Regulation of the actin cytoskeleton may play a crucial role in cell motility and cancer invasion. We have produced a monoclonal antibody (NCC- Lu-632, IgM, k) reactive with an antigenic protein that is upregulated upon enhanced cell movement. The cDNA for the antigen molecule was found to encode a novel isoform of nonmuscle α-actinin. This isoform (designated actinin-4) was concentrated in the cytoplasm where cells were sharply extended and in cells migrating and located at the edge of cell clusters, but was absent from focal adhesion plaques or adherens junctions, where the classic isoform (actinin-1) was concentrated. Actinin-4 shifted steadily from the cytoplasm to the nucleus upon inhibition of phosphatidylinositol 3 kinase or actin depolymerization. The cytoplasmic localization of actinin-4 was closely associated with an infiltrative histological phenotype and correlated significantly with a poorer prognosis in 61 cases of breast cancer. These findings suggest that cytoplasmic actinin-4 regulates the actin cytoskeleton and increases cellular motility and that its inactivation by transfer to the nucleus abolishes the metastatic potential of human cancers.
Actinin-4, a Novel Actin-bundling Protein Associated with Cell Motility and Cancer Invasion
K. Honda is a recipient of a Research Resident Fellowship from the Foundation for Promotion of Cancer Research. This research was supported in part by a Grant-in-Aid for the Second Term Comprehensive 10-Year Strategy for Cancer Control from the Ministry of Health and Welfare, Japan.
The nucleotide sequence data reported in this paper will appear in the GenBank/EMBL/DDBJ nucleotide sequence databases under accession number D89980.
Address all correspondence to Setsuo Hirohashi, Pathology Division, National Cancer Center Research Institute, 1-1 Tsukiji 5-chome, Chuo-ku, Tokyo 104, Japan. Tel.: +81-3-3542-2511, ext. 4102. Fax: +81-3-3248-2737. E-mail: [email protected]
Kazufumi Honda, Tesshi Yamada, Ritsuko Endo, Yoshinori Ino, Masahiro Gotoh, Hitoshi Tsuda, Yozo Yamada, Hiroshige Chiba, Setsuo Hirohashi; Actinin-4, a Novel Actin-bundling Protein Associated with Cell Motility and Cancer Invasion . J Cell Biol 23 March 1998; 140 (6): 1383–1393. doi: https://doi.org/10.1083/jcb.140.6.1383
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