Browsing by Subject "Tumor suppressor"

Now showing 1 - 8 of 8
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    Common ELF1 deletion in prostate cancer bolsters oncogenic ETS function, inhibits senescence and promotes docetaxel resistance
    (Impact Journals, 2018-05) Budka, Justin A.; Ferris, Mary W.; Capone, Matthew J.; Hollenhorst, Peter C.; Medical Sciences, IU School of Medicine
    ETS family transcription factors play major roles in prostate tumorigenesis with some acting as oncogenes and others as tumor suppressors. ETS factors can compete for binding at some cis-regulatory sequences, but display specific binding at others. Therefore, changes in expression of ETS family members during tumorigenesis can have complex, multimodal effects. Here we show that ELF1 was the most commonly down-regulated ETS factor in primary prostate tumors, and expression decreased further in metastatic disease. Genome-wide mapping in cell lines indicated that ELF1 has two distinct tumor suppressive roles mediated by distinct cis-regulatory sequences. First, ELF1 inhibited cell migration and epithelial-mesenchymal transition by interfering with oncogenic ETS functions at ETS/AP-1 cis-regulatory motifs. Second, ELF1 uniquely targeted and activated genes that promote senescence. Furthermore, knockdown of ELF1 increased docetaxel resistance, indicating that the genomic deletions found in metastatic prostate tumors may promote therapeutic resistance through loss of both RB1 and ELF1.
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    Correction: Identification of miPEP133 as a novel tumor-suppressor microprotein encoded by miR-34a pri-miRNA
    (Springer Nature, 2024-09-12) Kang, Min; Tang, Bo; Li, Jixi; Zhou, Ziyan; Liu, Kang; Wang, Rensheng; Jiang, Ziyan; Bi, Fangfang; Patrick, David; Kim, Dongin; Mitra, Anirban K.; Hartwich, Yang Yang; Medicine, School of Medicine
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    CTF Meeting 2012: Translation of the Basic Understanding of the Biology and Genetics of NF1, NF2, and Schwannomatosis Toward the Development of Effective Therapies
    (Wiley, 2014) Widemann, Brigitte C.; Acosta, Maria T.; Ammoun, Sylvia; Belzberg, Allan J.; Bernards, Andre; Blakeley, Jaishri; Bretscher, Antony; Cichowski, Karen; Clapp, D. Wade; Dombi, Eva; Evans, Gareth D.; Ferner, Rosalie; Fernandez-Valle, Cristina; Fisher, Michael J.; Giovannini, Marco; Gutmann, David H.; Hanemann, C. Oliver; Hennigan, Robert; Huson, Susan; Ingram, David; Kissil, Joe; Korf, Bruce R.; Legius, Eric; Packer, Roger J.; McClatchey, Andrea I.; McCormick, Frank; North, Kathryn; Pehrsson, Minja; Plotkin, Scott R.; Ramesh, Vijaya; Ratner, Nancy; Schirmer, Susann; Sherman, Larry; Schorry, Elizabeth; Stevenson, David; Stewart, Douglas R.; Ullrich, Nicole; Bakker, Annette C.; Morrison, Helen; Medicine, School of Medicine
    The neurofibromatoses (NF) are autosomal dominant genetic disorders that encompass the rare diseases NF1, NF2, and schwannomatosis. The NFs affect more people worldwide than Duchenne muscular dystrophy and Huntington's disease combined. NF1 and NF2 are caused by mutations of known tumor suppressor genes (NF1 and NF2, respectively). For schwannomatosis, although mutations in SMARCB1 were identified in a subpopulation of schwannomatosis patients, additional causative gene mutations are still to be discovered. Individuals with NF1 may demonstrate manifestations in multiple organ systems, including tumors of the nervous system, learning disabilities, and physical disfigurement. NF2 ultimately can cause deafness, cranial nerve deficits, and additional severe morbidities caused by tumors of the nervous system. Unmanageable pain is a key finding in patients with schwannomatosis. Although today there is no marketed treatment for NF-related tumors, a significant number of clinical trials have become available. In addition, significant preclinical efforts have led to a more rational selection of potential drug candidates for NF trials. An important element in fueling this progress is the sharing of knowledge. For over 20 years the Children's Tumor Foundation has convened an annual NF Conference, bringing together NF professionals to share novel findings, ideas, and build collaborations. The 2012 NF Conference held in New Orleans hosted over 350 NF researchers and clinicians. This article provides a synthesis of the highlights presented at the conference and as such, is a "state-of-the-field" for NF research in 2012.
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    Genetic disruption of the small GTPase RAC1 prevents plexiform neurofibroma formation in mice with neurofibromatosis type 1
    (Elsevier, 2020-07-17) Mund, Julie A.; Park, SuJung; Smith, Abbi E.; He, Yongzheng; Jiang, Li; Hawley, Eric; Roberson, Michelle J.; Mitchell, Dana K.; Abu-Sultanah, Mohannad; Yuan, Jin; Bessler, Waylan K.; Sandusky, George; Chen, Shi; Zhang, Chi; Rhodes, Steven D.; Clapp, D. Wade; Pediatrics, School of Medicine
    Neurofibromatosis type 1 (NF1) is a common cancer predisposition syndrome caused by mutations in the NF1 tumor suppressor gene. NF1 encodes neurofibromin, a GTPase-activating protein for RAS proto-oncogene GTPase (RAS). Plexiform neurofibromas are a hallmark of NF1 and result from loss of heterozygosity of NF1 in Schwann cells, leading to constitutively activated p21RAS. Given the inability to target p21RAS directly, here we performed an shRNA library screen of all human kinases and Rho-GTPases in a patient-derived NF1-/- Schwann cell line to identify novel therapeutic targets to disrupt PN formation and progression. Rho family members, including Rac family small GTPase 1 (RAC1), were identified as candidates. Corroborating these findings, we observed that shRNA-mediated knockdown of RAC1 reduces cell proliferation and phosphorylation of extracellular signal-regulated kinase (ERK) in NF1-/- Schwann cells. Genetically engineered Nf1flox/flox;PostnCre+ mice, which develop multiple PNs, also exhibited increased RAC1-GTP and phospho-ERK levels compared with Nf1flox/flox;PostnCre- littermates. Notably, mice in which both Nf1 and Rac1 loci were disrupted (Nf1flox/floxRac1flox/flox;PostnCre+) were completely free of tumors and had normal phospho-ERK activity compared with Nf1flox/flox ;PostnCre+ mice. We conclude that the RAC1-GTPase is a key downstream node of RAS and that genetic disruption of the Rac1 allele completely prevents PN tumor formation in vivo in mice.
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    Identification of miPEP133 as a novel tumor-suppressor microprotein encoded by miR-34a pri-miRNA
    (BMC, 2020-09-14) Kang, Min; Tang, Bo; Li, Jixi; Zhou, Ziyan; Liu, Kang; Wang, Rensheng; Jiang, Ziyan; Bi, Fangfang; Patrick, David; Kim, Dongin; Mitra, Anirban K.; Yang-Hartwich, Yang; Medical and Molecular Genetics, School of Medicine
    Background Very few proteins encoded by the presumed non-coding RNA transcripts have been identified. Their cellular functions remain largely unknown. This study identifies the tumor-suppressor function of a novel microprotein encoded by the precursor of miR-34a. It consists of 133 amino acid residues, thereby named as miPEP133 (pri-microRNA encoded peptide 133). Methods We overexpressed miPEP133 in nasopharyngeal carcinoma (NPC), ovarian cancer and cervical cancer cell lines to determine its effects on cell growth, apoptosis, migration, or invasion. Its impact on tumor growth was evaluated in a xenograft NPC model. Its prognostic value was analyzed using NPC clinical samples. We also conducted western blot, immunoprecipitation, mass spectrometry, confocal microscopy and flow cytometry to determine the underlying mechanisms of miPEP133 function and regulation. Results miPEP133 was expressed in normal human colon, stomach, ovary, uterus and pharynx. It was downregulated in cancer cell lines and tumors. miPEP133 overexpression induced apoptosis in cancer cells and inhibited their migration and invasion. miPEP133 inhibited tumor growth in vivo. Low miPEP133 expression was an unfavorable prognostic marker associated with advanced metastatic NPC. Wild-type p53 but not mutant p53 induced miPEP133 expression. miPEP133 enhanced p53 transcriptional activation and miR-34a expression. miPEP133 localized in the mitochondria to interact with mitochondrial heat shock protein 70kD (HSPA9) and prevent HSPA9 from interacting with its binding partners, leading to the decrease of mitochondrial membrane potential and mitochondrial mass. Conclusion miPEP133 is a tumor suppressor localized in the mitochondria. It is a potential prognostic marker and therapeutic target for multiple types of cancers.
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    Multiple Functional Motifs Are Required for the Tumor Suppressor Activity of a Constitutively-Active ErbB4 Mutant
    (JScholar, 2013) Gallo, Richard M.; Bryant, Ianthe N.; Mill, Christopher P.; Kaverman, Steven; Riese, David J., II; Microbiology and Immunology, School of Medicine
    ErbB4 (HER4) is a member of the ErbB family of receptor tyrosine kinases, which includes the Epidermal Growth Factor Receptor (EGFR/ErbB1), ErbB2 (HER2/Neu), and ErbB3 (HER3). Mounting evidence indicates that ErbB4, unlike EGFR or ErbB2, functions as a tumor suppressor in many human malignancies. Previous analyses of the constitutively-dimerized and -active ErbB4 Q646C mutant indicate that ErbB4 kinase activity and phosphorylation of ErbB4 Tyr1056 are both required for the tumor suppressor activity of this mutant in human breast, prostate, and pancreatic cancer cell lines. However, the cytoplasmic region of ErbB4 possesses additional putative functional motifs, and the contributions of these functional motifs to ErbB4 tumor suppressor activity have been largely underexplored. Here we demonstrate that ErbB4 BH3 and LXXLL motifs, which are thought to mediate interactions with Bcl family proteins and steroid hormone receptors, respectively, are required for the tumor suppressor activity of the ErbB4 Q646C mutant. Furthermore, abrogation of the site of ErbB4 cleavage by gamma-secretase also disrupts the tumor suppressor activity of the ErbB4 Q646C mutant. This last result suggests that ErbB4 cleavage and subcellular trafficking of the ErbB4 cytoplasmic domain may be required for the tumor suppressor activity of the ErbB4 Q646C mutant. Indeed, here we demonstrate that mutants that disrupt ErbB4 kinase activity, ErbB4 phosphorylation at Tyr1056, or ErbB4 cleavage by gamma-secretase also disrupt ErbB4 trafficking away from the plasma membrane and to the cytoplasm. This supports a model for ErbB4 function in which ErbB4 tumor suppressor activity is dependent on ErbB4 trafficking away from the plasma membrane and to the cytoplasm, mitochondria, and/or the nucleus.
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    Using VBIM Technique to Discover ARMC4/ODAD2 as a Novel Negative Regulator of NF-κB and a New Tumor Suppressor in Colorectal Cancer
    (MDPI, 2022-03-01) Martin, Matthew; Mundade, Rasika; Hartley, Antja-Voy; Jiang, Guanglong; Jin, Jiamin; Sun, Steven; Safa, Ahma; Sandusky, George; Liu, Yunlong; Lu, Tao; Pharmacology and Toxicology, School of Medicine
    Since nuclear factor (NF) κB plays pivotal roles in inflammation and cancer, understanding its regulation holds great promise for disease therapy. Using the powerful validation-based insertional mutagenesis (VBIM) technique established by us previously, we discovered armadillo repeat-containing protein 4 (ARMC4)/outer dynein arm docking complex subunit 2 (ODAD2), a rarely studied protein known to date, as a novel negative regulator of NF-κB in colorectal cancer (CRC). High expression of ARMC4 downregulated the expression of NF-κB-dependent genes, dramatically reduced NF-κB activity, cellular proliferation, anchorage-independent growth, and migratory ability in vitro, and significantly decreased xenograft tumor growth in vivo. Co-immunoprecipitation experiments demonstrated that ARMC4 forms a complex with NF-κB. Importantly, the lower ARMC4 expression in patient tumors than normal tissues indicates its potential tumor suppressor function in CRC. Collectively, we uncovered a completely new facet of ARMC4 function by identifying it as a novel NF-κB negative regulator, thus uncovering ARMC4 as a potential new therapeutic target in CRC.
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    ZNFX1 is a Novel Master Regulator in Epigenetically-induced Pathogen Mimicry and Inflammasome Signaling in Cancer
    (bioRxiv, 2024-10-21) Stojanovic, Lora; Abbotts, Rachel; Tripathi, Kaushlendra; Coon, Collin M.; Rajendran, Saranya; Farid, Elnaz Abbasi; Hostetter, Galen; Guarnieri, Joseph W.; Wallace, Douglas C.; Liu, Sheng; Wan, Jun; Calendo, Gennaro; Marker, Rebecca; Gohari, Zahra; Inayatullah, Mohammed M. A.; Tiwari, Vijay K.; Kader, Tanjina; Santagata, Sandro; Drapkin, Ronny; Kommoss, Stefan; Pfisterer, Jacobus; Konecny, Gottfried E.; Coopergard, Ryan; Issa, Jean-Pierre; Winterhoff, Boris J. N.; Topper, Michael J.; Sandusky, George E.; Miller, Kathy D.; Baylin, Stephen B.; Nephew, Kenneth P.; Rassool, Feyruz V.; Medical and Molecular Genetics, School of Medicine
    DNA methyltransferase and poly(ADP-ribose) polymerase inhibitors (DNMTis, PARPis) induce a stimulator of interferon (IFN) genes (STING)-dependent pathogen mimicry response (PMR) in ovarian (OC) and other cancers. We now show that combining DNMTis and PARPis upregulates expression of a little-studied nucleic-acid sensor, NFX1-type zinc finger-containing 1 protein (ZNFX1). We demonstrate that ZNFX1 is a novel master regulator for PMR induction in mitochondria, serving as a gateway for STING-dependent PMR. In patient OC databases, high ZNFX1 expression levels correlate with advanced stage disease. ZNFX1 expression alone significantly correlates with an increase in overall survival in a phase 3 trial for therapy-resistant OC patients receiving bevacizumab in combination with chemotherapy. In correlative RNA-seq data, inflammasome signaling through ZNFX1 correlates with abnormal vasculogenesis. ZNFX1 controls PMR signaling through the mitochondria and may serve as a biomarker to facilitate offering personalized therapy in OC patients, highlighting the strong translational significance of our findings.