XPC Protects against Carcinogen-Induced Histologic Progression to Lung Squamous Cell Carcinoma by Reduced Basal Epithelial Cell Proliferation.

Lung squamous cell carcinoma (LUSC) is the second leading cause of lung cancer. Although characterized by high DNA mutational burdens and genomic complexity, the role of DNA repair in LUSC development is poorly understood. We sought to better understand the role of the DNA repair protein Xeroderma Pigmentosum Group C (XPC) in LUSC development. XPC knock-out (KO), heterozygous, and wild-type (WT) mice were exposed topically to N-nitroso-tris-chloroethylurea (NTCU), and lungs were evaluated for histology and pre-malignant progression in a blinded fashion at various time-points from 8-24 weeks. High-grade dysplasia and LUSC were increased in XPC KO compared with XPC WT NTCU mice (56% vs. 34%), associated with a higher mean LUSC lung involvement (p < 0.05). N-acetylcysteine pre-treatment decreased bronchoalveolar inflammation but did not prevent LUSC development. Proliferation, measured as %Ki67+ cells, increased with NTCU treatment, in high-grade dysplasia and LUSC, and in XPC deficiency (p < 0.01, ANOVA). Finally, pre-LUSC dysplasia developed earlier and progressed to higher histologic classification sooner in XPC KO compared with WT mice. Overall, this supports the protective role of XPC in squamous dysplasia progression to LUSC. Mouse models of early LUSC development are limited; this may provide a valuable model to study mechanisms of LUSC development and progression.

Combined CDK4/6 and ERK1/2 Inhibition Enhances Antitumor Activity in NF1-Associated Plexiform Neurofibroma.

PURPOSE: Plexiform neurofibromas (PNF) are peripheral nerve sheath tumors that cause significant morbidity in persons with neurofibromatosis type 1 (NF1), yet treatment options remain limited. To identify novel therapeutic targets for PNF, we applied an integrated multi-omic approach to quantitatively profile kinome enrichment in a mouse model that has predicted therapeutic responses in clinical trials for NF1-associated PNF with high fidelity. EXPERIMENTAL DESIGN: Utilizing RNA sequencing combined with chemical proteomic profiling of the functionally enriched kinome using multiplexed inhibitor beads coupled with mass spectrometry, we identified molecular signatures predictive of response to CDK4/6 and RAS/MAPK pathway inhibition in PNF. Informed by these results, we evaluated the efficacy of the CDK4/6 inhibitor, abemaciclib, and the ERK1/2 inhibitor, LY3214996, alone and in combination in reducing PNF tumor burden in Nf1flox/flox;PostnCre mice. RESULTS: Converging signatures of CDK4/6 and RAS/MAPK pathway activation were identified within the transcriptome and kinome that were conserved in both murine and human PNF. We observed robust additivity of the CDK4/6 inhibitor, abemaciclib, in combination with the ERK1/2 inhibitor, LY3214996, in murine and human NF1(Nf1) mutant Schwann cells. Consistent with these findings, the combination of abemaciclib (CDK4/6i) and LY3214996 (ERK1/2i) synergized to suppress molecular signatures of MAPK activation and exhibited enhanced antitumor activity in Nf1flox/flox;PostnCre mice in vivo. CONCLUSIONS: These findings provide rationale for the clinical translation of CDK4/6 inhibitors alone and in combination with therapies targeting the RAS/MAPK pathway for the treatment of PNF and other peripheral nerve sheath tumors in persons with NF1.

Obesity-induced inflammation exacerbates clonal hematopoiesis.

Characterized by the accumulation of somatic mutations in blood cell lineages, clonal hematopoiesis of indeterminate potential (CHIP) is frequent in aging and involves the expansion of mutated hematopoietic stem and progenitor cells (HSC/Ps) that leads to an increased risk of hematologic malignancy. However, the risk factors that contribute to CHIP-associated clonal hematopoiesis (CH) are poorly understood. Obesity induces a proinflammatory state and fatty bone marrow (FBM), which may influence CHIP-associated pathologies. We analyzed exome sequencing and clinical data for 47,466 individuals with validated CHIP in the UK Biobank. CHIP was present in 5.8% of the study population and was associated with a significant increase in the waist-to-hip ratio (WHR). Mouse models of obesity and CHIP driven by heterozygosity of Tet2, Dnmt3a, Asxl1, and Jak2 resulted in exacerbated expansion of mutant HSC/Ps due in part to excessive inflammation. Our results show that obesity is highly associated with CHIP and that a proinflammatory state could potentiate the progression of CHIP to more significant hematologic neoplasia. The calcium channel blockers nifedipine and SKF-96365, either alone or in combination with metformin, MCC950, or anakinra (IL-1 receptor antagonist), suppressed the growth of mutant CHIP cells and partially restored normal hematopoiesis. Targeting CHIP-mutant cells with these drugs could be a potential therapeutic approach to treat CH and its associated abnormalities in individuals with obesity.

Use of multimodality imaging, histology, and treatment feasibility to characterize a transgenic Rag2-null rat model of glioblastoma.

Many drugs that show potential in animal models of glioblastoma (GBM) fail to translate to the clinic, contributing to a paucity of new therapeutic options. In addition, animal model development often includes histologic assessment, but multiparametric/multimodality imaging is rarely included despite increasing utilization in patient cancer management. This study developed an intracranial recurrent, drug-resistant, human-derived glioblastoma tumor in Sprague-Dawley Rag2-Rag2 tm1Hera knockout rat and was characterized both histologically and using multiparametric/multimodality neuroimaging. Hybrid 18F-fluoroethyltyrosine positron emission tomography and magnetic resonance imaging, including chemical exchange saturation transfer (18F-FET PET/CEST MRI), was performed for full tumor viability determination and characterization. Histological analysis demonstrated human-like GBM features of the intracranially implanted tumor, with rapid tumor cell proliferation (Ki67 positivity: 30.5 ± 7.8%) and neovascular heterogeneity (von Willebrand factor VIII:1.8 to 5.0% positivity). Early serial MRI followed by simultaneous 18F-FET PET/CEST MRI demonstrated consistent, predictable tumor growth, with exponential tumor growth most evident between days 35 and 49 post-implantation. In a second, larger cohort of rats, 18F-FET PET/CEST MRI was performed in mature tumors (day 49 post-implantation) for biomarker determination, followed by evaluation of single and combination therapy as part of the model development and validation. The mean percentage of the injected dose per mL of 18F-FET PET correlated with the mean %CEST (r = 0.67, P < 0.05), but there was also a qualitative difference in hot spot location within the tumor, indicating complementary information regarding the tumor cell demand for amino acids and tumor intracellular mobile phase protein levels. Finally, the use of this glioblastoma animal model for therapy assessment was validated by its increased overall survival after treatment with combination therapy (temozolomide and idasanutlin) (P < 0.001). Our findings hold promise for a more accurate tumor viability determination and novel therapy assessment in vivo in a recently developed, reproducible, intracranial, PDX GBM.

Metabolic Links to Socioeconomic Stresses Uniquely Affecting Ancestry in Normal Breast Tissue at Risk for Breast Cancer.

A primary difference between black women (BW) and white women (WW) diagnosed with breast cancer is aggressiveness of the tumor. Black women have higher mortalities with similar incidence of breast cancer compared to other race/ethnicities, and they are diagnosed at a younger age with more advanced tumors with double the rate of lethal, triple negative breast cancers. One hypothesis is that chronic social and economic stressors result in ancestry-dependent molecular responses that create a tumor permissive tissue microenvironment in normal breast tissue. Altered regulation of N-glycosylation of proteins, a glucose metabolism-linked post-translational modification attached to an asparagine (N) residue, has been associated with two strong independent risk factors for breast cancer: increased breast density and body mass index (BMI). Interestingly, high body mass index (BMI) levels have been reported to associate with increases of cancer-associated N-glycan signatures. In this study, we used matrix assisted laser desorption/ionization (MALDI) imaging mass spectrometry (IMS) to investigate molecular pattern changes of N-glycosylation in ancestry defined normal breast tissue from BW and WW with significant 5-year risk of breast cancer by Gail score. N-glycosylation was tested against social stressors including marital status, single, education, economic status (income), personal reproductive history, the risk factors BMI and age. Normal breast tissue microarrays from the Susan G. Komen tissue bank (BW=43; WW= 43) were used to evaluate glycosylation against socioeconomic stress and risk factors. One specific N-glycan (2158 m/z) appeared dependent on ancestry with high sensitivity and specificity (AUC 0.77, Brown/Wilson p-value<0.0001). Application of a linear regression model with ancestry as group variable and socioeconomic covariates as predictors identified a specific N-glycan signature associated with different socioeconomic stresses. For WW, household income was strongly associated to certain N-glycans, while for BW, marital status (married and single) was strongly associated with the same N-glycan signature. Current work focuses on understanding if combined N-glycan biosignatures can further help understand normal breast tissue at risk. This study lays the foundation for understanding the complexities linking socioeconomic stresses and molecular factors to their role in ancestry dependent breast cancer risk.

FAM83A is a potential biomarker for breast cancer initiation.

BACKGROUND: Family with sequence similarity 83 member A (FAM83A) presents oncogenic properties in several cancers including breast cancer. Recently, we reported FAM83A overexpression in normal breast tissues from women at high risk of breast cancer. We now hypothesize that FAM83A is a key factor in breast cancer initiation. METHODS: Immunohistochemical staining was used to evaluate FAM83A protein levels in both a normal breast tissue microarray (TMA, N = 411) and a breast tumor TMA (N = 349). EGFR staining and its correlation with FAM83A expression were also assessed. Lentivirus-mediated manipulation of FAM83A expression in primary and hTERT-immortalized breast epithelial cells was employed. Biological and molecular alterations upon FAM83A overexpression/downregulation and FAM83A's interaction partners were investigated. RESULTS: TMA analysis revealed a 1.5-fold increase in FAM83A expression level in breast cancer cases as compared with normal breast tissues (p < 0.0001). FAM83A protein expression was directly correlated with EGFR level in both normal and breast cancer tissues. In in vitro assays, exogenous expression of FAM83A in either primary or immortalized breast epithelial cells promoted cell viability and proliferation. Additionally, Ingenuity Pathway Analysis (IPA) revealed that FAM83A overexpression in primary cells affected the expression of genes involved in cellular morphology and metabolism. Mass spectrometry analysis identified DDX3X and LAMB3 as potential FAM83A interaction partners in primary cells, while we detected FAM83A interaction with cytoskeleton reorganization factors, including LIMA1, MYH10, PLEC, MYL6 in the immortalized cells. CONCLUSIONS: This study shows that FAM83A promotes metabolic activation in primary breast epithelial cells and cell proliferation in both primary and immortalized cells. These findings support its role in early breast oncogenesis.

Aberrant epigenetic and transcriptional events associated with breast cancer risk.

BACKGROUND: Genome-wide association studies have identified several breast cancer susceptibility loci. However, biomarkers for risk assessment are still missing. Here, we investigated cancer-related molecular changes detected in tissues from women at high risk for breast cancer prior to disease manifestation. Disease-free breast tissue cores donated by healthy women (N = 146, median age = 39 years) were processed for both methylome (MethylCap) and transcriptome (Illumina's HiSeq4000) sequencing. Analysis of tissue microarray and primary breast epithelial cells was used to confirm gene expression dysregulation. RESULTS: Transcriptomic analysis identified 69 differentially expressed genes between women at high and those at average risk of breast cancer (Tyrer-Cuzick model) at FDR < 0.05 and fold change ≥ 2. Majority of the identified genes were involved in DNA damage checkpoint, cell cycle, and cell adhesion. Two genes, FAM83A and NEK2, were overexpressed in tissue sections (FDR < 0.01) and primary epithelial cells (p < 0.05) from high-risk breasts. Moreover, 1698 DNA methylation changes were identified in high-risk breast tissues (FDR < 0.05), partially overlapped with cancer-related signatures, and correlated with transcriptional changes (p < 0.05, r ≤ 0.5). Finally, among the participants, 35 women donated breast biopsies at two time points, and age-related molecular alterations enhanced in high-risk subjects were identified. CONCLUSIONS: Normal breast tissue from women at high risk of breast cancer bears molecular aberrations that may contribute to breast cancer susceptibility. This study is the first molecular characterization of the true normal breast tissues, and provides an opportunity to investigate molecular markers of breast cancer risk, which may lead to new preventive approaches.

Exposure to perfluorooctanoic acid leads to promotion of pancreatic cancer.

Pancreatic cancer is the fourth leading cause of cancer deaths in the United States. Perfluorooctanoic acid (PFOA), a persistent environmental pollutant, has been shown to induce pancreatic acinar cell tumors in rats. Human epidemiologic studies have linked PFOA exposure to adverse chronic health effects including several types of cancer. Previously, we demonstrated that PFOA induces oxidative stress and focal ductal hyperplasia in the mouse pancreas. Here, we evaluated whether PFOA promotes pancreatic cancer using the LSL-KRasG12D;Pdx-1 Cre (KC) mouse model of pancreatic cancer. KC mice were exposed to 5 ppm PFOA in drinking water starting at 8 weeks of age and analyzed at 6 and 9 months of age. At the 6-month time point, PFOA exposure increased pancreatic intraepithelial neoplasia (PanIN) area by 58%, accompanied by a 2-fold increase in lesion number. Although PanIN area increased at 9 months, relative to 6 months, no treatment effect was observed. Collagen deposition was enhanced by PFOA at both the 6- and 9-month time points. PFOA also induced oxidative stress in the pancreas evidenced by elevated antioxidant activity of superoxide dismutase (Sod), catalase and thioredoxin reductase, and a ~3-fold increase in Sod1 mRNA and protein levels at 6 months. Although antioxidant activity was not enhanced by PFOA exposure at the 9-month time point, increased pancreatic oxidative damage was observed. Collectively, these results show that PFOA elicited temporal increases in PanIN lesion area and desmoplasia concomitant with the induction of oxidative stress, demonstrating that it functions to promote pancreatic cancer progression.

Integrative Multi-OMICs Identifies Therapeutic Response Biomarkers and Confirms Fidelity of Clinically Annotated, Serially Passaged Patient-Derived Xenografts Established from Primary and Metastatic Pediatric and AYA Solid Tumors.

Establishment of clinically annotated, molecularly characterized, patient-derived xenografts (PDXs) from treatment-naïve and pretreated patients provides a platform to test precision genomics-guided therapies. An integrated multi-OMICS pipeline was developed to identify cancer-associated pathways and evaluate stability of molecular signatures in a panel of pediatric and AYA PDXs following serial passaging in mice. Original solid tumor samples and their corresponding PDXs were evaluated by whole-genome sequencing, RNA-seq, immunoblotting, pathway enrichment analyses, and the drug−gene interaction database to identify as well as cross-validate actionable targets in patients with sarcomas or Wilms tumors. While some divergence between original tumor and the respective PDX was evident, majority of alterations were not functionally impactful, and oncogenic pathway activation was maintained following serial passaging. CDK4/6 and BETs were prioritized as biomarkers of therapeutic response in osteosarcoma PDXs with pertinent molecular signatures. Inhibition of CDK4/6 or BETs decreased osteosarcoma PDX growth (two-way ANOVA, p < 0.05) confirming mechanistic involvement in growth. Linking patient treatment history with molecular and efficacy data in PDX will provide a strong rationale for targeted therapy and improve our understanding of which therapy is most beneficial in patients at diagnosis and in those already exposed to therapy.

Pharmacological inhibition of Carbonic Anhydrase IX and XII to enhance targeting of acute myeloid leukaemia cells under hypoxic conditions.

Acute myeloid leukaemia (AML) is an aggressive form of blood cancer that carries a dismal prognosis. Several studies suggest that the poor outcome is due to a small fraction of leukaemic cells that elude treatment and survive in specialised, oxygen (O2 )-deprived niches of the bone marrow. Although several AML drug targets such as FLT3, IDH1/2 and CD33 have been established in recent years, survival rates remain unsatisfactory, which indicates that other, yet unrecognized, mechanisms influence the ability of AML cells to escape cell death and to proliferate in hypoxic environments. Our data illustrates that Carbonic Anhydrases IX and XII (CA IX/XII) are critical for leukaemic cell survival in the O2 -deprived milieu. CA IX and XII function as transmembrane proteins that mediate intracellular pH under low O2 conditions. Because maintaining a neutral pH represents a key survival mechanism for tumour cells in O2 -deprived settings, we sought to elucidate the role of dual CA IX/XII inhibition as a novel strategy to eliminate AML cells under hypoxic conditions. Our findings demonstrate that the dual CA IX/XII inhibitor FC531 may prove to be of value as an adjunct to chemotherapy for the treatment of AML.

Folate-targeted intraoperative fluorescence, OTL38, in robotic-assisted laparoscopic partial nephrectomy.

OBJECTIVE: To investigate the safety and efficacy of OTL38, a folate-targeted, intraoperative fluorescence agent, in patients undergoing robotic-assisted laparoscopic partial nephrectomy. METHODS: Patients with proven or suspected localized renal cell carcinoma at a single academic institution were selected from 2016 to 2018. Patients received one dose of OTL38 at 0.025 mg/kg prior to robotic-assisted laparoscopic partial nephrectomy. The da Vinci Fluorescence Imaging Vision System was used to identify the tumor and inspect for residual disease after resection. Immunohistochemistry was performed to quantify folate receptor alpha in both the tumor and surrounding normal parenchyma. Patient follow-up was 1 month. Outcome data included descriptive statistics of the patient cohort and surgeon and pathologist surveys. RESULTS: Ten cases were performed. Mean patient age was 62.9 years (range = 50-70). Mean tumor size was 2.45 cm. Pathologic tumor stages ranged from T1a-T3a. Histologic tumor types included clear cell, chromophobe, type 1 papillary renal cell carcinoma and oncocytoma. The tumors did not fluoresce, while the surrounding normal parenchyma did show fluorescence. No adverse reactions were seen. Staining for folate receptor alpha was localized to the proximal renal tubules. Average staining in normal surrounding renal parenchyma was significantly greater than staining observed in tumor tissue (0.2086 vs 0.0467; p = 0.002). The mean difference in staining between tumor tissue and surrounding normal renal parenchyma was 0.1619 (95% CI = 0.0796-0.2442). CONCLUSIONS: Based on our initial experience, OTL38 shows potential as a safe, effective and easy to use tool to improve visualization and resection of renal tumors.

Atractylenolide I enhances responsiveness to immune checkpoint blockade therapy by activating tumor antigen presentation.

One of the primary mechanisms of tumor cell immune evasion is the loss of antigenicity, which arises due to lack of immunogenic tumor antigens as well as dysregulation of the antigen processing machinery. In a screen for small-molecule compounds from herbal medicine that potentiate T cell-mediated cytotoxicity, we identified atractylenolide I (ATT-I), which substantially promotes tumor antigen presentation of both human and mouse colorectal cancer (CRC) cells and thereby enhances the cytotoxic response of CD8+ T cells. Cellular thermal shift assay (CETSA) with multiplexed quantitative mass spectrometry identified the proteasome 26S subunit non-ATPase 4 (PSMD4), an essential component of the immunoproteasome complex, as a primary target protein of ATT-I. Binding of ATT-I with PSMD4 augments the antigen-processing activity of immunoproteasome, leading to enhanced MHC-I-mediated antigen presentation on cancer cells. In syngeneic mouse CRC models and human patient-derived CRC organoid models, ATT-I treatment promotes the cytotoxicity of CD8+ T cells and thus profoundly enhances the efficacy of immune checkpoint blockade therapy. Collectively, we show here that targeting the function of immunoproteasome with ATT-I promotes tumor antigen presentation and empowers T cell cytotoxicity, thus elevating the tumor response to immunotherapy.

MAL2 drives immune evasion in breast cancer by suppressing tumor antigen presentation.

Immune evasion is a pivotal event in tumor progression. To eliminate human cancer cells, current immune checkpoint therapy is set to boost CD8+ T cell-mediated cytotoxicity. However, this action is eventually dependent on the efficient recognition of tumor-specific antigens via T cell receptors. One primary mechanism by which tumor cells evade immune surveillance is to downregulate their antigen presentation. Little progress has been made toward harnessing potential therapeutic targets for enhancing antigen presentation on the tumor cell. Here, we identified MAL2 as a key player that determines the turnover of the antigen-loaded MHC-I complex and reduces the antigen presentation on tumor cells. MAL2 promotes the endocytosis of tumor antigens via direct interaction with the MHC-I complex and endosome-associated RAB proteins. In preclinical models, depletion of MAL2 in breast tumor cells profoundly enhanced the cytotoxicity of tumor-infiltrating CD8+ T cells and suppressed breast tumor growth, suggesting that MAL2 is a potential therapeutic target for breast cancer immunotherapy.

A phase 1 study of combined guadecitabine and cisplatin in platinum refractory germ cell cancer.

PURPOSE: Germ cell tumors (GCTs) are cured with therapy based on cisplatin, although a clinically significant number of patients are refractory and die of progressive disease. Based on preclinical studies indicating that refractory testicular GCTs are hypersensitive to hypomethylating agents (HMAs), we conducted a phase I trial combining the next-generation HMA guadecitabine (SGI-110) with cisplatin in recurrent, cisplatin-resistant GCT patients. METHODS: Patients with metastatic GCTs were treated for five consecutive days with guadecitabine followed by cisplatin on day 8, for a 28-day cycle for up to six cycles. The primary endpoint was safety and toxicity including dose-limiting toxicity (DLT) and maximum tolerated dose (MTD). RESULTS: The number of patients enrolled was 14. The majority of patients were heavily pretreated. MTD was determined to be 30 mg/m2 guadecitabine followed by 100 mg/m2 cisplatin. The major DLTs were neutropenia and thrombocytopenia. Three patients had partial responses by RECIST criteria, two of these patients, including one with primary mediastinal disease, completed the study and qualified as complete responses by serum tumor marker criteria with sustained remissions of 5 and 13 months and survival of 16 and 26 months, respectively. The overall response rate was 23%. Three patients also had stable disease indicating a clinical benefit rate of 46%. CONCLUSIONS: The combination of guadecitabine and cisplatin was tolerable and demonstrated activity in patients with platinum refractory germ cell cancer.

Regulation of cellular sterol homeostasis by the oxygen responsive noncoding RNA lincNORS.

We hereby provide the initial portrait of lincNORS, a spliced lincRNA generated by the MIR193BHG locus, entirely distinct from the previously described miR-193b-365a tandem. While inducible by low O2 in a variety of cells and associated with hypoxia in vivo, our studies show that lincNORS is subject to multiple regulatory inputs, including estrogen signals. Biochemically, this lincRNA fine-tunes cellular sterol/steroid biosynthesis by repressing the expression of multiple pathway components. Mechanistically, the function of lincNORS requires the presence of RALY, an RNA-binding protein recently found to be implicated in cholesterol homeostasis. We also noticed the proximity between this locus and naturally occurring genetic variations highly significant for sterol/steroid-related phenotypes, in particular the age of sexual maturation. An integrative analysis of these variants provided a more formal link between these phenotypes and lincNORS, further strengthening the case for its biological relevance.

Immune Reconstitution and Thymic Involution in the Acute and Delayed Hematopoietic Radiation Syndromes.

Lymphoid lineage recovery and involution after exposure to potentially lethal doses of ionizing radiation have not been well defined, especially the long-term effects in aged survivors and with regard to male/female differences. To examine these questions, male and female C57BL/6 mice were exposed to lethal radiation at 12 wk of age in a model of the Hematopoietic-Acute Radiation Syndrome, and bone marrow, thymus, spleen, and peripheral blood examined up to 24 mo of age for the lymphopoietic delayed effects of acute radiation exposure. Aged mice showed myeloid skewing and incomplete lymphocyte recovery in all lymphoid tissues. Spleen and peripheral blood both exhibited a monophasic recovery pattern, while thymus demonstrated a biphasic pattern. Naïve T cells in blood and spleen and all subsets of thymocytes were decreased in aged irradiated mice compared to age-matched non-irradiated controls. Of interest, irradiated males experienced significantly improved reconstitution of thymocyte subsets and peripheral blood elements compared to females. Bone marrow from aged irradiated survivors was significantly deficient in the primitive lymphoid-primed multipotent progenitors and common lymphoid progenitors, which were only 8-10% of levels in aged-matched non-irradiated controls. Taken together, these analyses define significant age- and sex-related deficiencies at all levels of lymphopoiesis throughout the lifespan of survivors of the Hematopoietic-Acute Radiation Syndrome and may provide a murine model suitable for assessing the efficacy of potential medical countermeasures and therapeutic strategies to alleviate the severe immune suppression that occurs after radiation exposure.

EZH2-Mediated Downregulation of the Tumor Suppressor DAB2IP Maintains Ovarian Cancer Stem Cells.

The majority of women diagnosed with epithelial ovarian cancer eventually develop recurrence, which rapidly evolves into chemoresistant disease. Persistence of ovarian cancer stem cells (OCSC) at the end of therapy may be responsible for emergence of resistant tumors. In this study, we demonstrate that in OCSC, the tumor suppressor disabled homolog 2-interacting protein (DAB2IP) is silenced by EZH2-mediated H3K27 trimethylation of the DAB2IP promoter. CRISPR/Cas9-mediated deletion of DAB2IP in epithelial ovarian cancer cell lines upregulated expression of stemness-related genes and induced conversion of non-CSC to CSC, while enforced expression of DAB2IP suppressed CSC properties. Transcriptomic analysis showed that overexpression of DAB2IP in ovarian cancer significantly altered stemness-associated genes and bioinformatic analysis revealed WNT signaling as a dominant pathway mediating the CSC inhibitory effect of DAB2IP. Specifically, DAB2IP inhibited WNT signaling via downregulation of WNT5B, an important stemness inducer. Reverse phase protein array further demonstrated activation of noncanonical WNT signaling via C-JUN as a downstream target of WNT5B, which was blocked by inhibiting RAC1, a prominent regulator of C-JUN activation. Coadministration of EZH2 inhibitor GSK126 and RAC1 inhibitor NSC23766 suppressed OCSC survival in vitro and inhibited tumor growth and increased platinum sensitivity in vivo. Overall, these data establish that DAB2IP suppresses the cancer stem cell phenotype via inhibition of WNT5B-induced activation of C-JUN and can be epigenetically silenced by EZH2 in OCSC. Targeting the EZH2/DAB2IP/C-JUN axis therefore presents a promising strategy to prevent ovarian cancer recurrence and has potential for clinical translation. SIGNIFICANCE: These findings show that combining an epigenetic therapy with a noncanonical WNT signaling pathway inhibitor has the potential to eradicate ovarian cancer stem cells and to prevent ovarian cancer recurrence.

ST2 as checkpoint target for colorectal cancer immunotherapy.

Immune checkpoint blockade immunotherapy delivers promising clinical results in colorectal cancer (CRC). However, only a fraction of cancer patients develop durable responses. The tumor microenvironment (TME) negatively impacts tumor immunity and subsequently clinical outcomes. Therefore, there is a need to identify other checkpoint targets associated with the TME. Early-onset factors secreted by stromal cells as well as tumor cells often help recruit immune cells to the TME, among which are alarmins such as IL-33. The only known receptor for IL-33 is stimulation 2 (ST2). Here we demonstrated that high ST2 expression is associated with poor survival and is correlated with low CD8+ T cell cytotoxicity in CRC patients. ST2 is particularly expressed in tumor-associated macrophages (TAMs). In preclinical models of CRC, we demonstrated that ST2-expressing TAMs (ST2+ TAMs) were recruited into the tumor via CXCR3 expression and exacerbated the immunosuppressive TME; and that combination of ST2 depletion using ST2-KO mice with anti-programmed death 1 treatment resulted in profound growth inhibition of CRC. Finally, using the IL-33trap fusion protein, we suppressed CRC tumor growth and decreased tumor-infiltrating ST2+ TAMs. Together, our findings suggest that ST2 could serve as a potential checkpoint target for CRC immunotherapy.

Breast Heterogeneity: Obstacles to Developing Universal Biomarkers of Breast Cancer Initiation and Progression.

BACKGROUND: Predicting outcomes and response to therapy through biomarkers is a major challenge in cancer research. In previous studies, we suggested that inappropriate "normal" tissue samples used for comparison with tumors, inter-individual heterogeneity in gene expression, and genetic ancestry all influence biomarker expression in tumors. The aim of this study was to investigate these factors in breast cancer using breast tissues from healthy women and normal tissue adjacent to tumor (NAT) with matrix metalloproteinase 7 (MMP7) as a candidate biomarker. STUDY DESIGN: RNA sequencing was performed on primary luminal progenitor cells from healthy breast, NATs, and tumors to identify transcriptomes enriched in NATs and breast cancer. Expression of select genes was validated via quantitative reverse transcription polymerase chain reaction of RNA and via immunohistochemistry of a tissue microarray of normal, NAT, and tumor samples of different genetic ancestry. RESULTS: Twenty-six genes were significantly overexpressed in NATs and tumors compared with healthy controls at messenger RNA level and formed a para-inflammatory network. MMP7 had the greatest expression in tumor cells, with upregulation confirmed by quantitative reverse transcription polymerase chain reaction. Tumor-enriched but not NAT-enriched expression of MMP7 compared with healthy controls was reproduced at protein levels. When stratified by genetic ancestry, tumor-specific increase of MMP7 reached statistical significance in women of European ancestry. CONCLUSIONS: Transcriptome differences across healthy, NAT, and tumor tissue in breast cancer demonstrate an active para-inflammatory network in NATs and indicate unsuitability of NATs as "normal controls" in biomarker discovery. The discordance between transcriptomic and proteomic MMP7 expression in NATs and the influence of genetic ancestry on its protein expression highlight the complexity in developing universally acceptable biomarkers of breast cancer and the importance of genetic ancestry in biomarker development.