ABSTRACT
Photothermal therapy (PTT) refers to the use of plasmonic nanoparticles to convert electromagnetic radiation in the near infrared region to heat and kill tumor cells. Continuous wave lasers have been used clinically to induce PTT, but the treatment is associated with heat-induced tissue damage that limits usability. Here, the engineering and validation of a novel long-pulsed laser device able to induce selective and localized mild hyperthermia in tumors while reducing the heat affected zone and unwanted damage to surrounding tissue are reported. Long-pulsed PTT induces acute necrotic cell death in heat affected areas and the release of tumor associated antigens. This antigen release triggers maturation and stimulation of CD80/CD86 in dendritic cells in vivo that primes a cytotoxic T cell response. Accordingly, long-pulsed PTT enhances the therapeutic effects of immune checkpoint inhibition and increases survival of mice with bladder cancer. Combined, the data promote long-pulsed PTT as a safe and effective strategy for enhancing therapeutic responses to immune checkpoint inhibitors while minimizing unwanted tissue damage.
Subject(s)
Immunotherapy , Photothermal Therapy , Immunotherapy/methods , Animals , Photothermal Therapy/methods , Mice , Neoplasms/therapy , Humans , Cell Line, TumorABSTRACT
Malaria infected erythrocytes utilize the parasite protein VAR2CSA to bind to a unique presentation of chondroitin sulfate (CS) for their placenta specific tropism. Interestingly, many cancers express a similar form of CS, thereby termed oncofetal CS (ofCS). The distinctive tropism of malaria infected erythrocytes and the identification of oncofetal CS, therefore, represent potentially potent tools for cancer targeting. Here we describe an intriguing drug delivery platform that effectively mimics infected erythrocytes and their specificity for ofCS. We used a lipid catcher-tag conjugation system for the functionalization of erythrocyte membrane-coated drug carriers with recombinant VAR2CSA (rVAR2). We show that these malaria mimicking erythrocyte nanoparticles (MMENPs) loaded with docetaxel (DTX) specifically target and kill melanoma cells in vitro. We further demonstrate effective targeting and therapeutic efficacy in a xenografted melanoma model. These data thus provide a proof of concept for the use of a malaria biomimetic for tumor targeted drug delivery. Given the broad presentation of ofCS found across various types of malignancies, this biomimetic may therefore show potential as a broadly targeted cancer therapy against multiple tumor indications.
Subject(s)
Malaria, Falciparum , Malaria , Melanoma , Humans , Antigens, Protozoan/metabolism , Biomimetics , Chondroitin Sulfates/metabolism , Erythrocytes/metabolism , Malaria, Falciparum/metabolism , Plasmodium falciparumABSTRACT
PURPOSE: Histone deacetylase (HDAC) inhibition has been shown to induce pharmacologic "BRCAness" in cancer cells with proficient DNA repair activity. This provides a rationale for exploring combination treatments with HDAC and PARP inhibition in cancer types that are insensitive to single-agent PARP inhibitors (PARPi). Here, we report the concept and characterization of a novel bifunctional PARPi (kt-3283) with dual activity toward PARP1/2 and HDAC enzymes in Ewing sarcoma cells. EXPERIMENTAL DESIGN: Inhibition of PARP1/2 and HDAC was measured using PARP1/2, HDAC activity, and PAR formation assays. Cytotoxicity was assessed by IncuCyte live cell imaging, CellTiter-Glo, and spheroid assays. Cell-cycle profiles were determined using propidium iodide staining and flow cytometry. DNA damage was examined by γH2AX expression and comet assay. Inhibition of metastatic potential by kt-3283 was evaluated via ex vivo pulmonary metastasis assay (PuMA). RESULTS: Compared with FDA-approved PARP (olaparib) and HDAC (vorinostat) inhibitors, kt-3283 displayed enhanced cytotoxicity in Ewing sarcoma models. The kt-3283-induced cytotoxicity was associated with strong S and G2-M cell-cycle arrest in nanomolar concentration range and elevated DNA damage as assessed by γH2AX tracking and comet assays. In three-dimensional spheroid models of Ewing sarcoma, kt-3283 showed efficacy in lower concentrations than olaparib and vorinostat, and kt-3283 inhibited colonization of Ewing sarcoma cells in the ex vivo PuMA model. CONCLUSIONS: Our data demonstrate the preclinical justification for studying the benefit of dual PARP and HDAC inhibition in the treatment of Ewing sarcoma in a clinical trial and provides proof-of-concept for a bifunctional single-molecule therapeutic strategy.
Subject(s)
Puma , Sarcoma, Ewing , Animals , Humans , Poly(ADP-ribose) Polymerase Inhibitors/pharmacology , Poly(ADP-ribose) Polymerase Inhibitors/therapeutic use , Sarcoma, Ewing/pathology , Histone Deacetylase Inhibitors/pharmacology , Histone Deacetylase Inhibitors/therapeutic use , Vorinostat/therapeutic useABSTRACT
Peroxisome proliferator-activated receptor gamma (PPARγ) is a nuclear receptor central in the regulation of key cellular processes including cell metabolism, tissue differentiation, and regulation of the immune system. PPARγ is required for normal differentiation of the urothelium and is thought to be an essential driver of the luminal subtype of bladder cancer. However, the molecular components that regulate PPARG gene expression in bladder cancer remain unclear. Here, we developed an endogenous PPARG reporter system in luminal bladder cancer cells and performed genome-wide CRISPR knockout screening to identify bona fide regulators of PPARG gene expression. Functional validation of the dataset confirmed GATA3, SPT6, and the cohesin complex components SMC1A, and RAD21, as permissive upstream positive regulators of PPARG gene expression in luminal bladder cancer. In summary, this work provides a resource and biological insights to aid our understanding of PPARG regulation in bladder cancer.
ABSTRACT
BACKGROUND: The malaria protein VAR2CSA binds oncofetal chondroitin sulfate (ofCS), a unique chondroitin sulfate, expressed on almost all mammalian cancer cells. Previously, we produced a bispecific construct targeting ofCS and human T cells based on VAR2CSA and anti-CD3 (V-aCD3Hu). V-aCD3Hu showed efficacy against xenografted tumors in immunocompromised mice injected with human immune cells at the tumor site. However, the complex effects potentially exerted by the immune system as a result of the treatment cannot occur in mice without an immune system. Here we investigate the efficacy of V-aCD3Mu as a monotherapy and combined with immune checkpoint inhibitors in mice with a fully functional immune system. METHODS: We produced a bispecific construct consisting of a recombinant version of VAR2CSA coupled to an anti-murine CD3 single-chain variable fragment. Flow cytometry and ELISA were used to check cell binding capabilities and the therapeutic effect was evaluated in vitro in a killing assay. The in vivo efficacy of V-aCD3Mu was then investigated in mice with a functional immune system and established or primary syngeneic tumors in the immunologically "cold" 4T1 mammary carcinoma, B16-F10 malignant melanoma, the pancreatic KPC mouse model, and in the immunologically "hot" CT26 colon carcinoma model. RESULTS: V-aCD3Mu had efficacy as a monotherapy, and the combined treatment of V-aCD3Mu and an immune checkpoint inhibitor showed enhanced effects resulting in the complete elimination of solid tumors in the 4T1, B16-F10, and CT26 models. This anti-tumor effect was abscopal and accompanied by a systemic increase in memory and activated cytotoxic and helper T cells. The combined treatment also led to a higher percentage of memory T cells in the tumor without an increase in regulatory T cells. In addition, we observed partial protection against re-challenge in a melanoma model and full protection in a breast cancer model. CONCLUSIONS: Our findings suggest that V-aCD3Mu combined with an immune checkpoint inhibitor renders immunologically "cold" tumors "hot" and results in tumor elimination. Taken together, these data provide proof of concept for the further clinical development of V-aCD3 as a broad cancer therapy in combination with an immune checkpoint inhibitor.
Subject(s)
Antibodies, Bispecific , Carcinoma , Melanoma, Experimental , Humans , Mice , Animals , Chondroitin Sulfates/pharmacology , Chondroitin Sulfates/metabolism , Immunologic Memory , Immune Checkpoint Inhibitors , Melanoma, Experimental/drug therapy , Carcinoma/drug therapy , Antibodies, Bispecific/pharmacology , Antibodies, Bispecific/therapeutic use , Cell Line, Tumor , Mammals/metabolismABSTRACT
Cancer mortality is exacerbated by late-stage diagnosis. Liquid biopsies based on genomic biomarkers can noninvasively diagnose cancers. However, validation studies have reported ~10% sensitivity to detect stage I cancer in a screening population and specific types, such as brain or genitourinary tumors, remain undetectable. We investigated urine and plasma free glycosaminoglycan profiles (GAGomes) as tumor metabolism biomarkers for multi-cancer early detection (MCED) of 14 cancer types using 2,064 samples from 1,260 cancer or healthy subjects. We observed widespread cancer-specific changes in biofluidic GAGomes recapitulated in an in vivo cancer progression model. We developed three machine learning models based on urine (Nurine = 220 cancer vs. 360 healthy) and plasma (Nplasma = 517 vs. 425) GAGomes that can detect any cancer with an area under the receiver operating characteristic curve of 0.83-0.93 with up to 62% sensitivity to stage I disease at 95% specificity. Undetected patients had a 39 to 50% lower risk of death. GAGomes predicted the putative cancer location with 89% accuracy. In a validation study on a screening-like population requiring ≥ 99% specificity, combined GAGomes predicted any cancer type with poor prognosis within 18 months with 43% sensitivity (21% in stage I; N = 121 and 49 cases). Overall, GAGomes appeared to be powerful MCED metabolic biomarkers, potentially doubling the number of stage I cancers detectable using genomic biomarkers.
Subject(s)
Glycosaminoglycans , Neoplasms , Humans , Biomarkers, Tumor/genetics , Liquid Biopsy , Early Detection of Cancer , Neoplasms/diagnosisABSTRACT
Extracellular matrix (ECM) elasticity is perceived by cells via focal adhesion structures, which transduce mechanical cues into chemical signalling to conform cell behavior. Although the contribution of ECM compliance to the control of cell migration or division is extensively studied, little is reported regarding infectious processes. We study this phenomenon with the extraintestinal Escherichia coli pathogen UTI89. We show that UTI89 takes advantage, via its CNF1 toxin, of integrin mechanoactivation to trigger its invasion into cells. We identify the HACE1 E3 ligase-interacting protein Optineurin (OPTN) as a protein regulated by ECM stiffness. Functional analysis establishes a role of OPTN in bacterial invasion and integrin mechanical coupling and for stimulation of HACE1 E3 ligase activity towards the Rac1 GTPase. Consistent with a role of OPTN in cell mechanics, OPTN knockdown cells display defective integrin-mediated traction force buildup, associated with limited cellular invasion by UTI89. Nevertheless, OPTN knockdown cells display strong mechanochemical adhesion signalling, enhanced Rac1 activation and increased cyclin D1 translation, together with enhanced cell proliferation independent of ECM stiffness. Together, our data ascribe a new function to OPTN in mechanobiology.
Subject(s)
Cyclin D1 , Integrins , Cell Division , Cyclin D1/metabolism , Integrins/metabolism , Mechanotransduction, Cellular/physiology , Ubiquitin-Protein Ligases/metabolism , Ubiquitination , rac1 GTP-Binding Protein/metabolismABSTRACT
Lineage plasticity of prostate cancer is associated with resistance to androgen receptor (AR) pathway inhibition (ARPI) and supported by a reactive tumor microenvironment. Here we show that changes in chondroitin sulfate (CS), a major glycosaminoglycan component of the tumor cell glycocalyx and extracellular matrix, is AR-regulated and promotes the adaptive progression of castration-resistant prostate cancer (CRPC) after ARPI. AR directly represses transcription of the 4-O-sulfotransferase gene CHST11 under basal androgen conditions, maintaining steady-state CS in prostate adenocarcinomas. When AR signaling is inhibited by ARPI or lost during progression to non-AR-driven CRPC as a consequence of lineage plasticity, CHST11 expression is unleashed, leading to elevated 4-O-sulfated chondroitin levels. Inhibition of the tumor cell CS glycocalyx delays CRPC progression, and impairs growth and motility of prostate cancer after ARPI. Thus, a reactive CS glycocalyx supports adaptive survival and treatment resistance after ARPI, representing a therapeutic opportunity in patients with advanced prostate cancer.
Subject(s)
Prostatic Neoplasms, Castration-Resistant , Androgens , Chondroitin Sulfates , Glycocalyx/metabolism , Humans , Male , Prostatic Neoplasms, Castration-Resistant/drug therapy , Signal Transduction , Tumor MicroenvironmentABSTRACT
Proteoglycans are proteins that are modified with glycosaminoglycan chains. Chondroitin sulfate proteoglycans (CSPGs) are currently being exploited as targets for drug-delivery in various cancer indications, however basic knowledge on how CSPGs are internalized in tumor cells is lacking. In this study we took advantage of a recombinant CSPG-binding lectin VAR2CSA (rVAR2) to track internalization and cell fate of CSPGs in tumor cells. We found that rVAR2 is internalized into cancer cells via multiple internalization mechanisms after initial docking on cell surface CSPGs. Regardless of the internalization pathway used, CSPG-bound rVAR2 was trafficked to the early endosomes in an energy-dependent manner but not further transported to the lysosomal compartment. Instead, internalized CSPG-bound rVAR2 proteins were secreted with exosomes to the extracellular environment in a strictly chondroitin sulfate-dependent manner. In summary, our work describes the cell fate of rVAR2 proteins in tumor cells after initial binding to CSPGs, which can be further used to inform development of rVAR2-drug conjugates and other therapeutics targeting CSPGs.
Subject(s)
Chondroitin Sulfate Proteoglycans/metabolism , Lectins/metabolism , Neoplasms/metabolism , Protein Transport , Cell Line, Tumor , Cell Membrane/metabolism , Endosomes/metabolism , Exosomes/metabolism , Humans , Protein Binding , Recombinant Proteins/metabolismABSTRACT
Alternative polyadenylation of mRNA has important but poorly understood roles in development and cancer. Activating mutations in the Ras oncogene are common drivers of many human cancers. From a screen for enhancers of activated Ras (let-60) in Caenorhabditis elegans, we identified cfim-1, a subunit of the alternative polyadenylation machinery. Ablation of cfim-1 increased penetrance of the multivulva phenotype in let-60/Ras gain-of-function (gf) mutants. Depletion of the human cfim-1 ortholog CFIm25/NUDT21 in cancer cells with KRAS mutations increased their migration and stimulated an epithelial-to-mesenchymal transition. CFIm25-depleted cells and cfim-1 mutants displayed biased placement of poly(A) tails to more proximal sites in many conserved transcripts. Functional analysis of these transcripts identified the multidrug resistance protein mrp-5/ABCC1 as a previously unidentified regulator of C. elegans vulva development and cell migration in human cells through alternative 3'UTR usage. Our observations demonstrate a conserved functional role for alternative polyadenylation in oncogenic Ras function.
ABSTRACT
Chimeric antigen receptor (CAR) T cells hold promise for the treatment of acute myeloid leukemia (AML), but optimal targets remain to be defined. We demonstrate that CD93 CAR T cells engineered from a novel humanized CD93-specific binder potently kill AML in vitro and in vivo but spare hematopoietic stem and progenitor cells (HSPC). No toxicity is seen in murine models, but CD93 is expressed on human endothelial cells, and CD93 CAR T cells recognize and kill endothelial cell lines. We identify other AML CAR T-cell targets with overlapping expression on endothelial cells, especially in the context of proinflammatory cytokines. To address the challenge of endothelial-specific cross-reactivity, we provide proof of concept for NOT-gated CD93 CAR T cells that circumvent endothelial cell toxicity in a relevant model system. We also identify candidates for combinatorial targeting by profiling the transcriptome of AML and endothelial cells at baseline and after exposure to proinflammatory cytokines. SIGNIFICANCE: CD93 CAR T cells eliminate AML and spare HSPCs but exert on-target, off-tumor toxicity to endothelial cells. We show coexpression of other AML targets on endothelial cells, introduce a novel NOT-gated strategy to mitigate endothelial toxicity, and demonstrate use of high-dimensional transcriptomic profiling for rational design of combinatorial immunotherapies.See related commentary by Velasquez and Gottschalk, p. 559. This article is highlighted in the In This Issue feature, p. 549.
Subject(s)
Immunotherapy, Adoptive , Leukemia, Myeloid, Acute , Animals , Cell Line, Tumor , Endothelial Cells/pathology , Humans , Immunotherapy, Adoptive/methods , Leukemia, Myeloid, Acute/therapy , Mice , T-LymphocytesABSTRACT
Broad-spectrum therapeutics in non-small cell lung cancer (NSCLC) are in demand. Most human solid tumors express proteoglycans modified with distinct oncofetal chondroitin sulfate (CS) chains that can be detected and targeted with recombinant VAR2CSA (rVAR2) proteins and rVAR2-derived therapeutics. Here, we investigated expression and targetability of oncofetal CS expression in human NSCLC. High oncofetal CS expression is associated with shorter disease-free survival and poor overall survival of clinically annotated stage I and II NSCLC patients (n = 493). Oncofetal CS qualifies as an independent prognosticator of NSCLC in males and smokers, and high oncofetal CS levels are more prevalent in EGFR/KRAS wild-type cases, as compared to mutation cases. NSCLC cell lines express oncofetal CS-modified proteoglycans that can be specifically detected and targeted by rVAR2 proteins in a CSA-dependent manner. Importantly, a novel VAR2-drug conjugate (VDC-MMAE) efficiently eliminates NSCLC cells in vitro and in vivo. In summary, oncofetal CS is a prognostic biomarker and an actionable glycosaminoglycan target in NSCLC.
ABSTRACT
Cisplatin is a widely used antineoplastic agent, whose efficacy is limited by primary and acquired therapeutic resistance. Recently, a bladder cancer genome-wide CRISPR/Cas9 knock-out screen correlated cisplatin sensitivity to multiple genetic biomarkers. Among the screen's top hits was the HECT domain-containing ubiquitin E3 ligase (HUWE1). In this review, HUWE1 is postulated as a therapeutic response modulator, affecting the collision between platinum-DNA adducts and the replication fork, the primary cytotoxic action of platins. HUWE1 can alter the cytotoxic response to platins by targeting essential components of the DNA damage response including BRCA1, p53, and Mcl-1. Deficiency of HUWE1 could lead to enhanced DNA damage repair and a dysfunctional apoptotic apparatus, thereby inducing resistance to platins. Future research on the relationship between HUWE1 and platins could generate new mechanistic insights into therapy resistance. Ultimately, HUWE1 might serve as a clinical biomarker to tailor cancer treatment strategies, thereby improving cancer care and patient outcomes.
Subject(s)
Antineoplastic Agents/pharmacology , Cisplatin/pharmacology , Drug Resistance, Neoplasm , Neoplasms/drug therapy , Tumor Suppressor Proteins/metabolism , Ubiquitin-Protein Ligases/metabolism , Humans , Neoplasms/genetics , Neoplasms/metabolism , Neoplasms/pathology , Tumor Suppressor Proteins/genetics , Ubiquitin-Protein Ligases/genetics , UbiquitinationABSTRACT
Cancer cells must overcome anoikis (detachment-induced death) to successfully metastasize. Using proteomic screens, we found that distinct oncoproteins upregulate IL1 receptor accessory protein (IL1RAP) to suppress anoikis. IL1RAP is directly induced by oncogenic fusions of Ewing sarcoma, a highly metastatic childhood sarcoma. IL1RAP inactivation triggers anoikis and impedes metastatic dissemination of Ewing sarcoma cells. Mechanistically, IL1RAP binds the cell-surface system Xc - transporter to enhance exogenous cystine uptake, thereby replenishing cysteine and the glutathione antioxidant. Under cystine depletion, IL1RAP induces cystathionine gamma lyase (CTH) to activate the transsulfuration pathway for de novo cysteine synthesis. Therefore, IL1RAP maintains cyst(e)ine and glutathione pools, which are vital for redox homeostasis and anoikis resistance. IL1RAP is minimally expressed in pediatric and adult normal tissues, and human anti-IL1RAP antibodies induce potent antibody-dependent cellular cytotoxicity of Ewing sarcoma cells. Therefore, we define IL1RAP as a new cell-surface target in Ewing sarcoma, which is potentially exploitable for immunotherapy. SIGNIFICANCE: Here, we identify cell-surface protein IL1RAP as a key driver of metastasis in Ewing sarcoma, a highly aggressive childhood sarcoma. Minimal expression in pediatric and adult normal tissues nominates IL1RAP as a promising target for immunotherapy.See related commentary by Yoon and DeNicola, p. 2679.This article is highlighted in the In This Issue feature, p. 2659.
Subject(s)
Anoikis , Interleukin-1 Receptor Accessory Protein , Sarcoma, Ewing , Adult , Cell Line, Tumor , Child , Humans , Proteomics , Receptors, Interleukin-1 , Sarcoma, Ewing/genetics , Sarcoma, Ewing/metabolism , Sarcoma, Ewing/pathologyABSTRACT
As an immune evasion and survival strategy, the Plasmodium falciparum malaria parasite has evolved a protein named VAR2CSA. This protein mediates sequestration of infected red blood cells in the placenta through the interaction with a unique carbohydrate abundantly and exclusively present in the placenta. Cancer cells were found to share the same expression of this distinct carbohydrate, termed oncofetal chondroitin sulfate on their surface. In this study we have used a protein conjugation system to produce a bispecific immune engager, V-aCD3, based on recombinant VAR2CSA as the cancer targeting moiety and an anti-CD3 single-chain variable fragment linked to a single-chain Fc as the immune engager. Conjugation of these two proteins resulted in a single functional moiety that induced immune mediated killing of a broad range of cancer cells in vitro and facilitated tumor arrest in an orthotopic bladder cancer xenograft model.
Subject(s)
Erythrocytes/metabolism , Malaria, Falciparum/metabolism , Protozoan Proteins/metabolism , Chondroitin Sulfates/immunology , Chondroitin Sulfates/metabolism , Female , Humans , Malaria/immunology , Malaria/metabolism , Malaria, Falciparum/immunology , Placenta/metabolism , Plasmodium falciparum/metabolism , Pregnancy , Protozoan Proteins/immunology , Recombinant Proteins/metabolismABSTRACT
Uncovering the mechanisms that underpin how tumor cells adapt to microenvironmental stress is essential to better understand cancer progression. The HACE1 (HECT domain and ankyrin repeat-containing E3 ubiquitin-protein ligase) gene is a tumor suppressor that inhibits the growth, invasive capacity, and metastasis of cancer cells. However, the direct regulatory pathways whereby HACE1 confers this tumor-suppressive effect remain to be fully elucidated. In this report, we establish a link between HACE1 and the major stress factor, hypoxia-inducible factor 1 alpha (HIF1α). We find that HACE1 blocks the accumulation of HIF1α during cellular hypoxia through decreased protein stability. This property is dependent on HACE1 E3 ligase activity and loss of Ras-related C3 botulinum toxin substrate 1 (RAC1), an established target of HACE1 mediated ubiquitinylation and degradation. In vivo, genetic deletion of Rac1 reversed the increased HIF1α expression observed in Hace1-/- mice in murine KRasG12D-driven lung tumors. An inverse relationship was observed between HACE1 and HIF1α levels in tumors compared to patient-matched normal kidney tissues, highlighting the potential pathophysiological significance of our findings. Together, our data uncover a previously unrecognized function for the HACE1 tumor suppressor in blocking HIF1α accumulation under hypoxia in a RAC1-dependent manner.
Subject(s)
Hypoxia-Inducible Factor 1, alpha Subunit/genetics , Lung Neoplasms/genetics , Tumor Suppressor Proteins/genetics , Ubiquitin-Protein Ligases/genetics , rac1 GTP-Binding Protein/genetics , Animals , Cell Line, Tumor , Gene Expression Regulation, Neoplastic/genetics , Humans , Lung Neoplasms/pathology , Mice , Mice, Knockout , Neoplasm Metastasis , Protein Stability , Signal Transduction/genetics , Tumor Hypoxia/genetics , Ubiquitination/geneticsABSTRACT
Proteoglycans in bladder tumors are modified with a distinct oncofetal chondroitin sulfate (ofCS) glycosaminoglycan that is normally restricted to placental trophoblast cells. This ofCS-modification can be detected in bladder tumors by the malarial VAR2CSA protein, which in malaria pathogenesis mediates adherence of parasite-infected erythrocytes within the placenta. In bladder cancer, proteoglycans are constantly shed into the urine, and therefore have the potential to be used for detection of disease. In this study we investigated whether recombinant VAR2CSA (rVAR2) protein could be used to detect ofCS-modified proteoglycans (ofCSPGs) in the urine of bladder cancer patients as an indication of disease presence. We show that ofCSPGs in bladder cancer urine can be immobilized on cationic nitrocellulose membranes and subsequently probed for ofCS content by rVAR2 protein in a custom-made dot-blot assay. Patients with high-grade bladder tumors displayed a marked increase in urinary ofCSPGs as compared to healthy individuals. Urine ofCSPGs decreased significantly after complete tumor resection compared to matched urine collected preoperatively from patients with bladder cancer. Moreover, ofCSPGs in urine correlated with tumor size of bladder cancer patients. These findings demonstrate that rVAR2 can be utilized in a simple biochemical assay to detect cancer-specific ofCS-modifications in the urine of bladder cancer patients, which may be further developed as a noninvasive approach to detect and monitor the disease.
ABSTRACT
1,2:5,6-Dianhydrogalactitol (DAG) is a bi-functional DNA-targeting agent currently in phase II clinical trial for treatment of temozolomide-resistant glioblastoma (GBM). In the present study, we investigated the cytotoxic activity of DAG alone or in combination with common chemotherapy agents in GBM and prostate cancer (PCa) cells, and determined the impact of DNA repair pathways on DAG-induced cytotoxicity. We found that DAG produced replication-dependent DNA lesions decorated with RPA32, RAD51, and γH2AX foci. DAG-induced cytotoxicity was unaffected by MLH1, MSH2, and DNA-PK expression, but was enhanced by knockdown of BRCA1. Acting in S phase, DAG displayed selective synergy with topoisomerase I (camptothecin and irinotecan) and topoisomerase II (etoposide) poisons in GBM, PCa, and lung cancer cells with no synergy observed for docetaxel. Importantly, DAG combined with irinotecan treatment enhanced tumor responses and prolonged survival of tumor-bearing mice. This work provides mechanistic insight into DAG cytotoxicity in GBM and PCa cells and offers a rational for exploring combination regimens with topoisomerase I/II poisons in future clinical trials.
Subject(s)
DNA Repair , Dianhydrogalactitol/pharmacology , Topoisomerase Inhibitors/pharmacology , Animals , Cell Cycle Checkpoints/drug effects , Cell Death/drug effects , Cell Line, Tumor , DNA Damage , DNA Repair/drug effects , DNA Replication/drug effects , Drug Synergism , G2 Phase/drug effects , HEK293 Cells , Humans , Irinotecan/pharmacology , Male , Mice, Nude , Recombinational DNA Repair/drug effects , S Phase/drug effects , Xenograft Model Antitumor AssaysABSTRACT
HACE1 is an E3 ubiquitin ligase with important roles in tumor biology and tissue homeostasis. Loss or mutation of HACE1 has been associated with the occurrence of a variety of neoplasms, but the underlying mechanisms have not been defined yet. Here, we report that HACE1 is frequently mutated in human lung cancer. In mice, loss of Hace1 led to enhanced progression of KRasG12D -driven lung tumors. Additional ablation of the oncogenic GTPase Rac1 partially reduced progression of Hace1-/- lung tumors. RAC2, a novel ubiquitylation target of HACE1, could compensate for the absence of its homolog RAC1 in Hace1-deficient, but not in HACE1-sufficient tumors. Accordingly, ablation of both Rac1 and Rac2 fully averted the increased progression of KRasG12D -driven lung tumors in Hace1-/- mice. In patients with lung cancer, increased expression of HACE1 correlated with reduced levels of RAC1 and RAC2 and prolonged survival, whereas elevated expression of RAC1 and RAC2 was associated with poor prognosis. This work defines HACE1 as a crucial regulator of the oncogenic activity of RAC-family GTPases in lung cancer development. SIGNIFICANCE: These findings reveal that mutation of the tumor suppressor HACE1 disrupts its role as a regulator of the oncogenic activity of RAC-family GTPases in human and murine lung cancer. GRAPHICAL ABSTRACT: http://cancerres.aacrjournals.org/content/canres/80/14/3009/F1.large.jpg.