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Bcl-2 family anti-apoptotic proteins are overexpressed in several hematological and solid tumors, and contribute to tumor formation, progression, and resistance to therapy. They represent a promising therapeutic avenue to explore for cancer treatment. Venetoclax, a Bcl-2 inhibitor is currently used for hematological malignancies or is undergoing clinical trials for either hematological or solid tumors. Despite these progresses, ongoing efforts are focusing on the identification and development of new molecules targeting Bcl-2 protein and/or other family members.

BH3 mimetics, targeting Bcl-2 family anti-apoptotic proteins, represent a promising therapeutic opportunity in tumors. ABT-199, the first specific Bcl-2 inhibitor, has been approved by FDA for treating several hematological malignancies. We have recently discovered IS21, a novel pan BH3 mimetic with preclinical anti-tumor activity in different cancers. This study aimed to evaluate the efficacy of different BH3 mimetics both as single agents, in a panel of different tumor cell histotypes, and in combination with the currently used target therapy in ovarian cancer and melanoma. Our results demonstrate that IS21 reduced the viability of T-cell acute lymphoblastic leukemia, melanoma, lung, pancreatic and ovarian cancer cell lines, and that Bcl-xL and Mcl-1 protein levels were markers of IS21 sensitivity in melanoma and ovarian cancer, respectively. Exploring the IS21 mechanism of action, we reported that IS21 activity was dependent on BAX and BAK proteins, and complexes between Bcl-2 and Bcl-xL proteins and their main binding partners were reduced by IS21. In combination experiments, BH3 mimetics sensitized ovarian cancer cells to the treatment with PARP inhibitors, while IS21 and ABT-199 synergized with MAPK inhibitors in melanoma models both in vitro and in vivo. Through different methodological approaches, we evidenced that the potentiating effect of BH3 mimetics was related to enhancement of apoptotic pathway, both in melanoma and ovarian cancer. In conclusion, our data suggest the use of inhibitors of the anti-apoptotic proteins as a possible therapeutic strategy to enhance the efficacy of target therapy in ovarian cancer and melanoma.

Essential oils (EOs) have been recently emerging for their promising biological activities in preventing tumorigenesis or progression of different tumor histotypes, including melanoma. In this study, we investigated the antitumor activity of a panel of EOs in different tumor models. The ability of Melaleuca alternifolia (tea tree oil) and its main component, terpinen-4-ol, to sensitize the target therapy currently used for melanoma treatment was also assessed. Our results demonstrated that EOs differently affect the viability of human cancer cells and led us to select six EOs effective in melanoma and lung cancer cells, without toxic effects in human fibroblasts. When combined with dabrafenib and/or trametinib, Melaleuca alternifolia synergistically reduced the viability of melanoma cells by activating apoptosis. Through machine learning classification modeling, α-terpineol, tepinolene, and terpinen-4-ol, three components of Melaleuca alternifolia, were identified as the most likely relevant components responsible for the EO’s antitumor effect. Among them, terpinen-4-ol was recognized as the Melaleuca alternifolia component responsible for its antitumor and proapoptotic activity. Overall, our study holds promise for further analysis of EOs as new anticancer agents and supports the rationale for their use to improve target therapy response in melanoma.

Hypoxia, a condition of oxygen deprivation, is considered a hallmark of tumor microenvironment regulating several pathways and promoting cancer progression and resistance to therapy. Semaphorins, a family of about 20 secreted, transmembrane and GPI-linked glycoproteins, and their cognate receptors (plexins and neuropilins) play a pivotal role in the crosstalk between cancer and stromal cells present in the tumor microenvironment. Many studies reported that some semaphorins are involved in the development of a permissive tumor niche, guiding cell-cell communication and, consequently, the development and progression, as well as the response to therapy, of different cancer histotypes, including melanoma.In this review we will summarize the state of art of semaphorins regulation by hypoxic condition in cancer with different origin. We will also describe evidence about the ability of semaphorins to affect the expression and activity of transcription factors activated by hypoxia, such as hypoxia-inducible factor-1. Finally, we will focus our attention on findings reporting the role of semaphorins in melanocytes transformation, melanoma progression and response to therapy. Further studies are necessary to understand the mechanisms through which semaphorins induce their effect and to shed light on the possibility to use semaphorins or their cognate receptors as prognostic markers and/or therapeutic targets in melanoma or other malignancies.

Hypoxia, a condition of low oxygen availability, is a hallmark of tumour microenvironment and promotes cancer progression and resistance to therapy. Many studies reported the essential role of hypoxia in regulating invasiveness, angiogenesis, vasculogenic mimicry and response to therapy in melanoma. Melanoma is an aggressive cancer originating from melanocytes located in the skin (cutaneous melanoma), in the uveal tract of the eye (uveal melanoma) or in mucosal membranes (mucosal melanoma). These three subtypes of melanoma represent distinct neoplasms in terms of biology, epidemiology, aetiology, molecular profile and clinical features.In this review, the latest progress in hypoxia-regulated pathways involved in the development and progression of all melanoma subtypes were discussed. We also summarized current knowledge on preclinical studies with drugs targeting Hypoxia-Inducible Factor-1, angiogenesis or vasculogenic mimicry. Finally, we described available evidence on clinical studies investigating the use of Hypoxia-Inducible Factor-1 inhibitors or antiangiogenic drugs, alone or in combination with other strategies, in metastatic and adjuvant settings of cutaneous, uveal and mucosal melanoma.Hypoxia-Inducible Factor-independent pathways have been also reported to regulate melanoma progression, but this issue is beyond the scope of this review.As evident from the numerous studies discussed in this review, the increasing knowledge of hypoxia-regulated pathways in melanoma progression and the promising results obtained from novel antiangiogenic therapies, could offer new perspectives in clinical practice in order to improve survival outcomes of melanoma patients.

BackgroundA bidirectional crosstalk between tumor cells and the surrounding microenvironment contributes to tumor progression and response to therapy. Our previous studies have demonstrated that bcl-2 affects melanoma progression and regulates the tumor microenvironment. The aim of this study was to evaluate whether bcl-2 expression in melanoma cells could influence tumor-promoting functions of tumor-associated macrophages, a major constituent of the tumor microenvironment that affects anticancer immunity favoring tumor progression.MethodsTHP-1 monocytic cells, monocyte-derived macrophages and melanoma cells expressing different levels of bcl-2 protein were used. ELISA, qRT-PCR and Western blot analyses were used to evaluate macrophage polarization markers and protein expression levels. Chromatin immunoprecipitation assay was performed to evaluate transcription factor recruitment at specific promoters. Boyden chamber was used for migration experiments. Cytofluorimetric and immunohistochemical analyses were carried out to evaluate infiltrating macrophages and T cells in melanoma specimens from patients or mice.ResultsHigher production of tumor-promoting and chemotactic factors, and M2-polarized activation was observed when macrophages were exposed to culture media from melanoma cells overexpressing bcl-2, while bcl-2 silencing in melanoma cells inhibited the M2 macrophage polarization. In agreement, the number of melanoma-infiltrating macrophages in vivo was increased, in parallel with a greater expression of bcl-2 in tumor cells. Tumor-derived interleukin-1β has been identified as the effector cytokine of bcl-2-dependent macrophage reprogramming, according to reduced tumor growth, decreased number of M2-polarized tumor-associated macrophages and increased number of infiltrating CD4+IFNγ+and CD8+IFNγ+effector T lymphocytes, which we observed in response to in vivo treatment with the IL-1 receptor antagonist kineret. Finally, in tumor specimens from patients with melanoma, high bcl-2 expression correlated with increased infiltration of M2-polarized CD163+macrophages, hence supporting the clinical relevance of the crosstalk between tumor cells and microenvironment.ConclusionsTaken together, our results show that melanoma-specific bcl-2 controls an IL-1β-driven axis of macrophage diversion that establishes tumor microenvironmental conditions favoring melanoma development. Interfering with this pathway might provide novel therapeutic strategies.

Evaluating the expression levels of miR-378a-5p both in a large melanoma patient cohort from The Cancer Genome Atlas database and in melanoma patients from our Institute, we found that miR-378a-5p is upregulated in metastatic melanoma specimens. miR-378a-5p expression was also increased in melanoma cells resistant to target therapy, and decreased in response to drug treatment. We also demonstrated that overexpression of miR-378a-5p enhances in vitro cell invasion and migration, and facilitates the ability of melanoma cells to form de novo vasculogenic structures. While performing downstream targeting studies, we confirmed the ability of miR-378a-5p to modulate the expression of known target genes, such as SUFU, FUS-1, and KLF9. Luciferase-3′UTR experiments also identified STAMBP and HOXD10 as new miR-378a-5p target genes. MMP2 and uPAR, two HOXD10 target genes, were positively regulated by miR-378a-5p. Genetic and pharmacologic approaches inhibiting uPAR expression and activity evidenced that the in vitro tumor-promoting functions of miR-378a-5p, were in part mediated by uPAR. Of note miR-378a-5p was also able to increase VEGF, as well as in vitro and in vivo angiogenesis. Finally, genetic and pharmacologic modulation of Bcl-2 evidenced Bcl-2 ability to regulate miR-378a-5p expression. In conclusion, to the best of our knowledge, this is the first study demonstrating that miR-378a-5p acts as an oncogenic microRNA in melanoma.

Melanoma represents the most malignant type of skin cancer, with increasing incidence worldwide [...]

By using human melanoma and glioblastoma cell lines and their derivative BCL-XL overexpressing clones, we investigated the role of BCL-XL in aggressive features of these two tumor histotypes. We found that in both models, BCL-XL overexpression increased in vitro cell migration and invasion and facilitated tumor cells to form de novo vasculogenic structures. Furthermore, BCL-XL overexpressing cells exhibited higher tumors sphere formation capacity and expressed higher levels of some stem cell markers, supporting the concept that BCL-XL plays essential roles in the maintenance of cancer stem cell phenotype. BCL-XL expression reduction by siRNA, the exposure to a BCL-XL-specific inhibitor and the use of a panel of human melanoma cell lines corroborated the evidence that BCL-XL regulates tumor progression-associated properties. Finally, the vascular markers and the vasculogenic mimicry were up-regulated in the BCL-XL overexpressing xenografts derived from both tumor histotypes. In conclusion, our work brings further support to the understanding of the malignant actions of BCL-XL and, in particular, to the concept that BCL-XL promotes stemness and contributes to the aggressiveness of both melanoma and glioblastoma.

Melanoma, the most lethal form of skin cancer, is frequently associated with alterations in several genes, among which the Bcl-2 oncogene plays an important role in progression, chemosensitivity and angiogenesis. Also microRNA (miRNA) are emerging as modulators of melanoma development and progression, and among them, miR-211, located within the melastatin-1/TRPM1 (transient receptor potential cation channel, subfamily M, member 1 protein) gene, is prevalently expressed in the melanocyte lineage and acts as oncosuppressor. Using several human melanoma cell lines and their Bcl-2 stably overexpressing derivatives, we evaluated whether there was a correlation between expression of Bcl-2 and miR-211. Western blot analysis and quantitative real-time polymerase chain reaction demonstrated reduced expression of pri-miR-211, miR-211, TRPM1, and MLANA levels, after Bcl-2 overexpression, associated with increased expression of well-known miR-211 target genes. Overexpression of mature miR-211 in Bcl-2 overexpressing cells rescued Bcl-2 ability to increase cell migration. A decreased nuclear localization of microphthalmia-associated transcription factor (MITF), a co-regulator of both miR-211 and TRPM1, and a reduced MITF recruitment at the TRPM1 and MLANA promoters were also evidenced in Bcl-2 overexpressing cells by immunofluorescence and chromatin immunoprecipitation experiments, respectively. Reduction of Bcl-2 expression by small interference RNA confirmed the ability of Bcl-2 to modulate miR-211 and TRPM1 expression. © 2015 Wiley Periodicals, Inc.

Melanoma, the most aggressive form of skin cancer, is frequently associated with alterations in many genes, among which the Bcl-2 oncogene plays an important role in survival, progression, chemosensitivity and angiogenesis. Also microRNAs play an important role in melanoma development and progression affecting tumor proliferation, migration and invasion. HUVEC and a panel of human melanoma cells were used. Western Blot, qRT-PCR, miRNA Microarray, ELISA, vasculogenic mimicry, cell proliferation, clonogenic and invasion assays have been performed. MiR-378a-5p mimic and inhibitor have been used to study the biological and functional role of miR-378a-5p. In silico analysis have been carried out to find putative miRs targets using miRWalk, Diana Tools and Target Scan. To identify putative miRNAs, whose expression could be modulated by Bcl-2, M14 have been transfected with a smart-pool RNA targeting human Bcl-2 mRNA, and a miRNA Microarray has been performed. Four independent experiments indicate that, after Bcl-2 silencing, 13 miRs were significantly downregulated. Among these, miR-378a-5p, has been identified as significantly deregulated in different human melanoma cell lines. Based on the target prediction analysis, we identified and then confirmed, through qRT-PCR, several miR-378a-5p target genes, such as SUFU, STAMBP and KLF9. By performing in vitro experiments, we found that ectopic expression of miR-378a-5p does not significantly affect cell proliferation and clonogenic ability of melanoma cells, while it significantly increases invasion and the expression of MMP2 at protein level. It also facilitates the ability of tumor cells to form de novo vasculogenic structures. We have also evidences that conditioned medium from miR-378a-5p overexpressing melanoma increases the formation of capillary like structures in endothelial cells. To assess the molecular mechanism through which miR-378a-5p induce angiogenesis, ELISA showed that ectopic expression of miR-378a-5p significantly increases VEGF protein secretion, but not IL-8 mRNA expression. Experiments using an antiVEGF neutralizing antibody indicate VEGF implication on miR-378a-5p-induced vasculogenic mimicry. To identify other factors that may be implicated in miR-378a-5p proangiogenic/proinvasive functions, we focused our attention on Sp1/uPAR axis, a pathway we previously demonstrated to be regulated in cancer cells by Bcl-2 under hypoxic conditions. Our experiments indicate that ectopic expression of miR-378a-5p increases uPAR mRNA expression. Surprisingly, this treatment results in a Sp1 reduction, indicating that other transcription factor, other than Sp1, can be responsible for uPAR induction by miR-378a-5p. Based on these evidences, although a deeper understanding of the molecular mechanism involved in Bcl-2 modulation of miR-378a-5p is needed, our findings strongly suggest a proangiogenic and proinvasive role of miR-378a-5p in melanoma cells. Note: This abstract was not presented at the meeting. Citation Format: Maria Grazia Tupone, Marta Di Martile, Simona D'Aguanno, Elisabetta Valentini, Marianna Desideri, Sara Donzelli, Andrea Sacconi, Daniela Trisciuoglio, Giovanni Blandino, Donatella Del Bufalo. miR-378a-5p acts as a positive regulator of melanoma progression [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 768.

ProNGF, the precursor of mature nerve growth factor (NGF), is the most abundant form of NGF in the brain. ProNGF and mature NGF differ significantly in their receptor interaction properties and in their bioactivity. ProNGF increases markedly in the cortex of Alzheimer's disease (AD) brains and proNGF\NGF imbalance has been postulated to play a role in neurodegeneration. However, a direct proof for a causal link between increased proNGF and AD neurodegeneration is lacking. In order to evaluate the consequences of increased levels of proNGF in the postnatal brain, transgenic mice expressing a furin cleavage-resistant form of proNGF, under the control of the neuron-specific mouse Thy1.2 promoter, were derived and characterized. Different transgenic lines displayed a phenotypic gradient of neurodegenerative severity features. We focused the analysis on the two lines TgproNGF#3 and TgproNGF#72, which shared learning and memory impairments in behavioral tests, cholinergic deficit and increased Aβ-peptide immunoreactivity. In addition, TgproNGF#3 mice developed Aβ oligomer immunoreactivity, as well as late diffuse astrocytosis. Both TgproNGF lines also display electrophysiological alterations related to spontaneous epileptic-like events. The results provide direct evidence that alterations in the proNGF/NGF balance in the adult brain can be an upstream driver of neurodegeneration, contributing to a circular loop linking alterations of proNGF/NGF equilibrium to excitatory/inhibitory synaptic imbalance and amyloid precursor protein (APP) dysmetabolism.

Recent data indicate that some PKC isoforms are translocated to the nucleus, in response to certain stimuli, where they play an important role in nuclear signaling events. To identify novel interacting proteins of conventional PKC (cPKC) at the nuclear level during myogenesis and to find new PKC isozyme-specific phosphosubstrates, we performed a proteomics analysis of immunoprecipitated nuclear samples from mouse myoblast C2C12 cells following insulin administration. Using a phospho(Ser)-PKC substrate antibody, specific interacting proteins were identified by LC-MS/MS spectrometry. A total of 16 proteins with the exact and complete motif recognized by the phospho-cPKC substrate antibody were identified; among these, particular interest was given to eukaryotic elongation factor 1α (eEF1A). Nuclear eEF1A was focalized in the nucleoli, and its expression was observed to increase following insulin treatment. Of the cPKC isoforms, only PKCβI was demonstrated to be expressed in the nucleus of C2C12 myocytes and to co-immunoprecipitate with eEF1A. In-depth analysis using site-directed mutagenesis revealed that PKCβI could phosphorylate Ser53 of the eEF1A2 isoform and that the association between eEF1A2 and PKCβI was dependent on the phosphorylation status of eEF1A2.

Synapses are ultrastructural sites for memory storage in brain, and synaptic damage is the best pathologic correlate of cognitive decline in Alzheimer's disease (AD). Post-translational hyperphosphorylation, enzyme-mediated truncation, conformational modifications, and aggregation of tau protein into neurofibrillary tangles (NFTs) are hallmarks for a heterogeneous group of neurodegenerative disorders, so-called tauopathies. AD is a secondary tauopathy since it is pathologically distinguished by the presence of amyloid-beta (Abeta)-containing senile plaques and the presence of tau-positive NFTs in the neocortex and hippocampus. Here, we report that a 20-22 kDa NH2-truncated tau fragment is largely enriched in human mitochondria from cryopreserved synaptosomes of AD brains and that its amount in terminal fields correlates with the pathological synaptic changes and with the organelle functional impairment. This NH2-truncated tau form is also found in other human, not AD-tauopathies, while its presence in AD patients is linked to Abeta multimeric species and likely to pathology severity. Finally native, patient-derived, Abeta oligomers-enriched extracts likely impair the mitochondrial function by the in vitro production of 20-22 kDa NH2-tau fragments in mature human SY5Y and in rat hippocampal neurons. Thus our findings suggest that the mitochondrial NH2-derived tau peptide distribution may exacerbate the synapse degeneration occurring in tauopathies, including AD, and sustain the in vivo NH-2 tau cleavage inhibitors as an alternative drug discovery strategies for AD therapy.

In the last years, proteomic investigation provided a powerful tool in molecular characterization of complex allergen sources with relevant implications in both diagnosis and immunotherapic treatment of allergies. We followed a proteomic approach to characterize ryegrass (Lolium perenne) pollen, a common cause of seasonal allergic diseases affecting an increasing part of world population. Peptide shotgun experiments performed on nanoLiquid Ultra Pressure Chromatography coupled with fast Q-TOF MS-MS/MS acquisition protocols (MS(E)) and 2-DE immunoblot combined with MALDI-TOF-TOF analysis allowed the detection of all previously identified ryegrass allergens. Comparative analysis of immunoblot highlighted a class of patients characterized by a more complex 2-DE pattern associated with increased levels of IgE antibodies and by higher susceptibility to multiple sensitization toward different allergen sources. Cluster analysis revealed that all these patients recognized profilin, considered the main cross-reactive allergen in grass pollen. Furthermore, mass spectrometry analysis revealed the presence of other IgE reactive components in ryegrass pollen that might be involved in polysensitization, such as cyclophilin, fructosyltransferase and legumin-like protein.

Liver has a principal role in glucose regulation and lipids homeostasis. It is under a complex control by substrates such as hormones, nutrients, and neuronal impulses. Insulin promotes glycogen synthesis, lipogenesis, and lipoprotein synthesis and inhibits gluconeogenesis, glycogenolysis, and VLDL secretion by modifying the expression and enzymatic activity of specific molecules. To understand the pathophysiological mechanisms leading to metabolic liver disease, we analyzed liver protein patterns expressed in a mouse model of diabetes by proteomic approaches. We used insulin receptor-knockout (IR−/−) and heterozygous (IR+/−) mice as a murine model of liver metabolic dysfunction associated with diabetic ketoacidosis and insulin resistance. We evaluated liver fatty acid levels by microscopic examination and protein expression profiles by orthogonal experimental strategies using protein 2-DE MALDI-TOF/TOF and peptic nLC-MS/MS shotgun profiling. Identified proteins were then loaded into Ingenuity Pathways Analysis to find possible molecular networks. Twenty-eight proteins identified by 2-DE analysis and 24 identified by nLC-MS/MS shotgun were differentially expressed among the three genotypes. Bioinformatic analysis revealed a central role of high-mobility group box 1/2 and huntigtin never reported before in association with metabolic and related liver disease. A different modulation of these proteins in both blood and hepatic tissue further suggests their role in these processes. These results provide new insight into pathophysiology of insulin resistance and hepatic steatosis and could be useful in identifying novel biomarkers to predict risk for diabetes and its complications.

Recently, Irani and colleagues proposed a C-terminal cleaved isoform cystatin C (12.5kDa) in cerebrospinal fluid as a marker of multiple sclerosis. In this study, we demonstrate that the 12.5kDa product of cystatin C is formed by degradation of the first eight N-terminal residues. Moreover, such a degradation is not specific in the cerebrospinal fluid of multiple sclerosis, but rather is given by an inappropriate sample storage at −20°C. We conclude that the use of the 12.5kDa product of cystatin C in cerebrospinal fluid might lead to a fallacious diagnosis of multiple sclerosis. Preanalytical validation procedure is mandatory for proteomics investigations. Ann Neurol 2007

Conversion of glutamate 1-semialdehyde to the tetrapyrrole precursor, 5-aminolevulinate, takes place in an aminomutase-catalyzed reaction involving transformations at both the non-chiral C5 and the chiral C4 of the intermediate 4,5-diaminovalerate. Presented with racemic diaminovalerate and an excess of succinic semialdehyde, the enzyme catalyzes a transamination in which only the l-enantiomer is consumed. Simultaneously, equimolar 4-aminobutyrate and aminolevulinate are formed. The enzyme is also shown to transaminate aminolevulinate and 4-aminohexenoate to l-diaminovalerate as the exclusive amino product. The interaction of the enzyme with pure d- and l-enantiomers of diaminovalerate prepared by these reactions is described. Transamination of l-diaminovalerate yielded aminolevulinate quantitatively showing that reaction at the C5 amine does not occur significantly. A much slower transamination reaction was catalyzed with d-diaminovalerate as substrate. One product of this reaction, 4-aminobutyrate, was formed in the amount equal to that of the diaminovalerate consumed. Glutamate semialdehyde was deduced to be the other primary product and was also measured in significant amounts when a high concentration of the enzyme in its pyridoxal form was reacted with d-diaminovalerate in a single turnover. Single turnover reactions showed that both enantiomers of diaminovalerate converted the enzyme from its 420-nm absorbing pyridoxaldimine form to the 330-nm absorbing pyridoxamine via rapidly formed intermediates with different absorption spectra. The intermediate formed with l-DAVA (lambdamax = 420 nm) was deduced to be the protonated external aldimine with the 4-amino group. The intermediate formed with d-DAVA (lambdamax = 390 nm) was deduced to be the unprotonated external aldimine with the 5-amino group.

Vitamin B(6)-dependent enzymes may be grouped into five evolutionarily unrelated families, each having a different fold. Within fold type I enzymes, L-threonine aldolase (L-TA) and fungal alanine racemase (AlaRac) belong to a subgroup of structurally and mechanistically closely related proteins, which specialised during evolution to perform different functions. In a previous study, a comparison of the catalytic properties and active site structures of these enzymes suggested that they have a catalytic apparatus with the same basic features. Recently, recombinant D-threonine aldolases (D-TAs) from two bacterial organisms have been characterised, their predicted amino acid sequences showing no significant similarities to any of the known B(6) enzymes. In the present work, a comparative structural analysis suggests that D-TA has an alpha/beta barrel fold and therefore is a fold type III B(6) enzyme, as eukaryotic ornithine decarboxylase (ODC) and bacterial AlaRac. The presence of both TA and AlaRac in two distinct evolutionary unrelated families represents a novel and interesting example of convergent evolution. The independent emergence of the same catalytic properties in families characterised by completely different folds may have not been determined by chance, but by the similar structural features required to catalyse pyridoxal phosphate-dependent aldolase and racemase reactions.

Bcl-xL is an antiapoptotic protein highly expressed in cancer and contributes to tumor initiation and progression by promoting cell survival. It also promotes tumor angiogenesis and metastasis. By using M14 melanoma and ADF glioblastoma cell lines and their derivative bcl-xL overexpressing clones, in the current study, we investigated the role of bcl-xL in aggressive features of melanoma and glioblastoma models. We found that in both models, bcl-xL overexpression increased in vitro cell migration and invasion and facilitated tumor cells to form de novo vasculogenic structures. Furthermore, bcl-xL overexpressing cells exhibited significantly higher tumorsphere formation capacity, reflecting the self-renewal activity, and expressed high levels of some stem cell markers, supporting the concept that bcl-xL plays essential roles in the maintenance of cancer stem cells phenotype. Forced expression of bcl-xL in melanoma cells also increased vascular endothelial growth factor (VEGF) and matrix metalloprotease-2 (MMP-2) expression, and the activation of hypoxia-inducible factor 1 (HIF-1), a key pathway involved in melanoma vascularization and aggressiveness. On the contrary, no differences were observed after bcl-xL overexpression in glioblastoma model, in terms of HIF-1 expression and activity, and VEGF protein secretion. Immunohistochemical analysis revealed that the expression of the vascular markers, and the vasculogenic mimicry were upregulated in the bcl-xL overexpressing xenografts derived from both tumor histotypes. The work presented here brings further support to the understanding of the malignant actions of bcl-xL both in melanoma and glioblastoma, and in particular to the concept that bcl-xL contributes to the aggressiveness of these two tumor histotypes by promoting invasion, migration, vasculogenic mimicry and cancer stem cells phenotype. It also indicates a cell type-specific effect of bcl-xL on HIF-1/VEGF axis. Citation Format: Maria Grazia Tupone, Daniela Trisciuoglio, Marianna Desideri, Marta Di Martile, Chiara Gabellini, Simonetta Buglioni, Laura De Salvo, Gabriele Alessandrini, Simona D'Aguanno, Donatella Del Bufalo. Bcl-xL overexpression promotes tumor aggressiveness [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 933. doi:10.1158/1538-7445.AM2017-933

A number of studies suggest that cancer stem cells are essential for tumour growth, and failure to target these cells can result in tumour relapse. As this population of cells has been shown to be resistant to radiation and chemotherapy, it is essential to understand their biology and identify new therapeutic approaches. Targeting cancer metabolism is a potential alternative strategy to counteract tumour growth and recurrence. Here we applied a proteomic and targeted metabolomic analysis in order to point out the main metabolic differences between breast cancer cells grown as spheres and thus enriched in cancer stem cells were compared with the same cells grown in adherent differentiating conditions. This integrated approach allowed us to identify a metabolic phenotype associated with the stem-like condition and shows that breast cancer stem cells (BCSCs) shift from mitochondrial oxidative phosphorylation towards fermentative glycolysis. Functional validation of proteomic and metabolic data provide evidences for increased activities of key enzymes of anaerobic glucose fate such as pyruvate kinase M2 isoform, lactate dehydrogenase and glucose 6-phopshate dehydrogenase in cancer stem cells as well as different redox status. Moreover, we show that treatment with 2-deoxyglucose, a well known inhibitor of glycolysis, inhibits BCSC proliferation when used alone and shows a synergic effect when used in combination with doxorubicin. In conclusion, we suggest that inhibition of glycolysis may be a potentially effective strategy to target BCSCs.

p63 is an important regulator of epithelial development expressed in different variants containing (TA) or lacking (ΔN) the N-terminal transactivation domain. The different isoforms regulate stem-cell renewal and differentiation as well as cell senescence. Several studies indicate that p63 isoforms also play a role in cancer development; however, very little is known about the role played by p63 in regulating the cancer stem phenotype. Here we investigate the cellular signals regulated by TAp63 and ΔNp63 in a model of epithelial cancer stem cells. To this end, we used colon cancer stem cells, overexpressing either TAp63 or ΔNp63 isoforms, to carry out a proteomic study by chemical-labeling approach coupled to network analysis. Our results indicate that p63 is implicated in a wide range of biological processes, including metabolism. This was further investigated by a targeted strategy at both protein and metabolite levels. The overall data show that TAp63 overexpressing cells are more glycolytic-active than ΔNp63 cells, indicating that the two isoforms may regulate the key steps of glycolysis in an opposite manner. The mass-spectrometry proteomics data of the study have been deposited to the ProteomeXchange Consortium ( http://proteomecentral.proteomexchange.org ) via the PRIDE partner repository with data set identifiers PXD000769 and PXD000768.

L-threonine aldolases (L-TAs) represent a family of homologous pyridoxal 5'-phosphate-dependent enzymes found in bacteria and fungi, and catalyse the reversible cleavage of several L-3-hydroxy-α-amino acids. L-TAs have great biotechnological potential, as they catalyse the formation of carbon-carbon bonds, and therefore may be exploited for the bioorganic synthesis of L-3-hydroxyamino acids that are biologically active or constitute building blocks for pharmaceutical molecules. Many L-TAs, showing different stereospecificity towards the Cβ configuration, have been isolated. Because of their potential to carry out diastereoselective syntheses, L-TAs have been subjected to structural, functional and mechanistic studies. Nevertheless, their catalytic mechanism and the structural bases of their stereospecificity have not been elucidated. In this study, we have determined the crystal structure of low-specificity L-TA from Escherichia coli at 2.2-A resolution, in the unliganded form and cocrystallized with L-serine and L-threonine. Furthermore, several active site mutants have been functionally characterized in order to elucidate the reaction mechanism and the molecular bases of stereospecificity. No active site catalytic residue was revealed, and a structural water molecule was assumed to act as the catalytic base in the retro-aldol cleavage reaction. Interestingly, the very large active site opening of E. coli L-TA suggests that much larger molecules than L-threonine isomers may be easily accommodated, and L-TAs may actually have diverse physiological functions in different organisms. Substrate recognition and reaction specificity seem to be guided by the overall microenvironment that surrounds the substrate at the enzyme active site, rather than by one ore more specific residues.

Cyclosporin A, a cyclic peptide produced by the fungus Tolypocladium inflatum, is a widely employed immunosuppressant drug. Its biosynthesis is strictly dependent on the action of the pyridoxal 5′-phosphate-dependent enzyme alanine racemase, which produces the d -alanine incorporated in the cyclic peptide. This enzyme has a different fold with respect to bacterial alanine racemases. The interest elicited by T. inflatum alanine racemase not only relies on its biotechnological relevance, but also on its evolutionary and structural similarity to the promiscuous enzymes serine hydroxymethyltransferase and threonine aldolase. The three enzymes represent a model of divergent evolution from an ancestral enzyme that was able to catalyse all the reactions of the modern enzymes. A protocol to express and purify with high yield recombinant T. inflatum alanine racemase was developed. The catalytic properties of the enzyme were characterized. Similarly to serine hydroxymethyltransferase and threonine aldolase, T. inflatum alanine racemase was able to catalyse retroaldol cleavage and transamination reactions. This observation corroborates the hypothesis of the common evolutionary origin of these enzymes. A three-dimensional model of T. inflatum alanine racemase was constructed on the basis of threonine aldolase crystal structure. The model helped rationalise the experimental data and explain the catalytic properties of the enzymes.

Members of the bcl-2 protein family share regions of sequence similarity, the bcl-2 homology (BH) domains. Bcl-2, the most studied member of this family, has four BH domains, BH1–4, and has a critical role in resistance to antineoplastic drugs by regulating the mitochondrial apoptotic pathway. Moreover, it is also involved in other relevant cellular processes such as tumor progression, angiogenesis and autophagy. Deciphering the network of bcl-2-interacting factors should provide a critical advance in understanding the different functions of bcl-2. Here, we characterized bcl-2 interactome by mass spectrometry in human lung adenocarcinoma cells. In silico functional analysis associated most part of the identified proteins to mitochondrial functions. Among them we identified SRA stem–loop interacting RNA-binding protein, SLIRP, a mitochondrial protein with a relevant role in regulating mitochondrial messenger RNA (mRNA) homeostasis. We validated bcl-2/SLIRP interaction by immunoprecipitation and immunofluorescence experiments in cancer cell lines from different histotypes. We showed that, although SLIRP is not involved in mediating bcl-2 ability to protect from apoptosis and oxidative damage, bcl-2 binds and stabilizes SLIRP protein and regulates mitochondrial mRNA levels. Moreover, we demonstrated that the BH4 domain of bcl-2 has a role in maintaining this binding.

Transthyretin (TTR) is a homotetrameric protein of the CNS that plays a role of as the major thyroxine (T4) carrier from blood to cerebrospinal fluid (CSF). T4 physiologically helps oligodendrocyte precursor cells to turn into myelinating oligodendrocytes, enhancing remyelination after myelin sheet damage. We investigated post-translational oxidative modifications of serum and CSF TTR in multiple sclerosis subjects, highlighting high levels of S-sulfhydration and S-sulfonation of cysteine in position ten only in the cerebral TTR, which correlate with an anomalous TTR protein folding as well as with disease duration. Moreover, we found low levels of free T4 in CSF of multiple sclerosis patients, suggestive of a potential role of these modifications in T4 transport into the brain.

The Ubiquitin-Proteasome System (UPS) and the Autophagy-Lysosome Pathways (ALP) are key mechanisms for cellular homeostasis sustenance and protein clearance. A wide number of Neurodegenerative Diseases (NDs) are tied with UPS impairment and have been also described as proteinopathies caused by aggregate-prone proteins, not efficiently removed by proteasome. Despite the large knowledge on proteasome biological role, molecular mechanisms associated with its impairment are still blur. We have pursued a comprehensive proteomic investigation to evaluate the phenotypic rearrangements in protein repertoires associated with a UPS blockage. Different functional proteomic approaches have been employed to tackle UPS impairment impact on human NeuroBlastoma (NB) cell lines responsive to proteasome inhibition by Epoxomicin. 2-Dimensional Electrophoresis (2-DE) separation combined with Mass Spectrometry and Shotgun Proteomics experiments have been employed to design a thorough picture of protein profile. Unsupervised meta-analysis of the collected proteomic data revealed that all the identified proteins relate each other in a functional network centered on beta-estradiol. Moreover we showed that treatment of cells with beta-estradiol resulted in aggregate removal and increased cell survival due to activation of the autophagic pathway. Our data may provide the molecular basis for the use of beta-estradiol in neurodegenerative disorders by induction of protein aggregate removal.

Curcumin is a natural compound with recognized anti-inflammatory properties, but its anticancer activity is still object of study. We provided an unsupervised molecular investigation of the main proteome rearrangements involved in the cellular response to curcumin in a human neuroblastoma cell line sensitive to cisplatin and its resistant counterpart by a comparative proteomic approach. Shotgun analysis demonstrated that 66 proteins were differentially expressed in response to 24 h treatment with 40 μM curcumin in sensitive cells, whereas 32 proteins were significantly modulated in treated resistant cells. Functional analysis revealed that proteins involved in cellular assembly and organization, biosynthesis and glycolysis were down-regulated by curcumin treatment. Proteome changes were associated to cell cycle arrest in the G2/M phase and accumulation of polyubiquitinated proteins, also confirmed by flow cytometry and immunoblotting analysis, but not to a significant increment of reactive oxygen species production. Since the polyubiquitination of proteins influences a wide range of cellular pathways, the inhibition of the ubiquitin-proteasome system may be the main way through which curcumin performs its multi-target activity.

Primary open angle (POAG) and pseudoexfoliative glaucoma (PXG) are the most common primary and secondary forms of glaucoma, respectively. Even though the patho-physiology, aqueous humor composition, risk factors, clinical features, therapy and drug induced ocular surface changes in POAG and PXG have been widely studied, to date information concerning tear protein characterization is lacking. Tears are a source of nourishment for ocular surface tissues and a vehicle to remove local waste products, metabolized drugs and inflammatory mediators produced in several ophthalmic diseases. In glaucoma, the proteomic definition of tears may provide insights concerning patho-physiology of the disease and ocular surface modifications induced by topical therapy. Our study aimed at characterizing protein patterns in tears of patients with medically controlled POAG and PXG. A comparative tears proteomic analysis by label-free LC-MS(E) highlighted differences in the expression of several proteins in the two glaucoma sub-types and control subjects, highlighting inflammation pathways expressed in both diseases. Results were independently reconfirmed by SDS-PAGE and linear MALDI-TOF MS, validating altered levels of Lysozyme C, Lipocalin-1, Protein S100, Immunoglobulins and Prolactin Inducible Protein. Moreover, we found a differential pattern of phosphorylated Cystatin-S that distinguishes the two pathologies. The most relevant results suggest that in both pathologies there may be active inflammation pathways related to the disease and/or induced by therapy. We show, for the first time, tear protein patterns expressed under controlled intraocular pressure conditions in POAG and PXG subjects. These findings could help in the understanding of molecular machinery underlying these ophthalmologic diseases, resulting in early diagnosis and more specific therapy.

The effect of the glutathione transferase P1-1 (GSTP1-1) targeting has been investigated in both sensitive (U-2OS) and cisplatin-resistant (U-2OS/CDDP4 μg) human osteosarcoma cell lines. Despite the different enzyme's content, inhibition of GSTP1-1 by 6-(7-nitro-2,1,3-benzoxadiazol-4-ylthio)hexanol (NBDHEX) causes the activation of c-Jun N-terminal kinase (JNK) and apoptosis in both cell lines. However, different time courses of JNK activation and cell responses are observed. Whereas in the U-2OS/CDDP4 μg cell line drug treatment results in an early increase of caspase activity and secondary necrosis, in the U-2OS cells it mainly causes an early cell cycle arrest followed by apoptosis. In order to elucidate the action mechanism of NBDHEX we performed a proteomic investigation by label-free nLC-MS(E). The high-throughput analysis associated with a bioinformatic tool suggested the involvement of the TNF receptor associated factor (TRAF) family in the cellular response to the drug treatment. We report experimental evidence of the interaction between GSTP1-1 and TRAF2 and we demonstrate that NBDHEX is able to dissociate the GSTP1-1 : TRAF2 complex. This restores the TRAF2 : ASK1 signaling, thereby leading to the simultaneous and prolonged activation of JNK and p38. These mitogen-activated protein kinases (MAPKs) mediate different effects: JNK is crucial for apoptosis, whereas p38 causes an increase in the p21 level and a concomitant cell cycle arrest. Our study shows that GSTP1-1 plays an important regulatory role in TRAF signaling of osteosarcoma and discloses new features of the action mechanism of NBDHEX that suggest potentially practical consequences of these findings.

Recent data indicate that some PKC isoforms are translocated to the nucleus, in response to certain stimuli, where they play an important role in nuclear signaling events. To identify novel interacting proteins of conventional PKC (cPKC) at the nuclear level during myogenesis and to find new PKC isozyme-specific phosphosubstrates, we performed a proteomics analysis of immunoprecipitated nuclear samples from mouse myoblast C2C12 cells following insulin administration. Using a phospho(Ser)-PKC substrate antibody, specific interacting proteins were identified by LC-MS/MS spectrometry. A total of 16 proteins with the exact and complete motif recognized by the phospho-cPKC substrate antibody were identified; among these, particular interest was given to eukaryotic elongation factor 1α (eEF1A). Nuclear eEF1A was focalized in the nucleoli, and its expression was observed to increase following insulin treatment. Of the cPKC isoforms, only PKCβI was demonstrated to be expressed in the nucleus of C2C12 myocytes and to co-immunoprecipitate with eEF1A. In-depth analysis using site-directed mutagenesis revealed that PKCβI could phosphorylate Ser53 of the eEF1A2 isoform and that the association between eEF1A2 and PKCβI was dependent on the phosphorylation status of eEF1A2.

Protein profiling of cerebrospinal fluid in Guillain-Barre syndrome (GBS), an acute and immune-mediated disease affecting the peripheral nervous system, was performed by two-dimensional electrophoresis. Significant modulated spots in GBS patients vs. control groups (a group of multiple sclerosis patients and one of healthy donors) underwent MALDI-TOF/TOF investigation. Inflammation-related proteins, such as vitamin D-binding protein, beta-2 glycoprotein I (ApoH), and a complement component C3 isoform were up-regulated in GBS, whereas transthyretin (the monomer and the dimer forms), apolipoprotein E, albumin and five of its fragments were down-regulated. Then, we used an isoelectric-focusing-dinitrophenylhydrazine-based technique to analyse the extent of carbonylation and, as a result, of oxidative damage of GBS CSF proteome. We observed a major sensitivity to carbonylation for albumin and alpha-glycoprotein in inflammation and a selective increase of reactivity for a glycosylated Fab from an IgM globulin in GBS CSF. Our results add new proteins to candidate CSF features of GBS, and suggest that oxidative stress could contribute to the immunopathological mechanisms in this syndrome.

Vav1, whose physiological expression is restricted to hematopoietic system, is one of the signaling proteins up-regulated by all-trans retinoic acid (ATRA) in acute promyelocytic leukemia (APL)-derived precursors, in which it promotes the overcoming of the differentiation blockade. High levels of tyrosine phosphorylated Vav1 accumulate in differentiating APL-derived cells, suggesting that one or more Vav1 tyrosine residues are involved in neutrophil differentiation of tumoral promyelocytes. Here, we have found that phosphorylation of Vav1 Y174, that is known to regulate Vav1 activity in mature neutrophils, is up-regulated by ATRA in NB4 cells. Nevertheless, this tyrosine residue does not seem crucial for the agonist-induced phenotypical differentiation of APL-derived cells. Mass spectrometry analysis performed on Vav1 from differentiating NB4 cells allowed to identify the highly conserved Y745 residue as a phosphorylated tyrosine that plays crucial roles in the completion of the maturation program of this cell line. In fact, the overexpression of a mutated form of Vav1, in which Y745 was replaced with a phenylalanine, significantly reduced the ATRA-induced CD11b expression and essentially abrogated the differentiation-related acquisition of the migratory capability. Even though the intracellular signaling involving Vav1 phosphorylated in Y745 is unknown, the identification of a tyrosine residue essential for differentiation of tumoral precursors may constitute the basis to identify new specific targets for differentiation therapy of APL.

Background: Data have accumulated implicating the involvement of oncogenic human papillomaviruses (HPVs) in bronchial carcinogenesis. We recently described the presence of oncogenic HPV transcripts in non-small cell lung cancers. Objective: To investigate the role of oncogenic HPVs in lung carcinogenesis. Material and Methods: The lung cell line A549 stably infected with HPV16E6, HPV16E7 and HPVE6/E7 constructs was used to investigate the protein profile changes associated with the expression of these oncogenes. Replicated two-dimensional gel electrophoresis gels from uninfected and stably HPV16E6-, E7-, and E6/E7-infected A549 cells were compared for changes in protein profile. Protein identification was achieved by peptide mass fingerprinting by MALDI-TOF-MS and nLC-ESI-Q-TOF-MS/MS peptide ladder sequencing. Results: We identified 17 different polypeptides whose average normalized spot intensity was statistically significant (p < 0.05) and differed by 2-fold. Relationships between differentially expressed proteins and the HPV-induced infection mechanism have been clustered by knowledge-base database functional association network analysis. Conclusion: The impact of Hsp27, annexin III, annexin IV, Gp96 and TPT1 on the cellular response mechanism to HPV infection is presented and discussed.

Aberrations in the Ubiquitin-Proteasome System (UPS) have been recently connected to the pathogenesis of several human protein degradation disorders (e.g., cancer and neurodegenerative diseases), so that proteasome is now considered an important target for drug discovery. Small molecules able to inhibit and modulate UPS have been, in fact, described as novel tools for a new approach in anti-cancer therapy. In particular Proteasome Inhibitors (PIs), blocking activation of nuclear factor-kappa B (NF-kB), trigger a decreased cellular proliferation and angiogenic cytokine production, induce cell death and inhibit tumor cell adhesion to stroma. Furthermore, several studies have demonstrated that PIs potentiate the activity of other anti-cancer treatment, in part by down-regulating chemoresistance pathways. Therefore pharmacologic, preclinical, and clinical data suggested the use of PIs in anticancer strategies, for their potential therapeutic relevance in the treatment of cancer and inflammatory-related diseases. This review focuses on recent advances in the development of PIs anticancer agents highlighting both novel patented compounds and novel therapeutic protocol of intervention.

Leber's hereditary optic neuropathy (LHON) is a genetic disease leading to the loss of central vision and optic nerve atrophy. The existence of occasional cases of LHON patients developing a Multiple Sclerosis (MS)-like illness and the hypothesis that mtDNA variants may be involved in MS suggest the possibility of some common molecular mechanisms linking the two diseases. We have pursued a comparative proteomics approach on cerebrospinal fluid (CSF) samples from LHON and MS patients, as well as healthy donors by employing 2-DE gel separations coupled to MALDI-TOF-MS and nLC-MS/MS investigations. 7 protein spots showed significant differential distribution among the three groups. Both CSF of LHON or MS patients are characterized by lower level of transthyretin dimer adduct while a specific up regulation of Apo A-IV was detected in LHON CSF.

The cerebrospinal fluid (CSF) is a key sample in the research for novel molecular biomarkers of neurodegenerative disorders. CSF represents a repertoire of neuro-secreted, biosynthesised and metabolised molecular products of the central nervous system (CNS). Diffusion of macromolecules from the peripheral circulatory system to the CSF is highly regulated by the blood-brain barrier, which prevents uncontrolled distribution of proteins in the CNS. The development of reproducible high resolution separations of proteins in 2-D electrophoresis methods by the advent of immobilised pH gradient has opened the route to multivariate holistic protein pattern investigation of CSF into neurodegenerative disorders. Moreover, the introduction of pre-fractionation techniques such as free flow electrophoresis is currently increasing the dynamic depth of proteome analysis. Alzheimer's disease (AD) and other forms of dementia, demyelinating diseases, Parkinson's disease (PD), and Creutzfeldt-Jakob disease (CJD) have been evaluated for biomarker discovery by CSF investigation in multiple studies. However, the statistical design of these clinical cross-sectional investigations remains a limited factor given the strong statistical power required for complex multivariate analysis. These initial evidences are of particular interest in dissecting specific molecular mechanisms. The development of fast and economic profiling of CSF by linear matrix assisted laser desorption ionisation time-of-flight mass spectrometry (MALDI-TOF-MS) is providing a new ancillary technology to assess sample quality and pre-analytical requirements. In the following we take into account all these issues in the CSF proteomics investigation, especially highlighting the possible application in the development of clinical molecular biomarkers.Clin Chem Lab Med 2007;45:437–49.