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MARK4 inhibits Hippo signaling to promote proliferation and migration of breast cancer cells.

ABSTRACT: The Hippo pathway is a critical regulator of tissue size, and aberrations in pathway regulation lead to cancer. MST1/2 and LATS1/2 kinases comprise the core of the pathway that, in association with adaptor proteins SAV and MOB, functions in a sequential manner to phosphorylate and inhibit the transcription factors YAP and TAZ. Here we identify mammalian MARK family members as activators of YAP/TAZ. We show that depletion of MARK4 in MDA-MB-231 breast cancer cells results in the loss of nuclear YAP/TAZ and decreases the expression of YAP/TAZ targets. We demonstrate that MARK4 can bind to MST and SAV, leading to their phosphorylation, and that MARK4 expression attenuates the formation of a complex between MST/SAV and LATS, which depends on the kinase activity of MARK4. Abrogation of MARK4 expression using siRNAs and CRISPR/Cas9 gene editing attenuates the proliferation and migration of MDA-MB-231 cells. Our results show that MARK4 acts as a negative regulator of the Hippo kinase cassette to promote YAP/TAZ activity and that loss of MARK4 restrains the tumorigenic properties of breast cancer cells.

SUBMITTER: Heidary Arash E

PROVIDER: S-EPMC5331264 | biostudies-literature | 2017 Mar

REPOSITORIES: biostudies-literature

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MARK4 inhibits Hippo signaling to promote proliferation and migration of breast cancer cells.

Heidary Arash Emad E Shiban Ahmed A Song Siyuan S Attisano Liliana L

EMBO reports 20170209 3

The Hippo pathway is a critical regulator of tissue size, and aberrations in pathway regulation lead to cancer. MST1/2 and LATS1/2 kinases comprise the core of the pathway that, in association with adaptor proteins SAV and MOB, functions in a sequential manner to phosphorylate and inhibit the transcription factors YAP and TAZ. Here we identify mammalian MARK family members as activators of YAP/TAZ. We show that depletion of MARK4 in MDA-MB-231 breast cancer cells results in the loss of nuclear Y ...[more]

PMID: 28183853

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Project description:BACKGROUND:An increasing number of studies have shown that long noncoding RNAs (lncRNAs) play essential roles in tumor initiation and progression. LncRNAs act as tumor promoters or suppressors by targeting specific genes via epigenetic modifications and competing endogenous RNA (ceRNA) mechanisms. In this study, we explored the function and detailed mechanisms of long intergenic nonprotein coding RNA 673 (LINC00673) in breast cancer progression. METHODS:Quantitative real-time PCR (qRT-PCR) was used to examine the expression of LINC00673 in breast cancer tissues and in adjacent normal tissues. Gain-of-function and loss-of function experiments were conducted to investigate the biological functions of LINC00673 in vitro and in vivo. We also explored the potential role of LINC00673 as a therapeutic target using antisense oligonucleotide (ASO) in vivo. RNA sequencing (RNA-seq), dual-luciferase reporter assays, chromatin immunoprecipitation (ChIP) assay, and rescue experiments were performed to uncover the detailed mechanism of LINC00673 in promoting breast cancer progression. RESULTS:In the present study, LINC00673 displayed a trend of remarkably increased expression in breast cancer tissues and was associated with poor prognosis in breast cancer patients. Importantly, LINC00673 depletion inhibited breast cancer cell proliferation by inhibiting the cell cycle and increasing apoptosis. Furthermore, ASO therapy targeting LINC00673 substantially suppressed breast cancer cell proliferation in vivo. Mechanistically, LINC00673 was found to act as a ceRNA by sponging miR-515-5p to regulate MARK4 expression, thus inhibiting the Hippo signaling pathway. Finally, ChIP assay showed that the transcription factor Yin Yang 1 (YY1) could bind to the LINC00673 promoter and increase its transcription in cis. CONCLUSIONS:YY1-activated LINC00673 may exert an oncogenic function by acting as a sponge for miR-515-5p to upregulate the MARK4 and then inhibit Hippo signaling pathway, and may serve as a potential therapeutic target.

Project description:Triple-negative breast cancer (TNBC) is an aggressive clinical subtype of breast cancer that is characterized by the lack of estrogen receptor (ER) and progesterone receptor (PR) expression as well as human epidermal growth factor receptor 2 (HER2) overexpression. The TNBC subtype constitutes approximately 10%-20% of all breast cancers, but has no effective molecular targeted therapies. Previous meta-analysis of gene expression profiles of 587 TNBC cases from 21 studies demonstrated high expression of Wnt signaling pathway-associated genes in basal-like 2 and mesenchymal subtypes of TNBC. In this study, we investigated the potential of Wnt pathway inhibitors in effective treatment of TNBC.Activation of Wnt pathway was assessed in four TNBC cell lines (BT-549, MDA-MB-231, HCC-1143 and HCC-1937), and the ER+ cell line MCF-7 using confocal microscopy and Western blot analysis of pathway components. Effectiveness of five different Wnt pathway inhibitors (iCRT-3, iCRT-5, iCRT-14, IWP-4 and XAV-939) on cell proliferation and apoptosis were tested in vitro. The inhibitory effects of iCRT-3 on canonical Wnt signaling in TNBC was evaluated by quantitative real-time RT-PCR analysis of Axin2 and dual-luciferase reporter assays. The effects of shRNA knockdown of SOX4 in combination with iCRT-3 and/or genistein treatments on cell proliferation, migration and invasion on BT-549 cells were also evaluated.Immunofluorescence staining of ?-catenin in TNBC cell lines showed both nuclear and cytoplasmic localization, indicating activation of Wnt pathway in TNBC cells. iCRT-3 was the most effective compound for inhibiting proliferation and antagonizing Wnt signaling in TNBC cells. In addition, treatment with iCRT-3 resulted in increased apoptosis in vitro. Knockdown of the Wnt pathway transcription factor, SOX4 in triple negative BT-549 cells resulted in decreased cell proliferation and migration, and combination treatment of iCRT-3 with SOX4 knockdown had a synergistic effect on inhibition of cell proliferation and induction of apoptosis.These data suggest that targeting SOX4 and/or the Wnt pathway could have therapeutic benefit for TNBC patients.

Project description:Purpose:Evidence describing TMED3 in the context of breast cancer is scarce, and the effect of TMED3 on Wnt/?-catenin signaling in breast cancer has not been reported. The objective of this study was to determine the potential physiological functions and molecular mechanisms of TMED3 in breast cancer. Materials and Methods:Quantitative real-time PCR and Western blot analysis were used to analyze the expression of TMED3 mRNA and protein in 182 paraffin-embedded primary breast cancer tissues and 60 paired noncancerous tissues and 25 fresh primary breast cancer tissues and surrounding adjacent noncancerous tissues. Associations between TMED3 expression and clinicopathologic factors or overall survival were determined. The effects of overexpression or knockdown of TMED3 on proliferation, migration, invasion, and cell cycle progression in breast cancer cell lines were investigated with the Cell Counting Kit-8, clone formation assay, transwell assay, wound healing assay, and flow cytometry, respectively. Immunofluorescence and Western blot analysis were used to detect the expression of cell cycle, migration-related, and Wnt/?-catenin signaling proteins. Results:The expression of TMED3 mRNA and protein were significantly increased in breast cancer tissues and cell lines compared to normal controls. TMED3 upregulation was significantly correlated with clinicopathologic characteristics and predicted poor prognosis in patients with breast cancer. TMED3 overexpression promoted proliferation, migration, invasion, and cell cycle progression compared to controls in breast cancer cell lines. TMED3 knockdown suppressed proliferation, migration, invasion, and cell cycle progression compared to controls in breast cancer cell lines. TMED3 promoted proliferation and migration of breast cancer cells by a mechanism that involved Wnt/?-catenin signaling. Conclusion:TMED3 behaves as an oncogene that promotes the proliferation and migration of breast cancer cells by a mechanism that involved Wnt/?-catenin signaling. Strategies targeting TMED3 have potential therapeutic implications for patients with breast cancer.

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MARK4 inhibits Hippo signaling to promote proliferation and migration of breast cancer cells.

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MARK4 inhibits Hippo signaling to promote proliferation and migration of breast cancer cells.

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