Clinical & Experimental Metastasis

, Volume 17, Issue 2, pp 141–148 | Cite as

Involvement of small GTPases Rho and Rac in the invasion of rat ascites hepatoma cells

  • Fumio Imamura
  • Mutsuko Mukai
  • Masako Ayaki
  • Koichi Takemura
  • Takeshi Horai
  • Kiyoko Shinkai
  • Hiroyuki Nakamura
  • Hitoshi Akedo


Lysophosphatidic acid (LPA) triggers the invasion of a mesothelial cell monolayer by rat ascites hepatoma (MM1) cells. LPA also induces rapid morphological changes of MM1 cells, cell surface blebbing and pseudopodia formation. Pseudopodia formation is tightly correlated with cellular invasiveness. Clostridium Botulinum C3 exoenzyme and genistein abrogated the formation of blebs and pseudopodia together with the inhibition of invasion, indicating that GTPase Rho and certain tyrosine kinases are involved in both processes. MM1 cells expressing constitutively active Rho exhibited the invasion and the formation of blebs and pseudopodia in the absence of LPA. In contrast, MM1 cells expressing constitutively active Rac were not invasive in the absence of LPA, but were invasive in the presence of LPA. Their morphological response to LPA was almost the same as that of parental MM1 cells. Expression of dominant negative Rac suppressed the invasiveness to approximately 3% of that of parental MM1 cells, together with the inhibition of pseudopodia formation. Thus, Rho and Rac are cooperatively involved in both the invasion and the related morphological changes of MM1 cells. Rho activation is sufficient both for the induction of invasion and the morphological changes leading to the invasion, whereas Rac activation is necessary but not sufficient by itself. We propose that Rho activation is not mediated by Rac but the cooperation of both GTPases is essential to trigger the invasive behavior of MM1 cells.

cell surface blebbing invasion pseudopodia rac rho 


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  1. 1.
    Habets GG, Scholtes EH, Zuydgeest D, van der Kammer RA, Stain JC, Berns A, Collard JG. Identification of an invasion-inducing gene gene, Tiam-1, that encodes a protein with a homology of GDP-GTP exchangers for Rho-like proteins. Cell 1995; 77: 537–49.Google Scholar
  2. 2.
    Michels F, Habets GG, Stain JC, van der Kammer RA, Collard JG. A role for Rac in Tiam1–induced membrane ruffling and invasion. Nature 1995; 375: 338–40.Google Scholar
  3. 3.
    Keely PJ, Westwick JK, Whitehead IP, Der CJ, Parise LV. Cdc42 and Rac1 induce integrin-mediated cell motility and invasiveness through PI 3–kinase. Nature 1997; 390: 632–36.Google Scholar
  4. 4.
    Shaw LM, Rabinovitz I, Wang HH, Toker A, Mercurio AM. Activation of phosphoinositide 3–OH kinase by the alpha6beta4 integrin promotes carcinoma invasion. Cell 1997; 91: 949–60.Google Scholar
  5. 5.
    Takaishi K, Sasaki T, Kato M, Yamochi W, Kuroda S, Nakamura T, Takeichi M, Takai T. Involvement of rho p21 small GTP-binding protein and its regulator in the HGF-induced cell motility. Oncogene 1994; 9: 273–79.Google Scholar
  6. 6.
    Akedo H, Shinkai K, Mukai M, Mori Y, Tateishi R, Tanaka K, Yamamoto R, Morishita T. Interaction of rat ascites hepatoma cells with cultured mesothelial cell monolayer: a model for cancer invasion. Cancer Res 1986; 46: 2416–22.Google Scholar
  7. 7.
    Imamura F, Horai T, Mukai, M, Shinkai K, Akedo H. Serum requirement for in vitro invasion by tumor cells. Jpn J Cancer Res 1991; 83: 493–96.Google Scholar
  8. 8.
    Imamura F, Horai T, Mukai M, Shinkai K, Sawada M, Akedo H. Induction of in vitro tumor cells invasion by lysophosphatidic acid or phospholipase D. Biochem Biophys Res Comm 1993; 193: 497–503.Google Scholar
  9. 9.
    Moolenaar WH. Lysophosphatidic acid: G-protein signalling and cellular responses. Curr Opin Cell Biol 1997; 9: 168–73.Google Scholar
  10. 10.
    Imamura F, Shinkai K, Mukai M, Yoshioka K, Komagome R, Iwasaki T, Akedo H. Rho-mediated protein tyrosine phosphorylation in lysophosphatidic-acid-induced tumor-cell invasion. Int J Cancer 1996; 65: 627–32.Google Scholar
  11. 11.
    Yoshioka K, Matsumura F, Akedo K, Itoh K. Small GTP-binding protein Rho stimulates the actomyosin system, leading to invasion of tumor cells. J Biol Chem 1998; 273: 5146–54.Google Scholar
  12. 12.
    Yoshioka K, Imamura F, Shinkai K, Miyoshi J, Ogawa H, Mukai M, Komagome R, Akedo H. Participation of rhop21 in serum-dependent invasion by rat ascites hepatoma cells. FEBS Lett 1995; 372: 25–28.Google Scholar
  13. 13.
    Stam JC, Michiels F, van der Kammen RA, Moolenaar WH, Collard JG. Invasion of T-lymphoma cells: cooperation between Rho family GTPases and lysophospholipid receptor signaling. EMBO J 1998; 17: 4066–74.Google Scholar
  14. 14.
    Nishiyama T, Sasaki T, Takaishi K, Kato M, Araki K, Matsuura Y, Takai Y. Rac p2l is involved in insulin-induced membrane ruffling and rho p21 is involved in hepatocyte growth factor-and 12–Otetradecanoylphorbol-13–acetate (TPA)-induced membrane ruffling in KB cells. Mol Cell Biol 1994; 14: 2447–56.Google Scholar
  15. 15.
    Ridley AJ, Comoglio PM, Hall A. Regulation of scatter factor/ hepatocyte growth factor response by Ras, Rac, and Rho in MDCK cells. Mol Cell Biol 1995; 15: 1110–12.Google Scholar
  16. 16.
    Mukai M, Shinkai K, Komatsu K, Akedo H. Potentiation of invasive capacity of rat ascites hepatoma cells by transforming growth factor-ß. Jpn J Cancer 1989; 80: 107–10.Google Scholar
  17. 17.
    Trinkaus JP. Formation of protrusions of the cell surface during tissue cell movement. Prog Clin Biol Res 1980; 41: 887–906.Google Scholar
  18. 18.
    Cunningham CC. Actin polymerization and intracellular solvent flow in cell surface blebbing. J Cell Biol 1995; 129: 1589–99.Google Scholar
  19. 19.
    Ridley AJ, Hall A. The small GTP-binding protein rho regulates the assembly of focal adhesions and stress fibers in response to growth factors. Cell 1992; 70: 389–99.Google Scholar
  20. 20.
    D'souza-Schorey C, Boettner B, Van Aelst L. Rac regulates integrinmediated spreading and increased adhesion of T lymphocytes. Mol Cell Biol 1998; 18(7): 3936–46.Google Scholar
  21. 21.
    Jalink K, van Corven EJ, Hangeveld T, Morii N, Narumiya S, Mollenaar WH. Inhibition of lysophosphatidate-and thrombin-induced neurite retraction and neuronal cell rounding ribosylation of the small GTP-binding protein Rho. J Cell Biol 1994; 126: 801–10.Google Scholar
  22. 22.
    Nakahara H, Mueller SC, Nomizu M, Yamada Y, Yeh Y, Chen W-T. Activation of ß1 integrin signaling stimulates tyrosine phosphorylation of p190RhoGAP and membrane-protrusive activities at invadopodia. J Biol Chem 1998: 273: 9–12.Google Scholar

Copyright information

© Kluwer Academic Publishers 1999

Authors and Affiliations

  • Fumio Imamura
    • 1
  • Mutsuko Mukai
    • 2
  • Masako Ayaki
    • 2
  • Koichi Takemura
    • 3
  • Takeshi Horai
    • 1
  • Kiyoko Shinkai
    • 2
  • Hiroyuki Nakamura
    • 2
  • Hitoshi Akedo
    • 2
  1. 1.Department of Pulmonary OncologyJapan
  2. 2.Tumor BiochemistryJapan
  3. 3.Department of PathologyOsaka Medical Center for Cancer and Cardiovascular DiseasesOsakaJapan

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