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Chemotherapy often generates intratumoral senescent cancer cells that strongly modify the tumor microenvironment, favoring immunosuppression and tumor growth. We discovered, through an unbiased proteomics screen, that the immune checkpoint inhibitor programmed cell death 1 ligand 2 (PD-L2) is highly upregulated upon induction of senescence in different types of cancer cells. PD-L2 is not required for cells to undergo senescence, but it is critical for senescent cells to evade the immune system and persist intratumorally. Indeed, after chemotherapy, PD-L2-deficient senescent cancer cells are rapidly eliminated and tumors do not produce the senescence-associated chemokines CXCL1 and CXCL2. Accordingly, PD-L2-deficient pancreatic tumors fail to recruit myeloid-derived suppressor cells and undergo regression driven by CD8 T cells after chemotherapy. Finally, antibody-mediated blockade of PD-L2 strongly synergizes with chemotherapy causing remission of mammary tumors in mice. The combination of chemotherapy with anti-PD-L2 provides a therapeutic strategy that exploits vulnerabilities arising from therapy-induced senescence. Chaib et al. find that therapy-induced senescent cells have high programmed cell death 1 ligand 2 (PD-L2), contributing to recurrence. They show that PD-L2 blocking combined with chemotherapy is therapeutically beneficial because it reduces senescent cells and immunosuppressive cell recruitment.

The NeoRHEA was a single-arm phase 2 study that included patients with estrogen receptor positive / human epidermal factor receptor 2 negative early breast cancer that received 4 cycles of neoadjuvant palbociclib and endocrine therapy. The primary outcome was baseline biomarkers of treatment resistance and secondary outcome was post-treatment transcriptional and epigenetic changes of tumor, immune and stromal cells. E2F targets and G2M checkpoint proliferation-related genes gene sets were enriched in baseline samples from resistant patients., Downregulation of E2F targets and G2M checkpoint post treatment was observed in tumor, endothelial and T cells. Gene Set Enrichment Analyses (GSEA) based on genes residing in the differentially accessible peaks revealed similar effects,. Moreover, decreases in CD8 + CD103+ tissue-resident memory cell marker genes were observed post-treatment and validated by multiplex immunohistochemistry. Our data reveal that treatment with palbociclib and endocrine therapy diminishes adaptive anti-tumor immunity by decreasing T cell proliferation and the presence of tissue-resident memory T cells NCT03065621. The NeoRHEA trial showed that treatment with palbociclib and endocrine therapy decreases T cell proliferation and the presence of tissue-resident memory T cells. These results are important for the development of CDK4 selective inhibitors.

NOTCH signaling suppresses tumor growth and proliferation in several types of stratified epithelia. Here, we show that missense mutations in NOTCH1 and NOTCH2 found in human bladder cancers result in loss of function. In murine models, genetic ablation of the NOTCH pathway accelerated bladder tumorigenesis and promoted the formation of squamous cell carcinomas, with areas of mesenchymal features. Using bladder cancer cells, we determined that the NOTCH pathway stabilizes the epithelial phenotype through its effector HES1 and, consequently, loss of NOTCH activity favors the process of epithelial-mesenchymal transition. Evaluation of human bladder cancer samples revealed that tumors with low levels of HES1 present mesenchymal features and are more aggressive. Together, our results indicate that NOTCH serves as a tumor suppressor in the bladder and that loss of this pathway promotes mesenchymal and invasive features.

Genetic aberrations responsible for soft-tissue sarcoma formation in adults are largely unknown, with targeted therapies sorely needed for this complex and heterogeneous family of diseases. Here we report that that the Hippo pathway is deregulated in many soft-tissue sarcomas, resulting in elevated expression of the effector molecule Yes-Associated Protein (YAP). Based on data gathered from human sarcoma patients, a novel autochthonous mouse model, and mechanistic analyses, we determined that YAP-dependent expression of the transcription factor forkhead box M1 (FOXM1) is necessary for cell proliferation/tumorigenesis in a subset of soft-tissue sarcomas. Notably, FOXM1 directly interacts with the YAP transcriptional complex via TEAD1, resulting in coregulation of numerous critical pro-proliferation targets that enhance sarcoma progression. Finally, pharmacologic inhibition of FOXM1 decreases tumor size in vivo, making FOXM1 an attractive therapeutic target for the treatment of some sarcoma subtypes.

Tuberous sclerosis complex (TSC) is a tumor suppressor gene syndrome characterized by seizures, mental retardation, autism, and tumors of the brain, kidney, heart, retina, and skin. TSC is caused by mutations in either TSC1 or TSC2, both of which are tumor suppressor genes. Hamartin, the protein product of TSC1, was found to interact with the ezrin-radixin-moesin family of cytoskeletal proteins and to activate the small GTPase Rho. To determine whether tuberin, the TSC2 product, can also activate Rho, we stably expressed full-length human tuberin in two cell types: MDCK cells and ELT3 cells. ELT3 cells lack endogenous tuberin expression. We found that expression of human tuberin in both MDCK and ELT3 cells was associated with an increase in the amount of Rho-GTP, but not in Rac1-GTP or cdc42-GTP. Tuberin expression increased cell adhesion in both cell types, and decreased chemotactic cell migration in ELT3 cells. In MDCK cells, there was a decrease in the amount of total Focal Adhesion Kinase (FAK) and an increase in the fraction of phosphorylated FAK. These findings demonstrate for the first time that tuberin activates Rho and regulates cell adhesion and migration. Pathways involving Rho activation may have relevance to the clinical manifestations of TSC, including pulmonary lymphangioleiomyomatosis.

Despite significant efforts to improve pancreatic ductal adenocarcinoma (PDAC) clinical outcomes, overall survival remains dismal. The poor response to current therapies is partly due to the existence of pancreatic cancer stem cells (PaCSCs), which are efficient drivers of PDAC tumorigenesis, metastasis and relapse. To find new therapeutic agents that could efficiently kill PaCSCs, we screened a chemical library of 680 compounds for candidate small molecules with anti-CSC activity, and identified two compounds of a specific chemical series with potent activity in vitro and in vivo against patient-derived xenograft (PDX) cultures. The anti-CSC mechanism of action of this specific chemical series was found to rely on induction of lysosomal membrane permeabilization (LMP), which is likely associated with the increased lysosomal mass observed in PaCSCs. Using the well characterized LMP-inducer siramesine as a tool molecule, we show elimination of the PaCSC population in mice implanted with tumors from two PDX models. Collectively, our approach identified lysosomal disruption as a promising anti-CSC therapeutic strategy for PDAC.

Summary Exceptional longevity (EL) is a rare phenotype that can cluster in families, and co‐segregation of genetic variation in these families may point to candidate genes that could contribute to extended lifespan. In this study, for the first time, we have sequenced a total of seven exomes from exceptionally long‐lived siblings (probands ≥ 103 years and at least one sibling ≥ 97 years) that come from three separate families. We have focused on rare functional variants (RFVs) which have ≤ 1% minor allele frequency according to databases and that are likely to alter gene product function. Based on this, we have identified one candidate longevity gene carrying RFVs in all three families, APOB. Interestingly, APOB is a component of lipoprotein particles together with APOE, and variants in the genes encoding these two proteins have been previously associated with human longevity. Analysis of nonfamilial EL cases showed a trend, without reaching statistical significance, toward enrichment of APOB RFVs. We have also identified candidate longevity genes shared between two families (5–13) or within individual families (66–156 genes). Some of these genes have been previously linked to longevity in model organisms, such as PPARGC1A, NRG1, RAD52, RAD51, NCOR1, and ADCY5 genes. This work provides an initial catalog of genes that could contribute to exceptional familial longevity.

Birt–Hogg–Dubé (BHD) syndrome is a tumor-suppressor gene disorder characterized by skin tumors, cystic lung disease and renal cell carcinoma. Very little is known about the molecular pathogenesis of BHD. Clinical similarities between BHD and tuberous sclerosis complex (TSC) suggest that the BHD and TSC proteins may function within a common pathway. The TSC proteins inhibit the activity of the mammalian target of rapamycin complex 1 (TORC1), and in Schizosaccharomyces pombe , Bhd and Tsc1/Tsc2 have opposing roles in the regulation of amino-acid homeostasis. We report here that in mammalian cells, downregulation of BHD reduces the phosphorylation of ribosomal protein S6, an indicator of TORC1 activity. To determine whether folliculin, the product of the BHD gene, regulates mammalian target of rapamycin activity in vivo , we generated a mouse with targeted inactivation of the Bhd gene. The mice developed spontaneous oncocytic cysts and tumors composed of cells that resemble the renal cell carcinomas in BHD patients. The cysts and tumors had low levels of phospho-S6. Taken together, these data indicate that folliculin regulates the activity of TORC1, and suggest a new paradigm in which both inappropriately high and inappropriately low levels of TORC1 activity can be associated with renal tumorigenesis.

Birt-Hogg-Dubé (BHD) syndrome is an inherited cancer susceptibility disease characterized by skin and kidney tumors, as well as cystic lung disease, which results from loss-of-function mutations in the BHD gene which encodes the protein product Folliculin. BHD is also inactivated in a significant fraction of patients with sporadic renal cancers and idiopathic cystic lung disease, and little is known about its mode of action. To investigate the molecular and cellular basis of Folliculin's tumor suppressor activity, we generated mutant Bhd mice and embryonic stem cell lines. Folliculin-deficient cells exhibited defects in cell-intrinsic apoptosis that correlated with reduced expression of the BH3-only protein Bim, which was similarly observed in all human and murine BHD-related tumors examined. We further demonstrate that Bim protein deficiency in Bhd-/- cells is not a consequence of elevated mTOR or ERK activity, but results instead from reduced Bim transcription associated with altered TGFβ-mediated chromatin modifications. In aggregate, this work identifies a specific tumor suppressive mechanism for Folliculin in regulating TGFβ dependent apoptosis, which has implications for the development of targeted therapies. Future efforts aim to define how Folliculin regulates TGFβ-mediated chromatin modifications and transcriptional output.

Anti-cancer therapies often result in a subset of surviving cancer cells that undergo therapy-induced senescence (TIS). Senescent cancer cells strongly modify the intratumoural microenvironment favoring immunosuppression and, thereby, tumour growth. An emerging strategy to optimise current therapies is to combine them with treatments that eliminate senescent cells. To this end, we undertook an unbiased proteomics approach to identify surface markers contributing to senescent cells immune evasion. Through this approach, we discovered that the immune checkpoint inhibitor PD-L2, but not PD-L1, is upregulated across multiple senescent human and murine cells. Importantly, blockade of PD-L2 strongly synergises with genotoxic chemotherapy, causing remission of solid tumours in mice. We show that PD-L2 inhibition prevents the persistence of chemotherapy-induced senescent cells, which exert cell-extrinsic immunomodulatory actions. In particular, upon chemotherapy, tumours deficient in PD-L2 fail to produce cytokines of the CXCL family, do not recruit myeloid-derived suppressor cells (MDSCs) and are eliminated in a CD8 T cell-dependent manner. We conclude that blockade of PD-L2 improves chemotherapy efficacy by reducing the intratumoural burden of senescent cells and their associated recruitment of immunosuppressive cells. These findings provide a novel strategy to exploit vulnerabilities arising in tumour cells as a result of therapy-induced damage and cellular senescence.