MAD2 downregulation in hypoxia is independent of promoter hypermethylation

Prencipe, Maria; McGoldrick, Aloysius; Perry, Antoinette S.; O’Grady, Anthony; Phelan, Sine; McGrogan, Barbara; Fitzpatrick, Patricia; Watson, Jenny; Furlong, Fiona; Brennan, Donal J.; Lawler, Mark; Kay, Elaine W.; McCann, Amanda

doi:10.4161/cc.9.14.12362

Cited by 14 publications

(13 citation statements)

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“…Although reduced MAD2 expression has been reported in human cancer 16, 17, the mechanisms underlying MAD2 down‐regulation remain elusive. Importantly, mutations in the MAD2 gene are reportedly rare in human cancer 18, 19 and we have previously shown that down‐regulation of MAD2 in cancer is not associated with promoter hypermethylation 20.…”

Section: Introductionmentioning

confidence: 85%

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Low MAD2 expression levels associate with reduced progression‐free survival in patients with high‐grade serous epithelial ovarian cancer

Furlong

Fitzpatrick

O’Toole

et al. 2012

The Journal of Pathology

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Epithelial ovarian cancer (EOC) has an innate susceptibility to become chemoresistant. Up to 30% of patients do not respond to conventional chemotherapy [paclitaxel (Taxol®) in combination with carboplatin] and, of those who have an initial response, many patients relapse. Therefore, an understanding of the molecular mechanisms that regulate cellular chemotherapeutic responses in EOC cells has the potential to impact significantly on patient outcome. The mitotic arrest deficiency protein 2 (MAD2), is a centrally important mediator of the cellular response to paclitaxel. MAD2 immunohistochemical analysis was performed on 82 high-grade serous EOC samples. A multivariate Cox regression analysis of nuclear MAD2 IHC intensity adjusting for stage, tumour grade and optimum surgical debulking revealed that low MAD2 IHC staining intensity was significantly associated with reduced progression-free survival (PFS) (p = 0.0003), with a hazard ratio of 4.689. The in vitro analyses of five ovarian cancer cell lines demonstrated that cells with low MAD2 expression were less sensitive to paclitaxel. Furthermore, paclitaxel-induced activation of the spindle assembly checkpoint (SAC) and apoptotic cell death was abrogated in cells transfected with MAD2 siRNA. In silico analysis identified a miR-433 binding domain in the MAD2 3′ UTR, which was verified in a series of experiments. Firstly, MAD2 protein expression levels were down-regulated in pre-miR-433 transfected A2780 cells. Secondly, pre-miR-433 suppressed the activity of a reporter construct containing the 3′-UTR of MAD2. Thirdly, blocking miR-433 binding to the MAD2 3′ UTR protected MAD2 from miR-433 induced protein down-regulation. Importantly, reduced MAD2 protein expression in pre-miR-433-transfected A2780 cells rendered these cells less sensitive to paclitaxel. In conclusion, loss of MAD2 protein expression results in increased resistance to paclitaxel in EOC cells. Measuring MAD2 IHC staining intensity may predict paclitaxel responses in women presenting with high-grade serous EOC. Copyright © 2012 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.

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Section: Introductionmentioning

confidence: 85%

“…Five µm sections were immunostained with the MAD2 monoclonal antibody (BD Transduction Laboratories) at a dilution of 1:100 on an automated platform (Bond™ system, Leica MicroSystems™, Newcastle, UK), as previously described 20.…”

Section: Methodsmentioning

confidence: 99%

Low MAD2 expression levels associate with reduced progression‐free survival in patients with high‐grade serous epithelial ovarian cancer

Furlong

Fitzpatrick

O’Toole

et al. 2012

The Journal of Pathology

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“…Complicated modes of gene regulation such as this have been observed previously. For example, MAD2 is down-regulated in the absence of promoter methylation, 54 and RIZ1 regulation requires both promoter methylation and histone acetylation. 55 Despite methylation-specific PCR being a tried-and-true sensitive method for the detection of promoter methylation, 56 it is not quantitative.…”

Section: Discussionmentioning

confidence: 99%

MicroRNA‐137 promoter methylation is associated with poorer overall survival in patients with squamous cell carcinoma of the head and neck

Langevin

Stone

Bunker

et al. 2010

Cancer

101

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BACKGROUND:The overall 5-year survival rate of approximately 60% for head and neck cancer patients has remained essentially unchanged over the past 30 years. plays an essential role in cell-cycle control at the G1/S-phase checkpoint. However, the aberrant miR-137 promoter methylation observed in squamous cell carcinoma of the head and neck (SCCHN) suggests a tumor-specific molecular defect that may contribute to disease progression. METHODS: The goal of this study was to assess, in formalin-fixed, paraffin-embedded tumor tissue, the association between miR-137 promoter methylation and survival (both overall and disease free) and with prognostic factors including stage, tumor size, lymph node positivity, tumor grade, and surgical tumor margin positivity. RESULTS: The promoter methylation status of miR-137 was ascertained by methylation-specific polymerase chain reaction and detected in 11 of 67 SCCHN patients (16.4%), with no significant differences according to site (oral cavity, pharynx, larynx). Methylation of the miR-137 promoter was significantly associated with overall survival (hazard ratio, 3.68; 95% confidence interval, 1.01-13.38) but not with disease-free survival or any of the prognostic factors evaluated. CONCLUSIONS: The results of this study indicate that miR-137 is methylated in tumor tissue from pharyngeal and laryngeal squamous cancers, in addition to oral squamous cell carcinoma, and that miR-137 promoter methylation has potential utility as a prognostic marker for SCCHN.

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“…However, other mechanisms are also possible. That mitotic factors affect senescence was experimentally proven long ago, 36 but only recently have specific mitotic proteins been implicated in cellular senescence, such as Mad2 37 or CENP-A 38 , which supports a role for mitotic defects caused by ARH depletion as the underlying molecular mechanism for the premature senescent phenotype.…”

Section: Sun Et Al Premature Senescence In Arh Cells 2275mentioning

confidence: 99%

Premature Senescence in Cells From Patients With Autosomal Recessive Hypercholesterolemia (ARH)

Sun

Patel

Acosta

et al. 2011

ATVB

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Objective-The defective gene causing autosomal recessive hypercholesterolemia (ARH) encodes ARH, a clathrinassociated adaptor protein required for low-density-lipoprotein receptor endocytosis in most cells but not in skin fibroblasts. The aim here was to elucidate why ARH fibroblasts grow slowly and undergo premature senescence. Methods and Results-Knockdown of ARH by RNA interference in IMR90 cells produces the same phenotype, indicated by increased p16 expression, ␥-H2AX-positive foci, and enlarged flattened morphology. We showed that ARH contributes to several aspects of mitosis: it localizes to mitotic microtubules, with lamin B1 on the nuclear envelope and spindle matrix, and with clathrin heavy chain on mitotic spindles. Second, ARH is phosphorylated in G 2 /M phase by a roscovitine-sensitive kinase, probably cdc2. Third, cells lacking ARH show disfigured nuclei and defective mitotic spindles. Defects are most marked in ARH W22X cells, where translation starts at Met46, so the protein lacks a phosphorylation site at Ser14, identified by mass spectrometry of wild-type ARH. Conclusion-The ARH protein is involved in cell cycle progression, possibly by affecting nuclear membrane formation through interaction with lamin B1 or other mitotic proteins, and its absence affects cell proliferation and induces premature senescence, which may play a role in the development of atherosclerosis in ARH. Key Words: gene mutations Ⅲ lipoproteins Ⅲ receptors Ⅲ cell division Ⅲ mitosis T he autosomal recessive hypercholesterolemia protein (ARH) is a 32-kDa endocytic adaptor protein involved in low-density-lipoprotein receptor (LDLR) endocytosis. The N terminus of ARH contains a highly conserved sequence of Ϸ40 amino acids with unidentified function, followed by a phosphotyrosine-binding domain of Ϸ130 residues. The C terminus is less conserved, but it contains a clathrin box sequence (LLDLE) and a binding motif for the ␤2 subunit of adaptor protein 2 and a PDZ binding motif with the potential to bind to many signaling proteins (reviewed by Soutar et al 1 ).The uptake of plasma low-density lipoprotein (LDL) by eukaryotic cells occurs via clathrin-dependent LDLRmediated endocytosis. Structure-function studies have shown that ARH regulates endocytosis of LDLR through binding of its phosphotyrosine-binding domain to the NPXY motif in the cytoplasmic tail of the LDLR and other members of its family and binding of its C-terminal motifs to clathrin heavy chain (CHC) and adaptor protein 2. This role is well established from studies in homozygous ARH patients, whose lymphoblasts in culture fail to internalize LDLR and who exhibit severe hypercholesterolemia and premature atherosclerosis because LDL uptake is defective in the liver. 2,3 ARH knockout mice also show impaired endocytosis of LDLR and hypercholesterolemia. 4 Surprisingly, cultured skin fibroblasts from ARH patients exhibit normal internalization of LDLR, 1 possibly because Dab2 can compensate for the absence of ARH in these cells. 5,6 Although it is clear that ARH functions a...

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MAD2 downregulation in hypoxia is independent of promoter hypermethylation

Cited by 14 publications

References 42 publications

Low MAD2 expression levels associate with reduced progression‐free survival in patients with high‐grade serous epithelial ovarian cancer

Low MAD2 expression levels associate with reduced progression‐free survival in patients with high‐grade serous epithelial ovarian cancer

MicroRNA‐137 promoter methylation is associated with poorer overall survival in patients with squamous cell carcinoma of the head and neck

Premature Senescence in Cells From Patients With Autosomal Recessive Hypercholesterolemia (ARH)

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