Post-translational histone modifications are known to be altered in cancer cells, and loss of selected histone acetylation and methylation marks has recently been shown to predict patient outcome in human carcinoma. Immunohistochemistry was used to detect a series of histone lysine acetylation (H3K9ac, H3K18ac, H4K12ac, and H4K16ac), lysine methylation (H3K4me2 and H4K20me3), and arginine methylation (H4R3me2) marks in a well-characterized series of human breast carcinomas (n = 880). Tissue staining intensities were assessed using blinded semiquantitative scoring. Validation studies were done using immunofluorescence staining and Western blotting. Our analyses revealed low or absent H4K16ac in the majority of breast cancer cases (78.9%), suggesting that this alteration may represent an early sign of breast cancer. There was a highly significant correlation between histone modifications status, tumor biomarker phenotype, and clinical outcome, where high relative levels of global histone acetylation and methylation were associated with a favorable prognosis and detected almost exclusively in luminal-like breast tumors (93%). Moderate to low levels of lysine acetylation (H3K9ac, H3K18ac, and H4K12ac), lysine (H3K4me2 and H4K20me3), and arginine methylation (H4R3me2) were observed in carcinomas of poorer prognostic subtypes, including basal carcinomas and HER-2-positive tumors. Clustering analysis identified three groups of histone displaying distinct pattern in breast cancer, which have distinct relationships to known prognostic factors and clinical outcome. This study identifies the presence of variations in global levels of histone marks in different grades, morphologic types, and phenotype classes of invasive breast cancer and shows that these differences have clinical significance. [Cancer Res 2009;69(9):3802-9]

The DNA damage response activates several pathways that stall the cell cycle and allow DNA repair. These consist of the wellcharacterized ATR (Ataxia telangiectasia and Rad-3 related)/ CHK1 and ATM (Ataxia telangiectasia mutated)/CHK2 pathways in addition to a newly identified ATM/ATR/p38MAPK/MK2 checkpoint. Crucial to maintaining the integrity of the genome is the Sphase checkpoint that functions to prevent DNA replication until damaged DNA is repaired. Inappropriate expression of the proto-oncogene c-Myc is known to cause DNA damage. One mechanism by which c-Myc induces DNA damage is through binding directly to components of the prereplicative complex thereby promoting DNA synthesis, resulting in replication-associated DNA damage and checkpoint activation due to inappropriate origin firing. Here we show that following etoposide-induced DNA damage translation of c-Myc is repressed by miR-34c via a highly conserved target-site within the 3 0 UTR. While miR-34c is induced by p53 following DNA damage, we show that in cells lacking p53 this is achieved by an alternative pathway which involves p38 MAPK signalling to MK2. The data presented here suggest that a major physiological target of miR-34c is c-Myc. Inhibition of miR-34c activity prevents S-phase arrest in response to DNA damage leading to increased DNA synthesis, DNA damage, and checkpoint activation in addition to that induced by etoposide alone, which are all reversed by subsequent c-Myc depletion. These data demonstrate that miR34c is a critical regulator of the c-Myc expression following DNA damage acting downstream of p38 MAPK/MK2 and suggest that miR-34c serves to remove c-Myc to prevent inappropriate replication which may otherwise lead to genomic instability.

There is now strong evidence that MMPs play a major role in tumour invasion and metastasis. The development of MMP inhibitors may lead to important new treatment for the control of malignant disease.

There is now strong evidence that MMPs play a major role in tumour invasion and metastasis. The development of MMP inhibitors may lead to important new treatment for the control of malignant disease.

Histone tail modifications control many nuclear processes by dictating the dynamic exchange of regulatory proteins on chromatin. Here we report novel insights into histone H3 tail structure in complex with the double PHD finger (DPF) of the lysine acetyltransferase MOZ/MYST3/KAT6A. In addition to sampling H3 and H4 modification status, we show that the DPF cooperates with the MYST domain to promote H3K9 and H3K14 acetylation, although not if H3K4 is trimethylated. Four crystal structures of an extended DPF alone and in complex with unmodified or acetylated forms of the H3 tail reveal the molecular basis of crosstalk between H3K4me3 and H3K14ac. We show for the first time that MOZ DPF induces α-helical conformation of H3K4-T11, revealing a unique mode of H3 recognition. The helical structure facilitates sampling of H3K4 methylation status, and proffers H3K9 and other residues for modification. Additionally, we show that a conserved double glycine hinge flanking the H3 tail helix is required for a conformational change enabling docking of H3K14ac with the DPF. In summary, our data provide the first observations of extensive helical structure in a histone tail, revealing the inherent ability of the H3 tail to adopt alternate conformations in complex with chromatin regulators.

Summary The aim of the study was to investigate expression of the active and inactive gelatinases (MMP-2 and -9) in colorectal neoplasia and gastric cancer compared with normal mucosa. A total of 53 colorectal cancers and corresponding normal mucosa were studied using gelatin zymography as well as 15 colorectal adenomas and 13 gastric cancers with corresponding normal mucosa. Overexpression of all the gelatinases occurs in both colorectal and gastric cancer, with activation of MMP-2 appearing to be a feature of the malignant phenotype. Overexpression of MMP-9 occurs in colorectal adenomas. The gelatinases are overexpressed in gastrointestinal neoplasia, suggesting that these enzymes may have an important role in tumour invasion and metastasis.

In vivo, CBP associates with subnuclear structures called PML bodies, which contain the structural component PML and at least 10 other proteins such as Sp100 (66). Both CBP and its homolog p300 function in cell proliferation, differentiation, and apoptosis (7, 21). Studies with heterozygous null mice have demonstrated a requirement for CBP in normal hematopoiesis. CBP-null embryos were found to have defective hematopoiesis (44, 65), whereas mice heterozygous for the CBP gene developed a range of hematopoietic diseases (33) and showed reduced self-renewal of hematopoietic stem cells (51). Moreover, genetic abnormalities involving the CBP/p300 genes in acute myeloid leukemia (AML) provide further evidence for their role in the regulation of hematopoietic development.Reciprocal translocations fusing genes encoding monocytic leukemia zinc finger protein (MOZ/MYST3) or MOZ-related factor (MORF/MYST4) to CBP (8, 48), p300 (10) or transcriptional intermediary factor TIF2 (1,6,9,15,36,42,47) are recurrent in the M4 and M5 subtypes of AML. MOZ is a member of the MOZ/YBF2/SAS2/TIP60 homology domain (MYST) family of protein acetyltransferases, which contain a C2HC zinc finger and acetyltransferase domain that together comprise the MYST domain (64). MOZ and MORF acetylate histones in vitro but share little sequence homology with other MYST proteins outside the histone acetyltransferase (HAT) domain, suggesting diverse cellular functions for this family (56, 64). MOZ was reported to modestly enhance reporter activation by Runx domain proteins such as AML1, although this activity was not dependent on its histone acetyltransferase activity (11,12,32). Thus, while it is likely to have a role in chromatin modification, the function of MOZ in vivo remains to be established. TIF2/GRIP1 (24, 62) is a member of the p160 family of coactivators, which also includes SRC1 (28, 46) and ACTR/ pCIP/AIB1 (4, 13, 60). These proteins function as coactivators for nuclear receptors (NRs) and associate tightly with NRs via LXXLL motifs (23, 60). The C termini of p160 proteins contain the AD1 and AD2 domains, which recruit CBP/p300 and CARM-1, respectively, to NR target promoters (13,24,28,31,54,62). A leucine-rich ␣-helix in AD-1 (17, 54) is conserved in Ets-2, IRF3, p53, and E1A proteins, which compete with p160s for binding to the C terminus of CBP (39).The t(8:16)(p11;p13) translocation produces a fusion protein containing the N terminus of MOZ (amino acids 1 to 1547) and almost the entire sequence of CBP (amino acids 244 to 2441) (8). MOZ-TIF2 translocations derive from inversions of chromosome 8, inv8(p11q13) (42), and give rise to fusion proteins containing the N terminus of MOZ, including the plant homeodomain and MYST domains (amino acids 1 to 1117) and the C terminus of TIF2 (amino acids 869 to 1713 or 939 to 1713), including AD1 and AD2. The acquisition of MOZ-CBP and MOZ-TIF2 translocations is likely to affect cell function in a number of ways, including (i) a reduction of the normal cellular complement of parental proteins and (ii) a...

Background and aims: Matrix metalloproteinase-7 (MMP-7) is important in normal and pathological remodelling of epithelial-matrix interactions, and is upregulated in gastric cancer. Helicobacter pylori infection is the first stage in gastric carcinogenesis, and therefore our aim was to determine if H pylori upregulated gastric MMP-7 expression and if this was affected by strain virulence. Methods: We took gastric biopsy specimens at endoscopy from H pylori infected (n = 17) and uninfected (n = 18) patients and assessed MMP-7 expression by ELISA, real time polymerase chain reaction (PCR), and immunohistochemistry (concentrating on epithelial cells in the proliferative zone). We PCR typed H pylori for cagE and vacA. We performed H pylori/cell line coculture studies with wild-type pathogenic and non-pathogenic H pylori strains and with CagE 2 and VacA 2 isogenic mutants. Results: Gastric biopsy specimens from H pylori+ patients expressed higher levels of MMP-7 at the protein and mRNA levels in the antrum and corpus (for example, by ELISA: H pylori+ 0.182 OD units v H pylori2 0.059; p = 0.009 antrum). Epithelial cells from H pylori+ patients stained more intensely for MMP-7 than those from uninfected patients, including in the proliferative zone containing pluripotent cells (p,0.03 antrum, p,0.04 body). Upregulation of MMP-7 in epithelial cells was confirmed at the protein and mRNA levels by H pylori/cell line coculture. These experiments also showed that MMP-7 upregulation was dependent on an intact H pylori cag pathogenicity island but not on the vacuolating cytotoxin. Conclusion: We speculate that increased expression of MMP-7 in H pylori gastritis may contribute to gastric carcinogenesis.