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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.

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.

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 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.

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.

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.

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.

Abundant evidence points to a crucial physiological role for cellular senescence in combating tumorigenesis. Thus, the engagement of senescence may represent a key component for therapeutic intervention in the eradication of cancer. In this Opinion article, we focus on concepts that are relevant to a pro-senescence approach to therapy and we propose potential therapeutic strategies that aim to enhance the pro-senescence response in tumours.

Cancer susceptibility has been attributed to at least one heterozygous genetic alteration in a tumor suppressor gene (TSG)1. It has been hypothesized that subtle variations in TSG expression can promote cancer development2,3. However, this hypothesis has not yet been definitively supported in vivo. PTEN is a TSG frequently lost in human cancer and mutated in inherited cancer-predisposition syndromes4. Here, we analyze Pten hypermorphic mice (Ptenhy/+), expressing 80% normal levels of Pten. Ptenhy/+ mice develop a spectrum of tumors, with breast tumors occurring at the highest penetrance. All breast tumors analyzed here retained two intact copies of Pten and maintained Pten levels above heterozygosis. Notably, subtle downregulation of Pten altered the steady-state biology of the mammary tissues and the expression profiles of genes involved in cancer cell proliferation. We present an alterative working model for cancer development in which subtle reductions in the dose of TSGs predispose to tumorigenesis in a tissue-specific manner.

Pier Paolo Pandolfi and colleagues report that prostate-specific overexpression of ERG in transgenic mice results in no overt phenotype on its own but promotes progression of intraepithelial neoplasia to adenocarcinoma in a PTEN heterozygous background. They also find that human TMPRSS2-ERG–positive tumors are enriched for PTEN loss, suggesting that these two events cooperate in human prostate tumorigenesis. Chromosomal translocations involving the ERG locus are frequent events in human prostate cancer pathogenesis; however, the biological role of aberrant ERG expression is controversial1. Here we show that aberrant expression of ERG is a progression event in prostate tumorigenesis. We find that prostate cancer specimens containing the TMPRSS2-ERG rearrangement are significantly enriched for loss of the tumor suppressor PTEN. In concordance with these findings, transgenic overexpression of ERG in mouse prostate tissue promotes marked acceleration and progression of high-grade prostatic intraepithelial neoplasia (HGPIN) to prostatic adenocarcinoma in a Pten heterozygous background. In vitro overexpression of ERG promotes cell migration, a property necessary for tumorigenesis, without affecting proliferation. ADAMTS1 and CXCR4, two candidate genes strongly associated with cell migration, were upregulated in the presence of ERG overexpression. Thus, ERG has a distinct role in prostate cancer progression and cooperates with PTEN haploinsufficiency to promote progression of HGPIN to invasive adenocarcinoma.

One reported function of the tumor suppressor p19 Arf is to stabilize p53, providing a critical checkpoint in the response to oncogenic insults. Acute loss of Pten leads to an increase in the abundance of p19 Arf , p53, and p21 proteins as part of a fail-safe senescence response. Here, we report that loss of p19 Arf in prostate epithelium does not accelerate—but rather partially inhibits—the prostate cancer phenotype of Pten -deficient mice. Moreover, cellular senescence and a further decrease in the number of pre-neoplastic glands were observed in prostates of the Pten-p19 Arf double-mutant mice. In both prostate epithelium and primary mouse embryo fibroblasts (MEFs), the increase in p53 protein abundance found upon loss of Pten was unaffected by the simultaneous loss of p19 Arf . However, in contrast to that in the prostate epithelium, p19 Arf deficiency in MEFs lacking Pten abolished cell senescence and promoted hyperproliferation and transformation despite the unabated increase in p53 abundance. Consistent with the effect of p19 Arf loss in Pten-deficient mouse prostate, we found that in human prostate cancers, loss of PTEN was not associated with loss of p14 ARF (the human equivalent of mouse p19 Arf ). Collectively, these data reveal differential consequences of p19 Arf inactivation in prostate cancer and MEFs upon Pten loss that are independent of the p53 pathway.

Recently, we identified recurrent gene fusions involving the 5' untranslated region of the androgen-regulated gene TMPRSS2 and the ETS (E26 transformation-specific) family genes ERG, ETV1 or ETV4 in most prostate cancers. Whereas TMPRSS2-ERG fusions are predominant, fewer TMPRSS2-ETV1 cases have been identified than expected on the basis of the frequency of high (outlier) expression of ETV1 (refs 3-13). Here we explore the mechanism of ETV1 outlier expression in human prostate tumours and prostate cancer cell lines. We identified previously unknown 5' fusion partners in prostate tumours with ETV1 outlier expression, including untranslated regions from a prostate-specific androgen-induced gene (SLC45A3) and an endogenous retroviral element (HERV-K_22q11.23), a prostate-specific androgen-repressed gene (C15orf21), and a strongly expressed housekeeping gene (HNRPA2B1). To study aberrant activation of ETV1, we identified two prostate cancer cell lines, LNCaP and MDA-PCa 2B, that had ETV1 outlier expression. Through distinct mechanisms, the entire ETV1 locus (7p21) is rearranged to a 1.5-megabase prostate-specific region at 14q13.3-14q21.1 in both LNCaP cells (cryptic insertion) and MDA-PCa 2B cells (balanced translocation). Because the common factor of these rearrangements is aberrant ETV1 overexpression, we recapitulated this event in vitro and in vivo, demonstrating that ETV1 overexpression in benign prostate cells and in the mouse prostate confers neoplastic phenotypes. Identification of distinct classes of ETS gene rearrangements demonstrates that dormant oncogenes can be activated in prostate cancer by juxtaposition to tissue-specific or ubiquitously active genomic loci. Subversion of active genomic regulatory elements may serve as a more generalized mechanism for carcinoma development. Furthermore, the identification of androgen-repressed and insensitive 5' fusion partners may have implications for the anti-androgen treatment of advanced prostate cancer.

The aromatase inhibitors Anastrozole, Letrozole (type 2 nonsteroidal aromatase inhibitors: n-SAI) and Exemestane (type 1 steroidal aromatase inactivator) are used respectively as first- and second-line hormonal therapy in postmenopausal metastatic breast cancer women. Few clinical data are published on the sequential use of different classes of aromatase inhibitors.We report an analysis on 30 postmenopausal metastatic breast cancer women treated between January 2000 and May 2002 in 2 Italian Oncology Institutions with the hormonal sequence n-SAI (Anastrozole, Letrozole) --Exemestane.When receiving n-SAI (Anastrozole 8 patients and Letrozole 22 patients), 1 out of 30 women achieved a partial response, 20 of 30 patients no change (NC)or =6 months. The analysis of the entire population treated with Exemestane showed an overall clinical benefit (CB) of 46.6 percent (14/30) with a median duration of 12 months (95%CI 6-25) and a median time to progression (TTP) of 4 months (95%CI 1-25).These data confirm a partial lack of cross-resistance between n-SAI --Exemestane given in sequence.

Cellular senescence is a stable growth arrest that constrains cell cycle progression in case proliferation becomes aberrant, thus limiting tumorigenesis. Oncogenic mutations and loss of tumor suppressor genes that cause uncontrolled cell-cycle progression are required events in tumor development. Nevertheless, many of these genetic alterations retain an intrinsic tumor-suppressive potential that gives rise to oncogene-induced senescence and tumor suppressor loss-induced senescence. Interestingly, many evidences support the idea that a strong interplay occurs between senescence, cancer cells, and tumor infiltrating immune populations, thus opening at the possibility to tune such interplay for cancer treatment. Indeed, tumor infiltrating T helper 1 cells can drive senescence in cancers in a cytokine-induced manner, by secreting IFNγ and TNFα in the tumor microenvironment. In addition, we recently described a model where Pten loss induced senescence is hindered in prostate tumor by non-cell-autonomous mechanisms. Our study support a model where tumor-infiltrating CD11b+Gr-1+ myeloid cells paracrinally triggers tumor senescence evasion in the prostate of Pten null mice, eventually promoting tumor progression. These findings we’ll be discussed. Interestingly, we will present new evidences from our lab indicating that M1 macrophages are polarized to the M2 phenotype in both Pten pc-/- and that treatments that interfere with the M1-M2 polarization and switch the skewing to the M1 polarization profile can induce senescence in Pten; Trp53pc-/- invasive prostate cancer tumours thereby arresting tumour progression. These findings open at the possibility that M1 directly control senescence in tumor cells. Finally, we have identified a gene expression signature that distinguishes myeloid infiltration in tumors and can be used as a predictive marker for tumor progression in prostate cancer patients. These evidences we’ll be also discussed. Citation Format: Diletta Di Mitri, JingJing Chen, Andrea Alimonti. Targeting the tumor immune response for pro-senescence therapy in prostate cancer. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 2346. doi:10.1158/1538-7445.AM2015-2346

The incidence of kidney tumors in USA and Europe (in particular, Central Europe and Italy) has been dramatically increasing since the 1970s, possibly as a consequence of ongoing environmental pollution. Environmental factors have been considered responsible for at least 80% of the incidence of neoplastic diseases. To shed some light on this issue, the amounts of Cd and Pb were measured in neoplastic tissue and adjacent normal part of kidney excised for carcinoma and compared with those in renal tissues of fetuses, newborns and subjects that died of non-neoplastic diseases. Cd and Pb were determined by Inductively Coupled Plasma Atomic Emission Spectrometry and Atomic Absorption Spectrometry with Electrothermal Atomization. Metallothionein immunoperoxidase staining technique was used to localize the accumulation of Cd and Zn in the nephrons. Content of Cd and Pb in kidneys of fetuses and newborns was extremely low. However, it was significantly increased in adjacent-normal tissues of kidneys with carcinomas, and significantly higher compared to kidneys of individuals that died of non-neoplastic diseases. In tumoral tissues of the excised kidneys, Cd content was very low, while that of Pb significantly elevated. High amounts of Cd and Pb in the adjacent-normal parts of kidneys with carcinomas are suggestive of possible, individual or synergistic, effects of these pollutants on enzymatic systems, priming an oncogenic pathway. Detection of metallothioneins, primary ligands of Cd, exclusively in the cells of proximal tubuli, i.e. wherein renal carcinoma develops in over 80% of cases, strongly supports the assumption that Cd exerts a carcinogenic effect.

Background: To evaluate the modifications of circulating angiogenic factors, metalloproteinases and acute-phase cytokines after the first single zoledronic acid (ZA) intravenous infusion. Experimental Design:Eighteen consecutive breast cancer patients with bone metastases were evaluated for circulating levels of vascular endothelial growth factor (VEGF), basic fibroblast growth factor (bFGF), metalloproteinase 1 (MMP-1), metalloproteinase 2 (MMP-2), interleukins 1β, 6 and 8 (IL-1β, IL-6, IL-8), interferon γ, tumor necrosis factor α (TNF-α) and transforming growth factor β1 just before and 2 and 7 days after ZA infusion. Results: The MMP-2 basal value showed a statisticallysignificant decrease 48 h after ZA (p = 0.01), being at 7 days higher than the day 2 value (p = 0.03). The VEGF basal value showed a statisticallysignificant decrease 48 h after ZA infusion (p = 0.03), increasing above the basal level at 7 days (p = 0.07). The bFGF basal level almost significantly decreased 2 days after infusion (p = 0.06), being at 7 days higher than the basal value (p = 0.09). Comparing the day 2 values with basal ones, the linear regression model showed a significantpositive correlation between IL-8 and bFGF (p = 0.02), IL-8 and TNF-α (p < 0.0001), bFGF and TNF-α (p = 0.01), MMP-1 and TNF-α (p = 0.02). Conclusions: ZA could exert an antiangiogenic activity and inhibition of tumor cell bone invasiveness by a transient reduction of VEGF, bFGF and MMP-2 circulating levels after infusion.

Background. Irinotecan is a selective inhibitor of topoisomerase I, an enzyme part of the replication and transcription system of DNA. Irinotecan is employed, with different modalities, in the treatment of metastatic colorectal cancer, and recently it has been officially approved in association with fluorouracil (FU) and leucovorin (LV) as a first-line option in metastatic colorectal cancer. Results. One of the problems linked to the administration of this drug is the high intestinal toxicity, which constitutes its dose limiting toxicity (DLT). In routine practice, loperamide is employed as symptomatic drug for the treatment of CPT-11-induced diarrhoea, but is not completely adequate to control the problem. The role of the intestinal bacterial microflora in the pathogenesis of CPT-11-induced intestinal toxicity has been recently discovered. The active metabolite of CPT-11, SN38, is generated from CPT-11 by sieric carboxylesterase, and subsequently conjugated to SN38-G by hepatic UDP–glucuronyltransferase. SN38-G is the inactive metabolite of CPT-11 and is excreted into the small intestine, from which it is eliminated in the faeces. Some studies have shown the ability of intestinal bacterial β-glucoronidases to transform SN38-G into SN38, causing direct damage to the intestinal mucosa. Thus, alternative strategies such as intestinal alkalinization and anti-cyclooxygenase 2 (COX-2) therapy have been explored. Conclusions. In this review, we will illustrate the mechanisms which cause the CPT-11-induced diarrhoea and the potential measures available to prevent it.

Introduction and Aim of Study: Marine derived compounds have been explored and considered as possible antitumor agents. Some natural products from marine organisms are currently in clinical trials, such as: Eribulin, an analogue of halichondrin B, isolated from the marine sponge Halichondria okadai, which is approved by FDA for the treatment of metastatic breast cancer; and Trabectedin, from Ecteinascidia turbinate, approved for treatment of soft tissue sarcomas and ovarian cancer also in Europe. In this study we analyzed extracts of the sponge Cribrochalina vasculum for the inhibition of tumor growth and hence hold potential to be used as novel antitumor agents. Material and Methods: Extracts were obtained from the Caribbean sponge Cribrochalina vasculum. The tumor specific cytotoxicity of the extracts was determined by MTT assay using non-small cell lung carcinoma (NSCLC) cells and normal lung fibroblasts WI-38. The active crude extract showing tumor specific toxicity was fractionated by HPLC to obtain pure compounds and their structures elucidated by physiochemical methods. Various concentrations of the pure compounds were rescreened on several non-small and small lung carcinoma cell lines (NSCLC and SCLC), on ovarian carcinoma cells as well as on normal lung fibroblasts WI-38. Induction of apoptosis was assessed as caspase-3, caspase-9 and PARP cleavage on western blot. To detect and quantify apoptotic morphology, cells treated were stained with DAPI and examined using a fluorescence microscope. Conformational change in proapoptotic protein Bak in response to treatment for 16 h was examined in NSCLC U-1810 using flow cytometric analyses. Cell cycle distribution was examined in NSCLC and diploid fibroblast by propidium iodide (PI) staining, using a flow cytometer. Results: Screening of crude extracts from C. vasculum identified certain extracts that showed tumor specific toxicity while having no effect on diploid fibroblasts. From these extracts purified compounds were identified which showed antitumor activity in both NSCLC, SCLC as well as in ovarian carcinoma cells. The purified compounds were found to cause a time dependent increase in activation of apoptotic signaling in NSCLC cells, but not in normal fibroblasts. Thus exposure of NSCLC cells to these compounds caused cleavage of caspase-9, caspase-3 and PARP, as well as induction of apoptotic cell morphology and Bak conformational change. Cell cycle analyses revealed that these compounds caused a pronounced block in the G2/M phase of the cell cycle of NSCLC cells whereas normal fibroblasts were not influenced. In vivo analyses of the compounds in mice tumor models is ongoing. Conclusion: We have identified, by screening extracts from the sponge C. vasculum, compounds that hold promise as antitumor agents in NSCLC and SCLC as well as in ovarian carcinoma. Further work aims to identify putative cellular targets of these compounds within tumor cells. Citation Information: Mol Cancer Ther 2013;12(11 Suppl):A170. Citation Format: Ana Zovko, Kristina Viktorsson, Petra Hååg, Micha Ilan, Dimitry Kovalerchick, Shmuel Carmeli, Andrea Alimonti, Rolf Lewensohn. Analysis of marine sponge Cribrochalina vasculum compounds demonstrate selective antitumor properties by activation of intrinsic apoptotic signaling and impaired growth factor receptor signaling cascades. [abstract]. In: Proceedings of the AACR-NCI-EORTC International Conference: Molecular Targets and Cancer Therapeutics; 2013 Oct 19-23; Boston, MA. Philadelphia (PA): AACR; Mol Cancer Ther 2013;12(11 Suppl):Abstract nr A170.