The Journal of Pathology

Epidermodysplasia verruciformis (EV) is characterized by susceptibility to cutaneous {beta}-human papillomaviruses, persistent viral lesions and an increased risk of cutaneous squamous cell carcinoma (cSCC). We investigated whether expression of Toll-like receptors 3, 4, 5 and 9 (TLR3, TLR4, TLR5 and TLR9) differs across histological states within EV. Immunoreactivity was quantified by digital H-score using QuPath in 97 specimens from 28 patients, comprising 13 lesion-free skin samples, 15 flat warts and 69 cSCCs. Prespecified comparisons evaluated flat wart versus lesion-free skin, cSCC versus non-neoplastic tissue and invasive versus in situ cSCC, with invasive tumour differentiation assessed secondarily. Patient-clustered generalized estimating equations and false-discovery-rate (FDR) correction were used for inference. After correction for multiple testing, TLR9 H-scores were higher in flat warts than in lesion-free skin ({beta}=60.58; q=0.0332). Compared with non-neoplastic tissue, cSCC showed lower TLR3 ({beta}=-81.40; q=0.00745), higher TLR4 ({beta}=55.59; q=0.04793) and lower TLR9 expression ({beta}=-34.80; q=0.03412). TLR5 showed a nominal increase in cSCC that did not meet the FDR threshold. None of the four receptors differed significantly between invasive and in situ cSCC, and no differentiation trend remained significant after FDR correction. These findings show receptor-specific differences in TLR expression across histological states of EV, particularly involving TLR3, TLR4 and TLR9, although the diagnostic and prognostic significance of these tissue patterns remains to be established.

Background: Pre-operative triage of adnexal masses with serum CA-125, HE4, and ultrasound (O-RADS) has limited accuracy, contributing to unnecessary surgery. We develop and validate a first of its kind, biomarker panel-free plasma proteomic classifier that distinguishes malignant from benign adnexal masses from a single blood draw, operating directly on discovery-mode mass spectrometry. Methods: In this multicenter prospective observational study, plasma from women with adnexal masses and from healthy controls at a large urban academic center (discovery and four validation cohorts) and an external academic center from another Urban-suburban area (external validation) was analyzed by data-independent-acquisition mass spectrometry (Orbitrap Astral), quantifying >1,000 proteins per sample. Cancerous (malignant, borderline adnexal mass, or metastasis to ovary) versus benign adnexal masses were classified with ADAPT-MS (Adaptive Diagnostic Architecture for Personalized Testing by Mass Spectrometry), which retrains an ElasticNet model for each sample based on the proteins measured. The primary outcome was discrimination (area under the receiver operating characteristic curve [AUC]). Pre-operative O-RADS scores and serum CA-125 were compared and combined with proteomics on matched subsets. Findings: Using a discovery cohort (n=1062), an ADAPT-MS classifier, validated across five independent cohorts (n=623), achieved a summary AUC of 0.835 (cohort range 0.779-0.904). Among patients with pre-operative O-RADS (n=231), proteomics (AUC 0.852) was comparable to O-RADS alone (0.863) and combining them raised discrimination to 0.922. Proteomics outperformed serum CA-125 (0.915 versus 0.777; n=125) and proteome-derived ROMA-like and two-marker surrogates. Biologically, the classification-relevant proteins are enriched for host response proteins rather than tumor cell associated protein changes, comprising ECM remodeling, complement and innate immune response pathways. This explains good detection of tumor with heterogenous pathology and also metastasis to ovary. Interpretation: A single plasma proteomic measurement interpreted using adaptive machine learning discriminates malignant from benign adnexal masses with good internal and external validation, and is complementary to ultrasound, warranting prospective evaluation as a panel-free diagnostic adjunct to imaging.

Individuals with fibrodysplasia ossificans progressiva (FOP), a rare genetic disorder caused by mutations in the bone morphogenetic protein receptor ACVR1 (also known as ALK2), experience progressive and severely debilitating endochondral heterotopic ossification (HO). Previous studies have identified fibro-adipogenic progenitors (FAPs) as a major cellular source of HO in FOP mouse models. Here, we used mRNA sequencing of FAPs isolated from injured muscle of FOP mice to capture the earliest gene expression changes associated with the transformation of muscle tissues into bone. Whereas the transcriptomes of mutant and wild-type FAPs were indistinguishable prior to injury and at 1 day post injury, dramatic dysregulation of gene expression was observed at 3 and 5 days after injury. Surprisingly, gene expression changes suggested early specification of osteochondral lineages by 3 days post injury, approximately 3 to 4 days before the appearance of histologically identifiable cartilage. We identified dysregulation of genes encoding components of major signaling pathways, cell cycle regulators, extracellular matrix components, and hypoxia response mediators, and showed that these gene expression changes are temporally associated with abnormal population growth of mutant FAPs. We further demonstrated that treatment of FOP mice with either an anti-activin A monoclonal antibody or the ACVR1 kinase inhibitor BLU-782 (IPN60130; fidrisertib) normalized the expression of the majority of dysregulated FAP genes. However, the relative efficacy of the drugs differed, and distinct sets of overlapping genes were normalized by the treatments. The substantial transcriptional changes caused by these drugs in FAPs from normally regenerating muscle were also enumerated and described. These findings define early transcriptional events associated with pathogenic FAP reprogramming and provide a molecular framework for understanding the shared and distinct effects of activin A and ACVR1 inhibition.

Leiomyosarcoma is an aggressive soft tissue sarcoma that metastasizes preferentially to lung and liver. Because matched primary and metastatic specimens are rarely available, the cellular changes that accompany metastatic progression remain poorly defined. Here we combined single-nucleus RNA sequencing of archival FFPE tissue from four matched primary-metastasis pairs (two lung, two liver metastases; 48,941 nuclei) with imaging-based spatial transcriptomics of an extended tissue microarray cohort of 21 patients (69 cores, 313,218 cells). Malignant cells, not assignable from transcriptomic references alone, were defined by inferred copy number profiles that were concordant with matched DNA methylation arrays and confirmed the clonal origin of each metastasis. Malignant metaprograms were organ-associated, with a stress- and hypoxia-associated program enriched in lung metastases and a proliferative, matrix-remodeling program enriched in liver metastases. Antigen-presenting cancer-associated fibroblasts (apCAFs) were enriched in metastases relative to matched primaries. This shift was reproduced in the spatial cohort (p = 0.001), where apCAFs formed a discrete band at the tumor-organ interface between malignant cells and adjacent parenchyma, whereas they were sparse and randomly distributed in primary tumors. Spatial transcriptomics further resolved the malignant compartment into three histomolecular phenotypes: (i) smooth-muscle-like with myxoid features, (ii) GPNMB with anaplastic features, and (iii) PDGFRB with vessel-rich stroma, each with a concordant immunohistochemical (-SMA, GPNMB, PDGFRB) and morphological correlate. Together, our data provide a matched primary-metastasis reference for leiomyosarcoma, identify apCAFs as a spatially organized, metastasis-associated stromal population, and delineate histomolecular phenotypes recognizable by routine immunohistochemistry, including a GPNMB phenotype potentially amenable to GPNMB-directed therapies.

Background: Pancreatic ductal adenocarcinoma (PDAC) is projected to become the second leading cause of cancer-related mortality, with an increasing incidence and dismal 10% survival at 5 years despite best available care. PDAC is characterized by low tumour cellularity, recurrent driver mutation alterations, and substantial inter and intra-tumoural heterogeneity. The influence of individual genetic features such as sex and ancestry on tumour heterogeneity remains poorly understood. Methods: We assembled a cohort of PDAC across five datasets for a total of 7,527 tumours. Measures of genomic instability were assessed across sex and ancestry on a global level (SNV density and percent genome altered by copy number events), and at a gene level for recurrent events. KRAS variant frequencies, ploidy and mRNA abundance were also evaluated. Ancestry was assigned using ADMIXTURE from germline genotypes where available, and patient reported otherwise. Results: We observed ancestry-specific mutation patterns in global point mutation density, with higher SNV burden in African PDAC tumours and lower SNV burden in Asian PDAC tumours as compared to European tumours. We also identified an ancestry bias in the driver gene, GNAS, in which driver SNVs in GNAS was detected more frequently in those of Asian ancestry, and less frequently in those of African ancestry. No sex- or ancestry-associations were found for KRAS, but individual KRAS variants showed a trend towards ancestry-related variation. Conclusions: These findings demonstrate that ancestry contributes to the genomic heterogeneity of PDAC, shaping both global and gene-specific mutation patterns. This work underscores the importance of including diverse ancestries in PDAC molecular profiling efforts which may inform the development of tailored molecular diagnostics and targeted therapies.

Stromal cell composition has been proposed as a potential biomarker in ductal carcinoma in situ (DCIS) for assessing the risk of subsequent recurrence or progression to invasive breast cancer (IBC). However, the characteristics of the tumor microenvironment within DCIS associated with these outcomes remain poorly understood. Here, we perform spatial transcriptomic analyses of 49 primary DCIS specimens from patients with no recurrence, DCIS recurrence, or recurrence as IBC. Cell mapping reveals spatially organized stromal cell gradients within DCIS, with enrichment of TREM2+ macrophages and myofibroblastic cancer-associated fibroblasts (myCAFs) in tumor-proximal niches. Notably, the abundance of TREM2+ macrophages near tumor nests is associated with subsequent recurrence as IBC. Moreover, ligand-receptor pair analysis identifies GRN--SORT1, SPP1--CD44, and LGALS9--CD44 interactions as spatially plausible signaling interactions between TREM2+ macrophages and epithelial cells. Finally, these findings are validated at the protein level by multiplex immunostaining of serial sections. This study characterizes the spatial landscape of the DCIS tumor microenvironment associated with subsequent recurrence, providing a basis for developing biomarkers of disease progression and identifying potential therapeutic targets.

Abstract Background: High-grade serous ovarian cancer (HGSC) is characterized by extensive genomic heterogeneity and frequent alterations that promote replication stress (RS). Although RS has emerged as a promising therapeutic vulnerability, it remains unclear whether distinct RS-associated genomic alterations generate similar tumour states or drive unique biological programs and therapeutic dependencies. Methods: We developed and characterized a panel of syngeneic HGSC models representing recurrent RS-associated alterations, including overexpression of Ccne1, Brd4, Myc, Ndrg1, Pik3ca, and Brca1 heterozygosity, alongside previously established Pten/Nf1-deficient and Myc overexpressing models. Tumour fitness, transcriptomic programs, histopathology, extracellular matrix composition, immune organization, and therapeutic vulnerabilities were assessed using subcutaneous (s.c.) and intraperitoneal (i.p.) allografts, RNA sequencing (RNAseq), mass spectrometry (MS), cyclic-immunofluorescence (Cyc-IF), and preclinical therapeutic studies. Results: RS-associated genotypes exhibited marked differences in tumour fitness and generated distinct tumour ecosystem states despite sharing a common genetic background. Tumours harbouring BRCA1 heterozygosity displayed reduced tumour fitness, mesenchymal features, extracellular matrix remodelling, stromal expansion, and immune-excluded phenotypes. In contrast, tumours co-expressing Ccne1 and Brd4 exhibited the highest RS level together with strong activation of DNA damage response pathways and limited immune infiltration. Immune characterization identified immune-desert, immune-suppressed, and immune-excluded states across models, demonstrating substantial genotype-dependent immune heterogeneity. Elevated CD47 expression emerged as a defining feature of the Ccne1/Brd4 tumour state and was confirmed in human HGSC specimens with high CCNE1 and BRD4 protein expression. Therapeutic targeting of ATR and CD47 in intraperitoneal Ccne1/Brd4 allografts reduced tumour burden and induced histopathological responses compared with either monotherapy alone, supporting the translational relevance of this RS-high tumour state. Conclusions: Distinct RS-associated alterations do not converge on a common HGSC phenotype but instead generate diverse tumour ecosystem states with unique effects on tumour fitness, stromal remodelling, immune organization, and therapeutic vulnerabilities. These findings highlight the importance of considering the genetic origin of RS when developing therapeutic strategies and establish a framework for investigating genotype-specific vulnerabilities in HGSC.

Current state of the art computational pathology foundation models attain satisfying accuracy most general pathology tasks including detection of pancreatic ductal adenocarcinoma (PDAC) but fail to provide sufficient explainability, operating as "black boxes". Some interpretability effort has been made, with models providing attention maps that project back on the slide the models high attended areas that pushed for the given prediction result, without further naming or reasoning explanation which can limit pathologists trust toward the prediction. We developed C3PRO, a cell-centric framework attempting to provide deeper understanding and explainability, by using embeddings extracted using a pathology foundation model, from cell centered tiles containing both the cell and its close neighborhood, which were then clustered into recurrent morphological phenotypes. A spatial graph was additionally constructed on top of the back-projected vocabulary to account for recurrent motifs. The evaluation of the model performance involved a cohort of 809 patients (825 diagnostic biopsies) using nested cross validation. C3PRO was benchmarked against four different multiple instance learning frameworks and achieved on-par performance for diagnostic (0.958 AUC), survival (0.617) and resectability (0.696) prediction, while providing additional insights compared to the strongest baseline models. Each clustered phenotype was probed and extracted as a representative tile mosaic and annotated by two expert pathologists, constituting a phenotype vocabulary available for statistical analysis. These phenotypes were scored by pathologists with physical brightfield microscopy and replicated the independent statistical significance impact on overall survival prediction from diagnostic biopsies.

Validated biomarkers for identifying patients with early-stage melanomas at high risk of metastasis are limited. We have previously shown that loss of Activating Molecule in Beclin-1-Regulated Autophagy (AMBRA1) and loricrin in the epidermal microenvironment is associated with tumour recurrence. Here we show that endothelial AMBRA1 deficiency contributes to vascular dysfunction and melanoma progression. Melanoma-conditioned media or exposure to TGF{beta}1-3 ligands induced post-transcriptional loss of AMBRA1 in endothelial cells. Transcriptomic profiling in both in vitro and human melanoma single-cell RNA sequencing datasets showed activation of cell-cycle and metabolic programmes alongside suppression of endothelial junction, adhesion and immune-supportive pathways in AMBRA1-deficient endothelial cells. Functionally, AMBRA1 loss increased endothelial cell proliferation, accelerated early tubulogenesis, impaired three-dimensional spheroid adhesion, stabilised endothelial-to-mesenchymal transition-associated transcription factors Slug and Snail, and reduced Claudin-5, VE-cadherin and N-cadherin, indicative of endothelial plasticity and dysfunction. Furthermore, loss of AMBRA1 in a subset of intratumoural and peritumoural blood and lymphatic vessels correlated significantly with metastatic progression in a cohort of 121 non-ulcerated primary AJCC stage I/II melanomas classified as AMBLor at-risk. Collectively, these findings position endothelial AMBRA1 as a regulator of vascular plasticity, dysfunction, and immune-supportive endothelial function in early-stage melanomas, and a marker of a permissive microenvironment associated with metastasis.

Peripheral nerves are increasingly recognized as active components of the tumor microenvironment (TME). Yet, their role in non-muscle-invasive bladder cancer (NMIBC) and response to Bacillus Calmette-Guerin (BCG) remains poorly defined. Using multispectral imaging, we characterized autonomic and sensory nerve populations within the tumor-adjacent stroma of 241 treatment-naive high-risk NMIBC tumor regions from 141 patients. Stromal tumor-associated nerve (STaN) abundance varied substantially across patients and was associated with aggressive clinicopathological features, BCG failure, and disease progression. Unsupervised clustering resolved distinct STaN phenotypic groups with differential clinical and spatial associations. Noradrenergic and a neurochemically heterogeneous STaN populations showed the strongest associations with adverse outcomes. In contrast, a mixed population of nerves with high expression of the synaptic vesicle protein synaptophysin exhibited prominent spatial remodeling associated with BCG failure, despite limited prognostic value by abundance alone. Integration with an independent single-cell atlas nominated cancer-associated fibroblasts and mast cells as candidate cellular intermediaries of neural communication within the TME. Matched transcriptomic profiling revealed coordinated neuronal, extracellular matrix, lipid metabolism, and immune programs in STaN-high tumors, whereas STaN-low tumors preferentially enriched proliferative and hypoxic stress-response pathways. Leveraging these transcriptional features, we developed a transcriptomic classifier that distinguished STaN-high from STaN-low tumors in an independent test cohort (AUC = 0.87) and stratified clinical outcomes in additional patient cohorts. Together, these findings establish tumor innervation as a heterogeneous and clinically relevant feature of the NMIBC microenvironment, with neural abundance, phenotype, and spatial organization capturing distinct aspects of tumor behavior and clinical outcome.

Abstract Background Liposarcoma is a rare cancer, comprising four major histological subtypes: well-differentiated, dedifferentiated, myxoid and pleomorphic liposarcoma. Therapeutic options remain limited for advanced disease, and additional biomarkers that may support biological characterization, diagnosis, or risk stratification are needed. Methods Bulk RNA sequencing (RNA-seq) was performed on paired tumour and adjacent non-tumour tissues from an analysable subset of 16 patients (22 tumour specimens) within a clinicopathological cohort of 21 patients. Differential gene expression analysis, principal component analysis, gene set enrichment (GSEA) analysis and single-sample GSEA (ssGSEA) were used to define subtype-specific transcriptional programs and imprinted-gene dysregulation. PEG10 expression was validated by RT-qPCR and RNA fluorescence in situ hybridization (FISH), and its cellular localization was explored by combined FISH and immunofluorescence for P53, vimentin, Ki67, and CD34. PEG10 expression in liposarcoma was further investigated in an external single-cell RNA-sequencing dataset of dedifferentiated liposarcoma. An exploratory survival analysis was performed in the pan-sarcoma TCGA-SARC cohort. Results Transcriptomic profiling identified distinct subtype-specific gene expression patterns and broad dysregulation of imprinted genes in liposarcoma compared with adjacent non-tumour tissue. Among all the imprinted genes, PEG10 showed a marked tumour-to-normal expression difference and good discriminatory performance between tumour and normal tissues in the discovery cohort (AUC=0.867). In the TCGA sarcoma cohort high PEG10 expression was associated with shorter overall survival. Immuno-FISH and single-cell analyses revealed that PEG10 was predominantly detected in tumour and proliferating cell populations. Importantly, PEG10 expression was higher in high-grade tumours. In bulk RNA-seq data, PEG10 expression correlated with hypoxia, extracellular matrix remodelling and invasion ssGSEA signatures. In the external single-cell RNA-seq dataset PEG10high tumours showed a reduced immune cell infiltration. Conclusions This study provides an integrated transcriptomic characterisation of liposarcoma and identifies PEG10 as a candidate tumour-associated biomarker linked to aggressive disease features. The diagnostic and prognostic value of PEG10 requires validation in larger, independent, subtype-balanced liposarcoma cohorts, and its potential therapeutic relevance requires direct functional investigation.

High-grade serous ovarian carcinoma (HGSOC) is the most common form of ovarian carcinoma and accounts for the majority of deaths from the disease, with fewer than half of patients surviving five years after diagnosis. Bulk transcriptomic profiling has identified molecular subtypes and gene-expression signatures associated with shorter or longer survival. However, because bulk profiling measures a composite of tumour and microenvironmental gene expression, the cellular origins of these signatures and their relationship to the tumour microenvironment remain unresolved. To address this, we applied Xenium spatial transcriptomics to treatment-naive HGSOC tumours from 122 patients using a custom 480-gene panel designed to measure tumour-intrinsic gene expression and distinguish immune and stromal cell populations in the surrounding microenvironment. Analysis of tumour-intrinsic gene expression identified 61 genes nominally associated with overall survival, from which Elastic-Net modelling prioritised five genes associated with longer survival and nine associated with shorter survival. Notably, 46 of the 61 associations did not reach the nominal significance threshold when expression was instead aggregated across all cells from the same patients, highlighting how whole-tissue expression can obscure tumour-cell-specific survival associations. Complementary analysis of tumour-proximal cell populations revealed that multiple immune populations were associated with longer survival, whereas two fibroblast populations were associated with shorter survival. Integrating these analyses revealed that survival-associated tumour-intrinsic gene expression was correlated with the abundance of neighbouring immune and stromal populations that were themselves associated with survival. Pairwise Cox regression demonstrated substantial overlap in the prognostic information captured by these features, while analysis of individual gene-cell combinations showed that survival associations differed according to the abundance of neighbouring populations. Consensus clustering further identified four patient groups with distinct combinations of tumour-intrinsic expression and microenvironmental composition, broadly separating patients with longer and shorter survival. Together, this cohort-scale spatial analysis identifies tumour-intrinsic and microenvironmental features associated with HGSOC survival and reveals how their correlated patterns and combined associations relate to patient outcome.

The prognostic relevance of peritumoral SULF1 transcript signal in oral squamous cell carcinoma (OSCC) is unclear. We assembled a retrospective cohort of 133 patients with 218 primary-site tissue-microarray cores; 131 patients had evaluable boundary features. Multiplex fluorescence imaging combined RNAscope SULF1, CK-pan, and DAPI. Tumor-stroma boundaries were annotated with the SULF1 channel hidden. We screened 50 exported boundary features across cumulative stromal bands of 35-300 um against recurrence-free survival (RFS), overall survival (OS), and disease-specific survival (DSS), with false-discovery-rate correction. The strongest DSS association was signal SD within 150 um (n = 107; 23 disease-specific deaths; HR = 2.20 per SD; 95% CI, 1.64-2.94; q = 2.1 x 10^-6). In 50 repeated 5-fold cross-validations with feature selection repeated within training folds, adding a boundary feature to AJCC stage increased mean held-out DSS c-index from 0.613 to 0.754 (delta C = +0.141; 2.5th-97.5th percentiles across repeats, +0.105 to +0.192). These percentiles describe split variability, not confidence intervals. The 150-um SD feature was selected in 39.2% of DSS training folds. The DSS association persisted after adjustment for mean signal, although the measurements were strongly correlated. Peritumoral SULF1 signal dispersion was associated with outcome beyond an ordinal AJCC-stage model; independent validation is required.

Purpose: To understand the functional impact of macular atrophy (MA) and fibrosis in eyes with treated neovascular age-related macular degeneration (nAMD) based on deep visual sensitivity losses. Design: Cross-sectional study. Participants: One-hundred and nine eyes from 97 individuals with nAMD that had been treated for >=12 months without significant retinal fluid. Methods: All participants underwent defect-mapping microperimetry (DMP) testing - a strategy optimized to quantify the spatial extent of deep visual sensitivity losses through single 10 decibel stimuli presentations - where 208 locations were sampled in the central 8 degrees radius region. Participants also underwent color fundus photography, fundus autofluorescence and OCT imaging, which were co-registered and manually annotated for MA and fibrosis to determine their two-dimensional pointwise extent at individual test locations, and global extent in the corresponding region where DMP was performed. Main Outcome Measures: Pointwise association between the presence of MA and fibrosis with missing a stimulus on DMP and global association between the extent of MA and fibrosis with the proportion of locations missed (PLM) on DMP. Results: At a pointwise level, the presence of MA and fibrosis were independently associated with an increased likelihood of missing a stimulus on DMP (odds ratio = 42.5 and 2.5 respectively; P < 0.001 for both). However, at a global level, only an increasing extent of MA was associated with a significantly higher PLM on DMP (P < 0.001), but not fibrosis (P <= 0.227). MA extent explained a substantial proportion of the variance in the PLM (R2 = 0.97) and there was a very strong correlation between the two parameters ({rho} = 0.93). Conclusions: This study confirmed the expected functional impact of MA and fibrosis on DMP testing at a pointwise level. However, it showed at the global level that only the extent of MA, and not fibrosis, was independently associated with functional loss on DMP, and that there was a very strong structure-function correlation based on MA. These findings thus suggest that evaluating MA alone may be sufficient for capturing structural changes strongly associated with the global extent of deep visual sensitivity losses in those with treated nAMD.

Prostate cancer (PC) bone metastases (PCBM) are a debilitating disease morbidity that primarily affects the axial skeleton. PCBM are predominantly osteosclerotic with mixed osteosclerotic/osteolytic features, including irregular bone deposition, loss of collagen alignment and increased porosity that mimic features of woven bone formed during development and repair. We hypothesize that progression of PCBM is driven by interactions between tumor cells and the bone microenvironment and is associated with changes in the stromal compartment. We performed tandem mass tag mass spectrometry proteomics on lumbar vertebral specimens from 32 cadaveric PCBM specimens and 3 age-matched controls. Unsupervised clustering segregated specimens into three clusters associated with benign, mixed, and osteosclerotic lesion states, characterized by distinct immune-, tumor-, and osteogenic-associated protein signatures. Histological analysis showed tumor infiltration was accompanied by marrow fibrosis and increased collagen III deposition. We identified a marker signature associated with osteosclerotic remodeling and mapped this signature to independent metastatic PC transcriptomic datasets. The proteomics-derived markers reproduced similar molecular groupings at RNA level, and robustly segregated bone PCBMs from soft tissue metastases PC in RNA data. Together, these findings define molecularly distinct states of tumor-driven changes in PCBM that extend beyond histological classification and may inform biomarker development and therapeutic stratification.

Pannexin 1 (PANX1) is a channel-forming glycoprotein that has been implicated in regulating melanoma cell properties such as growth, migration, and invasion. Here we report that the CRISPR-Cas9 mediated ablation of PANX1 or channel inhibition with probenecid shifted A375-P cell cycle distribution towards G2/M, while channel inhibition with spironolactone stalled cell cycle progression at the G1/S checkpoint regardless of PANX1 expression. Bulk RNA sequencing revealed cell cycle related gene expression was downregulated with PANX1 targeting strategies and this was exacerbated when PANX1 deficient cells were treated with spironolactone. When grown as spheroids, we found the deletion and inhibition of PANX1 disrupted spheroid compaction, with spheroids displaying poorly defined borders and reduced circularity. The deletion of PANX1 increased spheroid fragmentation, and this phenotype was intensified when spheroids devoid of PANX1 were treated with spironolactone, highlighting a potential synthetic lethal effect. Using liquid chromatography mass spectrometry, we sought to determine whether PANX1 had binding partners that may act to stabilize spheroid integrity and found that PANX1 co-immunoprecipitated various cell adhesion molecules such as {beta}-actin and F-actin-capping protein subunit -1, suggesting PANX1 and its interacting partners may stabilize cell-cell contacts. When control and PANX1 ablated cells were grown in chick chorioallantoic membrane xenografts to assess their tumour growth characteristics, we discovered that the deletion of PANX1 reduced tumour surface area and viability. Our findings indicate that PANX1 regulates cell cycle progression and the structural architecture of A375-P melanoma tumours, highlighting the therapeutic utility of targeting PANX1 in melanoma.

Pancreatic ductal adenocarcinoma (PDAC) is one of the most aggressive cancers, in part due to a dense and highly plastic tumor microenvironment dominated by cancer-associated fibroblasts (CAFs). In previous work, we identified a CAF population expressing a neural-associated NES+SOX4+NOTCH1+ program that increased with disease progression. The signals driving this state and the mechanisms regulating it remained unclear. Here, we investigated how tumor-derived signals activate this program and whether it represents a stable fibroblast identity or a reversible state. Using spatial transcriptomic data spanning normal pancreas to invasive carcinoma, we identified EGF, FGF2 and BDNF as candidate tumor-to-fibroblast signals associated with disease progression. Functional experiments in patient-derived CAFs and human fibroblast cell lines showed that EGF and FGF2 are sufficient to induce the NES+SOX4+NOTCH1+ program. Growth factor withdrawal reversed the NES+SOX4+NOTCH1+ program at both the protein and transcriptional levels, indicating that this state is dynamic and environment dependent. Single-cell transcriptomic analysis further revealed a multi-phase response involving early loss of fibroblast-associated features, transient activation of neural-associated genes, and a later stress-associated state. Regulatory analyses identified ETS-family transcription factors as key regulators of the program, while phosphoproteomic profiling and inhibitor studies showed that MAPK/ERK signaling plays a central role in its transcriptional activation. Finally, pan-cancer single-cell analysis showed that this state is enriched in CAFs and increases from normal to tumor tissue across multiple cancer types. Together, these findings define a reversible, growth factor-driven CAF program and identify signaling mechanisms that may provide opportunities to selectively modulate tumor-supportive fibroblast states.

Purpose. To determine which proposed keratoconus (KC) mechanisms carry its genetic susceptibility and how it relates to corneal structure, and which describe its corneal tissue. Methods. Six mechanism modules and two attribution sets (transforming growth factor-{beta} [TGF-{beta}] and canonical type-2 atopy) were tested for enrichment in three independent European KC genome-wide association studies (GWAS) and in GWAS of central corneal thickness (CCT) and corneal resistance factor (CRF), with colocalization at matrix loci. Tissue expression was pooled across nine arms from eight studies with control-source meta-regression; activator protein-1 (AP-1)/immediate-early regulatory activity was scored in 107 donors, spatial expression in 21, and serum responses in human and rabbit stromal cells. Results. Extracellular matrix (ECM) was the only module enriched in all three KC sources (P [&le;] 5.46 x 10-) and for CCT, CRF, and thickness-independent CRF (P [&le;] 2.07 x 10-). COL5A1 shared causal variants with CCT in all three sources (posterior probability 0.985-0.991), and FNDC3B and COL1A1 with CRF or its thickness-independent component (0.961-0.986). Pooled, KC corneas had lower general and corneal-local inflammatory and stress/immediate-early expression (log2 fold-change -0.97, -0.98, -0.82; P [&le;] 0.049). In whole-cornea and stromal tissue, ECM expression reversed between postmortem-donor and pathological controls (log2 fold-change +0.36, -2.34), whereas inflammatory and TGF-{beta} programs were lower against both. AP-1/immediate-early regulatory activity was lower in four donor cohorts (Hedges' g -1.50) and stress/immediate-early expression in two spatial cohorts; serum raised immediate-early readouts in human and rabbit cells. Conclusions. KC combines matrix-mechanical genetic susceptibility with a low-inflammatory, low-immediate-early corneal state whose matrix expression direction depends on the control source. Because this susceptibility is genetically shared with corneal thickness and resistance, interventions on the inherited disease are judged by corneal structure and mechanics.

Purpose: A minority of patients with bladder cancer derive lasting benefit from immunotherapy, and current biomarkers capture only part of the biology. We evaluated whether tumor-cell MHC class II defines an immune state associated with outcome across disease stages and after PD-1/PD-L1 blockade. Experimental Design: We localized differential MHC-II activity to malignant epithelial cells by single-nucleus and single-cell RNA sequencing and confirmed HLA-DR expression by immunohistochemistry in 122 specimens. Chromatin profiling and IFN-{gamma} stimulation of cell lines and primary tumors supported derivation of an 11-gene tumor-cell program. Associations were tested in 434 patients with non-muscle-invasive disease, 82 receiving neoadjuvant pembrolizumab, and 288 receiving atezolizumab for metastatic disease. Results: Tumor-cell MHC-II was present in approximately one third of bladder cancers, and malignant cells accounted for the differential signal between MHC-II-high and MHC-II-low tumors. The program was inducible by IFN-{gamma} through JAK/STAT signaling. Within luminal non-muscle-invasive disease, MHC-II-low status was associated with progression (HR 3.31, 95% CI 1.37 to 7.99). In PURE-01, the 11-gene program was associated with pathological complete response (52% versus 24%, p = 0.018) and recurrence-free survival (p = 0.0054), retaining an independent association in models including tumor mutational burden and PD-L1. In bladder-primary metastatic disease, program-high status was associated with overall survival in unadjusted analysis (HR 0.62, 95% CI 0.44 to 0.89); the association did not extend to upper tract tumors (interaction p = 0.0018). Conclusions: Tumor-cell MHC-II defines an inducible state associated with outcomes across bladder cancer stages and after checkpoint blockade, supporting prospective evaluation by RNA and immunohistochemistry.

Purpose: How sarcoma subtypes engage telomerase versus alternative lengthening of telomeres (ALT), and with what consequence, is incompletely defined. Methods: We analyzed 11,792 patients with sarcoma sequenced across 19 centers in AACR Project GENIE v20.0. Telomerase activation was defined as TERT promoter mutation, amplification, or rearrangement, and ATRX/DAXX inactivation served as the ALT proxy, each assessed only where the assay interrogated the locus. Findings were tested for TERT expression in The Cancer Genome Atlas (TCGA), for overall survival (OS) in MSK-IMPACT 50K, and for replication in an independent Foundation Medicine cohort. Mendelian randomization (MR) in FinnGen tested germline telomere length. Results: Telomerase activation (8.8%) and ATRX/DAXX loss (8.0%) were mutually exclusive across subtypes (odds ratio [OR], 0.52; 95% CI, 0.29 to 0.92) and segregated by histology. In MDM2-amplified dedifferentiated liposarcoma (DDLPS), telomerase was activated through TERT amplification (17.2%) or rearrangement (2.7%), never promoter mutation (0/261), and never with ATRX/DAXX loss (0/49; P = .011). TERT-amplified tumors expressed TERT (TCGA; P = .002), and amplification was largely focal. Telomere maintenance alterations were present in 28.0% of DDLPS versus 8.7% of well-differentiated liposarcoma (P < .001) and predicted shorter OS in DDLPS (hazard ratio, 2.04; 95% CI, 1.23 to 3.39; P = .005). ATRX/DAXX loss was more frequent in uterine than extrauterine leiomyosarcoma in GENIE (adjusted OR, 1.96) and in the independent cohort (OR, 1.95; both P < .001). Genetically longer telomeres were associated with liposarcoma (OR per SD, 4.10; 95% CI, 2.15 to 7.81). Conclusion: Sarcoma telomere maintenance is histology-specific and mutually exclusive. In liposarcoma it is acquired at dedifferentiation through focal TERT amplification or ALT and identifies DDLPS with inferior survival.