Geranylgeranylated, but not farnesylated, RhoB suppresses Ras transformation of NIH-3T3 cells.
RhoB is a low molecular weight GTPase that is both farnesylated (RhoB-F) and geranylgeranylated (RhoB-GG) in cells. Based on data from rodent cell models, it has been suggested that RhoB displays differential effects on cell transformation, according to the nature of its prenylation. To test directly this hypothesis, we generated GTPase-deficient RhoB mutants that are exclusively either farnesylated or geranylgeranylated. We show that in Ras-transformed murine NIH-3T3 cells, RhoB-F enhances, whereas RhoB-GG and RhoB (F/GG) suppresses anchorage-dependent and -independent cell growth as well as tumor growth in nude mice. We then demonstrate that Ras constitutive activation of the tumor survival pathways Akt and NF-kappa B are blocked by RhoB-GG, but not by RhoB-F, providing further support for the opposing role of RhoB-F and RhoB-GG in Ras malignant transformation in NIH-3T3 cells. In addition, both RhoB (F/GG) and RhoB-GG induce apoptosis in Ras-transformed NIH-3T3 cells whereas RhoB-F has no effect. Our data demonstrate that RhoB-F and RhoB-GG which differ only by a 5-carbon isoprene behave differently in rodent cells highlighting the important role of prenyl groups in protein function and emphasize the potency of RhoB to regulate negatively the oncogenic signal.
Mazières
Julien
J
Département Innovation Thérapeutique et Oncologie Moléculaire, Centre de Physiopathologie Toulouse Purpan INSERM U563, Institut Claudius Regaud, 20-24 rue du Pont Saint-Pierre, 31052 Toulouse cedex, France.
Tillement
Vanessa
V
Allal
Cuider
C
Clanet
Carine
C
Bobin
Lisbeth
L
Chen
Zhi
Z
Sebti
Said M
SM
Favre
Gilles
G
Pradines
Anne
A
D000818:Animals; D017209:Apoptosis / Q000502:physiology; D049109:Cell Proliferation; D002471:Cell Transformation, Neoplastic / Q000235:genetics / Q000378:metabolism*; D015536:Down-Regulation / Q000502:physiology; D015972:Gene Expression Regulation, Neoplastic / Q000502:physiology; D051379:Mice; D009154:Mutation / Q000235:genetics; D016328:NF-kappa B / Q000378:metabolism; D041681:NIH 3T3 Cells; D017368:Protein Prenylation / Q000502:physiology*; D017346:Protein Serine-Threonine Kinases / Q000378:metabolism; D011518:Proto-Oncogene Proteins / Q000378:metabolism; D051057:Proto-Oncogene Proteins c-akt; D015398:Signal Transduction / Q000502:physiology; D025521:Tumor Suppressor Proteins / Q000235:genetics / Q000378:metabolism*; D015854:Up-Regulation / Q000502:physiology; D018631:ras Proteins / Q000378:metabolism*; D020743:rhoB GTP-Binding Protein / Q000235:genetics / Q000378:metabolism*
D016328:NF-kappa B; D011518:Proto-Oncogene Proteins; D025521:Tumor Suppressor Proteins; D017346:Protein Serine-Threonine Kinases; D051057:Proto-Oncogene Proteins c-akt; D018631:ras Proteins; D020743:rhoB GTP-Binding Protein