title: β-PIX controls intracellular viscoelasticity to regulate lung cancer cell migration.
abstract: Cancer metastasis occurs via a progress involving abnormal cell migration. Cell migration, a dynamic physical process, is controlled by the cytoskeletal system, which includes the dynamics of actin organization and cellular adhesive organelles, focal adhesions (FAs). However, it is not known whether the organization of actin cytoskeletal system has a regulatory role in the physiologically relevant aspects of cancer metastasis. In the present studies, it was found that lung adenocarcinoma cells isolated from the secondary lung cancer of the lymph nodes, H1299 cells, show specific dynamics in terms of the actin cytoskeleton and FAs. This results in a higher level of mobility and this is regulated by an immature FA component, β-PIX (PAK-interacting exchange factor-β). In H1299 cells, β-PIX's activity was found not to be down-regulated by sequestration onto stress fibres, as the cells did not bundle actin filaments into stress fibres. Thus, β-PIX mainly remained localized at FAs, which allowed maturation of nascent adhesions into focal complexes; this resulted in actin polymerization, increased actin network integrity, changes in the intracellular microrheology at the peripheral of the cell, and cell polarity, which in turn regulated cell migration. Perturbation of β-PIX caused an inhibition of cell migration, including migration velocity, accumulated distance and directional persistence. Our results demonstrate the importance of β-PIX to the regulation of high mobility of lung adenocarcinoma cell line H1299 and that this occurs via regulation of FA dynamics, changes in actin cytoskeleton organization and cell polarity.
authors: Institute of Biochemistry and Molecular Biology, National Yang-Ming University, Taipei, Taiwan.
authors: Helen Wenshin
authors: HW
authors: Yu
authors: Yin-Quan
authors: YQ
authors: Chen
authors: Chi-Ming
authors: CM
authors: Huang
authors: Ching-Yi
authors: CY
authors: Liu
authors: Arthur
authors: A
authors: Chiou
authors: Yang-Kao
authors: YK
authors: Wang
authors: Ming-Jer
authors: MJ
authors: Tang
authors: Jean-Cheng
authors: JC
authors: Kuo
mesh_terms: D008841:Actin Cytoskeleton / Q000378:metabolism*; D000230:Adenocarcinoma / Q000378:metabolism / Q000473:pathology; D045744:Cell Line, Tumor; D002465:Cell Movement; D016764:Cell Polarity; D003593:Cytoplasm / Q000378:metabolism*; D015536:Down-Regulation; D004548:Elasticity; D022001:Focal Adhesions / Q000378:metabolism*; D006801:Humans; D008175:Lung Neoplasms / Q000378:metabolism / Q000473:pathology; D018613:Microscopy, Confocal; D024462:Myosin Type II / Q000378:metabolism; D034622:RNA Interference; D064067:Rho Guanine Nucleotide Exchange Factors / Q000235:genetics / Q000378:metabolism*; D022502:Stress Fibers / Q000378:metabolism; D059008:Time-Lapse Imaging / Q000379:methods; D014783:Viscosity
chemical_list: C576606:ARHGEF7 protein, human; D064067:Rho Guanine Nucleotide Exchange Factors; D024462:Myosin Type II
keywords: cell migration; cell stiffness; focal adhesions; non-small cell lung adenocarcinoma cells; stress fibres; viscoelasticity; β-PIX