Mirco Zucchelli

Breast cancer stem cells rely on fermentative glycolysis and are sensitive to 2-deoxyglucose treatment

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.

Metabolomics signature improves the prediction of cardiovascular events in elderly subjects

AIMS Age is one of the most important determinants of cardiovascular health, therefore the management of cardiovascular diseases (CVD) in elderly people entails great challenge. A possible explanation of vascular senescence process is the mitochondrial damage and dysfunction. We hypothesized that metabolomic profiling would identify biomarkers predicting major cardiovascular events (MACEs) in elderly people, improving the clinical standard cardiovascular risk factors. METHODS AND RESULTS Targeted-mass-spectrometry-based profiling of 49 metabolites was performed in a group of very old participants (n = 67, mean age = 85 ± 3 years) with a high rate of previous CVD (68%). Principal Component Analysis, Random Survival Forest analysis and Cox proportional hazards regression modeling were used to evaluate the relation between the metabolite factors and recurring MACEs. We tested discrimination ability and reclassification of clinical and metabolomic models. At follow-up (median = 3.5 years), 17 MACEs occurred (5 cardiovascular deaths, 1 nonfatal myocardial infarction, 7 nonfatal strokes and 4 peripheral artery surgeries) (incidence = 7.3% person-years). Metabolite factor 1, composed by medium- and long-chain acylcarnitines, and factor 7 (alanine) were independently associated with MACEs, after adjustment for clinical CV covariates [HR = 1.77 (95%CI = 1.11-2.81, p = 0.016) and HR = 2.18 (95%CI = 1.17-4.07, p = 0.014), respectively]. However, only factor 1 significantly increases the prediction accuracy of the Framingham Recurring-Coronary-Heart-Disease-Score, with a significant improvement in discrimination (integrated discrimination improvement = 7%, p = 0.01) and correctly reclassifying 41% of events and 37% of non-events resulting in a cNRI = 0.79 (p = 0.005). CONCLUSIONS Aging mitochondrial dysfunction evaluated by metabolomic profiling is associated with MACEs, independently of standard predictors.

Reappraisal of the clinical pharmacology of low-dose aspirin by comparing novel direct and traditional indirect biomarkers of drug action

Even though the acetylation of platelet cyclooxygenase (COX)‐1 at serine‐529 is the direct mechanism of action of low‐dose aspirin, its antiplatelet effect has been characterized using indirect indexes of COX‐1 activity.

Toward personalized hemodialysis by low molecular weight amino-containing compounds: future perspective of patient metabolic fingerprint

BACKGROUND L-carnitine deficiency is commonly observed in chronic hemodialysis patients, and this depletion may cause clinical symptoms like muscle weakness, anaemia, and hypotension. MATERIALS AND METHODS We pursued a targeted metabonomics investigation in 28 hemodialysis patients (13 non diabetics and 15 diabetics) and in 10 age-matched healthy controls, on plasma levels of all carnitine esters and of several amino acids. Samples were taken before and after the first hemodialysis treatment of the week. Multiplexed data were collected in LCMRM (Multiple Reaction Monitoring) and analysed by unsupervised multivariate analysis. RESULTS In diabetic uremic patients, we observed lower values of propionylcarnitine than in other groups, while acylcarnitine concentration was higher in uremics compared to controls. The hemodialysis session induced a decline in free, short-chain, medium-chain and dicarboxylic acylcarnitines, whereas the long chain acylcarnitines remained unaffected. Plasma levels of amino acid proline, ornithine, citrulline and serine were significantly elevated in uremic patients before dialysis compared to controls. For most tested plasma amino acids, a significant reduction after hemodialysis session was found. DISCUSSION Our study is the first that investigated on possible modifications of the system of carnitine in diabetic patients in hemodialysis not only in relation to the condition of deficiency but also compared to lipid and glucose homeostasis alteration typical of diabetics. We proposed the application of targeted metabolic fingerprint in the management of the hemodialysis patients.

p63 isoforms regulate metabolism of cancer stem cells

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.

Proteomic profiling of ATM kinase proficient and deficient cell lines upon blockage of proteasome activity

Ataxia Telangiectasia Mutated (ATM) protein kinase is a key effector in the modulation of the functionality of some important stress responses, including DNA damage and oxidative stress response, and its deficiency is the hallmark of Ataxia Telangiectasia (A-T), a rare genetic disorder. ATM modulates the activity of hundreds of target proteins, essential for the correct balance between proliferation and cell death. The aim of this study is to evaluate the phenotypic adaptation at the protein level both in basal condition and in presence of proteasome blockage in order to identify the molecules whose level and stability are modulated through ATM expression. We pursued a comparative analysis of ATM deficient and proficient lymphoblastoid cells by label-free shotgun proteomic experiments comparing the panel of proteins differentially expressed. Through a non-supervised comparative bioinformatic analysis these data provided an insight on the functional role of ATM deficiency in cellular carbohydrate metabolisms regulation. This hypothesis has been demonstrated by targeted metabolic fingerprint analysis SRM (Selected Reaction Monitoring) on specific thermodynamic checkpoints of glycolysis. This article is part of a Special Issue entitled: Translational Proteomics.

Low-Dose Aspirin Acetylates Cyclooxygenase-1 in Human Colorectal Mucosa: Implications for the Chemoprevention of Colorectal Cancer

The mechanism of action of low‐dose aspirin in the prevention of colorectal cancer (CRC) remains largely hypothetical. We aimed to compare the effects of low‐dose aspirin (100 mg/day for 7 days) given to 40 individuals undergoing CRC screening on the extent of cyclooxygenase (COX)‐1 acetylation at serine‐529 (AceCOX‐1), in blood platelets vs. colorectal mucosa, at 7 (group 1) and 24 h (group 2) after dosing. A significantly (P < 0.01) lower %AceCOX‐1 was detected in colonic and rectal mucosa (average 64%) vs. platelets (average 75%) in both groups. This effect was associated with an average 46% (P < 0.01) and 35% (P < 0.05) reduction in prostaglandin (PG) E2 levels and phosphorylated S6 (p‐S6) levels, respectively. Rectal mucosal levels of p‐S6/S6 significantly (P < 0.01) correlated with PGE2. These findings demonstrate that low‐dose aspirin produces long‐lasting acetylation of COX‐1 and downregulation of p‐S6 in human colorectal mucosa, an effect that may interfere with early colorectal carcinogenesis.

Medium-chain plasma acylcarnitines, ketone levels, cognition, and gray matter volumes in healthy elderly, mildly cognitively impaired, or Alzheimer's disease subjects

Aging, amyloid deposition, and tau-related pathology are key contributors to the onset and progression of Alzheimers disease (AD). However, AD is also associated with brain hypometabolism and deficits of mitochondrial bioenergetics. Plasma acylcarnitines (ACCs) are indirect indices of altered fatty acid beta-oxidation, and ketogenesis has been found to be decreased on aging. Furthermore, in elderly subjects, alterations in plasma levels of specific ACCs have been suggested to predict conversion to mild cognitive impairment (MCI) or AD. In this study, we assayed plasma profiles of ACCs in a cohort of healthy elderly control, MCI subjects, and AD patients. Compared with healthy controls or MCI subjects, AD patients showed significant lower plasma levels of several medium-chain ACCs. Furthermore, in AD patients, these lower concentrations were associated with lower prefrontal gray matter volumes and the presence of cognitive impairment. Interestingly, lower levels of medium-chain ACCs were also found to be associated with lower plasma levels of 2-hydroxybutyric acid. Overall, these findings suggest that altered metabolism of medium-chain ACCs and impaired ketogenesis can be metabolic features of AD.

Serum lipidomic study reveals potential early biomarkers for predicting response to chemoradiation therapy in advanced rectal cancer: A pilot study

Purpose Prospective detection of patients with advanced rectal cancer (LARC) who have a higher probability of responding to preoperative chemoradiotherapy (CRT) may provide individualized therapy. Lipidomics is an emerging science dedicated to the characterization of lipid fingerprint involved in different pato-physiological conditions. The purpose of this study is to highlight a typical lipid signature able to predict the tumor response to CRT. Experimental Design A prospective global analysis of lipids in 54 sera from 18 LARC patients treated with preoperative CRT was performed. Samples were collected at 3 time points: before (T0), at 14th day and at 28th day of CRT. An open LC-MS/MS analysis was performed to characterize lipid expression at T0. Differential lipids were validated by an independent approach and studied during treatment. Results From 65 differential lipids highlighted between responder (RP) vs not responder (NRP) patients, five lipids were validated to predict response at T0: SM(d18:2/18:1), LysoPC (16:0/0:0), LysoPC (15:1(9z)/0:0), Lyso PE (22:5/0:0) and m/z= 842.90 corresponding to a PC containing 2 fatty acids of 40 carbons totally. The levels of these lipids were lower in NRP before treatment. The ROC curve obtained by combining these five lipid signals showed an AUC of 0.95, evidence of good sensitivity and specificity in discriminating groups. Conclusion Our results are in agreement with previous evidences about the role of lipids in determining the tumor response to therapy and suggest that the study of serum lipid could represent a useful tool in prediction of CRT response and in personalizing treatment.

Proteomic and metabolomic characterization of streptozotocin-induced diabetic nephropathy in TIMP3-deficient mice

AbstractAimsThe tissue inhibitor of metalloproteinase TIMP3 is a stromal protein that restrains the activity of both protease and receptor in the extracellular matrix and has been found to be down-regulated in diabetic nephropathy (DN), the leading cause of end-stage renal disease in developed countries. MethodsIn order to gain deeper insights on the association of loss of TIMP3 and DN, we performed differential proteomic analysis of kidney and blood metabolic profiling of wild-type and Timp3-knockout mice before and after streptozotocin (STZ) treatment, widely used to induce insulin deficiency and hyperglycemia. ResultsKidney proteomic data and blood metabolic profiles suggest significant alterations of peroxisomal and mitochondrial fatty acids β-oxidation in Timp3-knockout mice compared to wild-type mice under basal condition. These alterations were exacerbated in response to STZ treatment.ConclusionsProteomic and metabolomic approaches showed that loss of TIMP3 alone or in combination with STZ treatment results in significant alterations of kidney lipid metabolism and peripheral acylcarnitine levels, supporting the idea that loss of TIMP3 may generate a phenotype more prone to DN.