Role of targeted therapy in the treatment of squamous cell head and neck cancer

Epidermal growth factor receptor (EGFR) is highly expressed in head and neck cancer (HNC). Since EGFR has a large extracellular ligand binding as well as an intracellular tyrosine kinase domain, anti-EGFR therapy may involve anti-ligand binding domain antibody- or tyrosine kinase inhibitor therapies. Phase II-III studies confirmed the efficacy of anti-EGFR antibody therapy in case of squamous cell HNC. In combination with irradiation, anti-EGFR antibody therapy improved survival of locally advanced HNC patients. In case of recurrent or metastatic HNC, anti-EGFR antibody therapy in combination with chemotherapy significantly increased remission rate without increasing toxicity. Although studies on EGFR kinase inhibitors in HNC are in early phase, preliminary data are encouraging.     

Chronic infections and genetic factors in the development of ischemic stroke

The aim of this study was to examine whether chronic infections and genetic factors of the host play roles in the pathophysiology of acute noncardioembolic ischemic stroke. Blood samples from 59 subjects with ischemic stroke and 52 control patients were investigated by nested PCR for the presence of C. pneumoniae DNA, HCMV DNA and enterovirus RNA, by ELISA for the levels of antibodies to C. pneumoniae, HCMV, HSV, HHV-6, EBV and the inflammatory chemokine IL-8, and by PCR for promoter polymorphism of the IL-8 and CD14 host genes. Associations of stroke with the HCMV IgG and HSV-1 IgA antibody levels were observed. No association of stroke was detected with the presence of C. pneumoniae, HCMV or enterovirus nucleic acids in the peripheral blood, C. pneumoniae IgM, IgG and IgA, the HSV IgG, the EBV IgG, or HHV-6 IgG antibody levels, the pathogen burden, the IL-8 or CD14 promoter polymorphisms, or with the serum levels of IL-8 in the overall study population. These results are consistent with the hypothesis that certain pathogens are involved in the development of ischemic stroke.     

DisCons: a novel tool to quantify and classify evolutionary conservation of intrinsic protein disorder

Background

Analyzing the amino acid sequence of an intrinsically disordered protein (IDP) in an evolutionary context can yield novel insights on the functional role of disordered regions and sequence element(s). However, in the case of many IDPs, the lack of evolutionary conservation of the primary sequence can hamper the study of functionality, because the conservation of their disorder profile and ensuing function(s) may not appear in a traditional analysis of the evolutionary history of the protein.

Results

Here we present DisCons (Disorder Conservation), a novel pipelined tool that combines the quantification of sequence- and disorder conservation to classify disordered residue positions. According to this scheme, the most interesting categories (for functional purposes) are constrained disordered residues and flexible disordered residues. The former residues show conservation of both the sequence and the property of disorder and are associated mainly with specific binding functionalities (e.g., short, linear motifs, SLiMs), whereas the latter class correspond to segments where disorder as a feature is important for function as opposed to the identity of the underlying sequence (e.g., entropic chains and linkers). DisCons therefore helps with elucidating the function(s) arising from the disordered state by analyzing individual proteins as well as large-scale proteomics datasets.

Conclusions

DisCons is an openly accessible sequence analysis tool that identifies and highlights structurally disordered segments of proteins where the conformational flexibility is conserved across homologs, and therefore potentially functional. The tool is freely available both as a web application and as stand-alone source code hosted at http://pedb.vib.be/discons.     

The clinical importance of methylenetetrahydrofolate reductase (MTHFR) C677T polymorphism in the 5-fluoropyrimidine-based therapy of metastatic colorectal tumours

The authors investigated the methylenetetrahydrofolate reductase (MTHFR) C677T polymorphism in 101 metastatic colorectal cancer patients treated with 5-fluoropyrimidine-based therapy and in 196 healthy individuals by PCR-RFLP method. There was no significant difference in genotype distribution of patients and healthy controls, and between subgroups investigated according to clinical parameters (age, gender, tumor location, grade and treatment type). However, after a 3-30 (median 18.5) months follow-up the survival of patients with T allele proved to be better than that of patients with wild type (CC) genotype (p=0.036). In case of CT and TT genotypes the survival of patients receiving only first line therapy was significantly shorter than that of patients receiving more lines of treatment (p=0.015). Determination of MTHFR C677T polymorphism has prognostic value in case of patients with metastatic colorectal cancer receiving 5-fluoropyrimidine-based therapy, and may help in designing the individual (group) tailored therapy.     

A Cilia Independent Role of Ift88/Polaris during Cell Migration

Ift88 is a central component of the intraflagellar transport (Ift) complex B, essential for the building of cilia and flagella from single cell organisms to mammals. Loss of Ift88 results in the absence of cilia and causes left-right asymmetry defects, disordered Hedgehog signaling, and polycystic kidney disease, all of which are explained by aberrant ciliary function. In addition, a number of extraciliary functions of Ift88 have been described that affect the cell-cycle, mitosis, and targeting of the T-cell receptor to the immunological synapse. Similarly, another essential ciliary molecule, the kinesin-2 subunit Kif3a, which transports Ift-B in the cilium, affects microtubule (MT) dynamics at the leading edge of migrating cells independently of cilia. We now show that loss of Ift88 impairs cell migration irrespective of cilia. Ift88 is required for the polarization of migrating MDCK cells, and Ift88 depleted cells have fewer MTs at the leading edge. Neither MT dynamics nor MT nucleation are dependent on Ift88. Our findings dissociate the function of Ift88 from Kif3a outside the cilium and suggest a novel extraciliary function for Ift88. Future studies need to address what unifying mechanism underlies the different extraciliary functions of Ift88.     

The effect of conjugation on antitumor activity of vindoline derivatives with octaarginine,a cell‐penetrating peptide

Some Vinca alkaloids (eg, vinblastine, vincristine) have been widely used as antitumor drugs for a long time. Unfortunately, vindoline, a main alkaloid component of Catharanthus roseus (L.) G. Don, itself, has no antitumor activity. In our novel research program, we have prepared and identified new vindoline derivatives with moderate cytostatic activity. Here, we describe the effect of conjugation of vindoline derivative with oligoarginine (tetra‐, hexa‐, or octapeptides) cell‐penetrating peptides on the cytostatic activity in vitro and in vivo. Br‐Vindoline‐(l )‐Trp‐OH attached to the N‐terminus of octaarginine was the most effective compound in vitro on HL‐60 cell line. Analysis of the in vitro activity of two isomer conjugates (Br‐vindoline‐(l )‐Trp‐Arg₈ and Br‐vindoline‐(d )‐Trp‐Arg₈ suggests the covalent attachment of the vindoline derivatives to octaarginine increased the antitumor activity significantly against P388 and C26 tumour cells in vitro. The cytostatic effect was dependent on the presence and configuration of Trp in the conjugate as well as on the cell line studied. The configuration of Trp notably influenced the activity on C26 and P388 cells: conjugate with (l )‐Trp was more active than conjugate with the (d )‐isomer. In contrast, conjugates had very similar effect on both the HL‐60 and MDA‐MB‐231 cells. In preliminary experiments, conjugate Br‐vindoline‐(l )‐Trp‐Arg₈ exhibited some inhibitory effect on the tumor growth in P388 mouse leukemia tumor‐bearing mice. Our results indicate that the conjugation of modified vindoline could result in an effective compound even with in vivo antitumor activity.     

Comparison of Killing Activity of Micafungin Against Six <Emphasis Type="Italic">Candida</Emphasis> Species Isolated from Peritoneal and Pleural Cavities in RPMI-1640, 10 and 30% Serum

Currently echinocandins are recommended in Candida peritonitis and pleuritis. We determined micafungin killing rates (k values) at therapeutic concentrations (0.25–2 mg/L) in RPMI-1640 with and without 10 and 30% serum mimicking in vivo conditions against six Candida species isolated from peritoneal and pleural fluid. In RPMI-1640, micafungin was fungicidal against C. glabrata, C. krusei and C. kefyr within 2.27?±?10.68, 2.69?±?10.29 and 3.10?±?4.41 h, respectively, while was fungistatic against C. albicans, C. tropicalis and C. parapsilosis. In 10% serum, ≥?0.25, ≥?0.5, ≥?0.5 and ≥?1 mg/L micafungin produced positive k values (killing) for all C. albicans, C. glabrata, C. kefyr and C. krusei, respectively. In 30% serum, 2 mg/L micafungin produced killing against all C. albicans, C. glabrata and C. kefyr isolates, but was ineffective against C. krusei, C. parapsilosis and 2 of 3 C. tropicalis. Micafungin exposure should be increased against non-albicans species to eradicate fungi from peritoneal and pleural cavities.     

The von Hippel-Lindau tumor suppressor protein controls ciliogenesis by orienting microtubule growth

Cilia are specialized organelles that play an important role in several biological processes, including mechanosensation, photoperception, and osmosignaling. Mutations in proteins localized to cilia have been implicated in a growing number of human diseases. In this study, we demonstrate that the von Hippel-Lindau (VHL) protein (pVHL) is a ciliary protein that controls ciliogenesis in kidney cells. Knockdown of pVHL impeded the formation of cilia in mouse inner medullary collecting duct 3 kidney cells, whereas the expression of pVHL in VHL-negative renal cancer cells rescued the ciliogenesis defect. Using green fluorescent protein-tagged end-binding protein 1 to label microtubule plus ends, we found that pVHL does not affect the microtubule growth rate but is needed to orient the growth of microtubules toward the cell periphery, a prerequisite for the formation of cilia. Furthermore, pVHL interacts with the Par3-Par6-atypical PKC complex, suggesting a mechanism for linking polarity pathways to microtubule capture and ciliogenesis.     

Arginase inhibition restores arteriolar endothelial function in Dahl rats with salt-induced hypertension

Vascular tissues express arginase that metabolizes L-arginine to L-ornithine and urea and thus reduces substrate availability for nitric oxide formation. Dahl salt-sensitive (Dahl-S) rats with salt-induced hypertension show endothelial dysfunction, including decreased vascular nitric oxide formation. This study tests the hypothesis that increased vascular arginase activity contributes to endothelial dysfunction in hypertensive Dahl-S rats. Male Dahl-S rats (5-6 wk) were placed on high (8%) or low (0.3%) NaCl diets for 4 wk. With respect to the low-salt group, mean arterial blood pressure was increased in the high-salt animals. Immunohistochemical stainings for arginase I and II were enhanced in arterioles isolated from high-salt Dahl-S rats. Experiments used isolated Krebs buffer-superfused first-order gracilis muscle arterioles with constant pressure (80 mmHg) and no luminal flow or constant midpoint but altered endpoint pressures to establish graded levels of luminal flow (0-50 microl/min). In high-salt arterioles, responses to an endothelium-dependent vasodilator acetylcholine (1 nmol/l to 3 micromol/l) and flow-induced dilation were decreased. Acute in vitro treatment with an inhibitor of arginase, 100 micromol/l (S)-(2-boronoethyl)-L-cystine, or the nitric oxide precursor, 1 mmol/l L-arginine, similarly enhanced acetylcholine and flow-induced maximal dilations and abolished the differences between high- and low-salt arterioles. These data show that arteriolar arginase expression is increased and that endothelium-dependent vasodilation is decreased in high-salt Dahl-S rats. Acute pretreatment with an arginase inhibitor or with L-arginine restores endothelium-dependent vasodilation and abolishes the differences between high- and low-salt groups. These results suggest that enhanced vascular arginase activity contributes to endothelial dysfunction in Dahl-S rats with salt-induced hypertension and identifies arginase as a potential therapeutic target to prevent endothelial dysfunction.