Unbiased Lipidomic Profiling of Triple-Negative Breast Cancer Tissues Reveals the Association of Sphingomyelin Levels with Patient Disease-Free Survival.

The reprogramming of lipid metabolism is a hallmark of many cancers that has been shown to promote breast cancer progression. While several lipid signatures associated with breast cancer aggressiveness have been identified, a comprehensive lipidomic analysis specifically targeting the triple-negative subtype of breast cancer (TNBC) may be required to identify novel biomarkers and therapeutic targets for this most aggressive subtype of breast cancer that still lacks effective therapies. In this current study, our global LC-MS-based lipidomics platform was able to measure 684 named lipids across 15 lipid classes in 70 TNBC tumors.

Tobacco-Specific Carcinogens Induce Hypermethylation, DNA Adducts, and DNA Damage in Bladder Cancer.

Smoking is a major risk factor for the development of bladder cancer; however, the functional consequences of the carcinogens in tobacco smoke and bladder cancer-associated metabolic alterations remain poorly defined. We assessed the metabolic profiles in bladder cancer smokers and non-smokers and identified the key alterations in their metabolism. LC/MS and bioinformatic analysis were performed to determine the metabolome associated with bladder cancer smokers and were further validated in cell line models.

Catalytic Role of the Substrate Defines Specificity of Therapeutic l-Asparaginase.

Type II bacterial L-asparaginases (L-ASP) have played an important therapeutic role in cancer treatment for over four decades, yet their exact reaction mechanism remains elusive. L-ASP from Escherichia coli deamidates asparagine (Asn) and glutamine, with an ~10(4) higher specificity (kcat/Km) for asparagine despite only one methylene difference in length. Through a sensitive kinetic approach, we quantify competition among the substrates and interpret its clinical role.

Targeted metabolomic analysis of amino acid response to L-asparaginase in adherent cells.

L-asparaginase (L-ASP) is a therapeutic enzyme used clinically for the treatment of childhood acute lymphoblastic leukemia. L-ASP's anticancer activity is believed to be associated primarily with depletion of asparagine, but secondary glutaminase activity has also been implicated in its anticancer mechanism of action. To investigate the effects of L-ASP on amino acid metabolism, we have developed an LC-MS/MS metabolomics platform for high-throughput quantitation of 29 metabolites, including all 20 proteinogenic amino acids, 6 metabolically related amino acid derivatives (ornithine, citrulline, sarcosine, taurine, hypotaurine, and cystine), and 3 polyamines (putrescince, spermidine, and spermine) in adherent cultured cells.

An artifact in LC-MS/MS measurement of glutamine and glutamic acid: in-source cyclization to pyroglutamic acid.

Advances in metabolomics, particularly for research on cancer, have increased the demand for accurate, highly sensitive methods for measuring glutamine (Gln) and glutamic acid (Glu) in cell cultures and other biological samples. N-terminal Gln and Glu residues in proteins or peptides have been reported to cyclize to pyroglutamic acid (pGlu) during liquid chromatography (LC)-mass spectrometry (MS) analysis, but cyclization of free Gln and Glu to free pGlu during LC-MS analysis has not been well-characterized. Using an LC-MS/MS protocol that we developed to separate Gln, Glu, and pGlu, we found that free Gln and Glu cyclize to pGlu in the electrospray ionization source, revealing a previously uncharacterized artifact in metabolomic studies.

The glutaminase activity of L-asparaginase is not required for anticancer activity against ASNS-negative cells.

L-Asparaginase (L-ASP) is a key component of therapy for acute lymphoblastic leukemia. Its mechanism of action, however, is still poorly understood, in part because of its dual asparaginase and glutaminase activities. Here, we show that L-ASP's glutaminase activity is not always required for the enzyme's anticancer effect.

Measurement of DNA concentration as a normalization strategy for metabolomic data from adherent cell lines.

Metabolomics is a rapidly advancing field, and much of our understanding of the subject has come from research on cell lines. However, the results and interpretation of such studies depend on appropriate normalization of the data; ineffective or poorly chosen normalization methods can lead to frankly erroneous conclusions. That is a recurrent challenge because robust, reliable methods for normalization of data from cells have not been established.

LC/ESR/MS study of pH-dependent radical generation from 15-LOX-catalyzed DPA peroxidation.

Docosapentaenoic acid (DPA) is a unique fatty acid that exists in two isomeric forms (n-3 and n-6), which differ in their physiological behaviors. DPA can undergo free radical-mediated peroxidation via lipoxygenase (LOX). 15-LOX, one of the LOX isomers, has received much attention in cancer research because of its very different expression level in normal tissues compared to tumors and some bioactive fatty acid metabolites modulating the tumorigenic pathways in cancer.

Characterization of free radicals formed from COX-catalyzed DGLA peroxidation.

Like arachidonic acid (AA), dihomo-γ-linolenic acid (DGLA) is a 20-carbon ω-6 polyunsaturated fatty acid and a substrate of cyclooxygenase (COX). Through free radical reactions, COX metabolizes DGLA and AA to form well-known bioactive metabolites, namely, the 1 and 2 series of prostaglandins (PGs1 and PGs2), respectively. Unlike PGs2, which are viewed as proinflammatory, PGs1 possess anti-inflammatory and anticancer activities.

A combination study of spin-trapping, LC/ESR and LC/MS on carbon-centred radicals formed from lipoxygenase-catalysed peroxidation of eicosapentaenoic acid.

Increased evidence from animal and in vitro cellular research indicates that the metabolism of eicosapentaenoic acid (EPA) can inhibit carcinogenesis in many cancers. Free radical-mediated peroxidation is one of many possible mechanisms to which EPA's anti-cancer activity has been attributed. However, no direct evidence has been obtained for the formation of any EPA-derived radicals.