The online version of this article (doi:10.1186/1476-4598-11-65) contains supplementary material, which is available to authorized users.
Aneta Kwiatkowska, Sebastien Didier contributed equally to this work.
The authors declare that they have no competing interests.
AK performed the cell proliferation, in vitro invasion and lamellipodia formation studies and participated in the Rac activation assays. SD performed the RhoG and Rac activation studies and part of the colony formation assays. SF performed the brain slice invasion assay. YC performed the invadopodia formation assay. TW performed part of the colony formation assays. MEB provided the TMA slides and ER and JE interpreted and scored the TMA assays. NT supervised and coordinated performance of the brain slice assay and IHC staining. AC participated in the design of the study, implemented the RhoG activation assay and produced preliminary data for most of the functional assays. MS designed and coordinated the overall study and drafted the manuscript. All authors read and approved the final manuscript.
The invasion of glioblastoma cells into regions of the normal brain is a critical factor that limits current therapies for malignant astrocytomas. Previous work has identified roles for the Rho family guanine nucleotide exchange factors Trio and Vav3 in glioblastoma invasion. Both Trio and Vav3 act on the small GTPase RhoG. We therefore examined the role of RhoG in the invasive behavior of glioblastoma cells.
We found that siRNA-mediated depletion of RhoG strongly inhibits invasion of glioblastoma cells through brain slices ex vivo. In addition, depletion of RhoG has a marginal effect on glioblastoma cell proliferation, but significantly inhibits glioblastoma cell survival in colony formation assays. We also observed that RhoG is activated by both HGF and EGF, two factors that are thought to be clinically relevant drivers of glioblastoma invasive behavior, and that RhoG is overexpressed in human glioblastoma tumors versus non-neoplastic brain. In search of a mechanism for the contribution of RhoG to the malignant behavior of glioblastoma cells, we found that depletion of RhoG strongly inhibits activation of the Rac1 GTPase by both HGF and EGF. In line with this observation, we also show that RhoG contributes to the formation of lamellipodia and invadopodia, two functions that have been shown to be Rac1-dependent.
Our functional analysis of RhoG in the context of glioblastoma revealed a critical role for RhoG in tumor cell invasion and survival. These results suggest that targeting RhoG-mediated signaling presents a novel avenue for glioblastoma therapy.
Authors’ original file for figure 112943_2012_1073_MOESM1_ESM.pdf
Authors’ original file for figure 212943_2012_1073_MOESM2_ESM.pdf
Authors’ original file for figure 312943_2012_1073_MOESM3_ESM.pdf
Authors’ original file for figure 412943_2012_1073_MOESM4_ESM.pdf
Authors’ original file for figure 512943_2012_1073_MOESM5_ESM.pdf
Authors’ original file for figure 612943_2012_1073_MOESM6_ESM.pdf
Authors’ original file for figure 712943_2012_1073_MOESM7_ESM.pdf
Authors’ original file for figure 812943_2012_1073_MOESM8_ESM.pdf
Karlsson R, Pedersen ED, Wang Z, Brakebusch C: Rho GTPase function in tumorigenesis. Biochim Biophys Acta. 2009, 1796: 91-98. PubMed
Stupp R, Hegi ME, Mason WP, van den Bent MJ, Taphoorn MJ, Janzer RC: Effects of radiotherapy with concomitant and adjuvant temozolomide versus radiotherapy alone on survival in glioblastoma in a randomised phase III study: 5-year analysis of the EORTC-NCIC trial. Lancet Oncol. 2009, 10: 459-466. 10.1016/S1470-2045(09)70025-7 CrossRefPubMed
Blangy A, Vignal E, Schmidt S, Debant A, Gauthier-Rouviere C, Fort P: TrioGEF1 controls Rac- and Cdc42-dependent cell structures through the direct activation of rhoG. J Cell Sci. 2000, 113 (Pt 4): 729-739. PubMed
Koochekpour S, Jeffers M, Rulong S, Taylor G, Klineberg E, Hudson EA: Met and hepatocyte growth factor/scatter factor expression in human gliomas. Cancer Res. 1997, 57: 5391-5398. PubMed
de Bakker CD, Haney LB, Kinchen JM, Grimsley C, Lu M, Klingele D: Phagocytosis of apoptotic cells is regulated by a UNC-73/TRIO-MIG-2/RhoG signaling module and armadillo repeats of CED-12/ELMO. Curr Biol. 2004, 14: 2208-2216. 10.1016/j.cub.2004.12.029 CrossRef
Fritz G, Kaina B: Rho GTPases: promising cellular targets for novel anticancer drugs. Curr Cancer Drug Targets. 2006, 6: 1-14. PubMed
- The small GTPase RhoG mediates glioblastoma cell invasion
Michael E Berens
Nhan L Tran
- BioMed Central
Neu im Fachgebiet Onkologie
e.Med Kampagnen-Visual, Mail Icon II