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It has been recognized for decades that ERBB signaling is important in prostate cancer, but targeting ERBB receptors as a therapeutic strategy for prostate cancer has been ineffective clinically. However, we show here that membranous HER3 protein is commonly highly expressed in lethal prostate cancer, associating with reduced time to castration resistance (CR) and survival. Multiplex immunofluorescence indicated that the HER3 ligand NRG1 is detectable primarily in tumor-infiltrating myelomonocytic cells in human prostate cancer; this observation was confirmed using single-cell RNA sequencing of human prostate cancer biopsies and murine transgenic prostate cancer models. In castration-resistant prostate cancer (CRPC) patient-derived xenograft organoids with high HER3 expression as well as mouse prostate cancer organoids, recombinant NRG1 enhanced proliferation and survival. Supernatant from murine bone marrow–derived macrophages and myeloid-derived suppressor cells promoted murine prostate cancer organoid growth in vitro, which could be reversed by a neutralizing anti-NRG1 antibody and ERBB inhibition. Targeting HER3, especially with the HER3-directed antibody–drug conjugate U3-1402, exhibited antitumor activity against HER3-expressing prostate cancer. Overall, these data indicate that HER3 is commonly overexpressed in lethal prostate cancer and can be activated by NRG1 secreted by myelomonocytic cells in the tumor microenvironment, supporting HER3-targeted therapeutic strategies for treating HER3-expressing advanced CRPC. Significance: HER3 is an actionable target in prostate cancer, especially with anti-HER3 immunoconjugates, and targeting HER3 warrants clinical evaluation in prospective trials.

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The microbiota comprises the microorganisms that live in close contact with the host, with mutual benefit for both counterparts. The contribution of the gut microbiota to the emergence of castration-resistant prostate cancer (CRPC) has not yet been addressed. We found that androgen deprivation in mice and humans promotes the expansion of defined commensal microbiota that contributes to the onset of castration resistance in mice. Specifically, the intestinal microbial community in mice and patients with CRPC was enriched for species capable of converting androgen precursors into active androgens. Ablation of the gut microbiota by antibiotic therapy delayed the emergence of castration resistance even in immunodeficient mice. Fecal microbiota transplantation (FMT) from CRPC mice and patients rendered mice harboring prostate cancer resistant to castration. In contrast, tumor growth was controlled by FMT from hormone-sensitive prostate cancer patients and Prevotella stercorea administration. These results reveal that the commensal gut microbiota contributes to endocrine resistance in CRPC by providing an alternative source of androgens.

Endocrine resistance (EnR) in advanced prostate cancer is fatal. EnR can be mediated by androgen receptor (AR) splice variants, with AR splice variant 7 (AR-V7) arguably the most clinically important variant. In this study, we determined proteins key to generating AR-V7, validated our findings using clinical samples, and studied splicing regulatory mechanisms in prostate cancer models. Triangulation studies identified JMJD6 as a key regulator of AR-V7, as evidenced by its upregulation with in vitro EnR, its downregulation alongside AR-V7 by bromodomain inhibition, and its identification as a top hit of a targeted siRNA screen of spliceosome-related genes. JMJD6 protein levels increased (P < 0.001) with castration resistance and were associated with higher AR-V7 levels and shorter survival (P = 0.048). JMJD6 knockdown reduced prostate cancer cell growth, AR-V7 levels, and recruitment of U2AF65 to AR pre-mRNA. Mutagenesis studies suggested that JMJD6 activity is key to the generation of AR-V7, with the catalytic machinery residing within a druggable pocket. Taken together, these data highlight the relationship between JMJD6 and AR-V7 in advanced prostate cancer and support further evaluation of JMJD6 as a therapeutic target in this disease. Significance: This study identifies JMJD6 as being critical for the generation of AR-V7 in prostate cancer, where it may serve as a tractable target for therapeutic intervention.

Driver genes with a mutually exclusive mutation pattern across tumor genomes are thought to have overlapping roles in tumorigenesis. In contrast, we show here that mutually exclusive prostate cancer driver alterations involving the ERG transcription factor and the ubiquitin ligase adaptor SPOP are synthetic sick. At the molecular level, the incompatible cancer pathways are driven by opposing functions in SPOP. ERG upregulates wild type SPOP to dampen androgen receptor (AR) signaling and sustain ERG activity through degradation of the bromodomain histone reader ZMYND11. Conversely, SPOP-mutant tumors stabilize ZMYND11 to repress ERG-function and enable oncogenic androgen receptor signaling. This dichotomy regulates the response to therapeutic interventions in the AR pathway. While mutant SPOP renders tumor cells susceptible to androgen deprivation therapies, ERG promotes sensitivity to high-dose androgen therapy and pharmacological inhibition of wild type SPOP. More generally, these results define a distinct class of antagonistic cancer drivers and a blueprint toward their therapeutic exploitation., Nature Communications, 12, ISSN:2041-1723

Background Cell entry of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) depends on binding of the viral spike (S) proteins to angiotensin-converting enzyme 2 and on S protein priming by TMPRSS2. Inhibition of TMPRSS2 may work to block or decrease the severity of SARS-CoV-2 infections. Intriguingly, TMPRSS2 is an androgen-regulated gene that is up-regulated in prostate cancer where it supports tumor progression and is involved in a frequent genetic translocation with the ERG gene. First- or second-generation androgen-deprivation therapies (ADTs) decrease the levels of TMPRSS2. Here we put forward the hypothesis that ADTs may protect patients affected by prostate cancer from SARS-CoV-2 infections. Materials and methods We extracted data regarding 9280 patients (4532 males) with laboratory-confirmed SARS-CoV-2 infection from 68 hospitals in Veneto, one of the Italian regions that was most affected by the coronavirus disease 2019 (COVID-19) pandemic. The parameters used for each COVID-19-positive patient were sex, hospitalization, admission to intensive care unit, death, tumor diagnosis, prostate cancer diagnosis, and ADT. Results There were evaluable 9280 SARS-CoV-2-positive patients in Veneto on 1 April 2020. Overall, males developed more severe complications, were more frequently hospitalized, and had a worse clinical outcome than females. Considering only the Veneto male population (2.4 million men), 0.2% and 0.3% of non-cancer and cancer patients, respectively, tested positive for SARS-CoV-2. Comparing the total number of SARS-CoV-2-positive cases, prostate cancer patients receiving ADT had a significantly lower risk of SARS-CoV-2 infection compared with patients who did not receive ADT (OR 4.05; 95% CI 1.55–10.59). A greater difference was found comparing prostate cancer patients receiving ADT with patients with any other type of cancer (OR 4.86; 95% CI 1.88–12.56). Conclusion Our data suggest that cancer patients have an increased risk of SARS-CoV-2 infections compared with non-cancer patients. However, prostate cancer patients receiving ADT appear to be partially protected from SARS-CoV-2 infections.

Oncogene addiction postulates that the survival and growth of certain tumor cells is dependent upon the activity of one oncogene, despite their multiple genetic and epigenetic abnormalities. This phenomenon provides a foundation for molecular targeted therapy and a rationale for oncogene-based stratification. We have previously reported that the Promyelocytic Leukemia protein (PML) is upregulated in triple negative breast cancer (TNBC) and it regulates cancer-initiating cell function, thus suggesting that this protein can be therapeutically targeted in combination with PML-based stratification. However, the effects of PML perturbation on the bulk of tumor cells remained poorly understood. Here we demonstrate that TNBC cells are addicted to the expression of this nuclear protein. PML inhibition led to a remarkable growth arrest combined with features of senescence in vitro and in vivo. Mechanistically, the growth arrest and senescence were associated to a decrease in MYC and PIM1 kinase levels, with the subsequent accumulation of CDKN1B (p27), a trigger of senescence. In line with this notion, we found that PML is associated to the promoter regions of MYC and PIM1, consistent with their direct correlation in breast cancer specimens. Altogether, our results provide a feasible explanation for the functional similarities of MYC, PIM1, and PML in TNBC and encourage further study of PML targeting strategies for the treatment of this breast cancer subtype. Aologies to those whose related publications were not cited due to space limitations. LA, AS, MPu, AA-A, and LV-J were supported by the Basque Government of education. IH was supported by the Program "Juan de la Cierva" from MINECO. FC acknowledges the Proteomics Unit at VHIO is a member ProteoRed, PRB3 (Grant IPT17/0019-ISCIII-SGEFI/ERDF. RB acknowledges projects BFU2017-84653-P, Consolider BFU2014-57703-REDC, and SAF2017-90900-REDT (MINECO/FEDER, EU). The work of VT is founded by Fundacion Vasca de Innovacion e Investigacion Sanitarias, BIOEF (BIO15/CA/052), the AECC J.P. Bizkaia, the Basque Department of Health (2016111109) and the MINECO (RTI2018-097267-B-I00 (MCIU/AEI/FEDER, UE)). AA was supported by ERC consolidator (683136) and Swiss Cancer League (KFS4267-08-2017) grant, Dr. Josef Steiner Foundation, Swiss CardOnco-Grant of Alfred and Annemarie von Sick grant, Helmut Horten Foundation, SNSF (310030_176045) and PCUK (RIA15-ST2-018). NM-M was supported by the Spanish Association Against Cancer (AECC), AECC JP Vizcaya and CIBERONC. The work of A. Carracedo is supported by the Basque Department of Industry, Tourism and Trade (Elkartek) and the department of education (IKERTALDE IT1106-16), the BBVA foundation, the MINECO (SAF2016-79381R (FEDER/EU); Severo Ochoa Excellence Accreditation SEV2016-0644; Excellence Networks SAF2016-81975-REDT), European Training Networks Project (H2020-MSCA-ITN-308 2016 721532), the AECC (IDEAS175CARR, GCTRA18006CARR), La Caixa Foundation (HR17-00094), FERO foundation, the AstraZeneca Oncology prize and the European Research Council (Starting Grant 336343, PoC 754627). CIBERONC was co-funded with FEDER funds and funded by ISCIII.

Prostate cancer is a major cause of cancer morbidity and mortality. Intra-prostatic inflammation is a risk factor for prostate carcinogenesis, with diet, chemical injury and an altered microbiome being causally implicated. Intra-prostatic inflammatory cell recruitment and expansion can ultimately promote DNA double-strand breaks and androgen receptor activation in prostate epithelial cells. The activation of the senescence-associated secretory phenotype fuels further 'inflammatory storms', with free radicals leading to further DNA damage. This drives the overexpression of DNA repair and tumour suppressor genes, rendering these genes susceptible to mutagenic insults, with carcinogenesis accelerated by germline DNA repair gene defects. We provide updates on recent advances in elucidating prostate carcinogenesis and explore novel therapeutic and prevention strategies harnessing these discoveries.

The mechanisms by which prostate cancer shifts from an indolent castration-sensitive phenotype to lethal castration-resistant prostate cancer (CRPC) are poorly understood. Identification of clinically relevant genetic alterations leading to CRPC may reveal potential vulnerabilities for cancer therapy. Here we find that CUB domain-containing protein 1 (CDCP1), a transmembrane protein that acts as a substrate for SRC family kinases (SFKs), is overexpressed in a subset of CRPC. Notably, CDCP1 cooperates with the loss of the tumor suppressor gene PTEN to promote the emergence of metastatic prostate cancer. Mechanistically, we find that androgens suppress CDCP1 expression and that androgen deprivation in combination with loss of PTEN promotes the upregulation of CDCP1 and the subsequent activation of the SRC/MAPK pathway. Moreover, we demonstrate that anti-CDCP1 immunoliposomes (anti–CDCP1 ILs) loaded with chemotherapy suppress prostate cancer growth when administered in combination with enzalutamide. Thus, our study identifies CDCP1 as a powerful driver of prostate cancer progression and uncovers different potential therapeutic strategies for the treatment of metastatic prostate tumors. ISSN:0021-9738 ISSN:1558-8238

Activation of NOTCH signalling is associated with advanced prostate cancer and treatment resistance in prostate cancer patients. However, the mechanism that drives NOTCH activation in prostate cancer remains still elusive. Moreover, preclinical evidence of the therapeutic efficacy of NOTCH inhibitors in prostate cancer is lacking. Here, we provide evidence that PTEN loss in prostate tumours upregulates the expression of ADAM17, thereby activating NOTCH signalling. Using prostate conditional inactivation of both Pten and Notch1 along with preclinical trials carried out in Pten-null prostate conditional mouse models, we demonstrate that Pten-deficient prostate tumours are addicted to the NOTCH signalling. Importantly, we find that pharmacological inhibition of γ-secretase promotes growth arrest in both Pten-null and Pten/Trp53-null prostate tumours by triggering cellular senescence. Altogether, our findings describe a novel pro-tumorigenic network that links PTEN loss to ADAM17 and NOTCH signalling, thus providing the rational for the use of γ-secretase inhibitors in advanced prostate cancer patients., Notch signalling is involved in prostate cancer progression and therapeutic resistance. Here, the authors show that loss of PTEN in prostate cancer models results in increased Notch1 cleavage and activation through CUX1-mediated transactivation of ADAM17.

International audience; Cellular senescence is a cell state implicated in various physiological processes and a wide spectrum of age-related diseases. Recently, interest in therapeutically targeting senescence to improve healthy aging and age-related disease, otherwise known as senotherapy, has been growing rapidly. Thus, the accurate detection of senescent cells, especially in vivo, is essential. Here, we present a consensus from the International Cell Senescence Association (ICSA), defining and discussing key cellular and molecular features of senescence and offering recommendations on how to use them as biomarkers. We also present a resource tool to facilitate the identification of genes linked with senescence, SeneQuest (available at http://Senequest.net). Lastly, we propose an algorithm to accurately assess and quantify senescence, both in cultured cells and in vivo.

Cellular senescence is a permanent state of cell cycle arrest that occurs in proliferating cells subjected to different stresses. Senescence is, therefore, a cellular defense mechanism that prevents the cells to acquire an unnecessary damage. The senescent state is accompanied by a failure to re-enter the cell cycle in response to mitogenic stimuli, an enhanced secretory phenotype and resistance to cell death. Senescence takes place in several tissues during different physiological and pathological processes such as tissue remodeling, injury, cancer, and aging. Although senescence is one of the causative processes of aging and it is responsible of aging-related disorders, senescent cells can also play a positive role. In embryogenesis and tissue remodeling, senescent cells are required for the proper development of the embryo and tissue repair. In cancer, senescence works as a potent barrier to prevent tumorigenesis. Therefore, the identification and characterization of key features of senescence, the induction of senescence in cancer cells, or the elimination of senescent cells by pharmacological interventions in aging tissues is gaining consideration in several fields of research. Here, we describe the known key features of senescence, the cell-autonomous, and noncell-autonomous regulators of senescence, and we attempt to discuss the functional role of this fundamental process in different contexts in light of the development of novel therapeutic targets.

Summary Tumor-associated macrophages (TAMs) represent a major component of the tumor microenvironment supporting tumorigenesis. TAMs re-education has been proposed as a strategy to promote tumor inhibition. However, whether this approach may work in prostate cancer is unknown. Here we find that Pten-null prostate tumors are strongly infiltrated by TAMs expressing C-X-C chemokine receptor type 2 (CXCR2), and activation of this receptor through CXCL2 polarizes macrophages toward an anti-inflammatory phenotype. Notably, pharmacological blockade of CXCR2 receptor by a selective antagonist promoted the re-education of TAMs toward a pro-inflammatory phenotype. Strikingly, CXCR2 knockout monocytes infused in Ptenpc−/−; Trp53pc−/− mice differentiated in tumor necrosis factor alpha (TNF-α)-releasing pro-inflammatory macrophages, leading to senescence and tumor inhibition. Mechanistically, PTEN-deficient tumor cells are vulnerable to TNF-α-induced senescence, because of an increase of TNFR1. Our results identify TAMs as targets in prostate cancer and describe a therapeutic strategy based on CXCR2 blockade to harness anti-tumorigenic potential of macrophages against this disease., Graphical Abstract, Highlights • CXCR2 blockade drives re-education of tumor-associated macrophages (TAMs) • Infusion of CXCR2-KO monocytes in tumor-bearing mice blocks tumor progression • PTEN deletion sensitizes tumor cells to TNF-α-induced senescence and growth arrest, Di Mitri et al. show that CXCR2 blockade in prostate cancer triggers TAMs re-education, leading to tumor inhibition. CXCR2-KO monocytes infused in Ptenpc−/−; Trp53pc−/− tumor-bearing mice differentiate into TNFα-releasing pro-inflammatory macrophages that induce senescence in tumor cells. PTEN-null tumors display higher sensitivity to TNF-α-induced senescence because of TNFR1 upregulation.

Metastases account for most cancer-related deaths, yet the mechanisms underlying metastatic spread remain poorly understood. Recent evidence demonstrates that senescent cells, while initially restricting tumorigenesis, can induce tumor progression. Here, we identify the metalloproteinase inhibitor TIMP1 as a molecular switch that determines the effects of senescence in prostate cancer. Senescence driven either by PTEN deficiency or chemotherapy limits the progression of prostate cancer in mice. TIMP1 deletion allows senescence to promote metastasis, and elimination of senescent cells with a senolytic BCL-2 inhibitor impairs metastasis. Mechanistically, TIMP1 loss reprograms the senescence-associated secretory phenotype (SASP) of senescent tumor cells through activation of matrix metalloproteinases (MMPs). Loss of PTEN and TIMP1 in prostate cancer is frequent and correlates with resistance to docetaxel and worst clinical outcomes in patients treated in an adjuvant setting. Altogether, these findings provide insights into the dual roles of tumor-associated senescence and can potentially impact the treatment of prostate cancer.

Recent studies have raised fundamental questions about the possibility that senescence induced either by oncogene activation or chemotherapy, while initially restricting tumorigenesis, may promote cancer metastases at a late stage. This coexisting dichotomy remains unclear due to the lack of evidence on the mechanism by which senescent tumor cells initiate metastases, a fatal and therapeutically challenging hallmark of cancer. Here, we put forward the hypothesis that the genetic make-up of the tumors accounts for the distinct outcomes of senescence in cancer. Using different genetically engineered mouse models we demonstrate that inactivation of Timp1 is capable to switch senescence driven by the loss of PTEN and chemotherapy from a tumor-suppressive into a tumor-promoting response that drives metastases. Of note, depletion of senescent tumor cells by the senolytic compound ABT263 or p53 genetic inactivation significantly impeded metastases formation in Ptenpc-/-; Timp1-/- mice, indicating the involvement of senescence in the metastatic process. Moreover, enhancement of senescence by Docetaxel therapy decreased the proliferation of prostate tumors in Ptenpc-/- mice, whereas it accelerated metastases formation in Ptenpc-/-; Timp1-/- mice. Mechanistically, TIMP1-loss in PTEN-deficient cells reprogrammed the senescent-secretome significantly changing the levels of GDF15, FGF and IGFBP thereby promoting cellular invasion, migration and the up-regulation of a metastases-associated gene signature. In prostate cancer patients, we found that TIMP1 is commonly lost in combination with PTEN in advanced and metastatic prostate tumors and that TIMP1 inactivation is associated with TIMP1 promoter methylation. Altogether, these findings highlight the crucial role of TIMP1 as the gatekeeper that limits the pro-metastatic function of senescent tumor cells, implying that senescence inducing therapies should be administered with caution in patients affected by cancers with TIMP1 inactivation. Citation Format: Ilaria Guccini, Ajinkya Revandkar, Mariantonietta D'Ambrosio, Manuel Colucci, Emiliano Pasquini, Simone Mosole, Martina Troiani, Andrea Alimonti. Senescence reprogramming in primary tumors initiates prostate cancer metastases [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr LB-005.

Nature 547, 109–113 (2017); doi:10.1038/nature22964 In this Letter, there are errors in Extended Data Figs 5, 8 and 9, and the affiliation of an author. The affiliations for author Violeta Serra should include number 2 (CIBERONC, Instituto de Salud Carlos III, C/ Monforte de Lemos 3-5, Pabellon 11, Planta 0, 28029 Madrid, Spain).

Patients with prostate cancer frequently show resistance to androgen-deprivation therapy, a condition known as castration-resistant prostate cancer (CRPC). Acquiring a better understanding of the mechanisms that control the development of CRPC remains an unmet clinical need. The well-established dependency of cancer cells on the tumour microenvironment indicates that the microenvironment might control the emergence of CRPC. Here we identify IL-23 produced by myeloid-derived suppressor cells (MDSCs) as a driver of CRPC in mice and patients with CRPC. Mechanistically, IL-23 secreted by MDSCs can activate the androgen receptor pathway in prostate tumour cells, promoting cell survival and proliferation in androgen-deprived conditions. Intra-tumour MDSC infiltration and IL-23 concentration are increased in blood and tumour samples from patients with CRPC. Antibody-mediated inactivation of IL-23 restored sensitivity to androgen-deprivation therapy in mice. Taken together, these results reveal that MDSCs promote CRPC by acting in a non-cell autonomous manner. Treatments that block IL-23 can oppose MDSC-mediated resistance to castration in prostate cancer and synergize with standard therapies.

SummaryUnderstanding the molecular pathways that contribute to the aggressive behavior of HER2-positive breast cancers may aid in the development of novel therapeutic interventions. Here, we show that CDCP1 and HER2 are frequently co-overexpressed in metastatic breast tumors and associated with poor patient prognosis. HER2 and CDCP1 co-overexpression leads to increased transformation ability, cell migration, and tumor formation in vivo, and enhanced HER2 activation and downstream signaling in different breast cancer cell lines. Mechanistically, we demonstrate that CDCP1 binds to HER2 through its intracellular domain, thereby increasing HER2 interaction with the non-receptor tyrosine kinase c-SRC (SRC), leading to trastuzumab resistance. Taken together, our findings establish that CDCP1 is a modulator of HER2 signaling and a biomarker for the stratification of breast cancer patients with poor prognosis. Our results also provide a rationale for therapeutic targeting of CDCP1 in HER2-positive breast cancer patients.

Users may view, print, copy, and download text and data-mine the content in such documents, for the purposes of academic research, subject always to the full Conditions of use: http://www.nature.com/authors/editorial_policies/license.html#terms Activation of the PTEN-PI3K-mTORC1 pathway consolidates metabolic programs that sustain cancer cell growth and proliferation,. Here we show that mTORC1 regulates polyamine dynamics, a metabolic route that is essential for oncogenicity. Through the use of integrative metabolomics in a mouse model and human biopsies of prostate cancer, we identified alterations in tumours impacting on the production of decarboxylated S-adenosylmethionine (dcSAM) and polyamine synthesis. Mechanistically, this metabolic rewiring stems from mTORC1-dependent regulation of S-adenosylmethionine decarboxylase 1 (AMD1) stability. This novel molecular regulation was validated in murine and human cancer specimens. AMD1 was upregulated in prostate cancer specimens with activated mTORC1. Conversely, samples from a clinical trial with the mTORC1 inhibitor everolimus exhibited a predominant decrease in AMD1 immunoreactivity that was associated to a decrease in proliferation, in line with the requirement of dcSAM production for oncogenicity. These findings provide fundamental information about the complex regulatory landscape controlled by mTORC1 to integrate and translate growth signals into an oncogenic metabolic program.

Objective Clinical expression of SS shows considerable interpatient heterogeneity. Thus, the aim of this study was to assess whether individual salivary proteomic profiles provide a framework for identification of disease-phenotype-driven biomarker signatures. Methods Using a 187-plex capture antibody-based assay, proteomic biomarker profiles from unstimulated whole saliva were generated from a SS-cohort representing six clinically distinct disease phenotypes. Discriminant function analyses identified the most powerful biomarker signatures for correct recapitulation of each patient's status with respect to hyposalivation and histopathological features of salivary gland inflammation. In addition, gene ontology-based network analyses allowed systematic interpretation of the molecular patterns underlying these specific disease features. Results Presentation of hyposalivation was associated with significant alteration in 22 out of 119 reliably detectable biomarkers. Thereof, a 4-plex signature allowed accurate prediction of salivary gland function for >80% of the cases. With respect to histopathological features, the most distinct profiles were identified in conjunction with ectopic germinal centres. Selected from the 13 analytes relevant here, pregnancy-associated plasma protein A, thrombospondin 1 and peptide YY would recapitulate the presence or absence of tertiary lymphoid organization for 93.8% of the patients. Whereas functional annotation of alterations associated with hyposalivation identified the IL1 system as a dominant pro-inflammatory component, changes observed in context with ectopic lymphoid organization revealed specific shifts in chemotactic profiles and altered regulation of apoptotic processes. Conclusion Multivariate analyses of a patient's salivary proteome could reliably recapitulate specific aspects of SS disease. Accessible and repetitively collectable, such biomarker signatures harbour great potential for patient subclassification and subsequent follow-up.

Cellular senescence is a permanent growth arrest that is broadly recognized to act as a barrier against tumorigenesis. Senescence is predominant in premalignant tumors, and senescence escape is thought to be required for tumor progression. Importantly, evidences indicate that cell-autonomous mechanisms, such as genetic alterations or therapeutic interventions targeting specific genetic pathways, can affect the senescence response in cancer. Nevertheless, new findings have emerged in the last few years that indicate a fundamental role for the tumor microenvironment in the regulation of cellular senescence. Indeed, cytokines belonging to the senescent secretome, as well as tumor-infiltrating immune subsets, have been described to modulate the senescence response in tumors. Such evidence demonstrates that senescence initiation also relies on non-cell-autonomous mechanisms, which are discussed in the present review.

Prostate cancer cells are surrounded by a complex tumor microenvironment that controls prostate cancer progression and treatment resistance. We are interested in understanding the liaison between tumor-infiltrating myeloid cells and prostate cancer cells to identify new molecular mechanisms that regulate cancer progression and the emergence of castration-resistant prostate cancer (CRPC). We have previously demonstrated that myeloid-derived suppressor cells (MDSCs) trigger senescence evasion and immunosuppression in primary prostate cancers, eventually promoting tumor progression. These studies have provided the rationale to develop in the clinic novel immune therapies targeting MDSCs for the therapy of metastatic prostate cancer patients. I will present recent results on additional tumor-promoting functions played by MDSCs and tumor-associated macrophages (TAMs) in prostate cancer, and I will discuss new therapeutic strategies that combine the use of immunotherapy with androgen deprivation therapy for the treatment of CRPC Citation Format: Andrea Alimonti. Targeting tumor-infiltrating myeloid cells for prostate cancer therapy [abstract]. In: Proceedings of the AACR Special Conference: Prostate Cancer: Advances in Basic, Translational, and Clinical Research; 2017 Dec 2-5; Orlando, Florida. Philadelphia (PA): AACR; Cancer Res 2018;78(16 Suppl):Abstract nr IA22.

In the HTML version of this article initially published, the name of author Diletta Di Mitri was miscoded in the XML such that Di was included as part of the given name instead of the family name. The error has been corrected in the HTML version of the article.

Senescence induction in cancer works as a potent weapon to eradicate tumorigenesis. Therapies that enhance senescence not only promote a stable cell growth arrest but also work as a strong stimulus for the activation of the tumor immune response. However, cancer cells bypass senescence by either acquiring new genetic alterations or by disrupting the tumor immune response. Here, I will discuss the identification of oncogenic pathways that bypass Pten-loss-induced cellular senescence, thereby promoting prostate cancer progression and metastasis. Next, I will present evidence demonstrating that both tumor-infiltrating myeloid-derived suppressor cells (MDSCs) and tumor-associated macrophages (TAMs) control senescence induction in chemotherapy-treated prostate cancers and that immunotherapies that interfere with either MDSCs' recruitment or the polarization of TAMs promote senescence in advanced PTEN-deficient prostate cancer. Citation Format: Andrea Alimonti. Dual targeting of senescence and tumor immunity for cancer therapy [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr SY26-03.

The mammalian target of rapamycin (mTOR) represents a critical signaling crossroad where pathways commonly disrupted in cancer converge. We report here that Rheb GTPase, the upstream activator of the mTOR complex 1 (mTORC1) is amplified in human prostate cancers. We demonstrate that Rheb overexpression promotes hyperplasia and a low-grade neoplastic phenotype in the mouse prostate while eliciting a concomitant senescence response and a negative feedback loop limiting Akt activation. Importantly, we show that Pten haploinsufficiency cooperates with Rheb overexpression to markedly promote prostate tumorigenesis. We conclude that Rheb acts as a proto-oncogene in the appropriate genetic milieu and signaling context.

The PTEN tumor-suppressor is frequently affected in cancer, and inherited PTEN mutation causes cancer-susceptibility conditions such as Cowden Syndrome. PTEN acts as a plasma-membrane lipid-phosphatase antagonizing the PI-3-Kinase/AKT pathway. However, PTEN is also found in cell nuclei, but mechanism, function and relevance of nuclear localization have remained unclear. Here we show that nuclear PTEN is essential for tumor-suppression and that import is mediated by its mono-ubiquitination. We show that a lysine-mutant of PTEN, which retains catalytic activity yet causes Cowden Syndrome, fails to accumulate in nuclei of patient tissue due to an import defect. We identify this and another lysine-residue as major mono-ubiquitination sites essential for PTEN import. Poly-ubiquitination in contrast, leads to PTEN degradation in the cytoplasm, while nuclear PTEN is stable, antagonizes AKT and causes apoptosis. We thus identify the first cancer-associated mutations of PTEN that target post-translational modification and demonstrate how a discrete molecular mechanism dictates tumor-progression by differentiating between degradation and protection of PTEN.

Tumor-infiltrating myeloid-derived suppressor cells (MDSC) are a heterogeneous and immunosuppressive cell subset that blocks the proliferation and the activity of both T and natural killer (NK) cells and promotes tumor vasculogenesis and progression. Recent evidences demonstrate that the recruitment of MDSCs in tumors also blocks senescence induced by chemotherapy promoting chemoresistance. Hence, the need of novel therapeutic approaches that can efficiently target MDSC recruitment and function in cancer. Among them, novel combinatorial treatments of chemotherapy and immunotherapy or treatments that induce depletion of MDSCs in peripheral sites should be taken in consideration. Clin Cancer Res; 21(14); 3108–12. ©2015 AACR.

Cellular senescence is a stable cell cycle arrest that occurs in diploid cells during aging. However, diploid cells can also experience an accelerated senescence response, termed pre-mature senescence, driven by DNA-damage, oncogene over-expression or loss of tumour suppressor genes. Recent evidences demonstrate that cellular senescence occurs also in tumours, where it opposes tumour initiation and progression. Senescence cells secrete a variety of cytokines and secreted factors, known as the senescence secretory phenotype (SASP), that regulate both the senescence entry and maintenance and can propagate senescence to adjacent cells, acting in a cell non-autonomous manner. In addition, SASP can also promote the recruitment and activation of immune cells that in turn mediate the clearance of senescent cancer cells.

Senescent cells promote tumor clearance by evoking an antitumor immune response. However in Pten-null prostate tumors treated with chemotherapy, the antitumor immune response is blocked by activati...

Loss of the promyelocytic leukaemia (PML) tumour suppressor has been observed in several human cancers. The tumour-suppressive function of PML has been attributed to its ability to induce growth arrest, cellular senescence and apoptosis. Here we identify PML as a critical inhibitor of neoangiogenesis (the formation of new blood vessels) in vivo, in both ischaemic and neoplastic conditions, through the control of protein translation. We demonstrate that in hypoxic conditions PML acts as a negative regulator of the synthesis rate of hypoxia-inducible factor 1α (HIF-1α) by repressing mammalian target of rapamycin (mTOR). PML physically interacts with mTOR and negatively regulates its association with the small GTPase Rheb by favouring mTOR nuclear accumulation. Notably, Pml-/- cells and tumours display higher sensitivity both in vitro and in vivo to growth inhibition by rapamycin, and lack of PML inversely correlates with phosphorylation of ribosomal protein S6 and tumour angiogenesis in mouse and human tumours. Thus, our findings identify PML as a novel suppressor of mTOR and neoangiogenesis. The tumour suppressor PML ('promyelocytic leukaemia') is shown to be an inhibitor of blood vessel formation in tumours and in tissue recovering from ischaemia. Loss of PML is associated with a range of human cancers. Its role in angiogenesis control marks it as a drug target in cancers, where upregulation is the aim, and in encouraging blood vessel formation following ischaemic heart attack or stroke, by downregulation. The tumour suppressor gene PML is shown to normally restrain angiogenesis, both in tumours and under ischaemic conditions. This involves a new pathway in which during hypoxia, PML regulates mTOR and the transcription factor HIF-1α

The aim was to investigate the activity of docetaxel in advanced gastric cancer either as single agent or in combination with other drugs. A systematic review was carried out using the databases of Medline, Embase and CancerLit. Results from ASCO and ESMO meetings during 2002 were also included. Eight phase II trials focused on docetaxel as a single agent. Considering collectively the 262 evaluable patients enrolled in these studies, the mean response rate (RR) was 19% (CI 95% 14-24%). Docetaxel was well tolerated with a dose-limiting myelosuppression (grade 3-4 neutropenia in 36-95% of cases). Adding fluorouracil, an RR ranging from 22% to 86% was registered, due to differences in populations studied (young vs elderly) and modalities of drug administration (continuous vs. bolus infusion). RRs for docetaxel-cisplatin combination were 56%, 37% and 36% in three phase II trials and 35% in a phase III trial. The addition of both cisplatin and fluorouracil to docetaxel did not increase toxicity. Randomized trials comparing docetaxel-cisplatin-fluorouracil with ciplatin-fluorouoracil or epirubicin-cisplatin-fluorouracil, the most commonly used regimens, are ongoing. The future results of the above phase III studies could indicate docetaxel as a key drug to improve treatment of patients with advanced gastric cancer.

Enhancement of cellular senescence in tumours triggers a stable cell growth arrest and activation of an antitumour immune response that can be exploited for cancer therapy. Currently, there are only a limited number of targeted therapies that act by increasing senescence in cancers, but the majority of them are not selective and also target healthy cells. Here we developed a chemogenomic screening to identify compounds that enhance senescence in PTEN-deficient cells without affecting normal cells. By using this approach, we identified casein kinase 2 (CK2) as a pro-senescent target. Mechanistically, we show that Pten loss increases CK2 levels by activating STAT3. CK2 upregulation in Pten null tumours affects the stability of Pml, an essential regulator of senescence. However, CK2 inhibition stabilizes Pml levels enhancing senescence in Pten null tumours. Taken together, our screening strategy has identified a novel STAT3-CK2-PML network that can be targeted for pro-senescence therapy for cancer.

Marine-derived compounds have been explored and considered as possible antitumor agents. In this study, we analyzed extracts of the sponge Cribrochalina vasculum for their ability to inhibit tumor cell proliferation. Screening identified two acetylenic compounds of similar structure that showed strong tumor-specific toxicity in non–small cell lung carcinoma (NSCLC) cells and small-cell lung carcinoma cells, and less prominent toxicity in ovarian carcinoma, while having no effect on normal cells. These acetylenic compounds were found to cause a time-dependent increase in activation of apoptotic signaling involving cleavage of caspase-9, caspase-3, and PARP, as well as apoptotic cell morphology in NSCLC cells, but not in normal fibroblasts. Further analysis demonstrated that these compounds caused conformational change in Bak and Bax, and resulted in loss of mitochondrial potential and cytochrome c release in NSCLC cells. Moreover, a decreased phosphorylation of the growth factor signaling kinases Akt, mTOR, and ERK was evident and an increased phosphorylation of JNK was observed. Thus, these acetylenic compounds hold potential as novel therapeutic agents that should be further explored for NSCLC and other tumor malignancies. Mol Cancer Ther; 13(12); 2941–54. ©2014 AACR.

11116 Background: Pten loss-induced cellular senescence (PICS) is characterized by the absence of hyper-replication, as well as lack of DNA damage response. Therapeutic enhancement of cellular sene...

Summary: Prosenescence therapy has recently emerged as a novel therapeutic approach for treating cancer. However, this concept is challenged by conflicting evidence showing that the senescence-associated secretory phenotype (SASP) of senescent tumor cells can have pro- as well as antitumorigenic effects. Herein, we report that, in Pten-null senescent tumors, activation of the Jak2/Stat3 pathway establishes an immunosuppressive tumor microenvironment that contributes to tumor growth and chemoresistance. Activation of the Jak2/Stat3 pathway in Pten-null tumors is sustained by the downregulation of the protein tyrosine phosphatase PTPN11/SHP2, providing evidence for the existence of a novel PTEN/SHP2 axis. Importantly, treatment with docetaxel in combination with a JAK2 inhibitor reprograms the SASP and improves the efficacy of docetaxel-induced senescence by triggering a strong antitumor immune response in Pten-null tumors. Altogether, these data demonstrate that immune surveillance of senescent tumor cells can be suppressed in specific genetic backgrounds but also evoked by pharmacological treatments. : Cytokines released by senescent cells can have pro- as well as antitumorigenic effects. Here, Toso et al. show that cytokines released by Pten-null senescent prostate tumors drive an immunosuppressive tumor microenvironment. Pharmacological inhibition of the Jak2/Stat3 pathway in Pten-deficient prostate tumors reprograms the senescence-associated cytokine network, leading to an antitumor immune response that enhances chemotherapy efficacy. These data demonstrate that immune surveillance of senescent tumor cells can be suppressed in specific genetic backgrounds but is also evoked by pharmacological treatments.

Loss of the tumor suppressor gene PTEN opposes malignant transformation by triggering a cellular senescence response. This process is finely tuned by both cell-autonomous and non-cell-autonomous mechanisms that regulate the entry of tumor cells to senescence. I will discuss recent findings demonstrating that at the onset of senescence, PTEN null prostate tumors are infiltrated by a population of CD11b+Gr-1+ myeloid cells that protect a fraction of proliferating tumor cells from senescence, thus sustaining tumor growth. Mechanistically, I found that Gr-1+ cells antagonize senescence in a paracrine manner by interfering with the senescence-associated secretory phenotype (SASP) of the tumor through the secretion of interleukin-1 receptor antagonist. Therapeutically, I will present evidence that therapy-induced senescence and efficacy can be enhanced in PTEN null tumors by treatment that affect the recruitment of tumor-infiltrating CD11b+Gr-1+ myeloid cells or that reprogram the SASP. Taken together these data identify a novel non-cell-autonomous network, established by the innate immunity, that controls senescence evasion and chemoresistance in cancer. Targeting this network provides novel opportunities for cancer therapy. Citation Format: Andrea Alimonti. Non-cell autonomous regulation of senescence in cancer and cancer therapy. [abstract]. In: Proceedings of the AACR Special Conference: Function of Tumor Microenvironment in Cancer Progression; 2016 Jan 7–10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2016;76(15 Suppl):Abstract nr IA09.