR) protein is primarily expressed by the hormone-sensing compartment of normal breast epithelium, commonly referred to as oestrogen receptor alpha (ERa (ESR1))-positive breast epithelial cells, which also express progesterone receptors (PRs) and prolactin receptors and exert powerful developmental influences on adjacent breast epithelial cells. Recent lineage-tracing studies, particularly those focussed on NOTCH signalling, and genetic analysis of cancer risk in the normal breast highlight how signalling via the hormone-sensing compartment can influence normal breast development and breast cancer susceptibility. This provides an impetus to focus on the relationship between androgens, AR and NOTCH signalling and the crosstalk between ERa and PR signalling in the hormone-sensing component of breast epithelium in order to unravel the mechanisms behind the ability of androgens to modulate breast cancer initiation and growth.
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Affiliation(s)
- Gerard A Tarulli
- Dame Roma Mitchell Cancer Research Laboratories (DRMCRL)Faculty of Health Sciences, School of Medicine, The University of Adelaide, Adelaide, South Australia 5005, Australia
| | - Lisa M Butler
- Dame Roma Mitchell Cancer Research Laboratories (DRMCRL)Faculty of Health Sciences, School of Medicine, The University of Adelaide, Adelaide, South Australia 5005, Australia
| | - Wayne D Tilley
- Dame Roma Mitchell Cancer Research Laboratories (DRMCRL)Faculty of Health Sciences, School of Medicine, The University of Adelaide, Adelaide, South Australia 5005, Australia
| | - Theresa E Hickey
- Dame Roma Mitchell Cancer Research Laboratories (DRMCRL)Faculty of Health Sciences, School of Medicine, The University of Adelaide, Adelaide, South Australia 5005, Australia
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Wang X, Kaplan DL. Hormone-responsive 3D multicellular culture model of human breast tissue. Biomaterials 2012; 33:3411-20. [PMID: 22309836 DOI: 10.1016/j.biomaterials.2012.01.011] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2011] [Accepted: 01/05/2012] [Indexed: 12/28/2022]
Abstract
A hormone-responsive 3D human tissue-like culture system was developed in which human primary mammary epithelial cells (MECs) were co-cultured with two types of predominant mammary stromal cells on silk protein scaffolds. Silk porous scaffolds with incorporated extracellular matrix provided a compatible environment for epithelial structure morphogenesis and differentiation. The presence of stromal cells promoted MEC proliferation, induced both alveolar and ductal morphogenesis and enhanced casein expression. In contrast, only alveolar structures were observed in monocultures. The alveolar structures generated from the heterotypic cultures in vitro exhibited proper polarity similar to human breast tissue in vivo. Consistent with their phenotypic appearance, more functional differentiation of epithelial cells was also observed in the heterotypic cultures, where casein-α and -β mRNA expression were increased significantly. Additionally, this 3D multicellular culture model displayed an estrogen-responsive physiologically relevant response, evidenced by enhanced cell proliferation, aberrant morphology, changes in gene expression profile and few polarized lumen structures after estrogen treatment. This culture system offers an excellent opportunity to explore the role of cell-cell and cell-substrate interactions during mammary gland development, the consequences of hormone receptor activation on MEC behavior and morphogenesis, as well as their alteration during neoplastic transformation in human breast tissue.
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Affiliation(s)
- Xiuli Wang
- Biomedical Engineering Department, Tufts University, Medford, MA 02155, USA
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Wiebe JP, Beausoleil M, Zhang G, Cialacu V. Opposing actions of the progesterone metabolites, 5alpha-dihydroprogesterone (5alphaP) and 3alpha-dihydroprogesterone (3alphaHP) on mitosis, apoptosis, and expression of Bcl-2, Bax and p21 in human breast cell lines. J Steroid Biochem Mol Biol 2010; 118:125-32. [PMID: 19931389 DOI: 10.1016/j.jsbmb.2009.11.005] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/03/2009] [Revised: 11/10/2009] [Accepted: 11/11/2009] [Indexed: 12/13/2022]
Abstract
Previous studies have shown that breast tissues and breast cell lines convert progesterone (P) to 5alpha-dihydroprogesterone (5alphaP) and 3alpha-dihydroprogesterone (3alphaHP) and that 3alphaHP suppresses, whereas 5alphaP promotes, cell proliferation and detachment. The objectives of the current studies were to determine if the 5alphaP- and 3alphaHP-induced changes in cell numbers are due to altered rates of mitosis and/or apoptosis, and if 3alphaHP and 5alphaP act on tumorigenic and non-tumorigenic cells, regardless of estrogen (E) and P receptor status. The studies were conducted on tumorigenic (MCF-7, MDA-MB-231, T47D) and non-tumorigenic (MCF-10A) human breast cell lines, employing several methods to assess the effects of the hormones on cell proliferation, mitosis, apoptosis and expression of Bcl-2, Bax and p21. In all four cell lines, 5alphaP increased, whereas 3alphaHP decreased cell numbers, [(3)H]thymidine uptake and mitotic index. Apoptosis was stimulated by 3alphaHP and suppressed by 5alphaP. 5alphaP resulted in increases in Bcl-2/Bax ratio, indicating decreased apoptosis; 3alphaHP resulted in decreases in Bcl-2/Bax ratio, indicating increased apoptosis. The effects of either 3alphaHP or 5alphaP on cell numbers, [(3)H]thymidine uptake, mitosis, apoptosis, and Bcl-2/Bax ratio, were abrogated when cells were treated simultaneously with both hormones. The expression of p21 was increased by 3alphaHP, and was unaffected by 5alphaP. The results provide the first evidence that 5alphaP stimulates mitosis and suppresses apoptosis, whereas 3alphaHP inhibits mitosis and stimulates apoptosis. The opposing effects of 5alphaP and 3alphaHP were observed in all four breast cell lines examined and the data suggest that all breast cancers (estrogen-responsive and unresponsive) might be suppressed by blocking 5alphaP formation and/or increasing 3alphaHP. The findings further support the hypothesis that progesterone metabolites are key regulatory hormones and that changes in their relative concentrations in the breast microenvironment determine whether breast tissues remain normal or become cancerous.
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Affiliation(s)
- John P Wiebe
- Department of Biology, University of Western Ontario, London, Ontario, Canada.
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Wang LS, Huang YW, Liu S, Yan P, Lin YC. Conjugated linoleic acid induces apoptosis through estrogen receptor alpha in human breast tissue. BMC Cancer 2008; 8:208. [PMID: 18652667 PMCID: PMC2517598 DOI: 10.1186/1471-2407-8-208] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2008] [Accepted: 07/24/2008] [Indexed: 12/21/2022] Open
Abstract
Background Conjugated linoleic acid (CLA), a naturally occurring fatty acid found in ruminant products such as milk and beef, has been shown to possess anti-cancer activities in in vivo animal models and in vitro cell culture systems. In human breast cancer, the overall duration of estrogen exposure is the most important risk factor for developing estrogen-responsive breast cancer. Accordingly, it has been suggested that estrogen exposure reduces apoptosis through the up-regulation of the anti-apoptosis protein, Bcl-2. Bcl-2, an anti-apoptotic protein, regulates apoptosis and plays a crucial role in the development and growth regulation of normal and cancerous cells. Our research interest is to examine the effects of CLA on the induction of apoptosis in human breast tissues. Methods The localization of Bcl-2 in both normal and cancerous human breast tissues was determined by immunohistochemical staining and the Bcl-2 protein expression was tested by western blot analysis. Co-culture of epithelial cells and stromal cells was carried out in the presence or absence of CLA to evaluate apoptosis in the context of a cell-cell interaction. Results The results showed that both normal and cancerous breast tissues were positive for Bcl-2 staining, which was higher overall in mammary ducts but very low in the surrounding stromal compartment. Interestingly, by quantifying the western blot data, basal Bcl-2 protein levels were higher in normal breast epithelial cells than in cancerous epithelial cells. Furthermore, treatment with 17β-estradiol (E2) stimulated growth and up-regulated Bcl-2 expression in estrogen responsive breast epithelial cells; however, these carcinogenic effects were diminished by either CLA or 4-Hydroxytamoxifen (Tam) and were suppressed further by the combination of CLA and Tam. In both one cell type cultured and co-culture systems, CLA induced cell apoptosis in ERα transfected MDA-MB-231 cells but not in the wild type MDA-MB-231 cells. Conclusion These data, therefore, demonstrate that ERα plays important roles in CLA induced apoptosis in human breast tissues.
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Affiliation(s)
- Li-Shu Wang
- Department of Veterinary Biosciences, College of Veterinary Medicine, The Ohio State University, Columbus, OH 43210, USA.
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Tsukahara S, Hojo R, Kuroda Y, Fujimaki H. Estrogen modulates Bcl-2 family protein expression in the sexually dimorphic nucleus of the preoptic area of postnatal rats. Neurosci Lett 2007; 432:58-63. [PMID: 18164816 DOI: 10.1016/j.neulet.2007.12.006] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2007] [Revised: 12/02/2007] [Accepted: 12/04/2007] [Indexed: 11/15/2022]
Abstract
In the sexually dimorphic nucleus of the preoptic area (SDN-POA) of postnatal rats, apoptotic cells are detected more frequently in females than males. This sex difference is under the influence of aromatized androgen. We have reported that there are sex differences in the levels of Bcl-2 (female<male) and Bax (female>male) in the central division of the medial preoptic nucleus (MPNc), a significant component of the SDN-POA, followed by a sex difference in induction of apoptosis via caspase-3 activation (female>male). In the present study, we examined effects of estradiol benzoate (EB) on expression of Bcl-2 and Bax in the MPNc. Female rats were subcutaneously injected with EB (25 or 50 microg per head) on postnatal day 5. MPNc and caudate putamen (CP) tissues were obtained from EB-treated female and male rats on postnatal day 6. Protein levels of Bcl-2 and Bax were determined by Western blotting. In the MPNc of female rats, EB at a dose of 50 microg/head but not 25 microg/head significantly increased Bcl-2 protein level and decreased Bax protein level. The levels of Bcl-2 and Bax of female rats treated with 50 microg of EB were comparable to those of male rats. However, the protein levels of Bcl-2 and Bax in the CP did not change with EB treatment. These results suggest that estrogen up-regulates Bcl-2 expression and down-regulates Bax expression in the MPNc of postnatal rats. Effects of estrogen on the Bcl-2 family are presumably responsible for sex difference in postnatal apoptosis of the SDN-POA.
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Affiliation(s)
- Shinji Tsukahara
- Research Center for Environmental Risk, National Institute for Environmental Studies, Onogawa 16-2, Tsukuba, Ibaraki 305-8506, Japan.
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Tsukahara S, Kakeyama M, Toyofuku Y. Sex differences in the level of Bcl-2 family proteins and caspase-3 activation in the sexually dimorphic nuclei of the preoptic area in postnatal rats. ACTA ACUST UNITED AC 2007; 66:1411-9. [PMID: 17013925 DOI: 10.1002/neu.20276] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
In developing rats, sex differences in the number of apoptotic cells are found in the central division of the medial preoptic nucleus (MPNc), which is a significant component of the sexually dimorphic nucleus of the preoptic area, and in the anteroventral periventricular nucleus (AVPV). Specifically, male rats have more apoptotic cells in the developing AVPV, whereas females have more apoptotic cells in the developing MPNc. To determine the mechanisms for the sex differences in apoptosis in these nuclei, we compared the expression of the Bcl-2 family members and active caspase-3 in postnatal female and male rats. Western blot analyses for the Bcl-2 family proteins were performed using preoptic tissues isolated from the brain on postnatal day (PD) 1 (day of birth) or on PD8. In the AVPV-containing tissues of PD1 rats, there were significant sex differences in the level of Bcl-2 (female > male) and Bax (female < male) proteins, but not of Bcl-xL or Bad proteins. In the MPNc-containing tissues of PD8 rats, there were significant sex differences in the protein levels for Bcl-2 (female < male), Bax (female > male), and Bad (female < male), but not for Bcl-xL. Immunohistochemical analyses showed significant sex differences in the number of active caspase-3-immunoreactive cells in the AVPV on PD1 (female < male) and in the MPNc on PD8 (female > male). We further found that active caspase-3-immunoreactive cells of the AVPV and MPNc were immunoreactive for NeuN, a neuronal marker. These results suggest that there are sex differences in the induction of apoptosis via the mitochondrial pathway during development of the AVPV and MPNc.
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Affiliation(s)
- Shinji Tsukahara
- Environmental Health Science Division, National Institute for Environmental Studies, Onogawa16-2, Tsukuba 305-8506, Japan.
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Somboonporn W, Davis SR. Postmenopausal testosterone therapy and breast cancer risk. Maturitas 2004; 49:267-75. [PMID: 15531122 DOI: 10.1016/j.maturitas.2004.06.020] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2004] [Revised: 04/15/2004] [Accepted: 06/17/2004] [Indexed: 11/18/2022]
Abstract
BACKGROUND Testosterone therapy is being increasingly used in the management of postmenopausal women. However, as clinical trials have demonstrated a significantly increased risk of breast cancer with oral combined estrogen-progestin therapy, there is a need to ascertain the risk of including testosterone in such regimens. OBJECTIVE Evaluation of experimental and epidemiological studies pertaining to the role of testosterone in breast cancer. DESIGN Literature review. SETTING The Jean Hailes Foundation, Research Unit. MAIN OUTCOME MEASURES Mammary epithelial proliferation, apoptosis and breast cancer. RESULTS In experimental studies, testosterone action is anti-proliferative and pro-apoptotic, and mediated via the AR, despite the potential for testosterone to be aromatized to estrogen. Animal studies suggest that testosterone may serve as a natural, endogenous protector of the breast and limit mitogenic and cancer promoting effects of estrogen on mammary epithelium. In premenopausal women, elevated testosterone is not associated with greater breast cancer risk. The risk of breast cancer is also not increased in women with polycystic ovary syndrome who have chronic estrogen exposure and androgen excess. However, in postmenopausal women, who are oestrogen deplete and have increased adipose aromatase activity, higher testosterone has been associated with greater breast cancer risk. CONCLUSION Available data indicate the inclusion of testosterone in estrogen-progestin regimens has the potential to ameliorate the stimulating effects of hormones on the breast. However, testosterone therapy alone cannot be recommended for estrogen deplete women because of the potential risk of enhanced aromatisation to estrogen in this setting.
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Affiliation(s)
- Woraluk Somboonporn
- Department of Obstetrics and Gynaecology, Khon Kaen University, Khon Kaen, Thailand
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Abstract
Androgens have important physiological effects in women. Postmenopausal androgen replacement, most commonly as testosterone therapy, is becoming increasingly widespread. This is despite the lack of clear guidelines regarding the diagnosis of androgen insufficiency, optimal therapeutic doses, and long-term safety data. With respect to the breast specifically, there is the potential for exogenous testosterone to exert either androgenic or indirect estrogenic actions, with the latter potentially increasing breast cancer risk. In experimental studies, androgens exhibit growth-inhibitory and apoptotic effects in some, but not all, breast cancer cell lines. Differing effects between cell lines appear to be due primarily to variations in concentrations of specific coregulatory proteins at the receptor level. In rodent breast cancer models, androgen action is antiproliferative and proapoptotic, and is mediated via the androgen receptor, despite the potential for testosterone and dehydroepiandrosterone to be aromatized to estrogen. The results from studies in rhesus monkeys suggest that testosterone may serve as a natural endogenous protector of the breast and limit mitogenic and cancer-promoting effects of estrogen on mammary epithelium. Epidemiological studies have significant methodological limitations and provide inconclusive results. The strongest data for exogenous testosterone therapy comes from primate studies. Based on such simulations, inclusion of testosterone in postmenopausal estrogen-progestin regimens has the potential to ameliorate the stimulating effects of combined estrogen-progestin on the breast. Research addressing this is warranted; however, the number of women that would be required for an adequately powered randomized controlled trial renders such a study unlikely.
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Affiliation(s)
- Woraluk Somboonporn
- Department of Obstetrics and Gynaecology, Monash University, Clayton, Victoria 3168, Australia.
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Leung G, Tsao SW, Wong YC. Sex hormone-induced mammary carcinogenesis in female Noble rats: detection of differentially expressed genes. Breast Cancer Res Treat 2003; 77:49-63. [PMID: 12602904 DOI: 10.1023/a:1021123914339] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Breast cancer is the most common cancer and the second most frequent cause of cancer death in women. Epidemiological data has recognized that an increased cumulative exposure to estrogen is the common tie linking most of the established risk factors for breast cancer. Sex hormone-induced mammary gland carcinogenesis of the Noble rat (using testosterone and 17beta-estradiol) resembles that of the human counterpart in its growth pattern as well as the histopathology of the tumors induced. This model may provide a paradigm for examination of genetic alterations and changes in gene expression between different histological groups and to make inferences about the role of known and putative oncogenes and tumor suppressor genes. We studied the gene expression profile during sex hormone-induced mammary carcinogenesis using a cDNA array technique; the results were further confirmed by RT-PCR, western blotting and immunohistochemical analyses. From the 10 differentially expressed genes identified, we have studied four highly overexpressed genes, two cell cycle/growth control regulators, the cyclins D1 and D2, a growth factor, IGF-2 and a cytokine TNF-alpha. Cyclins D1 and D2 were highly expressed in the nuclei of carcinoma cells but at low levels in the nuclei of the hyperplastic and normal mammary tissue. IGF-2 was found to expressed in the cytoplasm of the carcinoma cells but not in the stromal cells. Western blot showed expression of big IGF-2 consistent with the tumor derived truncated forms of pro-IGF-2. The matured circulating IGF-2 at 7.5 kDa identified in the serum was not expressed in any of the breast tissue samples. TNF-alpha expression was found not only in the macrophages but also in the mammary carcinoma cells. The result of the present study provides some information on the molecular basis of this sex hormone-induced mammary carcinogenesis and the role of these proteins in tumor progression.
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Affiliation(s)
- G Leung
- Department of Anatomy, Faculty of Medicine, University of Hong Kong, New Medical Complex, Pokfulam, Hong Kong, China
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Leung G, Benzie IFF, Cheung A, Tsao SW, Wong YC. No effect of a high-fat diet on promotion of sex hormone-induced prostate and mammary carcinogenesis in the Noble rat model. Br J Nutr 2002; 88:399-409. [PMID: 12323089 DOI: 10.1079/bjn2002673] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Results of international correlation and migrant studies suggest that dietary fat promotes carcinogenesis in hormone-sensitive sites, but this is disputed. In the present study, we used a Noble rat model of sex hormone-induced cancers to examine the effect of a high-fat diet on the incidence and latency of prostate and mammary cancer in male (n 139) and female (n 72) animals respectively. We also measured alpha-tocopherol levels in female breast tissue to determine whether a high intake of polyunsaturated fatty acids depletes antioxidant defence in target tissues, providing a possible potentiating mechanism for carcinogenesis. Results showed a very high incidence of hormone-induced adenocarcinomas of prostate and mammary gland, irrespective of diet. There was no difference in the pattern of carcinogenesis in different prostatic locations, weight of the prostate, or weight gain between male rats on the high-fat diet compared with the control (standard, low-fat) diet. In female rats, the incidence of mammary cancer and the body-weight gain were the same in both dietary groups, and breast alpha-tocopherol was also unaffected by dietary fat intake. Our present results are supportive of recent cohort studies that reported no significant association between intake of fat and the development of human prostate and breast cancer, and do not support a role for dietary fat in promoting sex hormone-induced prostate and mammary carcinogenesis.
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Affiliation(s)
- G Leung
- Department of Anatomy, Faculty of Medicine, University of Hong Kong, Hong Kong
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Leung G, Tsao SW, Wong YC. The effect of flutamide and tamoxifen on sex hormone-induced mammary carcinogenesis and pituitary adenoma. Breast Cancer Res Treat 2002; 72:153-62. [PMID: 12038706 DOI: 10.1023/a:1014864231689] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
We have established a female Noble rat model to explore the mechanisms of hormonal mammary carcinogenesis. Based on the previous finding that the dose of testosterone affects only the latency period of mammary cancer, not the final incidence and that androgen upregulates apoptotic activity in pre-malignant mammary glands, we hypothesised that estrogen is the initiator and androgen the promoter for hormonal mammary carcinogenesis of the rats. In the present study, rats were treated with the sex hormones together with flutamide and tamoxifen for both short term (7 and 13 weeks) and long term (12 months) durations. We showed that tamoxifen could totally inhibit mammary carcinogenesis while flutamide cause a delay and reduction in tumour incidence in the 12 months treatment term. Blocking effect of flutamide and tamoxifen on T + E2 (testosterone and 17beta-estradiol) short-terms treatment was demonstrated by the similar histological changes identified in the mammary glands of the T + E2 and drug treated rats to that of the age matched E2 and T controls, respectively. These findings give further support for the role of estrogen and androgen in mammary carcinogenesis. Autopsy of the tumour bearing rats showed presence of pituitary macroadenoma causing compression and atrophy of the brain stem. Immunohistochemical staining of these adenomas showed a predominance of prolactin-secreting cells. Serum assay also showed a corresponding increase in circulatory prolactin level. Tamoxifen was also effective in blocking the formation of pituitary adenoma in the sex hormone treated rats. Pituitary size and level of prolactin were higher in the T + E2 + flutamide group than the T + E2 group in both short-term and long-term treatments. It suggests that testosterone may have a role in counteracting estradiol stimulation on the pituitary lactotropes although it is synergistic to estrogen in mammary carcinogenesis. Pituitary adenomas were found in all rats that developed mammary adenocarcinoma but not vice versa suggesting that prolactin level elevation alone cannot lead to mammary tumorigenesis. The animal model, in addition to mammary carcinogenesis, may be useful for investigation of anti-estrogen therapy in pituitary adenomas.
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Affiliation(s)
- G Leung
- Department of Anatomy, Faculty of Medicine, University of Hong Kong, China
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Liao DJ, Dickson RB. Roles of androgens in the development, growth, and carcinogenesis of the mammary gland. J Steroid Biochem Mol Biol 2002; 80:175-89. [PMID: 11897502 DOI: 10.1016/s0960-0760(01)00185-6] [Citation(s) in RCA: 117] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Androgens influence the development and growth of the mammary gland in women. Treatment of animals and cultured cells with androgens has either inhibitory or stimulatory effects on the proliferation of mammary epithelia and cancer cells; the mechanisms for these dual functions are still not very clear and are discussed in this review. Epidemiological data suggest that, similar to increased estrogens, elevated androgens in serum may be associated with the development of breast cancer. Experiments in rodents have also shown that simultaneous treatment of androgen and estrogen synergizes for mammary gland carcinogenesis. Similar synergistic effects of both hormones have been observed for carcinogenesis of the uterine myometrium of female animals and for carcinogenesis of the prostate and deferens of males. There are also clinical and experimental indications for a possible association of elevated levels of both androgens and estrogens with the development of ovarian and endometrial cancers. A hypothesis is thus proposed that concomitant elevation in both androgens and estrogens may confer a greater risk for tumorigenesis of the mammary gland, and probably other female reproductive tissues than an elevation of each hormone alone.
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Affiliation(s)
- Dezhong J Liao
- Department of Oncology, Lombardi Cancer Center, Georgetown University Medical Center Research Building, W416, 3970 Reservoir Road NW, Washington, DC 20007, USA.
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