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Ting, David

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Ting

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Ting, David
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Now showing 1 - 10 of 11
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    Single-Cell RNA Sequencing Identifies Extracellular Matrix Gene Expression by Pancreatic Circulating Tumor Cells
    (2014) Ting, David; Wittner, Ben; Ligorio, Matteo; Jordan, Nicole Vincent; Shah, Ajay M.; Miyamoto, David; Aceto, Nicola; Bersani, Francesca; Brannigan, Brian W.; Xega, Kristina; Ciciliano, Jordan C.; Zhu, Huili; MacKenzie, Olivia C.; Trautwein, Julie; Arora, Kshitij S.; Shahid, Mohammad; Ellis, Haley L.; Qu, Na; Bardeesy, Nabeel; Rivera, Miguel; Deshpande, Vikram; Ferrone, Cristina; Kapur, Ravi; Ramaswamy, Sridhar; Shioda, Toshi; Toner, Mehmet; Maheswaran, Shyamala; Haber, Daniel
    SUMMARY Circulating tumor cells (CTCs) are shed from primary tumors into the bloodstream, mediating the hematogenous spread of cancer to distant organs. To define their composition, we compared genome-wide expression profiles of CTCs with matched primary tumors in a mouse model of pancreatic cancer, isolating individual CTCs using epitope-independent microfluidic capture, followed by single-cell RNA sequencing. CTCs clustered separately from primary tumors and tumor-derived cell lines, showing low-proliferative signatures, enrichment for the stem-cell-associated gene Aldh1a2, biphenotypic expression of epithelial and mesenchymal markers, and expression of Igfbp5, a gene transcript enriched at the epithelial-stromal interface. Mouse as well as human pancreatic CTCs exhibit a very high expression of stromal-derived extracellular matrix (ECM) proteins, including SPARC, whose knockdown in cancer cells suppresses cell migration and invasiveness. The aberrant expression by CTCs of stromal ECM genes points to their contribution of microenvironmental signals for the spread of cancer to distant organs.
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    HER2 expression identifies dynamic functional states within circulating breast cancer cells
    (2016) Jordan, Nicole Vincent; Bardia, Aditya; Wittner, Ben; Benes, Cyril; Ligorio, Matteo; Zheng, Yu; Yu, Min; Sundaresan, Tilak K.; Licausi, Joseph A.; Desai, Rushil; O’Keefe, Ryan M.; Ebright, Richard; Boukhali, Myriam; Sil, Srinjoy; Onozato, Maristela Lika; Iafrate, Anthony; Kapur, Ravi; Sgroi, Dennis; Ting, David; Toner, Mehmet; Ramaswamy, Sridhar; Haas, Wilhelm; Maheswaran, Shyamala; Haber, Daniel
    Circulating tumor cells (CTCs) in women with advanced estrogen receptor-positive/HER2-negative breast cancer acquire a HER2-positive subpopulation following multiple courses of therapy1,2. In contrast to HER2-amplified primary breast cancer, which is highly sensitive to HER2-targeted therapy, the clinical significance of acquired HER2 heterogeneity during the evolution of metastatic breast cancer is unknown. Here, we analyzed CTCs from 19 ER+/HER2− patients, 84% of whom had acquired CTCs expressing HER2. Cultured CTCs maintain discrete HER2+ and HER2− subpopulations: HER2+ CTCs are more proliferative but not addicted to HER2, consistent with activation of multiple signaling pathways. HER2− CTCs show activation of Notch and DNA damage pathways, exhibiting resistance to cytotoxic chemotherapy, but sensitivity to Notch inhibition. HER2+ and HER2− CTCs interconvert spontaneously, with cells of one phenotype producing daughters of the opposite within four cell doublings. While HER2+ and HER2− CTCs have comparable tumor initiating potential, differential proliferation favors the HER2+ state, while oxidative stress or cytotoxic chemotherapy enhances transition to the HER2− phenotype. Simultaneous treatment with paclitaxel and Notch inhibitors achieves sustained suppression of tumorigenesis in orthotopic CTC-derived tumor models. Together, these results point to distinct yet interconverting phenotypes within patient-derived CTCs, contributing to progression of breast cancer and acquisition of drug resistance.
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    Global Cancer Transcriptome Quantifies Repeat Element Polarization between Immunotherapy Responsive and T Cell Suppressive Classes
    (2018) Solovyov, Alexander; Vabret, Nicolas; Arora, Kshitij S.; Snyder, Alexandra; Funt, Samuel A.; Bajorin, Dean F.; Rosenberg, Jonathan E.; Bhardwaj, Nina; Ting, David; Greenbaum, Benjamin D.
    SUMMARY It has been posited that anti-tumoral innate activation is driven by derepression of endogenous repeats. We compared RNA sequencing protocols to assess repeat transcriptomes in The Cancer Genome Atlas (TCGA). Although poly(A) selection efficiently detects coding genes, most non-coding genes, and limited subsets of repeats, it fails to capture overall repeat expression and co-expression. Alternatively, total RNA expression reveals distinct repeat co-expression subgroups and delivers greater dynamic changes, implying they may serve as better biomarkers of clinical outcomes. We show that endogenous retrovirus expression predicts immunotherapy response better than conventional immune signatures in one cohort yet is not predictive in another. Moreover, we find that global repeat derepression, including the HSATII satellite repeat, correlates with an immunosuppressive phenotype in colorectal and pancreatic tumors and validate in situ. In conclusion, we stress the importance of analyzing the full spectrum of repeat transcription to decode their role in tumor immunity.
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    Dynamic Chromatin Modification Sustains Epithelial-Mesenchymal Transition following Inducible Expression of Snail-1
    (2014) Javaid, Sarah; Zhang, Jianmin; Anderssen, Endre; Black, Josh C.; Wittner, Ben; Tajima, Ken; Ting, David; Smolen, Gromoslaw A.; Zubrowski, Matthew; Desai, Rushil; Maheswaran, Shyamala; Ramaswamy, Sridhar; Whetstine, Johnathan; Haber, Daniel
    SUMMARY Epithelial-mesenchymal transition (EMT) is thought to contribute to cancer metastasis, but its underlying mechanisms are not well understood. To define early steps in this cellular transformation, we analyzed human mammary epithelial cells with tightly regulated expression of Snail-1, a master regulator of EMT. After Snail-1 induction, epithelial markers were repressed within 6 hr, and mesenchymal genes were induced at 24 hr. Snail-1 binding to its target promoters was transient (6–48 hr) despite continued protein expression, and it was followed by both transient and long-lasting chromatin changes. Pharmacological inhibition of selected histone acetylation and demethylation pathways suppressed the induction as well as the maintenance of Snail-1-mediated EMT. Thus, EMT involves an epigenetic switch that may be prevented or reversed with the use of small-molecule inhibitors of chromatin modifiers.
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    BRCA1 haploinsufficiency for replication stress suppression in primary cells
    (Nature Pub. Group, 2014) Pathania, Shailja; Bade, Sangeeta; Le Guillou, Morwenna; Burke, Karly; Reed, Rachel; Bowman-Colin, Christian; Su, Ying; Ting, David; Polyak, Kornelia; Richardson, Andrea; Feunteun, Jean; Garber, Judy; Livingston, David
    BRCA1—a breast and ovarian cancer suppressor gene—promotes genome integrity. To study the functionality of BRCA1 in the heterozygous state, we established a collection of primary human BRCA1+/+ and BRCA1mut/+ mammary epithelial cells and fibroblasts. Here we report that all BRCA1mut/+ cells exhibited multiple normal BRCA1 functions, including the support of homologous recombination- type double-strand break repair (HR-DSBR), checkpoint functions, centrosome number control, spindle pole formation, Slug expression and satellite RNA suppression. In contrast, the same cells were defective in stalled replication fork repair and/or suppression of fork collapse, that is, replication stress. These defects were rescued by reconstituting BRCA1mut/+ cells with wt BRCA1. In addition, we observed ‘conditional’ haploinsufficiency for HR-DSBR in BRCA1mut/+ cells in the face of replication stress. Given the importance of replication stress in epithelial cancer development and of an HR defect in breast cancer pathogenesis, both defects are candidate contributors to tumorigenesis in BRCA1-deficient mammary tissue.
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    A microfluidic device for label-free, physical capture of circulating tumor cell-clusters
    (2015) Sarioglu, A. Fatih; Aceto, Nicola; Kojic, Nikola; Donaldson, Maria C.; Zeinali, Mahnaz; Hamza, Bashar; Engstrom, Amanda; Zhu, Huili; Sundaresan, Tilak K.; Miyamoto, David; Luo, Xi; Bardia, Aditya; Wittner, Ben; Ramaswamy, Sridhar; Shioda, Toshi; Ting, David; Stott, Shannon; Kapur, Ravi; Maheswaran, Shyamala; Haber, Daniel; Toner, Mehmet
    Cancer cells metastasize through the bloodstream either as single migratory circulating tumor cells (CTCs) or as multicellular groupings (CTC-clusters). Existing technologies for CTC enrichment are designed primarily to isolate single CTCs, and while CTC-clusters are detectable in some cases, their true prevalence and significance remain to be determined. Here, we developed a microchip technology (Cluster-Chip) specifically designed to capture CTC-clusters independent of tumor-specific markers from unprocessed blood. CTC-clusters are isolated through specialized bifurcating traps under low shear-stress conditions that preserve their integrity and even two-cell clusters are captured efficiently. Using the Cluster-Chip, we identify CTC-clusters in 30–40% of patients with metastatic cancers of the breast, prostate and melanoma. RNA sequencing of CTC-clusters confirms their tumor origin and identifies leukocytes within the clusters as tissue-derived macrophages. Together, the development of a device for efficient capture of CTC-clusters will enable detailed characterization of their biological properties and role in cancer metastasis.
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    Expression of β-globin by cancer cells promotes cell survival during blood-borne dissemination
    (Nature Publishing Group, 2017) Zheng, Yu; Miyamoto, David; Wittner, Ben; Sullivan, James; Aceto, Nicola; Jordan, Nicole Vincent; Yu, Min; Karabacak, Nezihi; Comaills, Valentine; Morris, Robert; Desai, Rushil; Desai, Niyati; Emmons, Erin; Milner, John D.; Lee, Richard; Wu, Chin-Lee; Sequist, Lecia; Haas, Wilhelm; Ting, David; Toner, Mehmet; Ramaswamy, Sridhar; Maheswaran, Shyamala; Haber, Daniel
    Metastasis-competent circulating tumour cells (CTCs) experience oxidative stress in the bloodstream, but their survival mechanisms are not well defined. Here, comparing single-cell RNA-Seq profiles of CTCs from breast, prostate and lung cancers, we observe consistent induction of β-globin (HBB), but not its partner α-globin (HBA). The tumour-specific origin of HBB is confirmed by sequence polymorphisms within human xenograft-derived CTCs in mouse models. Increased intracellular reactive oxygen species (ROS) in cultured breast CTCs triggers HBB induction, mediated through the transcriptional regulator KLF4. Depletion of HBB in CTC-derived cultures has minimal effects on primary tumour growth, but it greatly increases apoptosis following ROS exposure, and dramatically reduces CTC-derived lung metastases. These effects are reversed by the anti-oxidant N-Acetyl Cysteine. Conversely, overexpression of HBB is sufficient to suppress intracellular ROS within CTCs. Altogether, these observations suggest that β-globin is selectively deregulated in cancer cells, mediating a cytoprotective effect during blood-borne metastasis.
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    P53 and the defenses against genome instability caused by transposons and repetitive elements
    (John Wiley and Sons Inc., 2016) Levine, Arnold J.; Ting, David; Greenbaum, Benjamin D.
    The recent publication by Wylie et al. is reviewed, demonstrating that the p53 protein regulates the movement of transposons. While this work presents genetic evidence for a piRNA‐mediated p53 interaction with transposons in Drosophila and zebrafish, it is herein placed in the context of a decade or so of additional work that demonstrated a role for p53 in regulating transposons and other repetitive elements. The line of thought in those studies began with the observation that transposons damage DNA and p53 regulates DNA damage. The presence of transposon movement can increase the rate of evolution in the germ line and alter genes involved in signal transduction pathways. Transposition can also play an important role in cancers where the p53 gene function is often mutated. This is particularly interesting as recent work has shown that de‐repression of repetitive elements in cancer has important consequences for the immune system and tumor microenvironment.
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    RNA Sequencing of Pancreatic Circulating Tumour Cells Implicates WNT Signaling in Metastasis
    (2012) Yu, Min; Ting, David; Stott, Shannon; Wittner, Ben; Ozsolak, Fatih; Paul, S.; Ciciliano, Jordan C.; Smas, Malgorzata E.; Winokur, Daniel; Gilman, Anna J.; Ulman, Matthew J.; Xega, Kristina; Contino, Gianmarco; Alagesan, Brinda; Brannigan, Brian W.; Milos, Patrice M.; Ryan, David; Sequist, Lecia; Bardeesy, Nabeel; Ramaswamy, Sridhar; Toner, Mehmet; Maheswaran, Shyamala; Haber, Daniel
    Circulating tumour cells (CTCs) shed into blood from primary cancers include putative precursors that initiate distal metastases. While these cells are extraordinarily rare, they may identify cellular pathways contributing to the blood-borne dissemination of cancer. Here, we adapted a microfluidic device for efficient capture of CTCs from an endogenous mouse pancreatic cancer model and subjected CTCs to single molecule RNA sequencing, identifying Wnt2 as a candidate gene enriched in CTCs. Expression of Wnt2 in pancreatic cancer cells suppresses anoikis, enhances anchorage-independent sphere formation, and increases metastatic propensity in vivo. This effect is correlated with fibronectin upregulation and suppressed by inhibition of Map3k7 (Tak1) kinase. In humans, formation of non-adherent tumour spheres by pancreatic cancer cells is associated with upregulation of multiple Wnt genes, and pancreatic CTCs revealed enrichment for Wnt signaling in 5 of 11 cases. Thus, molecular analysis of CTCs may identify candidate therapeutic targets to prevent the distal spread of cancer.
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    STK38L kinase ablation promotes loss of cell viability in a subset of KRAS-dependent pancreatic cancer cell lines
    (Impact Journals LLC, 2017) Grant, Trevor J.; Mehta, Anita K.; Gupta, Anamika; Sharif, Ahmad A.D.; Arora, Kshitij S.; Deshpande, Vikram; Ting, David; Bardeesy, Nabeel; Ganem, Neil J.; Hergovich, Alexander; Singh, Anurag
    Pancreatic ductal adenocarcinomas (PDACs) are highly aggressive malignancies, associated with poor clinical prognosis and limited therapeutic options. Oncogenic KRAS mutations are found in over 90% of PDACs, playing a central role in tumor progression. Global gene expression profiling of PDAC reveals 3-4 major molecular subtypes with distinct phenotypic traits and pharmacological vulnerabilities, including variations in oncogenic KRAS pathway dependencies. PDAC cell lines of the aberrantly differentiated endocrine exocrine (ADEX) subtype are robustly KRAS-dependent for survival. The KRAS gene is located on chromosome 12p11-12p12, a region amplified in 5-10% of primary PDACs. Within this amplicon, we identified co-amplification of KRAS with the STK38L gene in a subset of primary human PDACs and PDAC cell lines. Therefore, we determined whether PDAC cell lines are dependent on STK38L expression for proliferation and viability. STK38L encodes a serine/threonine kinase, which shares homology with Hippo pathway kinases LATS1/2. We show that STK38L expression is elevated in a subset of primary PDACs and PDAC cell lines displaying ADEX subtype characteristics, including overexpression of mutant KRAS. RNAi-mediated depletion of STK38L in a subset of ADEX subtype cell lines inhibits cellular proliferation and induces apoptosis. Concomitant with these effects, STK38L depletion causes increased expression of the LATS2 kinase and the cell cycle regulator p21. LATS2 depletion partially rescues the cytostatic and cytotoxic effects of STK38L depletion. Lastly, high STK38L mRNA expression is associated with decreased overall patient survival in PDACs. Collectively, our findings implicate STK38L as a candidate targetable vulnerability in a subset of molecularly-defined PDACs.