Dataset Information

RNF168 facilitates oestrogen receptor ? transcription and drives breast cancer proliferation.

ABSTRACT: Oestrogen receptor ? (ER?) is overexpressed in two-thirds of all breast cancers and involves in development and breast cancer progression. Although ER?-positive breast cancer could be effective treated by endocrine therapy, the endocrine resistance is still an urgent clinical problem. Thus, further understanding of the underlying mechanisms ER? signalling is critical in dealing with endocrine resistance in breast cancer patients. MCF-7 and T47D breast cancer cell lines are used to carry out the molecular biological experiments. Western blot is used to assess the relative protein level of ER?, RNF168 and actin. Real-time PCR is used the measure the relative ER?-related gene mRNA level. Luciferase assay is used to measure the relative ER? signalling activity. Chromatin immunoprecipitation is used to measure the RNF168 binding affinity to ER? promoter regions. WST assay and flow cytometry are used to measure the cell proliferation capacity. We use Student's t test and one-way ANOVA test for statistical data analysis. Here, we report an important role in ER?-positive breast cancer cells for RNF168 protein in supporting cell proliferation by driving the transcription of ER?. RNF168 is highly expressed in breast cancer samples, compared with normal breast tissue. In patients with breast cancer, RNF168 expression level is correlated with poor endocrine treatment outcome. Depletion of RNF168 causes decreased cell proliferation in MCF-7 and T47D cells. Besides, depletion RNF168 reduced mRNA level of ER? and its target genes, such as PS2 and GREB1. Chromatin immunoprecipitation revealed that ER? transcription is associated with RNF168 recruitment to ER? promoter region, suggesting that transcriptional regulation is one mechanism by which RNF168 regulates ER? mRNA level and ER? signalling in breast cancer cells. RNF168 is required for ER?-positive breast cancer cell proliferation and facilitate ER? signalling activity possibly through promoting transcription of ER?.

SUBMITTER: Liu Z

PROVIDER: S-EPMC6111850 | biostudies-literature | 2018 Sep

REPOSITORIES: biostudies-literature

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RNF168 facilitates oestrogen receptor ɑ transcription and drives breast cancer proliferation.

Liu Zhenhua Z Zhang Jinghang J Xu Juntao J Yang Huijie H Li Xin X Hou Yingxiang Y Zhao Yan Y Xue Min M Wang Beibei B Yu Na N Yu Sifan S Niu Gang G Wu Gaosong G Li Xiumin X Wang Hui H Zhu Jian J Zhuang Ting T

Journal of cellular and molecular medicine 20180705 9

Oestrogen receptor ɑ (ERɑ) is overexpressed in two-thirds of all breast cancers and involves in development and breast cancer progression. Although ERɑ-positive breast cancer could be effective treated by endocrine therapy, the endocrine resistance is still an urgent clinical problem. Thus, further understanding of the underlying mechanisms ERɑ signalling is critical in dealing with endocrine resistance in breast cancer patients. MCF-7 and T47D breast cancer cell lines are used to carry out the ...[more]

PMID: 29974997

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Project description:IntroductionOestrogens can mediate some of their cell survival properties through a nongenomic mechanism that involves the mitogen-activated protein kinase (MAPK) pathway. The mechanism of this rapid signalling and its dependence on a membrane bound oestrogen receptor (ER), however, remains controversial. The role of G-protein-coupled receptor and epidermal growth factor (EGF) receptor in an ER-independent signalling pathway modulated by oestrogen was investigated.MethodsER-positive and ER-negative breast cancer cell lines (MCF-7 and SKBR3) and primary breast cancer cell cultures were used in this study. Cell proliferation was assessed using standard MTT assays. Protein and cAMP levels were detected by Western blotting and ELISA, respectively. Antigen localization was performed by immunocytochemistry, immunohistochemistry and immunofluorescence. Protein knockdown was achieved using small interfering RNA technologies.ResultsEGF and oestrogen, alone and in combination, induced cell proliferation and phosphorylation of MAPK proteins Raf and ERK (extracellular signal regulated kinase)1/2 in both ER-negative SKBR3 and ER-positive MCF-7 human breast cancer cell lines. Increased Raf phosphorylation was also observed in primary human breast cultures derived from ER-positive and ER-negative breast tumours. Oestrogen induced an increase in intracellular cAMP in ER-negative SKBR3 human breast cancer cells. Oestrogen-mediated cell growth and phosphorylation of MAPK was modified by the EGF receptor antagonist AG1478, the G-protein antagonist pertussis toxin, and the angiotensin II receptor antagonist saralasin. Knockdown of angiotensin II type 1 receptor (AT1) protein expression with small interfering RNA attenuated oestrogen-induced Raf phosphorylation in ER-negative cells. AT1 receptor was found to be expressed in the cell membrane of breast tumour epithelial cells.ConclusionThese findings provide evidence that, in breast cancer cells, oestrogen can signal through AT1 to activate early cell survival mechanisms in an ER-independent manner.

Project description:BackgroundChemotherapy efficacy in early-stage hormone receptor-positive (HR+) breast cancer (BC) according to menopausal status needs a biological explanation.MethodsWe compared early-stage HR+ BC biological features before and after (neo)adjuvant chemotherapy or endocrine therapy (ET), and assessed oestrogen receptor (ER) pathway activity in both pre- and post-menopausal patients. The nCounter platform was used to detect gene expression levels.FindingsIn 106 post-menopausal patients with HR+/HER2-negative BC randomized to neoadjuvant chemotherapy or ET (letrozole+ribociclib), a total of 19 oestrogen-regulated genes, including progesterone receptor (PGR), were found downregulated in the ET-based arm-only. We confirmed this finding in an independent dataset of 20 letrozole-treated post-menopausal patients and found, conversely, an up-regulation of the same signature in HR+/HER2-negative MCF7 cell line treated with estradiol. PGR was found down-regulated by 2 weeks of ET+anti-HER2 therapy in pre-/post-menopausal patients with HR+/HER2-positive (HER2+) BC, while anti-HER2 therapy alone increased PGR expression in HR-negative/HER2+ BC. In 88 pre- and post-menopausal patients with newly diagnosed HR+/HER2-negative BC treated with chemotherapy, the 19 oestrogen-regulated genes were found significantly downregulated only in pre-menopausal patients. In progesterone receptor (PR)+/HER2-negative BC treated with neoadjuvant chemotherapy (n=40), tumours became PR-negative in 69.2% of pre-menopausal patients and 14.8% of post-menopausal patients (p=0.001). Finally, a mean decrease in PGR levels was only observed in pre-menopausal patients undergoing anti-HER2-based multi-agent chemotherapy.InterpretationChemotherapy reduces the expression of ER-regulated genes in pre-menopausal women suffering from hormone-dependent BC by supressing ovarian function. Further studies should test the value of chemotherapy in this patient population when ovarian function is suppressed by other methods.FundingInstituto de Salud Carlos III, Breast Cancer Now, the Breast Cancer Research Foundation, the American Association for Cancer Research, Fundació La Marató TV3, the European Union's Horizon 2020 Research and Innovation Programme, Pas a Pas, Save the Mama, Fundación Científica Asociación Española Contra el Cáncer, PhD4MDgrant of "Departament de Salut", exp SLT008/18/00122, Fundación SEOM and ESMO. Any views, opinions, findings, conclusions, or recommendations expressed in this material are those solely of the author(s).

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Dataset Information

RNF168 facilitates oestrogen receptor ? transcription and drives breast cancer proliferation.

Publications

RNF168 facilitates oestrogen receptor ɑ transcription and drives breast cancer proliferation.

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