The global histone modification pattern correlates with overall survival in metachronous liver metastasis of colorectal cancer
Department of Gastro-intestinal Surgery, Kanagawa Cancer Center, 1-1-2 Nakao, Asahi-ku, Yokohama 241-0815, Japan. Oncology Reports
(Impact Factor: 2.3).
11/2011; 27(3):637-42. DOI: 10.3892/or.2011.1547
Post-translational histone modifications are known to be altered in cancer tissues, and differences in the histone modification levels have recently been used to predict the clinical outcome in patients with certain types of cancer. In this study, we evaluated the immunohistochemical staining patterns of histone H3 dimethylation and acetylation in metachronous liver metastasis of colorectal carcinomas and examined its correlation with patient prognosis. Double 2 mm core tissue microarrays were made from 54 paraffin-embedded samples of liver metastasis from colorectal adenocarcinoma, and were examined by an immunohistochemical analysis of histone H3 lysine 4 (H3K4) dimethylation, histone, H3 lysine 9 (H3K9) dimethylation and histone H3 lysine 9 (H3K9) acetylation. Positive tumor cell staining for each histone modification was used to classify patients into low- and high-staining groups, which were then examined for correlations with the clinicopathological parameters and clinical outcome. Dimethylation of H3K4 correlated with the tumor histological type (P=0.043), and acetylation of H3K9 correlated with the tumor histological type (P=0.016). In addition, lower levels of H3K4 dimethylation correlated with a poor survival rate (P=0.035). The multivariate survival analysis showed that the H3K4 dimethylation status is an independent prognostic factor for colorectal cancer patients (P=0.011). We suggest that the pattern of histone modification as detected by immunohistochemistry may be an independent prognostic factor for metachronous liver metastasis of colorectal carcinomas.
Available from: Agnieszka Paziewska
- "Global hypoacetylation of H4K12 and H3K18 has been observed in undifferentiated colorectal adenocarcinomas, whereas their acetylation was increased in well-differentiated tumours . Contrary to these findings, the H3K9 hypoacetylation status was positively correlated with tumour histological type and low H3K9Ac was observed in well-differentiated tumours . To the best of our knowledge, aberrant H3K27Ac levels in CRC have not been reported to date. "
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Histone post-translational modifications (PTMs) play an important role in the regulation of the expression of genes, including those involved in cancer development and progression. However, our knowledge of PTM patterns in human tumours is limited.
MS-based analyses were used to quantify global alterations of histone PTMs in colorectal cancer (CRC) samples. Histones isolated from 12 CRCs and their corresponding normal mucosa by acidic extraction were separated by SDS-PAGE and analysed by liquid chromatography-mass spectrometry.
Among 96 modified peptides, 41 distinct PTM sites were identified, of which 7, 13, 11, and 10 were located within the H2A, H2B, H3, and H4 sequences, respectively, and distributed among the amino-terminal tails and the globular domain of the four histones. Modification intensities were quantified for 33 sites, of which 4 showed significant (p-value ≤ 0.05) differences between CRC tissues and healthy mucosa samples. We identified histone H3 lysine 27 acetylation (H3K27Ac) as a modification upregulated in CRC, which had not been shown previously.
The present results indicate the usefulness of a bottom-up proteomic approach for the detection of histone modifications at a global scale. The differential abundance of H3K27Ac mark in CRC, a PTM associated with active enhancers, suggests its role in regulating genes whose expression changes in CRC.
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ABSTRACT: Epigenetic regulation of gene expression has provided colorectal cancer (CRC) pathogenesis with an additional trait during the past decade. In particular, histone post-translational modifications set up a major component of this process dictating chromatin status and recruiting non-histone proteins in complexes formed to "handle DNA". In CRC, histone marks of aberrant acetylation and methylation levels on specific residues have been revealed, along with a plethora of deregulated enzymes that catalyze these reactions. Mutations, deletions or altered expression patterns transform the function of several histone-modifying proteins, further supporting the crucial role of epigenetic effectors in CRC oncogenesis, being closely associated to inactivation of tumor suppressor genes. Elucidation of the biochemical basis of these new tumorigenic mechanisms allows novel potential prognostic factors to come into play. Moreover, the detection of these changes even in early stages of the multistep CRC process, along with the reversible nature of these mechanisms and the technical capability to detect such alterations in cancer cells, places this group of covalent modifications as a further potential asset for clinical diagnosis or treatment of CRC. This review underlines the biochemistry of histone modifications and the potential regulatory role of histone-modifying proteins in CRC pathogenesis, to date. Furthermore, the underlying mechanisms of the emerging epigenetic interplay along with the chemical compounds that are candidates for clinical use are discussed, offering new insights for further investigation of key histone enzymes and new therapeutic targets.
Available from: Muin J Khoury
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ABSTRACT: BACKGROUND: Remarkable progress has been made in the last decade in new methods for biological measurements using sophisticated technologies that go beyond the established genome, proteome, and gene expression platforms. These methods and technologies create opportunities to enhance cancer epidemiologic studies. In this article, we describe several emerging technologies and evaluate their potential in epidemiologic studies. We review the background, assays, methods, and challenges, and offer examples of the use of mitochondrial DNA and copy number assessments, epigenomic profiling (including methylation, histone modification, microRNAs (miRNAs), and chromatin condensation), metabolite profiling (metabolomics), and telomere measurements. We map the volume of literature referring to each one of these measurement tools and the extent to which efforts have been made at knowledge integration (e.g. systematic reviews and meta-analyses). We also clarify strengths and weaknesses of the existing platforms and the range of type of samples that can be tested with each of them. These measurement tools can be used in identifying at-risk populations and providing novel markers of survival and treatment response. Rigorous analytical and validation standards, transparent availability of massive data, and integration in large-scale evidence are essential in fulfilling the potential of these technologies.
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