Runx1 is associated with breast cancer progression in MMTV-PyMT transgenic mice and its depletion in vitro inhibits migration and invasion
Runx1 is a transcription factor essential for definitive hematopoiesis, and genetic abnormalities in Runx1 cause leukemia. Runx1 is functionally promiscuous and acts as either an oncogene or tumor suppressor gene in certain epithelial cancers. Recent evidence suggests that Runx1 is an important factor in breast cancer, however its role remains ambiguous. Here, we addressed whether Runx1 has a specific pathological role during breast cancer progression and show that Runx1 has an oncogenic function. We observed elevated Runx1 expression in a subset of human breast cancers. Furthermore, throughout the course of disease progression in a classical mouse model of breast cancer (i.e., the MMTV-PyMT transgenic model), Runx1 expression increases in the primary site (mammary gland) and is further upregulated in tumors and distal lung metastatic lesions. Ex vivo studies using tumor epithelial cells derived from these mice express significantly higher levels of Runx1 than normal mammary epithelial cells. The tumor cells exhibit increased rates of migration and invasion, indicative of an aggressive cancer phenotype. Inhibition of Runx1 expression using RNA interference significantly abrogates these cancer-relevant phenotypic characteristics. Importantly, our data establish that Runx1 contributes to murine mammary tumor development and malignancy and potentially represents a key disease-promoting and prognostic factor in human breast cancer progression and metastasis. This article is protected by copyright. All rights reserved.
The role of ERbeta in prostate cancer is unclear, although loss of ERbeta is associated with aggressive disease. Given that mice deficient in ERbeta do not develop prostate cancer, we hypothesized that ERbeta loss occurs as a consequence of tumorigenesis caused by other oncogenic mechanisms and that its loss is necessary for tumorigenesis. In support of this hypothesis, we found that ERbeta is targeted for repression in prostate cancer caused by PTEN deletion and that loss of ERbeta is important for tumor formation. ERbeta transcription is repressed by BMI-1, which is induced by PTEN deletion and important for prostate tumorigenesis. This finding provides a mechanism for how ERbeta expression is regulated in prostate cancer. Repression of ERbeta contributes to tumorigenesis because it enables HIF-1/VEGF signaling that sustains BMI-1 expression. These data reveal a positive feedback loop that is activated in response to PTEN loss and sustains BMI-1.
Autophagy plays a key role in the maintenance of cellular homeostasis. In healthy cells, such a homeostatic activity constitutes a robust barrier against malignant transformation. Accordingly, many oncoproteins inhibit, and several oncosuppressor proteins promote, autophagy. Moreover, autophagy is required for optimal anticancer immunosurveillance. In neoplastic cells, however, autophagic responses constitute a means to cope with intracellular and environmental stress, thus favoring tumor progression. This implies that at least in some cases, oncogenesis proceeds along with a temporary inhibition of autophagy or a gain of molecular functions that antagonize its oncosuppressive activity. Here, we discuss the differential impact of autophagy on distinct phases of tumorigenesis and the implications of this concept for the use of autophagy modulators in cancer therapy.
Aldehyde Dehydrogenase Is Regulated by beta-Catenin/TCF and Promotes Radioresistance in Prostate Cancer Progenitor Cells
Radiotherapy is a curative treatment option in prostate cancer. Nevertheless, patients with high-risk prostate cancer are prone to relapse. Identification of the predictive biomarkers and molecular mechanisms of radioresistance bears promise to improve cancer therapies. In this study, we show that aldehyde dehydrogenase (ALDH) activity is indicative of radioresistant prostate progenitor cells with an enhanced DNA repair capacity and activation of epithelial-mesenchymal transition (EMT). Gene expression profiling of prostate cancer cells, their radioresistant derivatives, ALDH(+) and ALDH(-) cell populations revealed the mechanisms, which link tumor progenitors to radioresistance, including activation of the WNT/beta-catenin signaling pathway. We found that expression of the ALDH1A1 gene is regulated by the WNT signaling pathway and co-occurs with expression of beta-catenin in prostate tumor specimens. Inhibition of the WNT pathway led to a decrease in ALDH(+) tumor progenitor population and to radiosensitization of cancer cells. Taken together, our results indicate that ALDH(+) cells contribute to tumor radioresistance and their molecular targeting may enhance the effectiveness of radiotherapy. Cancer Res; 75(7); 1482-94. (c)2015 AACR.
Autophagy delivers cytoplasmic material to lysosomes for degradation. First identified in yeast, the core genes that control this process are conserved in higher organisms. Studies of mammalian cell cultures have expanded our understanding of the core autophagy pathway, but cannot reveal the unique animal-specific mechanisms for the regulation and function of autophagy. Multicellular organisms have different types of cells that possess distinct composition, morphology, and organization of intracellular organelles. In addition, the autophagic machinery integrates signals from other cells and environmental conditions to maintain cell, tissue and organism homeostasis. Here, we highlight how studies of autophagy in flies and worms have identified novel core autophagy genes and mechanisms, and provided insight into the context-specific regulation and function of autophagy.
Vascular endothelial growth factor C (VEGF-C) is a potent lymphangiogenic cytokine that signals via the coordinated action of two cell surface receptors, Neuropilin-2 (Nrp2) and VEGFR-3. Diseases associated with both loss and gain of VEGF-C function, lymphedema and cancer, respectively, motivate studies of VEGF-C/Nrp2 binding and inhibition. Here, we demonstrate that VEGF-C binding to Nrp2 is regulated by C-terminal proteolytic maturation. The structure of the VEGF-C C terminus in complex with the ligand binding domains of Nrp2 demonstrates that a cryptic Nrp2 binding motif is released upon proteolysis, allowing specific engagement with the b1 domain of Nrp2. Based on the identified structural requirements for Nrp2 binding to VEGF-C, we hypothesized that the endogenous secreted splice form of Nrp2, s9Nrp2, may function as a selective inhibitor of VEGF-C. We find that s9Nrp2 forms a stable dimer that potently inhibits VEGF-C/Nrp2 binding and cellular signaling. These data provide critical insight into VEGF-C/Nrp2 binding and inhibition.
This is the May 2015 issue of the UMass Center for Clinical and Translational Science Newsletter containing news and events of interest.
Cytoplasmic Polyadenylation Element Binding (CPEB) proteins are translational regulators that can either activate or repress translation depending on the target mRNA and the specific biological context. There are two CPEB subfamilies and most animals have one or more genes from each. Drosophila has a single CPEB gene, orb and orb2, from each subfamily. orb expression is only detected at high levels in the germline and has critical functions in oogenesis but not spermatogenesis. By contrast, orb2 is broadly expressed in the soma; and previous studies have revealed important functions in asymmetric cell division, viability, motor function, learning, and memory. Here we show that orb2 is also expressed in the adult male germline and that it has essential functions in programming the progression of spermatogenesis from meiosis through differentiation. Like the translational regulators boule (bol) and off-schedule (ofs), orb2 is required for meiosis and orb2 mutant spermatocytes undergo a prolonged arrest during the meiotic G2-M transition. However, orb2 differs from boule and off-schedule in that this arrest occurs at a later step in meiotic progression after the synthesis of the meiotic regulator twine. orb2 is also required for the orderly differentiation of the spermatids after meiosis is complete. The differentiation defects in orb2 mutants include abnormal elongation of the spermatid flagellar axonemes, a failure in individualization and improper post-meiotic gene expression. Amongst the orb2 differentiation targets are orb and two other mRNAs, which are transcribed post-meiotically and localized to the tip of the flagellar axonemes. Additionally, analysis of a partial loss of function orb2 mutant suggests that the orb2 differentiation phenotypes are independent of the earlier arrest in meiosis.
The 61 CTSA Consortium sites are home to valuable programs and infrastructure supporting translational science and all are charged with ensuring that such investments translate quickly to improved clinical care. Catalog of Assets for Translational and Clinical Health Research (CATCHR) is the Consortium's effort to collect and make available information on programs and resources to maximize efficiency and facilitate collaborations. By capturing information on a broad range of assets supporting the entire clinical and translational research spectrum, CATCHR aims to provide the necessary infrastructure and processes to establish and maintain an open-access, searchable database of consortium resources to support multisite clinical and translational research studies. Data are collected using rigorous, defined methods, with the resulting information made visible through an integrated, searchable Web-based tool. Additional easy-to-use Web tools assist resource owners in validating and updating resource information over time. In this paper, we discuss the design and scope of the project, data collection methods, current results, and future plans for development and sustainability. With increasing pressure on research programs to avoid redundancy, CATCHR aims to make available information on programs and core facilities to maximize efficient use of resources.
Academic medical product development: an emerging alliance of technology transfer organizations and the CTSA
To bring the benefits of science more quickly to patient care, the NIH National Center Advancing Translational Sciences (NCATS) supports programs that enhance the development, testing, and implementation of new medical products and procedures. The NCATS clinical and translational science award (CTSA) program is central to that mission; creating an academic home for clinical and translational science and supporting those involved in the discovery and development of new health-related inventions. The technology transfer Offices (TTO) of CTSA-funded universities can be important partners in the development process; facilitating the transfer of medical research to the commercial sector for further development and ultimately, distribution to patients. The Aggregating Intellectual Property (IP) Working Group (AWG) of the CTSA public private partnerships key function committee (PPP-KFC) developed a survey to explore how CTSA-funded institutions currently interface with their respective TTOs to support medical product development. The results suggest a range of relationships across institutions; approximately half have formal collaborative programs, but only a few have well-connected programs. Models of collaborations are described and provided as examples of successful CTSA/TTO partnerships that have increased the value of health-related inventions as measured by follow-on funding and industry involvement; either as a consulting partner or licensee.
Phagocytic leukocytes, predominantly macrophages, not only ingest and destroy invading pathogens, but are charged with clearing dead and dying host cells. The process of engulfing apoptotic cells is called efferocytosis and has long been appreciated for its role in the resolution of inflammation. New evidence is emerging that efferocytosis represents a double-edged sword in microbial immunity. Although efferocytosis of influenza and Mycobacterium tuberculosis-infected cells results in pathogen destruction, efferocytosis of Leishmania-infected neutrophils may promote infection. Understanding how macrophages, dendritic cells (DC) and neutrophils process pathogens encased within a dying cell could lead to the development of novel therapeutics that simultaneously suppress inflammation and promote pathogen clearance.
Clinical trials of vaccines against Mycobacterium tuberculosis are well under way and results are starting to come in. Some of these results are not so encouraging, as exemplified by the latest Aeras-422 and MVA85A trials. Other than empirically determining whether a vaccine reduces the number of cases of active tuberculosis, which is a daunting prospect given the chronic nature of the disease, we have no way of assessing vaccine efficacy. Therefore, investigators seek to identify biomarkers that predict vaccine efficacy. Historically, focus has been on the production of interferon-gamma by CD4(+) T cells, but this has not been a useful correlate of vaccine-induced protection. In this Opinion article, we discuss recent advances in our understanding of the immune control of M. tuberculosis and how this knowledge could be used for vaccine design and evaluation.