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Proteasome inhibition blocks estrogen-dependent gene transcription by decreasing histone H2B monoubiquitination in human breast cancer cells

ABSTRACT: The estrogen receptor-alpha (ERα) determines breast cancer cell phenotype and is a prognostic indicator. A better understanding of the mechanisms controlling ERα function may uncover improved strategies for the treatment of breast cancer. Proteasome inhibition was previously reported to regulate estrogen-induced transcription but the mechanisms by which it influences ERα function remain controversial. In this study we investigated the transcriptome-wide effects of the proteasome inhibitor Velcade on estrogen-regulated transcription in MCF7 human breast cancer cells and demonstrate a specific global decrease in estrogen-induced transcription. This set contains 12 microarray samples. 3 controls, 3 estrogen stimulated, 3 Bortezomib stimulated, 3 Bortezomib + estrogen stimulated

ORGANISM(S): Homo sapiens

SUBMITTER: Prenzel T

PROVIDER: S-ECPF-GEOD-30931 | biostudies-other | 2011 Sep

REPOSITORIES: biostudies-other

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Project description:AimTo investigate H2B monoubiquitination (uH2B) and H3K4 di- and tri-methylation (H3K4-2me, H3K4-3me) levels and their clinical significance in gastric cancer (GC).MethodsImmunohistochemistry (IGC) was used to detect the differential levels of uH2B, H3K4-2me and H3K4-3me modifications in GC specimens from chemo/radiotherapy-naïve patients who underwent potentially curative surgical resection (n = 159) and in a random sampling of non-tumor gastric epithelium specimens (normal controls, n = 20). The immunohistochemistry (IHC)-detected modifications were classified as negative, low-level, or high-level using a dual-rated (staining intensity and percentage of positively-stained cells) semi-quantitative method. The relationships between uH2B modification levels and clinicopathological parameters of GC were assessed by a Wilcoxon rank sum test (pairwise comparisons) and the Kruskal-Wallis H test (multiple comparisons). The correlation between uH2B modification and survival was estimated by Kaplan-Meier analysis, and the role of uH2B as an independent prognostic factor for survival was assessed by multivariate Cox regression analysis.ResultsThe presence and level of H3K4-2me and H3K4-3me IHC staining was similar between the normal controls and GC specimens. In contrast, the level of uH2B was significantly lower in the malignant gastric tissues (vs normal control tissues) and decreased along with increases in dedifferentiation (well differentiated > moderately differentiated > poorly differentiated). The level of uH2B correlated with tumor differentiation (P < 0.001), Lauren's diffuse- and intestinal-type classification (P < 0.001), lymph node metastasis (P = 0.049) and tumor-node-metastasis stage (P = 0.005). Patients with uH2B+ staining had higher 5-year survival rates than patients with uH2B-staining (52.692 ± 2.452 vs 23.739 ± 5.207, P < 0.001). The uH2B level was an independent prognostic factor for cancer-specific survival (95%CI: 0.237-0.677, P = 0.001).ConclusionuH2B displays differential IHC staining patterns corresponding to progressive stages of GC. uH2B may contribute to tumorigenesis and could be a potential therapeutic target.

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Proteasome inhibition blocks estrogen-dependent gene transcription by decreasing histone H2B monoubiquitination in human breast cancer cells

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