MEK Is a Potential Indirect Target in Subtypes of Head and Neck Cancers

The poor prognosis of head-and-neck squamous cell carcinoma (HNSCC) is partly due to the lack of reliable prognostic and predictive markers. The Ras/Raf/MEK/ERK signaling pathway is often activated by overexpressed epidermal growth factor receptor (EGFR) and stimulates the progression of HNSCCs. Our research was performed on three human papillomavirus (HPV)-negative HNSCC-cell lines: Detroit 562, FaDu and SCC25. Changes in cell viability upon EGFR and/or MEK inhibitors were measured by the MTT method. The protein-expression and phosphorylation profiles of the EGFR-initiated signaling pathways were assessed using Western-blot analysis. The EGFR expression and pY1068-EGFR levels were also studied in the patient-derived HNSCC samples. We found significant differences between the sensitivity of the tumor-cell lines used. The SCC25 line was found to be the most sensitive to the MEK inhibitors, possibly due to the lack of feedback Akt activation through EGFR. By contrast, this feedback activation had an important role in the FaDu cells. The observed insensitivity of the Detroit 562 cells to the MEK inhibitors might have been caused by their PIK3CA mutation. Among HNSCC cell lines, EGFR-initiated signaling pathways are particularly versatile. An ERK/EGFR feedback loop can lead to Akt-pathway activation upon MEK inhibition, and it is related not only to increased amounts of EGFR but also to the elevation of pY1068-EGFR levels. The presence of this mechanism may justify the combined application of EGFR and MEK inhibitors.

Protein Kinase D3 (PKD3) Requires Hsp90 for Stability and Promotion of Prostate Cancer Cell Migration

Prostate cancer metastasis is a significant cause of mortality in men. PKD3 facilitates tumor growth and metastasis, however, its regulation is largely unclear. The Hsp90 chaperone stabilizes an array of signaling client proteins, thus is an enabler of the malignant phenotype. Here, using different prostate cancer cell lines, we report that Hsp90 ensures PKD3 conformational stability and function to promote cancer cell migration. We found that pharmacological inhibition of either PKDs or Hsp90 dose-dependently abrogated the migration of DU145 and PC3 metastatic prostate cancer cells. Hsp90 inhibition by ganetespib caused a dose-dependent depletion of PKD2, PKD3, and Akt, which are all involved in metastasis formation. Proximity ligation assay and immunoprecipitation experiments demonstrated a physical interaction between Hsp90 and PKD3. Inhibition of the chaperone-client interaction induced misfolding and proteasomal degradation of PKD3. PKD3 siRNA combined with ganetespib treatment demonstrated a specific involvement of PKD3 in DU145 and PC3 cell migration, which was entirely dependent on Hsp90. Finally, ectopic expression of PKD3 enhanced migration of non-metastatic LNCaP cells in an Hsp90-dependent manner. Altogether, our findings identify PKD3 as an Hsp90 client and uncover a potential mechanism of Hsp90 in prostate cancer metastasis. The molecular interaction revealed here may regulate other biological and pathological functions.

Composition and changes of blood microbiota in adult patients with community-acquired sepsis: A pilot study from bench to bedside

Background

Characteristics of the blood microbiota among adult patients with community-acquired sepsis are poorly understood. Our aim was to analyze the composition of blood microbiota in adult patients with community-acquired sepsis, and correlate changes with non-septic control patients.

Methods

A prospective observational study was carried out by including adult patients hospitalized for community-acquired sepsis at our center between January and November 2019, by random selection from a pool of eligible patients. Study inclusion was done on the day of sepsis diagnosis. Community acquisition was ascertained by a priori exclusion criteria; sepsis was defined according to the SEPSIS-3 definitions. Each included patient was matched with non-septic control patients by age and gender in a 1:1 fashion enrolled from the general population. Conventional culturing with BacT/ALERT system and 16S rRNA microbiota analysis were performed from blood samples taken in a same time from a patient. Abundance data was analyzed by the CosmosID HUB Microbiome software.

Results

Altogether, 13 hospitalized patients were included, 6/13 (46.2%) with sepsis and 7/13 (53.8%) with septic shock at diagnosis. The most prevalent etiopathogen isolated from blood cultures was Escherichia coli, patients mostly had intraabdominal septic source. At day 28, all-cause mortality was 15.4% (2/13). Compared to non-septic control patients, a relative scarcity of Faecalibacterium, Blautia, Coprococcus and Roseburia genera, with an abundance of Enhydrobacter, Pseudomonas and Micrococcus genera was observed among septic patients. Relative differences between septic vs. non-septic patients were more obvious at the phylum level, mainly driven by Firmicutes (25.7% vs. 63.1%; p<0.01) and Proteobacteria (36.9% vs. 16.6%; p<0.01). The alpha diversity, quantified by the Chao1 index showed statistically significant difference between septic vs. non-septic patients (126 ± 51 vs. 66 ± 26; p<0.01). The Bray-Curtis beta diversity, reported by principal coordinate analysis of total hit frequencies, revealed 2 potentially separate clusters among septic vs. non-septic patients.

Conclusion

In adult patients with community-acquired sepsis, specific changes in the composition and abundance of blood microbiota could be detected by 16S rRNA metagenome sequencing, compared to non-septic control patients. Traditional blood culture results only partially correlate with microbiota test results.

Human blood vessel microbiota in healthy adults based on common femoral arteries of brain-dead multi-organ donors

Discovery of human microbiota is fundamentally changing our perceptions of certain diseases and their treatments. However little is known about the human blood vessel microbiota, it may have important effects on vascular pathological lesions and vascular homograft failure. In our prospective survey study fourteen femoral arteries, harvested from donors in multi-organ donations, were examined using the V3-V4 region 16S rRNA sequencing method. The most abundant phyla in the human vascular microbiota were Proteobacteria, Firmicutes and Actinobacteria. At the genus level, the most abundant taxa were Staphylococcus, Corynebacterium, Pseudomonas, Bacillus, Acinetobacter and Propionibacterium. Of the bacterial taxa that have an indirect effect on the development of atherosclerosis, we found Porphyromonas gingivalis, Prevotella nigrescens and Enterobacteriaceae spp. with different abundances in our samples. Of the bacteria that are more common in the intestinal flora of healthy than of atherosclerosis patients, Roseburia and Ruminococcus occurred in the majority of samples. The human arterial wall has a unique microbiota that is significantly different in composition from that of other areas of the body. Our present study provides a basis for ensuing research that investigates the direct role of the microbiota in vascular wall abnormalities and the success of vascular allograft transplantations.

Novel Crizotinib-GnRH Conjugates Revealed the Significance of Lysosomal Trapping in GnRH-Based Drug Delivery Systems

Several promising anti-cancer drug–GnRH (gonadotropin-releasing hormone) conjugates have been developed in the last two decades, although none of them have been approved for clinical use yet. Crizotinib is an effective multi-target kinase inhibitor, approved against anaplastic lymphoma kinase (ALK)- or ROS proto-oncogene 1 (ROS-1)-positive non-small cell lung carcinoma (NSCLC); however, its application is accompanied by serious side effects. In order to deliver crizotinib selectively into the tumor cells, we synthesized novel crizotinib analogues and conjugated them to a [d-Lys⁶]–GnRH-I targeting peptide. Our most prominent crizotinib–GnRH conjugates, the amide-bond-containing [d-Lys⁶(crizotinib*)]–GnRH-I and the ester-bond-containing [d-Lys⁶(MJ55*)]–GnRH-I, were able to bind to GnRH-receptor (GnRHR) and exert a potent c-Met kinase inhibitory effect. The efficacy of compounds was tested on the MET-amplified and GnRHR-expressing EBC-1 NSCLC cells. In vitro pharmacological profiling led to the conclusion that that crizotinib–GnRH conjugates are transported directly into lysosomes, where the membrane permeability of crizotinib is diminished. As a consequence of GnRHR-mediated endocytosis, GnRH-conjugated crizotinib bypasses its molecular targets—the ATP-binding site of RTKs— and is sequestered in the lysosomes. These results explained the lower efficacy of crizotinib–GnRH conjugates in EBC-1 cells, and led to the conclusion that drug escape from the lysosomes is a major challenge in the development of clinically relevant anti-cancer drug–GnRH conjugates.

Auto- and alloantibodies against factor XIII: laboratory diagnosis and clinical consequences

Acquired FXIII deficiencies caused by autoantibodies against FXIII subunits represent rare but very severe bleeding diatheses. Alloantibodies in FXIII-deficient patients also cause life-threatening bleeding complications, but they develop extremely rarely. In this review we provide an overview of the diagnosis and classification of anti-FXIII antibodies and analyze 48 patients with autoimmune FXIII deficiency and four additional FXIII-deficient patients who developed anti-FXIII alloantibody. The patients were collected from peer-reviewed publications from which relevant data could be extracted. With the exception of two cases the antibodies were directed against FXIII-A. The difficulties in the diagnosis of FXIII deficiency in the presence of anti-FXIII antibodies are discussed and a scheme for the functional classification of the anti-FXIII antibodies is recommended. The three main categories are neutralizing and non-neutralizing antibodies and antibodies with combined effect. The methods being used for detecting and quantifying the inhibitory effect on FXIII activation and on the transglutaminase activity of activated FXIII are summarized and techniques for the classification of neutralizing anti-FXIII antibodies are outlined. The importance of clearance studies in these cases is emphasized. Binding assays, useful for the identification of non-neutralizing and combined type antibodies, were collected from the literature and their informative power is demonstrated by examples. The most frequently occurring bleeding symptoms in patients with anti-FXIII antibodies were soft tissue bleeding; intracranial bleedings also occurred, but less frequently than in inherited FXIII deficiency. Treatment of such patients is extremely challenging; the main aim should be eradication of the antibody.

Severe bleeding diatheses in an elderly patient with combined type autoantibody against factor XIII A subunit; novel approach to the diagnosis and classification of anti-factor XIII antibodies

INTRODUCTION

Acquired factor XIII (FXIII) deficiency due to autoantibody is a rare, severe bleeding diathesis. Its laboratory diagnosis and classification represents a difficult task.

AIM

Introduction of novel approaches into the diagnosis and characterization of anti-FXIII autoantibody and demonstration of their use in the diagnosis of a patient with autoimmune FXIII deficiency.

METHODS

Factor XIII activity, FXIII antigen levels and the titre of anti-FXIII-A antibody were monitored throughout the course of the disease. FXIII activity was measured by ammonia release assay; FXIII-A₂ B₂ complex, total and free FXIII-B concentrations were determined by ELISAs. The binding constant for the interaction of the autoantibody with recombinant FXIII-A₂ (rFXIII-A₂ ) and FXIII-A₂ B₂ was determined by surface plasmon resonance (SPR). The inhibitory capacity of IgG was expressed as the concentration exerting 50% inhibition of FXIII activation/activity (IC50). The truncation of FXIII-A by thrombin was monitored by western blotting. The inhibition of Ca²⁺ -induced FXIII activation and active FXIII (FXIIIa) were assessed by FXIII activity assay.

RESULTS

The antibody bound to rFXIII-A₂ and FXIII-A₂ B₂ with high affinity and accelerated the decay of supplemented FXIII concentrate. An IC50 value of 170.1 μg IgG·mL^-1 indicated effective FXIII neutralization. The main neutralizing effect of the autoantibody was the inhibition of FXIIIa. After 2 months, due to combined therapeutic modalities, the autoantibody disappeared and FXIII activity significantly elevated.

CONCLUSION

The anti-FXIII-A autoantibody exerted a combined effect including inhibition of FXIIIa and acceleration of FXIII decay in the plasma. IC50 and binding constant determinations added important information to the characterization of the autoantibody.

Neutralizing autoantibody against factor XIII A subunit resulted in severe bleeding diathesis with a fatal outcome - characterization of the antibody

Essentials Autoantibody against factor XIII (FXIII) is a rare but severe acquired hemorrhagic diathesis. In an elderly patient, anti-FXIII-A antibody led to severe bleedings with fatal outcome. The neutralizing autoantibody bound to FXIII with high affinity (Ka≈10(9) m(-1) ). The dominant effect of the autoantibody was the inhibition of activated FXIII.

SUMMARY

Autoantibodies may develop against the catalytic A subunit of factor XIII (FXIII-A) or the carrier B subunit (FXIII-B). Autoimmune FXIII-A deficiency was diagnosed in an elderly (75 years) patient with severe bleeding symptoms. The patient had 3% FXIII activity, and unmeasurable FXIII-A2 B2 and FXIII-A antigens in the plasma, whereas, in the platelet lysate, activity and FXIII-A antigen values were normal. As revealed by western blotting, FXIII antigen was present in the plasma, but the autoantibody interfered with the immunoassays. A mixing study indicated the presence of inhibitor with a titer of 63.2 Bethesda units (BU). The patient's IgG bound to FXIII-A2 B2 and to FXIII-A2 with equally high affinity (Ka in the range of 10(9) m(-1) ). It exerted a multiple inhibitory effect on FXIII activation/activity (IC50: 50 μg mL(-1) ). Immunosupressive therapy gradually decreased the autoantibody titer to 8.0 BU, but FXIII activity remained very low, and, owing to recurrent bleeding, the patient died.

Combined inhibition of AXL, Lyn and p130Cas kinases block migration of triple negative breast cancer cells

Blocking the migration of metastatic cancer cells is a major goal in the therapy of cancer. The receptor tyrosine kinase AXL is one of the main triggers for cancer cell migration in neoplasia of breast, colon, skin, thyroid and prostate. In our study we analyzed the effect of AXL inhibition on cell motility and viability in triple negative breast cancer cell lines overexpressing AXL. Thereby we reveal that the compound BMS777607, exhibiting the lowest IC50 values for inhibition of AXL kinase activity in the studied cell lines, attenuates cell motility to a lower extent than the kinase inhibitors MPCD84111 and SKI606. By analyzing the target kinases of MPCD84111 and SKI606 with kinase profiling assays we identified Lyn, a Src family kinase, as a target of both compounds. Knockdown of Lyn and the migration-related CRK-associated substrate (p130Cas), had a significant inhibitory effect on cell migration. Taken together, our findings highlight the importance of combinatorial or multikinase inhibition of non-receptor tyrosine kinases and AXL receptor tyrosine kinase in the therapy of triple negative breast cancer.

Discovery and Biological Evaluation of Novel Dual EGFR/c-Met Inhibitors

Activating mutations in the epidermal growth factor receptor (EGFR) have been identified in a subset of non-small cell lung cancer (NSCLC), which is one of the leading cancer types worldwide. Application of EGFR tyrosine kinase inhibitors leads to acquired resistance by secondary EGFR mutations or by amplification of the hepatocyte growth factor receptor (c-Met) gene. Although several EGFR and c-Met inhibitors have been reported, potent dual EGFR/c-Met inhibitors, which can overcome this latter resistance mechanism, have hitherto not been published and have not reached clinical trials. In the present study we have identified dual EGFR/c-Met inhibitors and designed novel N-[4-(quinolin-4-yloxy)-phenyl]-biarylsulfonamide derivatives, which inhibit the c-Met receptor and both the wild-type and the activating mutant EGFR kinases in nanomolar range. We have demonstrated by Western blot analysis that compound 10 inhibits EGFR and c-Met phosphorylation at cellular level and effectively inhibits viability of the NSCLC cell lines.

Molecular mechanism of the interaction between activated factor XIII and its glutamine donor peptide substrate

BACKGROUND

Activated factor XIII (FXIII), a dimer of truncated A-subunits (FXIII-A2*), is a transglutaminase that crosslinks primary amines to peptide-bound glutamine residues. Because in the few natural substrates of FXIII-A2* no consensus sequence could be identified around the reactive glutamine, studying the interaction between individual substrates and FXIII-A2* is of primary importance. Most of the alpha2-plasmin inhibitor (alpha2PI) molecules become truncated by a plasma protease, and the truncated isoform (N1-alpha2PI) is an important substrate of FXIII-A2*. The crosslinking of N1-alpha2PI to fibrin plays a major role in protecting fibrin from fibrinolysis.

METHODS

We studied the interaction of FXIII-A2* with its dodecapeptide glutamine donor substrate, N1-alpha2PI(1-12), the sequence of which corresponds to the N-terminal sequence of N1-alpha2PI. Kinetic parameters for N1-alpha2PI(1-12) and for its truncated or synthetic mutants were determined by a spectrophotometric assay. The interaction of N1-alpha2PI(1-12) with FXIII-A2* was investigated by proton nuclear magnetic resonance (NMR) and saturating transfer difference (STD) NMR.

RESULTS AND CONCLUSIONS

Kinetic experiments with peptides in which the Asn1 residue was either truncated or replaced by alanine and proton NMR analysis of the FXIII-A2*-N1-alpha2PI(1-12) complex demonstrated that Asn1 is essential for effective enzyme-substrate interaction. Experiments with C-terminally truncated peptides proved that amino acids 7-12 are essential for the interaction of N1-alpha2PI(1-12) with the enzyme, and suggested the existence of a secondary binding site on FXIII-A2*. Hydrophobic residues, particularly Leu10 and the C-terminal Lys12, seemed to be especially important in this respect, and direct interaction between hydrophobic C-terminal residues and FXIII-A2* was demonstrated by STD NMR.