The role of tryptophan in protein fibrillogenesis: relevance of Trp7 and Trp14 to the amyloidogenic properties of myoglobin

In order to understand the role of tryptophan in the mechanisms of fibrils formation, the ability of a series of analogs of the residue 7-18 span of myoglobin to form amyloid-like fibrils was investigated. Alternatively one or both tryptophans were substituted with alanine and leucine, to determine the contribution of hydrophobicity and aromaticity. The scale of aggregation propensity of the peptides determined indicates that tryptophan is crucial for the amyloidogenic process. Since the rare tryptophan residue is generally engaged in structural roles in proteins, or when exposed serves as binding sites, we surmise that its exposure in the amyloidogenic fragments allows for intermolecular clustering with residues from other molecules leading to the formation of amyloid aggregates.     

Synthesis,Computational Studies and Assessment of in Vitro Activity of Squalene Derivatives as Carbonic Anhydrase Inhibitors

We report novel molecules incorporating the nontoxic squalene scaffold and different carbonic anhydrase inhibitors (CAIs). Potent inhibitory action, in the low-nanomolar range, was detected against isoforms hCA II for sulfonamide derivatives, which proved to be selective against this isoform over the tumor-associate hCA IX and XII isoforms. On the other hand, coumarin derivatives showed weak potency but high selectivity against the tumor-associated isoform CA IX. These compounds are interesting candidates for preclinical evaluation in glaucoma or various tumors in which the two enzymes are involved. In addition, an in silico study of inhibitor-bound hCA II revealed extensive interactions with the hydrophobic pocket of the active site and provided molecular insights into the binding properties of these new inhibitors.     

Sex and Depot Differences in Palmitoleic Acid Content of Human Blood and Fat

Palmitoleic acid has been classified as an insulin-sensitizing lipokine, but evidence for this from human studies has been inconsistent. We hypothesized that this is related to either the types of samples or conditions under which samples are collected. We measured plasma palmitoleic acid and total free fatty acids (FFA) using ultra-performance liquid chromatography in blood samples collected from 34 adults under a variety of conditions. We collected duplicate samples of adipose (n = 10), FFA (n = 9), and very low density lipoprotein triacylglycerol (VLDL-TAG) (n = 7) to measure the palmitoleic acid as a percentage of total fatty acids. We tested whether the percentage of palmitoleic acid was correlated with insulin resistance, as measured by homeostatic model of insulin resistance (HOMA-IR). Adipose stearoyl-coenzyme A desaturase 1 (SCD-1) protein was measured by capillary Western blotting. FFA-palmitoleic acid percentage increased as a function of total FFA and was greater (p < 0.005) in females than males. Adipose palmitoleic acid percentage was greater in females than males (p < 0.001), as was adipose SCD-1. Palmitoleic acid was greater in femoral fat than in abdominal fat in both females and males (p < 0.001), and correlated positively with HOMA-IR only in females. The test–retest reliability values for percentage palmitoleic acid were 7 ± 10% for adipose, 24 ± 26% for VLDL, and 53 ± 31% for FFA. Because FFA-palmitoleic acid percentage varies as a function of total FFA, investigators should re-evaluate how palmitoleic acid data is presented. The positive relationship between adipose palmitoleic acid and HOMA-IR in females suggests that it is not a potent insulin-sensitizing lipokine in humans.     

AXL Receptor in Breast Cancer: Molecular Involvement and Therapeutic Limitations

Breast cancer was one of the first malignancies to benefit from targeted therapy, i.e., treatments directed against specific markers. Inhibitors against HER2 are a significant example and they improved the life expectancy of a large cohort of patients. Research on new biomarkers, therefore, is always current and important. AXL, a member of the TYRO-3, AXL and MER (TAM) subfamily, is, today, considered a predictive and prognostic biomarker in many tumor contexts, primarily breast cancer. Its oncogenic implications make it an ideal target for the development of new pharmacological agents; moreover, its recent role as immune-modulator makes AXL particularly attractive to researchers involved in the study of interactions between cancer and the tumor microenvironment (TME). All these peculiarities characterize AXL as compared to other members of the TAM family. In this review, we will illustrate the biological role played by AXL in breast tumor cells, highlighting its molecular and biological features, its involvement in tumor progression and its implication as a target in ongoing clinical trials.     

Role of Extracellular Vesicles in Epithelial Ovarian Cancer: A Systematic Review

Extracellular vesicles (EVs) are a heterogeneous group of cell-derived submicron vesicles released under physiological or pathological conditions. EVs mediate the cellular crosstalk, thus contributing to defining the tumor microenvironment, including in epithelial ovarian cancer (EOC). The available literature investigating the role of EVs in EOC has been reviewed following PRISMA guidelines, focusing on the role of EVs in early disease diagnosis, metastatic spread, and the development of chemoresistance in EOC. Data were identified from searches of Medline, Current Contents, PubMed, and from references in relevant articles from 2010 to 1 April 2020. The research yielded 194 results. Of these, a total of 36 papers, 9 reviews, and 27 original types of research were retained and analyzed. The literature findings demonstrate that a panel of EV-derived circulating miRNAs may be useful for early diagnosis of EOC. Furthermore, it appears clear that EVs are involved in mediating two crucial processes for metastatic and chemoresistance development: the epithelial–mesenchymal transition, and tumor escape from the immune system response. Further studies, more focused on in vivo evidence, are urgently needed to clarify the role of EV assessment in the clinical management of EOC patients.     

Role of NEU3 Overexpression in the Prediction of Efficacy of EGFR-Targeted Therapies in Colon Cancer Cell Lines

The epidermal growth factor receptor (EGFR), through the MAP kinase and PI3K-Akt-mTOR axis, plays a pivotal role in colorectal cancer (CRC) pathogenesis. The membrane-associated NEU3 sialidase interacts with and desialylates EGFR by promoting its dimerization and downstream effectors’ activation. Among the targeted therapies against EGFR, the monoclonal antibody cetuximab is active only in a subgroup of patients not carrying mutations in the MAP kinase pathway. In order to better understand the EGFR-NEU3 interplay and the mechanisms of pharmacological resistance, we investigated the role of NEU3 deregulation in cetuximab-treated CRC cell lines transiently transfected with NEU3 using Western blot analysis. Our results indicate that NEU3 overexpression can enhance EGFR activation only if EGFR is overexpressed, indicating the existence of a threshold for NEU3-mediated EGFR activation. This enhancement mainly leads to the constitutive activation of the MAP kinase pathway. Consequently, we suggest that the evaluation of NEU3 expression cannot entirely substitute the evaluation of EGFR because EGFR-negative cases cannot be stimulated by NEU3. Furthermore, NEU3-mediated hyperactivation of EGFR is counterbalanced by the administration of cetuximab, hypothesizing that a combined treatment of NEU3- and EGFR-targeted therapies may represent a valid option for CRC patients, which must be investigated in the future.     

A Topical Formulation of Melatoninergic Compounds Exerts Strong Hypotensive and Neuroprotective Effects in a Rat Model of Hypertensive Glaucoma

Melatonin is of great importance for regulating several eye processes, including pressure homeostasis. Melatonin in combination with agomelatine has been recently reported to reduce intraocular pressure (IOP) with higher efficacy than each compound alone. Here, we used the methylcellulose (MCE) rat model of hypertensive glaucoma, an optic neuropathy characterized by the apoptotic death of retinal ganglion cells (RGCs), to evaluate the hypotensive and neuroprotective efficacy of an eye drop nanomicellar formulation containing melatonin/agomelatine. Eye tissue distribution of melatonin/agomelatine in healthy rats was evaluated by HPLC/MS/MS. In the MCE model, we assessed by tonometry the hypotensive efficacy of melatonin/agomelatine. Neuroprotection was revealed by electroretinography; by levels of inflammatory and apoptotic markers; and by RGC density. The effects of melatonin/agomelatine were compared with those of timolol (a beta blocker with prevalent hypotensive activity) or brimonidine (an alpha 2 adrenergic agonist with potential neuroprotective efficacy), two drugs commonly used to treat glaucoma. Both melatonin and agomelatine penetrate the posterior segment of the eye. In the MCE model, IOP elevation was drastically reduced by melatonin/agomelatine with higher efficacy than that of timolol or brimonidine. Concomitantly, gliosis-related inflammation and the Bax-associated apoptosis were partially prevented, thus leading to RGC survival and recovered retinal dysfunction. We suggest that topical melatoninergic compounds might be beneficial for ocular health.     

NMR structure of the (+)-CPI-indole/d(GACTAATTGAC)-d(GTCAATTAGTC) covalent complex

We report the NMR solution structure of (+)-CPI-indole (CPI, 1,2,8,8a-tetrahydrocyclopropa[c]pyrrolo[3,2-e]indol-4(5H)-one), an agent belonging to the CC-1065/duocarmycin family of antitumor compounds. This (+)-CPI-indole structure is covalently bound to d(G(1)ACTAATTGTC(11))-d(G(12)TCAATTAGTC(22)), a synthetic DNA duplex containing a high-affinity binding site. The three-dimensional structure has been determined by several cycles of restrained molecular dynamics calculations with a total of 563 NMR-derived constraints, both in vacuo and by using the generalized Born solvent continuum model. In-depth analysis of the structure of this ligand-DNA complex led to a detailed knowledge of the bound state conformation of the CPI-indole, the most simplified agent related to CC-1065 and duocarmycins, the parent members of a family of extremely potent antitumor compounds. Comparison of the CPI-indole bound conformation with those previously found for (+)-duocarmycin SA (DSA), its unnatural enantiomer (-)-DSA, and the demethoxylated analogue (+)-DSI in their DNA complexes provided additional evidence of the tight correlation between the catalytic effect exerted by DNA on the alkylation reaction and the extent of angular twist between the two planar heteroaromatic subunits of these agents. Additionally, comparison of the structural features of the DNA-bound state of a "naked" ligand, such as CPI-indole, with those of various other duocarmycin agents provided useful information for the interpretation of the observed effects on chemical reactivity of the different substitution patterns at the hemispheres of these types of complex.     

Co-Expression and Co-Localization of Cartilage Glycoproteins CHI3L1 and Lubricin in Osteoarthritic Cartilage: Morphological,Immunohistochemical and Gene Expression Profiles

Osteoarthritis is the most common human arthritis characterized by degeneration of articular cartilage. Several studies reported that levels of human cartilage glycoprotein chitinase 3-like-1 (CHI3L1) are known as a potential marker for the activation of chondrocytes and the progression of Osteoarthritis (OA), whereas lubricin appears to be chondroprotective. The aim of this study was to investigate the co-expression and co-localization of CHI3L1 and lubricin in normal and osteoarthritic rat articular cartilage to correlate their modified expression to a specific grade of OA. Samples of normal and osteoarthritic rat articular cartilage were analyzed by the Kellgren–Lawrence OA severity scores, the Kraus’ modified Mankin score and the Histopathology Osteoarthritis Research Society International (OARSI) system for histomorphometric evaluations, and through CHI3L1 and lubricin gene expression, immunohistochemistry and double immuno-staining analysis. The immunoexpression and the mRNA levels of lubricin increased in normal cartilage and decreased in OA cartilage (normal vs. OA, p < 0.01). By contrast, the immunoexpression and the mRNA levels of CHI3L1 increased in OA cartilage and decreased in normal cartilage (normal vs. OA, p < 0.01). Our findings are consistent with reports suggesting that these two glycoproteins are functionally associated with the development of OA and in particular with grade 2/3 of OA, suggesting that in the future they could be helpful to stage the severity and progression of the disease.     

La0.6Sr0.4Co0.2Fe0.8O3-δ nanofiber cathode for intermediate-temperature solid oxide fuel cells by water-based sol-gel electrospinning: Synthesis and electrochemical behaviour

Water-based sol-gel electrospinning is employed to manufacture perovskite oxide La_0.6Sr_0.4Co_0.2Fe_0.8O_3-δ (LSCF) nanofiber cathodes for intermediate-temperature solid oxide fuel cells. LSCF fibrous scaffolds are synthesized through electrospinning of a sol-gel solution employing water as the only solvent. Morphological characterizations demonstrate that the LSCF fibers have highly crystalline structure with uniform elemental distribution. After heat treatment, the average fiber diameter is 250 nm and the porosity of the nanofiber tissue is 37.5 %. The heat treated LSCF nanofibers are applied directly onto a Ce_0.9Gd_0.1O_1.95 (CGO) electrolyte disk to form a symmetrical cell. Electrochemical characterization is carried out through electrochemical impedance spectroscopy (EIS) in the temperature range 550?°C–950?°C, and reproducibility of the electrochemical performance for a series of cells is demonstrated. At 650?°C, the average measured polarization resistance R_p is 1.0 Ω cm². Measured performance decay is 1 % during the first 33?h of operation at 750?°C, followed by an additional 0.7 % over the subsequent 70?h.