Cancer Letters

Immune checkpoint inhibitors (ICIs), especially CTLA-4 inhibitors (CTLA-4), exhibit a high incidence of colitis as an immune-related adverse event (irAE) during cancer treatment, severely limiting patient benefit. Clinically, both treatment interruption and existing intervention drugs for ICI-mediated colitis may compromise antitumor efficacy. However, there is inadequate research on the pathogenesis of ICI-mediated colitis, with findings often conflicting. Here, we first established multiple clinically relevant animal models, including an immuno-humanized ICI-mediated colitis model. Through time-series transcriptomics, we discovered that CTLA-4-induced colonic toxicity exhibits characteristics ranging from early metabolic reprogramming represented by glycolysis to later immune disorders represented by Th17 responses. By targeting colonic CTLA-4+ T cells, CTLA-4 blocked CD80/CD86-CTLA-4 interaction, thereby activating the PI3K-AKT-mTOR pathway. Subsequently, mTOR mediated metabolic reprogramming in T cells, shifting them from Treg-biased oxidative phosphorylation to Th17-biased glycolysis. The colonic toxicity of CTLA-4 has also been demonstrated to depend on the PI3K-AKT-mTOR pathway, glycolysis, and Th17 responses. Notably, metformin significantly relieved ICI-mediated colitis by inhibiting mTOR without impeding antitumor efficacy. Collectively, these findings highlighted the metabolic-immune axis in the colonic toxicity of ICI and provided a clinically superior intervention strategy.

BackgroundMetastasis significantly contributes to cancer-related mortality and therapeutic failure. Cancer cells acquire metastatic potential by losing epithelial characteristics and gaining mesenchymal properties through the epithelial-mesenchymal transition (EMT). Differential poly(A) site (PAS) usage, known as alternative polyadenylation (APA), generates mRNA isoforms differing in coding sequence, subcellular localization, stability, or translation efficiency. In cancer, 3'UTR shortening increases expression of proto-oncogenes by escaping miRNA-mediated repression. High expression of CPSF73, which cleaves mRNA precursors at PASs, is associated with unfavorable prognoses in cancer patients. However, the role of APA in regulating EMT remains poorly understood. MethodsIn this study, to investigate the role of APA in EMT, we employed JTE-607, a small-molecule inhibitor of CPSF73 activity, to examine the impact of catalytic inhibition of CPSF73 on proliferation and EMT in MDA-MB-231, MCF7, A549, and HepG2 cancer cells. To identify differential usage of PASs, global profiling of APA changes, and differential gene expression analysis were performed in MDA-MB-231 cells. Additionally, antisense oligonucleotides were used to block the use of a specific PAS whose APA change may be a driver of EMT reversal. ResultsOur findings showed that catalytic inhibition of CPSF73 not only attenuates cancer cell proliferation but also moves the cells away from the mesenchymal state across all four cell lines tested. Global profiling of APA changes following CPSF73 inhibition revealed widespread 3'UTR lengthening and suppression of intronic PASs in MDA-MB-231 cells. APA shifts were observed in key EMT-related genes, accompanied by decreased expression of corresponding proteins across all four cell lines. We used antisense morpholino oligonucleotides to block the proximal PAS of AKT2, shifting the balance of AKT2 mRNA isoforms toward the long isoform. This shift caused EMT reversal, marked by reduced AKT2 protein expression, changes in EMT-related markers, and impaired invasion by MDA-MB-231 cells. ConclusionTogether, these findings identify APA-mediated 3UTR lengthening, with functional consequences in EMT-related genes, as a coordinated mechanism leading to an attenuated EMT phenotype, highlighting a significant connection between APA and the EMT process. Interfering with these APA changes may offer a promising therapeutic strategy to suppress metastasis, with potential efficacy across multiple pathways. Statement of SignificanceOur findings highlight APA-mediated 3 UTR lengthening as a coordinated mechanism that promotes EMT reversal and support CPSF73 inhibition or APA-targeting strategies as potential therapeutic approaches to suppress metastasis across multiple pathways.

Chemoradiotherapy (CRT) induces not only direct tumor cell death but also extensive remodeling of the tumor immune microenvironment. Adaptive natural killer (aNK) cells, initially characterized in chronic viral infection, are increasingly recognized as functionally relevant immune populations in solid tumors, where they may contribute to antitumor immunity and immune memory. However, how aNK cells dynamically respond to chemoradiotherapy and the regulatory mechanisms underlying their activation in solid tumors remain poorly defined. To address this, we analyzed single-cell RNA sequencing data from cervical cancer patients collected before CRT, after the first CRT fraction, and after the second fraction. Single-cell profiling revealed a significant enrichment of aNK cells following CRT. Differential gene expression and pathway enrichment analyses demonstrated that CRT-associated aNK cells exhibit enhanced virus-defending programs with increased cytotoxicity. Among the differentially expressed genes, the transcription factor PRDM1 was consistently and robustly upregulated in aNK cells after both the first and second rounds of CRT. To investigate the functional role of PRDM1, we applied in silico perturbation analyses using scTenifoldKnk and CellOracle. Virtual knockout of PRDM1 resulted in a marked attenuation of effector programs and disruption of metabolic networks in aNK cells. Moreover, PRDM1 perturbation altered inferred cellular trajectories, reversing the progression toward the aNK cell state, suggesting a requirement for PRDM1 in maintaining aNK identity and functional maturation within the CRT-conditioned tumor microenvironment. Together, these findings identify PRDM1 as a key regulatory factor associated with the enrichment, functional activation, and trajectory stabilization of aNK cells following CRT in cervical cancer, providing insight into innate immune remodeling during CRT and highlighting PRDM1 as a potential target for enhancing radiotherapy-induced antitumor immunity.

Autophagy, a key lysosomal degradation pathway regulating metabolic adaptation in cancer, plays fundamental roles in both the tumor and host stromal compartments during cancer progression. An important unanswered question is whether and how autophagy in specific host stromal elements, such as endothelial cells, influences metastasis. Here, we scrutinize how the genetic loss of autophagy in endothelial cells impacts primary tumor progression and metastasis in the Polyoma Middle T (PyMT) model of luminal B breast cancer. In both autochthonous and orthotopic mammary transplant models, PyMT primary tumor growth is significantly delayed upon endothelial cell Atg12 or Atg5 genetic deletion (Atg12 or 5 ECKO), which correlates with increased tumor cell apoptosis and HIF1 activation. In contrast, PyMT-bearing Atg12 ECKO mice exhibit increased metastasis, as well as higher rates of primary tumor and lung metastatic recurrence following surgical resection of PyMT primary tumors. Experimental metastasis assays further corroborate that loss of endothelial cell autophagy in Atg12 ECKO host animals promotes PyMT metastatic colonization and outgrowth, resulting in increased lung metastases compared to controls. Similarly, in the Rat Insulin Promoter T antigen pancreatic neuroendocrine tumor (RT2-PNET) model, endothelial cell deletion of Atg12 promotes liver micro-metastases. Taken together, these results from distinct preclinical cancer models reveal that endothelial cell autophagy suppresses metastatic seeding and progression and broach that autophagy inhibition in host endothelial cells may adversely influence the efficacy of systemic autophagy-lysosomal pathway inhibition in the clinical oncology setting.

The TGF-{beta} signaling pathway has both tumor-suppressing and metastasis-promoting effects in cancer. However, the molecular determinants governing this switch remain unclear. Here, we explored the miR-16-1-3p/MDM2/p53 axis as a critical conductor of the TGF-{beta}-Smad pathway in osteosarcoma. Although miR-16-1-3p overexpression by itself markedly reduces proliferative and clonogenic potential of U2OS cells, when paired with TGF-{beta} treatment, it significantly increases arrest cells in G1 phase and nearly extinguishing the growth capability of these cells. MiR-16-1-3p overexpression inhibited TGF-induced actin remodeling and EMT featuring, significantly decreasing vimentin levels. TGF-{beta} enhances both 2D and 3D migration, but miR-16-1-3p overexpression, alone or with TGF-{beta}, strongly counteracts its pro-migratory effects. MiR-16-1-3p restored p53 stability by targeting MDM2, redirecting TGF-{beta}-Smad signaling toward p21 activation and proliferation inhibition while attenuating its EMT-promoting capacity. Administration of TGF-{beta} together with miR-16-1-3p dramatically increases the sensitivity of wild-type U2OS cells to cisplatin, exceeding that of TGF-{beta} therapy alone by more than an order of magnitude. Administering TGF-{beta} and miR-16-1-3p together significantly reduces the tumor nodule volume and Ki67 expression, while effectively eradicates metastases in the chicken chorioallantoic membrane (CAM) in vivo model. For the first time, our research demonstrates that miR-16-1-3p shifts TGF-{beta}1 signaling from a facilitator of metastasis to a promoter of anti-growth effects through MDM2 inhibition and p53 stabilization, effectively reducing the self-renewal and invasiveness of cancer stem cells in human osteosarcoma model. This process preserves TGF-{beta}s tumor-suppressive role while limiting its associated cancer risks.

Stimulator of interferon genes (STING) agonists and derivative molecules have been extensively developed for tumor immunotherapy. However, systemic exposure toxicity risks have constrained clinical trial progression and even threatened patient lives. Currently, systematic toxicity assessments for STING agonists remain lacking, with the mode of action for major organ injury yet to be elucidated. Here, we focused on STING agonist-induced lung injury, revealing that systemic administration of STING agonists caused pulmonary hemorrhage, inflammatory alterations, and respiratory dysfunction. Through single-cell RNA sequencing and immune deletion studies, we found that lung endothelial cells could be stimulated by STING agonists and then secreted chemokines and IL-15 to recruit and activate NK cells. NK cells could induce endothelial cell apoptosis via IFN-{gamma}. Tbx21+ NK subpopulations, which activated by endothelial cells, could produce chemokines to recruit neutrophils. Neutrophils secreted IL-1{beta} through positive feedback pathways and form neutrophil extracellular traps during lung injury. This study elucidates the critical role of the endothelial cell-NK cell-neutrophil axis in mediating STING agonist-associated pneumonia, offering insights for developing intervention strategies for STING agonist toxicity.

As potent triggers of innate immunity, STING agonists hold promise as active immunotherapeutic agents for cancer treatment. Second-generation STING agonists, suitable for systemic delivery, are being investigated in preclinical research and have entered clinical trials. Here, the novel synthetic STING agonist, BI-1703880 (STINGa), which was designed for intravenous delivery, was investigated for anti-tumour and immunological effects. We show that STINGa activates the STING pathway and results in a transient and dose-dependent upregulation and secretion of interferons and proinflammatory cytokines in vitro and in vivo. We show that intravenous administration of repeated dosing with low-dose STINGa is well tolerated. We report that radiotherapy (RT) and STING agonism synergizes to generate innate immune cell and CD8+ T cell responses that control tumour growth. Anti-tumour activity induced by combined RT / STINGa was reduced in mice lacking a functional immune system. RT / STINGa combination treatment also initiated development of protective immune memory. RT / STINGa upregulated PD-L1, PD-1 and CTLA-4 in the tumour microenvironment. Our findings show that combining RT / STINGa with immune checkpoint inhibitors further increases therapeutic benefit. Our data confirm STING as a therapeutic target in cancer and support the clinical development of BI-1703880 STING agonist, thereby suggesting radiotherapy as a potential combination for enhancing anti-tumour efficacy.

Hypoxic tumour cells are resistant to many forms of cancer therapy, particularly radiotherapy. Hypoxia-activated prodrugs (HAPs) can potentially address this problem through selective release of drugs ( effectors) in oxygen-deficient microenvironments, via metabolic reduction of a nitro(hetero)aromatic trigger moiety. While many such HAPs show marked selectivity for hypoxia in cell culture, none have yet been approved for clinical use. Here, we report HAPs that release a novel inhibitor of the DNA repair enzyme DNA-dependent protein kinase (DNA-PK) which, like hypoxia, is a major contributor to radioresistance. These ether-linked HAPs provide hypoxia-dependent radiosensitisation in cell culture, but in mice systemic generation of the DNA-PK inhibitor is observed. Using in vitro hepatic metabolism models we demonstrate hypoxia-independent metabolic activation of HAP 4 via oxidation of its linker, which is mediated exclusively by CYP3A. We extend this finding to HAPs with other triggers, linkers and effectors. The clinically used CYP3A-specific inhibitor ritonavir suppressed hepatic metabolism of 4 under oxia without interfering with its hypoxia-dependent activation. In mice, ritonavir markedly enhanced oral bioavailability of the HAP, suppressed systemic formation of the DNA-PK inhibitor, and selectively radiosensitised HCT116 tumours but not the gastrointestinal tract in the radiation field. This combination offers the prospect of increasing the therapeutic ratio of DNA-PK inhibitor-mediated radiosensitisation in patients.

The pivotal role of tumor infiltrating myeloid cells in lung cancer composition and response to therapy is universally recognized. Nevertheless, their main cradle being the bone marrow (BM), remains vastly understudied owing to the spatiotemporal complexity of hematopoiesis and its hard to access anatomical location. Therefore, the BM niche of lung cancer subjects remains understudied which is why we integrated transcriptional and translational single-cell profiling, ELISA and two-photon microscopy to characterize the medullary hematopoietic compartment in orthotopic lung cancer-bearing mice with validation in human non-small cell lung cancer (NSCLC) samples. In brief we found that lung cancer remotely alters the entire hematopoietic process resulting in higher levels of hematopoietic stem cells (HSCs), myeloid and lymphoid multipotent progenitors (MPPs) and downstream predominance of Granulocyte Monocyte Progenitors (GMP), early Granulocyte Progenitors (GP) and Common Monocyte Progenitors (cMoP) at the expense of mature neutrophils and B cells. Furthermore, a significant increase in the expression and secretion of S100A9 and Lipocalin-2 (LCN2), was characteristic across the entire hematopoietic trajectory in lung cancer-bearing mice and patients. In vivo inhibition of S100A9 with Tasquinimod reduced tumor growth, irrespective of its combination with immunotherapy. In addition, it altered the secretion profile of S100A9 but also LCN2 in the BM, suggesting that S100A9 serves as an upstream regulator of LCN2 and holds therapeutic premise to treat immunotherapy refractory lung cancer.

Adoptive cell therapy based on Natural Killer (NK) cells holds great promise for the treatment of cancer. For all approaches aiming at utilizing NK cells in immunotherapy, efficient ex vivo expansion technologies for the generation on of cytotoxic NK cells are a prerequisite for clinical translation. In this study, a novel multifunctional fusion protein consisting of a CD20-directed Fab-fragment, an agonistic anti-4-1BB single-chain Fragment variable (scFv), the Sushi domain of the interleukin (IL)-15 receptor and human IL-15 was generated. This molecule triggered strong NK cell expansion when bound to co-cultivated autologous B cells, due to trans-presentation of IL-15 and binding to 4-1BB/CD137. Expansion rates of up to 7,500-fold were achieved and the NK cells showed high cytotoxic capacity against a panel of tumor cell lines representing various tumor entities. Importantly, the activated NK cells did not show cytolytic activity against non-malignant B cells indicating that NK cells amplified by our novel approach were still physiologically regulated. The cytotoxic activity of the expanded NK cells was further enhanced by combination with therapeutic antibodies. Our molecule was additionally able to trigger efficient proliferation of NK cells from cord blood as well as multiple myeloma (MM) and acute myeloid leukemia (AML) patients. In conclusion, our novel platform technology provides ex vivo expansion of NK cells by using a single multifunctional fusion protein and may be well-suited for the development of NK cell-based immunotherapies. Key pointsA novel fusion protein that enables NK cell expansion from different sources including peripheral blood, bone marrow and cord blood

Oncolytic virotherapy exploits viruses to selectively infect and destroy cancer cells while sparing normal tissues and represents a promising strategy in oncology. Human adenovirus type 5 (HAd5), although widely used, shows limited clinical efficacy due to high levels of preexisting immunity and suboptimal tumor selectivity. In this study, we evaluated novel gorilla-derived adenoviruses (GRAd) as alternative oncolytic vectors. Two distinct GRAd groups, GRAdBs and GRAdCs, were characterized for replication and cytopathic activity. GRAd25 (GRAdB group) exhibited robust replication in both tumor and normal cells, whereas GRAd32 (GRAdC group) demonstrated selective replication in tumor cells. To broaden tumor tropism while preserving selectivity, we generated a chimeric GRAd32 vector, GRAd32Fk25, by replacing its native fiber knob with that of GRAd25, potentially shifting receptor usage from CAR to CD46, which is more abundantly expressed in tumor cells. The vector was further armed with a therapeutic antibody by inserting the coding sequence for the single-chain Fc form (scFv-Fc) of EV20, a humanized anti-HER3 antibody, under endogenous viral regulatory control. In vitro analyses showed that GRAd32Fk25 maintained tumor-restricted replication and produced functional EV20 capable of binding HER3 and inhibiting downstream PI3K/Akt signaling. These results indicate that engineered GRAd vectors, exemplified by GRAd32Fk25 armed with EV20, provide a selective and versatile platform for oncolytic virotherapy with potential advantages over HAd5-based approaches.

Radiotherapy (RT) transforms tumour tissues into in situ vaccines that trigger antitumor immunity. Immunogenicity depends on how RT is delivered, since heterogeneous RT (spatially fractionated RT, SFRT) elicits more prominent responses than the conventional homogenous one. However, this phenomenon cannot be clinically harnessed, unless the relevant pathways are identified. To gain insights, we developed a hybrid dry-lab/wet-lab approach that integrates systems-level immune phenotypes established by homogenous or heterogenous RT (SFRT) with the transcriptomic profiling of irradiated tumors. By further combining feature extraction with machine-learning, including multilayer perceptron modelling, we ranked predictors of immune infiltration and patient survivability for each RT type. We found that conventional RT induces coordinated upregulation of cytosolic sensors of RNA viruses (OASes and RIG I-like receptors) along with ERV RNAs predominately 400-800 base-pairs long, which might serve as their ligands. For schemes establishing abscopal effects, a coordinated upregulation of the OAS sensors and shared ERV transcripts was observed in both irradiated and distant tumours. Compared to homogenous RT, SFRT triggered earlier and stronger activation of OAS signaling along with NK cell responses. Overall, we show a co-involvement of tumour cell-intrinsic ERVs and their cytosolic RNA sensors in RT-induced antitumor immunity. This key finding could guide mechanistic studies and future precision oncology.

The central nervous system (CNS) is a common site of metastatic spread for both non-small cell and small cell lung cancer, yet the therapeutic strategies to prevent and decrease lung cancer brain metastases remain limited. Tyrosine kinase inhibitors have shown promising results in increasing the overall response in brain metastases, owing to their brain penetrance and increased effectiveness; however, their use is limited to the small group of tumors carrying specific oncogenic drivers. Among these, inhibitors with activity against neurotrophic tyrosine receptor kinases (NTRKs) are showing promising effects in reducing CNS metastases in cancers driven by gene rearrangements of these drugs targets. However, wild-type NTRKs are susceptible to activation by their canonical ligands, which are expressed throughout the brain metastatic niche and can, in a paracrine manner, activate NTRK function in cancer cells. Here we show that NTRKs are expressed in primary tumors, brain metastases, and lung cancer cells with various driver mutations expressing wild-type NTRK2 (WT-TrkB). We demonstrate that WT-TrkB activates downstream signaling and proliferation in response to exogenous BDNF and conditioned media from reactive astrocytes known to secrete BDNF in the brain niche. Importantly, the FDA-approved NTRK inhibitor entrectinib blocked BDNF and astrocyte-induced survival pathways in multiple lung cancer cell lines, decreased their proliferation in vitro, and effectively prevented brain metastatic colonization and progression in vivo without significant effects on extracranial disease. Thus, these studies suggest that brain-dependent activation of NTRK is critical for brain metastases of WT-NTRK+ lung cancers, and therefore, NTRK inhibitors can be used to target non-fusion NTRK function to prevent or decrease brain metastases. SIGNIFICANCEThese studies demonstrate that NTRK wild-type receptors are important drivers of brain metastatic colonization and progression in different subtypes of lung cancer, independent of their driver alterations. Thus, they provide rationale to expand the use of FDA-approved NTRK inhibitors with brain penetrance for the prevention of CNS metastases.

BackgroundImmune checkpoint inhibition has transformed cancer therapy; however, many patients fail to respond to single-agent blockade, and combination strategies are often limited by toxicity. Central nervous system tumors exploit multiple immunosuppressive pathways, including the CD200 and PD-1/PD-L1 axis to evade anti-tumor immunity and support tumor aggressiveness. MethodsWe investigated ARL200, a peptide ligand targeting the CD200 activation receptor (CD200AR) using in vitro immune assays, murine syngeneic tumor models, phosphoproteomics, and correlative studies from a first-in-human trial in recurrent glioblastoma. ResultsARL200 exposure activated DAP10/12-dependent signaling and downregulated multiple inhibitory immune checkpoint receptors, including CD200R1, PD-1, and CTLA-4, and checkpoint ligands, CD200 protein and PD-L1, through suppression of the JAK1/3-SHP-STAT-IKK/{beta}-NF{kappa}B pathway. Distinct ARL200 variant peptides elicited unique immune responses. In patients with recurrent glioblastoma, ARL200 treatment was associated with immune activation, reduced inhibitory checkpoint expression, and evidence of antigen-specific memory responses without treatment-related toxicity. ConclusionsTargeting CD200AR enables coordinated modulation of multiple immune checkpoints with a single agent, representing a next-generation immunotherapeutic strategy opening a new pathway for treating aggressive malignancies. Key PointsO_LIARL200 elicits an active immune response for the development of a potent and durable anti-tumor response C_LIO_LIARL200 abolishes the suppressive effects of multiple immune checkpoint blockades C_LIO_LIDifferent ARL200 sequences drive alternative immune responses. C_LI Importance of the StudyTumors exploit multiple immune checkpoint pathways to suppress antitumor immunity, particularly within the immunosuppressive microenvironment of the central nervous system. Current immune checkpoint inhibitors often require combination therapy to achieve clinical efficacy, frequently at the cost of increased toxicity. In this study, we demonstrate that targeting the CD200 activation receptor (CD200AR) with a peptide ligand provides a novel strategy to simultaneously downregulate multiple inhibitory immune checkpoints, including CD200R1, PD-1, PD-L1, and CTLA-4, through a shared intracellular signaling pathway. ARL200 engagement activates DAP10/12-dependent signaling while suppressing the JAK1/3-SHP-STAT-IKK/{beta}-NF{kappa}B axis, thereby overriding tumor-mediated immunosuppression. Importantly, this multi-checkpoint modulation is achieved with a single therapeutic agent and translates to immune activation and clinical responses in patients with recurrent glioblastoma, with minimal treatment-related toxicity. These findings establish CD200AR targeting as a next-generation immunotherapeutic approach with the potential to improve the safety and efficacy of immune-based therapies for aggressive CNS malignancies. Graphical Abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=179 SRC="FIGDIR/small/26345679v1_ufig1.gif" ALT="Figure 1"> View larger version (80K): org.highwire.dtl.DTLVardef@17a5010org.highwire.dtl.DTLVardef@11e67eborg.highwire.dtl.DTLVardef@1387c07org.highwire.dtl.DTLVardef@156d418_HPS_FORMAT_FIGEXP M_FIG C_FIG

Patients with invasive lobular carcinoma of the breast (ILC) are at high risk of long-term recurrence and metastatic progression with poor prognoses due to delayed detection and treatment-refractory disease. Unfortunately, few models are available to investigate metastatic ILC (mILC) and understand the unique metastatic patterns and phenotypes, including abdominal metastases, leptomeningeal disease, and mixed osteosclerotic/lytic bone metastases. Therefore, we expanded upon the previously established mammary intraductal (MIND) cell line xenograft model by supplementing mice with low-dose estradiol to promote disease progression. We observed spontaneous multi-organ spread from the mammary gland to common and mILC-specific tissues, with micro-metastatic disease as early as 12 weeks post-engraftment and macro-metastatic disease in 24-30 weeks, without the need for primary tumor resection. Primary and metastatic tumors remain highly endocrine responsive, allowing for the evaluation of novel therapeutics in the setting of disseminated metastasis. Derivative cell lines were isolated from various metastatic lesions, a total of 13 derivates from 7 sites across three hosts, and were found to have shared gene expression changes related to metabolism and intercellular signaling. Focusing on bone-derived variant cells as bone is the most common site for mILC to present, we found that bone-derived variant lines maintain multi-organ metastatic potential upon rechallenge by MIND or intratibial injection, despite increased aggressiveness and maintained endocrine response. Notably, bone lesions from either challenge route showed mixed osteosclerotic/lytic features characteristic to clinical ILC. Accordingly, we found that conditioned medium from ILC cells and the mILC bone-derived variants induce osteoblast differentiation and suppressed osteoclast differentiation in vitro, consistent with their effect on bone remodeling in vivo and in clinical disease. Together, the models developed herein can be utilized to understand the unique metastatic processes of mILC, and to investigate new therapeutic combinations in the setting of endocrine-responsive primary and metastatic ILC.

Constitutively active KRAS mutations are highly prevalent in lung cancers, but the direct role of its downstream phosphatidylinositol 3-kinase (PI3K) pathway in tumor progression remains unclear. A previous study established the requirement for PIK3CA, the alpha catalytic isoform, in lung tumor development in mouse models with an intact Trp53 tumor suppressor. In this study, we further investigated the requirement for PIK3CA for tumor growth both in vitro and in vivo. We first generated a "KPA" cell line by genetically deleting Pik3ca from a murine lung adenocarcinoma "KP" cell line harboring oncogenic KrasG12D and lacking Trp53. We found that Pik3ca is not required for cell survival and growth in vitro, even under anchorage-independent conditions but reduced the growth rate by 20%. We next orthotopically implanted KP and KPA cells into syngeneic mice and found that PIK3CA is absolutely required for tumor progression, even in the absence of Trp53. Implantation of KP cells, or a "KPS" cell line lacking the Stk11 gene, led to rapid tumor growth and death of all host animals. In contrast, mice implanted with KPA cells all survived with no detectable lung tumors. The gene expression profiles from cultured cell lines suggest KPA cells may be vulnerable to oxidative stress. Indeed, we found KPA cells were more sensitive to hydrogen peroxide and diethyl maleate-induced oxidative stress as compared to KP and KPS cells. Together, these results demonstrate that PIK3CA is not required for lung cancer cell growth induced by mutant KRAS in vitro but is critically needed for in vivo progression and growth.

Cytotoxic T cells (CTL) are crucial for adaptive immunity that leads to prolonged survival and potential cures for cancer. Recent clinical data has shown that pharmacological inhibition of SUMOylation (SUMOi) profoundly modifies tumor microenvironment (TME) and activates CTL, although the mechanism is not well described. In this study, we found that T cell specific knock out (KO) of the most dominant SUMO paralog, Sumo2/SUMO2, in both mouse and human CD8+ T cells significantly enhanced CD8+ T cell activation that is independent of the known mechanism - inducing type I IFN (IFN-I) expression by myeloid cells. Sumo2/SUMO2 KO in CD8+ T cells increased chromatin accessibility for transcription factors BATF, JunB, ATF3, FRA1, FRA2, and AP1 that are known to promote T cell activation and proliferation. Using antigen-specific T cell models, OT1 and Chimeric Antigen Receptor (CAR)-T cells, we found that Sumo2 KO CD8+ T cells had significantly higher tumor infiltration as revealed by flow cytometry, immuno-fluorescence (IF) staining, and single nuclei RNA-sequencing (snRNA-seq) and conferred greater tumor growth inhibition than wildtype (WT) control T cells. snRNA-seq also revealed Sumo2 KO CD8+ T cells increased the expression of Tumor Necrosis Factor-Related Apoptosis-inducing Ligand (TRAIL), induced apoptosis genes in tumor cells and activated IFN-I and IFN-{gamma} responsive genes in all cell types in the TME. These findings elucidate a novel mechanism regarding how SUMOylation can directly control CTL activation and tumor infiltration that activate anti-tumor immunity in the TME. SUMO2 KO can also be a potential strategy to enhance adoptive T cell therapies of solid tumors by enhancing their activity, tumor infiltration and their ability to after the TME.

The extensive expression of STING in patients with non - small cell lung cancer (NSCLC) is closely associated with overall survival and other factors. Activation of the STING pathway can suppress NSCLC. However, the clinical translation of STING agonists remains hindered by challenges such as off-target effects, metabolic instability, and suboptimal pharmacokinetics. In this study, we engineered two oncolytic adenoviruses (OAds), OAd-HcGAS and OAd-McGAS, expressing human or murine cGAS, respectively, using an Ad5/3 chimeric adenovirus platform under regulation by the hTERT promoter to evaluatewhether OVs carrying the cGAS gene are capable of specifically activating the STING pathway within tumors and enhancing the anti - tumor efficacy of OVs both in vitro and in vivo.In vitro, OAd-HcGAS exhibited robust replication and potent cytolytic activity in tumor cells. It activated the STING-TBK1-IRF3 signaling axis, triggering a strong type I interferon (IFN-I) and pro-inflammatory cytokine response without compromising viral replication. In a murine Lewis lung carcinoma allograft model, intratumoral (i.t.) administration of OAd-McGAS led to substantial cGAS expression and consequential activation of the STING pathway. Moreover, the combination with anti-PD-L1 therapy resulted in tumor regression in over half of the cases. Notably, this armed oncolytic virus strategy enhanced the activation and infiltration of multiple immune cell populations. Collectively, these findings establish cGAS-expressing oncolytic adenoviruses as a novel and effective therapeutic strategy for lung cancer treatment. Graphical AbstractViral replication & Transgene expression & Cancer treatment

Cancer heterogeneity is traditionally attributed to multiple parallel signaling pathways. This belief is challenged here by proposing the ER/PR axis as the dominant pathway underlying the full spectrum of breast cancer. Absolutely quantitated ER, PR, Her2 and Ki67 protein levels were accumulated over 8 years from 1652 specimens collected non-selectively and measured with Quantitative Dot Blot (QDB) method over time. Cox analysis showed ER and Ki67 as independent adverse prognostic factors while PR was an independent favorable factor statistically. Their optimized stratification framework demonstrated that prognosis across all clinical subtypes was predominantly aligned along the ER/PR axis rather than being subtype-specific, including repeated identification of a subgroup with near-perfect 10-year survival probability from three independent cohorts to be proposed as the biological basis of the ultra-safe group in MINDACT trial. A parsimonious model is proposed where the ER/PR signaling hierarchy supersedes current prevailing clinical subtyping, with its balance essential for survival until ER levels become uncontrollable. This concept of pathway hierarchy may also exist in other major cancer types, and cannot be addressed without clinical epidemiology.

tRNA-derived fragments (tRFs) are relatively recently discovered class of small RNAs implicated in gene-regulatory processes in diverse biological contexts but there have been very few reports of a clear phenotypic role of these small RNAs in cancer progression. By analyzing small RNA-seq data from The Cancer Genome Atlas (TCGA), we found that high expression of three 3' tRFs (tRF-3a), tRF-3009a, tRF-3021a or tRF-3030a, is significantly associated with poor overall survival in low-grade glioma (LGG). In glioblastoma cells, tRF-3009a, tRF-3021a and tRF-3030a enhance cell invasion and migration but tRF-3021a was uniquely required for cell proliferation and suppression of apoptosis. Interestingly, tRF-3021a knockdown decreases global protein synthesis prior to and independent of apoptosis. These data indicate that tRF-3021a supports glioma cell survival and particularly protein synthesis while promoting cellular invasion and migration. Given its association with poor outcome in LGG patients, tRF-3021a represents a promising biomarker and potential therapeutic target in gliomas and these results provide a foundation for future studies to define its molecular interactors and downstream pathways controlling protein synthesis and apoptosis in cancer cells. ImplicationtRF-3021a promotes malignant glioma phenotypes, sustains global protein synthesis and prevents spontaneous apoptosis, motivating efforts to evaluate it as a biomarker and therapeutic target.