Publications by authors named "Fabio Stossi"

53 Publications

Phenotypic and protein localization heterogeneity associated with AHDC1 pathogenic protein-truncating alleles in Xia-Gibbs syndrome.

Hum Mutat 2021 Feb 28. Epub 2021 Feb 28.

Human Genome Sequencing Center, Baylor College of Medicine, Houston, Texas, USA.

Xia-Gibbs syndrome (XGS) is a rare Mendelian disease typically caused by de novo stop-gain or frameshift mutations in the AT-hook DNA binding motif containing 1 (AHDC1) gene. Patients usually present in early infancy with hypotonia and developmental delay and later exhibit intellectual disability (ID). The overall presentation is variable, however, and the emerging clinical picture is still evolving. A detailed phenotypic analysis of 34 XGS individuals revealed five core phenotypes (delayed motor milestones, speech delay, low muscle tone, ID, and hypotonia) in more than 80% of individuals and an additional 12 features that occurred more variably. Seizures and scoliosis were more frequently associated with truncations that arise before the midpoint of the protein although the occurrence of most features could not be predicted by the mutation position. Transient expression of wild type and different patient truncated AHDC1 protein forms in human cell lines revealed abnormal patterns of nuclear localization including a diffuse distribution of a short truncated form and nucleolar aggregation in mid-protein truncated forms. Overall, both the occurrence of variable phenotypes and the different distribution of the expressed protein reflect the heterogeneity of this syndrome.
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http://dx.doi.org/10.1002/humu.24190DOI Listing
February 2021

Targeted brachyury degradation disrupts a highly specific autoregulatory program controlling chordoma cell identity.

Cell Rep Med 2021 Jan 19;2(1):100188. Epub 2021 Jan 19.

Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX 77030, USA.

Chordomas are rare spinal tumors addicted to expression of the developmental transcription factor brachyury. In chordomas, brachyury is super-enhancer associated and preferentially downregulated by pharmacologic transcriptional CDK inhibition, leading to cell death. To understand the underlying basis of this sensitivity, we dissect the brachyury transcription regulatory network and compare the consequences of brachyury degradation with transcriptional CDK inhibition. Brachyury defines the chordoma super-enhancer landscape and autoregulates through binding its super-enhancer, and its locus forms a transcriptional condensate. Transcriptional CDK inhibition and brachyury degradation disrupt brachyury autoregulation, leading to loss of its transcriptional condensate and transcriptional program. Compared with transcriptional CDK inhibition, which globally downregulates transcription, leading to cell death, brachyury degradation is much to anti-apoptotic inhibition. These data suggest that brachyury downregulation is a core tenet of transcriptional CDK inhibition and motivates developing strategies to target brachyury and its autoregulatory feedback loop.
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http://dx.doi.org/10.1016/j.xcrm.2020.100188DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7817874PMC
January 2021

Spliceosome-targeted therapies trigger an antiviral immune response in triple-negative breast cancer.

Cell 2021 Jan 14;184(2):384-403.e21. Epub 2021 Jan 14.

Verna and Marrs McLean Department of Biochemistry and Molecular Biology, Baylor College of Medicine, Houston, TX 77030, USA; Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX 77030, USA; Lester and Sue Smith Breast Center, Baylor College of Medicine, Houston, TX 77030, USA; Department of Molecular and Cellular Biology, Baylor College of Medicine, Houston, TX 77030, USA; Therapeutic Innovation Center, Baylor College of Medicine, Houston, TX 77030, USA. Electronic address:

Many oncogenic insults deregulate RNA splicing, often leading to hypersensitivity of tumors to spliceosome-targeted therapies (STTs). However, the mechanisms by which STTs selectively kill cancers remain largely unknown. Herein, we discover that mis-spliced RNA itself is a molecular trigger for tumor killing through viral mimicry. In MYC-driven triple-negative breast cancer, STTs cause widespread cytoplasmic accumulation of mis-spliced mRNAs, many of which form double-stranded structures. Double-stranded RNA (dsRNA)-binding proteins recognize these endogenous dsRNAs, triggering antiviral signaling and extrinsic apoptosis. In immune-competent models of breast cancer, STTs cause tumor cell-intrinsic antiviral signaling, downstream adaptive immune signaling, and tumor cell death. Furthermore, RNA mis-splicing in human breast cancers correlates with innate and adaptive immune signatures, especially in MYC-amplified tumors that are typically immune cold. These findings indicate that dsRNA-sensing pathways respond to global aberrations of RNA splicing in cancer and provoke the hypothesis that STTs may provide unexplored strategies to activate anti-tumor immune pathways.
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http://dx.doi.org/10.1016/j.cell.2020.12.031DOI Listing
January 2021

Single Cell Analysis Of Transcriptionally Active Alleles By Single Molecule FISH.

J Vis Exp 2020 09 20(163). Epub 2020 Sep 20.

GCC Center for Advanced Microscopy and Image Informatics; Department of Molecular and Cellular Biology, Baylor College of Medicine; Center for Translational Cancer Research, Institute of Biosciences and Technology, Texas A&M University; Department of Pharmacology and Chemical Biology, Baylor College of Medicine.

Gene transcription is an essential process in cell biology, and allows cells to interpret and respond to internal and external cues. Traditional bulk population methods (Northern blot, PCR, and RNAseq) that measure mRNA levels lack the ability to provide information on cell-to-cell variation in responses. Precise single cell and allelic visualization and quantification is possible via single molecule RNA fluorescence in situ hybridization (smFISH). RNA-FISH is performed by hybridizing target RNAs with labeled oligonucleotide probes. These can be imaged in medium/high throughput modalities, and, through image analysis pipelines, provide quantitative data on both mature and nascent RNAs, all at the single cell level. The fixation, permeabilization, hybridization and imaging steps have been optimized in the lab over many years using the model system described herein, which results in successful and robust single cell analysis of smFISH labeling. The main goal with sample preparation and processing is to produce high quality images characterized by a high signal-to-noise ratio to reduce false positives and provide data that are more accurate. Here, we present a protocol describing the pipeline from sample preparation to data analysis in conjunction with suggestions and optimization steps to tailor to specific samples.
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http://dx.doi.org/10.3791/61680DOI Listing
September 2020

Classification of estrogenic compounds by coupling high content analysis and machine learning algorithms.

PLoS Comput Biol 2020 09 24;16(9):e1008191. Epub 2020 Sep 24.

Texas A&M Energy Institute, Texas A&M University, College Station, TX, United States of America.

Environmental toxicants affect human health in various ways. Of the thousands of chemicals present in the environment, those with adverse effects on the endocrine system are referred to as endocrine-disrupting chemicals (EDCs). Here, we focused on a subclass of EDCs that impacts the estrogen receptor (ER), a pivotal transcriptional regulator in health and disease. Estrogenic activity of compounds can be measured by many in vitro or cell-based high throughput assays that record various endpoints from large pools of cells, and increasingly at the single-cell level. To simultaneously capture multiple mechanistic ER endpoints in individual cells that are affected by EDCs, we previously developed a sensitive high throughput/high content imaging assay that is based upon a stable cell line harboring a visible multicopy ER responsive transcription unit and expressing a green fluorescent protein (GFP) fusion of ER. High content analysis generates voluminous multiplex data comprised of minable features that describe numerous mechanistic endpoints. In this study, we present a machine learning pipeline for rapid, accurate, and sensitive assessment of the endocrine-disrupting potential of benchmark chemicals based on data generated from high content analysis. The multidimensional imaging data was used to train a classification model to ultimately predict the impact of unknown compounds on the ER, either as agonists or antagonists. To this end, both linear logistic regression and nonlinear Random Forest classifiers were benchmarked and evaluated for predicting the estrogenic activity of unknown compounds. Furthermore, through feature selection, data visualization, and model discrimination, the most informative features were identified for the classification of ER agonists/antagonists. The results of this data-driven study showed that highly accurate and generalized classification models with a minimum number of features can be constructed without loss of generality, where these machine learning models serve as a means for rapid mechanistic/phenotypic evaluation of the estrogenic potential of many chemicals.
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http://dx.doi.org/10.1371/journal.pcbi.1008191DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7538107PMC
September 2020

Unique cellular protrusions mediate breast cancer cell migration by tethering to osteogenic cells.

NPJ Breast Cancer 2020 7;6:42. Epub 2020 Sep 7.

Lester and Sue Smith Breast Center, Baylor College of Medicine, One Baylor Plaza, Houston, TX 77030 USA.

Migration and invasion are key properties of metastatic cancer cells. These properties can be acquired through intrinsic reprogramming processes such as epithelial-mesenchymal transition. In this study, we discovered an alternative "migration-by-tethering" mechanism through which cancer cells gain the momentum to migrate by adhering to mesenchymal stem cells or osteoblasts. This tethering is mediated by both heterotypic adherens junctions and gap junctions, and leads to a unique cellular protrusion supported by cofilin-coated actin filaments. Inhibition of gap junctions or depletion of cofilin reduces migration-by-tethering. We observed evidence of these protrusions in bone segments harboring experimental and spontaneous bone metastasis in animal models. These data exemplify how cancer cells may acquire migratory ability without intrinsic reprogramming. Furthermore, given the important roles of osteogenic cells in early-stage bone colonization, our observations raise the possibility that migration-by-tethering may drive the relocation of disseminated tumor cells between different niches in the bone microenvironment.
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http://dx.doi.org/10.1038/s41523-020-00183-8DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7477119PMC
September 2020

Correction: Epigenetic loss of AOX1 expression via EZH2 leads to metabolic deregulations and promotes bladder cancer progression.

Oncogene 2020 Oct;39(40):6387-6392

Department of Molecular and Cellular Biology, Baylor College of Medicine, Houston, TX, USA.

After publication of this Article, the Authors noticed errors in some of the Figures. In Figures 2e, 2f-g, 4a, 4j, 5a and 6b, unmatched β-actin was inadvertently used as loading control for the immunoblots. These have been corrected using repeat data from a similar set of samples and the revised Figures containing matched β-actin and their respective quantification data are included below. In Figure 7a, the same image was inadvertently used to represent tumors 3 and 5 in the control group. This error has been corrected using original images of tumors 3 and 5 in the control group. Additional corrections have been made in the Article and Figure legends to enhance the clarity of the description. NAD was replaced by NADP. NAD/NADP was replaced by NADP/NADPH. The description of the antibody source and dilution for the antigens PFKFB4 (Abcam, 1:1000), G6PD, and HK1 (Cell Signaling, 1:1,000) have been included in the Methods section for Western Blot. The legend for Figure 4e and 4j has been updated. The HTML and PDF versions of this Article have been corrected. The scientific conclusions of this paper have not been affected.
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http://dx.doi.org/10.1038/s41388-020-1283-7DOI Listing
October 2020

Acquisition of Cisplatin Resistance Shifts Head and Neck Squamous Cell Carcinoma Metabolism toward Neutralization of Oxidative Stress.

Cancers (Basel) 2020 Jun 24;12(6). Epub 2020 Jun 24.

Bobby R. Alford Department of Otolaryngology Head and Neck Surgery, Baylor College of Medicine, Houston, TX 77030, USA.

: Cisplatin (CDDP) is commonly utilized in the treatment of advanced solid tumors including head and neck squamous cell carcinoma (HNSCC). Cisplatin response remains highly variable among individual tumors and development of cisplatin resistance is common. We hypothesized that development of cisplatin resistance is partially driven by metabolic reprogramming. : Using a pre-clinical HNSCC model and an integrated approach to steady state metabolomics, metabolic flux and gene expression data we characterized the interaction between cisplatin resistance and metabolic reprogramming. : Cisplatin toxicity in HNSCC was driven by generation of intra-cellular oxidative stress. This was validated by demonstrating that acquisition of cisplatin resistance generates cross-resistance to ferroptosis agonists despite the fact that cisplatin itself does not trigger ferroptosis. Acquisition of cisplatin resistance dysregulated the expression of genes involved in amino acid, fatty acid metabolism and central carbon catabolic pathways, enhanced glucose catabolism and serine synthesis. Acute cisplatin exposure increased intra-tumoral levels of S-methyl-5-thiadenosine (MTA) precursors and metabotoxins indicative of generalized oxidative stress. Acquisition of cisplatin resistance is linked to metabolic recovery from oxidative stress. Although this portends poor effectiveness for directed metabolic targeting, it supports the potential for biomarker development of cisplatin effectiveness using an integrated approach.
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http://dx.doi.org/10.3390/cancers12061670DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7352569PMC
June 2020

Single-Cell Distribution Analysis of AR Levels by High-Throughput Microscopy in Cell Models: Application for Testing Endocrine-Disrupting Chemicals.

SLAS Discov 2020 08 18;25(7):684-694. Epub 2020 Jun 18.

Department of Molecular and Cellular Biology, Baylor College of Medicine, Houston, TX, USA.

Cell-to-cell variation of protein expression in genetically homogeneous populations is a common biological trait often neglected during analysis of high-throughput (HT) screens and is rarely used as a metric to characterize chemicals. We have captured single-cell distributions of androgen receptor (AR) nuclear levels after perturbations as a means to evaluate assay reproducibility and characterize a small subset of chemicals. AR, a member of the nuclear receptor family of transcription factors, is the central regulator of male reproduction and is involved in many pathophysiological processes. AR protein levels and nuclear localization often increase following ligand binding, with dihydrotestosterone (DHT) being the natural agonist. HT AR immunofluorescence imaging was used in multiple cell lines to define single-cell nuclear values extracted from thousands of cells per condition treated with DHT or DMSO (control). Analysis of numerous biological replicates led to a quality control metric that takes into account the distribution of single-cell data, and how it changes upon treatments. Dose-response experiments across several cell lines showed a large range of sensitivity to DHT, prompting us to treat selected cell lines with 45 Environmental Protection Agency (EPA)-provided chemicals that include many endocrine-disrupting chemicals (EDCs); data from six of the compounds were then integrated with orthogonal assays. Our comprehensive results indicate that quantitative single-cell distribution analysis of AR protein levels is a valid method to detect the potential androgenic and antiandrogenic actions of environmentally relevant chemicals in a sensitive and reproducible manner.
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http://dx.doi.org/10.1177/2472555220934420DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7430197PMC
August 2020

A Genetically Engineered Rotavirus NSP2 Phosphorylation Mutant Impaired in Viroplasm Formation and Replication Shows an Early Interaction between vNSP2 and Cellular Lipid Droplets.

J Virol 2020 07 16;94(15). Epub 2020 Jul 16.

Department of Molecular Virology and Microbiology, Baylor College of Medicine, Houston, Texas, USA

Many RNA viruses replicate in cytoplasmic compartments (virus factories or viroplasms) composed of viral and cellular proteins, but the mechanisms required for their formation remain largely unknown. Rotavirus (RV) replication in viroplasms requires interactions between virus nonstructural proteins NSP2 and NSP5, which are associated with components of lipid droplets (LDs). We previously identified two forms of NSP2 in RV-infected cells, a cytoplasmically dispersed form (dNSP2) and a viroplasm-specific form (vNSP2), which interact with hypophosphorylated and hyperphosphorylated NSP5, respectively, indicating that a coordinated phosphorylation cascade controls viroplasm assembly. The cellular kinase CK1α phosphorylates NSP2 on serine 313, triggering the localization of vNSP2 to sites of viroplasm assembly and its association with hyperphosphorylated NSP5. Using reverse genetics, we generated a rotavirus with a phosphomimetic NSP2 (S313D) mutation to directly evaluate the role of CK1α NSP2 phosphorylation in viroplasm formation. Recombinant rotavirus NSP2 S313D (rRV NSP2 S313D) is significantly delayed in viroplasm formation and in virus replication and interferes with wild-type RV replication in coinfection. Taking advantage of the delay in viroplasm formation, the NSP2 phosphomimetic mutant was used as a tool to observe very early events in viroplasm assembly. We show that (i) viroplasm assembly correlates with NSP5 hyperphosphorylation and (ii) vNSP2 S313D colocalizes with RV-induced LDs without NSP5, suggesting that vNSP2 phospho-S313 is sufficient for interacting with LDs and may be the virus factor required for RV-induced LD formation. Further studies with the rRV NSP2 S313D virus are expected to reveal new aspects of viroplasm and LD initiation and assembly. Reverse genetics was used to generate a recombinant rotavirus with a single phosphomimetic mutation in nonstructural protein 2 (NSP2 S313D) that exhibits delayed viroplasm formation, delayed replication, and an interfering phenotype during coinfection with wild-type rotavirus, indicating the importance of this amino acid during virus replication. Exploiting the delay in viroplasm assembly, we found that viroplasm-associated NSP2 colocalizes with rotavirus-induced lipid droplets prior to the accumulation of other rotavirus proteins that are required for viroplasm formation and that NSP5 hyperphosphorylation is required for viroplasm assembly. These data suggest that NSP2 phospho-S313 is sufficient for interaction with lipid droplets and may be the virus factor that induces lipid droplet biogenesis in rotavirus-infected cells. Lipid droplets are cellular organelles critical for the replication of many viral and bacterial pathogens, and thus, understanding the mechanism of NSP2-mediated viroplasm/lipid droplet initiation and interaction will lead to new insights into this important host-pathogen interaction.
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http://dx.doi.org/10.1128/JVI.00972-20DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7375380PMC
July 2020

A Mechanistic High-Content Analysis Assay Using a Chimeric Androgen Receptor That Rapidly Characterizes Androgenic Chemicals.

SLAS Discov 2020 08 11;25(7):695-708. Epub 2020 May 11.

Molecular and Cellular Biology, Baylor College of Medicine, Houston, TX, USA.

Human health is at risk from environmental exposures to a wide range of chemical toxicants and endocrine-disrupting chemicals (EDCs). As part of understanding this risk, the U.S. Environmental Protection Agency (EPA) has been pursuing new high-throughput in vitro assays and computational models to characterize EDCs. EPA models have incorporated our high-content analysis-based green fluorescent protein estrogen receptor (GFP-ER): PRL-HeLa assay, which allows direct visualization of ER binding to DNA regulatory elements. Here, we characterize a modified functional assay based on the stable expression of a chimeric androgen receptor (ARER), wherein a region containing the native AR DNA-binding domain (DBD) was replaced with the ERα DBD (amino acids 183-254). We demonstrate that the AR agonist dihydrotestosterone induces GFP-ARER nuclear translocation, PRL promoter binding, and transcriptional activity at physiologically relevant concentrations (<1 nM). In contrast, the AR antagonist bicalutamide induces only nuclear translocation of the GFP-ARER receptor (at μM concentrations). Estradiol also fails to induce visible chromatin binding, indicating androgen specificity. In a screen of reference chemicals from the EPA and the Agency for Toxic Substances and Disease Registry, the GFP-ARER cell model identified and mechanistically grouped activity by known (anti-)androgens based on the ability to induce nuclear translocation and/or chromatin binding. Finally, the cell model was used to identify potential (anti-)androgens in environmental samples in collaboration with the Houston Ship Channel/Galveston Bay Texas A&M University EPA Superfund Research Program. Based on these data, the chromatin-binding, in vitro assay-based GFP-ARER model represents a selective tool for rapidly identifying androgenic activity associated with drugs, chemicals, and environmental samples.
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http://dx.doi.org/10.1177/2472555220922917DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7477889PMC
August 2020

Estrogen-induced transcription at individual alleles is independent of receptor level and active conformation but can be modulated by coactivators activity.

Nucleic Acids Res 2020 02;48(4):1800-1810

Department of Molecular and Cellular Biology, Baylor College of Medicine, Houston, TX 77030, USA.

Steroid hormones are pivotal modulators of pathophysiological processes in many organs, where they interact with nuclear receptors to regulate gene transcription. However, our understanding of hormone action at the single cell level remains incomplete. Here, we focused on estrogen stimulation of the well-characterized GREB1 and MYC target genes that revealed large differences in cell-by-cell responses, and, more interestingly, between alleles within the same cell, both over time and hormone concentration. We specifically analyzed the role of receptor level and activity state during allele-by-allele regulation and found that neither receptor level nor activation status are the determinant of maximal hormonal response, indicating that additional pathways are potentially in place to modulate cell- and allele-specific responses. Interestingly, we found that a small molecule inhibitor of the arginine methyltransferases CARM1 and PRMT6 was able to increase, in a gene specific manner, the number of active alleles/cell before and after hormonal stimulation, suggesting that mechanisms do indeed exist to modulate hormone receptor responses at the single cell and allele level.
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http://dx.doi.org/10.1093/nar/gkz1172DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7039002PMC
February 2020

The SINEB1 element in the long non-coding RNA Malat1 is necessary for TDP-43 proteostasis.

Nucleic Acids Res 2020 03;48(5):2621-2642

Department of Molecular and Cellular Biology, Baylor College of Medicine, Houston, TX 77030, USA.

Transposable elements (TEs) comprise a large proportion of long non-coding RNAs (lncRNAs). Here, we employed CRISPR to delete a short interspersed nuclear element (SINE) in Malat1, a cancer-associated lncRNA, to investigate its significance in cellular physiology. We show that Malat1 with a SINE deletion forms diffuse nuclear speckles and is frequently translocated to the cytoplasm. SINE-deleted cells exhibit an activated unfolded protein response and PKR and markedly increased DNA damage and apoptosis caused by dysregulation of TDP-43 localization and formation of cytotoxic inclusions. TDP-43 binds stronger to Malat1 without the SINE and is likely 'hijacked' by cytoplasmic Malat1 to the cytoplasm, resulting in the depletion of nuclear TDP-43 and redistribution of TDP-43 binding to repetitive element transcripts and mRNAs encoding mitotic and nuclear-cytoplasmic regulators. The SINE promotes Malat1 nuclear retention by facilitating Malat1 binding to HNRNPK, a protein that drives RNA nuclear retention, potentially through direct interactions of the SINE with KHDRBS1 and TRA2A, which bind to HNRNPK. Losing these RNA-protein interactions due to the SINE deletion likely creates more available TDP-43 binding sites on Malat1 and subsequent TDP-43 aggregation. These results highlight the significance of lncRNA TEs in TDP-43 proteostasis with potential implications in both cancer and neurodegenerative diseases.
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http://dx.doi.org/10.1093/nar/gkz1176DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7049706PMC
March 2020

Tributyltin chloride (TBT) induces RXRA down-regulation and lipid accumulation in human liver cells.

PLoS One 2019 11;14(11):e0224405. Epub 2019 Nov 11.

Department of Molecular and Cellular Biology, Baylor College of Medicine, Houston, TX, United States of America.

A subset of environmental chemicals acts as "obesogens" as they increase adipose mass and lipid content in livers of treated rodents. One of the most studied class of obesogens are the tin-containing chemicals that have as a central moiety tributyltin (TBT), which bind and activate two nuclear hormone receptors, Peroxisome Proliferator Activated Receptor Gamma (PPARG) and Retinoid X Receptor Alpha (RXRA), at nanomolar concentrations. Here, we have tested whether TBT chloride at such concentrations may affect the neutral lipid level in two cell line models of human liver. Indeed, using high content image analysis (HCA), TBT significantly increased neutral lipid content in a time- and concentration-dependent manner. Consistent with the observed increased lipid accumulation, RNA fluorescence in situ hybridization (RNA FISH) and RT-qPCR experiments revealed that TBT enhanced the steady-state mRNA levels of two key genes for de novo lipogenesis, the transcription factor SREBF1 and its downstream enzymatic target, FASN. Importantly, pre-treatment of cells with 2-deoxy-D-glucose reduced TBT-mediated lipid accumulation, thereby suggesting a role for active glycolysis during the process of lipid accumulation. As other RXRA binding ligands can promote RXRA protein turnover via the 26S proteasome, TBT was tested for such an effect in the two liver cell lines. We found that TBT, in a time- and dose-dependent manner, significantly reduced steady-state RXRA levels in a proteasome-dependent manner. While TBT promotes both RXRA protein turnover and lipid accumulation, we found no correlation between these two events at the single cell level, thereby suggesting an additional mechanism may be involved in TBT promotion of lipid accumulation, such as glycolysis.
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http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0224405PLOS
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6844554PMC
March 2020

The Signaling Pathways Project, an integrated 'omics knowledgebase for mammalian cellular signaling pathways.

Sci Data 2019 10 31;6(1):252. Epub 2019 Oct 31.

Department of Molecular and Cellular Biology, Baylor College of Medicine, Houston, Texas, 77030, USA.

Mining of integrated public transcriptomic and ChIP-Seq (cistromic) datasets can illuminate functions of mammalian cellular signaling pathways not yet explored in the research literature. Here, we designed a web knowledgebase, the Signaling Pathways Project (SPP), which incorporates community classifications of signaling pathway nodes (receptors, enzymes, transcription factors and co-nodes) and their cognate bioactive small molecules. We then mapped over 10,000 public transcriptomic or cistromic experiments to their pathway node or biosample of study. To enable prediction of pathway node-gene target transcriptional regulatory relationships through SPP, we generated consensus 'omics signatures, or consensomes, which ranked genes based on measures of their significant differential expression or promoter occupancy across transcriptomic or cistromic experiments mapped to a specific node family. Consensomes were validated using alignment with canonical literature knowledge, gene target-level integration of transcriptomic and cistromic data points, and in bench experiments confirming previously uncharacterized node-gene target regulatory relationships. To expose the SPP knowledgebase to researchers, a web browser interface was designed that accommodates numerous routine data mining strategies. SPP is freely accessible at https://www.signalingpathways.org .
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http://dx.doi.org/10.1038/s41597-019-0193-4DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6823428PMC
October 2019

Development of the Texas A&M Superfund Research Program Computational Platform for Data Integration, Visualization, and Analysis.

ESCAPE 2019 25;46:967-972. Epub 2019 Jul 25.

Artie McFerrin Department of Chemical Engineering, Texas A&M University, College Station, TX.

The National Institute of Environmental Health Sciences (NIEHS) Superfund Research Program (SRP) aims to support university-based multidisciplinary research on human health and environmental issues related to hazardous substances and pollutants. The Texas A&M Superfund Research Program comprehensively evaluates the complexities of hazardous chemical mixtures and their potential adverse health impacts due to exposure through a number of multi-disciplinary projects and cores. One of the essential components of the Texas A&M Superfund Research Center is the Data Science Core, which serves as the basis for translating the data produced by the multi-disciplinary research projects into useful knowledge for the community via data collection, quality control, analysis, and model generation. In this work, we demonstrate the Texas A&M Superfund Research Program computational platform, which houses and integrates large-scale, diverse datasets generated across the Center, provides basic visualization service to facilitate interpretation, monitors data quality, and finally implements a variety of state-of-the-art statistical analysis for model/tool development. The platform is aimed to facilitate effective integration and collaboration across the Center and acts as an enabler for the dissemination of comprehensive ad-hoc tools and models developed to address the environmental and health effects of chemical mixture exposure during environmental emergency-related contamination events.
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http://dx.doi.org/10.1016/B978-0-12-818634-3.50162-4DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6791821PMC
July 2019

Epigenetic loss of AOX1 expression via EZH2 leads to metabolic deregulations and promotes bladder cancer progression.

Oncogene 2020 10 5;39(40):6265-6285. Epub 2019 Aug 5.

Department of Molecular and Cellular Biology, Baylor College of Medicine, Houston, TX, USA.

Advanced Bladder Cancer (BLCA) remains a clinical challenge that lacks effective therapeutic measures. Here, we show that distinct, stage-wise metabolic alterations in BLCA are associated with the loss of function of aldehyde oxidase (AOX1). AOX1 associated metabolites have a high predictive value for advanced BLCA and our findings demonstrate that AOX1 is epigenetically silenced during BLCA progression by the methyltransferase activity of EZH2. Knockdown (KD) of AOX1 in normal bladder epithelial cells re-wires the tryptophan-kynurenine pathway resulting in elevated NADP levels which may increase metabolic flux through the pentose phosphate (PPP) pathway, enabling increased nucleotide synthesis, and promoting cell invasion. Inhibition of NADP synthesis rescues the metabolic effects of AOX1 KD. Ectopic AOX1 expression decreases NADP production, PPP flux and nucleotide synthesis, while decreasing invasion in cell line models and suppressing growth in tumor xenografts. Further gain and loss of AOX1 confirm the EZH2-dependent activation, metabolic deregulation, and tumor growth in BLCA. Our findings highlight the therapeutic potential of AOX1 and provide a basis for the development of prognostic markers for advanced BLCA.
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http://dx.doi.org/10.1038/s41388-019-0902-7DOI Listing
October 2020

Leveraging Image-Derived Phenotypic Measurements for Drug-Target Interaction Predictions.

Cancer Inform 2019 12;18:1176935119856595. Epub 2019 Jun 12.

Department of Electrical and Computer Engineering, Rice University, Houston, TX, USA.

In recent years, protein kinases have become some of the most significant drug targets in cancer patients. Kinases are known to regulate the activity of many human proteins, and consequently their inhibition has been used to control cancer proliferation. A significant challenge in drug discovery is the rapid and efficient identification of new small molecules. In this study, we propose a novel in silico drug discovery approach to identify kinase targets that impinge on nuclear receptor signaling with data generated using high-content analysis (HCA). A high-throughput imaging dataset was generated from an siRNA human kinome screen on engineered cells that allow direct visualization of effects on estrogen receptor-α or a chimeric progesterone receptor B binding to specific DNA. Two types of kinase descriptors are extracted from these imaging data: first, a population-median-based descriptor and second a bag-of-words (BoW) descriptor that can capture heterogeneity information in the imaging data. Using these descriptors, we provide prediction results of drug-kinase-target interactions based on single-task learning, multi-task learning, and collaborative filtering methods. The best performing model in target-based drug discovery gives an area under the receiver operating characteristic curve (AUC) of 0.86, whereas the best model in ligand-based discovery gives an AUC of 0.79. These promising results suggest that imaging-based information can be used as an additional source of information to existing virtual screening methods, thereby making the drug discovery process more time and cost efficient.
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http://dx.doi.org/10.1177/1176935119856595DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6563400PMC
June 2019

VCAM1 Is Induced in Ovarian Theca and Stromal Cells in a Mouse Model of Androgen Excess.

Endocrinology 2019 06;160(6):1377-1393

Department of Molecular and Cellular Biology, Baylor College of Medicine, Houston, Texas.

Ovarian theca androgen production is regulated by the pituitary LH and intrafollicular factors. Enhanced androgen biosynthesis by theca cells contributes to polycystic ovary syndrome (PCOS) in women, but the ovarian consequences of elevated androgens are not completely understood. Our study documents the molecular events that are altered in the theca and stromal cells of mice exposed to high androgen levels, using the nonaromatizable androgen DHT. Changes in ovarian morphology and function were observed not only in follicles, but also in the stromal compartment. Genome-wide microarray analyses revealed marked changes in the ovarian transcriptome of DHT-treated females within 1 week. Particularly striking was the increased expression of vascular cell adhesion molecule 1 (Vcam1) specifically in the NR2F2/COUPTF-II lineage theca cells, not granulosa cells, of growing follicles and throughout the stroma of the androgen-treated mice. This response was mediated by androgen receptors (ARs) present in theca and stromal cells. Human theca-derived cultures expressed both ARs and NR2F2 that were nuclear. VCAM1 mRNA and protein were higher in PCOS-derived theca cells compared with control theca and reduced markedly by the AR antagonist flutamide. In the DHT-treated mice, VCAM1 was transiently induced by equine chorionic gonadotropin, when androgen and estrogen biosynthesis peak in preovulatory follicles, and was potently suppressed by a superovulatory dose of human chorionic gonadotropin. High levels of VCAM1 in the theca and interstitial cells of DHT-treated mice and in adult Leydig cells indicate that there may be novel functions for VCAM1 in reproductive tissues, including the gonads.
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http://dx.doi.org/10.1210/en.2018-00731DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6507908PMC
June 2019

Telomere Dysfunction Induces Sirtuin Repression that Drives Telomere-Dependent Disease.

Cell Metab 2019 06 28;29(6):1274-1290.e9. Epub 2019 Mar 28.

Department of Physiology and Biophysics, Baylor College of Medicine, Houston, TX 77030, USA; Huffington Center on Aging, Baylor College of Medicine, Houston, TX 77030, USA. Electronic address:

Telomere shortening is associated with stem cell decline, fibrotic disorders, and premature aging through mechanisms that are incompletely understood. Here, we show that telomere shortening in livers of telomerase knockout mice leads to a p53-dependent repression of all seven sirtuins. P53 regulates non-mitochondrial sirtuins (Sirt1, 2, 6, and 7) post-transcriptionally through microRNAs (miR-34a, 26a, and 145), while the mitochondrial sirtuins (Sirt3, 4, and 5) are regulated in a peroxisome proliferator-activated receptor gamma co-activator 1 alpha-/beta-dependent manner at the transcriptional level. Administration of the NAD(+) precursor nicotinamide mononucleotide maintains telomere length, dampens the DNA damage response and p53, improves mitochondrial function, and, functionally, rescues liver fibrosis in a partially Sirt1-dependent manner. These studies establish sirtuins as downstream targets of dysfunctional telomeres and suggest that increasing Sirt1 activity alone or in combination with other sirtuins stabilizes telomeres and mitigates telomere-dependent disorders.
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http://dx.doi.org/10.1016/j.cmet.2019.03.001DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6657508PMC
June 2019

CARM1 methylates MED12 to regulate its RNA-binding ability.

Life Sci Alliance 2018 Oct 19;1(5):e201800117. Epub 2018 Sep 19.

Department of Epigenetics and Molecular Carcinogenesis, MD Anderson Cancer Center, The University of Texas, Smithville, TX, USA.

The coactivator-associated arginine methyltransferase (CARM1) functions as a regulator of transcription by methylating a diverse array of substrates. To broaden our understanding of CARM1's mechanistic actions, we sought to identify additional substrates for this enzyme. To do this, we generated CARM1 substrate motif antibodies, and used immunoprecipitation coupled with mass spectrometry to identify cellular targets of CARM1, including mediator complex subunit 12 (MED12) and the lysine methyltransferase KMT2D. Both of these proteins are implicated in enhancer function. We identified the major CARM1-mediated MED12 methylation site as arginine 1899 (R), which interacts with the Tudor domain-containing effector molecule, TDRD3. Chromatin immunoprecipitation-seq studies revealed that CARM1 and the methyl mark it deposits are tightly associated with ERα-specific enhancers and positively modulate transcription of estrogen-regulated genes. In addition, we showed that the methylation of MED12, at the R site, and the recruitment of TDRD3 by this methylated motif are critical for the ability of MED12 to interact with activating noncoding RNAs.
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http://dx.doi.org/10.26508/lsa.201800117DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6238599PMC
October 2018

A homing system targets therapeutic T cells to brain cancer.

Nature 2018 09 5;561(7723):331-337. Epub 2018 Sep 5.

Center for Cell and Gene Therapy, Texas Children's Hospital, Houston Methodist Hospital and Baylor College of Medicine, Houston, TX, USA.

Successful T cell immunotherapy for brain cancer requires that the T cells can access tumour tissues, but this has been difficult to achieve. Here we show that, in contrast to inflammatory brain diseases such as multiple sclerosis, where endothelial cells upregulate ICAM1 and VCAM1 to guide the extravasation of pro-inflammatory cells, cancer endothelium downregulates these molecules to evade immune recognition. By contrast, we found that cancer endothelium upregulates activated leukocyte cell adhesion molecule (ALCAM), which allowed us to overcome this immune-evasion mechanism by creating an ALCAM-restricted homing system (HS). We re-engineered the natural ligand of ALCAM, CD6, in a manner that triggers initial anchorage of T cells to ALCAM and conditionally mediates a secondary wave of adhesion by sensitizing T cells to low-level ICAM1 on the cancer endothelium, thereby creating the adhesion forces necessary to capture T cells from the bloodstream. Cytotoxic HS T cells robustly infiltrated brain cancers after intravenous injection and exhibited potent antitumour activity. We have therefore developed a molecule that targets the delivery of T cells to brain cancer.
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http://dx.doi.org/10.1038/s41586-018-0499-yDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6402337PMC
September 2018

Steroid Receptor Coactivator-2 Controls the Pentose Phosphate Pathway through RPIA in Human Endometrial Cancer Cells.

Sci Rep 2018 09 3;8(1):13134. Epub 2018 Sep 3.

Department of Molecular & Cellular Biology, Baylor College of Medicine, Houston, Texas, USA.

Steroid receptor coactivator-2 (SRC-2) is a transcriptional coregulator that modulates the activity of many transcription factors. Levels of SRC-2 are elevated in endometrial biopsies from polycystic ovary syndrome patients, a population predisposed to endometrial cancer (EC). Increased expression of SRC-2 is also detected in neoplastic endometrium suggesting a causal link between elevated SRC-2 expression and the emergence of endometrial disorders that can lead to cancer. Here, we reveal that SRC-2 knockdown reduces EC cell proliferation and anchorage-independence. Additionally, SRC-2 is required to maintain cellular glycolytic capacity and oxidative phosphorylation, processes essential for EC cell proliferation. Importantly, SRC-2 is critical for the normal performance of the pentose phosphate pathway (PPP). Perturbation of the PPP due to loss of SRC-2 expression may result from the depletion of ribose-5-P isomerase (RPIA), a key enzyme of the PPP. As with SRC-2, RPIA knockdown reduces EC cell proliferation, which is accompanied by a decrease in glycolytic capacity and oxidative phosphorylation. Glucose metabolite tracking experiments confirmed that knockdown of SRC-2 and RPIA downregulates the metabolic rate of both glycolysis and the PPP, highlighting a novel regulatory cross-talk between glycolysis and the PPP modulated by SRC-2.
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http://dx.doi.org/10.1038/s41598-018-31372-yDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6120906PMC
September 2018

Combinatorial inhibition of PTPN12-regulated receptors leads to a broadly effective therapeutic strategy in triple-negative breast cancer.

Nat Med 2018 05 26;24(4):505-511. Epub 2018 Mar 26.

Department of Molecular & Human Genetics, Baylor College of Medicine, One Baylor Plaza, Houston, Texas, USA.

Triple-negative breast cancer (TNBC) is an aggressive subtype of breast cancer diagnosed in more than 200,000 women each year and is recalcitrant to targeted therapies. Although TNBCs harbor multiple hyperactive receptor tyrosine kinases (RTKs), RTK inhibitors have been largely ineffective in TNBC patients thus far. We developed a broadly effective therapeutic strategy for TNBC that is based on combined inhibition of receptors that share the negative regulator PTPN12. Previously, we and others identified the tyrosine phosphatase PTPN12 as a tumor suppressor that is frequently inactivated in TNBC. PTPN12 restrains several RTKs, suggesting that PTPN12 deficiency leads to aberrant activation of multiple RTKs and a co-dependency on these receptors. This in turn leads to the therapeutic hypothesis that PTPN12-deficient TNBCs may be responsive to combined RTK inhibition. However, the repertoire of RTKs that are restrained by PTPN12 in human cells has not been systematically explored. By methodically identifying the suite of RTK substrates (MET, PDGFRβ, EGFR, and others) inhibited by PTPN12, we rationalized a combination RTK-inhibitor therapy that induced potent tumor regression across heterogeneous models of TNBC. Orthogonal approaches revealed that PTPN12 was recruited to and inhibited these receptors after ligand stimulation, thereby serving as a feedback mechanism to limit receptor signaling. Cancer-associated mutation of PTPN12 or reduced PTPN12 protein levels diminished this feedback mechanism, leading to aberrant activity of these receptors. Restoring PTPN12 protein levels restrained signaling from RTKs, including PDGFRβ and MET, and impaired TNBC survival. In contrast with single agents, combined inhibitors targeting the PDGFRβ and MET receptors induced the apoptosis in TNBC cells in vitro and in vivo. This therapeutic strategy resulted in tumor regressions in chemo-refractory patient-derived TNBC models. Notably, response correlated with PTPN12 deficiency, suggesting that impaired receptor feedback may establish a combined addiction to these proto-oncogenic receptors. Taken together, our data provide a rationale for combining RTK inhibitors in TNBC and other malignancies that lack receptor-activating mutations.
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http://dx.doi.org/10.1038/nm.4507DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6675908PMC
May 2018

Cisplatin generates oxidative stress which is accompanied by rapid shifts in central carbon metabolism.

Sci Rep 2018 03 9;8(1):4306. Epub 2018 Mar 9.

Bobby R. Alford Department of Otolaryngology Head and Neck Surgery, Baylor College of Medicine, Houston, TX, USA.

Cisplatin is commonly utilized in the treatment of solid tumors. Its mechanism of action is complex and multiple mechanisms of resistance have been described. We sought to determine the impact of cisplatin-generated oxidative stress on head and neck squamous cell carcinoma (HNSCC) proliferation, survival and metabolic activity in order to identify a potential metabolic signature associated with cisplatin response. DNA-bound cisplatin represents a small fraction of total intra-cellular cisplatin but generates a robust oxidative stress response. Neutralization of oxidative stress reverses cisplatin toxicity independent of the mechanism of cell death and TP53 mutational status. Cisplatin-induced oxidative stress triggers rapid shifts in carbon flux in 3 commonly utilized catabolic pathways: glycolysis, pentose phosphate pathway and citric acid cycle. Among these metabolic shifts, decreased flux from pyruvate into lactate is the only metabolic effect consistently observed across multiple HNSCC cell lines of varying genomic backgrounds and may reflect differential cisplatin sensitivity. Oxidative stress is a critical component of cisplatin cytotoxicity in HNSCC and is reflected in acute changes in carbon flux from pyruvate into lactate. This suggests that lactate may contribute to a metabolic signature of acute cisplatin toxicity, and could prove useful in optimizing cisplatin-based treatment regimens in HNSCC.
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http://dx.doi.org/10.1038/s41598-018-22640-yDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5844883PMC
March 2018

Reversible Reaction-Based Fluorescent Probe for Real-Time Imaging of Glutathione Dynamics in Mitochondria.

ACS Sens 2017 Sep 18;2(9):1257-1261. Epub 2017 Aug 18.

Department of Pharmacology and Chemical Biology, ‡Center for Drug Discovery, §Department of Molecular and Cellular Biology, ∥Integrated Microscopy Core, Advanced Technology Cores, ⊥Department of Molecular and Human Genetics, and #Huffington Center on Aging, Baylor College of Medicine , Houston, Texas 77030, United States.

We report a mitochondria-specific glutathione (GSH) probe-designated as Mito-RealThiol (MitoRT)-that can monitor in vivo real-time mitochondrial glutathione dynamics, and apply this probe to follow mitochondrial GSH dynamic changes in living cells for the first time. MitoRT can be utilized in confocal microscopy, super-resolution fluorescence imaging, and flow cytometry systems. Using MitoRT, we demonstrate that cells have a high priority to maintain the GSH level in mitochondria compared to the cytosol not only under normal growing conditions but also upon oxidative stress.
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http://dx.doi.org/10.1021/acssensors.7b00425DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5771714PMC
September 2017

Characterizing properties of non-estrogenic substituted bisphenol analogs using high throughput microscopy and image analysis.

PLoS One 2017 13;12(7):e0180141. Epub 2017 Jul 13.

Molecular and Cellular Biology, Baylor College of Medicine, Houston, Texas, United States of America.

Animal studies have linked the estrogenic properties of bisphenol A (BPA) to adverse effects on the endocrine system. Because of concerns for similar effects in humans, there is a desire to replace BPA in consumer products, and a search for BPA replacements that lack endocrine-disrupting bioactivity is ongoing. We used multiple cell-based models, including an established multi-parametric, high throughput microscopy-based platform that incorporates engineered HeLa cell lines with visible ERα- or ERβ-regulated transcription loci, to discriminate the estrogen-like and androgen-like properties of previously uncharacterized substituted bisphenol derivatives and hydroquinone. As expected, BPA induced 70-80% of the estrogen-like activity via ERα and ERβ compared to E2 in the HeLa prolactin array cell line. 2,2' BPA, Bisguaiacol F, CHDM 4-hydroxybuyl acrylate, hydroquinone, and TM modified variants of BPF showed very limited estrogen-like or androgen-like activity (< 10% of that observed with the control compounds). Interestingly, TM-BFP and CHDM 4-hydroxybuyl acrylate, but not their derivatives, demonstrated evidence of anti-estrogenic and anti-androgenic activity. Our findings indicate that Bisguaiacol F, TM-BFP-ER and TM-BPF-DGE demonstrate low potential for affecting estrogenic or androgenic endocrine activity. This suggest that the tested compounds could be suitable commercially viable alternatives to BPA.
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http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0180141PLOS
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5509144PMC
September 2017

Bone-in-culture array as a platform to model early-stage bone metastases and discover anti-metastasis therapies.

Nat Commun 2017 04 21;8:15045. Epub 2017 Apr 21.

Lester and Sue Smith Breast Center, Baylor College of Medicine, One Baylor Plaza, Houston, Texas 77030, USA.

The majority of breast cancer models for drug discovery are based on orthotopic or subcutaneous tumours. Therapeutic responses of metastases, especially microscopic metastases, are likely to differ from these tumours due to distinct cancer-microenvironment crosstalk in distant organs. Here, to recapitulate such differences, we established an ex vivo bone metastasis model, termed bone-in-culture array or BICA, by fragmenting mouse bones preloaded with breast cancer cells via intra-iliac artery injection. Cancer cells in BICA maintain features of in vivo bone micrometastases regarding the microenvironmental niche, gene expression profile, metastatic growth kinetics and therapeutic responses. Through a proof-of-principle drug screening using BICA, we found that danusertib, an inhibitor of the Aurora kinase family, preferentially inhibits bone micrometastases. In contrast, certain histone methyltransferase inhibitors stimulate metastatic outgrowth of indolent cancer cells, specifically in the bone. Thus, BICA can be used to investigate mechanisms involved in bone colonization and to rapidly test drug efficacies on bone micrometastases.
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http://dx.doi.org/10.1038/ncomms15045DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5413944PMC
April 2017

Mutual regulation of tumour vessel normalization and immunostimulatory reprogramming.

Nature 2017 04 3;544(7649):250-254. Epub 2017 Apr 3.

Lester and Sue Smith Breast Center, Baylor College of Medicine, One Baylor Plaza, Houston, Texas 77030, USA.

Blockade of angiogenesis can retard tumour growth, but may also paradoxically increase metastasis. This paradox may be resolved by vessel normalization, which involves increased pericyte coverage, improved tumour vessel perfusion, reduced vascular permeability, and consequently mitigated hypoxia. Although these processes alter tumour progression, their regulation is poorly understood. Here we show that type 1 T helper (T1) cells play a crucial role in vessel normalization. Bioinformatic analyses revealed that gene expression features related to vessel normalization correlate with immunostimulatory pathways, especially T lymphocyte infiltration or activity. To delineate the causal relationship, we used various mouse models with vessel normalization or T lymphocyte deficiencies. Although disruption of vessel normalization reduced T lymphocyte infiltration as expected, reciprocal depletion or inactivation of CD4 T lymphocytes decreased vessel normalization, indicating a mutually regulatory loop. In addition, activation of CD4 T lymphocytes by immune checkpoint blockade increased vessel normalization. T1 cells that secrete interferon-γ are a major population of cells associated with vessel normalization. Patient-derived xenograft tumours growing in immunodeficient mice exhibited enhanced hypoxia compared to the original tumours in immunocompetent humans, and hypoxia was reduced by adoptive T1 transfer. Our findings elucidate an unexpected role of T1 cells in vasculature and immune reprogramming. T1 cells may be a marker and a determinant of both immune checkpoint blockade and anti-angiogenesis efficacy.
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http://dx.doi.org/10.1038/nature21724DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5788037PMC
April 2017