Retinoic acid receptor activation reprograms senescence response and enhances anti-tumor activity of natural killer cells.

Cellular senescence can exert dual effects in tumors, either suppressing or promoting tumor progression. The senescence-associated secretory phenotype (SASP), released by senescent cells, plays a crucial role in this dichotomy. Consequently, the clinical challenge lies in developing therapies that safely enhance senescence in cancer, favoring tumor-suppressive SASP factors over tumor-promoting ones. Here, we identify the retinoic-acid-receptor (RAR) agonist adapalene as an effective pro-senescence compound in prostate cancer (PCa). Reactivation of RARs triggers a robust senescence response and a tumor-suppressive SASP. In preclinical mouse models of PCa, the combination of adapalene and docetaxel promotes a tumor-suppressive SASP that enhances natural killer (NK) cell-mediated tumor clearance more effectively than either agent alone. This approach increases the efficacy of the allogenic infusion of human NK cells in mice injected with human PCa cells, suggesting an alternative therapeutic strategy to stimulate the anti-tumor immune response in "immunologically cold" tumors.

Genetic ablation of ketohexokinase C isoform impairs pancreatic cancer development.

Although dietary fructose is associated with an elevated risk for pancreatic cancer, the underlying mechanisms remain elusive. Here, we report that ketohexokinase (KHK), the rate-limiting enzyme of fructose metabolism, is a driver of PDAC development. We demonstrate that fructose triggers KHK and induces fructolytic gene expression in mouse and human PDAC. Genetic inactivation of KhkC enhances the survival of KPC-driven PDAC even in the absence of high fructose diet. Furthermore, it decreases the viability, migratory capability, and growth of KPC cells in a cell autonomous manner. Mechanistically, we demonstrate that genetic ablation of KHKC strongly impairs the activation of KRAS-MAPK pathway and of rpS6, a downstream target of mTORC signaling. Moreover, overexpression of KHKC in KPC cells enhances the downstream KRAS pathway and cell viability. Our data provide new insights into the role of KHK in PDAC progression and imply that inhibiting KHK could have profound implications for pancreatic cancer therapy.

The potential role of the microbiota in prostate cancer pathogenesis and treatment.

The human body hosts a complex and dynamic population of trillions of microorganisms - the microbiota - which influences the body in homeostasis and disease, including cancer. Several epidemiological studies have associated specific urinary and gut microbial species with increased risk of prostate cancer; however, causal mechanistic data remain elusive. Studies have associated bacterial generation of genotoxins with the occurrence of TMPRSS2-ERG gene fusions, a common, early oncogenic event during prostate carcinogenesis. A subsequent study demonstrated the role of the gut microbiota in prostate cancer endocrine resistance, which occurs, at least partially, through the generation of androgenic steroids fuelling oncogenic signalling via the androgen receptor. These studies present mechanistic evidence of how the host microbiota might be implicated in prostate carcinogenesis and tumour progression. Importantly, these findings also reveal potential avenues for the detection and treatment of prostate cancer through the profiling and modulation of the host microbiota. The latter could involve approaches such as the use of faecal microbiota transplantation, prebiotics, probiotics, postbiotics or antibiotics, which can be used independently or combined with existing treatments to reverse therapeutic resistance and improve clinical outcomes in patients with prostate cancer.

The Akt/mTOR and MNK/eIF4E pathways rewire the prostate cancer translatome to secrete HGF, SPP1 and BGN and recruit suppressive myeloid cells.

Cancer is highly infiltrated by myeloid-derived suppressor cells (MDSCs). Currently available immunotherapies do not completely eradicate MDSCs. Through a genome-wide analysis of the translatome of prostate cancers driven by different genetic alterations, we demonstrate that prostate cancer rewires its secretome at the translational level to recruit MDSCs. Among different secreted proteins released by prostate tumor cells, we identified Hgf, Spp1 and Bgn as the key factors that regulate MDSC migration. Mechanistically, we found that the coordinated loss of Pdcd4 and activation of the MNK/eIF4E pathways regulate the mRNAs translation of Hgf, Spp1 and Bgn. MDSC infiltration and tumor growth were dampened in prostate cancer treated with the MNK1/2 inhibitor eFT508 and/or the AKT inhibitor ipatasertib, either alone or in combination with a clinically available MDSC-targeting immunotherapy. This work provides a therapeutic strategy that combines translation inhibition with available immunotherapies to restore immune surveillance in prostate cancer.

SF3B1 facilitates HIF1-signaling and promotes malignancy in pancreatic cancer.

Mutations in the splicing factor SF3B1 are frequently occurring in various cancers and drive tumor progression through the activation of cryptic splice sites in multiple genes. Recent studies also demonstrate a positive correlation between the expression levels of wild-type SF3B1 and tumor malignancy. Here, we demonstrate that SF3B1 is a hypoxia-inducible factor (HIF)-1 target gene that positively regulates HIF1 pathway activity. By physically interacting with HIF1α, SF3B1 facilitates binding of the HIF1 complex to hypoxia response elements (HREs) to activate target gene expression. To further validate the relevance of this mechanism for tumor progression, we show that a reduction in SF3B1 levels via monoallelic deletion of Sf3b1 impedes tumor formation and progression via impaired HIF signaling in a mouse model for pancreatic cancer. Our work uncovers an essential role of SF3B1 in HIF1 signaling, thereby providing a potential explanation for the link between high SF3B1 expression and aggressiveness of solid tumors.

Single-cell transcriptomics identifies Mcl-1 as a target for senolytic therapy in cancer.

Cells subjected to treatment with anti-cancer therapies can evade apoptosis through cellular senescence. Persistent senescent tumor cells remain metabolically active, possess a secretory phenotype, and can promote tumor proliferation and metastatic dissemination. Removal of senescent tumor cells (senolytic therapy) has therefore emerged as a promising therapeutic strategy. Here, using single-cell RNA-sequencing, we find that senescent tumor cells rely on the anti-apoptotic gene Mcl-1 for their survival. Mcl-1 is upregulated in senescent tumor cells, including cells expressing low levels of Bcl-2, an established target for senolytic therapy. While treatment with the Bcl-2 inhibitor Navitoclax results in the reduction of metastases in tumor bearing mice, treatment with the Mcl-1 inhibitor S63845 leads to complete elimination of senescent tumor cells and metastases. These findings provide insights on the mechanism by which senescent tumor cells survive and reveal a vulnerability that can be exploited for cancer therapy.

miR-802 Suppresses Acinar-to-Ductal Reprogramming During Early Pancreatitis and Pancreatic Carcinogenesis.

BACKGROUND & AIMS: Pancreatic ductal adenocarcinoma (PDAC) is a highly aggressive tumor that is almost uniformly lethal in humans. Activating mutations of KRAS are found in >90% of human PDACs and are sufficient to promote acinar-to-ductal metaplasia (ADM) during tumor initiation. The roles of miRNAs in oncogenic Kras-induced ADM are incompletely understood. METHODS: The Ptf1aCre/+LSL-KrasG12D/+ and Ptf1aCre/+LSL-KrasG12D/+LSL-p53R172H/+ and caerulein-induced acute pancreatitis mice models were used. mir-802 was conditionally ablated in acinar cells to study the function of miR-802 in ADM. RESULTS: We show that miR-802 is a highly abundant and acinar-enriched pancreatic miRNA that is silenced during early stages of injury or oncogenic KrasG12D-induced transformation. Genetic ablation of mir-802 cooperates with KrasG12D by promoting ADM formation. miR-802 deficiency results in de-repression of the miR-802 targets Arhgef12, RhoA, and Sdc4, activation of RhoA, and induction of the downstream RhoA effectors ROCK1, LIMK1, COFILIN1, and EZRIN, thereby increasing F-actin rearrangement. mir-802 ablation also activates SOX9, resulting in augmented levels of ductal and attenuated expression of acinar identity genes. Consistently with these findings, we show that this miR-802-RhoA-F-actin network is activated in biopsies of pancreatic cancer patients and correlates with poor survival. CONCLUSIONS: We show miR-802 suppresses pancreatic cancer initiation by repressing oncogenic Kras-induced ADM. The role of miR-802 in ADM fills the gap in our understanding of oncogenic Kras-induced F-actin reorganization, acinar reprogramming, and PDAC initiation. Modulation of the miR-802-RhoA-F-actin network may be a new strategy to interfere with pancreatic carcinogenesis.

Multiparametric magnetic resonance imaging of the prostate underestimates tumour volume of small visible lesions.

OBJECTIVE: To assess the relationship between the volume of the index lesion (IL) measured at multiparametric magnetic resonance imaging (mpMRI; MRIvol) and at radical prostatectomy (RPvol), stratifying it according to Prostate Imaging-Reporting and Data System (PI-RADS) score. PATIENTS AND METHODS: We identified 332 men with a positive mpMRI (single lesion with PI-RADS ≥3) who underwent systematic plus targeted biopsy and subsequent RP at two tertiary referral centres between 2013 and 2018. All mpMRIs were reviewed by experienced radiologists using PI-RADS scores. The study outcome was to assess the relationship between MRIvol (based on planimetry from MRI sequence best showing tumour) and RPvol (based on tumour involved area of each RP pathology slice). To achieve this endpoint, we performed a multivariable linear regression analysis (LRA) to predict RPvol using PI-RADS, prostate-specific antigen level, prostate volume, age, digital rectal examination, Gleason score at MRI-targeted biopsy, biopsy history and time from mpMRI to RP as covariates. Non-parametric locally estimated scatterplot smoothing (LOESS) function was used to graphically explore the relationship between MRIvol and RPvol, stratifying for PI-RADS score. RESULTS: Overall, 24%, 49% and 27% of men had visible PI-RADS 3, 4 and 5 lesions at mpMRI. The median (interquartile range [IQR]) MRIvol and RPvol were 0.67 (0.29-1.76) mL and 1.39 (0.58-4.23) mL. At LRA, MRIvol was significantly correlated with a RPvol underestimation (slope: 2.4, 95% confidence interval [CI] 0.1-46.3). The non-parametric LOESS analysis showed a non-linear relationship between MRIvol and RPvol. Significant underestimation was reported across all volumes with the highest differences between MRIvol and RPvol in the low volume range (<2 mL), where RPvol almost doubled MRIvol. A similar effect was observed across all PI-RADS scores subgroups. CONCLUSIONS: In the present study, mpMRI significantly underestimated the exact volume of the IL, especially for small visible lesions, regardless of PI-RADS score. This should be considered when planning tailored focal therapy approaches often delivered to men with smaller prostatic lesions.

Age and gleason score upgrading between prostate biopsy and radical prostatectomy: Is this still true in the multiparametric resonance imaging era?

INTRODUCTION: Several studies have invariably shown that the risk of Grade Group (GG) upgrading between biopsy and radical prostatectomy (RP) is higher in elderly men. Whether this is due to a real biological effect or to a diagnostic bias is still unknown. We hypothesized that the introduction of multiparametric magnetic resonance imaging (MRI) has improved the diagnostic accuracy of PCa detection in older men thus reducing the risk of GG upgrading at RP reported in the pre-MRI era. MATERIALS AND METHODS: We selected 424 men who received a systematic plus targeted biopsy for a positive MRI and subsequent RP at two referral centers between 2013 and 2019. Upgrading was defined as an increase in GG at final pathology as compared to biopsy. Multivariable logistic regressions tested the risk of upgrading over increasing age according to any upgrading definition and after stratifying definitions according to GG group and biopsy type. Non-parametric functions explored the relationship between age and upgrading rate. RESULTS: Median rate of upgrading was 17%. In multivariable models, while age was not associated with increased risk of GG upgrading (p=0.4). At non-parametric analyses, probability of upgrading slightly decreased with age, without reaching statistical significance. In subgroup analyses according to different upgrading definition and to biopsy type, age did not predict higher risk of upgrading regardless of outcome definitions (GG 1 to 2 P = 0.1; GG 2 to 3 P = 0.2; GG 3 to 4-5 P = 0.2) and in GG detected at TBx (OR 0.998, P = 0.8). CONCLUSIONS: We showed that use of MRI has obliterated the association between older age and increased risk of upgrading mainly due to improved diagnostic approaches in this group of men. Therefore, it is likely that the effect of age and GG upgrading reported in previous studies in elderly men was due to misdiagnosis and lead-time bias in the pre-MRI era.

Senescence Reprogramming by TIMP1 Deficiency Promotes Prostate Cancer Metastasis.

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.

CDCP1 overexpression drives prostate cancer progression and can be targeted in vivo.

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.

Publisher Correction: Compartmentalized activities of the pyruvate dehydrogenase complex sustain lipogenesis in prostate cancer.

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.

Compartmentalized activities of the pyruvate dehydrogenase complex sustain lipogenesis in prostate cancer.

The mechanisms by which mitochondrial metabolism supports cancer anabolism remain unclear. Here, we found that genetic and pharmacological inactivation of pyruvate dehydrogenase A1 (PDHA1), a subunit of the pyruvate dehydrogenase complex (PDC), inhibits prostate cancer development in mouse and human xenograft tumor models by affecting lipid biosynthesis. Mechanistically, we show that in prostate cancer, PDC localizes in both the mitochondria and the nucleus. Whereas nuclear PDC controls the expression of sterol regulatory element-binding transcription factor (SREBF)-target genes by mediating histone acetylation, mitochondrial PDC provides cytosolic citrate for lipid synthesis in a coordinated manner, thereby sustaining anabolism. Additionally, we found that PDHA1 and the PDC activator pyruvate dehydrogenase phosphatase 1 (PDP1) are frequently amplified and overexpressed at both the gene and protein levels in prostate tumors. Together, these findings demonstrate that both mitochondrial and nuclear PDC sustain prostate tumorigenesis by controlling lipid biosynthesis, thus suggesting this complex as a potential target for cancer therapy.

Correction of gene model annotations improves isoform abundance estimates: the example of ketohexokinase ( Khk).

Next generation sequencing protocols such as RNA-seq have made the genome wide characterization of the transcriptome a crucial part of many research projects in biology. Analyses of the resulting data provide key information on gene expression and in certain cases on exon or isoform usage. The emergence of transcript quantification software such as Salmon has enabled researchers to efficiently estimate isoform and gene expressions across the genome while tremendously reducing the necessary computational power. Although overall gene expression estimations were shown to be accurate, isoform expression quantifications appear to be a more challenging task. Low expression levels and uneven or insufficient coverage were reported as potential explanations for inconsistent estimates. Here, through the example of the ketohexokinase ( Khk) gene in mouse, we demonstrate that the use of an incorrect gene annotation can also result in erroneous isoform quantification results. Manual correction of the input Khk gene model provided a much more accurate estimation of relative Khk isoform expression when compared to quantitative PCR (qPCR measurements). In particular, removal of an unexpressed retained intron and a proper adjustment of the 5' and 3' untranslated regions both had a strong impact on the correction of erroneous estimates. Finally, we observed a better concordance in isoform quantification between datasets and sequencing strategies when relying on the newly generated Khk annotations. These results highlight the importance of accurate gene models and annotations for correct isoform quantification and reassert the need for orthogonal methods of estimation of isoform expression to confirm important findings.

A chemogenomic screening identifies CK2 as a target for pro-senescence therapy in PTEN-deficient tumours.

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.

Src inhibitors modulate frataxin protein levels.

Defective expression of frataxin is responsible for the inherited, progressive degenerative disease Friedreich's Ataxia (FRDA). There is currently no effective approved treatment for FRDA and patients die prematurely. Defective frataxin expression causes critical metabolic changes, including redox imbalance and ATP deficiency. As these alterations are known to regulate the tyrosine kinase Src, we investigated whether Src might in turn affect frataxin expression. We found that frataxin can be phosphorylated by Src. Phosphorylation occurs primarily on Y118 and promotes frataxin ubiquitination, a signal for degradation. Accordingly, Src inhibitors induce accumulation of frataxin but are ineffective on a non-phosphorylatable frataxin-Y118F mutant. Importantly, all the Src inhibitors tested, some of them already in the clinic, increase frataxin expression and rescue the aconitase defect in frataxin-deficient cells derived from FRDA patients. Thus, Src inhibitors emerge as a new class of drugs able to promote frataxin accumulation, suggesting their possible use as therapeutics in FRDA.

Interaction of CDCP1 with HER2 enhances HER2-driven tumorigenesis and promotes trastuzumab resistance in breast cancer.

Understanding 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.

Enhancing chemotherapy efficacy in Pten-deficient prostate tumors by activating the senescence-associated antitumor immunity.

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.

Tumour-infiltrating Gr-1+ myeloid cells antagonize senescence in cancer.

Aberrant activation of oncogenes or loss of tumour suppressor genes opposes malignant transformation by triggering a stable arrest in cell growth, which is termed cellular senescence. This process is finely tuned by both cell-autonomous and non-cell-autonomous mechanisms that regulate the entry of tumour cells to senescence. Whether tumour-infiltrating immune cells can oppose senescence is unknown. Here we show that at the onset of senescence, PTEN null prostate tumours in mice are massively infiltrated by a population of CD11b(+)Gr-1(+) myeloid cells that protect a fraction of proliferating tumour cells from senescence, thus sustaining tumour growth. Mechanistically, we found that Gr-1(+) cells antagonize senescence in a paracrine manner by interfering with the senescence-associated secretory phenotype of the tumour through the secretion of interleukin-1 receptor antagonist (IL-1RA). Strikingly, Pten-loss-induced cellular senescence was enhanced in vivo when Il1ra knockout myeloid cells were adoptively transferred to PTEN null mice. Therapeutically, docetaxel-induced senescence and efficacy were higher in PTEN null tumours when the percentage of tumour-infiltrating CD11b(+)Gr-1(+) myeloid cells was reduced using an antagonist of CXC chemokine receptor 2 (CXCR2). Taken together, our findings identify a novel non-cell-autonomous network, established by innate immunity, that controls senescence evasion and chemoresistance. Targeting this network provides novel opportunities for cancer therapy.