Stratification of Patients with Renal Cell Carcinoma by the Abundance of Sarcomatoid Features Reveals Differences in Survival and the Underlying Pathobiology.

Sarcomatoid renal cell carcinoma (sRCC) is histologically heterogeneous, with variable sarcomatoid amounts intermixed within epithelial carcinoma. However, the current classification for this aggressive disease is homogeneous and agnostic to the sarcomatoid proportion. We investigated whether sRCC subclassification has prognostic value and can reveal the biology underlying dedifferentiation and its clinical aggressiveness. On the basis of the intratumoral abundance of sarcomatoid features, cases were classified as sarcomatoid-high (≥10% sarcomatoid features) or sarcomatoid-low (<10% sarcomatoid features) in a cohort of 104 consecutive patients with sRCC undergoing nephrectomy at a single center. In comparison to sarcomatoid-low patients (n = 52), sarcomatoid-high patients (n = 52) had significantly shorter overall survival (median 14.5 vs 62.9 mo; p < 0.001), which was confirmed on multivariable analysis, and significantly shorter median metastasis-free survival among patients with clinically localized disease (10.7 vs 39.0 mo; p = 0.043). Transcriptomic analyses of 45 sRCC tumors revealed significant upregulation of nine hallmark pathways related to cell cycle/proliferation, epithelial-to-mesenchymal transition, reactive oxidative species, and interferon-α signaling among sarcomatoid-high (n = 24) versus sarcomatoid-low (n = 21) tumors. Categorization into transcriptomic clusters revealed predominance of proliferative, inflammatory, and immune effector phenotypes among sarcomatoid-high tumors, versus a hypoxia/angiogenesis phenotype among sarcomatoid-low tumors. Overall, these findings indicate prognostic value for sRCC subclassification into high versus low sarcomatoid groups and highlight key biology underlying the differences in clinical outcomes. PATIENT SUMMARY: Sarcomatoid renal cell carcinoma (sRCC) is a highly aggressive form of kidney cancer. The percentage of sarcomatoid features varies among tumors, but sRCC is still defined as a single kidney cancer type. Our results show that grouping patients according to their percentage of sarcomatoid features improves prediction of whether their tumors will become metastatic or lethal, and reveal molecular differences that may be important for this disease. Future assignment of sRCC to high and low sarcomatoid groups may help in guiding research and patient management.

Androgen deprivation triggers a cytokine signaling switch to induce immune suppression and prostate cancer recurrence.

Androgen deprivation therapy (ADT) is an effective but not curative treatment for advanced and recurrent prostate cancer (PC). We investigated the mechanisms controlling the response to androgen-deprivation by surgical castration in genetically-engineered mouse models (GEMM) of PC, using high frequency ultrasound imaging to rigorously measure tumor volume. Castration initially causes almost all tumors to shrink in volume, but many tumors subsequently recur within 5-10 weeks. Blockade of tumor necrosis factor (TNF) signaling a few days in advance of castration surgery, using a TNFR2 ligand trap, prevents regression in a PTEN-deficient GEMM. Following tumor regression, a basal stem cell-like population within the tumor increases along with TNF protein levels. Tumor cell lines in culture recapitulate these in vivo observations, suggesting that basal stem cells are the source of TNF. When TNF signaling blockade is administered immediately prior to castration, tumors regress but recurrence is prevented, implying that a late wave of TNF secretion within the tumor, which coincides with the expression of NFkB regulated genes, drives recurrence. The inhibition of signaling downstream of one NFkB-regulated protein, chemokine C-C motif ligand 2 (CCL2), prevents post-castration tumor recurrence, phenocopying post-castration (late) TNF signaling blockade. CCL2 was originally identified as a macrophage chemoattractant and indeed at late times after castration gene sets related to chemotaxis and migration are up-regulated. Importantly, enhanced CCL2 signaling during the tumor recurrence phase coincides with an increase in pro-tumorigenic macrophages and a decrease in CD8 T cells, suggesting that recurrence is driven at least in part by tumor immunosuppression. In summary, we demonstrate that a therapy-induced switch in TNF signaling, a consequence of the increased stem cell-like character of the residual tumor cells surviving ADT, induces an immunosuppressive tumor microenvironment and concomitant tumor recurrence.

CD8+ T cell metabolic flexibility elicited by CD28-ARS2 axis-driven alternative splicing of PKM supports antitumor immunity.

Metabolic flexibility has emerged as a critical determinant of CD8+ T-cell antitumor activity, yet the mechanisms driving the metabolic flexibility of T cells have not been determined. In this study, we investigated the influence of the nuclear cap-binding complex (CBC) adaptor protein ARS2 on mature T cells. In doing so, we discovered a novel signaling axis that endows activated CD8+ T cells with flexibility of glucose catabolism. ARS2 upregulation driven by CD28 signaling reinforced splicing factor recruitment to pre-mRNAs and affected approximately one-third of T-cell activation-induced alternative splicing events. Among these effects, the CD28-ARS2 axis suppressed the expression of the M1 isoform of pyruvate kinase in favor of PKM2, a key determinant of CD8+ T-cell glucose utilization, interferon gamma production, and antitumor effector function. Importantly, PKM alternative splicing occurred independently of CD28-driven PI3K pathway activation, revealing a novel means by which costimulation reprograms glucose metabolism in CD8+ T cells.

Rate of castration-induced prostate stroma regression is reduced in a mouse model of benign prostatic hyperplasia.

Benign prostatic hyperplasia (BPH) is a non-neoplastic proliferative disease producing lower urinary tract symptoms related to the resulting enlarged prostate. BPH is pathologically characterized by hyperplastic growth in both epithelial and stromal compartments. Androgen signaling is essential for prostate function and androgen blockade is the second-line medical therapy to relieve symptoms of BPH. Here we examined the prostates of probasin promoter-driven prolactin (Pb-PRL) transgenic mice, a robust model of BPH that spontaneously develops prostate enlargement, to investigate prostate regression in response to surgical castration. Serial ultrasound imaging demonstrated very uniform self-limited growth of Pb-PRL prostate volume that is consistent with the benign, limited cellular proliferation characteristic of BPH and that contrasts with the highly variable, exponential growth of murine prostate cancer models. Castration elicited only a partial reduction in prostate volume, relative to castration-induced regression of the normal prostate gland. The anti-androgen finasteride induced a diminished reduction of Pb-PRL prostate volume versus castration. The limited extent of Pb-PRL mouse prostate volume regression correlated with the initial volume of the stromal compartment, suggesting a differential sensitivity of the epithelial and stromal compartments to androgen withdrawal. Indeed, two-dimensional morphometric analyses revealed a distinctly reduced rate of regression for the stromal compartment in Pb-PRL mice. The myofibroblast component of the Pb-PRL prostate stroma appeared normal, but the stromal compartment contained more fibroblasts and extracellular collagen deposition. Like normal prostate, the rate of regression of the Pb-PRL prostate was partially dependent on TGFß and TNF signaling, but unlike the normal prostate, the extent of castration-induced regression was not affected by TGFß or TNF blockade. Our studies show that androgen deprivation can effectively reduce the overall volume of hyperplastic prostate, but the stromal compartment is relatively resistant, suggesting additional therapies might be required to offer an effective treatment for the clinical manifestations of BPH.

Combined BRCA2 and MAGEC3 Expression Predict Outcome in Advanced Ovarian Cancers.

Like BRCA2, MAGEC3 is an ovarian cancer predisposition gene that has been shown to have prognostic significance in ovarian cancer patients. Despite the clinical significance of each gene, no studies have been conducted to assess the clinical significance of their combined expression. We therefore sought to determine the relationship between MAGEC3 and BRCA2 expression in ovarian cancer and their association with patient characteristics and outcomes. Immunohistochemical staining was quantitated on tumor microarrays of human tumor samples obtained from 357 patients with epithelial ovarian cancer to ascertain BRCA2 expression levels. In conjunction with our previously published MAGEC3 expression data, we observed a weak inverse correlation of MAGEC3 with BRCA2 expression (r = −0.15; p < 0.05) in cases with full-length BRCA2. Patients with optimal cytoreduction, loss of MAGEC3, and detectable BRCA2 expression had better overall (median OS: 127.9 vs. 65.3 months, p = 0.035) and progression-free (median PFS: 85.3 vs. 18.8 months, p = 0.002) survival compared to patients that were BRCA2 expressors with MAGEC3 normal levels. Our results suggest that combined expression of MAGEC3 and BRCA2 serves as a better predictor of prognosis than each marker alone.

Mitigating the prevalence and function of myeloid-derived suppressor cells by redirecting myeloid differentiation using a novel immune modulator.

BACKGROUND: Immune suppression is common in neoplasia and a major driver is tumor-induced myeloid dysfunction. Yet, overcoming such myeloid cell defects remains an untapped strategy to reverse suppression and improve host defense. Exposure of bone marrow progenitors to heightened levels of myeloid growth factors in cancer or following certain systemic treatments promote abnormal myelopoiesis characterized by the production of myeloid-derived suppressor cells (MDSCs) and a deficiency in antigen-presenting cell function. We previously showed that a novel immune modulator, termed 'very small size particle' (VSSP), attenuates MDSC function in tumor-bearing mice, which was accompanied by an increase in dendritic cells (DCs) suggesting that VSSP exhibits myeloid differentiating properties. Therefore, here, we addressed two unresolved aspects of the mechanism of action of this unique immunomodulatory agent: (1) does VSSP alter myelopoiesis in the bone marrow to redirect MDSC differentiation toward a monocyte/macrophage or DC fate? and (2) does VSSP mitigate the frequency and suppressive function of human tumor-induced MDSCs? METHODS: To address the first question, we first used a murine model of granulocyte-colony stimulating factor-driven emergency myelopoiesis following chemotherapy-induced myeloablation, which skews myeloid output toward MDSCs, especially the polymorphonuclear (PMN)-MDSC subset. Following VSSP treatment, progenitors and their myeloid progeny were analyzed by immunophenotyping and MDSC function was evaluated by suppression assays. To strengthen rigor, we validated our findings in tumor-bearing mouse models. To address the second question, we conducted a clinical trial in patients with metastatic renal cell carcinoma, wherein 15 patients were treated with VSSP. Endpoints in this study included safety and impact on PMN-MDSC frequency and function. RESULTS: We demonstrated that VSSP diminished PMN-MDSCs by shunting granulocyte-monocyte progenitor differentiation toward monocytes/macrophages and DCs with heightened expression of the myeloid-dependent transcription factors interferon regulatory factor-8 and PU.1. This skewing was at the expense of expansion of granulocytic progenitors and rendered the remaining MDSCs less suppressive. Importantly, these effects were also demonstrated in a clinical setting wherein VSSP monotherapy significantly reduced circulating PMN-MDSCs, and their suppressive function. CONCLUSIONS: Altogether, these data revealed VSSP as a novel regulator of myeloid biology that mitigates MDSCs in cancer patients and reinstates a more normal myeloid phenotype that potentially favors immune activation over immune suppression.

Estrogen Receptor-Beta2 (ERß2)-Mutant p53-FOXM1 Axis: A Novel Driver of Proliferation, Chemoresistance, and Disease Progression in High Grade Serous Ovarian Cancer (HGSOC).

High grade serous ovarian cancer (HGSOC) is the most common and lethal subtype of epithelial ovarian cancer. Prevalence (~96%) of mutant p53 is a hallmark of HGSOC. Estrogen receptor-beta (ERß) has been reported to be another important player in HGSOC, although the pro-versus anti-tumorigenic role of its different isoforms remains unsettled. However, whether there is functional interaction between ERß and mutant p53 in HGSOC is unknown. ERß1 and ERß2 mRNA and protein analysis in HGSOC cell lines demonstrated that ERß2 is the predominant isoform in HGSOC. Specificity of ERß2 antibody was ascertained using cells depleted of ERß2 and ERß1 separately with isoform-specific siRNAs. ERß2-mutant p53 interaction in cell lines was confirmed by co-immunoprecipitation and in situ proximity ligation assay (PLA). Expression levels of ERß2, ERα, p53, and FOXM1 proteins and ERß2-mutant p53 interaction in patient tumors were determined by immunohistochemistry (IHC) and PLA, respectively. ERß2 levels correlate positively with FOXM1 levels and negatively with progression-free survival (PFS) and overall survival (OS). Quantitative chromatin immunoprecipitation (qChIP) and mRNA expression analysis revealed that ERß2 and mutant p53 co-dependently regulated FOXM1 gene transcription. The combination of ERß2-specific siRNA and PRIMA-1MET that converts mutant p53 to wild type conformation increased apoptosis. Our work provides the first evidence for a novel ERß2-mutant p53-FOXM1 axis that can be exploited for new therapeutic strategies against HGSOC.

VSSP abrogates murine ovarian tumor-associated myeloid cell-driven immune suppression and induces M1 polarization in tumor-associated macrophages from ovarian cancer patients.

The ovarian tumor microenvironment (TME) is characterized by the accumulation of immunosuppressive tumor-associated macrophages (TAMs) and granulocytic cells. Very small size particles (VSSP), comprised of the ganglioside NAcGM3 and Neisseria meningitidis derived outer membrane vesicles, is being developed as a nanoparticulated modulator of innate immunity. Prior studies have shown that VSSP enhanced antigen-specific cytotoxic T cell responses and reduced the suppressive phenotype of splenic granulocytic cells in tumor-bearing mice. Here, we hypothesized that intraperitoneal VSSP would modify myeloid cell accumulation and phenotypes in the ovarian TME and abrogate suppressor function of TAMs and tumor-associated granulocytic cells. In the ID8 syngeneic model of epithelial ovarian cancer, VSSP reduced peritoneal TAMs and induced M1-like polarization in TAMs. In addition, VSSP stimulated peritoneal inflammation characterized by increased granulocytes and monocytes, including inflammatory monocytic cells. VSSP treatment resulted in peritoneal TAMs and granulocytic cells being less suppressive of ex vivo stimulated CD8+ T cell responses. VSSP alone and combined with anti-PD-1 modestly but significantly prolonged survival in tumor-bearing mice. In addition, ex vivo treatment with VSSP induced M1-like polarization in TAMs from patients with metastatic ovarian cancer and variably abrogated their suppressor phenotype. VSSP treatment also partially abrogated the induction of suppressor function in healthy donor neutrophils exposed to ascites supernatants from patients with ovarian cancer. Together, these results point to VSSP reprogramming myeloid responses resulting in abrogation of suppressive pathways and raise the potential for administration of VSSP into the TME to enhance anti-tumor immunity.

Loss of MAGEC3 Expression Is Associated with Prognosis in Advanced Ovarian Cancers.

Rare variants in MAGEC3 are associated with BRCA negative, early-onset ovarian cancers. Given this association, we evaluated the impact of MAGEC3 protein expression on prognosis and transcription. We quantified normal and tumor protein expression of MAGEC3 via immunohistochemistry in n = 394 advanced ovarian cancers, assessed the correlation of these values with clinicopathologic and immunological features and modeled survival using univariate and multivariate models. To extend these results, we quantified MAGEC3 protein expression in n = 180 cancers and used matching RNA sequencing data to determine MAGEC3-associated differentially expressed genes and to build an RNA-based model of MAGEC3 protein levels. This model was tested in a third independent cohort of patients from TCGA's OV dataset (n = 282). MAGEC3 protein was sporadically lost in ovarian cancers, with half of the cases falling below the 9.5th percentile of normal tissue expression. Cases with MAGEC3 loss demonstrated better progression-free survival [HR = 0.71, p = 0.004], and analyses performed on predicted protein scores were consistent [HR = 0.57 p = 0.002]. MAGEC3 protein was correlated with CD8 protein expression [Pearson's r = 0.176, p = 0.011], NY-ESO-1 seropositivity, and mRNA expression of tumor antigens at Xq28. Results of gene set enrichment analysis showed that genes associated with MAGEC3 protein expression cluster around G2/M checkpoint (NES = 3.20, FDR < 0.001) and DNA repair (NES = 2.28, FDR < 0.001) hallmark pathways. These results show that MAGEC3 is a prognostic biomarker in ovarian cancer.

Selective therapeutic strategy for p53-deficient cancer by targeting dysregulation in DNA repair.

Breast carcinomas commonly carry mutations in the tumor suppressor p53, although therapeutic efforts to target mutant p53 have previously been unfruitful. Here we report a selective combination therapy strategy for treatment of p53 mutant cancers. Genomic data revealed that p53 mutant cancers exhibit high replication activity and express high levels of the Base-Excision Repair (BER) pathway, whereas experimental testing showed substantial dysregulation in BER. This defect rendered accumulation of DNA damage in p53 mutant cells upon treatment with deoxyuridine analogues. Notably, inhibition of poly (ADP-ribose) polymerase (PARP) greatly enhanced this response, whereas normal cells responded with activation of the p53-p21 axis and cell cycle arrest. Inactivation of either p53 or p21/CDKN1A conferred the p53 mutant phenotype. Preclinical animal studies demonstrated a greater anti-neoplastic efficacy of the drug combination (deoxyuridine analogue and PARP inhibitor) than either drug alone. This work illustrates a selective combination therapy strategy for p53 mutant cancers that will improve survival rates and outcomes for thousands of breast cancer patients.

Mechanisms Driving Neutrophil-Induced T-cell Immunoparalysis in Ovarian Cancer.

T-cell activation and expansion in the tumor microenvironment (TME) are critical for antitumor immunity. Neutrophils in the TME acquire a complement-dependent T-cell suppressor phenotype that is characterized by inhibition of T-cell proliferation and activation through mechanisms distinct from those of myeloid-derived suppressor cells. In this study, we used ascites fluid supernatants (ASC) from patients with ovarian cancer as an authentic component of the TME to evaluate the effects of ASC on neutrophil function and mechanisms for neutrophil-driven immune suppression. ASC prolonged neutrophil life span, decreased neutrophil density, and induced nuclear hypersegmentation. Mass cytometry analysis showed that ASC induced 15 distinct neutrophil clusters. ASC stimulated complement deposition and signaling in neutrophils, resulting in surface mobilization of granule constituents, including NADPH oxidase. NADPH oxidase activation and phosphatidylserine signaling were required for neutrophil suppressor function, although we did not observe a direct role of extracellular reactive oxygen species in inhibiting T-cell proliferation. Postoperative surgical drainage fluid also induced a complement-dependent neutrophil suppressor phenotype, pointing to this effect as a general response to injury. Like circulating lymphocytes, ASC-activated neutrophils caused complement-dependent suppression of tumor-associated lymphocytes. ASC-activated neutrophils adhered to T cells and caused trogocytosis of T-cell membranes. These injury and signaling cues resulted in T-cell immunoparalysis characterized by impaired NFAT translocation, IL2 production, glucose uptake, mitochondrial function, and mTOR activation. Our results demonstrate that complement-dependent priming of neutrophil effector functions in the TME induces a T-cell nonresponsiveness distinct from established checkpoint pathways and identify targets for immunotherapy.See related Spotlight by Cassatella, p. 725.

Patient derived models of bladder cancer enrich the signal of the tumor cell transcriptome facilitating the analysis of the tumor cell compartment.

The evolving paradigm of the molecular classification of bladder cancer requires models that represent the classifications with less heterogeneity. Robust transcriptome based molecular classifications are essential to address tumor heterogeneity. Patient derived models (PDMs) are a powerful preclinical tool to study specific tumor compartments. We tested if the consensus molecular subtype analysis was applicable to PDMs and evaluated the tumor compartment each model represents. PDMs derived from surgical specimens were established as xenografts (PDX), organoids (PDO), and spheroids (PDS). The surgical specimens and PDMs were molecularly characterized by RNA sequencing. PDMs that were established in immune deficient mice or in vitro significantly downregulated transcripts related to the immune and stromal compartments compared to the surgical specimens. However, PDMs upregulate a patient-specific bladder cancer cell signal which allowed for analysis of cancer cell pathways independent of the tumor microenvironment. Based on transcriptomic signatures, PDMs are more similar to their surgical specimen than the model type; indicating that the PDMs retained unique features of the tumor from which the PDM was derived. When comparing models, PDX models were the most similar to the surgical specimen, while PDO and PDS models were most similar to each other. When the consensus molecular subtype classification system was applied to both the surgical samples and the three PDMs, good concordance was found between all samples indicating that this system of classification can be applied to PDO and PDS models. PDMs reduce tumor heterogeneity and allow analysis of tumor cells while maintaining the gene expression profile representative of the original tumor.

USP1 Regulates TAZ Protein Stability Through Ubiquitin Modifications in Breast Cancer.

The Hippo signaling pathway is an evolutionarily conserved pathway that was initially discovered in Drosophila melanogaster and was later found to have mammalian orthologues. The key effector proteins in this pathway, YAP/TAZ, are often dysregulated in cancer, leading to a high degree of cell proliferation, migration, metastasis and cancer stem cell populations. Due to these malignant phenotypes it is important to understand the regulation of YAP/TAZ at the protein level. Using an siRNA library screen of deubiquitinating enzymes (DUBs), we identified ubiquitin specific peptidase 1 (USP1) as a novel TAZ (WWTR1) regulator. We demonstrated that USP1 interacts with TAZ and increases TAZ protein stability. Conversely, loss of function of USP1 reduces TAZ protein levels through increased poly-ubiquitination, causing a decrease in cell proliferation and migration of breast cancer cells. Moreover, we showed a strong positive correlation between USP1 and TAZ in breast cancer patients. Our findings facilitate the attainment of better understanding of the crosstalk between these pathways and may lead to potential therapeutic interventions for breast cancer patients.

Clonality and antigen-specific responses shape the prognostic effects of tumor-infiltrating T cells in ovarian cancer.

CD8+ tumor-infiltrating lymphocytes (TILs) are not all specific for tumor antigens, but can include bystander TILs that are specific for cancer-irrelevant epitopes, and it is unknown whether the T-cell repertoire affects prognosis. To delineate the complexity of anti-tumor T-cell responses, we utilized a computational method for de novo assembly of sequences from CDR3 regions of 369 high-grade serous ovarian cancers from TCGA, and then applied deep TCR-sequencing for analyses of paired tumor and peripheral blood specimens from an independent cohort of 99 ovarian cancer patients. Strongly monoclonal T-cell repertoires were associated with favorable prognosis (PFS, HR = 0.65, 0.50-0.84, p = 0.003; OS, HR = 0.61, 0.44-0.83, p = 0.006) in TCGA cohort. In the validation cohort, we discovered that patients with low T-cell infiltration but low diversity or focused repertoires had clinical outcomes almost indistinguishable from highly-infiltrated tumors (median 21.0 months versus 15.9 months, log-rank p = 0.945). We also found that the degree of divergence of the peripheral repertoire from the TIL repertoire, and the presence of detectable spontaneous anti-tumor immune responses are important determinants of clinical outcome. We conclude that the prognostic significance of TILs in ovarian cancer is dictated by T-cell clonality, degree of overlap with peripheral repertoire, and the presence of detectable spontaneous anti-tumor immune response in the patients. These immunological phenotypes defined by the TCR repertoire may provide useful insights for identifying "TIL-low" ovarian cancer patients that may respond to immunotherapy.

Quantification of Early-Stage Myeloid-Derived Suppressor Cells in Cancer Requires Excluding Basophils.

Myeloid derived suppressor cells (MDSC) are a heterogeneous group of immature cells that accumulate in the peripheral blood and tumor microenvironment and are barriers to cancer therapy. MDSCs serve as prognostic biomarkers and are targets for therapy. On the basis of surface markers, three subsets of MDSCs have been defined in humans: granulocytic, monocytic, and early stage (e-MDSC). The markers attributed to e-MDSCs overlap with those of basophils, which are rare circulating myeloid cells with unrecognized roles in cancer. Thus, we asked whether e-MDSCs in circulation and the tumor microenvironment include basophils. On average, 58% of cells with e-MDSC surface markers in blood and 36% in ascites from patients with ovarian cancer were basophils based on CD123high expression and cytology, whereas cells with immature features were rare. Circulating and ascites basophils did not suppress proliferation of stimulated T cells, a key feature of MDSCs. Increased accumulation of basophils and basogranulin, a marker of basophil degranulation, were observed in ascites compared to serum in patients with newly diagnosed ovarian cancer. Basophils recruited to the tumor microenvironment may exacerbate fluid accumulation by their release of proinflammatory granular constituents that promote vascular leakage. No significant correlation was observed between peripheral basophil counts and survival in patients with ovarian cancer. Our results suggest that studies in which e-MDSCs were defined solely by surface markers should be reevaluated to exclude basophils. Both immaturity and suppression are criteria to define e-MDSCs in future studies.

Inhibition of LSD1 in MDS progenitors restores differentiation of CD141Hi conventional dendritic cells.

The use of immunotherapy to treat patients with myelodysplastic syndromes (MDS) shows promise but is limited by our incomplete understanding of the immunologic milieu. In solid tumors, CD141Hi conventional dendritic cells (CD141Hi cDCs) are necessary for antitumor immunosurveillance and the response to immunotherapy. Here, we found that CD141Hi cDCs are reduced in MDS bone marrow and based on the premise established in solid tumors, we hypothesized that reduced numbers of CD141Hi cDCs are associated with inferior overall survival in MDS patients. We found that MDS patients with reduced numbers of CD141Hi cDCs, but not other DC populations, showed reduced overall survival. To examine the basis for reduction in CD141Hi cDCs, we found fewer numbers of progenitors committed to DC differentiation in the MDS bone marrow and these progenitors expressed lower levels of interferon regulatory factor-8 (IRF8), a master regulator of CD141Hi cDC differentiation. To rescue impaired CD141Hi cDC differentiation, we used pharmacologic inhibition of lysine-specific demethylase 1A (LSD1) to promote CD141Hi cDC differentiation by MDS progenitors. These data reveal a previously unrecognized element of the MDS immunologic milieu. Epigenetic regulation of CD141Hi cDC differentiation offers an intriguing opportunity for intervention and a potential adjunct to immunotherapy for patients with MDS.

Transmission of X-linked Ovarian Cancer: Characterization and Implications.

We recently reported evidence that a strong, BRCA-independent locus on the X-chromosome may contribute to ovarian cancer predisposition in families ascertained from the Familial Ovarian Cancer Registry (Buffalo, NY, USA). While it has been estimated that approximately 20% of all ovarian cancer cases are hereditary, it is possible that a significant proportion of cases previously believed to be sporadic may, in fact, be X-linked. Such X-linked disease has a distinct pattern; it implies that a father will necessarily pass a risk allele to each of his daughters, increasing the prevalence of cancers clustered within a family. X-chromosome inactivation further influences the expression of X-linked alleles and may represent a novel target for screening and therapy. Herein, we review the current literature regarding X-linked ovarian cancer and interpret allele transmission-based models to characterize X-linked ovarian cancer and develop a framework for clinical and epidemiological familial ascertainment to inform the design of future studies.

Alternative polyadenylation drives oncogenic gene expression in pancreatic ductal adenocarcinoma.

Alternative polyadenylation (APA) is a gene regulatory process that dictates mRNA 3'-UTR length, resulting in changes in mRNA stability and localization. APA is frequently disrupted in cancer and promotes tumorigenesis through altered expression of oncogenes and tumor suppressors. Pan-cancer analyses have revealed common APA events across the tumor landscape; however, little is known about tumor type-specific alterations that may uncover novel events and vulnerabilities. Here, we integrate RNA-sequencing data from the Genotype-Tissue Expression (GTEx) project and The Cancer Genome Atlas (TCGA) to comprehensively analyze APA events in 148 pancreatic ductal adenocarcinomas (PDACs). We report widespread, recurrent, and functionally relevant 3'-UTR alterations associated with gene expression changes of known and newly identified PDAC growth-promoting genes and experimentally validate the effects of these APA events on protein expression. We find enrichment for APA events in genes associated with known PDAC pathways, loss of tumor-suppressive miRNA binding sites, and increased heterogeneity in 3'-UTR forms of metabolic genes. Survival analyses reveal a subset of 3'-UTR alterations that independently characterize a poor prognostic cohort among PDAC patients. Finally, we identify and validate the casein kinase CSNK1A1 (also known as CK1alpha or CK1a) as an APA-regulated therapeutic target in PDAC. Knockdown or pharmacological inhibition of CSNK1A1 attenuates PDAC cell proliferation and clonogenic growth. Our single-cancer analysis reveals APA as an underappreciated driver of protumorigenic gene expression in PDAC via the loss of miRNA regulation.

Prostate tumor-derived GDF11 accelerates androgen deprivation therapy-induced sarcopenia.

Most prostate cancers depend on androgens for growth, and therefore, the mainstay treatment for advanced, recurrent, or metastatic prostate cancer is androgen deprivation therapy (ADT). A prominent side effect in patients receiving ADT is an obese frailty syndrome that includes fat gain and sarcopenia, defined as the loss of muscle function accompanied by reduced muscle mass or quality. Mice bearing Pten-deficient prostate cancers were examined to gain mechanistic insight into ADT-induced sarcopenic obesity. Castration induced fat gain as well as skeletal muscle mass and strength loss. Catabolic TGF-ß family myokine protein levels were increased immediately prior to strength loss, and pan-myokine blockade using a soluble receptor (ActRIIB-Fc) completely reversed the castration-induced sarcopenia. The onset of castration-induced strength and muscle mass loss, as well as the increase in catabolic TGF-ß family myokine protein levels, were coordinately accelerated in tumor-bearing mice relative to tumor-free mice. Notably, growth differentiation factor 11 (GDF11) increased in muscle after castration only in tumor-bearing mice, but not in tumor­free mice. An early surge of GDF11 in prostate tumor tissue and in the circulation suggests that endocrine GDF11 signaling from tumor to muscle is a major driver of the accelerated ADT-induced sarcopenic phenotype. In tumor-bearing mice, GDF11 blockade largely prevented castration-induced strength loss but did not preserve muscle mass, which confirms a primary role for GDF11 in muscle function and suggests an additional role for the other catabolic myokines.

Whole-exome sequencing of ovarian cancer families uncovers putative predisposition genes.

Despite the identification of several ovarian cancer (OC) predisposition genes, a large proportion of familial OC risk remains unexplained. We adopted a two-stage design to identify new OC predisposition genes. We first carried out a large germline whole-exome sequencing study on 158 patients from 140 families with significant OC history, but without evidence of genetic predisposition due to BRCA1/2. We then evaluated the potential candidate genes in a large case-control association study involving 381 OC cases in the Cancer Genome Atlas project and 27,173 population controls from the Exome Aggregation Consortium. Two new putative OC risk genes were identified, namely, ANKRD11, a putative tumor suppressor, and POLE, an enzyme involved in DNA repair and replication. These two genes likely confer moderate OC risk. We performed in vitro experiments and showed an ANKRD11 mutation identified in our patients markedly lowered the protein expression by compromising protein stability. Upon future validation and functional characterization, these genes may shed light on cancer etiology along with improving ascertainment power and preventive care of individuals at high risk of OC.