Tissue-resident FOLR2+ macrophages associate with CD8+ T cell infiltration in human breast cancer.

Macrophage infiltration is a hallmark of solid cancers, and overall macrophage infiltration correlates with lower patient survival and resistance to therapy. Tumor-associated macrophages, however, are phenotypically and functionally heterogeneous. Specific subsets of tumor-associated macrophage might be endowed with distinct roles on cancer progression and antitumor immunity. Here, we identify a discrete population of FOLR2+ tissue-resident macrophages in healthy mammary gland and breast cancer primary tumors. FOLR2+ macrophages localize in perivascular areas in the tumor stroma, where they interact with CD8+ T cells. FOLR2+ macrophages efficiently prime effector CD8+ T cells ex vivo. The density of FOLR2+ macrophages in tumors positively correlates with better patient survival. This study highlights specific roles for tumor-associated macrophage subsets and paves the way for subset-targeted therapeutic interventions in macrophages-based cancer therapies.

Macrophages Maintain Epithelium Integrity by Limiting Fungal Product Absorption.

The colon is primarily responsible for absorbing fluids. It contains a large number of microorganisms including fungi, which are enriched in its distal segment. The colonic mucosa must therefore tightly regulate fluid influx to control absorption of fungal metabolites, which can be toxic to epithelial cells and lead to barrier dysfunction. How this is achieved remains unknown. Here, we describe a mechanism by which the innate immune system allows rapid quality check of absorbed fluids to avoid intoxication of colonocytes. This mechanism relies on a population of distal colon macrophages that are equipped with "balloon-like" protrusions (BLPs) inserted in the epithelium, which sample absorbed fluids. In the absence of macrophages or BLPs, epithelial cells keep absorbing fluids containing fungal products, leading to their death and subsequent loss of epithelial barrier integrity. These results reveal an unexpected and essential role of macrophages in the maintenance of colon-microbiota interactions in homeostasis. VIDEO ABSTRACT.

Epithelial colonization by gut dendritic cells promotes their functional diversification.

Dendritic cells (DCs) patrol tissues and transport antigens to lymph nodes to initiate adaptive immune responses. Within tissues, DCs constitute a complex cell population composed of distinct subsets that can exhibit different activation states and functions. How tissue-specific cues orchestrate DC diversification remains elusive. Here, we show that the small intestine included two pools of cDC2s originating from common pre-DC precursors: (1) lamina propria (LP) CD103+CD11b+ cDC2s that were mature-like proinflammatory cells and (2) intraepithelial cDC2s that exhibited an immature-like phenotype as well as tolerogenic properties. These phenotypes resulted from the action of food-derived retinoic acid (ATRA), which enhanced actomyosin contractility and promoted LP cDC2 transmigration into the epithelium. There, cDC2s were imprinted by environmental cues, including ATRA itself and the mucus component Muc2. Hence, by reaching distinct subtissular niches, DCs can exist as immature and mature cells within the same tissue, revealing an additional mechanism of DC functional diversification.

Follicular lymphoma triggers phenotypic and functional remodeling of the human lymphoid stromal cell landscape.

Lymphoid stromal cells (LSCs) are essential organizers of immune responses. We analyzed tonsillar tissue by combining flow cytometry, in situ imaging, RNA sequencing, and functional assays, defining three distinct human LSC subsets. The integrin CD49a designated perivascular stromal cells exhibiting features of local committed LSC precursors and segregated cytokine and chemokine-producing fibroblastic reticular cells (FRCs) supporting B and T cell survival. The follicular dendritic cell transcriptional profile reflected active responses to B cell and non-B cell stimuli. We therefore examined the effect of B cell stimuli on LSCs in follicular lymphoma (FL). FL B cells interacted primarily with CD49a+ FRCs. Transcriptional analyses revealed LSC reprogramming in situ downstream of the cytokines tumor necrosis factor (TNF) and transforming growth factor ß (TGF-ß), including increased expression of the chemokines CCL19 and CCL21. Our findings define human LSC populations in healthy tissue and reveal bidirectional crosstalk between LSCs and malignant B cells that may present a targetable axis in lymphoma.

Oncogenic chimeric transcription factors drive tumor-specific transcription, processing, and translation of silent genomic regions.

Many cancers are characterized by gene fusions encoding oncogenic chimeric transcription factors (TFs) such as EWS::FLI1 in Ewing sarcoma (EwS). Here, we find that EWS::FLI1 induces the robust expression of a specific set of novel spliced and polyadenylated transcripts within otherwise transcriptionally silent regions of the genome. These neogenes (NGs) are virtually undetectable in large collections of normal tissues or non-EwS tumors and can be silenced by CRISPR interference at regulatory EWS::FLI1-bound microsatellites. Ribosome profiling and proteomics further show that some NGs are translated into highly EwS-specific peptides. More generally, we show that hundreds of NGs can be detected in diverse cancers characterized by chimeric TFs. Altogether, this study identifies the transcription, processing, and translation of novel, specific, highly expressed multi-exonic transcripts from otherwise silent regions of the genome as a new activity of aberrant TFs in cancer.

A druggable copper-signalling pathway that drives inflammation.

Inflammation is a complex physiological process triggered in response to harmful stimuli1. It involves cells of the immune system capable of clearing sources of injury and damaged tissues. Excessive inflammation can occur as a result of infection and is a hallmark of several diseases2-4. The molecular bases underlying inflammatory responses are not fully understood. Here we show that the cell surface glycoprotein CD44, which marks the acquisition of distinct cell phenotypes in the context of development, immunity and cancer progression, mediates the uptake of metals including copper. We identify a pool of chemically reactive copper(II) in mitochondria of inflammatory macrophages that catalyses NAD(H) redox cycling by activating hydrogen peroxide. Maintenance of NAD+ enables metabolic and epigenetic programming towards the inflammatory state. Targeting mitochondrial copper(II) with supformin (LCC-12), a rationally designed dimer of metformin, induces a reduction of the NAD(H) pool, leading to metabolic and epigenetic states that oppose macrophage activation. LCC-12 interferes with cell plasticity in other settings and reduces inflammation in mouse models of bacterial and viral infections. Our work highlights the central role of copper as a regulator of cell plasticity and unveils a therapeutic strategy based on metabolic reprogramming and the control of epigenetic cell states.

A Conserved Noncoding Locus Regulates Random Monoallelic Xist Expression across a Topological Boundary.

cis-Regulatory communication is crucial in mammalian development and is thought to be restricted by the spatial partitioning of the genome in topologically associating domains (TADs). Here, we discovered that the Xist locus is regulated by sequences in the neighboring TAD. In particular, the promoter of the noncoding RNA Linx (LinxP) acts as a long-range silencer and influences the choice of X chromosome to be inactivated. This is independent of Linx transcription and independent of any effect on Tsix, the antisense regulator of Xist that shares the same TAD as Linx. Unlike Tsix, LinxP is well conserved across mammals, suggesting an ancestral mechanism for random monoallelic Xist regulation. When introduced in the same TAD as Xist, LinxP switches from a silencer to an enhancer. Our study uncovers an unsuspected regulatory axis for X chromosome inactivation and a class of cis-regulatory effects that may exploit TAD partitioning to modulate developmental decisions.

Targeted long-read sequencing of the Ewing sarcoma 6p25.1 susceptibility locus identifies germline-somatic interactions with EWSR1-FLI1 binding.

Ewing sarcoma (EwS) is a rare bone and soft tissue malignancy driven by chromosomal translocations encoding chimeric transcription factors, such as EWSR1-FLI1, that bind GGAA motifs forming novel enhancers that alter nearby expression. We propose that germline microsatellite variation at the 6p25.1 EwS susceptibility locus could impact downstream gene expression and EwS biology. We performed targeted long-read sequencing of EwS blood DNA to characterize variation and genomic features important for EWSR1-FLI1 binding. We identified 50 microsatellite alleles at 6p25.1 and observed that EwS-affected individuals had longer alleles (>135 bp) with more GGAA repeats. The 6p25.1 GGAA microsatellite showed chromatin features of an EWSR1-FLI1 enhancer and regulated expression of RREB1, a transcription factor associated with RAS/MAPK signaling. RREB1 knockdown reduced proliferation and clonogenic potential and reduced expression of cell cycle and DNA replication genes. Our integrative analysis at 6p25.1 details increased binding of longer GGAA microsatellite alleles with acquired EWSR-FLI1 to promote Ewing sarcomagenesis by RREB1-mediated proliferation.

Aryl Hydrocarbon Receptor Controls Monocyte Differentiation into Dendritic Cells versus Macrophages.

After entering tissues, monocytes differentiate into cells that share functional features with either macrophages or dendritic cells (DCs). How monocyte fate is directed toward monocyte-derived macrophages (mo-Macs) or monocyte-derived DCs (mo-DCs) and which transcription factors control these differentiation pathways remains unknown. Using an in vitro culture model yielding human mo-DCs and mo-Macs closely resembling those found in vivo in ascites, we show that IRF4 and MAFB were critical regulators of monocyte differentiation into mo-DCs and mo-Macs, respectively. Activation of the aryl hydrocarbon receptor (AHR) promoted mo-DC differentiation through the induction of BLIMP-1, while impairing differentiation into mo-Macs. AhR deficiency also impaired the in vivo differentiation of mouse mo-DCs. Finally, AHR activation correlated with mo-DC infiltration in leprosy lesions. These results establish that mo-DCs and mo-Macs are controlled by distinct transcription factors and show that AHR acts as a molecular switch for monocyte fate specification in response to micro-environmental factors.

Enrichment of centromeric DNA from human cells.

Centromeres are key elements for chromosome segregation. Canonical centromeres are built over long-stretches of tandem repetitive arrays. Despite being quite abundant compared to other loci, centromere sequences overall still represent only 2 to 5% of the human genome, therefore studying their genetic and epigenetic features is a major challenge. Furthermore, sequencing of centromeric regions requires high coverage to fully analyze length and sequence variations, and this can be extremely costly. To bypass these issues, we have developed a technique, named CenRICH, to enrich for centromeric DNA from human cells based on selective restriction digestion and size fractionation. Combining restriction enzymes cutting at high frequency throughout the genome, except within most human centromeres, with size-selection of fragments >20 kb, resulted in over 25-fold enrichment in centromeric DNA. High-throughput sequencing revealed that up to 60% of the DNA in the enriched samples is made of centromeric repeats. We show that this method can be used in combination with long-read sequencing to investigate the DNA methylation status of certain centromeres and, with a specific enzyme combination, also of their surrounding regions (mainly HSATII). Finally, we show that CenRICH facilitates single-molecule analysis of replicating centromeric fibers by DNA combing. This approach has great potential for making sequencing of centromeric DNA more affordable and efficient and for single DNA molecule studies.

Acyl-coenzyme a binding protein (ACBP) - a risk factor for cancer diagnosis and an inhibitor of immunosurveillance.

BACKGROUND: The plasma concentrations of acyl coenzyme A binding protein (ACBP, also known as diazepam-binding inhibitor, DBI, or 'endozepine') increase with age and obesity, two parameters that are also amongst the most important risk factors for cancer. METHODS: We measured ACBP/DBI in the plasma from cancer-free individuals, high-risk patients like the carriers of TP53 or BRCA1/2 mutations, and non-syndromic healthy subjects who later developed cancer. In mice, the neutralization of ACBP/DBI was used in models of non-small cell lung cancer (NSCLC) and breast cancer development and as a combination treatment with chemoimmunotherapy (chemotherapy + PD-1 blockade) in the context of NSCLC and sarcomas. The anticancer T cell response upon ACBP/DBI neutralization was characterized by flow cytometry and single-cell RNA sequencing. RESULTS: Circulating levels of ACBP/DBI were higher in patients with genetic cancer predisposition (BRCA1/2 or TP53 germline mutations) than in matched controls. In non-syndromic cases, high ACBP/DBI levels were predictive of future cancer development, and especially elevated in patients who later developed lung cancer. In preclinical models, ACBP/DBI neutralization slowed down breast cancer and NSCLC development and enhanced the efficacy of chemoimmunotherapy in NSCLC and sarcoma models. When combined with chemoimmunotherapy, the neutralizing monoclonal antibody against ACBP/DBI reduced the frequency of regulatory T cells in the tumor bed, modulated the immune checkpoint profile, and increased activation markers. CONCLUSION: These findings suggest that ACBP/DBI acts as an endogenous immune suppressor. We conclude that elevation of ACBP/DBI constitutes a risk factor for the development of cancer and that ACBP/DBI is an actionable target for improving cancer immunosurveillance.

Methylation, Gene Expression, and Risk Genotypes at the TERT-CLPTM1L Locus in Cervical Cancer.

The reverse transcriptase subunit of telomerase, TERT, is frequently activated in high-grade dysplasia and invasive cancers of the uterine cervix. Telomerase activation through hypomethylation of the TERT promoter holds promise as a biomarker for cervical cancer progression, however, specific CpG sites involved in cervical cancer risk remain to be fully defined. A recent genome-wide association study on cervical cancer identified genetic polymorphisms at 5p13.33 (close to TERT-CLPTM1L) but the underlying mechanisms are undetermined. We investigated 529 CpG sites within the TERT promoter region and 3 CpG islands nearby, and 21 CpG sites within CLPTM1L in 190 bisulfite-converted cervical tumor DNA samples from BioRAIDs (NCT02428842). We identified eight CpG sites within TERT intron 2 where methylation was significantly associated with the genotypes of cervical cancer risk variants rs27070 and rs459961 in cervical tumors after multiple testing correction (p < 9.4 × 10E-5). Hypermethylation at chr5:1289663 correlated with decreased TERT mRNA levels. In an independent series of 188 normal or dysplastic cervical tissues, rare alleles of rs27070 and rs459961 were associated with low basal CLPTM1L levels and with the absence of TERT mRNA in HPV-negative samples, consistent with their proposed role as protective variants for cervical cancer. HPV infection was associated with increased CLPTM1L and TERT levels. Collectively, our results provide a link between cervical cancer risk variants, methylation, and gene expression and implicate both TERT and CLPTM1L as genes modulated by genomic background and HPV infection during cervical cancer development.

Progression-associated molecular changes in basal/squamous and sarcomatoid bladder carcinogenesis.

The aggressive basal/squamous (Ba/Sq) bladder cancer (BLCA) subtype is often diagnosed at the muscle-invasive stage and can progress to the sarcomatoid variant. Identification of molecular changes occurring during progression from non-muscle-invasive BLCA (NMIBC) to Ba/Sq muscle-invasive BLCA (MIBC) is thus challenging in human disease. We used the N-butyl-N-(4-hydroxybutyl)-nitrosamine (BBN) mouse model of Ba/Sq MIBC to study longitudinally the molecular changes leading to the Ba/Sq phenotype and to the sarcomatoid variant using IHC and microdissection followed by RNA-seq at all stages of progression. A shift to the Ba/Sq phenotype started in early progression stages. Pathway analysis of gene clusters with coordinated expression changes revealed Shh signaling loss and a shift from fatty acid metabolism to glycolysis. An upregulated cluster, appearing early in carcinogenesis, showed relevance to human disease, identifying NMIBC patients at risk of progression. Similar to the human counterpart, sarcomatoid BBN tumors displayed a Ba/Sq phenotype and epithelial-mesenchymal transition (EMT) features. An EGFR/FGFR1 signaling switch occurred with sarcomatoid dedifferentiation and correlated with EMT. BLCA cell lines with high EMT were the most sensitive to FGFR1 knockout and resistant to EGFR knockout. Taken together, these findings provide insights into the underlying biology of Ba/Sq BLCA progression and sarcomatoid dedifferentiation with potential clinical implications. © 2023 The Authors. The Journal of Pathology published by John Wiley & Sons Ltd on behalf of The Pathological Society of Great Britain and Ireland.

Artificial intelligence-based pathology as a biomarker of sensitivity to atezolizumab-bevacizumab in patients with hepatocellular carcinoma: a multicentre retrospective study.

BACKGROUND: Clinical benefits of atezolizumab plus bevacizumab (atezolizumab-bevacizumab) are observed only in a subset of patients with hepatocellular carcinoma and the development of biomarkers is needed to improve therapeutic strategies. The atezolizumab-bevacizumab response signature (ABRS), assessed by molecular biology profiling techniques, has been shown to be associated with progression-free survival after treatment initiation. The primary objective of our study was to develop an artificial intelligence (AI) model able to estimate ABRS expression directly from histological slides, and to evaluate if model predictions were associated with progression-free survival. METHODS: In this multicentre retrospective study, we developed a model (ABRS-prediction; ABRS-P), which was derived from the previously published clustering-constrained attention multiple instance learning (or CLAM) pipeline. We trained the model fit for regression analysis using a multicentre dataset from The Cancer Genome Atlas (patients treated by surgical resection, n=336). The ABRS-P model was externally validated on two independent series of samples from patients with hepatocellular carcinoma (a surgical resection series, n=225; and a biopsy series, n=157). The predictive value of the model was further tested in a series of biopsy samples from a multicentre cohort of patients with hepatocellular carcinoma treated with atezolizumab-bevacizumab (n=122). All samples in the study were from adults (aged ≥18 years). The validation sets were sampled between Jan 1, 2008, to Jan 1, 2023. For the multicentre validation set, the primary objective was to assess the association of high versus low ABRS-P values, defined relative to cross-validation median split thresholds in the first biopsy series, with progression-free survival after treatment initiation. Finally, we performed spatial transcriptomics and matched prediction heatmaps with in situ expression profiles. FINDINGS: Of the 840 patients sampled, 641 (76%) were male and 199 (24%) were female. Across the development and validation datasets, hepatocellular carcinoma risk factors included alcohol intake, hepatitis B and C virus infections, and non-alcoholic steatohepatitis. Using cross-validation in the development series, the mean Pearson's correlation between ABRS-P values and ABRS score (mean expression of ABRS genes) was r=0·62 (SD 0·09; mean p<0·0001, SD<0·0001). The ABRS-P generalised well on the external validation series (surgical resection series, r=0·60 [95% CI 0·51-0·68], p<0·0001; biopsy series, r=0·53 [0·40-0·63], p<0·0001). In the 122 patients treated with atezolizumab-bevacizumab, those with ABRS-P-high tumours (n=74) showed significantly longer median progression-free survival than those with ABRS-P-low tumours (n=48) after treatment initiation (12 months [95% CI 7-not reached] vs 7 months [4-9]; p=0·014). Spatial transcriptomics showed significantly higher ABRS score, along with upregulation of various other immune effectors, in tumour areas with high ABRS-P values versus areas with low ABRS-P values. INTERPRETATION: Our study indicates that AI applied on hepatocellular carcinoma digital slides is able to serve as a biomarker for progression-free survival in patients treated with atezolizumab-bevacizumab. This approach could be used in the development of inexpensive and fast biomarkers for targeted therapies. The combination of AI heatmaps with spatial transcriptomics provides insight on the molecular features associated with predictions. This methodology could be applied to other cancers or diseases and improve understanding of the biological mechanisms that drive responses to treatments. FUNDING: Institut National du Cancer, Fondation ARC, China Scholarship Council, Ligue Contre le Cancer du Val de Marne, Fondation de l'Avenir, Ipsen, and Fondation Bristol Myers Squibb Pour la Recherche en Immuno-Oncologie.

Laminin-binding integrins are essential for the maintenance of functional mammary secretory epithelium in lactation.

Integrin dimers α3/ß1, α6/ß1 and α6/ß4 are the mammary epithelial cell receptors for laminins, which are major components of the mammary basement membrane. The roles of specific basement membrane components and their integrin receptors in the regulation of functional gland development have not been analyzed in detail. To investigate the functions of laminin-binding integrins, we obtained mutant mice with mammary luminal cell-specific deficiencies of the α3 and α6 integrin chains generated using the Cre-Lox approach. During pregnancy, mutant mice displayed decreased luminal progenitor activity and retarded lobulo-alveolar development. Mammary glands appeared functional at the onset of lactation in mutant mice; however, myoepithelial cell morphology was markedly altered, suggesting cellular compensation mechanisms involving cytoskeleton reorganization. Notably, lactation was not sustained in mutant females, and the glands underwent precocious involution. Inactivation of the p53 gene rescued the growth defects but did not restore lactogenesis in mutant mice. These results suggest that the p53 pathway is involved in the control of mammary cell proliferation and survival downstream of laminin-binding integrins, and underline an essential role of cell interactions with laminin for lactogenic differentiation.

Molecular characterisation of tumours of the lacrimal apparatus.

AIMS: Malignant tumours of the lacrimal apparatus are rare and frequently show a poor prognosis, with no clear therapeutic standards. Characterisation of the genetic landscape of these rare tumours is sparse, and therefore therapeutics generally follow those of their common salivary gland counterparts. To further clarify the pathophysiology and discover potential therapeutic targets, we investigated the genetic landscape of eight tumours of the lacrimal apparatus. METHODS AND RESULTS: DNA and RNA sequencing were performed to identify genetic mutations and gene fusions. Immunohistochemistry, fluorescence in-situ hybridisation and reverse transcription-polymerase chain reaction followed by Sanger sequencing were performed to confirm the identified molecular alterations. Genetic alterations were detected in six tumours. Among five adenoid cystic carcinomas (ACC), four had confirmed alterations of MYB or MYBL1 genes, including a MYB::NFIB fusion, a MYBL1::NFIB fusion, a MYB amplification and a novel NFIB::THSD7B fusion. Mutations in genes encoding epigenetic modifiers, as well as NOTCH1, FGFR2 and ATM mutations, were also identified in ACCs. A carcinoma ex pleomorphic adenoma showed TP53 and CIC mutations and an amplification of ERBB2. A transitional cell carcinoma was associated with HPV16 infection. No genetic alteration was found for one adenocarcinoma, not otherwise specified. CONCLUSIONS: Our study highlights the variety of molecular alterations associated with lacrimal system tumours and emphasises the importance of molecular testing in these tumours, which can reveal potentially targetable mutations. Our results also reinforce the hypothesis of a common physiopathology of all ACCs, regardless of their primary location.

ERG transcription factors have a splicing regulatory function involving RBFOX2 that is altered in the EWS-FLI1 oncogenic fusion.

ERG family proteins (ERG, FLI1 and FEV) are a subfamily of ETS transcription factors with key roles in physiology and development. In Ewing sarcoma, the oncogenic fusion protein EWS-FLI1 regulates both transcription and alternative splicing of pre-messenger RNAs. However, whether wild-type ERG family proteins might regulate splicing is unknown. Here, we show that wild-type ERG proteins associate with spliceosomal components, are found on nascent RNAs, and induce alternative splicing when recruited onto a reporter minigene. Transcriptomic analysis revealed that ERG and FLI1 regulate large numbers of alternative spliced exons (ASEs) enriched with RBFOX2 motifs and co-regulated by this splicing factor. ERG and FLI1 are associated with RBFOX2 via their conserved carboxy-terminal domain, which is present in EWS-FLI1. Accordingly, EWS-FLI1 is also associated with RBFOX2 and regulates ASEs enriched in RBFOX2 motifs. However, in contrast to wild-type ERG and FLI1, EWS-FLI1 often antagonizes RBFOX2 effects on exon inclusion. In particular, EWS-FLI1 reduces RBFOX2 binding to the ADD3 pre-mRNA, thus increasing its long isoform, which represses the mesenchymal phenotype of Ewing sarcoma cells. Our findings reveal a RBFOX2-mediated splicing regulatory function of wild-type ERG family proteins, that is altered in EWS-FLI1 and contributes to the Ewing sarcoma cell phenotype.

Trajectory and uniqueness of mutational signatures in yeast mutators.

The acquisition of mutations plays critical roles in adaptation, evolution, senescence, and tumorigenesis. Massive genome sequencing has allowed extraction of specific features of many mutational landscapes but it remains difficult to retrospectively determine the mechanistic origin(s), selective forces, and trajectories of transient or persistent mutations and genome rearrangements. Here, we conducted a prospective reciprocal approach to inactivate 13 single or multiple evolutionary conserved genes involved in distinct genome maintenance processes and characterize de novo mutations in 274 diploid Saccharomyces cerevisiae mutation accumulation lines. This approach revealed the diversity, complexity, and ultimate uniqueness of mutational landscapes, differently composed of base substitutions, small insertions/deletions (InDels), structural variants, and/or ploidy variations. Several landscapes parallel the repertoire of mutational signatures in human cancers while others are either novel or composites of subsignatures resulting from distinct DNA damage lesions. Notably, the increase of base substitutions in the homologous recombination-deficient Rad51 mutant, specifically dependent on the Polζ translesion polymerase, yields COSMIC signature 3 observed in BRCA1/BRCA2-mutant breast cancer tumors. Furthermore, "mutome" analyses in highly polymorphic diploids and single-cell bottleneck lineages revealed a diverse spectrum of loss-of-heterozygosity (LOH) signatures characterized by interstitial and terminal chromosomal events resulting from interhomolog mitotic cross-overs. Following the appearance of heterozygous mutations, the strong stimulation of LOHs in the rad27/FEN1 and tsa1/PRDX1 backgrounds leads to fixation of homozygous mutations or their loss along the lineage. Overall, these mutomes and their trajectories provide a mechanistic framework to understand the origin and dynamics of genome variations that accumulate during clonal evolution.

Human papilloma virus (HPV) integration signature in Cervical Cancer: identification of MACROD2 gene as HPV hot spot integration site.

BACKGROUND: Cervical cancer (CC) remains a leading cause of gynaecological cancer-related mortality with infection by human papilloma virus (HPV) being the most important risk factor. We analysed the association between different viral integration signatures, clinical parameters and outcome in pre-treated CCs. METHODS: Different integration signatures were identified using HPV double capture followed by next-generation sequencing (NGS) in 272 CC patients from the BioRAIDs study [NCT02428842]. Correlations between HPV integration signatures and clinical, biological and molecular features were assessed. RESULTS: Episomal HPV was much less frequent in CC as compared to anal carcinoma (p < 0.0001). We identified >300 different HPV-chromosomal junctions (inter- or intra-genic). The most frequent integration site in CC was in MACROD2 gene followed by MIPOL1/TTC6 and TP63. HPV integration signatures were not associated with histological subtype, FIGO staging, treatment or PFS. HPVs were more frequently episomal in PIK3CA mutated tumours (p = 0.023). Viral integration type was dependent on HPV genotype (p < 0.0001); HPV18 and HPV45 being always integrated. High HPV copy number was associated with longer PFS (p = 0.011). CONCLUSIONS: This is to our knowledge the first study assessing the prognostic value of HPV integration in a prospectively annotated CC cohort, which detects a hotspot of HPV integration at MACROD2; involved in impaired PARP1 activity and chromosome instability.