Diffuse large B-cell lymphoma (DLBCL) is the most frequent lymphoid malignancy affecting adults. NF-kB transcription factor family is activated by two main pathways, the canonical and the alternative NF-kB activation pathways with different functions. The alternative NF-kB pathway leads to the activation of the transcriptionally active RelB NF-kB subunit. Alternative NF-kB activation status and its role in DLBCL pathogenesis remain undefined. Here, we reveal a frequent activation of RelB in a large cohort of DLBCL patients and cell lines, independently of their ABC or GCB subtypes. RelB activity defines a new subset of DLBCL patients with a peculiar gene expression profile and mutational pattern. Importantly, RelB activation does not correlate with the MCD genetic subtype, enriched for ABC tumors carrying MYD88L265P and CD79B mutations that cooperatively activate canonical NF-kB, thus indicating that current genetic tools to evaluate NF-kB activity in DLBCL do not provide information on the alternative NF-kB activation. Further, the newly defined RelB-positive subgroup of DLBCL patients exhibits a dismal outcome following immunochemotherapy. Functional studies revealed that RelB confers DLBCL cell resistance to DNA-damage induced apoptosis in response to doxorubicin, a genotoxic agent used in front-line treatment for DLBCL. We also show that RelB positivity is associated with high expression of cIAP2. Altogether, RelB activation can be used to refine the prognostic stratification of DLBCL and may contribute to subvert the therapeutic DNA damage response in a segment of DLBCL patients.

No abstract

Accurate quantification of metabolites by nuclear magnetic resonance (NMR) is of prime importance in the field of health sciences for understanding the metabolic pathways of the investigated system, to address the mechanisms of action of diseases, and improving their diagnosis, treatment, and prognosis. Unfortunately, the absolute quantitative analysis of complex samples is still limited by sensitivity and resolution issues that are intrinsic to this technique. Ultrahigh-resolution pure shift methods have especially shown to be suitable for interpreting mixtures of metabolites in biological samples. Here, we introduce a robust analytical protocol based on the use of a pure shift library of calibration reference spectra to fit the fingerprint of each metabolite of interest and determine its concentration. The approach based on the SAPPHIRE pulse sequence enhanced with a block for solvent suppression has been validated through the results of a series of model mixtures, exhibiting excellent trueness (slope values in the range of 0.93–1.02) and linearity (R 2 > 0.996) in a total time (a few hours) that is fully compatible with metabolomics studies. Furthermore, we have successfully applied our method to determine the absolute metabolite concentrations in a lymphoma extracellular medium, which improves metabolomic protocols reported to date by providing a quantitative and highly resolved vision of metabolic processes at play.

Cancer cells outgrowing in distant organs of metastasis rewire their metabolism to fuel on the available nutrients. While this is often considered an adaptive pressure limiting metastasis formation, some nutrients available at the metastatic site naturally or through changes in organ physiology may inherently promote metastatic growth. We find that the lung, a frequent site of metastasis, is a lipid-rich environment. Moreover, we observe that pathological conditions such as pre-metastatic niche formation and obesity further increase the availability of the fatty acid palmitate in the lung. We find that targeting palmitate processing inhibits spheroid growth in vitro and metastasis formation in lean and obese mice. Mechanistically, we discover that breast cancer cells use palmitate to synthesize acetyl-CoA in a carnitine palmitoyltransferase 1a (CPT1a)-dependent manner. Lysine acetyltransferase 2a (KAT2a), whose expression is promoted by palmitate availability, relies on the available acetyl-CoA to acetylate the NF-kB subunit p65. This favors nuclear location of p65 and activates a pro-metastatic transcriptional program. Accordingly, deletion of KAT2a phenocopies CPT1a silencing in vitro as well as in vivo and patients with breast cancer show co-expression of both proteins in metastases across palmitate-rich metastatic sites. In conclusion, we find that palmitate-rich environments foster metastasis growth by increasing p65 acetylation resulting in elevated NF-kB signaling.

N/A

Glutamine is under scrutiny regarding its metabolic deregulation linked to energetic reprogramming in cancer cells. Many analytical techniques have been used to better understand the impact of the metabolism of amino acids on biological processes, however only a few are suited to work with complex samples. Here, we report the use of a general dissolution dynamic nuclear polarization (D‐DNP) formulation using an unexpensive radical as a multipurpose tool to study glutamine, with insights from enzymatic modelling to complex metabolic networks and fast imaging. First, hyperpolarized [5‐13C] glutamine is used as molecular probe to study the kinetic action of two enzymes: L‐asparaginase that has been used as an anti‐metabolic treatment for cancer, and glutaminase. These results are also compared with those acquired with another hyperpolarized amino acid, [1,4‐13C] asparagine. Second, we explored the use of hyperpolarized (HP) substrates to probe metabolic pathways by monitoring metabolic profiles arising from hyperpolarized glutamine in E. coli extracts. Finally, a highly concentrated sample formulation is proposed for the purpose of fast imaging applications. We think that this approach can be extended to formulate other amino acids as well as other metabolites and provide complementary insights into the analysis of metabolic networks.