Glucocorticoid-dependent expression of IAP participates in the protection against TNF-mediated cytotoxicity in MCF7 cells

Abstract

Background Glucocorticoid receptor (GR) activation has been associated with breast cancer cell survival in vitro. Glucocorticoid (GC)-dependent protection against tumor necrosis factor (TNF)-induced cell death has been well characterized in MCF7 luminal A breast cancer cells. The GR activates a variety of protective mechanisms, such as inhibitors of apoptosis proteins (IAPs). However, the relative contribution of the GR-dependent expression of IAPs in the protection of cell death has not, to our knowledge, been evaluated. Methods MCF7 cells were used for all experiments. GR was activated with cortisol (CORT) or dexamethasone (DEX) and inhibited with mifepristone (RU486). Cell viability was determined in real-time with the xCELLigence™ RTCA System and at specific endpoints using crystal violet stain. The mRNA levels of the eight members of the IAP family were measured by qRT-PCR. The protein levels of GR, PR, ERα, HER2, PARP1, c-IAP1 and XIAP were evaluated by Western blot analysis. The knockdown of c-IAP1 and XIAP was accomplished via transient transfection with specific siRNAs. GR activation was verified by a gene reporter assay. Via the cBioportal interphase we queried the mRNA levels of GR and IAPs in breast cancer tumors. Results RU486 significantly inhibited the anti-cytotoxic effect of both GCs. PARP1 processing was diminished in the presence of both GCs. The combined treatments of GCs + TNF increased the relative mRNA levels of Survivin>c-IAP1 > NAIP>Apollon>XIAP>Ts-IAP > ML-IAP > c-IAP2. Additionally, GR mRNA content increased with the combined treatments of GCs + TNF. Sustained levels of the proteins c-IAP1 and XIAP were observed after 48 h of the combined treatments with GCs + TNF. With c-IAP1 and XIAP gene silencing, the GC-mediated protection was diminished. In the breast tumor samples, the GR mRNA was coexpressed with Apollon and XIAP with a Pearson coefficient greater than 0.3. Conclusions The effect of GCs against TNF-mediated cytotoxicity involves increased mRNA expression and sustained protein levels of c-IAP1 and XIAP. The antagonist effects of RU486 and the qRT-PCR results also suggest the role of the GR in this process. This finding may have clinical implications because the GR and IAPs are expressed in breast tumor samples. Electronic supplementary material The online version of this article (10.1186/s12885-019-5563-y) contains supplementary material, which is available to authorized users.

Sera from women with different metabolic and menopause states differentially regulate cell viability and Akt activation in a breast cancer in-vitro model

“…On the other hand, among the antitumor mechanisms of Metformin are the inhibition of Akt and NF-κB signaling [ 54 , 78 – 84 ] . While in women whose sera did not induce changes in viability and Akt phosphorylation after treatment with Metformin, we observed a reduction in IKBα degradation and an increase in p65 phosphorylation, independently of phosphorylation of p38, which could indicate that treatment with Metformin in patients with HOMA<3 has an anti-apoptotic effect, although we do not rule out that the observed NF-κB activation could have an anti-tumor effect as has been reported in multiple studies [ 85 – 88 ] . In addition, an increase in p38 phosphorylation was observed in women with and without insulin resistance after treatment with Metformin, which corroborates what was previously reported on an antitumor effect of Metformin through p38 activation [ 89 – 91 ] .…”

Control of Glucocorticoid Receptor Levels by PTEN Establishes a Failsafe Mechanism for Tumor Suppression

“…This was confirmed in T47D cells with targeted PTEN knockdown (sh1 and sh2) and treated with dexa (Figure S3E). Dexa treatment induced a general decrease in GR levels consistent with activation of a negative feedback loop (Gjerstad et al, 2018;Mitre-Aguilar et al, 2015).…”

High lymphocyte‑to‑monocyte ratio is associated with low α‑fetoprotein expression in patients with hepatitis B virus‑associated hepatocellular carcinoma

“…The samples of the AFP-negative and AFP-positive group were incubated with RU486 for 24 h, an inhibitor of dexamethasone ( 41 ). The expression levels of IL-10 were gradually decreased in aforementioned two groups with increasing concentrations of RU486, but the expression of IL-10 was not markedly decreased at 7 µmol ( Fig.…”

“…Multiple mechanisms may be associated with HCC invasion and metastasis, including recombinant human AFP (rhAFP)-induced expression of matrix metallopeptidase 9; C-C chemokine receptor type 5 and AFP mRNA levels; and absent in melanoma 2 protein levels ( 43 , 50 , 51 ). The measurement of the levels of these markers in various neoplasms, limits their wider application for tracking the disease status during the clinical course of treatment ( 41 , 49 ). In contrast to these markers, LMR is a readily measured biomarker that can be used to predict the HCC status ( 49 , 50 , 52 ).…”