AFAP-110 is required for actin stress fiber formation and cell adhesion in MDA-MB-231 breast cancer cells.
Regulation of actin organization and dynamics is a highly complex process that involves a number of actin-binding proteins, including capping, branching, severing, sequestering, and cross-linking proteins. The actin-binding and cross-linking protein AFAP-110 is expressed in normal myoepithelial cells. Screening of different breast epithelial cell lines revealed high expression levels of AFAP-110 in the human breast cancer cell lines MDA-MB-231 and MDA-MB-435. Knockdown of AFAP-110 expression in MDA-MB-231 cells does not result in any changes in cell proliferation but did result in a loss of actin stress fiber cross-linking and decreased adhesion to fibronectin. An inducible knockdown approach confirms that MDA-MB-231 breast cancer cells require AFAP-110 expression for stress fiber formation and adhesion. Thus, AFAP-110 may provide cytoskeletal tension through stress fiber formation, which is required for focal adhesion formation. Indeed, we could not detect any focal contacts or focal adhesions in AFAP-110 knockdown cells after adhesion to fibronectin. Although expression levels of crucial focal adhesion components were not influenced by AFAP-110 expression levels, treatment of AFAP-110 knockdown cells with LPA did not result in induction of actin stress fibers and focal adhesions. In summary, AFAP-110 plays an important role in MDA-MB-231 breast cancer cell adhesion possibly by regulating stress filament cross-linking which would promote focal adhesion formation.
Dorfleutner
Andrea
A
The Mary Babb Randolph Cancer Center and the Department of Microbiology, Immunology and Cell Biology, West Virginia University, Morgantown, West Virginia 26505-9300, USA.
Stehlik
Christian
C
Zhang
Jing
J
Gallick
Gary E
GE
Flynn
Daniel C
DC
D000199:Actins / Q000378:metabolism*; D020816:Amino Acid Motifs; D001943:Breast Neoplasms / Q000378:metabolism / Q000473:pathology*; D002448:Cell Adhesion / Q000502:physiology; D045744:Cell Line, Tumor; D003432:Cross-Linking Reagents / Q000378:metabolism; D005260:Female; D005353:Fibronectins / Q000378:metabolism; D006801:Humans; D008840:Microfilament Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D010750:Phosphoproteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D011485:Protein Binding; D017434:Protein Structure, Tertiary; D034741:RNA, Small Interfering / Q000378:metabolism; D022502:Stress Fibers / Q000378:metabolism*
C084510:AFAP 110; D000199:Actins; D003432:Cross-Linking Reagents; D005353:Fibronectins; D008840:Microfilament Proteins; D010750:Phosphoproteins; D034741:RNA, Small Interfering