Quartz Crystal Microbalance as Cell-Based Biosensor to Detect and Study Cytoskeletal Alterations and Dynamics

Several techniques can be used to monitor cell dynamism after a perturbation. Among these, Quartz Crystal Microbalance with Dissipation Monitoring (QCM-D) offers the great advantage to study the mechanical properties of cells in real-time and with a great sensitivity. Here, we used QCM-D to investigate the effects of two cytoskeleton-targeting agents, cytochalasin D (CytoD) and Y27632, on human MCF-7 cells. Cell adhesion on the sensor surface, crucial for in-flow experiments, was obtained by covalent adsorption of a fibronectin (FN) film, an extracellular matrix (ECM) protein. Direct analysis of MCF-7 cells on FN-coated sensor, shows a specific cellular response that was revealed and quantified by QCM-D after drugs exposure. Notably, upon treatment with Y27632, we observed a two-regime dissipation behavior that we associated with specific modifications of actin filaments and signaling proteins providing a link between biophysical and molecular mechanisms. Overall, this approach opens new opportunities for studying cellular response to mechanical cues in different biological conditions.

Anticancer effects of novel resveratrol analogues on human ovarian cancer cells

Resveratrol, a naturally occurring phytoalexin, has long been known to play an important regulatory role in key functions in cell physiology. This multifunctional role of resveratrol is explained by its ability to interact with several targets of various cell pathways. In the recent past, synthetic chemical modifications have been made in an attempt to enhance the biological effects of resveratrol, including its anti-cancer properties. In this study, we investigated the molecular mechanisms of action of novel trans-restricted analogues of resveratrol in which the C-C double bond of the natural derivative has been replaced by diaryl-substituted imidazole analogues. In ovarian cancer models, the results of in vitro screening revealed that the resveratrol analogues exhibited enhanced anti-proliferative properties compared with resveratrol. We found that the resveratrol analogues also significantly inhibited Akt and MAPK signalling and reduced the migration of IL-6 and EGF-treated cells. Finally, in ascite-derived cancer cells, we demonstrated that the resveratrol analogues reduced the expression of epithelial mesenchymal transition (EMT) markers. Collectively, these findings indicate the enhanced anti-cancer properties of the resveratrol analogues.

Platinum-induced mitochondrial DNA mutations confer lower sensitivity to paclitaxel by impairing tubulin cytoskeletal organization

Development of chemoresistance is a cogent clinical issue in oncology, whereby combination of anticancer drugs is usually preferred also to enhance efficacy. Paclitaxel (PTX), combined with carboplatin, represents the standard first-line chemotherapy for different types of cancers. We here depict a double-edge role of mitochondrial DNA (mtDNA) mutations induced in cancer cells after treatment with platinum. MtDNA mutations were positively selected by PTX, and they determined a decrease in the mitochondrial respiratory function, as well as in proliferative and tumorigenic potential, in terms of migratory and invasive capacity. Moreover, cells bearing mtDNA mutations lacked filamentous tubulin, the main target of PTX, and failed to reorient the Golgi body upon appropriate stimuli. We also show that the bioenergetic and cytoskeletal phenotype were transferred along with mtDNA mutations in transmitochondrial hybrids, and that this also conferred PTX resistance to recipient cells. Overall, our data show that platinum-induced deleterious mtDNA mutations confer resistance to PTX, and confirm what we previously reported in an ovarian cancer patient treated with carboplatin and PTX who developed a quiescent yet resistant tumor mass harboring mtDNA mutations.

The Many-Faced Program of Epithelial-Mesenchymal Transition: A System Biology-Based View

System biology uses a range of experimental and statistical methods to dissect complex processes that results from alterations in biological models. Given the complexity of the epithelial–mesenchymal transition (EMT) program, system biology represents a promising approach to understanding its fine molecular regulation by the interpretation of high-throughput datasets. Herein, we review recent contributions of system biology applied to the field of EMT physiology and illustrate the importance of these approaches to model biological networks that are perturbed during the transition. Together, these results allowed the definition of an EMT signature across different tumor types, the identification of dysregulated processes and new modules of regulation, making possible to reveal the EMT molecular visage underneath.

Angiogenesis and Vascularization of Uterine Leiomyoma: Clinical Value of Pseudocapsule Containing Peptides and Neurotransmitters

Fibroids or myomas involve large proportion of women of reproductive age. The myoma formation starts from the transformation of the myometrium, causing the progressive formation of a pseudocapsule, which is made of compressed muscle fibers. Numerous studies investigated on myoma pseudocapsule anatomy, discovering many neurotransmitters and neuropeptides, as a neurovascular bundle, influencing myometrial physiology. These substances have a positive impact on wound healing and muscular restoring, also playing a role in sexual and reproductive function. Based on investigations, a distinct surgical technique evolved, called "intracapsular myomectomy", meaning myoma removal from its pseudocapsule, which enables protection of the myoma pseudocapsule, containing neuropeptides and neurofibers involved in physiological myometrial healing. This technique, performed by a gentle myoma enucleating by stretching from myometrium and sparing pseudocapsule, reduces surgical trauma caused by iatrogenic myoma pseudocapsule damage. Intracapsular myomectomy meets the basic surgical anatomy principle: myoma is removed by a bloodless, precise and careful dissection sparing myometrium, as much as possible. The rationale of intracapsular myomectomy should be applied to all myoma removals; therefore, it has been used for both laparoscopic and laparotomic myomectomy, as well as for cesarean myomectomy. Scientific research is still seeks to clarify some reports of myomas with infertility, especially in the case of intramural myomas, but it is clear that in the case of performing myomectomy, it must do by the described intracapsular technique. This enables myometrial preservation, especially peripherally to myoma bed, promoting myometrial healing after myoma removal.

A Proteomic Analysis of Human Uterine Myoma

Uterine leiomyoma is a benign smooth muscle tumor characterized by a high incidence in women of reproductive age. The aetiology of this tumor is still unknown but established risk factors include high levels of female hormones, family history, African ancestry, early age of menarche and obesity. Here, to identify proteomic features associated with this tumor type, we performed a liquid chromatography-mass spectrometry (LC-MS/MS) analysis of uterine myomas. The identified proteins were subjected to a gene ontology analysis to generate biological functions, molecular processes, and protein networks that were relevant to the uploaded dataset. Pathway-based analysis was an effective approach to investigate the molecular mechanisms underlying the disease and to create biological hypotheses about regulation of our proteins including the identification of upstream regulators and main protein nodes. Moreover, proteomic and in silico data were combined with immunohistochemistry and western blotting to identify a group of proteins representative of some selected pathways, with a dysregulated expression in myoma, pseudocapsule, and normal myometrium samples. Based on these results, we confirmed the over-expression of extracellular matrix components, and estrogen and progesterone receptors in uterine myomas, and proposed biological networks, canonical pathways and functions that may be relevant to the pathophysiology of this tumor.

β-Catenin Knockdown Affects Mitochondrial Biogenesis and Lipid Metabolism in Breast Cancer Cells

β-catenin plays an important role as regulatory hub in several cellular processes including cell adhesion, metabolism, and epithelial mesenchymal transition. This is mainly achieved by its dual role as structural component of cadherin-based adherens junctions, and as a key nuclear effector of the Wnt pathway. For this dual role, different classes of proteins are differentially regulated via β-catenin dependent mechanisms. Here, we applied a liquid chromatography-mass spectrometry (LC-MS/MS) approach to identify proteins modulated after β-catenin knockdown in the breast cancer cell line MCF-7. We used a label free analysis to compare trypsin-digested proteins from CTR (shCTR) and β-catenin knockout cells (shβcat). This led to the identification of 98 differentially expressed proteins, 53 of them were up-regulated and 45 down-regulated. Loss of β-catenin induced morphological changes and a significant modulation of the expression levels of proteins associated with primary metabolic processes. In detail, proteins involved in carbohydrate metabolism and tricarboxylic acid cycle were found to be down-regulated, whereas proteins associated to lipid metabolism were found up-regulated in shβcat compared to shCTR. A loss of mitochondrial mass and membrane potential was also assessed by fluorescent probes in shβcat cells with respect to the controls. These data are consistent with the reduced expression of transcriptional factors regulating mitochondrial biogenesis detected in shβcat cells. β-catenin driven metabolic reprogramming resulted also in a significant modulation of lipogenic enzyme expression and activity. Compared to controls, β-catenin knockout cells showed increased incorporation of [1-¹⁴C]acetate and decreased utilization of [U-¹⁴C]glucose for fatty acid synthesis. Our data highlight a role of β-catenin in the regulation of metabolism and energy homeostasis in breast cancer cells.

Abstract 367: Trop-2 activates a dormant Na+/K+-ATPase/PKCα/CD9/ezrin signaling axis to override the basal growth program of cancer cells

Trop-2 is overexpressed in most human cancers, suggesting selective pressure for a key, conserved function. Here we show that Trop-2 stimulates cancer cell growth through the activation of a constitutively expressed, yet otherwise dormant, growth-control module. We discovered that crosslinking of membrane Trop-2 with specific Abs leads to a cytoplasmic Ca2+ raise through interaction with the Na+/K+-ATPase α1 subunit and mobilization of the intracellular stores. This triggers a feed-forward loop through Trop-2-dependent activation and membrane recruitment of PKCα;, which in turn phosphorylates the Trop-2 cytoplasmic tail at two target sites, activating the molecule to stimulate its downstream signaling targets Akt and ERK. Our findings indicate that the Trop-2-triggered cell growth operates through binding and extensive crosstalk with CD9, CD81, CD82 and CD151 through PKCα. Detailed analysis of CD9 and CD81 indicates that they bind to the HIKE region of the Trop-2 intracellular tail. Correspondingly, we found that the HIKE region of Trop-2 mediates its anchoring to the β-actin cytoskeleton through direct interaction with the ERM protein ezrin. Consistently, the Trop-2-dependent dynamic remodeling of the cell cytoskeleton is discovered to occur through activation of myosin II and binding of annexins A1/A11, α-actinin and gelsolin. Systematic drug screening, gene expression silencing and site-directed mutagenesis revealed that cytoskeleton disassembly, HIKE deletion and CD9 inhibition revert the growth of Trop-2-expressing cancer cells to that of their Trop-2-null counterparts. On the other hand, these inhibitors have no effects on basal cell growth. This indicates that Trop-2-centered protein interactions and activations are an essential step for the Trop-2-dependent cancer growth. Tight co-expression of the key components of the Trop-2 growth-stimulatory complex is found in a large breast cancer case series, thus indicating strong clinical relevance. Hence, Trop-2 triggers a universal, but otherwise dormant, layer of cancer growth, that overrides basal cell growth regulatory mechanisms and sensitizes tumors to targeted anticancer therapies.

Citation Format: Marco Trerotola, Valeria Relli, Romina Tripaldi, Andrea Sacchetti, Kristina Havas, Pasquale Simeone, Emanuela Guerra, Annalaura Aloisi, Rossana La Sorda, Rossano Lattanzio, Daniele Vergara, Isabelle Fournier, Michel Salzet, Mauro Piantelli, Saverio Alberti. Trop-2 activates a dormant Na+/K+-ATPase/PKCα/CD9/ezrin signaling axis to override the basal growth program of cancer cells [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 367. doi:10.1158/1538-7445.AM2017-367

The emerging role of GSK-3β in the pathobiology of classical Hodgkin lymphoma

AIMS

Glycogen synthase kinase-3 beta (GSK-3β) is a serine/threonine kinase involved in glycogen metabolism, cell cycle progression, differentiation, embryogenesis, migration, metabolism, survival and cellular senescence. Its main biological function is to inhibit β-catenin by sequestration and promotion of its proteasomal degradation in the Wnt canonical pathway; however, GSK-3β interacts with multiple signalling pathways, and aberrant expression of the enzyme was reported in many solid neoplasms. This study aimed to investigate the biological relevance of GSK-3β in classical Hodgkin lymphomas (cHL).

METHODS AND RESULTS

We analysed the functional status of GSK-3β enzyme in cHL by using antibodies raised against fixation-resistant epitopes of phospho Y216 GSK-3β (active form), phospho S9 GSK-3β (inactive form) and β-catenin protein. We first detected the pY216 GSK-3β active form of the enzyme in 100 of 100 (100%) of the cases, and in line with the latter expression profile, the β-catenin protein was found in only 12 of 100 (12%) of the samples. As reported previously in bladder cancer, pancreatic adenocarcinoma and chronic lymphocytic leukaemia, we showed an aberrant nuclear localization in the neoplastic clone of active pY216 GSK-3β in 78 of 100 (78%) of cHL cases.

CONCLUSIONS

We demonstrated the activation of GSK-3β in cHL resulting in inhibition of the Wnt/β-catenin signal cascade and the aberrant accumulation of its activated form in nuclei of Hodgkin Reed-Sternberg and Hodgkin cells. These findings may be relevant for future clinical studies, identifying GSK-3β as a potential therapeutic target for cHL.

Lipid profiling of parkin-mutant human skin fibroblasts

Parkin mutations are a major cause of early-onset Parkinson's disease (PD). The impairment of protein quality control system together with defects in mitochondria and autophagy process are consequences of the lack of parkin, which leads to neurodegeneration. Little is known about the role of lipids in these alterations of cell functions. In the present study, parkin-mutant human skin primary fibroblasts have been considered as cellular model of PD to investigate on possible lipid alterations associated with the lack of parkin protein. Dermal fibroblasts were obtained from two unrelated PD patients with different parkin mutations and their lipid compositions were compared with that of two control fibroblasts. The lipid extracts of fibroblasts have been analyzed by combined matrix-assisted laser desorption/ionization-time-of-flight mass spectrometry (MALDI-TOF/MS) and thin-layer chromatography (TLC). In parallel, we have performed direct MALDI-TOF/MS lipid analyses of intact fibroblasts by skipping lipid extraction steps. Results show that the proportions of some phospholipids and glycosphingolipids were altered in the lipid profiles of parkin-mutant fibroblasts. The detected higher level of gangliosides, phosphatidylinositol, and phosphatidylserine could be linked to dysfunction of autophagy and mitochondrial turnover; in addition, the lysophosphatidylcholine increase could represent the marker of neuroinflammatory state, a well-known component of PD.

Fats for thoughts: An update on brain fatty acid metabolism

Brain fatty acid (FA) metabolism deserves a close attention not only for its energetic aspects but also because FAs and their metabolites/derivatives are able to influence many neural functions, contributing to brain pathologies or representing potential targets for pharmacological and/or nutritional interventions. Glucose is the preferred energy substrate for the brain, whereas the role of FAs is more marginal. In conditions of decreased glucose supply, ketone bodies, mainly formed by FA oxidation, are the alternative main energy source. Ketogenic diets or medium-chain fatty acid supplementations were shown to produce therapeutic effects in several brain pathologies. Moreover, the positive effects exerted on brain functions by short-chain FAs and the consideration that they can be produced by intestinal flora metabolism contributed to the better understanding of the link between "gut-health" and "brain-health". Finally, attention was paid also to the regulatory role of essential polyunsaturated FAs and their derivatives on brain homeostasis.

Cytoskeletal Alterations and Biomechanical Properties of parkin-Mutant Human Primary Fibroblasts

Parkinson's disease (PD) is one of the most common neurodegenerative diseases. Genes which have been implicated in autosomal-recessive PD include PARK2 which codes for parkin, an E3 ubiquitin ligase that participates in a variety of cellular activities. In this study, we compared parkin-mutant primary fibroblasts, from a patient with parkin compound heterozygous mutations, to healthy control cells. Western blot analysis of proteins obtained from patient's fibroblasts showed quantitative differences of many proteins involved in the cytoskeleton organization with respect to control cells. These molecular alterations are accompanied by changes in the organization of actin stress fibers and biomechanical properties, as revealed by confocal laser scanning microscopy and atomic force microscopy. In particular, parkin deficiency is associated with a significant increase of Young's modulus of null-cells in comparison to normal fibroblasts. The current study proposes that parkin influences the spatial organization of actin filaments, the shape of human fibroblasts, and their elastic response to an external applied force.

Comparative proteomic profiling of Hodgkin lymphoma cell lines

Classical Hodgkin lymphoma (cHL) is a malignancy with complex pathogenesis. The hallmark of the disease is the presence of large mononucleated Hodgkin and bi- or multinucleated Reed/Sternberg (H/RS) cells. The origin of HRS cells in cHL is controversial as these cells show the coexpression of markers of several lineages. Using a proteomic approach, we compared the protein expression profile of cHL models of T- and B-cell derivation to find proteins differentially expressed in these cell lines. A total of 67 proteins were found differentially expressed between the two cell lines including metabolic proteins and proteins involved in the regulation of the cytoskeleton and/or cell migration, which were further validated by western blotting. Additionally, the expression of selected B- and T-cell antigens was also assessed by flow cytometry to reveal significant differences in the expression of different surface markers. Bioinformatics analysis was then applied to our dataset to find enriched pathways and networks, and to identify possible key regulators. In the present study, a proteomic approach was used to compare the protein expression profiles of two cHL cell lines. The identified proteins and/or networks, many of which not previously related to cHL, may be important to better define the pathogenesis of the disease, to identify novel diagnostic markers, and to design new therapeutic strategies.

Translating epithelial mesenchymal transition markers into the clinic: Novel insights from proteomics

The growing understanding of the molecular mechanisms underlying epithelial-to-mesenchymal transition (EMT) may represent a potential source of clinical markers. Despite EMT drivers have not yet emerged as candidate markers in the clinical setting, their association with established clinical markers may improve their specificity and sensitivity. Mass spectrometry-based platforms allow analyzing multiple samples for the expression of EMT candidate markers, and may help to diagnose diseases or monitor treatment efficiently. This review highlights proteomic approaches applied to elucidate the differences between epithelial and mesenchymal tumors and describes how these can be used for target discovery and validation.

A lipidomic approach to the study of human CD4(+) T lymphocytes in multiple sclerosis

Background

Lipids play different important roles in central nervous system so that dysregulation of lipid pathways has been implicated in a growing number of neurodegenerative disorders including multiple sclerosis (MS). MS is the most prevalent autoimmune disorder of the central nervous system, with neurological symptoms caused by inflammation and demyelination. In this study, a lipidomic analysis was performed for the rapid profile of CD4⁺ T lymphocytes from MS patient and control samples in an untargeted approach.

Methods

A matrix-assisted laser desorption/ionization-time of flight (MALDI-TOF) mass spectrometry based approach was used for the analysis of lipid extracts using 9-aminoacridine as matrix. Lipids were analyzed in negative mode and selected species fragmented using MALDI tandem mass spectrometry for their structural assignments.

Results

The analysis reveals some modifications in the phospholipid pattern of MS CD4⁺ T lymphocytes with respect to healthy controls with a significant increase of cardiolipin species in MS samples.

Conclusions

These results demonstrate the feasibility of a MALDI-TOF approach for the analysis of CD4⁺ lipid extracts and suggest how alterations in the lipid metabolism characterized lymphocytes of MS patients.