1
|
Nassiri M, Ghovvati S, Gharouni M, Tahmoorespur M, Bahrami AR, Dehghani H. Engineering Human Pancreatic RNase 1 as an Immunotherapeutic Agent for Cancer Therapy Through Computational and Experimental Studies. Protein J 2024; 43:316-332. [PMID: 38145445 DOI: 10.1007/s10930-023-10171-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 11/20/2023] [Indexed: 12/26/2023]
Abstract
Most plant and bacterial toxins are highly immunogenic with non-specific toxic effects. Human ribonucleases are thought to provide a promising basis for reducing the toxic agent's immunogenic properties, which are candidates for cancer therapy. In the cell, the ribonuclease inhibitor (RI) protein binds to the ribonuclease enzyme and forms a tight complex. This study aimed to engineer and provide a gene construct encoding an improved version of Human Pancreatic RNase 1 (HP-RNase 1) to reduce connection to RI and modulate the immunogenic effects of immunotoxins. To further characterize the interaction complex of HP-RNase 1 and RI, we established various in silico and in vitro approaches. These methods allowed us to specifically monitor interactions within native and engineered HP-RNase 1/RI complexes. In silico research involved molecular dynamics (MD) simulations of native and mutant HP-RNase 1 in their free form and when bound to RI. For HP-RNase 1 engineering, we designed five mutations (K8A/N72A/N89A/R92D/E112/A) based on literature studies, as this combination proved effective for the intended investigation. Then, the cDNA encoding HP-RNase 1 was generated by RT-PCR from blood and cloned into the pSYN2 expression vector. Consequently, wild-type and the engineered HP-RNase 1 were over-expressed in E. coli TG1 and purified using an IMAC column directed against a poly-his tag. The protein products were detected by SDS-PAGE and Western blot analysis. HP-RNase 1 catalytic activity, in the presence of various concentrations of RI, demonstrated that the mutated version of the protein is able to escape the ribonuclease inhibitor and target the RNA substrate 2.5 folds more than that of the wild type. From these data, we tend to suggest the engineered recombinant HP-RNase 1 potentially as a new immunotherapeutic agent for application in human cancer therapy.
Collapse
Affiliation(s)
- Mohammadreza Nassiri
- Department of Animal Science, College of Agriculture, Ferdowsi University of Mashhad, Mashhad, Iran
- Institute of Biotechnology, Ferdowsi University of Mashhad, Mashhad, Iran
| | - Shahrokh Ghovvati
- Department of Animal Sciences, Faculty of Agriculture, University of Guilan, 41635-1314, Rasht, Guilan, Iran.
| | - Marzieh Gharouni
- Department of Biochemistry, Ferdowsi University of Mashhad, Mashhad, Iran.
| | - Mojtaba Tahmoorespur
- Department of Animal Science, College of Agriculture, Ferdowsi University of Mashhad, Mashhad, Iran
- Institute of Biotechnology, Ferdowsi University of Mashhad, Mashhad, Iran
| | - Ahmad Reza Bahrami
- Institute of Biotechnology, Ferdowsi University of Mashhad, Mashhad, Iran
- Department of Molecular Cell Biology, College of Applied Science, Ferdowsi University of Mashhad, Mashhad, Iran
| | - Hesam Dehghani
- Institute of Biotechnology, Ferdowsi University of Mashhad, Mashhad, Iran
- Department of Physiology, School of Veterinary Medicine, Ferdowsi University of Mashhad, Mashhad, Iran
| |
Collapse
|
2
|
Role of the Ribonuclease ONCONASE in miRNA Biogenesis and tRNA Processing: Focus on Cancer and Viral Infections. Int J Mol Sci 2022; 23:ijms23126556. [PMID: 35742999 PMCID: PMC9223570 DOI: 10.3390/ijms23126556] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2022] [Revised: 05/25/2022] [Accepted: 06/09/2022] [Indexed: 12/23/2022] Open
Abstract
The majority of transcribed RNAs do not codify for proteins, nevertheless they display crucial regulatory functions by affecting the cellular protein expression profile. MicroRNAs (miRNAs) and transfer RNA-derived small RNAs (tsRNAs) are effectors of interfering mechanisms, so that their biogenesis is a tightly regulated process. Onconase (ONC) is an amphibian ribonuclease known for cytotoxicity against tumors and antiviral activity. Additionally, ONC administration in patients resulted in clinical effectiveness and in a well-tolerated feature, at least for lung carcinoma and malignant mesothelioma. Moreover, the ONC therapeutic effects are actually potentiated by cotreatment with many conventional antitumor drugs. This review not only aims to describe the ONC activity occurring either in different tumors or in viral infections but also to analyze the molecular mechanisms underlying ONC pleiotropic and cellular-specific effects. In cancer, data suggest that ONC affects malignant phenotypes by generating tRNA fragments and miRNAs able to downregulate oncogenes expression and upregulate tumor-suppressor proteins. In cells infected by viruses, ONC hampers viral spread by digesting the primer tRNAs necessary for viral DNA replication. In this scenario, new therapeutic tools might be developed by exploiting the action of ONC-elicited RNA derivatives.
Collapse
|
3
|
Gotte G, Menegazzi M. Biological Activities of Secretory RNases: Focus on Their Oligomerization to Design Antitumor Drugs. Front Immunol 2019; 10:2626. [PMID: 31849926 PMCID: PMC6901985 DOI: 10.3389/fimmu.2019.02626] [Citation(s) in RCA: 27] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2019] [Accepted: 10/22/2019] [Indexed: 12/11/2022] Open
Abstract
Ribonucleases (RNases) are a large number of enzymes gathered into different bacterial or eukaryotic superfamilies. Bovine pancreatic RNase A, bovine seminal BS-RNase, human pancreatic RNase 1, angiogenin (RNase 5), and amphibian onconase belong to the pancreatic type superfamily, while binase and barnase are in the bacterial RNase N1/T1 family. In physiological conditions, most RNases secreted in the extracellular space counteract the undesired effects of extracellular RNAs and become protective against infections. Instead, if they enter the cell, RNases can digest intracellular RNAs, becoming cytotoxic and having advantageous effects against malignant cells. Their biological activities have been investigated either in vitro, toward a number of different cancer cell lines, or in some cases in vivo to test their potential therapeutic use. However, immunogenicity or other undesired effects have sometimes been associated with their action. Nevertheless, the use of RNases in therapy remains an appealing strategy against some still incurable tumors, such as mesothelioma, melanoma, or pancreatic cancer. The RNase inhibitor (RI) present inside almost all cells is the most efficacious sentry to counteract the ribonucleolytic action against intracellular RNAs because it forms a tight, irreversible and enzymatically inactive complex with many monomeric RNases. Therefore, dimerization or multimerization could represent a useful strategy for RNases to exert a remarkable cytotoxic activity by evading the interaction with RI by steric hindrance. Indeed, the majority of the mentioned RNases can hetero-dimerize with antibody derivatives, or even homo-dimerize or multimerize, spontaneously or artificially. This can occur through weak interactions or upon introducing covalent bonds. Immuno-RNases, in particular, are fusion proteins representing promising drugs by combining high target specificity with easy delivery in tumors. The results concerning the biological features of many RNases reported in the literature are described and discussed in this review. Furthermore, the activities displayed by some RNases forming oligomeric complexes, the mechanisms driving toward these supramolecular structures, and the biological rebounds connected are analyzed. These aspects are offered with the perspective to suggest possible efficacious therapeutic applications for RNases oligomeric derivatives that could contemporarily lack, or strongly reduce, immunogenicity and other undesired side-effects.
Collapse
Affiliation(s)
- Giovanni Gotte
- Biological Chemistry Section, Department of Neuroscience, Biomedicine and Movement Sciences, University of Verona, Verona, Italy
| | - Marta Menegazzi
- Biological Chemistry Section, Department of Neuroscience, Biomedicine and Movement Sciences, University of Verona, Verona, Italy
| |
Collapse
|
4
|
Lim WQ, Phua SZF, Zhao Y. Redox-Responsive Polymeric Nanocomplex for Delivery of Cytotoxic Protein and Chemotherapeutics. ACS APPLIED MATERIALS & INTERFACES 2019; 11:31638-31648. [PMID: 31389684 DOI: 10.1021/acsami.9b09605] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/04/2023]
Abstract
Responsive delivery of anticancer proteins into cells is an emerging field in biological therapeutics. Currently, the delivery of proteins is highly compromised by multiple successive physiological barriers that reduce the therapeutic efficacy. Hence, there is a need to design a robust and sustainable nanocarrier to provide suitable protection of proteins and overcome the physiological barriers for better cellular accumulation. In this work, polyethylenimine (PEI) cross-linked by oxaliplatin(IV) prodrug (oxliPt(IV)) was used to fabricate a redox-responsive nanocomplex (PEI-oxliPt(IV)@RNBC/GOD) for the delivery of a reactive oxygen species-cleavable, reversibly caged RNase A protein (i.e., RNase A nitrophenylboronic conjugate, RNBC) and glucose oxidase (GOD) in order to realize efficient cancer treatment. The generation of hydrogen peroxide by GOD can uncage and restore the enzymatic activity of RNBC. On account of the responsiveness of the nanocomplex to highly reducing cellular environment, it would dissociate and release the protein and active oxaliplatin drug, causing cell death by both catalyzing RNA degradation and inhibiting DNA synthesis. As assessed by the RNA degradation assay, the activity of the encapsulated RNBC was recovered by the catalytic production of hydrogen peroxide from GOD and glucose substrate overexpressed in cancer cells. Monitoring of the changes in nanoparticle size confirmed that the nanocomplex could dissociate in the reducing environment, with the release of active oxaliplatin drug and protein. Confocal laser scanning microscopy (CLSM) and flow cytometry analysis revealed highly efficient accumulation of the nanocomplex as compared to free native proteins. In vitro cytotoxicity experiments using 4T1 cancer cells showed ∼80% cell killing efficacy, with highly efficient apoptosis induction. Assisted by the cationic polymeric carrier, it was evident from CLSM images that intracellular delivery of the therapeutic protein significantly depleted the RNA level. Thus, this work provides a promising platform for the delivery of therapeutic proteins and chemotherapeutic drugs for efficient cancer treatment.
Collapse
Affiliation(s)
- Wei Qi Lim
- NTU-Northwestern Institute for Nanomedicine, Interdisciplinary Graduate School , Nanyang Technological University , 50 Nanyang Drive , 637553 , Singapore
- Division of Chemistry and Biological Chemistry, School of Physical and Mathematical Sciences , Nanyang Technological University , 21 Nanyang Link , 637371 , Singapore
| | - Soo Zeng Fiona Phua
- Division of Chemistry and Biological Chemistry, School of Physical and Mathematical Sciences , Nanyang Technological University , 21 Nanyang Link , 637371 , Singapore
| | - Yanli Zhao
- NTU-Northwestern Institute for Nanomedicine, Interdisciplinary Graduate School , Nanyang Technological University , 50 Nanyang Drive , 637553 , Singapore
- Division of Chemistry and Biological Chemistry, School of Physical and Mathematical Sciences , Nanyang Technological University , 21 Nanyang Link , 637371 , Singapore
| |
Collapse
|
5
|
Optimization of Human Serum Albumin Periplasmic Localization in Escherichia coli Using In Silico Evaluation of Different Signal Peptides. Int J Pept Res Ther 2018. [DOI: 10.1007/s10989-018-9709-6] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
|
6
|
Groppelli E, Levy HC, Sun E, Strauss M, Nicol C, Gold S, Zhuang X, Tuthill TJ, Hogle JM, Rowlands DJ. Picornavirus RNA is protected from cleavage by ribonuclease during virion uncoating and transfer across cellular and model membranes. PLoS Pathog 2017; 13:e1006197. [PMID: 28166307 PMCID: PMC5325612 DOI: 10.1371/journal.ppat.1006197] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2016] [Revised: 02/24/2017] [Accepted: 01/22/2017] [Indexed: 12/04/2022] Open
Abstract
Picornaviruses are non-enveloped RNA viruses that enter cells via receptor-mediated endocytosis. Because they lack an envelope, picornaviruses face the challenge of delivering their RNA genomes across the membrane of the endocytic vesicle into the cytoplasm to initiate infection. Currently, the mechanism of genome release and translocation across membranes remains poorly understood. Within the enterovirus genus, poliovirus, rhinovirus 2, and rhinovirus 16 have been proposed to release their genomes across intact endosomal membranes through virally induced pores, whereas one study has proposed that rhinovirus 14 releases its RNA following disruption of endosomal membranes. For the more distantly related aphthovirus genus (e.g. foot-and-mouth disease viruses and equine rhinitis A virus) acidification of endosomes results in the disassembly of the virion into pentamers and in the release of the viral RNA into the lumen of the endosome, but no details have been elucidated as how the RNA crosses the vesicle membrane. However, more recent studies suggest aphthovirus RNA is released from intact particles and the dissociation to pentamers may be a late event. In this study we have investigated the RNase A sensitivity of genome translocation of poliovirus using a receptor-decorated-liposome model and the sensitivity of infection of poliovirus and equine-rhinitis A virus to co-internalized RNase A. We show that poliovirus genome translocation is insensitive to RNase A and results in little or no release into the medium in the liposome model. We also show that infectivity is not reduced by co-internalized RNase A for poliovirus and equine rhinitis A virus. Additionally, we show that all poliovirus genomes that are internalized into cells, not just those resulting in infection, are protected from RNase A. These results support a finely coordinated, directional model of viral RNA delivery that involves viral proteins and cellular membranes. Picornaviruses are a large family of important human and animal pathogens that include poliovirus, human rhinovirus and foot-and-mouth disease virus. Picornaviruses enter the host cell by hijacking one of the vesicle-mediated cellular entry routes. However, once the virus is internalized, the mechanism used to deliver the viral genome across the vesicle membrane and into the cytoplasm remains unclear and even controversial. Here we show that for poliovirus (a member of the enterovirus genus), viral RNA is translocated directly from the particle, across the vesicle membrane into the lumen of liposomes in a receptor-decorated liposome model, or cytoplasm during infection, without being exposed to external medium surrounding the liposomes or the lumen of the entry vesicle, respectively. Our results suggest that the interaction between the viral particle and the membrane results in a specific mechanism of viral genome delivery that not only directs but also protects the RNA so that it reaches the cytoplasm as an intact and functional molecule. Additionally, we show that this is also the case for equine rhinitis A virus, a member of the aphthovirus genus, whose genome delivery mechanism has previously been thought to differ significantly from the mechanism used by enteroviruses suggesting the possibility of a unified mechanism of RNA delivery for the entire picornavirus family.
Collapse
Affiliation(s)
- Elisabetta Groppelli
- School of Molecular and Cellular Biology & Astbury Centre for Structural Molecular Biology, Faculty of Biological Sciences, University of Leeds, Leeds, West Yorkshire, United Kingdom
| | - Hazel C. Levy
- Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, Massachusetts, United States of America
| | - Eileen Sun
- Program in Virology and Department of Chemistry and Chemical Biology, Harvard University, Cambridge, Massachusetts, United States of America
| | - Mike Strauss
- Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, Massachusetts, United States of America
| | - Clare Nicol
- School of Molecular and Cellular Biology & Astbury Centre for Structural Molecular Biology, Faculty of Biological Sciences, University of Leeds, Leeds, West Yorkshire, United Kingdom
| | - Sarah Gold
- The Pirbright Institute, Pirbright, Surrey, United Kingdom
| | - Xiaowei Zhuang
- Howard Hughes Institute and Department of Chemistry and Chemical Biology, Harvard University, Cambridge, Massachusetts, United States of America
| | | | - James M. Hogle
- Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, Massachusetts, United States of America
- * E-mail: (JMH); (DJR)
| | - David J. Rowlands
- School of Molecular and Cellular Biology & Astbury Centre for Structural Molecular Biology, Faculty of Biological Sciences, University of Leeds, Leeds, West Yorkshire, United Kingdom
- * E-mail: (JMH); (DJR)
| |
Collapse
|
7
|
VHL-dependent alterations in the secretome of renal cell carcinoma: Association with immune cell response? Oncotarget 2016; 6:43420-37. [PMID: 26486078 PMCID: PMC4791241 DOI: 10.18632/oncotarget.5560] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2015] [Accepted: 09/29/2015] [Indexed: 12/18/2022] Open
Abstract
Secreted proteins could modulate the interaction between tumor, stroma and immune cells within the tumor microenvironment thereby mounting an immunosuppressive tumor microenvironment. In order to determine the secretome-mediated, von Hippel Lindau (VHL)-regulated cross-talk between tumor cells and T lymphocytes peripheral blood mononuclear cells (PBMC) from healthy donors were either cultured in conditioned media obtained from normoxic and hypoxic human VHL-deficient renal cell carcinoma (RCC) cell line (786-0VHL−) and its wild type (wt) VHL-transfected counterpart (786-0VHL+) or directly co-cultured with both cell lines. An increased T cell proliferation was detected in the presence of 786-0VHL+-conditioned medium. By applying a quantitative proteomic-based approach using differential gel electrophoresis followed by mass spectrometry fourteen proteins were identified to be differentially expressed within the secretome of 786-0VHL− cells when compared to that of 786-0VHL+ cells. All proteins identified were involved in multiple tumor-associated biological functions including immune responses. Functional studies on manganese superoxide dismutase 2 (MnSOD2) demonstrated that it was a regulator of T cell activation-induced oxidative signaling and cell death. Direct effects of soluble MnSOD2 on the growth properties and interleukin 2 (IL-2) secretion of T cells could be demonstrated underlining the critical role of extracellular MnSOD2 levels for T cell proliferation and activation.
Collapse
|
8
|
Dubois JLN, Lavignac N. Cationic poly(amidoamine) promotes cytosolic delivery of bovine RNase A in melanoma cells, while maintaining its cellular toxicity. J Mater Chem B 2015; 3:6501-6508. [PMID: 32262558 DOI: 10.1039/c4tb02065k] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
Ribonucleases are known to cleave ribonucleic acids, inducing cell death. RNase A, a member of the ribonuclease family, generally displayed poor in vitro activity. This has been attributed to factors such as low intracellular delivery. Poly(amidoamine)s have been used to promote the translocation of non-permeant proteins to the cytosol. Our objective was to demonstrate that poly(amidoamine)s could potentially promote the delivery of RNase A to selected cell line. Interactions of three cationic poly(amidoamine)s (P1, P2 and ISA1) with wild-type bovine RNase A were investigated using gel retardation assays, DLS and microcalorimetry. Although the polymers and the protein are essentially cationic at physiological pH, complexation between the PAAs and RNase A was observed. The high sensitivity differential scanning calorimetry (HSDSC) thermograms demonstrated that the thermal stability of the protein was reduced when complexed with ISA1 (Tmax decreased by 6.5 °C) but was not affected by P1 and P2. All the polymers displayed low cytotoxicity towards non-cancerous cells (IC50 > 3.5 mg mL-1). While RNase A alone was not toxic to mouse melanoma cells (B16F1), P1 was able to promote cytosolic delivery of biologically active RNase A, increasing cell death (IC50 = 0.09 mg mL-1).
Collapse
Affiliation(s)
- Julie L N Dubois
- Medway School of Pharmacy, Universities of Kent and Greenwich at Medway, Central Avenue, Chatham ME4 4TB, UK.
| | | |
Collapse
|
9
|
Spadaccini R, Ercole C, Graziano G, Wechselberger R, Boelens R, Picone D. Mechanism of 3D domain swapping in bovine seminal ribonuclease. FEBS J 2014; 281:842-50. [PMID: 24616921 PMCID: PMC7164040 DOI: 10.1111/febs.12651] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/04/2022]
Abstract
3D domain swapping (3D‐DS) is a complex protein aggregation process for which no unique mechanism exists. We report an analysis of 3D‐DS in bovine seminal ribonuclease, a homodimeric protein whose subunits are linked by two disulfide bridges, based on NMR and biochemical studies. The presence of the covalent bonds between the subunits stabilizes the unswapped dimer, and allows distinct evaluation of the structural and dynamic effects of the swapping with respect to the dimerization process. In comparison with the monomeric subunit, which, in solution has a compact structure without any propensity for local unfolding, both swapped and unswapped dimers show increased flexibility. NMR analysis, together with urea denaturation and hydrogen–deuterium exchange data, indicates that the two dimers have increased conformational fluctuations. Furthermore, we found that the rate‐limiting step of both the swapping and unswapping pathways is the detachment of the N‐terminal helices from the monomers. These results suggest a new general mechanism in which a dimeric intermediate could facilitate 3D‐DS in globular proteins. Structured digital abstract http://www.uniprot.org/uniprot/P00669 and http://www.uniprot.org/uniprot/P00669 http://www.ebi.ac.uk/ontology-lookup/?termId=MI:0407 by http://www.ebi.ac.uk/ontology-lookup/?termId=MI:0077 (http://www.ebi.ac.uk/intact/interaction/EBI-8870415)
Collapse
|
10
|
Schirrmann T, Frenzel A, Linden L, Stelte-Ludwig B, Willuda J, Harrenga A, Dübel S, Müller-Tiemann B, Trautwein M. Evaluation of human pancreatic RNase as effector molecule in a therapeutic antibody platform. MAbs 2014; 6:367-80. [PMID: 24492302 DOI: 10.4161/mabs.27830] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
Human antibody-ribonuclease (RNase) fusion proteins, referred to as immunoRNases, have been proposed as an alternative to heterologous immunotoxins, without their immunogenicity and unspecific toxicity issues. In this study, we investigated if human pancreatic RNase will be suitable as effector component in a therapeutic antibody development platform. We generated several fusion proteins consisting of tumor-specific human immunoglobulins (IgGs) and human pancreatic RNase. Transient mammalian cell production was efficient and IgG-RNases were purified to homogeneity. Antigen binding was comparable to the parental antibodies and RNase catalytic activity was retained even in the presence of 50-fold molar excess of human cytosolic RNase inhibitor (RI). Serum stability, cell binding and internalization of IgG-RNases were comparable to the parental IgGs. Despite these promising properties, none of the IgG-RNases revealed significant inhibition of tumor cell growth in vitro even when targeting different antigens putatively employing different endocytotic pathways. The introduction of different linkers containing endosomal protease cleavage sites into the IgG-RNase did not enhance cytotoxicity. Similarly, RI evasive human pancreatic RNase variants mediated only small inhibiting effects on tumor cell growth at high concentrations, potentially reflecting inefficient cytosolic translocation. Taken together, human pancreatic RNase and variants did not prove to be generally suitable as effector component for a therapeutic antibody drug development platform.
Collapse
Affiliation(s)
- Thomas Schirrmann
- University of Braunschweig; Institute of Biochemistry, Biotechnology and Bioinformatics; Braunschweig, Germany
| | - André Frenzel
- University of Braunschweig; Institute of Biochemistry, Biotechnology and Bioinformatics; Braunschweig, Germany
| | - Lars Linden
- Bayer Healthcare AG; Global Biologics; Wuppertal, Germany
| | | | - Jörg Willuda
- Bayer HealthCare AG; Therapeutic Research Group Oncology & Gynecological Therapies; Berlin, Germany
| | - Axel Harrenga
- Bayer Healthcare AG; Global Biologics; Wuppertal, Germany
| | - Stefan Dübel
- University of Braunschweig; Institute of Biochemistry, Biotechnology and Bioinformatics; Braunschweig, Germany
| | | | - Mark Trautwein
- Bayer Healthcare AG; Global Biologics; Wuppertal, Germany
| |
Collapse
|
11
|
Sundlass NK, Eller CH, Cui Q, Raines RT. Contribution of electrostatics to the binding of pancreatic-type ribonucleases to membranes. Biochemistry 2013; 52:6304-12. [PMID: 23947917 DOI: 10.1021/bi400619m] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
Pancreatic-type ribonucleases show clinical promise as chemotherapeutic agents but are limited in efficacy by the inefficiency of their uptake by human cells. Cellular uptake can be increased by the addition of positive charges to the surface of ribonucleases, either by site-directed mutagenesis or by chemical modification. This observation has led to the hypothesis that ribonuclease uptake by cells depends on electrostatics. Here, we use a combination of experimental and computational methods to ascertain the contribution of electrostatics to the cellular uptake of ribonucleases. We focus on three homologous ribonucleases: Onconase (frog), ribonuclease A (cow), and ribonuclease 1 (human). Our results support the hypothesis that electrostatics are necessary for the cellular uptake of Onconase. In contrast, specific interactions with cell-surface components likely contribute more to the cellular uptake of ribonuclease A and ribonuclease 1 than do electrostatics. These findings provide insight for the design of new cytotoxic ribonucleases.
Collapse
Affiliation(s)
- Nadia K Sundlass
- Medical Scientist Training Program and Graduate Program in Biophysics, ‡Department of Biochemistry, and §Department of Chemistry, University of Wisconsin-Madison , Madison, Wisconsin 53706, United States
| | | | | | | |
Collapse
|
12
|
Stehle F, Schulz K, Fahldieck C, Kalich J, Lichtenfels R, Riemann D, Seliger B. Reduced immunosuppressive properties of axitinib in comparison with other tyrosine kinase inhibitors. J Biol Chem 2013; 288:16334-16347. [PMID: 23625925 DOI: 10.1074/jbc.m112.437962] [Citation(s) in RCA: 47] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
The multikinase inhibitors sunitinib, sorafenib, and axitinib have an impact not only on tumor growth and angiogenesis, but also on the activity and function of immune effector cells. In this study, a comparative analysis of the growth inhibitory properties and apoptosis induction potentials of tyrosine kinase inhibitors on T cells was performed. Tyrosine kinase inhibitor treatment resulted in a dramatic decrease in T cell proliferation along with distinct impacts on the cell cycle progression. This was at least partially associated with an enhanced induction of apoptosis although triggered by distinct apoptotic mechanisms. In contrast to sunitinib and sorafenib, axitinib did not affect the mitochondrial membrane potential (Δψm) but resulted in an induction or stabilization of the induced myeloid leukemia cell differentiation protein (Mcl-1), leading to an irreversible arrest in the G2/M cell cycle phase and delayed apoptosis. Furthermore, the sorafenib-mediated suppression of immune effector cells, in particular the reduction of the CD8(+) T cell subset along with the down-regulation of key immune cell markers such as chemokine CC motif receptor 7 (CCR7), CD26, CD69, CD25, and CXCR3, was not observed in axitinib-treated immune effector cells. Therefore, axitinib rather than sorafenib seems to be suitable for implementation in complex treatment regimens of cancer patients including immunotherapy.
Collapse
Affiliation(s)
- Franziska Stehle
- Institute of Medical Immunology, Martin Luther University Halle-Wittenberg, 06112 Halle (Saale), Germany
| | - Kristin Schulz
- Institute of Medical Immunology, Martin Luther University Halle-Wittenberg, 06112 Halle (Saale), Germany
| | - Corinna Fahldieck
- Institute of Medical Immunology, Martin Luther University Halle-Wittenberg, 06112 Halle (Saale), Germany
| | - Jana Kalich
- Institute of Medical Immunology, Martin Luther University Halle-Wittenberg, 06112 Halle (Saale), Germany
| | - Rudolf Lichtenfels
- Institute of Medical Immunology, Martin Luther University Halle-Wittenberg, 06112 Halle (Saale), Germany
| | - Dagmar Riemann
- Institute of Medical Immunology, Martin Luther University Halle-Wittenberg, 06112 Halle (Saale), Germany
| | - Barbara Seliger
- Institute of Medical Immunology, Martin Luther University Halle-Wittenberg, 06112 Halle (Saale), Germany.
| |
Collapse
|
13
|
Sun X, Wiedeman A, Agrawal N, Teal TH, Tanaka L, Hudkins KL, Alpers CE, Bolland S, Buechler MB, Hamerman JA, Ledbetter JA, Liggitt D, Elkon KB. Increased ribonuclease expression reduces inflammation and prolongs survival in TLR7 transgenic mice. THE JOURNAL OF IMMUNOLOGY 2013; 190:2536-43. [PMID: 23382559 DOI: 10.4049/jimmunol.1202689] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
TLR7 activation is implicated in the pathogenesis of systemic lupus erythematosus. Mice that overexpress TLR7 develop a lupus-like disease with autoantibodies and glomerulonephritis and early death. To determine whether degradation of the TLR7 ligand RNA would alter the course of disease, we created RNase A transgenic (Tg) mice. We then crossed the RNase Tg to TLR7 Tg mice to create TLR7 × RNase double Tg (DTg) mice. DTg mice had a significantly increased survival associated with reduced activation of T and B lymphocytes and reduced kidney deposition of IgG and C3. We observed massive hepatic inflammation and cell death in TLR7 Tg mice. In contrast, hepatic inflammation and necrosis were strikingly reduced in DTg mice. These findings indicate that high concentrations of serum RNase protect against immune activation and inflammation associated with TLR7 stimulation and that RNase may be a useful therapeutic strategy in the prevention or treatment of inflammation in systemic lupus erythematosus and, possibly, liver diseases.
Collapse
Affiliation(s)
- Xizhang Sun
- Department of Medicine, University of Washington, Seattle, WA 98195, USA
| | | | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
14
|
Han GJ, Dong XY, Zhang L, Fu LT, Wang GZ, Sun Y. Facilitated oxidative refolding of ribonuclease A from inclusion bodies with a new redox system. Biochem Eng J 2012. [DOI: 10.1016/j.bej.2012.09.001] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
|
15
|
Lillich M, Chen X, Weil T, Barth H, Fahrer J. Streptavidin-conjugated C3 protein mediates the delivery of mono-biotinylated RNAse A into macrophages. Bioconjug Chem 2012; 23:1426-36. [PMID: 22681511 DOI: 10.1021/bc300041z] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The C3 toxin produced by Clostridium botulinum (C3bot) catalyzes the mono-ADP-ribosylation of the small GTPases Rho A, B and C, resulting in their inactivation. Recently, a specific endocytotic uptake mechanism of C3bot was identified in macrophages and myeloid leukemia cells. Here, we present a novel delivery system based upon a mutant C3bot devoid of ADP-ribosylation activity (C3Mut) and wild-type streptavidin (Stv). The C3Mut moiety mediates endocytosis into macrophages, whereas Stv functions as an adaptor protein for attaching biotinylated molecules to facilitate their subsequent internalization. First, a bioconjugate consisting of recombinant C3Mut and Stv was generated via a thioether linkage that tightly interacted with biotinylated bovine serum albumin as demonstrated by dot blot analysis. We then showed the internalization of C3Mut-Stv into J774A.1 macrophages by confocal microscopy and observed translocation into the cytosol using cell fractionation. The C3Mut-Stv bioconjugate did not affect cell viability. Next, we prepared mono-biotinylated RNase A, which was attached to the C3Mut-Stv transporter, and demonstrated its C3Mut-Stv-mediated delivery into the cytosol of J774A.1 cells. Finally, C3Mut-Stv also promoted the efficient uptake of mono-biotinylated lysozyme into J774A.1 cells, highlighting its versatility. This study intriguingly demonstrates the use of the novel C3Mut-Stv delivery system for protein transduction and may provide a basis for future applications, in particular, of cytotoxic RNase A mutants.
Collapse
Affiliation(s)
- Maren Lillich
- Institute of Pharmacology and Toxicology, University of Ulm Medical Center, Albert-Einstein-Allee 11, D-89081 Ulm, Germany
| | | | | | | | | |
Collapse
|
16
|
Abstract
Mammalian pancreatic-type ribonucleases (ptRNases) comprise an enzyme family that is remarkably well suited for therapeutic exploitation. ptRNases are robust and prodigious catalysts of RNA cleavage that can naturally access the cytosol. Instilling cytotoxic activity requires endowing them with the ability to evade a cytosolic inhibitor protein while retaining other key attributes. These efforts have informed our understanding of ptRNase-based cytotoxins, as well as the action of protein-based drugs with cytosolic targets. Here, we address the most pressing problems encountered in the design of cytotoxic ptRNases, along with potential solutions. In addition, we describe assays that can be used to evaluate a successful design in vitro, in cellulo, and in vivo. The emerging information validates the continuing development of ptRNases as chemotherapeutic agents.
Collapse
Affiliation(s)
- Jo E Lomax
- Graduate Program in Cellular & Molecular Biology, University of Wisconsin-Madison, Madison, Wisconsin, USA
| | | | | |
Collapse
|
17
|
D'Errico G, Ercole C, Lista M, Pizzo E, Falanga A, Galdiero S, Spadaccini R, Picone D. Enforcing the positive charge of N-termini enhances membrane interaction and antitumor activity of bovine seminal ribonuclease. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2011; 1808:3007-15. [DOI: 10.1016/j.bbamem.2011.08.009] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/20/2011] [Revised: 07/29/2011] [Accepted: 08/04/2011] [Indexed: 11/29/2022]
|
18
|
Sundlass NK, Raines RT. Arginine residues are more effective than lysine residues in eliciting the cellular uptake of onconase. Biochemistry 2011; 50:10293-9. [PMID: 21980976 DOI: 10.1021/bi200979k] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023]
Abstract
Onconase is an amphibian member of the pancreatic ribonuclease family of enzymes that is in clinical trials for the treatment of cancer. Onconase, which has an abundance of lysine residues, is internalized by cancer cells through endocytosis in a mechanism similar to that of cell-penetrating peptides. Here, we compare the effect of lysine versus arginine residues on the biochemical attributes necessary for Onconase to elicit its cytotoxic activity. In the variant R-Onconase, 10 of the 12 lysine residues in Onconase are replaced with arginine, leaving only the two active-site lysines intact. Cytometric assays quantifying internalization showed a 3-fold increase in the internalization of R-Onconase compared with Onconase. R-Onconase also showed greater affinity for heparin and a 2-fold increase in ribonucleolytic activity. Nonetheless, arginine substitution endowed only a slight increase in toxicity toward human cancer cells. Analysis of denaturation induced with guanidine-HCl showed that R-Onconase has less conformational stability than does the wild-type enzyme; moreover, R-Onconase is more susceptible to proteolytic degradation. These data indicate that arginine residues are more effective than lysine in eliciting cellular internalization but can compromise other aspects of protein structure and function.
Collapse
Affiliation(s)
- Nadia K Sundlass
- Medical Scientist Training Program and Biophysics Graduate Program, University of Wisconsin-Madison, Madison, Wisconsin 53706, United States
| | | |
Collapse
|
19
|
Chao TY, Raines RT. Mechanism of ribonuclease A endocytosis: analogies to cell-penetrating peptides. Biochemistry 2011; 50:8374-82. [PMID: 21827164 PMCID: PMC3242730 DOI: 10.1021/bi2009079] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
Pancreatic-type ribonucleases can exert toxic activity by catalyzing the degradation of cellular RNA. Their ability to enter cells is essential for their cytotoxicity. Here, we determine the mechanism by which bovine pancreatic ribonuclease (RNase A) enters human cells. Inhibiting clathrin-dependent endocytosis with dynasore or chlorpromazine decreases RNase A-uptake by ~70%. Limited colocalization between RNase A and transferrin indicates that RNase A is not routed through recycling endosomes. Instead, vesicular staining of RNase A overlaps substantially with that of nona-arginine and the cationic peptide corresponding to residues 47-57 of the HIV-1 TAT protein. At low concentrations (<5 μM), internalization of RNase A and these cell-penetrating peptides (CPPs) is inhibited by chlorpromazine as well as the macropinocytosis inhibitors cytochalasin D and 5-(N-ethyl-N-isopropyl)amiloride to a similar extent, indicative of common endocytic mechanism. At high concentrations, CPPs adopt a nonendocytic mechanism of cellular entry that is not shared by RNase A. Collectively, these data suggest that RNase A is internalized via a multipathway mechanism that involves both clathrin-coated vesicles and macropinosomes. The parallel between the uptake of RNase A and CPPs validates reference to RNase A as a "cell-penetrating protein".
Collapse
Affiliation(s)
- Tzu-Yuan Chao
- Department of Biochemistry, University of Wisconsin–Madison, Madison, Wisconsin 53706, United States
| | - Ronald T. Raines
- Department of Biochemistry, University of Wisconsin–Madison, Madison, Wisconsin 53706, United States
- Department of Chemistry, University of Wisconsin–Madison, Madison, Wisconsin 53706, United States
| |
Collapse
|
20
|
|
21
|
Andrady C, Sharma SK, Chester KA. Antibody-enzyme fusion proteins for cancer therapy. Immunotherapy 2011; 3:193-211. [PMID: 21322759 DOI: 10.2217/imt.10.90] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023] Open
Abstract
Advances in biomolecular technology have allowed the development of genetically fused antibody-enzymes. Antibody-enzyme fusion proteins have been used to target tumors for cancer therapy in two ways. In one system, an antibody-enzyme is pretargeted to the tumor followed by administration of an inactive prodrug that is converted to its active form by the pretargeted enzyme. This system has been described as antibody-directed enzyme prodrug therapy. The other system uses antibody-enzyme fusion proteins as direct therapeutics, where the enzyme is toxic in its own right. The key feature in this approach is that the antibody is used to internalize the toxic enzyme into the tumor cell, which activates cell-death processes. This antibody-enzyme system has been largely applied to deliver ribonucleases. This article addresses these two antibody-enzyme targeting strategies for cancer therapy from concept to (pre)clinical trials.
Collapse
Affiliation(s)
- Carima Andrady
- Cancer Research UK Targeting & Imaging Group, Department of Oncology, UCL Cancer Institute, Paul O'Gorman Building, University College London, 72 Huntley Street, London WC1E6BT, UK.
| | | | | |
Collapse
|
22
|
Arnold U, Leich F, Neumann P, Lilie H, Ulbrich-Hofmann R. Crystal structure of RNase A tandem enzymes and their interaction with the cytosolic ribonuclease inhibitor. FEBS J 2010; 278:331-40. [PMID: 21134128 DOI: 10.1111/j.1742-4658.2010.07957.x] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Because of their ability to degrade RNA, RNases are potent cytotoxins. The cytotoxic activity of most members of the RNase A superfamily, however, is abolished by the cytosolic ribonuclease inhibitor (RI). RNase A tandem enzymes, in which two RNase A molecules are artificially connected by a peptide linker, and thus have a pseudodimeric structure, exhibit remarkable cytotoxic activity. In vitro, however, these enzymes are still inhibited by RI. Here, we present the crystal structures of three tandem enzymes with the linker sequences GPPG, SGSGSG, and SGRSGRSG, which allowed us to analyze the mode of binding of RI to the RNase A tandem enzymes. Modeling studies with the crystal structures of the RI-RNase A complex and the SGRSGRSG-RNase A tandem enzyme as templates suggested a 1 : 1 binding stoichiometry for the RI-RNase A tandem enzyme complex, with binding of the RI molecule to the N-terminal RNase A entity. These results were experimentally verified by analytical ultracentrifugation, quantitative electrophoresis, and proteolysis studies with trypsin. As other dimeric RNases, which are comparably cytotoxic, either evade RI binding or potentially even bind two RI molecules, inactivation by RI cannot be the crucial limitation to the cytotoxicity of dimeric RNases.
Collapse
Affiliation(s)
- Ulrich Arnold
- Department of Biochemistry and Biotechnology, Martin-Luther University Halle-Wittenberg, Halle, Germany.
| | | | | | | | | |
Collapse
|
23
|
Giancola C, Ercole C, Fotticchia I, Spadaccini R, Pizzo E, D’Alessio G, Picone D. Structure-cytotoxicity relationships in bovine seminal ribonuclease: new insights from heat and chemical denaturation studies on variants. FEBS J 2010; 278:111-22. [DOI: 10.1111/j.1742-4658.2010.07937.x] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
|
24
|
Chao TY, Lavis LD, Raines RT. Cellular uptake of ribonuclease A relies on anionic glycans. Biochemistry 2010; 49:10666-73. [PMID: 21062061 DOI: 10.1021/bi1013485] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Bovine pancreatic ribonuclease (RNase A) can enter human cells, even though it lacks a cognate cell-surface receptor protein. Here, we report on the biochemical basis for its cellular uptake. Analyses in vitro and in cellulo revealed that RNase A interacts tightly with abundant cell-surface proteoglycans containing glycosaminoglycans, such as heparan sulfate and chondroitin sulfate, as well as with sialic acid-containing glycoproteins. The uptake of RNase A correlates with cell anionicity, as quantified by measuring electrophoretic mobility. The cellular binding and uptake of RNase A contrast with those of Onconase, an amphibian homologue that does not interact tightly with anionic cell-surface glycans. As anionic glycans are especially abundant on human tumor cells, our data predicate utility for mammalian ribonucleases as cancer chemotherapeutic agents.
Collapse
Affiliation(s)
- Tzu-Yuan Chao
- Department of Biochemistry, University of Wisconsin—Madison, Madison, Wisconsin 53706, United States
| | | | | |
Collapse
|
25
|
Chang CH, Gupta P, Michel R, Loo M, Wang Y, Cardillo TM, Goldenberg DM. Ranpirnase (frog RNase) targeted with a humanized, internalizing, anti-Trop-2 antibody has potent cytotoxicity against diverse epithelial cancer cells. Mol Cancer Ther 2010; 9:2276-86. [PMID: 20663928 DOI: 10.1158/1535-7163.mct-10-0338] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Ranpirnase (Rap), an amphibian RNase, has been extensively studied both preclinically and clinically as an antitumor agent. Rap can be administered repeatedly to patients without any untoward immune response, with reversible renal toxicity reported to be dose limiting. To enhance its potency and targeted tumor therapy, we describe the generation of a novel IgG-based immunotoxin, designated 2L-Rap(Q)-hRS7, comprising Rap(Q), a mutant Rap with the putative N-glycosylation site removed, and hRS7, an internalizing, humanized antibody against Trop-2, a cell surface glycoprotein overexpressed in variety of epithelial cancers. The immunotoxin was generated recombinantly by fusing Rap(Q) to each of the two hRS7 light (L) chains at the NH(2) terminus, produced in stably transfected myeloma cells, purified by Protein A, and evaluated by a panel of in vitro studies. The results, including size-exclusion high-performance liquid chromatography, SDS-PAGE, flow cytometry, RNase activity, internalization, cell viability, and colony formation, showed its purity, molecular integrity, comparable affinity to hRS7 for binding to several Trop-2-expressing cell lines of different cancer types, and potency to inhibit growth of these cell lines at nanomolar concentrations. In addition, 2L-Rap(Q)-hRS7 suppressed tumor growth in a prophylactic model of nude mice bearing Calu-3 human non-small cell lung cancer xenografts, with an increase in the median survival time from 55 to 96 days (P < 0.01). These results warrant further development of 2L-Rap(Q)-hRS7 as a potential therapeutic for various Trop-2-expressing cancers, such as cervical, breast, colon, pancreatic, ovarian, and prostate cancers.
Collapse
|
26
|
Abstract
Onconase (ONC) is a member of the ribonuclease A superfamily that is toxic to cancer cells in vitro and in vivo. ONC is now in Phase IIIb clinical trials for the treatment of malignant mesothelioma. Internalization of ONC to the cytosol of cancer cells is essential for its cytotoxic activity, despite the apparent absence of a cell-surface receptor protein. Endocytosis and cytotoxicity do, however, appear to correlate with the net positive charge of ribonucleases. To dissect the contribution made by the endogenous arginine and lysine residues of ONC to its cytotoxicity, 22 variants were created in which cationic residues were replaced with alanine. Variants with the same net charge (+2 to +5) as well as equivalent catalytic activity and conformational stability were found to exhibit large (> 10-fold) differences in toxicity for the cells of a human leukemia line. In addition, a more cationic ONC variant could be either much more or much less cytotoxic than a less cationic variant, again depending on the distribution of its cationic residues. The endocytosis of variants with widely divergent cytotoxic activity was quantified by flow cytometry using a small-molecule fluorogenic label, and was found to vary by twofold or less. This small difference in endocytosis did not account for the large difference in cytotoxicity, implicating the distribution of cationic residues as being critical for lipid-bilayer translocation subsequent to endocytosis. This finding has fundamental implications for understanding the interaction of ribonucleases and other proteins with mammalian cells.
Collapse
Affiliation(s)
- Rebecca F Turcotte
- Medical Scientist Training Program and Biophysics Graduate Program, University of Wisconsin-Madison, WI, USA
| | | | | |
Collapse
|
27
|
Makarov AA, Kolchinsky A, Ilinskaya ON. Binase and other microbial RNases as potential anticancer agents. Bioessays 2008; 30:781-90. [DOI: 10.1002/bies.20789] [Citation(s) in RCA: 66] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
|
28
|
Singhal SS, Yadav S, Drake K, Singhal J, Awasthi S. Hsf-1 and POB1 induce drug sensitivity and apoptosis by inhibiting Ralbp1. J Biol Chem 2008; 283:19714-29. [PMID: 18474607 PMCID: PMC2443664 DOI: 10.1074/jbc.m708703200] [Citation(s) in RCA: 49] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2007] [Revised: 05/01/2008] [Indexed: 11/06/2022] Open
Abstract
Hsf-1 (heat shock factor-1) is a transcription factor that is known to regulate cellular heat shock response through its binding with the multispecific transporter protein, Ralbp1. Results of present studies demonstrate that Hsf-1 causes specific and saturable inhibition of the transport activity of Ralbp1 and that the combination of Hsf-1 and POB1 causes nearly complete inhibition through specific bindings with Ralbp1. Augmentation of cellular levels of Hsf-1 and POB1 caused dramatic apoptosis in non-small cell lung cancer cell line H358 through Ralbp1 inhibition. These findings indicate a novel model for mutual regulation of Hsf-1 and Ralbp1 through Ralbp1-mediated sequestration of Hsf-1 in the cellular cytoskeleton and Hsf-1-mediated inhibition of the transport activity of membrane-bound Ralbp1.
Collapse
Affiliation(s)
- Sharad S Singhal
- Department of Molecular Biology and Immunology, University of North Texas Health Science Center, Fort Worth, Texas 76107-2699, USA
| | | | | | | | | |
Collapse
|