Effects of Lipidation on a Proline-Rich Antibacterial Peptide.

The emergence of multidrug-resistant bacteria is a worldwide health problem. Antimicrobial peptides have been recognized as potential alternatives to conventional antibiotics, but still require optimization. The proline-rich antimicrobial peptide Bac7(1-16) is active against only a limited number of Gram-negative bacteria. It kills bacteria by inhibiting protein synthesis after its internalization, which is mainly supported by the bacterial transporter SbmA. In this study, we tested two different lipidated forms of Bac7(1-16) with the aim of extending its activity against those bacterial species that lack SbmA. We linked a C12-alkyl chain or an ultrashort cationic lipopeptide Lp-I to the C-terminus of Bac7(1-16). Both the lipidated Bac-C12 and Bac-Lp-I forms acquired activity at low micromolar MIC values against several Gram-positive and Gram-negative bacteria. Moreover, unlike Bac7(1-16), Bac-C12, and Bac-Lp-I did not select resistant mutants in E. coli after 14 times of exposure to sub-MIC concentrations of the respective peptide. We demonstrated that the extended spectrum of activity and absence of de novo resistance are likely related to the acquired capability of the peptides to permeabilize cell membranes. These results indicate that C-terminal lipidation of a short proline-rich peptide profoundly alters its function and mode of action and provides useful insights into the design of novel broad-spectrum antibacterial agents.

Design, antimicrobial activity and mechanism of action of Arg-rich ultra-short cationic lipopeptides.

The increasing emergence of multidrug-resistant microorganisms represents one of the greatest challenges in the clinical management of infectious diseases, and requires the development of novel antimicrobial agents. To this aim, we de novo designed a library of Arg-rich ultra-short cationic antimicrobial lipopeptides (USCLs), based on the Arg-X-Trp-Arg-NH2 peptide moiety conjugated with a fatty acid, and investigated their antibacterial potential. USCLs exhibited an excellent antimicrobial activity against clinically pathogenic microorganisms, in particular Gram-positive bacteria, including multidrug resistant strains, with MIC values ranging between 1.56 and 6.25 µg/mL. The capability of the two most active molecules, Lau-RIWR-NH2 and Lau-RRIWRR-NH2, to interact with the bacterial membranes has been predicted by molecular dynamics and verified on liposomes by surface plasmon resonance. Both compounds inhibited the growth of S. aureus even at sub MIC concentrations and induced cell membranes permeabilization by producing visible cell surface alterations leading to a significant decrease in bacterial viability. Interestingly, no cytotoxic effects were evidenced for these lipopeptides up to 50-100 µg/mL in hemolysis assay, in human epidermal model and HaCaT cells, thus highlighting a good cell selectivity. These results, together with the simple composition of USCLs, make them promising lead compounds as new antimicrobials.

A single nucleotide polymorphism in EZH2 predicts overall survival rate in patients with cholangiocarcinoma.

Cholangiocarcinoma (CCA) is a deadly disease arising from the malignant transformation of cholangiocytes. Enhancer of zeste homolog 2 (EZH2) is overexpressed in poorly differentiated CCA. Functional single nucleotide polymorphisms (SNPs) in this gene may affect the role of EZH2 in cholangiocarcinogenesis and chemoresistance. The aim of the current study was to evaluate the correlation between EZH2 SNPs and clinical outcome. Using PROMO3.0, GeneCard and MicroSNiper, 4 EZH2 SNPs with functional relevance in CCA were selected in silico. These SNPs were studied in genomic DNA extracted from the blood samples of 75 patients with advanced CCA, who were treated with epirubicin-cisplatin-xeloda (ECX regimen). SNP genotyping was performed with specific PCR assays. The rs887569 TT genotype was correlated with a significantly longer overall survival (OS; TT vs. CT-CC, P=0.026). Moreover, the TT genotype revealed a trend toward a significant association with a reduced risk of mortality (HR, 0.59; 95% CI, 0.33-1.05; P=0.075), by multivariate analysis. These results support future studies on the role of rs887569 EZH2 SNP as a possible predictive marker of OS in advanced CCA patients.

Broad-spectrum activity of a novel antibiotic peptide against multidrug-resistant veterinary isolates.

The emergence of multidrug resistant (MDR) and extensively drug resistant (XDR) bacteria has become a medical and veterinary problem. Antimicrobial peptides (AMPs) show potential to overcome antibiotic resistance and could be used therapeutically. A novel AMP (AMP2041) was developed in silico and its microbiocidal activity against MDR clinical strains isolated from cattle (n=6), dogs (n=8), and pigs (n=20) was evaluated. AMP2041 showed strong antimicrobial activity against all Gram-positive and Gram-negative MDR clinical strains tested. Within 20 min of incubation, there was complete killing of Pseudomonas aeruginosa ATCC 27953 and a 90% reduction of colony count for Escherichia coli ATCC 25922. For Staphylococcus aureus ATCC 25923, a 90% reduction of colony count was observed within 120 min of incubation.

The BH3-mimetic ABT-737 targets the apoptotic machinery in cholangiocarcinoma cell lines resulting in synergistic interactions with zoledronic acid.

PURPOSE: In TFK-1 and EGI-1 cholangiocarcinoma cell lines, zoledronic acid (ZOL) determines an S-phase block without apoptosis. Here, we investigated the occurrence of apoptosis stigmata when ZOL is associated to the BH3-mimetic ABT-737. METHODS: In EGI-1 and TFK-1 cholangiocarcinoma cell lines untreated or treated with ABT-737 alone or in combination with ZOL, the pro-survival protein's pattern (BCL-2, BCL-XL, MCL-1, HSP72, HSP27) was investigated by biochemical criteria along with the occurrence of mitochondrial damage evaluated by cytofluorimetric analysis using a cationic dye. RESULTS: ABT-737 induced growth inhibition and significantly affected the colony-forming ability of both EGI-1 and TFK-1 cells. However, activated PARP-1 or/and caspase-3 cleavage (apoptosis markers) were detected only at the highest ABT-737 concentrations used. Combined treatment showed synergistic effect by converting the predominant cytostatic effect of ZOL into a cytotoxic one as shown by striking increment of mitochondrial harmed cells along with PARP-1 activation and caspase-3 cleavage. CONCLUSION: The lack of apoptosis following ZOL treatment in these cholangiocarcinoma cell lines appears to be multifactorial and could be ascribed to the large constitutive expression of pro-survival proteins. The efficacy of ZOL treatment requires a concomitant unleashing of apoptosis using a selective BH3-mimetic as ABT-737. The rational targeting of specific components of the apoptotic pathway may appear a useful approach to improve the treatment of refractory or relapsed cholangiocarcinoma. Combined treatment could be further explored in in vivo tumor model of cholangiocarcinoma.

Zoledronic acid determines S-phase arrest but fails to induce apoptosis in cholangiocarcinoma cells.

Cholangiocarcinoma is the second most common primary hepatic neoplasia and the only curative therapy is surgical resection or liver transplantation. Biphosphonates (BPs) are an emerging class of drugs widely used to treat bone diseases and also appear to possess direct antitumor activity. In two human cholangiocarcinoma cell lines (TFK-1 and EGI-1) we investigated, for the first time, the activity of zoledronic acid by determining proliferation, cell cycle analysis and apoptosis. The results obtained indicate that zoledronic acid induces cell-narrowing and growth inhibition, both reversed by 25 microM GGOH, and significantly affects the colony-forming ability of these cells. The inhibition by zoledronic acid of Rap1A prenylation was reversed in cell co-treated with GGOH. At 10-50 microM zoledronic acid exerted an S-phase cell cycle arrest which was confirmed by changes in the level of cyclins and of regulators p27(KIP1) and pRb. Interestingly, the expression level of cyclin A (putative S-phase marker) shows a dose-dependent increment in contrast to the decrement of cyclin D1 (putative G1 phase marker). However, neither hypodiploid cells nor cleaved PARP or caspase-3 was detected. The lack of TP53 or loss of its function, the large constitutive expressions of anti-apoptotic proteins Bcl-xL and HSP27 together with the low level of the pro-apoptotic Bax are the likely factors which protect cells from apoptosis. In conclusion, our study indicates that zoledronic acid induces S-phase arrest and cell-narrowing, both reversed by GGOH and, by changing the delicate balance between pro- and anti-apoptotic proteins, allows survival of cholangiocarcinoma cells.

Physicochemical and cell adhesion properties of chitosan films prepared from sugar and phosphate-containing solutions.

This work was aimed at investigating a series of chitosan films obtained from chitosan, chitosan-phosphate, chitosan-phosphate-D-(+)raffinose or chitosan-phosphate-D-(+)sucrose solutions to preliminarily select a suitable biomaterial for developing a cell substrate for tissue engineering. The prepared films were characterized in terms of physicochemical properties (FT-IR, XRD, optical microscopy, wettability, water absorption, and tensile stress) and effects on proliferation of different types of human cells (endothelial, HUVEC; fibroblast, WI-38). The obtained results indicated that the presence of sucrose or raffinose at high concentration along with phosphate salts in the chitosan film-forming solution affords smooth, amorphous and highly hydrophilic materials in the form of soft and elastic film with optimal cytocompatibility. Owing to improved physicochemical and mechanical properties as well as affinity for differentiated human cells, these novel chitosan films appear as promising candidate biomaterials for tissue regeneration and repair. The major finding is the possibility to improve the biocompatibility of chitosan films by simply modifying their solid state characteristics.

Low-level caloric restriction rescues proteasome activity and Hsc70 level in liver of aged rats.

Proteasome activity is known to decrease with aging in ad libitum (AL) fed rats. Severe caloric restriction (CR) significantly extends the maximum life-span of rats, and counteracts the age-associated decrease in liver proteasome activities. Since few investigations have explored whether lower CR diets might positively counteract the age associated decrease in proteasome activity, we then investigated the effects of a mild CR regimen on animal life-span, proteasome content and function. In addition, we addressed the question whether both CR regimens might also affect the expression of Hsc70 protein, a constitutive chaperone reported to share a role in the function of proteasome complex and in the repair of proteotoxic damage, and whose level decreased during aging. In contrast to severe CR, mild CR had a poor effect on life-span; however, it better counteracted the decrease of proteasome activities. Both regimens, however, maintain Hsc70 in liver of old rats at level comparable to that of young rats. Interestingly, the effects of aging and CRs on liver proteasome enzyme activities did not appear to be associated with parallel changes in the amount of proteasome proteins suggesting that the quality (molecular activity of the enzymes) rather than the quantity are likely to be modified with age. In conclusion, the results presented in this work show that a mild CR can have beneficial effects on liver function of aging rats because is adequate to counteract the decrease of proteasome function and Hsc70 chaperone level.

The expression of HSP27 is associated with poor clinical outcome in intrahepatic cholangiocarcinoma.

BACKGROUND: The heat shock proteins (HSPs) 27-kDa (HSP27) and 72-kDa (HSP72), are ubiquitous chaperone molecules inducible in cells exposed to different stress conditions. Increased level of HSPs are reported in several human cancers, and found to be associated with the resistance to some anticancer treatments and poor prognosis. However, there is no study of the relationship between HSPs expression and patient's prognosis in intrahepatic cholangiocarcinoma (IHCCA). In this exploratory retrospective study, we investigated the expressions of HSP27 and HSP72 as potential prognostic factors in IHCCA. METHODS: Thirty-one paraffin-embedded samples were analyzed by immunohistochemical methods using HSP27 and HSP72 monoclonal antibodies. Proliferation rate was assessed in the same specimens by using monoclonal antibody against phosphorylated histone H3 (pHH3). Fisher's exact test was used to assess the hypothesis of independence between categorical variables in 2 x 2 tables. The ANOVA procedure was used to evaluate the association between ordinal and categorical variables. Estimates of the survival probability were calculated using the Kaplan-Meier method, and the log rank test was employed to test the null hypothesis of equality in overall survival among groups. The hazard ratio associated with HSP27 and HSP72 expression was estimated by Cox hazard-proportional regression. RESULTS: The expression of HSP27 was related to mitotic index, tumor greatest dimension, capsular and vascular invasion while the expression of HSP72 was only related to the presence of necrosis and the lymphoid infiltration. Kaplan-Maier analysis suggested that the expression of HSP27 significantly worsened the patients' median overall survival (11 +/- 3.18 vs 55 +/- 4.1 months, P-value = 0.0003). Moreover HSP27-positive patients exhibited the worst mean survival (7.0 +/- 3.2 months) in the absence of concomitant HSP72 expression. CONCLUSION: The expression of HSP27, likely increasing cell proliferation, tumor mass, vascular and capsular invasion, might promote aggressive tumor behaviour in IHCCA and decrease patients' survival. Immunohistochemical detection of HSP27 on routine sections may provide a reliable prognostic marker for IHCCA able to influence the therapeutic strategies for this cancer.

The associated expression of Maspin and Bax proteins as a potential prognostic factor in intrahepatic cholangiocarcinoma.

BACKGROUND: Maspin, a member of the serpin family, is a suppressor of tumor growth, an inhibitor of angiogenesis and an inducer of apoptosis. Maspin induces apoptosis by increasing Bax, a member of the Bcl-2 family of apoptosis-regulating proteins. In this exploratory study, we investigated the associated expression of Maspin and Bax proteins as a potential prognostic factor in intrahepatic cholangiocarcinoma (IHCCA). METHODS: Twenty-two paraffin-embedded samples were analyzed by immunohistochemical methods using Maspin, Bax and CD34 antibodies. Maspin was scored semiquantitatively (HSCORE). Apoptosis was assessed using an antibody against cleaved caspase-3. RESULTS: The strong relationship observed between the expression of Maspin and Bax, indicates that Bax is likely to be the key effector of Maspin-mediated induction of apoptosis as indicated by the activation of cleaved caspase-3. We categorized Maspin HSCORE by calculating the optimal cutpoint. A Maspin HSCORE above the cutpoint was inversely related with tumor dimension, depth of tumor and vascular invasion. Uni/multivariate analysis suggests that a Maspin HSCORE below the cutpoint significantly worsens the patients' prognosis. Tumors with Maspin HSCORE below the cutpoint had a shorter survival (11+/-5 months) than did patients with Maspin HSCORE above the cutpoint (27+/-4 months), whereas Kaplan-Meier analysis and logrank test showed no significant difference in overall survival between the patients. CONCLUSION: The associated expression of Maspin and Bax might delay tumor progression in IHCCA. Maspin above the cutpoint might counteract tumor development by increasing cell apoptosis, and by decreasing tumor mass and cell invasion. The combined expression of Maspin and Bax appears to influence the susceptibility of tumor cholangiocytes to apoptosis and thus may be involved in delaying IHCCA progression.

The risk of developing metastatic disease in colorectal cancer is related to CD105-positive vessel count.

BACKGROUND AND OBJECTIVES: Angiogenesis is a complex multistep process that involves extracellular matrix remodeling, migration and proliferation of endothelial cells, and morphogenesis of microvessels. CD105 (endoglin), a co-receptor of the TGF-beta superfamily, was proposed as a marker of neovascularization in solid malignancies. The aim of this study was to evaluate retrospectively the effect of CD105-assessed angiogenesis on the risk of developing metastatic disease in colorectal cancer (CRC). METHODS: One hundred and twenty-five paraffin-embedded samples were analyzed by immunohistochemical methods using a CD105 monoclonal antibody. The median follow-up was 70.8 months. Survivals were calculated from actuarial estimates, and logistic regression predicted the risk of developing metastatic disease. RESULTS: The CD105-vessel count was strongly correlated with the occurrence of metastatic disease. The median CD105-positive vessels in patients with and without metastatic disease were 24.7 and 13.2 vessels/mm(2), respectively (P < 0.001). For each one microvessel increase in the vessels count per 400x field, there was a 1.42-fold increase in the risk of metastatic disease (P < 0.001). CONCLUSIONS: The assessment of tumor angiogenesis with anti-CD105 was not sufficient for its use as a surrogate end point for survival because of the amount of survival variability explained was only 8% in absence of metastatic disease. In contrast, multivariate logistic regression analysis revealed that CD105-vessels count can identify patients at high risk of metastatic disease.