Uncovering BRCAI-regulated signalling pathways by microarray-based expression profiling

The introduction of microarray technology to the scientific and medical communities has dramatically changed the way in which we now address basic biomedical questions. Expression profiling using microarrays facilitates an experimental approach where alterations in the transcript level of entire transcriptomes can be simultaneously assayed in response to defined stimuli. We have used microarray analysis to identify downstream transcriptional targets of the BRCA1 (Breast Cancer 1) tumour-suppressor gene as a means of defining its function. BRCA1 has been implicated in the predisposition to early onset breast and ovarian cancer and while its exact function remains to be defined, roles in DNA repair, cell-cycle control and transcriptional regulation have been implied. In the current study we have generated cell lines with tetracycline-regulated, inducible expression of BRCA1 as a tool to identify genes, which might represent important effectors of BRCA1 function. Oligonucleotide array-based expression profiling identified a number of genes that were upregulated at various times following inducible expression of BRCA1 including the DNA damage-responsive gene GADD45 (Growth Arrest after DNA Damage). Identified targets were confirmed by Northern blot analysis and their functional significance as BRCA1 targets examined.

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CLL Tumours with a Deletion of 11q Form Two Functional Subgroups Based on the Mutation Status of the Remaining ATM Allele.

Blood ◽

10.1182/blood.v106.11.710.710 ◽

2005 ◽

Vol 106 (11) ◽

pp. 710-710

Author(s):

Belinda Austen ◽

Maria Podinovskaia ◽

Claire Almond ◽

Graham Fews ◽

Anne Gardiner ◽

...

Keyword(s):

Dna Damage ◽

Suppressor Gene ◽

Tumour Suppressor Gene ◽

Fish Analysis ◽

Wild Type ◽

Atm Gene ◽

Atm Protein ◽

11Q Deletion

Abstract Deletions in chromosome 11q are an established prognostic marker in CLL. One copy of the ATM gene is deleted in these tumours, as detected by FISH analysis. However, it remains unclear whether the ATM gene is the main tumour suppressor gene that is accounting for the poor outcome in tumours with 11q deletions. We have recently reported that patients whose tumours have mutations in the ATM gene have an impaired overall and treatment free survival. In our large cohort of 155 patients, tumours with an ATM mutation only partly correlated with tumours with an 11q deletion. We have therefore investigated the relationship between 11q deletions and mutations in the ATM gene. Using the highly sensitive DHPLC method, we have screened the 60 ATM coding exons for mutations in a cohort of 46 tumours, all with a deletion of chromosome 11q. We have found ATM mutations in 19 tumours, indicating a prevalence of 41%. The ATM protein is vital in the cell’s response to DNA damage including that induced by chemotherapy. ATM acts upstream from p53 and defects in ATM function, like p53, lead to impaired DNA damage induced apoptosis. Furthermore, we have previously shown that loss of ATM function is associated with both in vitro and in vivo chemo-resistance. Therefore, we next assessed whether the status of the remaining ATM allele in the 11q deleted tumours affected the response to DNA damage. Firstly we induced DNA damage with irradiation and measured both the phosphorylation of ATM protein targets and the induction of p53 dependent transcription responses in representative samples. We found that 11q deleted tumours with a remaining wild type ATM allele had responses that were similar to those seen in tumours with two wild type ATM alleles. In contrast, 11q deleted tumours with a mutation in the remaining ATM allele had defective DNA damage induced responses. We then analysed the effects of in vitro treatment with Fludarabine. First we demonstrated that fludarabine induces ATM dependent phophosphorylation responses in CLL tumours. Then we analysed its effect in the two 11q deleted CLL subgroups. We showed defective phosphorylation responses to fludarabine in the tumours with a mutation in the second ATM allele, but normal responses in those with a second wild type ATM allele. In summary, we have shown that approximately 40% of CLL tumours with an 11q deletion have a mutation in their remaining ATM allele. Furthermore, we have demonstrated that the 11q deleted tumours appear to form two functional subgroups based on the presence of a mutation in the remaining ATM allele. In contrast to the subgroup with a wild type ATM allele, CLL tumours with a mutant ATM allele have defective in vitro responses to DNA damage with both irradiation and fludarabine. We expect that the functional differences between the two 11q deleted subsets will translate into differences in clinical outcome.

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HUWE 1 is a critical colonic tumour suppressor gene that prevents MYC signalling, DNA damage accumulation and tumour initiation

EMBO Molecular Medicine ◽

10.15252/emmm.201606684 ◽

2016 ◽

Vol 9 (2) ◽

pp. 181-197 ◽

Cited By ~ 37

Author(s):

Kevin B Myant ◽

Patrizia Cammareri ◽

Michael C Hodder ◽

Jimi Wills ◽

Alex Von Kriegsheim ◽

...

Keyword(s):

Dna Damage ◽

Damage Accumulation ◽

Suppressor Gene ◽

Tumour Suppressor Gene ◽

Tumour Suppressor ◽

Colonic Tumour ◽

Tumour Initiation

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DNA damage signalling recruits RREB-1 to the p53 tumour suppressor promoter

Biochemical Journal ◽

10.1042/bj20090342 ◽

2009 ◽

Vol 422 (3) ◽

pp. 543-551 ◽

Cited By ~ 23

Author(s):

Hanshao Liu ◽

Hoi Chin Hew ◽

Zheng-Guang Lu ◽

Tomoko Yamaguchi ◽

Yoshio Miki ◽

...

Keyword(s):

Dna Damage ◽

Target Genes ◽

Core Promoter ◽

Genotoxic Stress ◽

Suppressor Gene ◽

Tumour Suppressor Gene ◽

Tumour Suppressor ◽

Dependent Manner ◽

P53 Expression ◽

Protein Levels

Transcriptional regulation of the p53 tumour suppressor gene plays an important role in the control of the expression of various target genes involved in the DNA damage response. However, the molecular basis of this regulation remains obscure. In the present study we demonstrate that RREB-1 (Ras-responsive-element-binding protein-1) efficiently binds to the p53 promoter via the p53 core promoter element and transactivates p53 expression. Silencing of RREB-1 significantly reduces p53 expression at both the mRNA and the protein levels. Notably, disruption of RREB-1-mediated p53 transcription suppresses the expression of the p53 target genes. We also show that, upon exposure to genotoxic stress, RREB-1 controls apoptosis in a p53-dependent manner. These findings provide evidence that RREB-1 participates in modulating p53 transcription in response to DNA damage.

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PTEN is essential for cell migration but not for fate determination and tumourigenesis in the cerebellum

Development ◽

10.1242/dev.129.14.3513 ◽

2002 ◽

Vol 129 (14) ◽

pp. 3513-3522 ◽

Cited By ~ 2

Author(s):

Silvia Marino ◽

Paul Krimpenfort ◽

Carly Leung ◽

Hetty A. G. M. van der Korput ◽

Jan Trapman ◽

...

Keyword(s):

Central Nervous System ◽

Nervous System ◽

System Development ◽

Cell Cycle Control ◽

Neoplastic Transformation ◽

Suppressor Gene ◽

Tumour Suppressor Gene ◽

Nervous System Development ◽

A Cell ◽

And Migration

PTEN is a tumour suppressor gene involved in cell cycle control, apoptosis and mediation of adhesion and migration signalling. Germline mutations of PTEN in humans are associated with familial tumour syndromes, among them Cowden disease. Glioblastomas, highly malignant glial tumours of the central nervous system frequently show loss of PTEN. Recent reports have outlined some aspects of PTEN function in central nervous system development. Using a conditional gene disruption approach, we inactivated Pten in mice early during embryogenesis locally in a region specific fashion and later during postnatal development in a cell-specific manner, to study the role of PTEN in differentiation, migration and neoplastic transformation. We show that PTEN is required for the realisation of normal cerebellar architecture, for regulation of cell and organ size, and for proper neuronal and glial migration. However, PTEN is not required for cell differentiation and lack of PTEN is not sufficient to induce neoplastic transformation of neuronal or glial cells

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