title: α-Actinin-4 is required for amoeboid-type invasiveness of melanoma cells.
abstract: α-Actinin-4 (ACTN4), a key regulator of the actin cytoskeleton, is up-regulated in melanoma, though its role in melanoma remains speculative. We have discovered that in WM1158, a highly aggressive melanoma cell line, down-regulation of ACTN4 by shRNA induces a collagen I-dependent amoeboidal-to-mesenchymal transition. Re-expression of low levels of WT ACTN4 but not similar expression levels of ACTN1 successfully restores the amoeboidal morphology and limits collagen I gel compaction. A truncated ACTN4 mutant 1-890, which lacks the C-terminal tail, fails to rescue the amoeboidal morphology and to compact collagen I gel. Interestingly, in three-dimensional collagen I gels, ACTN4 KD cells are more polarized compared with cells in which scrambled shRNA is expressed. Surprisingly, ACTN4 KD cells migrate faster than the ones expressing the scrambled shRNA on a collagen I gel (two-dimensional) although these two cell lines migrate similarly on tissue culture. Most importantly, down-regulation of ACTN4 significantly reduced invasion of WM1158 cells into the three-dimensional collagen I gel, a representative of the dermis. Taken together, these findings suggest that ACTN4 plays an important role in maintaining the amoeboidal morphology of invasive melanoma and thus promoting dissemination through collagen-rich matrices.
authors.affiliation: From the Departments of Pathology and.
authors.forename: Hanshuang
authors.initials: H
authors.lastname: Shao
authors.affiliation: Shady Side Academy, Pittsburgh, Pennsylvania 15238, and.
authors.forename: Shaoyan
authors.initials: S
authors.lastname: Li
authors.affiliation: Cell Biology and Physiology, and McGowan Institute of Regenerative Medicine, University of Pittsburgh, Pennsylvania 15213.
authors.forename: Simon C
authors.initials: SC
authors.lastname: Watkins
authors.affiliation: From the Departments of Pathology and the Laboratory and Pathology Service, Pittsburgh Veterans Affairs Health System, Pittsburgh, Pennsylvania 15213 wellsa@upmc.edu.
authors.forename: Alan
authors.initials: A
authors.lastname: Wells
mesh_terms: D000185:Actinin / Q000235:genetics / Q000378:metabolism*; D045744:Cell Line, Tumor; D002465:Cell Movement; D002478:Cells, Cultured; D024042:Collagen Type I / Q000378:metabolism*; D006801:Humans; D015151:Immunoblotting; D008545:Melanoma / Q000235:genetics / Q000378:metabolism / Q000473:pathology; D008856:Microscopy, Fluorescence; D009361:Neoplasm Invasiveness; D034622:RNA Interference; D012878:Skin Neoplasms / Q000235:genetics / Q000378:metabolism / Q000473:pathology
chemical_list: C111453:ACTN4 protein, human; D024042:Collagen Type I; D000185:Actinin
keywords: Cytoskeleton; Dermis; Epithelial-mesenchymal Transition (EMT); Invasion; Melanoma; Skin; Tumor Progression