Repression of KIAA1199 attenuates Wnt-signalling and decreases the proliferation of colon cancer cells.

BACKGROUND: The KIAA1199 transcript is upregulated in colon adenomas and downregulated upon ß-catenin knockdown. METHODS: Transcript profiling was performed on >500 colon biopsies, methylation profiling data were compared with transcript data. Immunohistochemistry assessed KIAA1199 protein expression in 270 stage II/III tumours (>3 years follow-up). The effects of stable KIAA1199 knockdown in SW480 cells (three different constructs) were studied using transcriptional profiling, proliferation and protein analysis. RESULTS: The KIAA1199 transcript was strongly upregulated in 95% of adenocarcinomas. Absent expression in normal mucosa correlated with KIAA1199 promotor methylation. Nuclear and cytoplasmic KIAA1199 protein expression was identified in colon adenocarcinomas and other types of cancers. A subpopulation of patients with tumours strongly expressing KIAA1199 in the nucleus showed a better outcome with regard to recurrence as lung or liver metastases. The KIAA1199 knockdown affected the cell cycle and the Wnt-signalling pathway. Reduced cellular proliferation and decreased KI67, phosphorylated retinoblastoma, ß-catenin and ASCL2 protein expression supported these findings. Eighteen Wnt-signalling genes differentially expressed upon KIAA1199 knockdown correlated with the KIAA1199 expression profile in clinical specimens. CONCLUSION: The KIAA1199 knockdown attenuates the effects of the Wnt/ß-catenin signalling and it may thus be regarded as a regulatory part of this pathway.

Low ANXA10 expression is associated with disease aggressiveness in bladder cancer.

BACKGROUND: Markers for outcome prediction in bladder cancer are urgently needed. We have previously identified a molecular signature for predicting progression in non-muscle-invasive bladder cancer. ANXA10 was one of the markers included in the signature and we now validated the prognostic relevance of ANXA10 at the protein level. METHODS: We investigated ANXA10 expression by immunohistochemistry using a tissue microarray with 249 Ta and T1 urothelial carcinomas. The expression of ANXA10 was also investigated in an additional set of 97 more advanced tumours. The functional role of ANXA10 in cell lines was investigated by siRNA-mediated ANXA10 knockdown using wound-healing assays, proliferation assays, and ingenuity pathway analysis. RESULTS: Low expression of ANXA10 correlated with shorter progression-free survival in patients with stage Ta and T1 tumours (P<0.00001). Furthermore, patients with more advanced tumours and low ANXA10 expression had an unfavourable prognosis (P<0.00001). We found that ANXA10 siRNA transfected cells grew significantly faster compared with control siRNA transfected cells. Furthermore, a wound-healing assay showed that ANXA10 siRNA transfected cells spread along wound edges faster than control transfected cells. CONCLUSION: We conclude that ANXA10 may be a clinical relevant marker for predicting outcome in both early and advanced stages of bladder cancer.

No evidence of somatic aryl hydrocarbon receptor interacting protein mutations in sporadic endocrine neoplasia.

Germline mutations in the aryl hydrocarbon receptor interacting protein (AIP) gene were recently observed in patients with pituitary adenoma predisposition (PAP). Though AIP mutation-positive individuals with prolactin-, mixed growth hormone/prolactin-, and ACTH-producing pituitary adenomas as well as non-secreting pituitary adenomas have been reported, most mutation-positive patients have had growth hormone-producing adenomas diagnosed at relatively young age. Pituitary adenomas are also component tumors of some familial endocrine neoplasia syndromes such as multiple endocrine neoplasia type 1 (MEN1) and Carney complex (CNC). Genes underlying MEN1 and CNC are rarely mutated in sporadic pituitary adenomas, but more often in other lesions contributing to these two syndromes. Thus far, the occurrence of somatic AIP mutations has not been studied in endocrine tumors other than pituitary adenomas. Here, we have analyzed 32 pituitary adenomas and 79 other tumors of the endocrine system for somatic AIP mutations by direct sequencing. No somatic mutations were identified. However, two out of nine patients with prolactin-producing adenoma were shown to harbor a Finnish founder mutation (Q14X) with a complete loss of the wild-type allele in the tumors. These results are in agreement with previous studies in that prolactin-producing adenomas are component tumors in PAP. The data also support the previous finding that somatic AIP mutations are not common in pituitary adenomas and suggest that such mutations are rare in other endocrine tumors as well.

Inhibition of Holliday structure resolving endonuclease VII of bacteriophage T4 by recombination enzymes UvsX and UvsY.

Proteins UvsX, UvsY and Endonuclease VII (Endo VII) of bacteriophage T4 are required for DNA recombination, replication and repair. Endo VII is the product of gene 49 (gp49) and essential for resolution of branches from newly made DNA, prior to packaging into preformed heads. The ability of Endo VII to resolve Holliday structures in vitro suggested an in vivo function for the resolution of recombination intermediates, generated by UvsX and UvsY during the early infection cycle. Here we report results which contrast with this hypothesis. It is shown that the potent endonucleolytic activity of Endo VII with branched DNAs is inhibited in strand transfer reactions by the strand transferase UvsX, and more strongly by the accessory protein UvsY in vitro. The inhibitory effect of UvsX or UvsY is also seen in reactions with Endo VII using two synthetic cruciform DNAs and a C/C-mismatch containing substrate. Low concentrations of UvsY protein (12 ng or 0,76 pmol) were sufficient to reduce the cleavage efficiency of 30 units of Endo VII (about 16 fmol) to 50%. The inhibition is due to a direct protein-protein interaction between Endo VII, UvsX and UvsY as suggested by electrophoretic mobility shift assays (EMSAs). These results were confirmed through affinity chromatography, where UvsX and UvsY bound to Endo VII, immobilized on a NHS-activated Sepharose matrix. This is the first identification of phage-encoded proteins which modulate the potent endonucleolytic activity of gp49 in vitro.

Another view of myocardial hibernation.

This manuscript brings together three newer concepts: myocardial hibernation, heterogeneity in myocardial blood flow and oxidative metabolism, and effects of hibernating animal serum on non-hibernators. Myocardial hibernation is viewed as a protective mechanism that helps to maintain myocardial integrity and viability by down-regulating contractile function as an adaptation to reduced blood flow. Myocardial flow is considerably heterogeneous. Consequently, oxygen supply to the myocardium is also heterogeneous. Many lines of evidence show a close correlation between regional flow and regional metabolism. In low-flow/low-metabolism areas, myocardial function must be reduced, since the myocardium would otherwise undergo necrosis. Because no regional histological differences exist, the pattern of heterogeneity seems to shift over time. Hence, we hypothesize that such very regional hibernation presents an evolutionary, protective mechanism, permitting subsequent myocardial areas to rest within the ceaselessly working heart. We also hypothesize that a similar mechanism ensures the down-regulation of function following myocardial ischemia in order to induce myocardial hibernation on a broader level. Surprisingly, a substance (opioid in nature) contained in hibernator serum both induced hibernation-like state in non-hibernators and suppressed myocardial oxygen consumption. Thus, we lastly hypothesize that myocardial hibernation is a remnant of the early stages of evolution and is closer to physiological hibernation than traditionally viewed.

Differential expression of DHHC9 in microsatellite stable and instable human colorectal cancer subgroups.

Microarray analysis on pooled samples has previously identified ZDHHC9 (DHHC9) to be upregulated in colon adenocarcinoma compared to normal colon mucosa. Analyses of 168 samples from proximal and distal adenocarcinomas using U133plus2.0 microarrays validated these findings, showing a significant two-fold (log 2) upregulation of DHHC9 transcript (P<10(-6)). The upregulation was more striking in microsatellite stable (MSS), than in microsatellite instable (MSI), tumours. Genes known to interact with DHHC9 as H-Ras or N-Ras did not show expression differences between MSS and MSI. Immunohistochemical analysis was performed on 60 colon adenocarcinomas, previously analysed on microarrays, as well as on tissue microarrays with 40 stage I-IV tumours and 46 tumours from different organ sites. DHHC9 protein was strongly expressed in MSS compared to MSI tumours, readily detectable in premalignant lesions, compared to the rare expression seen in normal mucosa. DHHC9 was specific for tumours of the gastrointestinal tract and localised to the Golgi apparatus, in vitro and in vivo. Overexpression of DHHC9 decreased the proliferation of SW480 and CaCo2 MSS cell lines significantly. In conclusion, DHHC9 is a gastrointestinal-related protein highly expressed in MSS colon tumours. The palmitoyl transferase activity, modifying N-Ras and H-Ras, suggests DHHC9 as a target for anticancer drug design.

Differential gene expression in colon cancer of the caecum versus the sigmoid and rectosigmoid.

BACKGROUND AND AIMS: There are epidemiological, morphological, and molecular differences between normal mucosa as well as between adenocarcinomas of the right and left side of the large bowel. The aim of this study was to investigate differences in gene expression. METHODS: Oligonucleotide microarrays (GeneChip) were used to compare gene expression in 45 single samples from normal mucosa and sporadic colorectal carcinomas (Dukes' B and C) of the caecum compared with the sigmoid and rectosigmoid. Findings were validated by real time polymerase chain reaction. RESULTS: Fifty eight genes were found to be differentially expressed between the normal mucosa of the caecum and the sigmoid and rectosigmoid (p<0.01), including pS2, S100P, and a sialyltransferase, all being expressed at higher levels in the caecum. A total of 118 and 186 genes were differentially expressed between normal and right or left sided tumours of the colon, showing more pronounced differences in Dukes' C than B tumours. Thirty genes differentially expressed in tumour tissue were common to adenocarcinomas of both sides, including known tumour markers such as the matrix metalloproteinases. Keratins 8, 19, and 20 as well as carbonic anhydrases (II, IV, VII) showed side specific expression and were downregulated in left sided tumours whereas teratocarcinoma growth factor and cyclooxygenase 2 (COX-2) were upregulated in left sided adenocarcinomas. Immunohistochemical analysis confirmed differences in side specific expression for cytokeratin 20 and COX-2. CONCLUSIONS: Differences in gene expression between normal mucosa as well as between adenocarcinomas of the caecum and sigmoid or rectosigmoid exist and should be taken into account when examining new targeted therapeutic regimens.

Gene expression signatures for colorectal cancer microsatellite status and HNPCC.

The majority of microsatellite instable (MSI) colorectal cancers are sporadic, but a subset belongs to the syndrome hereditary non-polyposis colorectal cancer (HNPCC). Microsatellite instability is caused by dysfunction of the mismatch repair (MMR) system that leads to a mutator phenotype, and MSI is correlated to prognosis and response to chemotherapy. Gene expression signatures as predictive markers are being developed for many cancers, and the identification of a signature for MMR deficiency would be of interest both clinically and biologically. To address this issue, we profiled the gene expression of 101 stage II and III colorectal cancers (34 MSI, 67 microsatellite stable (MSS)) using high-density oligonucleotide microarrays. From these data, we constructed a nine-gene signature capable of separating the mismatch repair proficient and deficient tumours. Subsequently, we demonstrated the robustness of the signature by transferring it to a real-time RT-PCR platform. Using this platform, the signature was validated on an independent test set consisting of 47 tumours (10 MSI, 37 MSS), of which 45 were correctly classified. In a second step, we constructed a signature capable of separating MMR-deficient tumours into sporadic MSI and HNPCC cases, and validated this by a mathematical cross-validation approach. The demonstration that this two-step classification approach can identify MSI as well as HNPCC cases merits further gene expression studies to identify prognostic signatures.

Identification of amino acids of endonuclease VII essential for binding and cleavage of cruciform DNA.

Endonuclease VII is a Holliday-structure-resolving enzyme of bacteriophage T4. The active protein is a homodimer with 157 amino acids/monomer. An amber mutation (amE727 in codon 151) inactivates the nuclease completely, indicating the importance of the seven C-terminal amino acids for nucleolytic activity. The influence of these amino acids on cruciform-DNA binding and cleavage was investigated through functional analysis of C-terminal-truncated proteins derived from deletion constructs. It was found that the three C-terminal amino acids are not necessary for binding and cleavage. A transition from active to inactive protein occurs gradually with truncations of the next four amino acids. Reduction of DNA-binding ability, as measured by electrophoretic mobility shift assays, was determined to be the primary defect in the cleavage-deficient proteins. This was further concluded by the finding that EVII-(1-150)-peptide(amber), a protein with fairly low affinity to cruciform DNA, contributes cleavage activity to reactions of wild-type EVII with cruciform DNA. [Asp62]EVII-(1-156)-peptide lacking one C-terminal amino acid, contains a point mutation in codon 62 that eliminates the nucleolytic activity of the protein while retaining its DNA-binding proficiency. By mixing binding-deficient and cleavage-deficient mutants in the same assay, cleavage of cruciform DNA resumed. Evidence is presented that complementation occurs by heterodimer formation. Our results show that the zinc-binding motif of EVII is not sufficient for cruciform-DNA binding.

Enzymatic mutation detection. Procedure for screening and mapping of mutations by immobilised endonuclease VII.

Endonuclease VII (endo VII) binds to non-pairing nucleotides in DNA. This served as the basis for the development of a mutation detection assay involving immobilised endo VII and heteroduplex DNAs made by hybridisation of mutant and wild type DNA. The use of microtiter plates allows screening of large numbers of samples. Localisation of mutations in positive samples can be done in the same assay in a second optional step.

[Myocardial hibernation: another view]. / Myokardiale Hibernation: eine andere Sicht.

In the following, three newer concepts are brought together: myocardial hibernation, heterogeneity in myocardial blood flow and oxidative metabolism, and effects of hibernating animal serum on non-hibernators. Myocardial hibernation is viewed as a protective mechanism that helps to maintain myocardial integrity and viability by down-regulating contractile function as an adaptation to reduced blood flow. Myocardial flow is considerably heterogeneous. Consequently, oxygen supply to the myocardium is also heterogeneous. Many lines of evidence show a close correlation between regional flow and regional metabolism. In low-flow/low-metabolism areas, myocardial function must be reduced, since the myocardium would otherwise undergo necrosis. Thus, others and we hypothesize that function must be down-regulated to induce hibernation in low-flow areas. Because no regional histologic differences exist (the mitochondria are uniformly distributed within the myocardium), the pattern of heterogeneity seems to shift over time. Hence, we hypothesize that such very regional hibernation presents an evolutionary, protective mechanism, permitting subsequent myocardial areas to rest within the ceaselessly working heart. We also hypothesize that this mechanism ensures the down-regulation of function following myocardial ischemia in order to induce myocardial hibernation on a broader level. Surprisingly, a substance (opioid in nature) contained in hibernator serum both induced hibernation-like state in non-hibernators and suppressed myocardial oxygen consumption. Thus, we lastly hypothesize that myocardial hibernation is a remnant of the early stages of evolution and is closer to physiologic hibernation than traditionally viewed.