Interactome of intact chromatosome variants with site-specifically ubiquitylated and acetylated linker histone H1.2.

Post-translational modifications (PTMs) of histones have fundamental effects on chromatin structure and function. While the impact of PTMs on the function of core histones are increasingly well understood, this is much less the case for modifications of linker histone H1, which is at least in part due to a lack of proper tools. In this work, we establish the assembly of intact chromatosomes containing site-specifically ubiquitylated and acetylated linker histone H1.2 variants obtained by a combination of chemical biology approaches. We then use these complexes in a tailored affinity enrichment mass spectrometry workflow to identify and comprehensively characterize chromatosome-specific cellular interactomes and the impact of site-specific linker histone modifications on a proteome-wide scale. We validate and benchmark our approach by western-blotting and by confirming the involvement of chromatin-bound H1.2 in the recruitment of proteins involved in DNA double-strand break repair using an in vitro ligation assay. We relate our data to previous work and in particular compare it to data on modification-specific interaction partners of free H1. Taken together, our data supports the role of chromatin-bound H1 as a regulatory protein with distinct functions beyond DNA compaction and constitutes an important resource for future investigations of histone epigenetic modifications.

Chemical synthesis of 2″OMeNAD+ and its deployment as an RNA 2'-phosphotransferase (Tpt1) 'poison' that traps the enzyme on its abortive RNA-2'-PO4-(ADP-2″OMe-ribose) reaction intermediate.

RNA 2'-phosphotransferase Tpt1 catalyzes the removal of an internal RNA 2'-PO4 via a two-step mechanism in which: (i) the 2'-PO4 attacks NAD+ C1″ to form an RNA-2'-phospho-(ADP-ribose) intermediate and nicotinamide; and (ii) transesterification of the ADP-ribose O2″ to the RNA 2'-phosphodiester yields 2'-OH RNA and ADP-ribose-1″,2″-cyclic phosphate. Although Tpt1 enzymes are prevalent in bacteria, archaea, and eukarya, Tpt1 is uniquely essential in fungi and plants, where it erases the 2'-PO4 mark installed by tRNA ligases during tRNA splicing. To identify a Tpt1 'poison' that arrests the reaction after step 1, we developed a chemical synthesis of 2″OMeNAD+, an analog that cannot, in principle, support step 2 transesterification. We report that 2″OMeNAD+ is an effective step 1 substrate for Runella slithyformis Tpt1 (RslTpt1) in a reaction that generates the normally undetectable RNA-2'-phospho-(ADP-ribose) intermediate in amounts stoichiometric to Tpt1. EMSA assays demonstrate that RslTpt1 remains trapped in a stable complex with the abortive RNA-2'-phospho-(ADP-2″OMe-ribose) intermediate. Although 2″OMeNAD+ establishes the feasibility of poisoning and trapping a Tpt1 enzyme, its application is limited insofar as Tpt1 enzymes from fungal pathogens are unable to utilize this analog for step 1 catalysis. Analogs with smaller 2″-substitutions may prove advantageous in targeting the fungal enzymes.

A dual-purpose polymerase engineered for direct sequencing of pseudouridine and queuosine.

More than 170 posttranscriptional RNA modifications are so far known on both coding and noncoding RNA species. Within this group, pseudouridine (Ψ) and queuosine (Q) represent conserved RNA modifications with fundamental functional roles in regulating translation. Current detection methods of these modifications, which both are reverse transcription (RT)-silent, are mostly based on the chemical treatment of RNA prior to analysis. To overcome the drawbacks associated with indirect detection strategies, we have engineered an RT-active DNA polymerase variant called RT-KTq I614Y that produces error RT signatures specific for Ψ or Q without prior chemical treatment of the RNA samples. Combining this polymerase with next-generation sequencing techniques allows the direct identification of Ψ and Q sites of untreated RNA samples using a single enzymatic tool.

17p13 (TP53) Deletions Are Associated With an Aggressive Phenotype but Unrelated to Patient Prognosis in Urothelial Bladder Carcinomas.

17p13 deletions including TP53 and other genes represent a common cause for reduced/lost p53 function in tumor cells. In this study, we analyzed the impact of 17p13 (TP53) deletions and p53 expression on tumor aggressiveness and patient prognosis in urothelial carcinoma. The 17p13 copy number status was analyzed by fluorescence in situ hybridization (FISH) on more than 2700 urothelial bladder carcinomas in a tissue microarray format. 17p13 deletion data were compared to p53 expression data measured by immunohistochemistry (IHC) in a previous study. Different types of p53 alterations were compared with tumor phenotype and clinical outcome data. Deletions of 17p13 occurred in 23% of 2185 analyzable carcinomas. The fraction of tumors with 17p13 deletions increased from pTa G2 low (9%) to pTa G3 (24%, p < 0.0001). In muscle-invasive carcinomas, 17p13 deletions were associated with advanced pT stage (p = 0.0246), but unrelated to patient prognosis (p > 0.5). 17p13 deletions were significantly related to p53 immunostaining (p = 0.0375). 17p13 deletions were most common in tumors with complete lack of p53 staining (31%), which supports the concept that many of these tumors have a complete loss of p53 function (p53 null phenotype). 17p13 deletions were also increased in tumors with high p53 staining (25%). In conclusion, 17p13 deletions were most commonly seen in p53 negative cancers, supporting their role as a cause for the p53 null phenotype in urothelial cancer. The association of 17p13 deletions with high grade and advanced pT stage may reflect increasing genomic instability going along with stage and grade progression.

A desthiobiotin labelled NAD+ analogue to uncover Poly(ADP-ribose) polymerase 1 protein targets.

ADP-ribosylation is a post-translational modification catalyzed by the enzyme family of polyadenosine diphosphate (ADP)-ribose) polymerases (PARPs). This enzymatic process involves the transfer of single or multiple ADP-ribose molecules onto proteins, utilizing nicotinamide adenine dinucleotide (NAD+ ) as a substrate. It, thus, plays a pivotal role in regulating various biological processes. Unveiling PARP-selective protein targets is crucial for a better understanding of their biological functions. Nonetheless, this task proves challenging due to overlapping targets shared among PARP family members. Therefore, we applied the "bump-and-hole" strategy to modify the nicotinamide binding site of PARP1 by introducing a hydrophobic pocket ("hole"). This PARP1-mutant binds an orthogonal NAD+ (Et-DTB-NAD+ ) containing an ethyl group ("bump") at the nicotinamide moiety. Furthermore, we added a desthiobiotin (DTB) tag directly to the adenosine moiety, enabling affinity enrichment of ADP-ribosylated proteins. Employing this approach, we successfully identified protein targets modified by PARP1 in cell lysate. This strategy expands the arsenal of chemically modified NAD+ analogs available for studying ADP-ribosylation, providing a powerful tool to study these critical post-translational modifications.

Biochemical and Structural Consequences of NEDD8 Acetylation.

Similar to ubiquitin, the ubiquitin-like protein NEDD8 is not only conjugated to other proteins but is itself subject to posttranslational modifications including lysine acetylation. Yet, compared to ubiquitin, only little is known about the biochemical and structural consequences of site-specific NEDD8 acetylation. Here, we generated site-specifically mono-acetylated NEDD8 variants for each known acetylation site by genetic code expansion. We show that, in particular, acetylation of K11 has a negative impact on the usage of NEDD8 by the NEDD8-conjugating enzymes UBE2M and UBE2F and that this is likely due to electrostatic and steric effects resulting in conformational changes of NEDD8. Finally, we provide evidence that p300 acts as a position-specific NEDD8 acetyltransferase.

KLK7 expression in human tumors: a tissue microarray study on 13,447 tumors.

BACKGROUND: Kallikrein-related peptidase 7 (KLK7) is a chymotrypsin-like serine protease which is essential for the desquamation of corneocytes and thus plays a pivotal role in maintaining skin homeostasis. In cancer, KLK7 overexpression was suggested to represent a route for metastasis through cleavage of cell junction and extracellular matrix proteins of cancer cells. METHODS: To comprehensively determine KLK7 protein expression in normal and neoplastic tissues, a tissue microarray containing 13,447 samples from 147 different tumor types and subtypes as well as 608 samples of 76 different normal tissue types was analyzed by immunohistochemistry. RESULTS: KLK7 positivity was found in 64 of 147 tumor categories, including 17 tumor categories with at least one strongly positive case. The highest rate of KLK7 positivity was found in squamous cell carcinomas from various sites of origin (positive in 18.1%-63.8%), ovarian and endometrium cancers (4.8%-56.2%), salivary gland tumors (4.8%-13.7%), bilio-pancreatic adenocarcinomas (20.0%-40.4%), and adenocarcinomas of the upper gastrointestinal tract (3.3%-12.5%). KLK7 positivity was linked to nodal metastasis (p = 0.0005), blood vessel infiltration (p = 0.0037), and lymph vessel infiltration (p < 0.0001) in colorectal adenocarcinoma, nodal metastasis in hepatocellular carcinoma (p = 0.0382), advanced pathological tumor stage in papillary thyroid cancer (p = 0.0132), and low grade of malignancy in a cohort of 719 squamous cell carcinomas from 11 different sites of origin (p < 0.0001). CONCLUSIONS: These data provide a comprehensive overview on KLK7 expression in normal and neoplastic human tissues. The prognostic relevance of KLK7 expression and the possible role of KLK7 as a drug target need to be further investigated.

Combining molecular dynamics simulations and scoring method to computationally model ubiquitylated linker histones in chromatosomes.

The chromatin in eukaryotic cells plays a fundamental role in all processes during a cell's life cycle. This nucleoprotein is normally tightly packed but needs to be unpacked for expression and division. The linker histones are critical for such packaging processes and while most experimental and simulation works recognize their crucial importance, the focus is nearly always set on the nucleosome as the basic chromatin building block. Linker histones can undergo several modifications, but only few studies on their ubiquitylation have been conducted. Mono-ubiquitylated linker histones (HUb), while poorly understood, are expected to influence DNA compaction. The size of ubiquitin and the globular domain of the linker histone are comparable and one would expect an increased disorder upon ubiquitylation of the linker histone. However, the formation of higher order chromatin is not hindered and ubiquitylation of the linker histone may even promote gene expression. Structural data on chromatosomes is rare and HUb has never been modeled in a chromatosome so far. Descriptions of the chromatin complex with HUb would greatly benefit from computational structural data. In this study we generate molecular dynamics simulation data for six differently linked HUb variants with the help of a sampling scheme tailored to drive the exploration of phase space. We identify conformational sub-states of the six HUb variants using the sketch-map algorithm for dimensionality reduction and iterative HDBSCAN for clustering on the excessively sampled, shallow free energy landscapes. We present a highly efficient geometric scoring method to identify sub-states of HUb that fit into the nucleosome. We predict HUb conformations inside a nucleosome using on-dyad and off-dyad chromatosome structures as reference and show that unbiased simulations of HUb produce significantly more fitting than non-fitting HUb conformations. A tetranucleosome array is used to show that ubiquitylation can even occur in chromatin without too much steric clashes.

Automated Ki-67 labeling index assessment in prostate cancer using artificial intelligence and multiplex fluorescence immunohistochemistry.

The Ki-67 labeling index (Ki-67 LI) is a strong prognostic marker in prostate cancer, although its analysis requires cumbersome manual quantification of Ki-67 immunostaining in 200-500 tumor cells. To enable automated Ki-67 LI assessment in routine clinical practice, a framework for automated Ki-67 LI quantification, which comprises three different artificial intelligence analysis steps and an algorithm for cell-distance analysis of multiplex fluorescence immunohistochemistry (mfIHC) staining, was developed and validated in a cohort of 12,475 prostate cancers. The prognostic impact of the Ki-67 LI was tested on a tissue microarray (TMA) containing one 0.6 mm sample per patient. A 'heterogeneity TMA' containing three to six samples from different tumor areas in each patient was used to model Ki-67 analysis of multiple different biopsies, and 30 prostate biopsies were analyzed to compare a 'classical' bright field-based Ki-67 analysis with the mfIHC-based framework. The Ki-67 LI provided strong and independent prognostic information in 11,845 analyzed prostate cancers (p < 0.001 each), and excellent agreement was found between the framework for automated Ki-67 LI assessment and the manual quantification in prostate biopsies from routine clinical practice (intraclass correlation coefficient: 0.94 [95% confidence interval: 0.87-0.97]). The analysis of the heterogeneity TMA revealed that the Ki-67 LI of the sample with the highest Gleason score (area under the curve [AUC]: 0.68) was as prognostic as the mean Ki-67 LI of all six foci (AUC: 0.71 [p = 0.24]). The combined analysis of the Ki-67 LI and Gleason score obtained on identical tissue spots showed that the Ki-67 LI added significant additional prognostic information in case of classical International Society of Urological Pathology grades (AUC: 0.82 [p = 0.002]) and quantitative Gleason score (AUC: 0.83 [p = 0.018]). The Ki-67 LI is a powerful prognostic parameter in prostate cancer that is now applicable in routine clinical practice. In the case of multiple cancer-positive biopsies, the sole automated analysis of the worst biopsy was sufficient. © 2023 The Authors. The Journal of Pathology published by John Wiley & Sons Ltd on behalf of The Pathological Society of Great Britain and Ireland.

PD-L1 expression in tumor and inflammatory cells is associated with favorable tumor features and favorable prognosis in muscle-invasive urothelial carcinoma of the bladder not treated by immune checkpoint inhibitors.

BACKGROUND: A high level of PD-L1 expression is the most relevant predictive parameter for response to immune checkpoint inhibitor (CPI) therapy in urinary bladder cancer. Existing data on the relationship between PD-L1 expression and the natural course of disease are controversial and sparse. METHODS: To expand our understanding of the relationship between PD-L1 expression and parameters of cancer aggressiveness, PD-L1 was analyzed on tissue microarrays containing 2710 urothelial bladder carcinomas including 512 patients with follow-up data who underwent radical cystectomy and follow-up therapies in the pre-immune checkpoint inhibitor therapy era. RESULTS: Tumor cell positivity in ≥10% of cells were seen in 513 (20%) and an immune cell positivity occurred in 872 (34%) of 2566 interpretable cancers. PD-L1 positivity in tumor cells increased from pTaG2 low grade (0.9% positive) to pTaG3 high grade (4.1%; p = 0.0255) and was even higher in muscle-invasive (pT2-4) carcinomas (29.3%; p < 0.0001). However, within pT2-4 carcinomas, PD-L1 positivity was linked to low pT stage (p = 0.0028), pN0 (p < 0.0001), L0 status (p = 0.0005), and a better prognosis within 512 patients with cystectomy who never received CPIs (p = 0.0073 for tumor cells and p = 0.0086 for inflammatory cells). PD-L1 staining in inflammatory cells was significantly linked to PD-L1 staining in tumor cells (p < 0.0001) and both were linked to a positive p53 immunostaining (p < 0.0001). CONCLUSION: It cannot be fully excluded that the strong statistical link between PD-L1 status and favorable histological tumor features as well as better prognosis could influence the outcome of studies evaluating CPIs in muscle-invasive urothelial carcinoma.

[Common and New Regional Anaesthesia Techniques Under Review - From Head to Abdomen]. / Alte und neue Regionalanästhesieverfahren unter Review ­ Kopf bis Bauch.

By implementation of sonography regional anesthesia became more relevant in the daily practice of anesthesia and pain therapy. Due to visualized needle guidance ultrasound supports more safety during needle placement. Thereby new truncal blocks got enabled. Next to the blocking of specific nerve structures, plane blocks got established which can also be described as interfascial compartment blocks. The present review illustrates published and established blocks in daily practice concerning indications and the procedural issues. Moreover, the authors explain potential risks, complications and dosing of local anesthetics.

Cell-Permeable Nicotinamide Adenine Dinucleotides for Exploration of Cellular Protein ADP-Ribosylation.

Posttranslational modifications (PTMs) greatly enhance the functional diversity of proteins, surpassing the number of gene-encoded variations. One intriguing PTM is ADP-ribosylation, which utilizes nicotinamide adenine dinucleotide (NAD+) as a substrate and is essential in cell signaling pathways regulating cellular responses. Here, we report the first cell-permeable NAD+ analogs and demonstrate their utility for investigating cellular ADP-ribosylation. Using a desthiobiotin-labelled analog for affinity enrichment of proteins that are ADP-ribosylated in living cells under oxidative stress, we identified protein targets associated with host-virus interactions, DNA damage and repair, protein biosynthesis, and ribosome biogenesis. Most of these targets have been noted in various literature sources, highlighting the potential of our probes for cellular ADP-ribosylome studies.

Structures of a DNA Polymerase Caught while Incorporating Responsive Dual-Functional Nucleotide Probes.

Functionalizing nucleic acids using DNA polymerases is essential in biophysical and biotechnology applications. This study focuses on understanding how DNA polymerases recognize and incorporate nucleotides with diverse chemical modifications, aiming to develop advanced nucleotide probes. We present the crystal structures of ternary complexes of Thermus aquaticus DNA polymerase (KlenTaq) with C5-heterocycle-modified environment-sensitive 2'-deoxyuridine-5'-triphosphate (dUTP) probes. These nucleotides include SedUTP, BFdUTP and FBFdUTP, which bear selenophene, benzofuran and fluorobenzofuran, respectively, at the C5 position of uracil, and exhibit high conformational sensitivity. SedUTP and FBFdUTP serve as dual-app probes, combining a fluorophore with X-ray anomalous scattering Se or 19F NMR labels. Our study reveals that the size of the heterocycle influences how DNA polymerase families A and B incorporate these modified nucleotides during single nucleotide incorporation and primer extension reactions. Remarkably, FBFdUTP's responsiveness enabled real-time monitoring of the binary complex formation and polymerase activity through fluorescence and 19F NMR. Comparative analysis of incorporation profiles, fluorescence, 19F NMR data, and crystal structures of ternary complexes highlights the enzyme's plasticity. Key insights are provided into the role of gatekeeper amino acids (Arg660 and Arg587) in accommodating and processing these modified substrates, offering a structural basis for next-generation nucleotide probe development.

A DNA Polymerase Variant Senses the Epigenetic Marker 5-Methylcytosine by Increased Misincorporation.

Dysregulation of DNA methylation is associated with human disease, particularly cancer, and the assessment of aberrant methylation patterns holds great promise for clinical diagnostics. However, DNA polymerases do not effectively discriminate between processing 5-methylcytosine (5 mC) and unmethylated cytosine, resulting in the silencing of methylation information during amplification or sequencing. As a result, current detection methods require multi-step DNA conversion treatments or careful analysis of sequencing data to decipher individual 5 mC bases. To overcome these challenges, we propose a novel DNA polymerase-mediated 5 mC detection approach. Here, we describe the engineering of a thermostable DNA polymerase variant derived from Thermus aquaticus with altered fidelity towards 5 mC. Using a screening-based evolutionary approach, we have identified a DNA polymerase that exhibits increased misincorporation towards 5 mC during DNA synthesis. This DNA polymerase generates mutation signatures at methylated CpG sites, allowing direct detection of 5 mC by reading an increased error rate after sequencing without prior treatment of the sample DNA.

Reverse Transcriptases: From Discovery and Applications to Xenobiology.

Reverse transcriptases are DNA polymerases that can use RNA as a template for DNA synthesis. They thus catalyze the reverse of transcription. Although discovered in 1970, reverse transcriptases are still of great interest and are constantly being further developed for numerous modern research approaches. They are frequently used in biotechnological and molecular diagnostic applications. In this review, we describe the discovery of these fascinating enzymes and summarize research results and applications ranging from molecular cloning, direct virus detection, and modern sequencing methods to xenobiology.

Cytokeratin 20 expression is linked to stage progression and to poor prognosis in advanced (pT4) urothelial carcinoma of the bladder.

Cytokeratin 20 (CK20) expression is limited to umbrella cells in the normal urothelium. Since CK20 is often upregulated in neoplastic urothelial cells including dysplasia and carcinoma in situ, immunohistochemical CK20 analysis is often used for the assessment of bladder biopsies. CK20 expression is a feature of luminal bladder cancer subtype, but its prognostic relevance is disputed. In this study, we investigated CK20 on >2700 urothelial bladder carcinomas in a tissue microarray format by immunohistochemistry. Cytoplasmic and membranous CK20 staining was seen in 1319 (51.8%) cancers. The fraction of CK20 positive and especially strongly positive cases increased from pTaG2 low grade (44.5% strongly positive) and pTaG2 high grade (57.7%) to pTaG3 high grade (62.3%; p = 0.0006) but was lower in muscle-invasive (pT2-4) carcinomas (51.1% in all pTa vs. 29.6% in pT2-4; p < 0.0001). Within pT2-4 carcinomas, CK20 positivity was linked to nodal metastasis and lymphatic vessel invasion (p < 0.0001 each) and to venous invasion (p = 0.0177). CK20 staining was unrelated to overall patient survival if all 605 pT2-4 carcinomas were jointly analyzed but subgroup analyses revealed a significant association of CK20 positivity with favorable prognosis in 129 pT4 carcinomas (p = 0.0005). CK20 positivity was strongly linked to the expression of GATA3 (p < 0.0001), another feature of luminal bladder cancer. The combined analysis of both parameters showed best prognosis for luminal A (CK20+/GATA3+, CK20+/GATA3-) and worst outcome for luminal B (CK20-/GATA3+) and basal/squamous (CK20-/GATA3-) in pT4 urothelial carcinomas (p = 0.0005). In summary, the results of our study demonstrate a complex role of CK20 expression in urothelial neoplasms including neoexpression in pTa tumors, a subsequent loss of CK20 expression in a subset of tumors progressing to muscle-invasion, and a stage dependent prognostic role in muscle-invasive cancers.

GATA3 Expression in Human Tumors: A Tissue Microarray Study on 16,557 Tumors.

INTRODUCTION: GATA3 is a transcription factor involved in epithelial cell differentiation. GATA3 immunostaining is used as a diagnostic marker for breast and urothelial cancer but can also occur in other neoplasms. METHODS: To evaluate GATA3 in normal and tumor tissues, a tissue microarray containing 16,557 samples from 131 different tumor types and subtypes and 608 samples of 76 different normal tissue types was analyzed by immunohistochemistry. RESULTS: GATA3 positivity was found in 69 different tumor types including 23 types (18%) with at least one strongly positive tumor. Highest positivity rates occurred in noninvasive papillary urothelial carcinoma (92-99%), lobular carcinoma (98%), carcinoma of no special type of the breast (92%), basal cell carcinoma of the skin (97%), invasive urothelial carcinoma (73%), T-cell lymphoma (23%), adenocarcinoma of the salivary gland (16%), squamous cell carcinoma of the skin (16%), and colorectal neuroendocrine carcinoma (12%). In breast cancer, low GATA3 staining was linked to high pT stage (p = 0.03), high BRE grade (p < 0.0001), HER2 overexpression (p = 0.0085), estrogen and progesterone receptor negativity (p < 0.0001 each), and reduced survival (p = 0.03). CONCLUSION: Our data demonstrate that GATA3 positivity can occur in various tumor entities. Low levels of GATA3 reflect cancer progression and poor patient prognosis in breast cancer.

Altered p53/p16 expression is linked to urothelial carcinoma progression but largely unrelated to prognosis in muscle-invasive tumors.

BACKGROUND: Most inactivating p53 mutations result in a nuclear p53 accumulation - detectable by immunohistochemistry (IHC). p53 alterations leading to a complete lack of p53 protein and absence of immunostaining do also occur - not easily detectable by IHC. p16 is upregulated in p53 inactivated cells. We hypothesized that a positive p16 IHC may help to distinguish p53 inactivation in IHC negative cases. MATERIAL AND METHODS: We investigated p53 and p16 immunostaining on 2710 urothelial bladder carcinomas in a tissue microarray format to understand their impact in relation to clinicopathological parameters of disease progression and patient outcome. RESULTS: p16 immunostaining was absent in normal urothelium but occurred in 63.5% (30.4% strong) of cancers. p16 strongly positive cases increased from pTaG2 low-grade (9.6%) to pTaG3 high-grade tumors (46.5%, p < .0001) but decreased from pTaG3 to pT4 (33.3%; p = .0030). Among pT2-4 carcinomas, p16 positivity was linked to high-grade (p = .0005) but unrelated to overall survival. p53 staining was negative in 8.4%, very weak in 15.4%, weak in 55.3%, strong in 4.7%, and very strong in 16.2% cancers. p53 negative (potentially p53 null phenotype), strong, and very strong p53 positivity increased from pTaG2 low-grade to pTaG3 high-grade tumors (p < .0001) and from pTaG3 to pT2-4 cancers (p = .0007). p53 staining was largely unrelated to histopathological parameters or patient prognosis among pT2-4 carcinomas, except of p53 strong/very strong immunostaining. p16 expression predominated in tumors with very strong, strong, and negative p53 staining and the combination of p53 negative/p16 strongly positive cancers was linked to features of tumor aggressiveness. CONCLUSION: Aberrant p53 and p16 immunostaining increases during grade and stage progression although p53 negative and p16 positive immunostaining lack prognostic significance in pT2-4 carcinomas. Potential diagnostic features are that high level p16 expression is limited to neoplastic urothelium and p53 null phenotype to aggressive cancers (grade 3 and invasive).

Chemical proteomics reveals interactors of the alarmone diadenosine triphosphate in the cancer cell line H1299.

Intracellular dinucleoside polyphosphates (Npn Ns) have been known for decades but the functional role remains enigmatic. Diadenosine triphosphate (Ap3 A) is one of the most prominent examples, and its intercellular concentration was shown to increase upon cellular stress. By employment of previously reported Ap3 A-based photoaffinity-labeling probes (PALPs) in chemical proteomics, we investigated the Ap3 A interactome in the human lung carcinoma cell line H1299. The cell line is deficient of the fragile histidine triade (Fhit) protein, a hydrolase of Ap3 A and tumor suppressor. Overall, the number of identified potential interaction partners was significantly lower than in the previously investigated HEK293T cell line. Gene ontology term analysis revealed that the identified proteins participate in similar pathways as for HEK293T, but the percentage of proteins involved in RNA-related processes is higher for H1299. The obtained results highlight similarities and differences of the Ap3 A interaction network in different cell lines and give further indications regarding the importance of the presence of Fhit.

Pattern of MUC6 expression across 119 different tumor types: A tissue microarray study on 15 412 tumors.

Mucin 6 (MUC6) is a secreted gel-forming mucin covering the surfaces of gastrointestinal and other tissues. Published work demonstrates that MUC6 can also be expressed in several cancer types and can aid in the distinction of different tumor entities. To systematically analyze MUC6 expression in normal and cancerous tissues, a tissue microarray containing 15 412 samples from 119 different tumor types and subtypes as well as 608 samples of 76 different normal tissue types was analyzed by immunohistochemistry. At least a weak MUC6 positivity was seen in 50 of 119 (42%) tumor entities. Thirty-three tumor entities included tumors with strong positivity. MUC6 immunostaining was most frequent in mucinous carcinomas of the breast (44%), adenocarcinomas of the stomach (30%-40%) and esophagus (35%), and neuroendocrine carcinomas of the colon. Strong MUC6 staining was linked to advanced pT stage (p = 0.0464), defective mismatch repair status and right-sided tumor location (p < 0.0001 each) in colorectal cancer, as well as to high tumor grade (p = 0.0291), nodal metastasis (p = 0.0485), erb-b2 receptor tyrosine kinase 2 positivity (p < 0.0001) and negative estrogen receptor (p = 0.0332)/progesterone receptor (p = 0.0257) status in breast carcinomas of no special type. The broad range of tumor types with MUC6 expression limits the utility of MUC6 immunohistochemistry for the distinction of different tumor types.