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  • 1
    Abstract: Little is known about histone modifiers and histone marks in colorectal cancers (CRC). The present study therefore addressed the role of histone acetylation and histone deacetylases (HDAC) in CRCs in situ and in vitro. Immunohistochemistry of primary CRCs (n=47) revealed that selected histone marks were frequently present (H3K4me3: 100%; H3K9me3: 77%; H3K9ac: 75%), partially displayed intratumoral heterogeneity (H3K9me3; H3K9ac) and were significantly linked to higher pT category (H3K9me3: p=0.023; H3K9ac: p=0.028). Furthermore, also HDAC1 (62%), HDAC2 (100%) and HDAC3 (72%) expression was frequent, revealing four CRC types: cases expressing 1) HDAC1, HDAC2 and HDAC3 (49%), 2) HDAC2 and HDAC3 (30%), 3) HDAC1 and HDAC2 (10.5%) and 4) exclusively HDAC2 (10.5%). Correlation to clinico-pathological parameters (pT, pN, G, MSI status) revealed that heterogeneous HDAC1 expression correlated with lymph node status (p=0.012). HDAC expression in situ was partially reflected by six CRC cell lines, with similar expression of all three HDACs (DLD1, LS174T), preferential HDAC2 and HDAC3 expression (SW480, Caco2) or lower HDAC2 and HDAC3 expression (HCT116, HT29). HDAC activity was variably higher in HCT116, HT29, DLD1 and SW480 compared to LS174T and Caco2 cells. Treatment with broad (SAHA) and specific (MS-275; FK228) HDAC inhibitors (HDACi) caused loss of cell viability in predominantly MSIpositive CRC cells (HCT116, LS174T, DLD1; SAHA, MS-275 and in part FK228). In contrast, MSI-negative CRC cells (Caco2, HT29, SW480) were resistant, except for high doses of FK228 (Caco2, HT29). Cell viability patterns were not linked to different efficacies of HDACi on reduction of HDAC activity or histone acetylation, p21 expression and/or induction of DNA damage (gammaH2A-X levels). In summary, this study reveals inter- and intra-tumoral heterogeneity of histone marks and HDAC expression in CRCs. This is reflected by diverse HDACi responses in vitro, which do not follow known modes of action. Together, this implies further exploitation of histone alterations in CRC for molecular classification and/or novel treatment options.
    Type of Publication: Journal article published
    PubMed ID: 27152243
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  • 2
    Keywords: EXPRESSION ; PROGRESSION ; COLON-CANCER ; METAANALYSIS ; TARGET GENES ; APC ; MICROSATELLITE-INSTABILITY
    Abstract: The majority of sporadic forms of colorectal carcinomas is characterized by deregulation of Wnt/beta-catenin signaling early in colorectal carcinogenesis. As a consequence, ITF-2B protein levels are increased in adenomas of these patients. However, ITF-2B protein levels are strongly reduced with increasing carcinoma stages, suggesting that reduction of ITF-2B protein is required for progression of adenomas to colorectal carcinomas. To find out if ITF-2B protein levels are correlated with the survival of patients with colorectal carcinomas, a tissue microarray containing samples from 213 colorectal carcinomas (T-categories T2 and T3) with corresponding survival information was stained with an ITF-2B antibody. In addition, we analyzed if detection of ITF-2B in microsatellite instable and microsatellite stable carcinomas as well as in colorectal carcinomas with KRAS mutations is correlated with survival. Detection of cytoplasmic ITF-2B protein was associated with better overall and progression free survival of patients with colorectal carcinomas (P=0.033 and 0.024, respectively). Multivariate Cox regression analysis revealed an increased risk to suffer from poor overall survival and recurrent disease if no cytoplasmic ITF-2B was detectable (HR=1.91; P=0.033 and HR=1.75; P=0.033, respectively). Similarly, patients with MSS carcinomas had a better overall survival, if they showed cytoplasmic positivity for ITF-2B (P=0.013). Remarkably, patients with colorectal carcinomas carrying KRAS mutations had a better overall and progression free survival rate if the carcinomas were positive for cytoplasmic ITF-2B (HR=4.71; P=0.002 and HR=2.57; P=0.024, respectively). These data suggest that cytoplasmic protein levels of ITF-2B could be used as a prognostic marker for patients with colorectal carcinomas.
    Type of Publication: Journal article published
    PubMed ID: 26328254
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