Browsing by Subject "Estrogen"

Now showing 1 - 5 of 5

Open Access
Effect of estrogen on apoptotic regulatory mechanisms in mesenchymal stem cell maintenance
(2006) Terzioğlu, Ece
Mesenchymal Stem Cells (MSCs) can both self-renew and differentiate into fat, bone, cartilage, and muscle. They have a high therapeutic value due to their differentiation potential and nonimmunogenic characteristics, however their rareness and duration of their culture are the main handicaps in their application in cell-based therapies. Therefore, our aim was to explore the possible mechanisms that are involved in MSC maintenance and proliferation by using rat MSCs as a model. We studied the effect of estrogen on MSCs due to its role in growth regulation, differentiation, and cellular proliferation. In MSCs isolated from both normal and ovariectomized animals, the number and the CFU activity were increased when cultured with estrogen. To reveal the mechanism of the action of estrogen on MSC maintenance, we investigated the apoptotic pathway since estrogen has been shown to have a detrimental effect on apoptosis in other systems. The number of apoptotic cells decreased when MSCs were cultured in the presence of estrogen. To elucidate the molecular mechanism of estrogen’s effect on MSC apoptosis, we examined the expression of the bcl-2 family of genes. The expression of anti- apoptotic Bcl-2 and Bcl-xL proteins increased in the presence of estrogen, whereas the expression of proapoptotic Bak decreased. Our results clearly show that estrogen increases the number of the functional MSCs by differentially regulating the expression of the bcl-2 family of genes and inhibiting apoptosis. Therefore estrogen treatment of MSCs may offer a potential to increase the number of MSC for treatments.
Open Access
The Effect of estrogen on bone Marrow-Derived rat mesenchymal stem cell maintenance: inhibiting apoptosis through the expression of bcl-x l and bcl-2
(Springer Science+Business Media, 2012) Ayaloglu-Butun, F.; Terzioglu-Kara, E.; Tokcaer-Keskin, Z.; Akcali, K. C.
Mesenchymal Stem Cells (MSCs) have high therapeutic value for regenerative medicine and tissue engineering due to their differentiation potential and non-immunogenic characteristics. They are also considered as an effective in vivo delivery agent because of their ability to migrate to the site of injury. A major roadblock in their use for cell-based therapies is their rareness in vivo. Therefore, it is important to obtain increased number of functional MSCs in vitro in order to have adequate numbers for therapeutic regiments. We aimed to investigate the role of estrogen and its mechanism in obtaining more MSCs. MSCs were isolated from female and ovariectomized rats and cultured in the presence and absence of 10 -7 M estrogen. In the presence of estrogen, not only their CFU-F activity increased but also apoptotic rate decreased as shown by TUNEL staining leading to obtain more MSCs. Also the number of the cells in the colonies increased upon estrogen treatment. To reveal the mechanism of this effect, we focused on Bcl-2 family of proteins. Our immunoblotting experiments combined with knockdown studies suggested a critical role for anti-apoptotic Bcl-x L and Bcl-2. Estrogen treatment up regulated the expression Bcl-x L and Bcl-2. When we knocked down the expression of bcl-x L and bcl-2, MSCs lacking these genes showed an increase in the apoptotic rate in contrast to normal MSCs following estrogen treatment. Therefore, estrogen treatment will be of great advantage for cell-based therapies in order to get more functional MSCs and may provide opportunities to develop new strategies for debilitating diseases. © 2011 Springer Science+Business Media, LLC.
Open Access
qPCR validation of in vivo diagnostic importance and regulation by estrogen for CHRNA5 isoform expression in breast cancer
(2014) Özdemir, Emine Sıla
Breast cancer has multiple molecular subtypes; normal-like, basal-like, luminal A, luminal B and HER2 positive depending on receptor status of tumor cells. Cancer therapy is tailored according to the type of cancer; hence finding new diagnostic markers is important to decide on the best treatment approach. Cholinergic nicotinic receptor alpha 5 (CHRNA5) is one of the subunits of nicotinic acetylcholine receptors with significant roles in addiction and cancer. In the present study, CHRNA5 has been validated as an estrogen and/or Estrogen receptor (ER) modulated nicotinic acetylcholine receptor by qPCR in in vitro and in vivo in breast cancer samples. CHRNA5 isoform expression was measured using in vitro cell culture studies in which ER- and ER+ cell lines treated with different doses of estradiol (E2); MCF7 cell line was exposed to long-term E2 depletion, in another experiment it was treated with tamoxifen (4-OHT), an ER antagonist, and with or without E2. We found that all CHRNA5 isoforms exhibited increased expression in response to E2 dose-dependently in the ER+ MCF7 cell line while in the ER- MDAMB-231 cell line CHRNA5 isoform expression response was variable in direction and magnitude. CHRNA5 isoform expression in general steadily decreased in ER+ cell line MCF7 after 4-OHT treatment. After six months of E2 depletion, ER+ MCF7 cell line had increased CHRNA5_v3 isoform and ESR1 (ER gene) mRNA expression. In vivo, a human breast cancer cDNA panel was scanned with specially designed primers with qPCR using a custom-written GUI in MATLAB. It was found that CHRNA5, showing a statistically significant difference between normal and tumor cDNA, was a good candidate gene in diagnosis of breast cancer. CHRNA_v3 was able to distinguish between ER+ vs ER- breast tumor samples. We also addressed whether CHRNA5 isoforms exhibited differences in distinguishing tumor stage, and HER2 status. Our findings showed that expression of CHRNA5 isoforms were correlated with each other and regulated by E2 in breast cancer depending on ER receptor status.
Open Access
Regulation of mineralocorticoid receptor and its downstream targets by estrogen and aldosterone in breast cancer
(2016-11) Çoban, Bircan
Many women suffer from breast cancer worldwide thus accurate diagnosis of this disease has become an important issue for treatment options and improved clinical outcomes. Members of steroid hormone receptors, are a subfamily of nuclear receptors can serve as biomarkers in molecular classification of breast cancer. One of these, Mineralocorticoid Receptor (MR) takes part in many physiological processes in epithelial tissues including mammary epithelia, yet it is not well studied in the context of breast cancer. In this thesis, we investigated expression patterns of MR together with Glucocorticoid Receptor (GR) across multiple breast cancer cell lines at the protein level. Our study revealed that expressions of MR and GR were modulated in breast cancer as a subtype specific manner. We then enquired regulation of MR and its downstream targets, SGK1, NEDD4-2 and subunits of ENaC i.e., α, β and γ, by estrogen (E2) and aldosterone (ALDO) treatment in breast cancer via qPCR and Western Blotting. We found differential responses in expression of MR and its downstream targets to E2 and ALDO suggesting ER status was an important mediator of MR action. We also overexpressed MR in MCF7 cells and then showed that MR, NEDD4-2, β and γENaC mRNA levels increased in response to ALDO only when MR was overexpressed.
Open Access
Studies on estradiol dependent transcriptional regulation of human Sodium Iodide Symporter gene in mammary glands
(2002) Gülbağcı, Neriman Tuba
Sodium Iodide Symporter (NIS) is a transmembrane protein, which is expressed in thyroid, mammary gland (mg), stomach, and salivary gland. NIS’s transcriptional regulation in terms of cis-and trans-acting elements in thyroid gland is widely studied. However, despite identification of NIS and studies on its hormonal regulation in mammary gland, cis-and trans-acting elements controlling the mgNIS gene in this tissue are not identified yet. From in vivo experiments, it was learned that estrogen has an up regulatory effect on mgNIS transcriptional regulation. In this study, it was shown that in vitro, estrogen (even in pharmacological concentrations) was not able to induce mgNIS in estrogen receptor positive (ER(+)) MCF-7 breast carcinoma cells, and it had no additive effect on retinoic acid (RA) in NIS up regulation when it was administered in physiological concentrations. In ER (-) MDA-MB-231 breast cancarcinoma cells, ERα might be insufficient to induce mgNIS transcription inspite of the fact that ERα was able to transactivate ERE elements. Interestingly, our study indicates that tamoxifen antagonist of ER, together with estrogen induces mgNIS transcription in MCF-7 cell lines in the absence of RA. This study clearly shows the presence of a yet unidentified link between mgNIS regulation and estrogen responsive mechanisms. Bearing in mind that tamoxifen is a powerful substance in treatment of ER(+) breast cancers, and that radioactive iodide is used in thyroid cancer diagnosis and treatment. This weak induction of mgNIS expression in response to tamoxifen may also have interesting novel applications in fight against breast cancer.