Biology subjects

Janic, A.

Publications and source records attributed to Janic, A..

6 recordsLinked to original sources

bioRxiv2026

A p53-dependent FBXO44-RAD18 axis limits mutagenesis by terminating translesion DNA synthesis

DNA lesions continually challenge genome replication and threaten genome integrity. DNA damage tolerance pathways, including translesion DNA synthesis (TLS), allow cells to bypass lesions and prevent stalled forks from collapsing into double-strand breaks. Because TLS polymerases are intrinsically error-prone, however, this pathway must be tightly restrained; persistent or deregulated TLS can increase mutagenesis, create therapeutic vulnerabilities, and promote aggressive cancer phenotypes. Through integrated transcriptional profiling, genome-wide CRISPR/Cas9 screening for replication-stress sensitivity, and complementary proteomic analyses, we identify F-box protein 44 (FBXO44) as a late p53-responsive regulator of the TLS mediator RAD18. FBXO44 promotes RAD18 ubiquitination during recovery from replication stress and facilitates shutdown of RAD18-dependent PCNA monoubiquitination. Consistently, FBXO44 loss delays resolution of replication stress and TLS signaling, increases mutation frequency, and is associated with elevated mutational burden and therapy resistance in experimental models and patient datasets. These findings define a p53-FBXO44-RAD18 regulatory axis that limits mutagenic TLS and helps safeguard genome integrity after replication stress.

cancer biology↗

bioRxiv2026

Nuclear adenosine metabolism defines a metabolic vulnerability unmasked by TP53 loss

Metabolic adaptation is essential for cells experiencing chronic genomic stress, yet how such adaptations are organized at the nuclear level remains poorly understood. Loss of TP53 is associated with elevated genomic instability, DNA damage and altered metabolic requirements, creating context specific dependencies. Here, we identify a requirement for de novo purine biosynthesis in TP53-deficient cells, with a pronounced dependence on adenosine related metabolism. Perturbation of purine synthesis increases DNA damage and reduces nuclear ATP availability, particularly in TP53-deficient cells, and is accompanied by a rapid increase in histone methylation. This chromatin response is also induced by acute DNA damage and occurs with fast kinetics, indicating that histone methylation is an early, intrinsic feature of the nuclear stress response rather than a secondary epigenetic remodeling. Interfering with histone methylation is associated with reduced nuclear ATP levels and impaired DNA damage resolution, linking chromatin state to nuclear energy homeostasis. Genetic disruption of the purine biosynthesis enzyme PFAS selectively impairs the growth of TP53-deficient tumours in vivo, establishing the physiological relevance of this metabolic dependency. Together, these findings reveal nuclear adenosine metabolism as a compartmentalised adaptive response to genotoxic stress and highlight chromatin associated methylation as a key feature of nuclear metabolic regulation unmasked by TP53 loss.

cancer biology↗

bioRxiv2025

Dual inhibition of the nonsense mediated mRNA decay enhances tumour immunogenicity, drives immunoediting, and potentiates checkpoint blockade

Immune checkpoint blockade has transformed cancer therapy, but current biomarkers such as tumour mutation burden often fail to reliably predict clinical benefit. One proposed reason for this discrepancy is the activity of nonsense-mediated mRNA decay (NMD), a cellular quality-control pathway that degrades mutant transcripts, potentially reducing the presentation of neoantigens that would otherwise stimulate anti-tumour immunity. To address this, we identified publicly available small-molecule inhibitors targeting the NMD factors SMG5 and SMG7 (NMDi), which we have prioritise as the NMD components most strongly associated with NMD efficiency across TCGA tumours, and evaluated their therapeutic potential in vivo. In a syngeneic, DNA repair deficient mouse model of lung adenocarcinoma, NMDi treatment alone substantially reduced tumour burden, and its combination with anti-PD-1 therapy led to additive benefit either treatment alone. These effects were immune-dependent and specifically required CD8{square} T cells. Transcriptomic and single-cell analyses revealed that NMDi reprograms the tumour immune microenvironment, enriching for clonally expanded, cytotoxic CD8{square} T cells and altering macrophage states toward those associated with tumour regression. Whole-genome sequencing of tumours revealed that NMDi also promotes immunoediting, leading to negative selection against immunogenic mutations and coding indels, with selective pressure comparable to or greater than that induced by anti-PD-1 treatment. Guided by these results, we generated a new protein language model trained on tumour mutations that can identify neopeptides with immunogenic properties, revealing that the NMDi tumour landscape provides a rich genomic and immunopeptidomic setting for exposing neoantigens that evade immunoediting. Together, these pre-clinical and integrative genomic-transcriptomic insights position NMD inhibition as a promising immunostimulatory strategy that can potentiate immune checkpoint blockade efficacy in tumours.

cancer biology↗

bioRxiv2025

Site-specific immunogenicity and anti-PD1 response in mismatch repair deficient lung adenocarcinoma models

Immunotherapy has revolutionized cancer treatment, yet responses vary significantly based on tumour characteristics and microenvironment. Here, we developed and analysed subcutaneous and orthotopic immunocompetent mice models of mismatch repair-deficient (dMMR) lung adenocarcinoma (LUAD) by selectively ablating Mlh1. Subcutaneous tumours demonstrated partial sensitivity to anti-PD1 therapy, characterized by tumour volume reduction without significant changes in immune infiltration. In contrast, orthotopic tumours exhibited robust responses, with substantial reductions in tumour burden, enhanced immune infiltration, and increased CD4+ memory T cells, highlighting the critical role of anatomical site and tumour microenvironment in shaping immunotherapy outcomes. Our findings emphasise the relevance of orthotopic models for preclinical evaluation and suggest that they more accurately reflect clinical responses to immune checkpoint blockade in dMMR LUAD.

cancer biology↗

bioRxiv2023

Adaptation to ARF6-depletion in KRAS-driven PDAC is abolished by targeting TLR2

Metastasis is responsible for nearly 90% of all cancer-related deaths. Despite global efforts to prevent aggressive tumours, cancers such as pancreatic ductal adenocarcinoma (PDAC) are poorly diagnosed in the primary stage, resulting in lethal metastatic disease. RAS mutations are known to promote tumour spread, with mutant KRAS present in up to 90% of cases. Until recently, mutant KRAS remained untargeted and, despite the recent development of inhibitors, results show that tumour cells develop resistance. Another strategy for targeting mutant KRAS-dependent PDAC proliferation and metastasis may come from targeting the downstream effectors of KRAS. One such axis, which controls tumour proliferation, invasiveness and immune evasion, is represented by ARF6-ASAP1. Here we show that targeting ARF6 results in adaptive rewiring that can restore proliferation and invasion potential over time. Using time-series RNA and ATAC sequencing approaches, we identified TLR-dependent NF{kappa}B, TNF and hypoxia signalling as key drivers of adaptation in ARF6-depleted KRAS-dependent PDAC. Using in vitro and in vivo assays, we show that knocking down TLR2 with ARF6 significantly reduces proliferation, migration and invasion. Taken together, our data shed light on a novel co-targeting strategy with the therapeutic potential to counteract PDAC proliferation and metastasis. GRAPHICAL SUMMARY O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=120 SRC="FIGDIR/small/569405v1_ufig1.gif" ALT="Figure 1"> View larger version (37K): org.highwire.dtl.DTLVardef@192ac2org.highwire.dtl.DTLVardef@4659e5org.highwire.dtl.DTLVardef@b7e225org.highwire.dtl.DTLVardef@6019aa_HPS_FORMAT_FIGEXP M_FIG C_FIG

cancer biology↗

bioRxiv2022

Combined absence of TRP53 target genes ZMAT3, PUMA and p21 cause a high incidence of cancer in mice

Transcriptional activation of target genes is essential for TP53-mediated tumour suppression, though the roles of many TP53-activated target genes in tumour suppression remains poorly understood. Knockdown of ZMAT3 in haematopoietic stem/progenitor cells by shRNA caused leukaemia only with the concomitant absence of the pro-apoptotic BCL-2 family member PUMA and the CDK inhibitor p21. We were interested to further investigate the role of ZMAT3 in tumour suppression beyond the haematopoietic system. Therefore, we generated Zmat3 knockout and compound gene knockout mice, lacking Zmat3 and p21, Zmat3 and Puma or all three genes. Puma-/-p21-/-Zmat3-/- triple knockout mice developed tumours at a significantly higher frequency compared to wild type, Puma-/-Zmat3-/- or p21-/- Zmat3-/-deficient mice. Interestingly, we observed that the triple and Puma-/-Zmat3-/- double deficient animals succumbed to lymphoma, while p21-/-Zmat3-/- animals developed mainly solid cancers. This analysis suggests that in addition to ZMAT3 loss, additional TRP53-regulated processes must be disabled simultaneously for TRP53-mediated tumour suppression to fail. Interestingly, our findings also reveal that the absence of different TRP53 regulated tumour suppressive processes changes the tumour spectrum, which suggests that different TRP53 tumour suppressive pathways are more critical in different tissues.

cancer biology↗