One-carbon metabolism in cancer

Cells require one-carbon units for nucleotide synthesis, methylation and reductive metabolism, and these pathways support the high proliferative rate of cancer cells. As such, anti-folates, drugs that target one-carbon metabolism, have long been used in the treatment of cancer. Amino acids, such as serine are a major one-carbon source, and cancer cells are particularly susceptible to deprivation of one-carbon units by serine restriction or inhibition of de novo serine synthesis. Recent work has also begun to decipher the specific pathways and sub-cellular compartments that are important for one-carbon metabolism in cancer cells. In this review we summarise the historical understanding of one-carbon metabolism in cancer, describe the recent findings regarding the generation and usage of one-carbon units and explore possible future therapeutics that could exploit the dependency of cancer cells on one-carbon metabolism

Longitudinal copy number, whole exome and targeted deep sequencing of 'good risk' IGHV-mutated CLL patients with progressive disease

Disease progression in IGHV-M CLL with 'good-risk' cytogenetics is frequently associated with co-evolution of 'poor risk' driver mutations and DNA methylation changes.Drug resistance in IGHV-M CLL may be consequent upon the emergence of an IGHV-U cloneThe biological features of IGHV-M CLL responsible for disease progression are still poorly understood. We undertook a longitudinal study close to diagnosis, pre-treatment and post relapse in thirteen patients presenting with cMBL or Stage A disease and good risk biomarkers (IGHV-M genes, no del(17p) or del(11q) and low CD38 expression) who nevertheless developed progressive disease, of whom ten have required therapy. Using cytogenetics, FISH, genome-wide DNA methylation and copy number analysis together with whole exome, targeted deep- and Sanger sequencing, at diagnosis we identified mutations in established CLL driver genes in nine (69%), non-coding mutations (PAX5 enhancer region) in three, and genomic complexity in two patients. Branching evolutionary trajectories predominated (n=9/13), revealing intra-tumoural epi- and genetic heterogeneity and sub-clonal competition prior to therapy. Of the patients subsequently requiring treatment, two had sub-clonal TP53 mutations that would not be detected by standard methodologies, three qualified for the very-low risk category defined by integrated mutational and cytogenetic analysis and yet had established or putative driver mutations and one patient developed progressive, therapy-refractory disease associated with the emergence of an IGHV-U clone. These data suggest that extended genomic and immunogenetic screening may have clinical utility in patients with apparent good risk disease.Leukemia accepted article preview online, 05 February 2016. doi:10.1038/leu.2016.10

Distinction between peanut allergy and tolerance by characterization of B​ cell receptor repertoires

BACKGROUND: Specific IgE against a peanut 2S albumin (Ara h 2 or 6) is the best predictor of clinically relevant peanut sensitization. However, sIgE levels of peanut allergic and those of peanut sensitized but tolerant patients partly overlap, highlighting the need for improved diagnostics to prevent incorrect diagnosis and consequently unnecessary food restrictions. Thus, we sought to explore differences in V(D)J gene transcripts coding for peanut 2S albumin‐specific monoclonal antibodies (mAbs) from allergic and sensitized but tolerant donors. METHODS: 2S albumin‐binding B‐cells were single‐cell sorted from peripheral blood of peanut allergic (n=6) and tolerant (n=6) donors sensitized to Ara h2 and/or 6 (≥ 0.1 kU/l) and non‐atopic controls (n=5). h 2 and/or 6 (≥ 0.1 kU/l). Corresponding h heavy and light chain gene transcripts were heterologously expressed as mAbs and tested for specificity to native Ara h2 and 6. HCDR3 sequence motifs were identified by Levenshtein distances and hierarchically clustering. RESULTS: The frequency of 2S albumin‐binding B cells was increased in allergic (median: 0.01%) compared to tolerant (median: 0.006%) and non‐atopic donors (median: 0.0015%, p = 0.008). The majority of mAbs (74%, 29/39) bound specifically to Ara h 2 and/or 6. Non‐specific mAbs (9/10) were mainly derived from non‐atopic controls. In allergic donors, 89% of heavy chain gene transcripts consisted of VH3 family genes, compared with only 54% in sensitized but tolerant and 63% of non‐atopic donors. Additionally, certain HCDR3 sequence motifs were associated with allergy (n = 4) or tolerance (n = 3) upon hierarchical clustering of their Levenshtein distances. CONCLUSIONS: Peanut allergy is associated with dominant VH3 family gene usage and certain public antibody sequences (HCDR3 motifs)