Cellular senescence is a common outcome of cytostatic and cytotoxic cancer therapies. While in some contexts therapy-induced senescence can drive tumor growth suppression and anti-tumor immunity through the senescence-associated secretory phenotype (SASP), in others it can promote metastatic progression and immune suppression. A systematic interrogation of the impact of different classes of therapy on heterogeneous senescent phenotypes is required to effectively apply these drugs in specific cancer contexts and to rationally design combination treatments. Using genetically-defined human and murine prostate cancer cell lines, we found that many classes of cancer therapeutics, including chemotherapies and targeted Aurora kinase and CDK inhibitors, could induce cellular senescence, with DNA-damaging agents mediating the most robust growth arrest and SASP. The SASP produced by chemotherapy-induced senescence, particularly with docetaxel, contained not only inflammatory factors that influence immune responses, but also ECM remodeling factors that facilitate tumor cell dissemination. Though docetaxel treatment could induce senescence and reduce tumor growth in syngeneic prostate cancer mouse models, it was not sufficient to activate anti-tumor immunity or slow metastatic dissemination. Senolytic therapies targeting the pro-survival BCL2 and IAP pathways upregulated after docetaxel-induced senescence effectively killed senescent tumor cells through multiple cell death pathways, remodeling the inflammatory SASP to repolarize myeloid phenotypes and potentiate CD8+ T cell activation to further block tumor growth and suppress metastasis. These results suggest that senolytic agents can enhance the immunogenicity and anti-metastatic potential of chemotherapy used for treating advanced prostate cancer patients.

The paradigm in the field of oncolytic virotherapy proposes that tumor cell killing by an oncolytic virus (OV) culminates in the priming of antitumor CD8+ T cells. However, this ignores the impact a highly immunodominant antiviral response against the OV has on the subdominant antitumor response, particularly regarding the naturally low affinity of tumor antigens to their cognate T cell receptors. To investigate this experimentally, we first studied the interaction between the two responses in B16 and MC38 tumor models both expressing ovalbumin (OVA). Contrary to the accepted paradigm, the inflammatory vesicular stomatitis virus (VSV) failed to expand OVA-specific T cells in vivo unless armed with tumor-associated antigen (TAA). In fact, treatment with the control VSV led to the ablation of antitumor T cells and a shift toward dysfunction as determined by the upregulation of markers including LAG3 and CD39 correlating with lower rates of survival. Combination with anti-PD-1 immune checkpoint blockade therapy significantly improved survival only when VSV expressed TAA. VSV expressing altered peptide ligand (APL) variants of tumor antigens, which evade mechanisms of central tolerance expanded near-self antigen specific T cells with the ability to cross react with tolerized tumor antigens, thus providing an antitumor effector population capable of proliferating in the presence of a potent antiviral response. Taken together, these findings offer a rational approach to OV design which preserves acute antitumor therapy provided by antiviral innate and T cell responses whilst promoting the induction of tumor-specific T cells.

Colorectal cancers (CRC) with microsatellite stability (MSS) and instability (MSI) differ in tumor microenvironment (TME) composition and clinical treatment and outcomes. While MSI CRC is considered to be sensitive to immune checkpoint blockade therapy, MSS tumors are largely resistant. Characterizing the spatial TME differences between MSS and MSI tumors could provide insights to improve immunotherapy efficacy. Here, we profiled an integrated single-cell and spatial transcriptomic atlas of MSS and MSI CRC across independent cohorts and platforms. Spatial mapping revealed subtype-specific boundary microenvironments coupled to distinct malignant epithelial states. Cancer cells in a fully mesenchymal epithelial-mesenchymal-transition (EMT) state (EMT-II subtype) were enriched near the tumor boundary in MSS, while cancer cells with metabolically active EMT programs (EMT-III subtype) and interferon states were enriched in MSI and displayed a more dispersed distribution. A boundary-proximal interaction network selectively enriched in MSS was characterized by the accumulation of glial-like and tip-like cells around tumor boundary, which preferentially co-localized with EMT-II state tumor cells. The network was linked to extracellular matrix remodeling and EMT malignant cell states. Further, development of a cross-platform classifier TiGELR, a machine learning-derived tip cell-glial cell-EMT II tumor cell ligand-receptor signature, accurately distinguished MSS from MSI and stratified immunotherapy outcomes. Together, this study characterizes the spatial heterogeneity of tumor states and TME programs in CRC and provides a translational framework for improved CRC stratification and immunotherapy guidance.

Pancreatic ductal adenocarcinoma (PDAC), the most common subtype of pancreatic cancer, is a deadly disease with a complex tumor microenvironment (TME). Cytotoxic combination chemotherapy treatments are the mainstay of PDAC therapy, but patients rapidly develop chemoresistance, highlighting the need to elucidate how chemotherapy alters the TME and whether these changes drive chemoresistance. Here, we examined matched pre- and post-treatment tissue specimens using single-cell RNA-sequencing and found near-universal enrichment after treatment of axonal guidance genes in cancer-associated fibroblasts (CAFs). These neural CAFs were enriched near sites of perineural invasion, coinciding with regions of increased tumor cell proliferation, and were enriched in tumor areas distant from nerves after chemotherapy. Metastatic recurrent lesions had the highest prevalence of neural CAFs versus primary tumors and untreated metastases. Neural CAFs showed elevated non-canonical WNT mediators and axonal guidance genes, which complemented matching cognate binding partners in tumor epithelial cells, suggesting a role in tumor-stroma crosstalk. Additionally, in vitro studies revealed enrichment of axonal guidance genes in patient-derived CAF lines upon exposure to chemotherapy or tumor cells. Altogether, these findings implicate fibroblast-derived axonal-guidance genes in promoting PDAC invasion and point to a promising therapeutic target for this disease.

While the genetic paradigm of cancer is powerful, it remains incomplete. For example, high mutational burdens are commonplace in homeostatically-stable epithelia, but the presence of driver mutations alone does not result in cancer. Here, we revealed additional factors contributing to the eco-evolutionary dynamics of carcinogenesis. The dynamics of carcinogenesis were tracked from initiation to emergence using a UV-driven model of squamous cell carcinoma, via in vivo serial 3D reconstruction of >25,000 fluorescently labeled keratinocyte clades (cells expressing a single fluorophore and related by descent). While median and mean clade sizes (8-16 cells) differed little with UV exposure, UV exposure resulted in large goliath clades (>~4.2×106 µm3; >500 cells). Of note, goliath formation preceded the acquisition of established driver mutations, and only a subset of goliaths exhibited both greater mutational loads and dense aggregations of cells (micro-lumps). Of 21 randomly selected goliath clades in macroscopically normal-appearing skin tracked weekly, 2 developed into visible lesions, while an adaptation of the Drake equation placed the probability of this occurring at less than 10-6. The earliest molecular signatures based on single-cell RNA-sequencing of irradiated skin reflected epidermal de-differentiation and immunosuppression. Overall, this study documents skin cancer initiation due to UV exposure from changes in clade distribution through macroscopic lesion development arising from goliath clades. These data highlight these transitions in relation to known driver mutations and transcriptomic changes, suggesting a possible explanation for why cancers are rare relative to the degree of somatic mosaicism present.

Castration-resistant prostate cancer (CRPC) progression despite treatment with potent androgen receptor (AR) antagonists such as enzalutamide is a major clinical challenge. The mitotic kinase BUB1B is a central member of an oncogenic seven-gene network that drives CRPC. Here, we characterized BUB1B as an actionable therapeutic target for treatment-resistant PC. High BUB1B expression correlated with PC progression and aggressiveness. BUB1B depletion blocked CRPC cell proliferation through accumulation in G2/M and mitotic delay. Conversely, ectopic expression of BUB1B conferred castration and enzalutamide resistance to androgen-dependent PC cells in vitro and in vivo. BUB1B promotion of CRPC was not dependent on AR canonical signaling as assessed through AR knockdown and PROTAC-mediated AR degradation. BUB1B kinase activity was necessary for CRPC progression, as only wild type (WT), but not two kinase-dead mutants, promoted castration-resistant growth, and BUB1B kinase activity was required to maintain castration resistance. Expression of the primary substrate of BUB1B, CENP-E, also promoted CRPC progression, while a phosphodeficient mutant of the BUB1B phosphorylation site was ineffective. Moreover, only a phosphomimic mutant of CENP-E rescued growth after BUB1B depletion in CRPC cells, indicating that BUB1B-dependent phosphorylation of CENP-E was sufficient for progression and necessary to sustain CRPC growth. Targeting CENP-E with the clinically tested, small-molecule GSK923295 phenocopied BUB1B knockdown, sensitized resistant cells to enzalutamide and suppressed growth of enzalutamide-resistant xenografts in vivo. These data support BUB1B kinase as a driver of castration and enzalutamide resistance, positioning CENP-E inhibition as an attainable approach for treatment-resistant disease.

Metastatic cancer cells must adapt to the physical properties of distant tissues, yet the consequences of such mechanical adaptation for immune surveillance remain poorly understood. In Immunity, Elbanna and colleagues reveal an unexpected trade-off between mechanical fitness and immune vulnerability: Environmental rigidity induces cancer-cell stiffening, enabling robust colonization of rigid bone in the absence of effective cytotoxic immunity. However, this mechanically adapted state also increases susceptibility to cytotoxic lymphocytes, allowing immunosurveillance to preferentially eliminate stiffened cancer cells and suppress bone metastasis in immunocompetent hosts. SPP1 contributes to this environmentally induced mechanical adaptation and its associated immune vulnerability. This study also highlights a broader mechanical dialogue between the metastatic niche, cancer cells, and the immune system, in which adaptation to one physical constraint may create vulnerability to another. Mechanistically, cancer-cell mechanics may represent more than a consequence of tumor progression-it may constitute an actionable determinant of immune susceptibility. Manipulating the mechanical state of cancer cells could therefore complement strategies aimed at enhancing immune-cell function. The study raises the intriguing possibility that the very adaptation that enables cancer cells to establish themselves within a rigid metastatic niche may simultaneously expose a therapeutically exploitable mechanical vulnerability to immune surveillance.

Pancreatic ductal adenocarcinoma (PDAC) is characterized by early metastatic dissemination and poor clinical outcomes. Although SMAD4 is frequently altered in PDAC, the majority of tumors retain wild-type SMAD4, which paradoxically acquires pro-metastatic functions during disease progression. Uncovering how SMAD4 transcriptional output is reprogrammed to support metastasis in advanced PDAC could reveal strategies to prevent and treat metastasis. Here, we identified protein arginine methyltransferase 1 (PRMT1) as a critical modifier that mediates a metastasis-promoting transcriptional state of SMAD4. PRMT1 catalyzed asymmetric dimethylation of SMAD4 at arginine 272 (R272), a modification that did not alter SMAD4 expression but stabilized nuclear SMAD2/3-SMAD4 complexes and redirected SMAD4 chromatin engagement toward epithelial-mesenchymal transition (EMT) gene programs. Mechanistically, R272-methylated SMAD4 promoted the recruitment of a BRG1-CTCF transcriptional complex, enabling chromatin-dependent activation of pro-metastatic transcriptional outputs. Importantly, pharmacological inhibition of PRMT1, particularly in combination with BRG1 degradation, dismantled methylation-dependent SMAD4 transcriptional complexes, suppressed EMT programs, and markedly reduced liver metastasis in preclinical PDAC models. Together, these findings uncover a post-translational mechanism that governs SMAD4 transcriptional specificity and identify PRMT1-dependent methylation as a therapeutic vulnerability in SMAD4-wild-type pancreatic cancer.

More than three decades have passed since the identification of BRCA1 as the first breast cancer susceptibility gene (BCSG). Since then, substantial progress has been made in pinpointing BCSGs and estimating the associated risk of developing BC. Simultaneously, new challenges and open questions have also emerged, such as the potential associations between BCSGs and metastasis in BC patients. In this review, we discuss available data from clinical and experimental studies assessing the association between germline pathogenic variants (GPVs) in BCSGs and metastasis pattern. To help guide future studies addressing the current knowledge gaps, the review outlines clinical outcomes and four variables to be considered: 1) age and ethnicity; 2) clinical, molecular, and pathological characteristics; 3) treatment response; and 4) the specificity of BSCG variants. The synthesis of data from mouse models and human-derived materials supports a speculative model where the crosstalk between BC cells and the microenvironment defines the metastasis pattern in carriers of GPVs in BCSGs. An experimental framework is proposed for testing this model in future studies that could parallel comprehensive clinical studies addressing the outlined clinical outcomes and variables.

Metastasis remains the leading cause of cancer mortality, yet effective therapies for inhibiting and treating metastasis are limited. Therapeutic responses are influenced by organ-specific immune microenvironments, highlighting the need to develop strategies to pharmacologically modulate these niches. Here, using the clinical-stage inhibitor ABBV-CLS-484 (AC484) as a chemical probe, we demonstrated that systemic PTPN1/2 inhibition remodels the pulmonary myeloid landscape, specifically activating alveolar macrophages (AMs) toward a tumoricidal state. Integrated single-cell and spatial transcriptomics and functional assays revealed that AC484 promotes accumulation, IFNγ production and responsiveness, and tumor-killing activity of AMs within metastatic lesions. Depletion of AMs diminished the anti-metastatic efficacy of AC484. Mechanistically, inhibition of PTPN1/2 amplified IFNγ-STAT1 signaling in AMs, and disrupting this pathway impaired the tumor control capability of AC484. These findings delineate a distinct innate immune axis where PTPN1/2 acts as a molecular "brake" on AM activation, suggesting that pharmacologically unleashing tissue-resident macrophages offers a therapeutic strategy to overcome metastatic progression, particularly in microenvironments where adaptive immunity is insufficient.

The aged tumor microenvironment can impair antitumor T cell function, but the molecular regulators that become limiting in this setting remain poorly defined. In a recent issue of Cell, Chen and colleagues harness in vivo CRISPR screening to compare the effects of genetic perturbations in tumor-reactive CD8+ T cells across young and aged hosts. The screen reveals that increased T cell persistence or an effector-like transcriptional state does not necessarily translate into improved tumor control and identifies Dusp5 and Zfp219 as distinct functional regulators. DUSP5 broadly restrains ERK-dependent proliferation, and its loss improves tumor control in both young and aged mice. ZFP219, by contrast, preferentially limits cytotoxicity in aged hosts; its deletion increases granzyme expression and improves tumor control specifically in the aged setting. Human tumor datasets show that ZNF219 expression in intratumoral CD8+ T cells increases with age and is associated with poorer clinical outcomes. Moreover, Zfp219 loss enhances the response to PD-1 blockade in aged mice, producing complete tumor clearance in a subset of animals and durable protection after rechallenge. Together, these findings show that host age can reshape the functional consequences of T cell perturbations and reveal age-dependent genetic vulnerabilities with potential therapeutic relevance.

Airway hillocks are specialized, stratified squamous epithelial structures featuring luminal barrier cells supported by a dedicated basal stem cell population. In this issue of Cancer Research, Izzo and colleagues identify a distinct population of slow-cycling KRT13+ hillock-like tumor cells in lung squamous cell carcinoma, a cell state conserved across multiple squamous cell carcinoma (SCC) models. Mechanistically, KLF4 drives KRT13 expression, correlating with enrichment of potential therapeutic targets and resistance to platinum-based chemotherapy. By linking the physiologic epithelial barrier to therapeutic resistance, this study unlocks a previously uncharacterized mechanism underlying SCC biology. See related article by Izzo et al., p. 4472.

Human papillomavirus (HPV) plays a pivotal role in various malignancies, including cervical, anogenital, head, and neck cancers. Despite the availability of highly effective prophylactic vaccines, many individuals remain susceptible to HPV-driven cancers due to barriers such as limited vaccine access, lack of awareness, or personal preferences. Current treatments primarily target lesions without eradicating persistent HPV infections, leading to an increased risk of subsequent HPV-associated cancers. This scenario underscores an urgent need for innovative treatment modalities aimed at eliminating persistent HPV infections. Here, we developed NTX250, an mRNA-based therapeutic platform engineered to deliver HPV type 16 (HPV16) E6 and E7 antigens, in conjunction with the immunomodulators IL-12 and LIGHT. A lipid and ionizable peptoid nanoparticle system facilitated precise intralesional delivery of NTX250. Localized NTX250 administration in HPV16-transformed tumor-bearing models led to complete tumor regression and established durable, antigen-specific immune memory. Replacing the HPV antigens with a construct comprising colorectal cancer cell specific neoepitopes enabled stimulated antitumor immunity and suppressed tumor growth, supporting the generalizability of the approach. Overall, NTX250 represents a promising non-surgical immunotherapy platform that is capable of eliciting robust and targeted anti-tumor immune responses across diverse malignancies. This adaptable mRNA nanoparticle approach enables the co-delivery of tumor-specific antigens and immunomodulators, with the potential to target tumor-associated antigens beyond HPV.

Fungi have been detected within human tumors and shown to support tumor progression. A better understanding of how intratumoral fungi evade innate immunity, remodel the tumor microenvironment (TME), and promote tumorigenesis may provide insights into cancer pathogenesis and therapeutic strategies. Here, we showed that aggressive human head and neck squamous cell carcinomas (HNSCCs) harbor an elevated fungal burden, including the environmental fungus Cladosporium cladosporioides, and are infiltrated by IL1B-high neutrophils with impaired reactive oxygen species (ROS) production and phagocytosis, as well as IL1B-high macrophages. In a mouse model in which Ikka ablation drives tumorigenesis through EGFR and STAT3 activation, oral C. cladosporioides infection recapitulated key features of the human HNSCC TME, elevated serum IL-1β and IL-17A levels, and promoted both oral and skin SCC development. Oral fungal infection also increased the acidic metabolites uric acid and lactate in the TME. These metabolites enhanced C. cladosporioides-induced IL-1β production while reducing ROS production in neutrophils, thereby impairing fungal clearance. Mechanistically, C. cladosporioides, IL-1β, and IL-17A activated STAT3 and cyclin D1 signaling in SCC cells. Epithelial Stat3 deletion abrogated both Ikka loss-driven and fungus-enhanced oral and skin carcinogenesis, reduced macrophage accumulation, restored normal oral neutrophil phenotypes, and cleared oral fungal infection. Furthermore, IL-1β induced by C. cladosporioides inoculation drove systemic inflammation that promoted skin SCC via an IL-1β/IL-1R feedback loop involving neutrophils and macrophages. Together, these findings identify a fungus-driven immunosuppressive circuit in which tumor-derived acidic metabolites impair antifungal immunity, thereby promoting both local and distal SCC progression.

Receptor tyrosine kinases (RTKs) classically function as oncogenic drivers that promote survival and proliferation upon ligand binding. A subset of RTKs can also function as dependence receptors, inducing apoptosis in the absence of their ligands. Genetic alterations that enhance RTK signaling are well characterized in cancer and can be targeted with kinase inhibitors, which show limited efficacy in some clinical settings. Elucidation of whether oncogenic mutations can promote tumorigenesis by directly abolishing the pro-apoptotic activity of dependence receptors could help improve strategies to target RTKs. Here, we identified MET exon 14 skipping (METex14Del) as a paradigmatic example of an oncogenic alteration that drives tumorigenesis through genetic inactivation of the dependence receptor function of an RTK. METex14Del removed both the caspase cleavage site and adjacent CBL-binding motif, preventing generation of the pro-apoptotic p40MET fragment while sustaining oncogenic MET signaling. Uncoupling regulatory functions of MET using genome editing showed that loss of apoptosis capacity is a critical determinant of METex14Del-driven tumorigenesis. Combined-but not individual-mutation of the caspase and CBL sites was sufficient to recapitulate resistance to apoptosis and tumor growth induced by METex14Del in HGF-humanized mouse models. Importantly, inducible re-expression of p40MET in METex14Del-expressing cells restored apoptotic sensitivity, decreased tumor formation in vivo, and resensitized tumors to capmatinib. Together, these findings redefine RTKs as receptors with dual oncogenic and tumor-suppressive functions and show that disruption of dependence receptor-mediated apoptosis is an oncogenic mechanism. These results provide a conceptual framework explaining why therapies targeting only RTK signaling may fail and support strategies restoring dependence receptor function to achieve durable tumor suppression.