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Biology subjects

Dalsass, M.

Publications and source records attributed to Dalsass, M..

4 recordsLinked to original sources

Efficient and effective identification of cancer neoantigens from tumor only RNA-seq

The growing accessibility of sequencing experiments has significantly accelerated the development of personalized immunotherapies based on the identification of cancer neoantigens. Still, the prediction of neoantigens involves lengthy and inefficient protocols, requiring simultaneous analysis of sequencing data from paired tumor/normal exomes and tumor transcriptome, often resulting in a low success rate. To date, the feasibility of adopting a more efficient strategy has not been fully evaluated. To this end, we developed ENEO, a computational approach to detect cancer neoantigens using solely the tumor RNA-seq data while addressing the lack of matched control through a Bayesian probabilistic model. ENEO was assessed on TESLA benchmark dataset, reporting efficient identification of DNA-alterations derived neoantigens and compelling results against state-of-art exome-based methods. We further validated the method on two independent cohorts, encompassing different tumor types and experimental procedures. Our work demonstrates that a tumor-only RNA-based approach, such as the one implemented in ENEO, maintains accuracy in identifying mutated peptides resulting from expressed genomic alterations, while also broadening the pool of potential pMHCs with RNAspecific mutations in a faster and cost-effective way. ENEO is freely available at https://github.com/ctglab/ENEO

bioinformatics↗

Polycomb Group Ring Finger Protein 6 suppresses Myc-induced lymphomagenesis

Max is an obligate dimerization partner for the Myc transcription factors and for several repressors, such as Mnt, Mxd1-4 and Mga, collectively thought to antagonize Myc function in transcription and oncogenesis. Mga, in particular, is part of the variant Polycomb group repressive complex PRC1.6. Here, we show that ablation of the distinct PRC1.6 subunit Pcgf6 - but not Mga - accelerates Myc-induced lymphomagenesis in E{micro}-myc transgenic mice. Unexpectedly, however, Pcgf6 loss shows no significant impact on transcriptional profiles, in neither pre-tumoral B-cells, nor lymphomas. Altogether, these data unravel an unforeseen, Mga- and PRC1.6-independent tumor suppressor activity of Pcgf6.

cancer biology↗

Outer Membrane Vesicles from the gut microbiome contribute to tumor immunity by eliciting cross-reactive T cells

The gut microbiome plays a key role in cancer immunity. One proposed mechanism is through the elicitation of T cells, which incidentally recognize neo-epitopes arising from cancer mutations ("molecular mimicry (MM)" hypothesis). To support MM, Escherichia coli Nissle was engineered with the SIINFEKL epitope (OVA) and orally administered to C57BL/6 mice. The treatment elicited OVA-specific CD8+ T cells in the lamina propria and inhibited the growth of OVA-B16F10 tumors. Importantly, the administration of Outer Membrane Vesicles (OMVs) engineered with different T cell epitopes elicited epitope-specific T cells and inhibited tumor growth. Microbiome shotgun sequencing and TCR sequencing provided evidence that cross-reacting T cells were induced at the mucosal level and subsequently reached the tumor site. Overall, our data support the role of MM in tumor immunity, assign a new role to OMVs and pave the way to new probiotics/OMV-based anti-cancer immunotherapies.

microbiology↗

Integrated requirement of non-specific and sequence-specific DNA binding in MYC-driven transcription

Eukaryotic transcription factors recognize specific DNA sequence motifs, but are also endowed with generic, non-specific DNA-binding activity: how these binding modes are integrated to determine select transcriptional outputs remains unresolved. We designed mutants of the MYC transcription factor bearing substitutions in residues that contact either the DNA backbone or specific bases within the consensus binding motif (E-box), and profiled their DNA-binding and gene-regulatory activities in murine cells. Our data reveal that non-specific DNA binding is required for MYC to engage onto active regulatory elements in the genome, preceding sequence recognition; beyond merely stabilizing MYC onto select target loci, sequence-specific binding contributes to its precise positioning and - most unexpectedly - to transcriptional activation per se. In particular, at any given binding intensity, promoters targeted via the cognate DNA motif were more frequently activated by MYC. Hence, seemingly promiscuous chromatin interaction profiles actually encompass diverse DNA-binding modalities, driving defined, sequence-dependent transcriptional responses.

molecular biology↗