Invasive growth of brain metastases is linked to CHI3L1 release from pSTAT3-positive astrocytes.

BACKGROUND: Compared to minimally invasive brain metastases (MI BrM), highly invasive (HI) lesions form abundant contacts with cells in the peritumoral brain parenchyma and are associated with poor prognosis. Reactive astrocytes (RAs) labeled by phosphorylated STAT3 (pSTAT3) have recently emerged as a promising therapeutic target for BrM. Here, we explore whether the BrM invasion pattern is influenced by pSTAT3+ RAs and may serve as a predictive biomarker for STAT3 inhibition. METHODS: We used immunohistochemistry to identify pSTAT3+ RAs in HI and MI human and patient-derived xenograft (PDX) BrM. Using PDX, syngeneic, and transgenic mouse models of HI and MI BrM, we assessed how pharmacological STAT3 inhibition or RA-specific STAT3 genetic ablation affected BrM growth in vivo. Cancer cell invasion was modeled in vitro using a brain slice-tumor co-culture assay. We performed single-cell RNA sequencing of human BrM and adjacent brain tissue. RESULTS: RAs expressing pSTAT3 are situated at the brain-tumor interface and drive BrM invasive growth. HI BrM invasion pattern was associated with delayed growth in the context of STAT3 inhibition or genetic ablation. We demonstrate that pSTAT3+ RAs secrete Chitinase 3-like-1 (CHI3L1), which is a known STAT3 transcriptional target. Furthermore, single-cell RNA sequencing identified CHI3L1-expressing RAs in human HI BrM. STAT3 activation, or recombinant CHI3L1 alone, induced cancer cell invasion into the brain parenchyma using a brain slice-tumor plug co-culture assay. CONCLUSIONS: Together, these data reveal that pSTAT3+ RA-derived CHI3L1 is associated with BrM invasion, implicating STAT3 and CHI3L1 as clinically relevant therapeutic targets for the treatment of HI BrM.

The tumor-derived cytokine Chi3l1 induces neutrophil extracellular traps that promote T cell exclusion in triple-negative breast cancer.

In triple-negative breast cancer (TNBC), stromal restriction of CD8+ T cells associates with poor clinical outcomes and lack of responsiveness to immune-checkpoint blockade (ICB). To identify mediators of T cell stromal restriction, we profiled murine breast tumors lacking the transcription factor Stat3, which is commonly hyperactive in breast cancers and promotes an immunosuppressive tumor microenvironment. Expression of the cytokine Chi3l1 was decreased in Stat3-/- tumors. CHI3L1 expression was elevated in human TNBCs and other solid tumors exhibiting T cell stromal restriction. Chi3l1 ablation in the polyoma virus middle T (PyMT) breast cancer model generated an anti-tumor immune response and delayed mammary tumor onset. These effects were associated with increased T cell tumor infiltration and improved response to ICB. Mechanistically, Chi3l1 promoted neutrophil recruitment and neutrophil extracellular trap formation, which blocked T cell infiltration. Our findings provide insight into the mechanism underlying stromal restriction of CD8+ T cells and suggest that targeting Chi3l1 may promote anti-tumor immunity in various tumor types.

Ezh2 promotes mammary tumor initiation through epigenetic regulation of the Wnt and mTORC1 signaling pathways.

The regulation of gene expression through histone posttranslational modifications plays a crucial role in breast cancer progression. However, the molecular mechanisms underlying the contribution of histone modification to tumor initiation remain unclear. To gain a deeper understanding of the role of the histone modifier Enhancer of Zeste homology 2 (Ezh2) in the early stages of mammary tumor progression, we employed an inducible mammary organoid system bearing conditional Ezh2 alleles that faithfully recapitulates key events of luminal B breast cancer initiation. We showed that the loss of Ezh2 severely impairs oncogene-induced organoid growth, with Ezh2-deficient organoids maintaining a polarized epithelial phenotype. Transcriptomic profiling showed that Ezh2-deficient mammary epithelial cells up-regulated the expression of negative regulators of Wnt signaling and down-regulated genes involved in mTORC1 (mechanistic target of rapamycin complex 1) signaling. We identified Sfrp1, a Wnt signaling suppressor, as an Ezh2 target gene that is derepressed and expressed in Ezh2-deficient epithelium. Furthermore, an analysis of breast cancer data revealed that Sfrp1 expression was associated with favorable clinical outcomes in luminal B breast cancer patients. Finally, we confirmed that targeting Ezh2 impairs mTORC1 activity through an indirect mechanism that up-regulates the expression of the tumor suppressor Pten. These findings indicate that Ezh2 integrates the mTORC1 and Wnt signaling pathways during early mammary tumor progression, arguing that inhibiting Ezh2 or therapeutically targeting Ezh2-dependent programs could be beneficial for the treatment of early-stage luminal B breast cancer.

Adoption Of Standard Medical Deduction Increased SNAP Enrollment And Benefits In 21 Participating States.

The Supplemental Nutrition Assistance Program (SNAP) reduces food insecurity but is underused among many households. To increase SNAP participation, twenty-one states have adopted the standard medical deduction (SMD), which simplifies administrative requirements for eligible households (those with older adults or people with disabilities). However, to offset the costs of the SMD, states have reduced SNAP benefits elsewhere, raising concerns of negative spillover effects. Using national data from the period 2004-19 and a fixed-effects estimator, we found that the SMD was associated with increased SNAP participation among SMD-eligible households, in terms of aggregate household counts (20 percent) and as a share of households receiving SNAP (5 percentage points). Moreover, estimated annual SNAP benefits per state increased for SMD-eligible households but decreased (although not statistically significantly) for ineligible households. Offsetting SNAP costs may have benefited households with older adults and households with people with disabilities at the expense of others.

HER2Δ16 Engages ENPP1 to Promote an Immune-Cold Microenvironment in Breast Cancer.

The tumor-immune microenvironment (TIME) is a critical determinant of therapeutic response. However, the mechanisms regulating its modulation are not fully understood. HER2Δ16, an oncogenic splice variant of the HER2, has been implicated in breast cancer and other tumor types as a driver of tumorigenesis and metastasis. Nevertheless, the underlying mechanisms of HER2Δ16-mediated oncogenicity remain poorly understood. Here, we show that HER2∆16 expression is not exclusive to the clinically HER2+ subtype and associates with a poor clinical outcome in breast cancer. To understand how HER2 variants modulated the tumor microenvironment, we generated transgenic mouse models expressing either proto-oncogenic HER2 or HER2Δ16 in the mammary epithelium. We found that HER2∆16 tumors were immune cold, characterized by low immune infiltrate and an altered cytokine profile. Using an epithelial cell surface proteomic approach, we identified ectonucleotide pyrophosphatase/phosphodiesterase 1 (ENPP1) as a functional regulator of the immune cold microenvironment. We generated a knock-in model of HER2Δ16 under the endogenous promoter to understand the role of Enpp1 in aggressive HER2+ breast cancer. Knockdown of Enpp1 in HER2Δ16-derived tumor cells resulted in decreased tumor growth, which correlated with increased T-cell infiltration. These findings suggest that HER2Δ16-dependent Enpp1 activation associates with aggressive HER2+ breast cancer through its immune modulatory function. Our study provides a better understanding of the mechanisms underlying HER2Δ16-mediated oncogenicity and highlights ENPP1 as a potential therapeutic target in aggressive HER2+ breast cancer.

Single-cell spatial immune landscapes of primary and metastatic brain tumours.

Single-cell technologies have enabled the characterization of the tumour microenvironment at unprecedented depth and have revealed vast cellular diversity among tumour cells and their niche. Anti-tumour immunity relies on cell-cell relationships within the tumour microenvironment1,2, yet many single-cell studies lack spatial context and rely on dissociated tissues3. Here we applied imaging mass cytometry to characterize the immunological landscape of 139 high-grade glioma and 46 brain metastasis tumours from patients. Single-cell analysis of more than 1.1 million cells across 389 high-dimensional histopathology images enabled the spatial resolution of immune lineages and activation states, revealing differences in immune landscapes between primary tumours and brain metastases from diverse solid cancers. These analyses revealed cellular neighbourhoods associated with survival in patients with glioblastoma, which we leveraged to identify a unique population of myeloperoxidase (MPO)-positive macrophages associated with long-term survival. Our findings provide insight into the biology of primary and metastatic brain tumours, reinforcing the value of integrating spatial resolution to single-cell datasets to dissect the microenvironmental contexture of cancer.

Coordinated activation of c-Src and FOXM1 drives tumor cell proliferation and breast cancer progression.

Activation of the tyrosine kinase c-Src promotes breast cancer progression and poor outcomes, yet the underlying mechanisms are incompletely understood. Here, we have shown that deletion of c-Src in a genetically engineered model mimicking the luminal B molecular subtype of breast cancer abrogated the activity of forkhead box M1 (FOXM1), a master transcriptional regulator of the cell cycle. We determined that c-Src phosphorylated FOXM1 on 2 tyrosine residues to stimulate its nuclear localization and target gene expression. These included key regulators of G2/M cell-cycle progression as well as c-Src itself, forming a positive feedback loop that drove proliferation in genetically engineered and patient-derived models of luminal B-like breast cancer. Using genetic approaches and small molecules that destabilize the FOXM1 protein, we found that targeting this mechanism induced G2/M cell-cycle arrest and apoptosis, blocked tumor progression, and impaired metastasis. We identified a positive correlation between FOXM1 and c-Src expression in human breast cancer and show that the expression of FOXM1 target genes predicts poor outcomes and associates with the luminal B subtype, which responds poorly to currently approved therapies. These findings revealed a regulatory network centered on c-Src and FOXM1 that is a targetable vulnerability in aggressive luminal breast cancers.

Cognitive Impairment and Supplemental Nutrition Assistance Program Take-Up Among the Eligible Older Americans.

OBJECTIVES: Participation in the Supplemental Nutrition Assistance Program (SNAP) among eligible adults aged 60 and older is much lower than among the younger population, and rates continue to decline throughout the life course while at the same time the risk of cognitive impairment increases. Due to the high administrative burden associated with SNAP application processes, cognitive impairment may be associated with low uptake of SNAP among the low-income older adult population, particularly among more socially disadvantaged groups (females, Blacks, and those living alone). We provide new evidence that changes in cognitive functioning are associated with reductions in the probability of SNAP take-up among eligible older adults. METHODS: Using panel data from the Health and Retirement Study, we estimate linear probability fixed-effects models to assess the effect of cognitive decline on the likelihood of SNAP participation among eligible adults aged 60 and older, controlling for observed characteristics that change over time as well as individual, time, and state fixed effects. RESULTS: Reduced levels of cognitive functioning that rise to the classification of dementia were strongly associated with reductions in the probability of SNAP take-up among eligible older adults. Results were particularly salient for females and those living alone. DISCUSSION: One barrier to SNAP take-up among older adults may be cognitive impairment with the size of effect differing by gender and living arrangement. Policymakers may want to consider initiatives to increase SNAP participation among older adults, including a focus on further simplification of eligibility and recertification processes that reduce administrative burden.

Hypoxic mesenchymal stem cell-derived exosomes alleviate ulcerative colitis injury by limiting intestinal epithelial cells reactive oxygen species accumulation and DNA damage through HIF-1α.

Ulcerative colitis (UC) is an inflammatory disease with a complex pathogenic mechanism. Mounting evidence suggests that UC pathogenesis is linked to excessive production of reactive oxygen species (ROS) and cellular DNA damage. Recent studies have shown that bone mesenchymal stem cells (BMSCs) mainly exert their therapeutic effects through paracrine exosomes, and oxygen concentration is extremely important to BMSCs and exosomes. The main objective of this study was to determine whether exosomes from BMSCs under hypoxic conditions (HP-Exos) exhibit a greater therapeutic effect on UC compared to exosomes under normoxic conditions (Exos) and to resolve the mechanism of HP-Exos. We observed that hypoxia enhances the activity and migration of BMSCs and inhibits BMSC apoptosis without changing their morphological characteristics. Furthermore, HP-Exos significantly relieved UC symptoms and pathological damage. In order to further understand the mechanism of HP-Exos in UC, findings from in vivo experiments demonstrated that HP-Exos reduces ROS production, DNA damage and apoptosis in intestinal epithelial cells. As hypoxia-inducible factor 1α (HIF-1α) plays an important role in hypoxia, we knocked down HIF-1α in BMSCs. HIF-1α knockout reversed the effects of hypoxia on the activity, migration and apoptosis of BMSCs. Moreover, inhibition of HIF-1α expression also reversed the regulation of UC by HP-Exos. Therefore, we conclude that HP-Exos regulates ROS accumulation, DNA damage and immune homeostasis in intestinal epithelial cells via HIF-1α.

BMSCs improve TNBS-induced colitis in rats by inducing Treg differentiation by expressing PD-L1.

OBJECTIVES: Bone marrow-derived mesenchymal stem cells (BMSCs) show promise in treating inflammatory bowel disease. We tested if BMSCs improve Trinitro-benzene-sulfonic acid (TNBS)-induced colitis by inducing Treg differentiation by modulating programmed cell death 1 ligand 1(PD-L1). RESULTS: BMSCs were isolated and transfected with PD-L1 siRNA. Sprague-Dawley rats were randomly divided into 4 groups: normal, model, BMSC control, and PD-L1 siRNA BMSC. Colitis was induced by TNBS, except in the normal group. On d4, the BMSC control and PD-L1 siRNA BMSC groups were intravenously injected with BMSCs at a dose of 5 × 106 cells in phosphate-buffered saline (PBS; volume matched). BMSCs were later verified to have reached the colon tissue. BMSC control showed significantly better clinical symptoms and reduced histopathological colitis severity; PD-L1 siRNA BMSC group showed no difference. PD-L1 siRNA reduced: spleen and mesenteric lymph node Tregs, PD-L1, interleukin-10 (IL10), phosphate and tension homology deleted on chromosome ten (PTEN); colon p-Akt and p-mTOR were increased. CONCLUSIONS: We found that BMSCs can induce Treg differentiation by inhibiting the Akt/mTOR pathway via PD-L1; this significantly improved symptoms and pathology in our ulcerative colitis rat models.

Integrated multi-omics analysis of adverse cardiac remodeling and metabolic inflexibility upon ErbB2 and ERRα deficiency.

Functional oncogenic links between ErbB2 and ERRα in HER2+ breast cancer patients support a therapeutic benefit of co-targeted therapies. However, ErbB2 and ERRα also play key roles in heart physiology, and this approach could pose a potential liability to cardiovascular health. Herein, using integrated phosphoproteomic, transcriptomic and metabolic profiling, we uncovered molecular mechanisms associated with the adverse remodeling of cardiac functions in mice with combined attenuation of ErbB2 and ERRα activity. Genetic disruption of both effectors results in profound effects on cardiomyocyte architecture, inflammatory response and metabolism, the latter leading to a decrease in fatty acyl-carnitine species further increasing the reliance on glucose as a metabolic fuel, a hallmark of failing hearts. Furthermore, integrated omics signatures of ERRα loss-of-function and doxorubicin treatment exhibit common features of chemotherapeutic cardiotoxicity. These findings thus reveal potential cardiovascular risks in discrete combination therapies in the treatment of breast and other cancers.

COVID-19 infection with keratitis as the first clinical manifestation.

AIM: To report a case which keratitis is the first clinical manifestation of COVID-19 that occurred 3d earlier than the common COVID-19 symptoms. METHODS: Regular slit lamp examination, corneal scraping test, and chest computed tomography (CT) were performed for patients with COVID-19 infection. The ophthalmologic treatment included ganciclovir eye drop (50 mg/mL, 6 times/d). The treatment for diarrhea included Guifu Lizhong pills (TID). The antiviral therapy consisted of oseltamivir (75 mg capsule Q12H); therapy preventing bacterial infection consisted of azithromycin (250 mg tablet QD) and moxifloxacin (0.4 g tablet Q12H); and therapy for cough relief and fever prevention consisted of Chinese herbal decoction. RESULTS: A 35-year-old male suddenly suffered pain, photophobia, and tears in his right eye for one day without systemic COVID-19 symptoms. Patient was diagnosed with keratitis, which was seemingly different from common keratitis. Ganciclovir eye drop was initiated. The corneal scraping test for COVID-19 was positive. The chest CT images were abnormal confirming the diagnosis of COVID-19 infection. The antiviral and antibacterial therapies were initiated. Chinese herbal therapy was used for cough relief and fever prevention. After roughly two weeks, patient recovered from COVID-19. CONCLUSION: A new type of keratitis, atypical keratitis, is a clinical manifestation of COVID-19, and this clinical manifestation could appear 3d earlier than fever and cough. The earlier a COVID-19 clinical manifestation is identified, the earlier can a patient be directed to stay at home, and significantly fewer people would be infected.

HSPA5 Inhibitor Meliorate DSS-Induced Colitis through HSPA1A/CHIP.

Objective: Ulcerative colitis (UC) is closely related to immune response, in which Treg cells (Tregs) suppress the autoimmune response of effector T cells to maintain homeostasis. As a marker of endoplasmic reticulum stress (ERS), HSPA5 was highly expressed in the colon tissue of UC patients. This study is aimed at evaluating the therapeutic effect of HSPA5 inhibitor (HA15) on dextran sulfate sodium- (DSS-) induced ulcerative colitis in mice and explored the effect and related mechanism of HSPA5 inhibitor on the differentiation and function of Tregs. Methods: Thirty-two C57BL/6 mice were randomly divided into four groups (8 mice per group): normal control group, DSS model group, HSPA5 inhibitor (HA15) group (intraperitoneal injection), and dexamethasone (DXM) group (intraperitoneal injection). Except for the blank control group, the other groups were induced with 3% DSS for 7 days and then given corresponding intervention therapy for 7 days. Results: The disease activity index (DAI) score, colon length, histopathological changes, and scores of DSS-induced mice show that HA15 could significantly improve the degree of inflammation in ulcerative colitis. Moreover, HA15 can better inhibit the expression of HSPA5, HSPA1A, and CHIP in the colon and increase the level of FOXP3 mRNA. Finally, the content of Treg cells and the levels of IL-10 and TGF-ß1 were significantly increased, and the levels of IL-6 were significantly reduced. Conclusions: HA15 can improve the differentiation and function of Treg cells by inhibiting the HSPA1A/CHIP pathway, thereby improving ulcerative colitis. Therefore, inhibiting the expression of HSPA5 may serve as a new approach to treat ulcerative colitis.

Enhanced migration and immunoregulatory capacity of BMSCs mediated by overexpression of CXCR4 and IL-35.

Bone marrow-derived mesenchymal stem cells (BMSCs) have been widely studied for their applications in immunoregulation and tissue repair. However, the therapeutic effects of BMSCs in the body are limited, partly due to the low homing efficiency of BMSCs to affected parts. The stromal cell-derived factor 1 (SDF-1)/C-X-C chemokine receptor type 4 (CXCR4) axis is well known to play an essential role in the homing of BMSCs. Interleukin 35 (IL-35) is a newly discovered cytokine confirmed to inhibit overactivated immune function and have a good therapeutic effect on autoimmune diseases. In this study, we innovatively developed dual gene modification of BMSCs by transducing CXCR4 and IL-35 and found that the migration and immunomodulatory activity of genetically engineered BMSCs were significantly enhanced compared to their natural counterparts. These results suggest that BMSCs modified by dual overexpression of CXCR4 and IL-35 may provide a potential treatment strategy for autoimmune diseases.

PHGDH heterogeneity potentiates cancer cell dissemination and metastasis.

Cancer metastasis requires the transient activation of cellular programs enabling dissemination and seeding in distant organs1. Genetic, transcriptional and translational heterogeneity contributes to this dynamic process2,3. Metabolic heterogeneity has also been observed4, yet its role in cancer progression is less explored. Here we find that the loss of phosphoglycerate dehydrogenase (PHGDH) potentiates metastatic dissemination. Specifically, we find that heterogeneous or low PHGDH expression in primary tumours of patients with breast cancer is associated with decreased metastasis-free survival time. In mice, circulating tumour cells and early metastatic lesions are enriched with Phgdhlow cancer cells, and silencing Phgdh in primary tumours increases metastasis formation. Mechanistically, Phgdh interacts with the glycolytic enzyme phosphofructokinase, and the loss of this interaction activates the hexosamine-sialic acid pathway, which provides precursors for protein glycosylation. As a consequence, aberrant protein glycosylation occurs, including increased sialylation of integrin αvß3, which potentiates cell migration and invasion. Inhibition of sialylation counteracts the metastatic ability of Phgdhlow cancer cells. In conclusion, although the catalytic activity of PHGDH supports cancer cell proliferation, low PHGDH protein expression non-catalytically potentiates cancer dissemination and metastasis formation. Thus, the presence of PHDGH heterogeneity in primary tumours could be considered a sign of tumour aggressiveness.

Physiological expression of PI3K H1047R mutation reveals its anti-metastatic potential in ErbB2-driven breast cancer.

p110α is a catalytic subunit of phosphoinositide 3-kinase (PI3K), a major downstream effector of receptor tyrosine kinase ErbB2, that is amplified and overexpressed in 20-30% of breast cancers, 40% of which have an activating mutation in p110α. Despite the high frequency of PIK3CA gain-of-function mutations, their prognostic value is controversial. Here, we employ a knock-in transgenic strategy to restrict the expression of an activated form of ErbB2 and p110α kinase domain mutation (p110αHR) in the mammary epithelium. Physiological levels of transgene expression under the control of their endogenous promoters did not result in a major synergistic effect. However, tumors arising in ErbB2/p110αHR bi-genic strain metastasized to the lung with significantly reduced capacity compared to tumors expressing ErbB2 alone. The reduced metastasis was further associated with retention of the myoepithelial layer reminiscent of ductal carcinoma in situ (DCIS), a non-invasive stage of human breast cancer. Molecular and biochemical analyses revealed that these poorly metastatic tumors exhibited a significant decrease in phospho-myosin light chain 2 (MLC2) associated with cellular contractility and migration. Examination of human samples for MLC2 activity revealed a progressive increase in cellular contractility between non-invasive DCIS and invasive ductal carcinoma. Collectively, these data argue that p110αHR mutation attenuates metastatic behavior in the context of ErbB2-driven breast cancer.

Assessing the post-treatment therapeutic effect of tongxie in irritable bowel syndrome: A randomized controlled trial.

Diarrhea predominant irritable bowel syndrome (IBS) is a highly relapsing gastrointestinal disorder decreasing the quality of life. Existing studies indicated that the therapeutic effects maintained for a period of time after the treatments were discontinued (post-treatment therapeutic effects or PTTE). In this study, we aim to assess the PTTE of tongxie. We performed a multiple center, controlled, double blind study of patients with IBS randomized to tongxie (n = 120) or placebo (n = 120) for 4 weeks and followed up for 57 weeks. The primary outcomes were abdominal pains and stool consistency. The secondary outcomes were pain frequency and stool frequency. Tertiary outcomes were adverse effects and global overall symptom. The outcome data were collected at days 1, 2, 3, weeks 1 and 4 during the treatment and at days 1, 2, 3, until week 57 during the post-treatment. Significantly more patients receiving tongxie were clinical responders to the primary and secondary endpoints from day 1 until the end of the treatment. The positive effects of tongxie were maintained until 17-25 weeks after tongxie was discontinued. The relapse-free probabilities in the tongxie group were significantly higher than those in the placebo group (P < .001). Twenty-five weeks after the therapies were discontinued could be considered as IBS natural history. During this period, an average of 53.8-56.3% of patients (pool tongxie and placebo data together) had IBS symptoms (pain scale ≥ 3, stool consistency ≥ 5). In particular, at the end of this study (week 61), 145 (54.2%) patients had IBS symptoms. Our results provide clinical insights into efficient and cost-effective management of refractory IBS, and lend support to the IBS management that the selection of a therapy should consider both its effectiveness during treatment and its PTTE after the treatment.

Spatially mapping the immune landscape of melanoma using imaging mass cytometry.

Melanoma is an immunogenic cancer with a high response rate to immune checkpoint inhibitors (ICIs). It harbors a high mutation burden compared with other cancers and, as a result, has abundant tumor-infiltrating lymphocytes (TILs) within its microenvironment. However, understanding the complex interplay between the stroma, tumor cells, and distinct TIL subsets remains a substantial challenge in immune oncology. To properly study this interplay, quantifying spatial relationships of multiple cell types within the tumor microenvironment is crucial. To address this, we used cytometry time-of-flight (CyTOF) imaging mass cytometry (IMC) to simultaneously quantify the expression of 35 protein markers, characterizing the microenvironment of 5 benign nevi and 67 melanomas. We profiled more than 220,000 individual cells to identify melanoma, lymphocyte subsets, macrophage/monocyte, and stromal cell populations, allowing for in-depth spatial quantification of the melanoma microenvironment. We found that within pretreatment melanomas, the abundance of proliferating antigen-experienced cytotoxic T cells (CD8+CD45RO+Ki67+) and the proximity of antigen-experienced cytotoxic T cells to melanoma cells were associated with positive response to ICIs. Our study highlights the potential of multiplexed single-cell technology to quantify spatial cell-cell interactions within the tumor microenvironment to understand immune therapy responses.

Emergence of ß1 integrin-deficient breast tumours from dormancy involves both inactivation of p53 and generation of a permissive tumour microenvironment.

The molecular and cellular mechanisms underlying mammary tumour dormancy and cancer recurrence are unclear and remain to be elucidated. Here, we report that mammary epithelial-specific disruption of ß1 integrin in a murine model of Luminal B human breast cancer drastically impairs tumour growth with proliferation block, apoptosis induction and cellular senescence. ß1 integrin-deficient dormant lesions show activation of the tumour suppressor p53, and tumours that circumvent dormancy possess p53 mutation analogous to those in human disease. We further demonstrate that mammary epithelial deletion of p53 in ß1 integrin-deficient mice fully rescues tumour dormancy and bypasses cellular senescence. Additionally, recurrent ß1 integrin-deficient tumours exhibit fibrosis with increased cancer-associated fibroblast infiltration and extracellular matrix deposition, absent in fast-growing ß1 integrin/p53-deficient lesions. Taken together, these observations argue that ß1 integrin modulates p53-dependent cellular senescence resulting in tumour dormancy and that pro-tumourigenic stromal cues and intrinsic genetic mutation are required for dormancy exit.