Omega-3 Fatty Acids DHA and EPA Reduce Bortezomib Resistance in Multiple Myeloma Cells by Promoting Glutathione Degradation.

Multiple myeloma (MM) is a hematological malignancy that exhibits aberrantly high levels of proteasome activity. While treatment with the proteasome inhibitor bortezomib substantially increases overall survival of MM patients, acquired drug resistance remains the main challenge for MM treatment. Using a combination treatment of docosahexaenoic acid (DHA) or eicosapentaenoic acid (EPA) and bortezomib, it was demonstrated previously that pretreatment with DHA/EPA significantly increased bortezomib chemosensitivity in MM cells. In the current study, both transcriptome and metabolome analysis were performed to comprehensively evaluate the underlying mechanism. It was demonstrated that pretreating MM cells with DHA/EPA before bortezomib potently decreased the cellular glutathione (GSH) level and altered the expression of the related metabolites and key enzymes in GSH metabolism, whereas simultaneous treatment only showed minor effects on these factors, thereby suggesting the critical role of GSH degradation in overcoming bortezomib resistance in MM cells. Moreover, RNA-seq results revealed that the nuclear factor erythroid 2-related factor 2 (NRF2)-activating transcription factor 3/4 (ATF3/4)-ChaC glutathione specific gamma-glutamylcyclotransferase 1 (CHAC1) signaling pathway may be implicated as the central player in the GSH degradation. Pathways of necroptosis, ferroptosis, p53, NRF2, ATF4, WNT, MAPK, NF-κB, EGFR, and ERK may be connected to the tumor suppressive effect caused by pretreatment of DHA/EPA prior to bortezomib. Collectively, this work implicates GSH degradation as a potential therapeutic target in MM and provides novel mechanistic insights into its significant role in combating bortezomib resistance.

Description of the EuroTARGET cohort: A European collaborative project on TArgeted therapy in renal cell cancer-GEnetic- and tumor-related biomarkers for response and toxicity.

OBJECTIVE: For patients with metastatic renal cell cancer (mRCC), treatment choice is mainly based on clinical parameters. With many treatments available and the limited response to treatment and associated toxicities, there is much interest in identifying better biomarkers for personalized treatment. EuroTARGET aims to identify and characterize host- and tumor-related biomarkers for prediction of response to tyrosine kinase inhibitor therapy in mRCC. Here, we describe the EuroTARGET mRCC patient cohort. METHODS AND MATERIALS: EuroTARGET is a European collaborative project designed as an observational study for which patients with mRCC were recruited prospectively in 62 centers. In addition, 462 patients with mRCC from previous studies were included. Detailed clinical information (baseline and follow-up) from all patients was entered in web-based case record forms. Blood was collected for germline DNA and pharmacokinetic/pharmacodynamic analyses and, where available, fresh-frozen tumor material was collected to perform tumor DNA, RNA, kinome, and methylome analyses. RESULTS: In total, 1,210 patients with mRCC were included. Of these, 920 received a tyrosine kinase inhibitor as first-line targeted treatment (sunitinib [N = 713, 78%], sorafenib [N = 41, 4%], or pazopanib [N = 166, 18%]) and had at least 6 months of outcome assessment (median follow-up 15.3 months [interquartile range: 8.5-30.2 months]). Germline DNA samples were available from 824 of these patients, fresh-frozen tumor material from 142 patients, fresh-frozen normal kidney tissue from 95 patients, and tissue microarrays created from formalin-fixed paraffin-embedded tumor material from 247 patients. Of the 920 patients, germline DNA variant chip data were successfully generated for 811 patients (Illumina HumanOmniExpress BeadChip). For 80 patients, next-generation exome sequencing of germline and tumor DNA was performed, tumor RNA sequencing was performed for 124 patients, kinome activity measured and processed for 121 patients (PamChip), and methylome data (Illumina Infinium HumanMethylation450 BeadChip) were created for 116 RCC tissues (and 23 normal kidney tissues). For 73 out of the 920 patients, all platform data types were generated. In addition, 40 patients were included in a pharmacokinetic/pharmacodynamic phase IV substudy. CONCLUSIONS: Analysis of EuroTARGET cohort data will contribute to personalization of therapy for patients with mRCC. The extensive clinical data and multiplatform EuroTARGET data will be freely available.

Development of a microarray detection method for galectin cancer proteins based on ligand binding.

In this article, we describe the development of a novel detection method for the visualization of ligand-binding proteins. Current proteomic tools, such as the enzyme-linked immunosorbent assay (ELISA), are based on protein abundance rather than protein activity and can result in conflicting data. To address this issue, we developed an assay in which ligand binding is detected using a microarray approach with immobilized antibodies on a porous aluminum oxide matrix. The galectin family of proteins was used as a model system to evaluate the performance of this approach. Galectins selectively bind galactosides and are linked to cancer progression. Our assay employed antibodies directed against different galectins. The antibodies were immobilized on the microarray surface by use of protein A/G. In our example, galectin-1 and galectin-9 were then detected in cell lysates. Lysates were exposed to the anti-galectin surface, followed by washing and quantification with a general fluorescent galectin ligand. The optimal galectin ligand allowed detection of nanogram amounts of galectin using only 1 µg of antibody. Galectin-1 was visualized in HeLa and tumor cell lysates, indicating the potential of the method for a clinical setting.

Multivalent carbohydrate recognition on a glycodendrimer-functionalized flow-through chip.

Dendrimers were fitted out with up to eight mannose moieties by "click" chemistry. They were subsequently attached to aluminum oxide chips via a spacer that was linked to the dendrimer core; this resulted in a microarray of glycodendrimers. Binding of the glycodendrimers to the fluorescent lectins ConA and GNA was observable in real time. In a single experiment it was possible to observe the multivalency enhancement or cluster effect in the binding event. This effect was small for ConA, in agreement with its widely spaced binding sites, whereas it was large for GNA, with its twelve much more closely spaced binding sites. The dendrimer-fitted chip represents a valuable screening tool for multivalency effects. Furthermore kinetic and thermodynamic data on binding events can be deduced. Inhibition experiments are also possible with the system as was shown for ConA with alpha-methyl mannose as the inhibitor.