Skip to main page content
U.S. flag

An official website of the United States government

Dot gov

The . gov means it’s official. Federal government websites often end in . gov or VSports app下载. mil. Before sharing sensitive information, make sure you’re on a federal government site. .

Https

The site is secure. The https:// ensures that you are connecting to the official website and that any information you provide is encrypted and transmitted securely V体育官网. .

. 2013 Nov 15;12(1):138.
doi: 10.1186/1476-4598-12-138.

Ets-1 regulates intracellular glutathione levels: key target for resistant ovarian cancer

Meghan L Verschoor, Gurmit Singh  1
Affiliations

"VSports" Ets-1 regulates intracellular glutathione levels: key target for resistant ovarian cancer

"V体育官网入口" Meghan L Verschoor et al. Mol Cancer. .

"VSports注册入口" Abstract

Background: Ovarian cancer is characterized by high rates of metastasis and therapeutic resistance VSports手机版. Many chemotherapeutic agents rely on the induction of oxidative stress to cause cancer cell death, thus targeting redox regulation is a promising strategy to overcome drug resistance. .

Methods: We have used a tetracycline-inducible Ets-1 overexpression model derived from 2008 ovarian cancer cells in the present study. To examine the role of Ets-1 in glutathione regulation we have measured intracellular reactive oxygen species and glutathione levels, as well as glutathione peroxidase enzyme activity. Glutathione synthesis was limited using transsulfuration or Sx(c)- pathway blocking agents, and glutamate release was measured to confirm Sx(c)- blockade V体育安卓版. Cell viability following drug treatment was assessed via crystal violet assay. Oxidative stress was induced through glucose oxidase treatment, which produces hydrogen peroxide by glucose oxidation. The protein expressions of redox-related factors were measured through western blotting. .

Results: Overexpression of Ets-1 was associated with decreased intracellular ROS, concomitantly with increased intracellular GSH, GPX antioxidant activity, and Sx(c)- transporter activity. Under basal conditions, inhibition of the transsulfuration pathway resulted in decreased GSH levels and GPX activity in all cell lines, whereas inhibition of Sx(c)- by sulfasalazine decreased GPX activity in Ets-1-expressing cells only. However, under oxidative stress the intracellular GSH levels decreased significantly in correlation with increased Ets-1 expression following sulfasalazine treatment V体育ios版. .

Conclusions: In this study we have identified a role for proto-oncogene Ets-1 in the regulation of intracellular glutathione levels, and examined the effects of the anti-inflammatory drug sulfasalazine on glutathione depletion using an ovarian cancer cell model. The findings from this study show that Ets-1 mediates enhanced Sx(c)- activity to increase glutathione levels under oxidative stress, suggesting that Ets-1 could be a promising putative target to enhance conventional therapeutic strategies VSports最新版本. .

PubMed Disclaimer

Figures

Figure 1
Figure 1
Ets-1 decreases intracellular ROS, while increasing intracellular GSH and GPX activity. A) Basal intracellular ROS levels were measured in 2008, 2008-Ets1 (Ets-1), and tetracycline-induced 2008-Ets1 (Ets-1 + Tet) cells using CM2-H2DCFDA. There is a trend for decreased ROS levels in correlation with increased Ets-1 expression (n = 3). B) Total intracellular amounts of GSH were measured using an enzymatic recycling method as described by Rahman et al. (12). Metabolite extracts from 2008, Ets-1 and induced Ets-1 cells contained increased GSH levels concomitantly with increased Ets-1 expression (n = 4). C) Glutathione peroxidase activity also displayed a trend towards increased activity in association with higher levels of Ets-1 expression (n = 4).
Figure 2
Figure 2
Ets-1 increases System xc- expression and activity. A) The protein expression of the catalytic subunit of Sxc-, xCT, and the transsulfuration pathway enzyme CBS were compared in 2008 and induced 2008-Ets1 cells via Western Blot. Though the expression of CBS was not different, xCT protein levels were increased in response to Ets-1 overexpression (n = 3). B) Glutamate release was measured by AMPLEX red® fluorescence in 2008 and 2008-Ets1 cells under basal or SAS-treated conditions. Cells that overexpress Ets-1 release more glutamate into the culture medium, and SAS was an effective inhibitor of glutamate release (n = 3). C) Cell viability was measured via Crystal Violet assay following SAS treatment, which was found to decrease viability in all cell lines (n=3).
Figure 3
Figure 3
The transsulfuration pathway is a major GSH source in normoxic ovarian cancer cells. 2008, 2008-Ets1 and induced 2008-Ets1 ovarian cancer cells were treated with PPG or SAS for 24 hrs, and the redox capacity was examined. A) Quantitative total GSH levels were significantly decreased in response to PPG treatment in all cell lines, while SAS did not significantly affect GSH levels (n = 3). B) Like total GSH levels, enzyme activity of GPX was significantly decreased by PPG-mediated blockade of the transsulfuration pathway. SAS treatment resulted in decreased GPX activity only in Ets-1 overexpression cell lines (n = 3). C) The protein expression of factors involved in redox regulation was measured via Western blot, including Ets-1, HIF-1α, xCT, GPX-1, and GPX-2, with actin as a loading control (n = 3).
Figure 4
Figure 4
Ets-1 recruits Sxc- to maintain glutathione pool under oxidative stress. A) Glucose oxidase was used to induce oxidative stress in cultures, and successfully increased intracellular ROS levels in all cell lines. B) Under oxidative stress, PPG treatment resulted in decreased intracellular GSH levels. The amount of GSH was decreased by SAS in only ovarian cancer cells that express Ets-1 in abundance.
Figure 5
Figure 5
Ets-1 redox regulation involves changes in HIF-1 and GPX-2 protein levels. A) The protein expression of redox balance-related factors was examined by Western blot. B) Both xCT and GPX-1 protein are increased in correlation with Ets-1 overexpression, while HIF-1α and GPX-2 showed a trend to decreased with higher levels of Ets-1. C) In 2008 cells, HIF-1α and GPX-2 were decreased in response to PPG treatment, while GPX-1 was increased with both PPG and SAS. D) In 2008-Ets1 cells, decreased protein expression was observed for HIF-1α and GPX-2, while SAS also decreased GPX-2 protein levels. E) Similarly, tetracycline-induced 2008-Ets1 cells displayed decreased protein expression of HIF-1α and GPX-2 following PPG and SAS treatment.
Figure 6
Figure 6
Proposed mechanism for Ets-1 mediated drug resistance in ovarian cancer. A) In the absence of abundant Ets-1 expression, the transsulfuration pathway is the main cysteine source for glutathione synthesis. Treatment with chemotherapeutic agents induces oxidative stress that causes DNA damage and GSH depletion by increasing intracellular ROS, leading to cell death. B) Under the control of Ets-1 expression, Sxc- activity is increased to bolster cysteine stores thereby increasing intracellular glutathione. High levels of glutathione prevent oxidative stress-inducing therapies from causing an accumulation of ROS. Thus, Ets-1 overexpression may play an important role in the drug resistance often observed in aggressive ovarian cancer.
See this image and copyright information in PMC

References

    1. Coleman RL, Monk BJ, Sood AK, Herzog TJ. Latest research and treatment of advanced-stage epithelial ovarian cancer. Nat Rev Clin Oncol. 2013;10:211–224. doi: 10.1038/nrclinonc.2013.5. - DOI - PMC - PubMed
    1. Chien J, Kuang R, Landen C, Shridhar V. Platinum-sensitive recurrence in ovarian cancer: the role of tumor microenvironment. Front Oncol. 2013;3:251. - "VSports" PMC - PubMed
    1. Zeimet AG, Reimer D, Sopper S, Boesch M, Martowicz A, Roessler J, Wiedemair AM, Rumpold H, Untergasser G, Concin N. et al.Ovarian cancer stem cells. Neoplasma. 2012;59:747–755. doi: 10.4149/neo_2012_094. - DOI - PubMed
    1. Guddati AK. Ovarian cancer stem cells: elusive targets for chemotherapy. Med Oncol. 2012;29:3400–3408. doi: 10.1007/s12032-012-0252-6. - DOI - PubMed
    1. Aguilar-Gallardo C, Rutledge EC, Martinez-Arroyo AM, Hidalgo JJ, Domingo S, Simon C. Overcoming challenges of ovarian cancer stem cells: novel therapeutic approaches. Stem Cell Rev. 2012;8:994–1010. doi: 10.1007/s12015-011-9344-5. - DOI - PubMed

Publication types (V体育2025版)

"V体育官网" MeSH terms

Substances

V体育平台登录 - LinkOut - more resources