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Ma Y, Gong Y, Cheng Z, Loganathan S, Kao C, Sarkaria JN, Abel TW, Wang J. Critical functions of RhoB in support of glioblastoma tumorigenesis. Neuro Oncol 2014; 17:516-25. [PMID: 25216671 DOI: 10.1093/neuonc/nou228] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023] Open
Abstract
BACKGROUND RhoB is a member of the Rho small GTPase family that regulates cytoskeletal dynamics and vesicle trafficking. The RhoB homologs, RhoA and RhoC, have been shown to promote cancer progression and metastasis. In contrast, the functions of RhoB in human cancers are context dependent. Although expression of RhoB inversely correlates with disease progression in several epithelial cancers, recent data suggest that RhoB may support malignant phenotypes in certain cancer types. METHODS We assessed RhoB protein levels in glioma surgical specimens and patient-derived xenografts. The roles of RhoB in glioblastoma were determined by loss-of-function and gain-of-function assays in vitro and in vivo. The impact on p53 and STAT3 signaling was investigated. RESULTS RhoB expression was similar in tumor specimens compared with normal neural tissues obtained from epilepsy surgery. RhoB was expressed in the vast majority of xenograft tumors and spheroid cultures. Knockdown of RhoB induced cell-cycle arrest and apoptosis and compromised in vivo tumorigenic potential. However, overexpression of wild-type RhoB or a constitutively active mutant (RhoB-V14) did not significantly affect cell growth, which suggests that RhoB is not a rate-limiting oncogenic factor and is consistent with the scarcity of RhoB mutations in human cancer. Knockdown of RhoB reduced basal STAT3 activity and impaired cytokine-induced STAT3 activation. In glioblastoma tumors retaining wild-type p53, depletion of RhoB also activated p53 and induced expression of p21(CIP1) (/WAF1). CONCLUSIONS Our data suggest that RhoB belongs to an emerging class of "nononcogene addiction" factors that are essential for maintenance of malignant phenotypes in human cancers.
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Affiliation(s)
- Yufang Ma
- Department of Neurological Surgery, Vanderbilt University Medical Center, Nashville, Tennessee (Y.M., Y.G., Z.C., C.K., J.W.); Department of Pathology, Microbiology and Immunology, Vanderbilt University Medical Center, Nashville, Tennessee (T.W.A.); Department of Cancer Biology, Vanderbilt University Medical Center, Nashville, Tennessee (J.W.); Department of Pain Management and Oncology, The Second Affiliated Hospital, Nanjing Medical University, Nanjing, China (Z.C.); Department of Neuroscience and Pharmacology, Meharry Medical College, Nashville, Tennessee (S.L.); Department of Radiation Oncology, Mayo Clinic, Rochester, Minnesota (J.N.S.)
| | - Yuanying Gong
- Department of Neurological Surgery, Vanderbilt University Medical Center, Nashville, Tennessee (Y.M., Y.G., Z.C., C.K., J.W.); Department of Pathology, Microbiology and Immunology, Vanderbilt University Medical Center, Nashville, Tennessee (T.W.A.); Department of Cancer Biology, Vanderbilt University Medical Center, Nashville, Tennessee (J.W.); Department of Pain Management and Oncology, The Second Affiliated Hospital, Nanjing Medical University, Nanjing, China (Z.C.); Department of Neuroscience and Pharmacology, Meharry Medical College, Nashville, Tennessee (S.L.); Department of Radiation Oncology, Mayo Clinic, Rochester, Minnesota (J.N.S.)
| | - Zhixiang Cheng
- Department of Neurological Surgery, Vanderbilt University Medical Center, Nashville, Tennessee (Y.M., Y.G., Z.C., C.K., J.W.); Department of Pathology, Microbiology and Immunology, Vanderbilt University Medical Center, Nashville, Tennessee (T.W.A.); Department of Cancer Biology, Vanderbilt University Medical Center, Nashville, Tennessee (J.W.); Department of Pain Management and Oncology, The Second Affiliated Hospital, Nanjing Medical University, Nanjing, China (Z.C.); Department of Neuroscience and Pharmacology, Meharry Medical College, Nashville, Tennessee (S.L.); Department of Radiation Oncology, Mayo Clinic, Rochester, Minnesota (J.N.S.)
| | - Sudan Loganathan
- Department of Neurological Surgery, Vanderbilt University Medical Center, Nashville, Tennessee (Y.M., Y.G., Z.C., C.K., J.W.); Department of Pathology, Microbiology and Immunology, Vanderbilt University Medical Center, Nashville, Tennessee (T.W.A.); Department of Cancer Biology, Vanderbilt University Medical Center, Nashville, Tennessee (J.W.); Department of Pain Management and Oncology, The Second Affiliated Hospital, Nanjing Medical University, Nanjing, China (Z.C.); Department of Neuroscience and Pharmacology, Meharry Medical College, Nashville, Tennessee (S.L.); Department of Radiation Oncology, Mayo Clinic, Rochester, Minnesota (J.N.S.)
| | - Crystal Kao
- Department of Neurological Surgery, Vanderbilt University Medical Center, Nashville, Tennessee (Y.M., Y.G., Z.C., C.K., J.W.); Department of Pathology, Microbiology and Immunology, Vanderbilt University Medical Center, Nashville, Tennessee (T.W.A.); Department of Cancer Biology, Vanderbilt University Medical Center, Nashville, Tennessee (J.W.); Department of Pain Management and Oncology, The Second Affiliated Hospital, Nanjing Medical University, Nanjing, China (Z.C.); Department of Neuroscience and Pharmacology, Meharry Medical College, Nashville, Tennessee (S.L.); Department of Radiation Oncology, Mayo Clinic, Rochester, Minnesota (J.N.S.)
| | - Jann N Sarkaria
- Department of Neurological Surgery, Vanderbilt University Medical Center, Nashville, Tennessee (Y.M., Y.G., Z.C., C.K., J.W.); Department of Pathology, Microbiology and Immunology, Vanderbilt University Medical Center, Nashville, Tennessee (T.W.A.); Department of Cancer Biology, Vanderbilt University Medical Center, Nashville, Tennessee (J.W.); Department of Pain Management and Oncology, The Second Affiliated Hospital, Nanjing Medical University, Nanjing, China (Z.C.); Department of Neuroscience and Pharmacology, Meharry Medical College, Nashville, Tennessee (S.L.); Department of Radiation Oncology, Mayo Clinic, Rochester, Minnesota (J.N.S.)
| | - Ty W Abel
- Department of Neurological Surgery, Vanderbilt University Medical Center, Nashville, Tennessee (Y.M., Y.G., Z.C., C.K., J.W.); Department of Pathology, Microbiology and Immunology, Vanderbilt University Medical Center, Nashville, Tennessee (T.W.A.); Department of Cancer Biology, Vanderbilt University Medical Center, Nashville, Tennessee (J.W.); Department of Pain Management and Oncology, The Second Affiliated Hospital, Nanjing Medical University, Nanjing, China (Z.C.); Department of Neuroscience and Pharmacology, Meharry Medical College, Nashville, Tennessee (S.L.); Department of Radiation Oncology, Mayo Clinic, Rochester, Minnesota (J.N.S.)
| | - Jialiang Wang
- Department of Neurological Surgery, Vanderbilt University Medical Center, Nashville, Tennessee (Y.M., Y.G., Z.C., C.K., J.W.); Department of Pathology, Microbiology and Immunology, Vanderbilt University Medical Center, Nashville, Tennessee (T.W.A.); Department of Cancer Biology, Vanderbilt University Medical Center, Nashville, Tennessee (J.W.); Department of Pain Management and Oncology, The Second Affiliated Hospital, Nanjing Medical University, Nanjing, China (Z.C.); Department of Neuroscience and Pharmacology, Meharry Medical College, Nashville, Tennessee (S.L.); Department of Radiation Oncology, Mayo Clinic, Rochester, Minnesota (J.N.S.)
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Genth H, Pauillac S, Schelle I, Bouvet P, Bouchier C, Varela-Chavez C, Just I, Popoff MR. Haemorrhagic toxin and lethal toxin from Clostridium sordellii strain vpi9048: molecular characterization and comparative analysis of substrate specificity of the large clostridial glucosylating toxins. Cell Microbiol 2014; 16:1706-21. [PMID: 24905543 DOI: 10.1111/cmi.12321] [Citation(s) in RCA: 40] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/02/2014] [Revised: 05/12/2014] [Accepted: 05/29/2014] [Indexed: 12/16/2022]
Abstract
Large clostridial glucosylating toxins (LCGTs) are produced by toxigenic strains of Clostridium difficile, Clostridium perfringens, Clostridium novyi and Clostridium sordellii. While most C. sordellii strains solely produce lethal toxin (TcsL), C. sordellii strain VPI9048 co-produces both hemorrhagic toxin (TcsH) and TcsL. Here, the sequences of TcsH-9048 and TcsL-9048 are provided, showing that both toxins retain conserved LCGT features and that TcsL and TcsH are highly related to Toxin A (TcdA) and Toxin B (TcdB) from C. difficile strain VPI10463. The substrate profile of the toxins was investigated with recombinant LCGT transferase domains (rN) and a wide panel of small GTPases. rN-TcsH-9048 and rN-TcdA-10463 glucosylated preferably Rho-GTPases but also Ras-GTPases to some extent. In this respect, rN-TcsH-9048 and rN-TcdA-10463 differ from the respective full-length TcsH-9048 and TcdA-10463, which exclusively glucosylate Rho-GTPases. rN-TcsL-9048 and full length TcsL-9048 glucosylate both Rho- and Ras-GTPases, whereas rN-TcdB-10463 and full length TcdB-10463 exclusively glucosylate Rho-GTPases. Vero cells treated with full length TcsH-9048 or TcdA-10463 also showed glucosylation of Ras, albeit to a lower extent than of Rho-GTPases. Thus, in vitro analysis of substrate spectra using recombinant transferase domains corresponding to the auto-proteolytically cleaved domains, predicts more precisely the in vivo substrates than the full length toxins. Except for TcdB-1470, all LCGTs evoked increased expression of the small GTPase RhoB, which exhibited cytoprotective activity in cells treated with TcsL isoforms, but pro-apoptotic activity in cells treated with TcdA, TcdB, and TcsH. All LCGTs induced a rapid dephosphorylation of pY118-paxillin and of pS144/141-PAK1/2 prior to actin filament depolymerization indicating that disassembly of focal adhesions is an early event leading to the disorganization of the actin cytoskeleton.
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Affiliation(s)
- Harald Genth
- Institute of Toxicology, Medical School Hannover, Hannover, Germany
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