Monday, April 11, 2011

Hot off the presses! Apr 12 Cancer Cell

The Apr 12 issue of the Cancer Cell is now up on Pubget (About Cancer Cell): if you're at a subscribing institution, just click the link in the latest link at the home page. (Note you'll only be able to get all the PDFs in the issue if your institution subscribes to Pubget.)

Latest Articles Include:

  • The Unholy Trinity: Inflammation, Cytokines, and STAT3 Shape The Cancer Microenvironment
    - Cancer Cells 19(4):429-431 (2011)
    Tumor-associated inflammation is a consequence and a driver of tumorigenesis. Three papers in this issue of Cancer Cell demonstrate the importance of tumor-elicited inflammation in the development and progression of pancreatic ductal adenocarcinoma and esophageal squamous carcinoma. Disruption of tissue homeostasis culminates in activation of STAT3, generating a pro-tumorigenic inflammatory microenvironment.
  • Multiple Effects of Angiopoietin-2 Blockade on Tumors
    - Cancer Cells 19(4):431-433 (2011)
    In this issue of Cancer Cell, Mazzieri, Pucci, and colleagues describe the marked effects of inhibiting the proangiogenic cytokine, Angiopoietin-2, on tumor angiogenesis and progression in spontaneous tumor models, as well as the proangiogenic functions of TIE2-expressing macrophages.
  • Chemokines and Cancer: A Fatal Attraction
    - Cancer Cells 19(4):434-435 (2011)
    Chemokines are important components of cancer-related inflammation. In this issue of Cancer Cell, Chen et al. report that the chemokine CCL18, produced by tumor-associated macrophages, promotes malignant behavior and correlates with metastasis in human breast cancer. Unexpectedly, PITPNM3/Nir1, a molecule unrelated to chemokine receptors, was identified as its elusive receptor.
  • Unswitch-ABL Drugs Overcome Resistance in Chronic Myeloid Leukemia
    - Cancer Cells 19(4):435-437 (2011)
    ABL inhibitors have revolutionized the clinical management of chronic myeloid leukemia, but the BCR-ABLT315I mutation confers resistance to currently approved drugs. Chan et al. show, in this issue of Cancer Cell, that "switch-control" inhibitors block BCR-ABLT315I activity by preventing ABL from switching from the inactive to active conformation.
  • Resisting Targeted Therapy: Fifty Ways to Leave Your EGFR
    - Cancer Cells 19(4):437-440 (2011)
    Despite the promise of the new generation of molecularly targeted drugs, intrinsic and acquired resistance is proving to be as problematic as with cytotoxic drugs. Two recent papers have identified novel ways by which non-small cell lung cancers can exhibit resistance to EGFR inhibitors and suggest new therapeutic workarounds.
  • Stat3 and MMP7 Contribute to Pancreatic Ductal Adenocarcinoma Initiation and Progression
    - Cancer Cells 19(4):441-455 (2011)
    Chronic pancreatitis is a well-known risk factor for pancreatic ductal adenocarcinoma (PDA) development in humans, and inflammation promotes PDA initiation and progression in mouse models of the disease. However, the mechanistic link between inflammatory damage and PDA initiation is unclear. Using a Kras-driven mouse model of PDA, we establish that the inflammatory mediator Stat3 is a critical component of spontaneous and pancreatitis-accelerated PDA precursor formation and supports cell proliferation, metaplasia-associated inflammation, and MMP7 expression during neoplastic development. Furthermore, we show that Stat3 signaling enforces MMP7 expression in PDA cells and that MMP7 deletion limits tumor size and metastasis in mice. Finally, we demonstrate that serum MMP7 level in human patients with PDA correlated with metastatic disease and survival.
  • Stat3/Socs3 Activation by IL-6 Transsignaling Promotes Progression of Pancreatic Intraepithelial Neoplasia and Development of Pancreatic Cancer
    - Cancer Cells 19(4):456-469 (2011)
    Physiological levels of KrasG12D are sufficient to induce pancreatic intraepithelial neoplasias (PanINs); the mechanisms that drive PanIN progression are unknown. Here, we establish that, in addition to oncogenic KrasG12D, IL-6 transsignaling-dependent activation of Stat3/Socs3 is required to promote PanIN progression and pancreatic ductal adenocarcinoma (PDAC). Myeloid compartment induces Stat3 activation by secreting IL-6; consequently, IL-6 transsignaling activates Stat3 in the pancreas. Using genetic tools, we show that inactivation of IL-6 transsignaling or Stat3 inhibits PanIN progression and reduces the development of PDAC. Aberrant activation of Stat3 through homozygous deletion of Socs3 in the pancreas accelerates PanIN progression and PDAC development. Our data describe the involvement of IL-6 transsignaling/Stat3/Socs3 in PanIN progression and PDAC development.
  • Deletion of p120-Catenin Results in a Tumor Microenvironment with Inflammation and Cancer that Establishes It as a Tumor Suppressor Gene
    - Cancer Cells 19(4):470-483 (2011)
    p120-catenin (p120ctn) interacts with E-cadherin, but to our knowledge, no formal proof that p120ctn functions as a bona fide tumor suppressor gene has emerged to date. We report herein that p120ctn loss leads to tumor development in mice. We have generated a conditional knockout model of p120ctn whereby mice develop preneoplastic and neoplastic lesions in the oral cavity, esophagus, and squamous forestomach. Tumor-derived cells secrete granulocyte macrophage colony-stimulating factor (GM-CSF), macrophage colony-stimulating factor (M-CSF), monocyte chemotactic protein-1 (MCP-1), and tumor necrosis factor-α (TNFα). The tumors contain significant desmoplasia and immune cell infiltration. Immature myeloid cells comprise a significant percentage of the immune cells present and likely participate in fostering a favorable tumor microenvironment, including the activation of fibroblasts.
  • Integrated Transcript and Genome Analyses Reveal NKX2-1 and MEF2C as Potential Oncogenes in T Cell Acute Lymphoblastic Leukemia
    - Cancer Cells 19(4):484-497 (2011)
    To identify oncogenic pathways in T cell acute lymphoblastic leukemia (T-ALL), we combined expression profiling of 117 pediatric patient samples and detailed molecular-cytogenetic analyses including the Chromosome Conformation Capture on Chip (4C) method. Two T-ALL subtypes were identified that lacked rearrangements of known oncogenes. One subtype associated with cortical arrest, expression of cell cycle genes, and ectopic NKX2-1 or NKX2-2 expression for which rearrangements were identified. The second subtype associated with immature T cell development and high expression of the MEF2C transcription factor as consequence of rearrangements of MEF2C, transcription factors that target MEF2C, or MEF2C-associated cofactors. We propose NKX2-1, NKX2-2, and MEF2C as T-ALL oncogenes that are activated by various rearrangements.
  • Nonreceptor Tyrosine Kinase BMX Maintains Self-Renewal and Tumorigenic Potential of Glioblastoma Stem Cells by Activating STAT3
    - Cancer Cells 19(4):498-511 (2011)
    Glioblastomas display cellular hierarchies containing tumor-propagating glioblastoma stem cells (GSCs). STAT3 is a critical signaling node in GSC maintenance but molecular mechanisms underlying STAT3 activation in GSCs are poorly defined. Here we demonstrate that the bone marrow X-linked (BMX) nonreceptor tyrosine kinase activates STAT3 signaling to maintain self-renewal and tumorigenic potential of GSCs. BMX is differentially expressed in GSCs relative to nonstem cancer cells and neural progenitors. BMX knockdown potently inhibited STAT3 activation, expression of GSC transcription factors, and growth of GSC-derived intracranial tumors. Constitutively active STAT3 rescued the effects of BMX downregulation, supporting that BMX signals through STAT3 in GSCs. These data demonstrate that BMX represents a GSC therapeutic target and reinforces the importance of STAT3 signaling in stem-like cancer phenotypes.
  • Targeting the ANG2/TIE2 Axis Inhibits Tumor Growth and Metastasis by Impairing Angiogenesis and Disabling Rebounds of Proangiogenic Myeloid Cells
    - Cancer Cells 19(4):512-526 (2011)
    Tumor-infiltrating myeloid cells convey proangiogenic programs that counteract the efficacy of antiangiogenic therapy. Here, we show that blocking angiopoietin-2 (ANG2), a TIE2 ligand and angiogenic factor expressed by activated endothelial cells (ECs), regresses the tumor vasculature and inhibits progression of late-stage, metastatic MMTV-PyMT mammary carcinomas and RIP1-Tag2 pancreatic insulinomas. ANG2 blockade did not inhibit recruitment of MRC1+ TIE2-expressing macrophages (TEMs) but impeded their upregulation of Tie2, association with blood vessels, and ability to restore angiogenesis in tumors. Conditional Tie2 gene knockdown in TEMs was sufficient to decrease tumor angiogenesis. Our findings support a model wherein the ANG2-TIE2 axis mediates cell-to-cell interactions between TEMs and ECs that are important for tumor angiogenesis and can be targeted to induce effective antitumor responses.
  • A Tight Junction-Associated Merlin-Angiomotin Complex Mediates Merlin's Regulation of Mitogenic Signaling and Tumor Suppressive Functions
    - Cancer Cells 19(4):527-540 (2011)
    The Merlin/NF2 tumor suppressor restrains cell growth and tumorigenesis by controlling contact-dependent inhibition of proliferation. We have identified a tight-junction-associated protein complex comprising Merlin, Angiomotin, Patj, and Pals1. We demonstrate that Angiomotin functions downstream of Merlin and upstream of Rich1, a small GTPase Activating Protein, as a positive regulator of Rac1. Merlin, through competitive binding to Angiomotin, releases Rich1 from the Angiomotin-inhibitory complex, allowing Rich1 to inactivate Rac1, ultimately leading to attenuation of Rac1 and Ras-MAPK pathways. Patient-derived Merlin mutants show diminished binding capacities to Angiomotin and are unable to dissociate Rich1 from Angiomotin or inhibit MAPK signaling. Depletion of Angiomotin in Nf2−/− Schwann cells attenuates the Ras-MAPK signaling pathway, impedes cellular proliferation in vitro and tumorigenesis in vivo.
  • CCL18 from Tumor-Associated Macrophages Promotes Breast Cancer Metastasis via PITPNM3
    - Cancer Cells 19(4):541-555 (2011)
    Tumor-associated macrophages (TAMs) can influence cancer progression and metastasis, but the mechanism remains unclear. Here, we show that breast TAMs abundantly produce CCL18, and its expression in blood or cancer stroma is associated with metastasis and reduced patient survival. CCL18 released by breast TAMs promotes the invasiveness of cancer cells by triggering integrin clustering and enhancing their adherence to extracellular matrix. Furthermore, we identify PITPNM3 as a functional receptor for CCL18 that mediates CCL18 effect and activates intracellular calcium signaling. CCL18 promotes the invasion and metastasis of breast cancer xenografts, whereas suppressing PITPNM3 abrogates these effects. These findings indicate that CCL18 derived from TAMs plays a critical role in promoting breast cancer metastasis via its receptor, PITPNM3.
  • Conformational Control Inhibition of the BCR-ABL1 Tyrosine Kinase, Including the Gatekeeper T315I Mutant, by the Switch-Control Inhibitor DCC-2036
    - Cancer Cells 19(4):556-568 (2011)
    Acquired resistance to ABL1 tyrosine kinase inhibitors (TKIs) through ABL1 kinase domain mutations, particularly the gatekeeper mutant T315I, is a significant problem for patients with chronic myeloid leukemia (CML). Using structure-based drug design, we developed compounds that bind to residues (Arg386/Glu282) ABL1 uses to switch between inactive and active conformations. The lead "switch-control" inhibitor, DCC-2036, potently inhibits both unphosphorylated and phosphorylated ABL1 by inducing a type II inactive conformation, and retains efficacy against the majority of clinically relevant CML-resistance mutants, including T315I. DCC-2036 inhibits BCR-ABL1T315I-expressing cell lines, prolongs survival in mouse models of T315I mutant CML and B-lymphoblastic leukemia, and inhibits primary patient leukemia cells expressing T315I in vitro and in vivo, supporting its clinical development in TKI-resistant Ph+ leukemia.

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